Under the influence of anthropogenic and climate change,the problems caused by urban heat island(UHI)has become increasingly prominent.In order to promote urban sustainable development and improve the quality of human...Under the influence of anthropogenic and climate change,the problems caused by urban heat island(UHI)has become increasingly prominent.In order to promote urban sustainable development and improve the quality of human settlements,it is significant for exploring the evolution characteristics of urban thermal environment and analyzing its driving forces.Taking the Landsat series images as the basic data sources,the winter land surface temperature(LST)of the rapid urbanization area of Fuzhou City in China was quantitatively retrieved from 2001 to 2021.Combing comprehensively the standard deviation ellipse model,profile analysis and GeoDetector model,the spatio-temporal evolution characteristics and influencing factors of the winter urban thermal environment were systematically analyzed.The results showed that the winter LST presented an increasing trend in the study area during 2001–2021,and the winter LST of the central urban regions was significantly higher than the suburbs.There was a strong UHI effect from 2001 to 2021with an expansion trend from the central urban regions to the suburbs and coastal areas in space scale.The LST of green lands and wetlands are significantly lower than croplands,artificial surface and unvegetated lands.Vegetation and water bodies had a significant mitigation effect on UHI,especially in the micro-scale.The winter UHI had been jointly driven by the underlying surface and socio-economic factors in a nonlinear or two-factor interactive enhancement mode,and socio-economic factors had played a leading role.This research could provide data support and decision-making references for rationally planning urban layout and promoting sustainable urban development.展开更多
The author investigates the prediction of Northeast China's winter surface air temperature (SAT),and first forecast the year to year increment in the predic-tand and then predict the predictand.Thus,in the first s...The author investigates the prediction of Northeast China's winter surface air temperature (SAT),and first forecast the year to year increment in the predic-tand and then predict the predictand.Thus,in the first step,we determined the predictors for an increment in winter SAT by analyzing the atmospheric variability associated with an increment in winter SAT.Then,multi-linear re-gression was applied to establish a prediction model for an increment in winter SAT in Northeast China.The pre-diction model shows a high correlation coefficient (0.73) between the simulated and observed annual increments in winter SAT in Northeast China throughout the period 1965-2002,with a relative root mean square error of -7.9%.The prediction model makes a reasonable hindcast for 2003-08,with an average relative root mean square error of -7.2%.The prediction model can capture the in-creasing trend of winter SAT in Northeast China from 1965-2008.The results suggest that this approach to forecasting an annual increment in winter SAT in North-east China would be relevant in operational seasonal forecasts.展开更多
This paper addresses the interannual variation of winter air temperature over Northeast China and its connection to preceding Eurasian snow cover. The results show that there is a significant negative correlation betw...This paper addresses the interannual variation of winter air temperature over Northeast China and its connection to preceding Eurasian snow cover. The results show that there is a significant negative correlation between October Eurasian snow cover and following-winter air temperature over Northeast China. The snow cover located in eastern Siberia and to the northeast of Lake Baikal plays an important role in the winter air temperature anomaly. More (less) eastern Siberia snow in October can cause an atmospheric circulation anomaly pattern in which the atmospheric pressure is higher (lower) than normal in the polar region and lower (higher) in the northern mid-high latitudes. Due to the persistence of the eastern Siberia snow from October to the following winter, the winter atmospheric anomaly is favorable (unfavorable) to the widespread movement of cold air masses from the polar region toward the northern mid-high latitudes and, hence, lower (higher) temperature over Northeast China. Simultaneously, when the October snow cover is more (less), the SST in the northwestern Pacific is continuously lower (higher) as a whole; then, the Aleutian low and the East Asia trough are reinforced (weakened), favoring the lower (higher) temperature over Northeast China.展开更多
This paper presents a statistical scheme for the seasonal forecasting of North China's surface air temperature (NCSAT) during winter. Firstly, a prediction model for an decrease or increase of winter NCSAT is esta...This paper presents a statistical scheme for the seasonal forecasting of North China's surface air temperature (NCSAT) during winter. Firstly, a prediction model for an decrease or increase of winter NCSAT is established, whose predictors are available for no later than the previous September, as this is the most favorable month for seasonal forecasting up to two months ahead.The predicted NCSAT is then derived as the sum of the predicted increment of NCSAT and the previous NCSAT. The scheme successfully predicts the interannual and the decadal variability of NCSAT. Additionally, the advantages of the prediction scheme are discussed.展开更多
