Based on the fifth-generation reanalysis dataset from the European Centre for Medium-Range Weather Forecasts for 1979–2019,we investigated the effects of the circumglobal teleconnection(CGT)on the interdecadal variat...Based on the fifth-generation reanalysis dataset from the European Centre for Medium-Range Weather Forecasts for 1979–2019,we investigated the effects of the circumglobal teleconnection(CGT)on the interdecadal variation of the March atmospheric heat source(AHS)over the Southeast Asian low-latitude highlands(SEALLH).The dominant mode of the March AHS over the SEALLH features a monopole structure with an 8–11-year period.Decadal variations in the AHS make an important contribution to the 11-year low-pass filtered component of the AHS index,whichexplains 54.3%of the total variance.The CGT shows a clear interdecadal variation,which explains 59.3%of the total variance.The March AHS over the SEALLH is significantly related to the CGT on interdecadal timescales.When the CGT is optimally excited by a significant cyclonic vorticity source near northern Africa(i.e.,in its positive phase),the SEALLH is dominated by anomalous southerly winds and ascending motions on the east of the anomalous cyclone.The enhanced advection and upward transfer result in a high-enthalpy air mass that converges into and condenses over the SEALLH,leading to a largerthan-average March AHS over this region.The key physical processes revealed by this diagnostic analysis are supported by numerical experiments.展开更多
The influences of the wintertime AO (Arctic Oscillation) on the interdecadal variation of summer monsoon rainfall in East Asia were examined. An interdecadal abrupt change was found by the end of the 1970s in the vari...The influences of the wintertime AO (Arctic Oscillation) on the interdecadal variation of summer monsoon rainfall in East Asia were examined. An interdecadal abrupt change was found by the end of the 1970s in the variation of the AO index and the leading principal component time series of the summer rainfall in East Asia. The rainfall anomaly changed from below normal to above normal in central China, the southern part of northeastern China and the Korean peninsula around 1978. However, the opposite interdecadal variation was found in the rainfall anomaly in North China and South China. The interdecadal variation of summer rainfall is associated with the weakening of the East Asia summer monsoon circulation. It is indicated that the interdecadal variation of the AO exerts an influence on the weakening of the monsoon circulation. The recent trend in the AO toward its high-index polarity during the past two decades plays important roles in the land-sea contrast anomalies and wintertime precipitation anomaly. The mid- and high-latitude regions of the Asian continent are warming, while the low-latitude regions are cooling in winter and spring along with the AO entering its high-index polarity after the late 1970s. In the meantime, the precipitation over the Tibetan Plateau and South China is excessive, implying an increase of soil moisture. The cooling tendency of the land in the southern part of Asia will persist until summer because of the memory of soil moisture. So the warming of the Asian continent is relatively slow in summer. Moreover, the Indian Ocean and Pacific Ocean, which are located southward and eastward of the Asian land, are warming from winter to summer. This suggests that the contrast between the land and sea is decreased in summer. The interdecadal decrease of the land-sea heat contrast finally leads to the weakening of the East Asia summer monsoon circulation.展开更多
Decadal/interdecadal climate variability is an important research focus of the CLIVAR Program and has been paid more attention. Over recent years, a lot of studies in relation to interdecadal climate variations have b...Decadal/interdecadal climate variability is an important research focus of the CLIVAR Program and has been paid more attention. Over recent years, a lot of studies in relation to interdecadal climate variations have been also completed by Chinese scientists. This paper presents an overview of some advances in the study of decadal/interdecadal variations of the ocean temperature and its climate impacts, which includes interdccadal climate variability in China, the interdecadal modes of sea surface temperature (SST) anomalies in the North Pacific, and in particular, the impacts of interdecadal SST variations on the Asian monsoon rainfall. As summarized in this paper, some results have been achieved by using climate diagnostic studies of historical climatic datasets. Two fundamental interdecadal SST variability modes (7- 10-years mode and 25 35-years mode) have been identified over the North Pacific associated with different anomalous patterns of atmospheric circulation. The southern Indian Ocean dipole (SIOD) shows a major feature of interdecadal variation, with a positive (negative) phase favoring a weakened (enhanced) Asian summer monsoon in the following summer. It is also found that the China monsoon rainfall exhibits interdecadal variations with more wet (dry) monsoon years in the Yangtze River (South China and North China) before 1976, but vice versa after 1976. The weakened relationship between the Indian summer rainfall and ENSO is a feature of interdecadal variations, suggesting an important role of the interdecadal variation of the SIOD in the climate over the south Asia and southeast Asia. In addition, evidence indicates that the climate shift in the 1960s may be related to the anomalies of the North Atlantic Oscillation (NAO) and North Pacific Oscillation (NPO). Overall, the present research has improved our understanding of the decadal/interdecadal variations of SST and their impacts on the Asian monsoon rainfall. However, the research also highlights a number of problems for future research, in particular the mechanisms responsible for the monsoon long4erm predictability, which is a great challenge in climate research.展开更多
The interdecadal variation of Pacific thermocline represented by depth anomalies of 25σθ isopycnal surface calculated from SODA data set is analyzed. The climatological depth of 25σθ isopycnal surface is quit...The interdecadal variation of Pacific thermocline represented by depth anomalies of 25σθ isopycnal surface calculated from SODA data set is analyzed. The climatological depth of 25σθ isopycnal surface is quite close to the depth of 20 ℃ isotherm in the tropical Pacific. The EOF1 mode of the 25σθ isopycnal surface accounts for 26. 4% of the total variance and its associated pattern is of east-west direction. The centers of positive and negative extremes are located near 10oS over the southern Pacific and the correlation coefficient with zero-lag between the corresponding EOF1 time coefficient and PDO index is -0.67. This shows that there is very close relation between the southern tropical Pacific and PDO. The wavelet analysis of detrended EOF1 time coefficient reveals that there are two dominant time scales of about 3~7 and 30 a respectively. An apparent abruptness of mean value occurred in the late 1970s. EOF2 mode accounts for 12.4% of the total variance and its pattern is an ENSO-related one. The correlation coefficient between the EOF2 time coefficient and NINO3 index is -0.68. The wavelet analysis of EOF2 time coefficient reveals that there are two leading time scales of about 2~7 and 10~15 a respectively. On an interdecadal scale, the zonal change is consistent along the equator and is seesaw along 10oS; there is consistent polarity in the tropics along 165oE, but reverse polarity between around equator and other tropical region along 120oW. In all the four profiles mentioned above, the regime shift occurred in the late 1970s. The evolving characteristics of anomalies can be explained mostly by the anomalies of ocean currents during a complete cycle on an interdecadal scale.展开更多