The winter temperature changes in East China during the past 100 years are investigated by using the Twentieth Century Version 2(20th-v2)Reanalysis.Four typical warm(P1,1911–30;P4,1991–2010)and cold(P2,1938–57;P3,1...The winter temperature changes in East China during the past 100 years are investigated by using the Twentieth Century Version 2(20th-v2)Reanalysis.Four typical warm(P1,1911–30;P4,1991–2010)and cold(P2,1938–57;P3,1961–80)periods are identified for the East China winter temperature index.Comparison of160-station observational data,NCAR sea level pressure(SLP)data,and NCEP/NCAR Reanalysis shows that the20th-v2 Reanalysis can successfully depict the major features of the warming from P3 to P4,which is part of the global warming phenomenon.The cooling from P1 to P2is a regional phenomenon under global warming.However,both changes are consistent with the phase change of the Arctic Oscillation(AO),while the second change is also accompanied by the phase change of Antarctic Oscillation(AAO)from negative to positive.Original sources of the interdecadal shifts of the AO and winter temperature in East China require further research.展开更多
[Objective] The research aimed to study the distribution characteristics of winter continuous extreme low temperature in China. [Method] Based on the daily minimum temperature data in winter during 1961-2008 in 195 ob...[Objective] The research aimed to study the distribution characteristics of winter continuous extreme low temperature in China. [Method] Based on the daily minimum temperature data in winter during 1961-2008 in 195 observatories, the continuous extreme low temperature event (cold night) which happened in winter in China and the distribution characteristics of accumulated temperature anomaly in 48 years were analyzed by using the actual probability distribution threshold method. [Result] Besides in Northeast China, Northwest China and Qinghai-Tibet Plateau where the geographical position was northerly, and the altitude was high, the long-time (above 5 d) extreme low temperature event was also easy to happen in the south of Yangtze River, especially in Guizhou, Guangxi, Hunan and so on. The continuous extreme low temperature event in the middle and lower reaches of Yellow River was the least. Started from the metaphase of the 1980s, the frequency trend of continuous extreme low temperature event decreased. But in 1992, 2000 and 2007, the low temperature event which continued above 7 d was more than the average. The accumulated cold in January in 48 years was the strongest. The second one was in February, and the smallest was in December. The accumulated cold in Northeast China and the north of Inner Mongolia was the biggest in December and January. The accumulated cold in the north of Xinjiang was the biggest in February. In the whole winter, the accumulated cold in Qinghai-Tibet Plateau was the smallest. The chilling injury was easier to happen in Guizhou, Guangxi and Hunan than other south areas in December and February. The occurrence probability of chilling injury in most areas of Szechwan Basin, Yunnan and Qinling Mountains in central China was smaller than that in other areas. [Conclusion] The research provided the reference basis for analyzing the influence of chilling injury on the agriculture in China.展开更多
Based on monthly mean surface air temperature (SAT) from 71 stations in northern China and NCEP/ NCAR and NOAA-CIRES (Cooperative Institute for Research in Environmental Sciences) twentieth century reanalysis data...Based on monthly mean surface air temperature (SAT) from 71 stations in northern China and NCEP/ NCAR and NOAA-CIRES (Cooperative Institute for Research in Environmental Sciences) twentieth century reanalysis data, the dominant modes of winter SAT over northem China were explored. The results showed that there are two modes that account for a majority of the total variance over northern China. The first mode is unanimously colder (warmer) over the whole of northern China. The second mode is characterized by a dipole structure that is colder (warmer) over Northwest China (NWC) and warmer (colder) over Northeast China (NEC), accounting for a fairly large proportion of the total variance. The two components constituting the second mode, the individual variations of winter SAT over NWC and NEC and their respective preceding factors, were further investigated. It was found that the autumn SAT anomalies are closely linked to persistent snow cover anomalies over Eurasia, showing the delayed effects on winter climate over northern China. Specifically, the previous autumn SAT anomalies over the Lake Baikal (LB; 50-60°N, 85-120°E) and Mongolian Plateau (MP; 42-52°N, 80-120°E) regions play an important role in adjusting the variations of winter SAT over NWC and NEC, respectively. The previous autumn SAT anomaly over the MP region may exert an influence on the winter SAT over NEC through modulating the strength and location of the East Asian major trough. The previous autumn SAT over the LB region may modulate winter westerlies at the middle and high latitudes of Asia and accordingly affects the invasion of cold air and associated winter SAT over NWC.展开更多
We extracted 374 pieces of records of frost date from historical documents. Using these records, we reconstructed winter half-year (October to next April) temperature series, with a resolution of 5-year, for the North...We extracted 374 pieces of records of frost date from historical documents. Using these records, we reconstructed winter half-year (October to next April) temperature series, with a resolution of 5-year, for the North China Plain during 1651-2010. The results show that the temperature changes in the North China Plain were divided into four phases. With the reference period of 1951-1980, two cold phases, 1651-1700 and 1781-1900, have cold anomaly of 0.83°C and 0.60°C respectively. However, between the two cold phases, 1701-1780 was a relative warm phase with the cold anomaly of 0.36°C referring to the mean of 1951-1980. After the 1900, the climate came into a warm phase. The mean temperature of 1901-2010 was 0.11°C higher than the mean of 1951-1980. During 1651-2010, the 1996-2000 is the warmest 5-year with the warm anomaly of 1.25°C than that of the reference period of 1951-1980.展开更多