Evaporation controlled by meteorological parameters plays a crucial role in hydrology, meteorology and water resources management. An insight view of long-term variation in evaporation will help understanding the effe...Evaporation controlled by meteorological parameters plays a crucial role in hydrology, meteorology and water resources management. An insight view of long-term variation in evaporation will help understanding the effects of climate change and provide useful information for rational utilization of water resources, especially in the arid land where the shortage of water resources exists. However, the lack of data on evaporation led to difficulties in assessing the impacts of climate change on evaporation, especially in arid mountainous area. This study investigated the long-term variation of the pan-evaporation (Ep) measured by E601 type evaporation pan and its influencing climatic factors at both northern and southern slopes of the Tianshan Mountains in Xinjiang of China using the ensemble empirical mode decomposition method and Path analysis. The results revealed that Eps at both northern and southern slopes had obvious interdecadal variation within cycles of 3-4 and 7-8 years. Eps at both slopes sharply decreased in early 1980s, but increased after late 1990s. Path analysis showed that the 3-4 years cycle of Ep at the northern and southern slopes was mainly dependent upon actual water vapor pressure with a negative direct path coefficient of-0.515 and sunshine duration with a positive direct path coefficient of 0.370, respectively. The variation of Ep with cycle of 7-8 years at the northern slope was attributed to the wind speed with a direct path coefficient of 0.774. Average temperature had a direct path coefficient of 0.813 in 7-8 years cycle at the southern slope. The assessment of Ep variation and its causes provides information essential for a good understanding of hydrologic cycle and regional climate of arid mountainous regions in Xinjiang of China and offers a theoretical reference for distribution and utilization of water resources.展开更多
This study aims to explore the interdecadal variation of South Asian High(SAH) and its relationship with SST(sea surface temperature) of the tropical and subtropical regions by using the NCEP/NCAR monthly reanalysis d...This study aims to explore the interdecadal variation of South Asian High(SAH) and its relationship with SST(sea surface temperature) of the tropical and subtropical regions by using the NCEP/NCAR monthly reanalysis data from 1948 to 2012, based on the NCAR CAM 3.0 general circulation model. The results show that: 1) the intensity of SAH represents a remarkable interdecadal variation characteristic, the intensity of SAH experienced from weak to strong at the late 1970 s, and after the late 1970 s, its strength is enhanced and the area is expanded in the east-west direction.The expansion degree is greater westward than eastward, while it is opposite in summer. 2) Corresponding to the interdecadal variation of SAH intensity, after the late 1970 s, the divergent component of wind field has two ascending and three descending areas. Of the two ascending areas, one is located in the East Pacific, the other location varies with the season from the Indian Ocean in winter to the South China Sea and West Pacific in summer. Three descending areas are located in the north-central Africa, the East Asia and the Middle Pacific region respectively. 3) Corresponding to the interdecadal variation of SAH intensity, the rotational component of wind field at the lower level is an anomalous cyclone over the South China Sea and West Pacific in summer, while in winter, it is an anomalous cyclone over the Indian Ocean, and an anomalous anticyclone over the equatorial Middle Pacific. 4) Numerical simulations show that the interdecadal variation of SAH is closely related to the SST of the tropical and subtropical regions. The SST of Indian Ocean plays an important role in winter, while in summer, the SST of the South China Sea and West Pacific plays an important role, and the SST of the East Pacific also plays a certain role.展开更多
Phase delays between two Nino indices-sea surface temperatures in Nino regions 1+2 and 3.4 (1950-2001)-at different time scales are detected by wavelet analysis. Analysis results show that there are two types of perio...Phase delays between two Nino indices-sea surface temperatures in Nino regions 1+2 and 3.4 (1950-2001)-at different time scales are detected by wavelet analysis. Analysis results show that there are two types of period bifurcations in the Nino indices and that period bifurcation points exist only in the region where the wavelet power is small. Interdecadal variation features of phase delays between the two indices vary with different time scales. In the periods of 40-72 months, the phase delay changes its sign in 1977: Nino 1+2 indices are 2-4 months earlier than Nino 3.4 indices before 1977, but 3-6 months later afterwards. In the periods of 20-40 months, however, the phase delay changes its sign in another way: Nino 1+2 indices are 1-4 months earlier before 1980 and during 1986-90, but 1-4 months later during 1980-83 and 1993-2001.展开更多
The characteristics and possible physical mechanism of interdecadal variation of the intensity of the South Asian High(SAH) in summer are analyzed using the NCEP/NCAR reanalysis data and NOAA extended reconstructed se...The characteristics and possible physical mechanism of interdecadal variation of the intensity of the South Asian High(SAH) in summer are analyzed using the NCEP/NCAR reanalysis data and NOAA extended reconstructed sea surface temperature(SST) data.The results indicate that a remarkable interdecadal transition occurred in the late1970 s that increased the intensity of SAH,or,an abrupt climate change was around 1978.A comparative analysis between the weak and strong period of the SAH intensity shows that the related anomalous patterns of the atmospheric circulation(including wind field,air temperature field and vertical velocity field) are nearly opposite to each other.The surface latent heat flux anomalies over the plateau(especially in the northwest of the plateau) in summer exert great influence on the interdecadal variation of the SAH intensity and the surface sensible heat flux anomalies play a more important role.Consistent with the interdecadal variation of the SAH intensity,the monopole mode of the tropical Indian Ocean SST in summer also experienced a low to high transition in the late 1970 s.To some extent,this can reveal the impact of the anomalous monopole mode of the tropical Indian Ocean SST in summer on interdecadal variation of the SAH.展开更多
Based on the drought/flood grades of 90 meterological stations over eastern China and summer average sea-level pressure (SLP) during 1850-2008 and BPCCA statistical methods, the coupling relationship between the dro...Based on the drought/flood grades of 90 meterological stations over eastern China and summer average sea-level pressure (SLP) during 1850-2008 and BPCCA statistical methods, the coupling relationship between the drought/flood grades and the East Asian summer SLP is analyzed. The East Asian summer monsoon index which is closely related with interdecadal variation of drought/flood distribution over eastern China is defined by using the key areas of SLP. The impact of the interdecadal variation of the East Asian summer monsoon on the distribution of drought/flood over eastern China in the last 159 years is researched. The results show that there are four typical drought and flood spatial distribution patterns in eastern China, i.e. the distribution of drought/flood in southern China is contrary to the other regions, the distribution of drought/flood along the Huanghe River–Huaihe River Valley is contrary to the Yangtze River Valley and regions south of it, the distribution of drought/flood along the Yangtze River Valley and Huaihe River Valley is contrary to the other regions, the distribution of drought/flood in eastern China is contrary to the western. The main distribution pattern of SLP in summer is that the strength of SLP is opposite in Asian continent and West Pacific. It has close relationship between the interdecadal variation of drought/flood distribution patterns over eastern China and the interdecadal variation of the East Asian summer monsoon which was defined in this paper, but the correlation is not stable and it has a significant difference in changes of interdecadal phase. When the East Asian summer monsoon was stronger (weaker), regions north of the Yangtze River Valley was more susceptible to drought (flood), the Yangtze River Valley and regions south of it were more susceptible to flood (drought) before the 1920s; when the East Asian summer monsoon was stronger (weaker), the regions north of the Yangtze River Valley was prone to flood (drought), the Yangtze River Valley and regions south of it were prone to drought (flood) after the 1920s. It is indicated that by using the data of the longer period could get much richer results than by using the data of the last 50–60 years. The differences in the interdecadal phase between the East Asian summer monsoon and the drought/flood distributions in eastern China may be associated with the nonlinear feedback, which is the East Asian summer monsoon for the extrinsic forcing of solar activity.展开更多
This paper discusses the interdecadal changes of the climate in the tropical Pacific with a focus on the correspond- ing changes in the characteristics of the E1 Nifio-Southern Oscillation (ENSO). Compared with 1979...This paper discusses the interdecadal changes of the climate in the tropical Pacific with a focus on the correspond- ing changes in the characteristics of the E1 Nifio-Southern Oscillation (ENSO). Compared with 1979-1999, the whole tropical Pacific climate system, including both the ocean and atmosphere, shifted to a lower variability regime after 1999/2000. Meanwhile, the frequency of ENSO became less regular and was closer to a white noise process. The lead time of the equatorial Pacific's subsurface ocean heat content in preceding ENSO decreased remarkably, in addition to a reduction in the maximum correlation between them. The weakening of the correlation and the shorten- ing of the lead time pose more challenges for ENSO prediction, and is the likely reason behind the decrease in skill with respect to ENSO prediction after 2000. Coincident with the changes in tropical Pacific climate variability, the mean states of the atmospheric and oceanic components also experienced physically coherent changes. The warm an- omaly of SST in the western Pacific and cold anomaly in the eastern Pacific resulted in an increased zonal SST gradi- ent, linked to an enhancement in surface wind stress and strengthening of the Walker circulation, as well as an in- crease in the slope of the thermocline. These changes were consistent with an increase (a decrease) in precipitation and an enhancement (a suppression) of the deep convection in the western (eastern) equatorial Pacific. Possible con- nections between the mean state and ENSO variability and frequency changes in the tropical Pacific are also dis- cussed.展开更多
Using the output data of 20 coupled climate models used in IPCC AR4 and observational data from NCEP, the capability of the models to simulate the boreal winter climatology of the East Asian sea level pressure, 850-hP...Using the output data of 20 coupled climate models used in IPCC AR4 and observational data from NCEP, the capability of the models to simulate the boreal winter climatology of the East Asian sea level pressure, 850-hPa wind, and surface air temperature; the decadal variations of the East Asian winter mon- soon (EAWM) intensity and EAWM-related circulation, and the interdecadal variations of EAWM-related circulation are systematically evaluated. The results indicate that 16 models can weakly simulate the declin- ing trend of the EAWM in the 1980s. More than half of the models produce relatively reasonable decadal variations of the EAWM-related circulation and the interdecadal differences of EAWM-related circulation between the boreal winters of 1960-1985 and 1986-1998, including the weakened Siberian high, Aleutian low, and East Asian trough, the enhanced Arctic oscillation and North Pacific oscillation, and a deepened polar vortex. It is found that the performance of the multi-selected-model ensemble in reproducing the spatial dis- tribution of the variations is encouraging, although the variational amplitudes are generally smaller than the observations. In addition, it is found that BCCR-BCM2.0, CGCM3.1-T63, CNRM-CM3, CSIRO-MK3.0, GISS-ER, INM-CM3.0, and MRI-CGCM2.3.2 perform well in every aspect.展开更多
Investigated statistically is the interrelation between East Asian winter monsoon(EAWM) and SST over sensitive areas of the Indian and Pacific Oceans.with focus on the relation of EAWM to strong ENSO signal area.i.e.,...Investigated statistically is the interrelation between East Asian winter monsoon(EAWM) and SST over sensitive areas of the Indian and Pacific Oceans.with focus on the relation of EAWM to strong ENSO signal area.i.e.,the equatorial eastern Pacific(EEP)SST.Evidence suggests that the EAWM variation is intimately associated not only with the EEP SST but with the equatorial western Pacific“warm pool”and equatorial Indian/northwestern Pacific Kuroshio SST as well:the EAWM and ENSO interact strongly with each other on the interannual time scales, exhibiting pronounced interdecadal variation mainly under the joint effect of the monsoon QBO and the monsoon/SST background field features on an interdecadal basis—when both fields are in the same phase(anti-phase).strong EAWM contributes to EEP SST rise(drop)in the following winter,corresponding to a warm(cold)ENSO cycle;the EAWM QBO causes ENSO cycle to be strong phase-locked with seasonal variation,making the EEP SST rise lasting from April—May to May—June of the next year,which plays an important role in maintaining a warm ENSO phase.展开更多
We use 71-yr(1948–2018) reanalysis data to investigate the interdecadal variation in the atmospheric heat source(Q1) over the Tibetan Plateau and surrounding Asian monsoon region(AMTP) and its effect on the Northern ...We use 71-yr(1948–2018) reanalysis data to investigate the interdecadal variation in the atmospheric heat source(Q1) over the Tibetan Plateau and surrounding Asian monsoon region(AMTP) and its effect on the Northern Hemisphere summer circulation. The large-scale circulation driven by Q1 over the AMTP is characterized by a center of convergent(divergent) or low(high) potential wind function in the lower(upper) troposphere. Q1 over the AMTP shows a clear interdecadal variation(with positive–negative–positive phases) and these three phases correspond to the time periods 1948–1972, 1973–2005, and 2006–2018, respectively. The thermal circulation has a corresponding interdecadal variation as a response to the interdecadal variation in Q1. An enhanced Q1 leads to an increase in the conversion of the total potential energy to non-divergent wind kinetic energy via the divergent wind velocity. The maximum conversion occurs in the tropopause. The primary thermal forcing for Q1 is produced by the intense, large volume precipitation of the summer monsoon. This induces a response in the large-scale circulation, leading to largescale divergence patterns. The synergistic effects of Pacific Decadal Oscillation(PDO) and North Atlantic Multidecadal Oscillation(AMO) influence Q1 over the AMTP, which is ultimately responsible for the modulation of variations in the global divergent circulation. The global divergent circulation in summer is therefore essentially a direct thermodynamic circulation driven by the strong Q1 over the AMTP.展开更多
The interdecadal variation of intensity of the western Pacific subtropical high(WPSH) during the period 1951-2001 is studied by using data from the National Climate Center(NCC),China Meteorological Administration....The interdecadal variation of intensity of the western Pacific subtropical high(WPSH) during the period 1951-2001 is studied by using data from the National Climate Center(NCC),China Meteorological Administration.The characteristics of the circulations at 500 hPa and the surface heat flux over East Asia are also analyzed based on the NCEP/NCAR monthly reanalysis data.The results reveal that the WPSH and the circulations exhibit interdecadal variations around 1978,with enhancing intensities.The interseasonal persistence of the WPSH intensity alters correspondingly to some extent,which is more significant during 1978-2001 than during 1951-1978.The surface heat flux over East Asia also displays a remarkable interdecadal variation,which leads that of the WPSH intensity.The key variation areas of the surface sensible heat flux(SSHF) are mainly located over the eastern and western Tibetan Plateau around the late 1960s.However,the difference of the SSHF between the eastern and western Plateau exhibits a change in the mid 1970s,close to the time of the abrupt climate change of the WPSH intensity.The SSHF of the Plateau stably increases in the west and decreases in the east before the mid-late 1960s,while it stably increases in the east and decreases in the west after the mid-1970s.On the other hand,the key variation area of the surface latent heat flux(SLHF) is mainly situated over the West Pacific(WP),where the SLHF anomaly in spring changes from positive to negative in the south before 1978,but from negative to positive in the north after 1978;while in summer it turns from positive to negative all over the WP after 1978.The interdecadal variation of SLHF in both spring and summer corresponds well to the interdecadal variation of the WPSH intensity in the same season.The notable correlation between the WPSH intensity and SSHF(or SLHF) maintains without any change although each of these qnantities varies on the interdecadal scale.展开更多
Decadal/interdecadal climate variability is an important element in the CLIVAR (Climate Variability and Predictability) and has received much attention in the world. Many studies in relation to interdecadal variation ...Decadal/interdecadal climate variability is an important element in the CLIVAR (Climate Variability and Predictability) and has received much attention in the world. Many studies in relation to interdecadal variation have also been completed by Chinese scientists in recent years. In this paper, an introduction in outline for interdecadal climate variation research in China is presented. The content includes the features of interdecadal climate variability in China, global warming and interdecadal temperature variability, the NAO (the North Atlantic Oscillation)/NPO (the North Pacific Oscillation) and interdecadal climate variation in China, the interdecadal variation of the East Asian monsoon, the interdecadal mode of SSTA (Sea Surface Temperature Anomaly) in the North Pacific and its climate impact, and abrupt change feature of the climate.展开更多
This article discusses the interannual variation of the North Atlantic Oscillation (NAO) and North Pacific Oscillation (NPO), its relationship with the interdecadal climate variation in China which is associated with ...This article discusses the interannual variation of the North Atlantic Oscillation (NAO) and North Pacific Oscillation (NPO), its relationship with the interdecadal climate variation in China which is associated with the climate jump in the Northern Hemisphere in the 1960’s, using the data analyses. It is clearly shown that both the amplitudes of the NAO and NPO increase obviously in the 1960’s and the main period of the oscillations changes from 3-4 years before the 1960’s to 8–15 years after the 1960’s. Therefore, interdecadal climate variation in China or the climate jump in the 1960’s is closely related to the anomalies of the NAO and NPO. Key words North Atlantic Oscillation (NAO) - North Pacific Oscillation (NPO) - Climate Jump - Interdecadal climate variation This work was supported by National Key Basic Science Program in China (G1998040903), Chinese Academy of Science and the National Natural Science Fundation of China (Grant No.49823002).The authors are also grateful to Ms. Wang Xuan for typing the manuscript.展开更多
The Tibetan Plateau(TP)and the Arctic are the most sensitive regions to global climate change.However,the interdecadal varibility of winter extreme precipitation over the TP and its linkage with Arctic sea ice are sti...The Tibetan Plateau(TP)and the Arctic are the most sensitive regions to global climate change.However,the interdecadal varibility of winter extreme precipitation over the TP and its linkage with Arctic sea ice are still unclear.In this study,the characteristics and mechisnems of the TP extreme precipitation(TPEP)influenced by Arctic sea ice on interdecadal timescale are studied based on the daily precipitation,monthly sea ice concentration and ERA5 reanalysis data from 1980 to 2018.We found that the dominant mode of the TPEP in winter mostly exhibits a uniform spatial variation on the interdecadal timescale,with an opposite weak variation in the southeastern TP,and the Arctic sea ice concentration(SIC)before 2002 are larger than that after 2003.The interdecadal variation of TPEP is affected by two teleconnection wave trains regulated by the Barents and Kara Sea ice.In the light ice years,a remarkable positive geopotential height(HGT)anomaly appears over the Barents-Kara Sea and a remarkable negative HGT anomaly is located over the Lake Baikal.Two wave trains originating over the Barents-Kara Sea can be observed.The southern branch forms a wave train through the North Atlantic along the subtropical westerly jet stream,showing a‘+-+-+'pattern of HGT anomalies from Arctic to the TP.Negative HGT anomaly controls the western TP,which creates dynamic and water vapor conditions for the TPEP.The northern branch forms a wave train through the Lake Baikal and the southeast of the TP,showing a‘+-+'HGT anomaly distribution.Positive HGT anomaly controls the southeastern TP,which is not conducive to precipitation in the region.When the SIC in the Barents-Kara Sea increases,the situation is opposite.The above analysis also reveals the reason for the difference in the east-west distribution of the TPEP.展开更多
Based on the meteorological data during 1959-2008 from five representative weather stations in the Urumqi River Basin and surrounding areas,the regional characteristics of temperature and precipitation in the basin fe...Based on the meteorological data during 1959-2008 from five representative weather stations in the Urumqi River Basin and surrounding areas,the regional characteristics of temperature and precipitation in the basin featuring multi-climatic zones were studied by means of some methods including wavelet analysis.As was shown in the results,the temperature in the whole Urumqi River Basin demonstrated a significant upward trend.The temperature increase particularly in autumn and winter made the greatest contribution to the marked ascent.The interdecadal temperature in the basin showed a tendency to decline before the period during 1970s-1980s while it was on the rise after 1990s on the whole.The most concentrated period of temperature mutations was in the late 1990s.At the same time,the precipitation also showed an escalating trend,which experienced a stage of unanimous upward trend after 1990s.The most concentrated period of precipitation mutations was in the early 1990s.展开更多
Wavelet analyses are applied to the Pacific Decadal Oscillation index and North Pacific index for the period 1900-2000, which identifies two dominant interdecadal components, the bidecadal (15-25-yr) and pentadecadal ...Wavelet analyses are applied to the Pacific Decadal Oscillation index and North Pacific index for the period 1900-2000, which identifies two dominant interdecadal components, the bidecadal (15-25-yr) and pentadecadal (50 70-yr) modes. Joint propagating patterns of sea surface temperature (SST) and sea level pressure (SLP) anomalies in the North Pacific for the two modes are revealed by using the techniques of multi-channel singular spectrum analysis (MSSA) and linear regression analysis with the global sea surface temperature (GISST) data and the northern hemispheric SLP data for the common period 1903 1998. Significant differences in spatio-temporal structures are found between the two modes. For the bidecadal mode, SST anomalies originating from the Gulf of Alaska appear to slowly spread southwestward, inducing a reversal of early SST anomalies in the central North Pacific. Due to further westward spreading, the SST variation of the central North Pacific leads that of the Kuroshio-Oyashio Extension (KOE) region by approximately 4 to 5 years. Concomitantly, SLP anomalies spread over most parts of the North Pacific during the mature phase and then change into an NPO(North Pacific Oscillation)-like pattern during the transition phase. For the pentadecadal mode, SST anomalies develop in the southeast tropical Pacific and propagate along the North American coast to the mid-latitudes; meanwhile, SST anomalies with the same polarity in the western tropical Pacific expand northward to Kuroshio and its extension region; both merge into the central North Pacific reversing the sign of early SST anomalies there. Accompanying SLP anomalies are characterized by an NPO-like pattern during the mature phase while they are dominant over the North Pacific during the transitional phase. The bidecadal and pentadecadal modes have different propagating patterns, suggesting that the two interdecadal modes may arise from different physical mechanisms.展开更多
In our previous study, a statistical linkage between the spring Arctic sea ice concentration (SIC) and the succeeding Chinese summer rainfall during the period 1968-2005 was identified. This linkage is demonstrated ...In our previous study, a statistical linkage between the spring Arctic sea ice concentration (SIC) and the succeeding Chinese summer rainfall during the period 1968-2005 was identified. This linkage is demonstrated by the leading singular value decomposition (SVD) that accounts for 19% of the co-variance. Both spring SIC and Chinese summer rainfall exhibit a coherent interannual variability and two apparent interdecadal variations that occurred in the late 1970s and the early 1990s. The combined impacts of both spring Arctic SIC and Eurasian snow cover on the summer Eurasian wave train may explain their statistical linkage. In this study, we show that evolution of atmospheric circulation anomalies from spring to summer, to a great extent, may explain the spatial distribution of spring and summer Arctic SIC anomalies, and is dynamically consistent with Chinese summer rainfall anomalies in recent decades. The association between spring Arctic SIC and Chinese summer rainfall on interannual time scales is more important relative to interdecadal time scales. The summer Arctic dipole anomaly may serve as the bridge linking the spring Arctic SIC and Chinese summer rainfall, and their coherent interdecadal variations may reflect the feedback of spring SIC variability on the atmosphere. The summer Arctic dipole anomaly shows a closer relationship with the Chinese summer rainfall relative to the Arctic Oscillation.展开更多
基金This work was supported by the National Natural Science Foundation of China(Grant No.42030603)the Natural Science Foundation of Yunnan Province(2019FY003006)the Postgraduate Research and Innovation foundation of Yunnan University(2021Z017).
文摘Based on the fifth-generation reanalysis dataset from the European Centre for Medium-Range Weather Forecasts for 1979–2019,we investigated the effects of the circumglobal teleconnection(CGT)on the interdecadal variation of the March atmospheric heat source(AHS)over the Southeast Asian low-latitude highlands(SEALLH).The dominant mode of the March AHS over the SEALLH features a monopole structure with an 8–11-year period.Decadal variations in the AHS make an important contribution to the 11-year low-pass filtered component of the AHS index,whichexplains 54.3%of the total variance.The CGT shows a clear interdecadal variation,which explains 59.3%of the total variance.The March AHS over the SEALLH is significantly related to the CGT on interdecadal timescales.When the CGT is optimally excited by a significant cyclonic vorticity source near northern Africa(i.e.,in its positive phase),the SEALLH is dominated by anomalous southerly winds and ascending motions on the east of the anomalous cyclone.The enhanced advection and upward transfer result in a high-enthalpy air mass that converges into and condenses over the SEALLH,leading to a largerthan-average March AHS over this region.The key physical processes revealed by this diagnostic analysis are supported by numerical experiments.
基金This research was supported by the National Natural Science Foundation of China un-der Grant No.40233033.
文摘The influences of the wintertime AO (Arctic Oscillation) on the interdecadal variation of summer monsoon rainfall in East Asia were examined. An interdecadal abrupt change was found by the end of the 1970s in the variation of the AO index and the leading principal component time series of the summer rainfall in East Asia. The rainfall anomaly changed from below normal to above normal in central China, the southern part of northeastern China and the Korean peninsula around 1978. However, the opposite interdecadal variation was found in the rainfall anomaly in North China and South China. The interdecadal variation of summer rainfall is associated with the weakening of the East Asia summer monsoon circulation. It is indicated that the interdecadal variation of the AO exerts an influence on the weakening of the monsoon circulation. The recent trend in the AO toward its high-index polarity during the past two decades plays important roles in the land-sea contrast anomalies and wintertime precipitation anomaly. The mid- and high-latitude regions of the Asian continent are warming, while the low-latitude regions are cooling in winter and spring along with the AO entering its high-index polarity after the late 1970s. In the meantime, the precipitation over the Tibetan Plateau and South China is excessive, implying an increase of soil moisture. The cooling tendency of the land in the southern part of Asia will persist until summer because of the memory of soil moisture. So the warming of the Asian continent is relatively slow in summer. Moreover, the Indian Ocean and Pacific Ocean, which are located southward and eastward of the Asian land, are warming from winter to summer. This suggests that the contrast between the land and sea is decreased in summer. The interdecadal decrease of the land-sea heat contrast finally leads to the weakening of the East Asia summer monsoon circulation.
基金the Chinese Academy of Sciences (KZCX3-SW- 226) the National Natureal Science Foundation of China (Grant No. 40233033).
文摘Decadal/interdecadal climate variability is an important research focus of the CLIVAR Program and has been paid more attention. Over recent years, a lot of studies in relation to interdecadal climate variations have been also completed by Chinese scientists. This paper presents an overview of some advances in the study of decadal/interdecadal variations of the ocean temperature and its climate impacts, which includes interdccadal climate variability in China, the interdecadal modes of sea surface temperature (SST) anomalies in the North Pacific, and in particular, the impacts of interdecadal SST variations on the Asian monsoon rainfall. As summarized in this paper, some results have been achieved by using climate diagnostic studies of historical climatic datasets. Two fundamental interdecadal SST variability modes (7- 10-years mode and 25 35-years mode) have been identified over the North Pacific associated with different anomalous patterns of atmospheric circulation. The southern Indian Ocean dipole (SIOD) shows a major feature of interdecadal variation, with a positive (negative) phase favoring a weakened (enhanced) Asian summer monsoon in the following summer. It is also found that the China monsoon rainfall exhibits interdecadal variations with more wet (dry) monsoon years in the Yangtze River (South China and North China) before 1976, but vice versa after 1976. The weakened relationship between the Indian summer rainfall and ENSO is a feature of interdecadal variations, suggesting an important role of the interdecadal variation of the SIOD in the climate over the south Asia and southeast Asia. In addition, evidence indicates that the climate shift in the 1960s may be related to the anomalies of the North Atlantic Oscillation (NAO) and North Pacific Oscillation (NPO). Overall, the present research has improved our understanding of the decadal/interdecadal variations of SST and their impacts on the Asian monsoon rainfall. However, the research also highlights a number of problems for future research, in particular the mechanisms responsible for the monsoon long4erm predictability, which is a great challenge in climate research.
基金This study was supported by the National Science Foundation of China under contract No.40136010the Chinese Academy of Sciences under contract No.ZKCX2-SW-210.
文摘The interdecadal variation of Pacific thermocline represented by depth anomalies of 25σθ isopycnal surface calculated from SODA data set is analyzed. The climatological depth of 25σθ isopycnal surface is quite close to the depth of 20 ℃ isotherm in the tropical Pacific. The EOF1 mode of the 25σθ isopycnal surface accounts for 26. 4% of the total variance and its associated pattern is of east-west direction. The centers of positive and negative extremes are located near 10oS over the southern Pacific and the correlation coefficient with zero-lag between the corresponding EOF1 time coefficient and PDO index is -0.67. This shows that there is very close relation between the southern tropical Pacific and PDO. The wavelet analysis of detrended EOF1 time coefficient reveals that there are two dominant time scales of about 3~7 and 30 a respectively. An apparent abruptness of mean value occurred in the late 1970s. EOF2 mode accounts for 12.4% of the total variance and its pattern is an ENSO-related one. The correlation coefficient between the EOF2 time coefficient and NINO3 index is -0.68. The wavelet analysis of EOF2 time coefficient reveals that there are two leading time scales of about 2~7 and 10~15 a respectively. On an interdecadal scale, the zonal change is consistent along the equator and is seesaw along 10oS; there is consistent polarity in the tropics along 165oE, but reverse polarity between around equator and other tropical region along 120oW. In all the four profiles mentioned above, the regime shift occurred in the late 1970s. The evolving characteristics of anomalies can be explained mostly by the anomalies of ocean currents during a complete cycle on an interdecadal scale.
基金funded by the National Basic Research Program of China(2012CB956204)the Special Funds for Key Laboratories of the Xinjiang Uygur Autonomous Region(2014KL015)
文摘Evaporation controlled by meteorological parameters plays a crucial role in hydrology, meteorology and water resources management. An insight view of long-term variation in evaporation will help understanding the effects of climate change and provide useful information for rational utilization of water resources, especially in the arid land where the shortage of water resources exists. However, the lack of data on evaporation led to difficulties in assessing the impacts of climate change on evaporation, especially in arid mountainous area. This study investigated the long-term variation of the pan-evaporation (Ep) measured by E601 type evaporation pan and its influencing climatic factors at both northern and southern slopes of the Tianshan Mountains in Xinjiang of China using the ensemble empirical mode decomposition method and Path analysis. The results revealed that Eps at both northern and southern slopes had obvious interdecadal variation within cycles of 3-4 and 7-8 years. Eps at both slopes sharply decreased in early 1980s, but increased after late 1990s. Path analysis showed that the 3-4 years cycle of Ep at the northern and southern slopes was mainly dependent upon actual water vapor pressure with a negative direct path coefficient of-0.515 and sunshine duration with a positive direct path coefficient of 0.370, respectively. The variation of Ep with cycle of 7-8 years at the northern slope was attributed to the wind speed with a direct path coefficient of 0.774. Average temperature had a direct path coefficient of 0.813 in 7-8 years cycle at the southern slope. The assessment of Ep variation and its causes provides information essential for a good understanding of hydrologic cycle and regional climate of arid mountainous regions in Xinjiang of China and offers a theoretical reference for distribution and utilization of water resources.
基金National Natural Science Foundation for Yong Scholars(41105059,41305079)General Program of the National Natural Science Foundation of China(41575070,41230422,41575102)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘This study aims to explore the interdecadal variation of South Asian High(SAH) and its relationship with SST(sea surface temperature) of the tropical and subtropical regions by using the NCEP/NCAR monthly reanalysis data from 1948 to 2012, based on the NCAR CAM 3.0 general circulation model. The results show that: 1) the intensity of SAH represents a remarkable interdecadal variation characteristic, the intensity of SAH experienced from weak to strong at the late 1970 s, and after the late 1970 s, its strength is enhanced and the area is expanded in the east-west direction.The expansion degree is greater westward than eastward, while it is opposite in summer. 2) Corresponding to the interdecadal variation of SAH intensity, after the late 1970 s, the divergent component of wind field has two ascending and three descending areas. Of the two ascending areas, one is located in the East Pacific, the other location varies with the season from the Indian Ocean in winter to the South China Sea and West Pacific in summer. Three descending areas are located in the north-central Africa, the East Asia and the Middle Pacific region respectively. 3) Corresponding to the interdecadal variation of SAH intensity, the rotational component of wind field at the lower level is an anomalous cyclone over the South China Sea and West Pacific in summer, while in winter, it is an anomalous cyclone over the Indian Ocean, and an anomalous anticyclone over the equatorial Middle Pacific. 4) Numerical simulations show that the interdecadal variation of SAH is closely related to the SST of the tropical and subtropical regions. The SST of Indian Ocean plays an important role in winter, while in summer, the SST of the South China Sea and West Pacific plays an important role, and the SST of the East Pacific also plays a certain role.
基金This work was supported by the National Natural Science Foundation of China under Grant No.40035010
文摘Phase delays between two Nino indices-sea surface temperatures in Nino regions 1+2 and 3.4 (1950-2001)-at different time scales are detected by wavelet analysis. Analysis results show that there are two types of period bifurcations in the Nino indices and that period bifurcation points exist only in the region where the wavelet power is small. Interdecadal variation features of phase delays between the two indices vary with different time scales. In the periods of 40-72 months, the phase delay changes its sign in 1977: Nino 1+2 indices are 2-4 months earlier than Nino 3.4 indices before 1977, but 3-6 months later afterwards. In the periods of 20-40 months, however, the phase delay changes its sign in another way: Nino 1+2 indices are 1-4 months earlier before 1980 and during 1986-90, but 1-4 months later during 1980-83 and 1993-2001.
基金State Key Basic Study Program of China("973",2010CB950401)National Science Foundation of China(41275086)
文摘The characteristics and possible physical mechanism of interdecadal variation of the intensity of the South Asian High(SAH) in summer are analyzed using the NCEP/NCAR reanalysis data and NOAA extended reconstructed sea surface temperature(SST) data.The results indicate that a remarkable interdecadal transition occurred in the late1970 s that increased the intensity of SAH,or,an abrupt climate change was around 1978.A comparative analysis between the weak and strong period of the SAH intensity shows that the related anomalous patterns of the atmospheric circulation(including wind field,air temperature field and vertical velocity field) are nearly opposite to each other.The surface latent heat flux anomalies over the plateau(especially in the northwest of the plateau) in summer exert great influence on the interdecadal variation of the SAH intensity and the surface sensible heat flux anomalies play a more important role.Consistent with the interdecadal variation of the SAH intensity,the monopole mode of the tropical Indian Ocean SST in summer also experienced a low to high transition in the late 1970 s.To some extent,this can reveal the impact of the anomalous monopole mode of the tropical Indian Ocean SST in summer on interdecadal variation of the SAH.
基金National Natural Science Foundation of China No.40890053 Special Scientific Fund for Non-profit Public Industry (Meteorology) No.GYHY200906016 No.GYHY201006038
文摘Based on the drought/flood grades of 90 meterological stations over eastern China and summer average sea-level pressure (SLP) during 1850-2008 and BPCCA statistical methods, the coupling relationship between the drought/flood grades and the East Asian summer SLP is analyzed. The East Asian summer monsoon index which is closely related with interdecadal variation of drought/flood distribution over eastern China is defined by using the key areas of SLP. The impact of the interdecadal variation of the East Asian summer monsoon on the distribution of drought/flood over eastern China in the last 159 years is researched. The results show that there are four typical drought and flood spatial distribution patterns in eastern China, i.e. the distribution of drought/flood in southern China is contrary to the other regions, the distribution of drought/flood along the Huanghe River–Huaihe River Valley is contrary to the Yangtze River Valley and regions south of it, the distribution of drought/flood along the Yangtze River Valley and Huaihe River Valley is contrary to the other regions, the distribution of drought/flood in eastern China is contrary to the western. The main distribution pattern of SLP in summer is that the strength of SLP is opposite in Asian continent and West Pacific. It has close relationship between the interdecadal variation of drought/flood distribution patterns over eastern China and the interdecadal variation of the East Asian summer monsoon which was defined in this paper, but the correlation is not stable and it has a significant difference in changes of interdecadal phase. When the East Asian summer monsoon was stronger (weaker), regions north of the Yangtze River Valley was more susceptible to drought (flood), the Yangtze River Valley and regions south of it were more susceptible to flood (drought) before the 1920s; when the East Asian summer monsoon was stronger (weaker), the regions north of the Yangtze River Valley was prone to flood (drought), the Yangtze River Valley and regions south of it were prone to drought (flood) after the 1920s. It is indicated that by using the data of the longer period could get much richer results than by using the data of the last 50–60 years. The differences in the interdecadal phase between the East Asian summer monsoon and the drought/flood distributions in eastern China may be associated with the nonlinear feedback, which is the East Asian summer monsoon for the extrinsic forcing of solar activity.
基金Supported by the China Meteorological Administration Special Public Welfare Research Fund(GYHY201506013)
文摘This paper discusses the interdecadal changes of the climate in the tropical Pacific with a focus on the correspond- ing changes in the characteristics of the E1 Nifio-Southern Oscillation (ENSO). Compared with 1979-1999, the whole tropical Pacific climate system, including both the ocean and atmosphere, shifted to a lower variability regime after 1999/2000. Meanwhile, the frequency of ENSO became less regular and was closer to a white noise process. The lead time of the equatorial Pacific's subsurface ocean heat content in preceding ENSO decreased remarkably, in addition to a reduction in the maximum correlation between them. The weakening of the correlation and the shorten- ing of the lead time pose more challenges for ENSO prediction, and is the likely reason behind the decrease in skill with respect to ENSO prediction after 2000. Coincident with the changes in tropical Pacific climate variability, the mean states of the atmospheric and oceanic components also experienced physically coherent changes. The warm an- omaly of SST in the western Pacific and cold anomaly in the eastern Pacific resulted in an increased zonal SST gradi- ent, linked to an enhancement in surface wind stress and strengthening of the Walker circulation, as well as an in- crease in the slope of the thermocline. These changes were consistent with an increase (a decrease) in precipitation and an enhancement (a suppression) of the deep convection in the western (eastern) equatorial Pacific. Possible con- nections between the mean state and ENSO variability and frequency changes in the tropical Pacific are also dis- cussed.
基金Supported by the National Natural Science Foundation of China(41130103 and 40905041)Knowledge Innovation Program of the Chinese Academy of Sciences(KZCX2-YW-QN202)China Global Change Research Program(2012CB955401)
文摘Using the output data of 20 coupled climate models used in IPCC AR4 and observational data from NCEP, the capability of the models to simulate the boreal winter climatology of the East Asian sea level pressure, 850-hPa wind, and surface air temperature; the decadal variations of the East Asian winter mon- soon (EAWM) intensity and EAWM-related circulation, and the interdecadal variations of EAWM-related circulation are systematically evaluated. The results indicate that 16 models can weakly simulate the declin- ing trend of the EAWM in the 1980s. More than half of the models produce relatively reasonable decadal variations of the EAWM-related circulation and the interdecadal differences of EAWM-related circulation between the boreal winters of 1960-1985 and 1986-1998, including the weakened Siberian high, Aleutian low, and East Asian trough, the enhanced Arctic oscillation and North Pacific oscillation, and a deepened polar vortex. It is found that the performance of the multi-selected-model ensemble in reproducing the spatial dis- tribution of the variations is encouraging, although the variational amplitudes are generally smaller than the observations. In addition, it is found that BCCR-BCM2.0, CGCM3.1-T63, CNRM-CM3, CSIRO-MK3.0, GISS-ER, INM-CM3.0, and MRI-CGCM2.3.2 perform well in every aspect.
基金Supported by the National Natural Science Foundation of China under Grant ATM-49705062.
文摘Investigated statistically is the interrelation between East Asian winter monsoon(EAWM) and SST over sensitive areas of the Indian and Pacific Oceans.with focus on the relation of EAWM to strong ENSO signal area.i.e.,the equatorial eastern Pacific(EEP)SST.Evidence suggests that the EAWM variation is intimately associated not only with the EEP SST but with the equatorial western Pacific“warm pool”and equatorial Indian/northwestern Pacific Kuroshio SST as well:the EAWM and ENSO interact strongly with each other on the interannual time scales, exhibiting pronounced interdecadal variation mainly under the joint effect of the monsoon QBO and the monsoon/SST background field features on an interdecadal basis—when both fields are in the same phase(anti-phase).strong EAWM contributes to EEP SST rise(drop)in the following winter,corresponding to a warm(cold)ENSO cycle;the EAWM QBO causes ENSO cycle to be strong phase-locked with seasonal variation,making the EEP SST rise lasting from April—May to May—June of the next year,which plays an important role in maintaining a warm ENSO phase.
基金the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA20100304)Second Tibetan Plateau Scientific Expedition and Research Program (2019QZKK0208)+1 种基金National Natural Science Foundation of China (41790471)National Key Scientific Research Plan of China (2016YFA0602200)。
文摘We use 71-yr(1948–2018) reanalysis data to investigate the interdecadal variation in the atmospheric heat source(Q1) over the Tibetan Plateau and surrounding Asian monsoon region(AMTP) and its effect on the Northern Hemisphere summer circulation. The large-scale circulation driven by Q1 over the AMTP is characterized by a center of convergent(divergent) or low(high) potential wind function in the lower(upper) troposphere. Q1 over the AMTP shows a clear interdecadal variation(with positive–negative–positive phases) and these three phases correspond to the time periods 1948–1972, 1973–2005, and 2006–2018, respectively. The thermal circulation has a corresponding interdecadal variation as a response to the interdecadal variation in Q1. An enhanced Q1 leads to an increase in the conversion of the total potential energy to non-divergent wind kinetic energy via the divergent wind velocity. The maximum conversion occurs in the tropopause. The primary thermal forcing for Q1 is produced by the intense, large volume precipitation of the summer monsoon. This induces a response in the large-scale circulation, leading to largescale divergence patterns. The synergistic effects of Pacific Decadal Oscillation(PDO) and North Atlantic Multidecadal Oscillation(AMO) influence Q1 over the AMTP, which is ultimately responsible for the modulation of variations in the global divergent circulation. The global divergent circulation in summer is therefore essentially a direct thermodynamic circulation driven by the strong Q1 over the AMTP.
基金Supported by the National Key Basic Research Program of China under Grant Nos. 2004CB418300, 2010CB950102 and 2010CB833404National Natural Science Foundation of China under Grant Nos. 40675042, 40871007 and 40890054Key Innovation Project of the Chinese Academy of Sciences under Grant No. KZCX2-YW-337
文摘The interdecadal variation of intensity of the western Pacific subtropical high(WPSH) during the period 1951-2001 is studied by using data from the National Climate Center(NCC),China Meteorological Administration.The characteristics of the circulations at 500 hPa and the surface heat flux over East Asia are also analyzed based on the NCEP/NCAR monthly reanalysis data.The results reveal that the WPSH and the circulations exhibit interdecadal variations around 1978,with enhancing intensities.The interseasonal persistence of the WPSH intensity alters correspondingly to some extent,which is more significant during 1978-2001 than during 1951-1978.The surface heat flux over East Asia also displays a remarkable interdecadal variation,which leads that of the WPSH intensity.The key variation areas of the surface sensible heat flux(SSHF) are mainly located over the eastern and western Tibetan Plateau around the late 1960s.However,the difference of the SSHF between the eastern and western Plateau exhibits a change in the mid 1970s,close to the time of the abrupt climate change of the WPSH intensity.The SSHF of the Plateau stably increases in the west and decreases in the east before the mid-late 1960s,while it stably increases in the east and decreases in the west after the mid-1970s.On the other hand,the key variation area of the surface latent heat flux(SLHF) is mainly situated over the West Pacific(WP),where the SLHF anomaly in spring changes from positive to negative in the south before 1978,but from negative to positive in the north after 1978;while in summer it turns from positive to negative all over the WP after 1978.The interdecadal variation of SLHF in both spring and summer corresponds well to the interdecadal variation of the WPSH intensity in the same season.The notable correlation between the WPSH intensity and SSHF(or SLHF) maintains without any change although each of these qnantities varies on the interdecadal scale.
基金supported by the National Natural Science Foundation of China(Grant No.40233033)the Chinese Academy of Sciences(ZKCX2-SW-210 and KZCX2-203).
文摘Decadal/interdecadal climate variability is an important element in the CLIVAR (Climate Variability and Predictability) and has received much attention in the world. Many studies in relation to interdecadal variation have also been completed by Chinese scientists in recent years. In this paper, an introduction in outline for interdecadal climate variation research in China is presented. The content includes the features of interdecadal climate variability in China, global warming and interdecadal temperature variability, the NAO (the North Atlantic Oscillation)/NPO (the North Pacific Oscillation) and interdecadal climate variation in China, the interdecadal variation of the East Asian monsoon, the interdecadal mode of SSTA (Sea Surface Temperature Anomaly) in the North Pacific and its climate impact, and abrupt change feature of the climate.
基金This work was supported by National Key Basic Science Program in China !(G 1998040903)Chinese Academy of Science and the Nat
文摘This article discusses the interannual variation of the North Atlantic Oscillation (NAO) and North Pacific Oscillation (NPO), its relationship with the interdecadal climate variation in China which is associated with the climate jump in the Northern Hemisphere in the 1960’s, using the data analyses. It is clearly shown that both the amplitudes of the NAO and NPO increase obviously in the 1960’s and the main period of the oscillations changes from 3-4 years before the 1960’s to 8–15 years after the 1960’s. Therefore, interdecadal climate variation in China or the climate jump in the 1960’s is closely related to the anomalies of the NAO and NPO. Key words North Atlantic Oscillation (NAO) - North Pacific Oscillation (NPO) - Climate Jump - Interdecadal climate variation This work was supported by National Key Basic Science Program in China (G1998040903), Chinese Academy of Science and the National Natural Science Fundation of China (Grant No.49823002).The authors are also grateful to Ms. Wang Xuan for typing the manuscript.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program of China (2019QZKK0208)the National Key Research and Development Program of China (2022YFE0136000,2023YFF0805104)+2 种基金the National Natural Science Foundation of China (U2242207,42305018,42105037)the Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies (2020B1212060025)the Innovative Development Special Project of China Meteorological Administration (CXFZ2022J039,CXFZ2023J003).
文摘The Tibetan Plateau(TP)and the Arctic are the most sensitive regions to global climate change.However,the interdecadal varibility of winter extreme precipitation over the TP and its linkage with Arctic sea ice are still unclear.In this study,the characteristics and mechisnems of the TP extreme precipitation(TPEP)influenced by Arctic sea ice on interdecadal timescale are studied based on the daily precipitation,monthly sea ice concentration and ERA5 reanalysis data from 1980 to 2018.We found that the dominant mode of the TPEP in winter mostly exhibits a uniform spatial variation on the interdecadal timescale,with an opposite weak variation in the southeastern TP,and the Arctic sea ice concentration(SIC)before 2002 are larger than that after 2003.The interdecadal variation of TPEP is affected by two teleconnection wave trains regulated by the Barents and Kara Sea ice.In the light ice years,a remarkable positive geopotential height(HGT)anomaly appears over the Barents-Kara Sea and a remarkable negative HGT anomaly is located over the Lake Baikal.Two wave trains originating over the Barents-Kara Sea can be observed.The southern branch forms a wave train through the North Atlantic along the subtropical westerly jet stream,showing a‘+-+-+'pattern of HGT anomalies from Arctic to the TP.Negative HGT anomaly controls the western TP,which creates dynamic and water vapor conditions for the TPEP.The northern branch forms a wave train through the Lake Baikal and the southeast of the TP,showing a‘+-+'HGT anomaly distribution.Positive HGT anomaly controls the southeastern TP,which is not conducive to precipitation in the region.When the SIC in the Barents-Kara Sea increases,the situation is opposite.The above analysis also reveals the reason for the difference in the east-west distribution of the TPEP.
基金Supported by National Key Basic Research Development Program of China(2010CB951003,2007CB411501)Knowledge Innovation Program of Chinese Academy of Sciences(KZCX2-EW-311,KZCX2-YW127)+2 种基金Project Funded by National Natural Science Foundation of China(40631001,9102501240571033,40701034,40371028, J0630966,40701035)Autonomous Subject of State Key Laboratory of Cryospheric Sciences(SKLCS-ZZ-2010-04)~~
文摘Based on the meteorological data during 1959-2008 from five representative weather stations in the Urumqi River Basin and surrounding areas,the regional characteristics of temperature and precipitation in the basin featuring multi-climatic zones were studied by means of some methods including wavelet analysis.As was shown in the results,the temperature in the whole Urumqi River Basin demonstrated a significant upward trend.The temperature increase particularly in autumn and winter made the greatest contribution to the marked ascent.The interdecadal temperature in the basin showed a tendency to decline before the period during 1970s-1980s while it was on the rise after 1990s on the whole.The most concentrated period of temperature mutations was in the late 1990s.At the same time,the precipitation also showed an escalating trend,which experienced a stage of unanimous upward trend after 1990s.The most concentrated period of precipitation mutations was in the early 1990s.
基金supported by the National Natural Science Foundation of China under the grants No.40233028 and No.40075017.
文摘Wavelet analyses are applied to the Pacific Decadal Oscillation index and North Pacific index for the period 1900-2000, which identifies two dominant interdecadal components, the bidecadal (15-25-yr) and pentadecadal (50 70-yr) modes. Joint propagating patterns of sea surface temperature (SST) and sea level pressure (SLP) anomalies in the North Pacific for the two modes are revealed by using the techniques of multi-channel singular spectrum analysis (MSSA) and linear regression analysis with the global sea surface temperature (GISST) data and the northern hemispheric SLP data for the common period 1903 1998. Significant differences in spatio-temporal structures are found between the two modes. For the bidecadal mode, SST anomalies originating from the Gulf of Alaska appear to slowly spread southwestward, inducing a reversal of early SST anomalies in the central North Pacific. Due to further westward spreading, the SST variation of the central North Pacific leads that of the Kuroshio-Oyashio Extension (KOE) region by approximately 4 to 5 years. Concomitantly, SLP anomalies spread over most parts of the North Pacific during the mature phase and then change into an NPO(North Pacific Oscillation)-like pattern during the transition phase. For the pentadecadal mode, SST anomalies develop in the southeast tropical Pacific and propagate along the North American coast to the mid-latitudes; meanwhile, SST anomalies with the same polarity in the western tropical Pacific expand northward to Kuroshio and its extension region; both merge into the central North Pacific reversing the sign of early SST anomalies there. Accompanying SLP anomalies are characterized by an NPO-like pattern during the mature phase while they are dominant over the North Pacific during the transitional phase. The bidecadal and pentadecadal modes have different propagating patterns, suggesting that the two interdecadal modes may arise from different physical mechanisms.
基金supported by the National Key Basic Research and Development Project of China(Grant Nos2004CB418300 and 2007CB411505)Chinese COPES project(GYHY200706005)the Na-tional Natural Science Foundation of China(Grant No40875052)
文摘In our previous study, a statistical linkage between the spring Arctic sea ice concentration (SIC) and the succeeding Chinese summer rainfall during the period 1968-2005 was identified. This linkage is demonstrated by the leading singular value decomposition (SVD) that accounts for 19% of the co-variance. Both spring SIC and Chinese summer rainfall exhibit a coherent interannual variability and two apparent interdecadal variations that occurred in the late 1970s and the early 1990s. The combined impacts of both spring Arctic SIC and Eurasian snow cover on the summer Eurasian wave train may explain their statistical linkage. In this study, we show that evolution of atmospheric circulation anomalies from spring to summer, to a great extent, may explain the spatial distribution of spring and summer Arctic SIC anomalies, and is dynamically consistent with Chinese summer rainfall anomalies in recent decades. The association between spring Arctic SIC and Chinese summer rainfall on interannual time scales is more important relative to interdecadal time scales. The summer Arctic dipole anomaly may serve as the bridge linking the spring Arctic SIC and Chinese summer rainfall, and their coherent interdecadal variations may reflect the feedback of spring SIC variability on the atmosphere. The summer Arctic dipole anomaly shows a closer relationship with the Chinese summer rainfall relative to the Arctic Oscillation.