[Objective] The study aimed to discuss the relationship between temperature variation in winter of China and arctic oscillation. [Method] By using the NCEP/NCAR reanalysis data, AO index series and monthly temperature...[Objective] The study aimed to discuss the relationship between temperature variation in winter of China and arctic oscillation. [Method] By using the NCEP/NCAR reanalysis data, AO index series and monthly temperature data from 160 stations of China, the variation characteris- tics of temperature in winter and AO index series as well as their relationship from 1951 to 2007 were studied. [Result] Temperature in winter of Chi- na correlated positively with AO index series. Both arctic oscillation and winter temperature in China had two major periods of 8 and 18 years. ⅠWTr and ⅠAO series, which had obvious inter-annual and inter-decadal variations, presented the almost same rising trend and had close relationship on an inter-decadal scale. Compared with AO, the Siberia high had more distinguished influences on inter-annual variations of temperature in winter of China. AO might affect changes in the Siberian high and thereby influence temperature in winter of China. AO had a greater influence on tempera- ture in winter of China than the Siberia high on an inter-decadal scale. When the East Asian through was weak, temperature in winter of China and AO index were low, while they were high as it was strong. The impact of AO index on an inter-decadal scale was more significant than the impact on an inter-annual scale. [ Condusien] The research could make the effects of AO on winter temperature of China clear.展开更多
Using NCEP/NCAR R2 reanalysis daily data and daily meteorologicalobservational data of southwest China in 2010, this paper studied the submonthlytimescale oscillation characteristics of the East Asian winter monsoon (...Using NCEP/NCAR R2 reanalysis daily data and daily meteorologicalobservational data of southwest China in 2010, this paper studied the submonthlytimescale oscillation characteristics of the East Asian winter monsoon (EAWM) and itseffect on the temperature of southwest China in 2010 by bandpass filtering, wavelettransformation, composite analysis and correlation analysis. The main conclusions areas follows: The EAWM in 2010 was dominated by low-frequency oscillations of about 7-,12-, and 30-day periods. There existed obviously negative correlation between theEAWM and the winter temperature in southwest China on submonthly, quasi-weeklyand quasi-biweekly timescales, and negative correlation was more obvious on thequasi-biweekly than the quasi-weekly timescale. There was significant difference in thedistribution of high, middle and low layer of the troposphere when the EAWM was onthe submonthly, quasi-one-week and quasi-two-week timescales in the positive andnegative phase. In the positive EAWM phase, the upper-level subtropical westerly jet isstronger and the East Asia trough is deeper, thus it is favorable for the dominance ofmore powerful north wind and lower temperature in southwest China. On the contrary,in the negative EAWM phase, the upper-level subtropical westerly jet is weaker and theEast Asia trough is shallower, thus unfavorable for the north wind and lowertemperature in southwest China.展开更多
The global surface temperature change since the mid-19th century has caused general concern and intensive study. However, long-term changes in the marginal seas, including the seas east of China, are not well understo...The global surface temperature change since the mid-19th century has caused general concern and intensive study. However, long-term changes in the marginal seas, including the seas east of China, are not well understood because long-term observations are sparse and, even when they exist, they are over limited areas. Preliminary results on the long-term variability of sea surface temperature (SST) in summer and winter in the seas east of China during the period of 1957-2001 are reported using the Ocean Science Database of Institute of Oceanology, Chinese Academy of Sciences, the coastal hydrological station in situ and satellite data. The results show well-defined warming trends in the study area. However warming and cooling trends vary from decade to decade, with steady and rapid warming trends after the 1980s and complicated spatial patterns. The distribution of SST variation is intricate and more blurred in the areas far away from the Kuroshio system. Both historical and satellite data sets show significant warming trends after 1985. The warming trends are larger and spread to wider areas in winter than in summer, which means decrease in the seasonal cycle of SST probably linked with recently observed increase of the tropical zooplankton species in the region. Spatial structures of the SST trends are roughly consistent with the circulation pattern especially in winter when the meridional SST gradients are larger, suggesting that a horizontal advection may play an important role in the long-term SST variability in winter.展开更多
[Objective] The research aimed to study the variation characteristics of winter temperature in Jinan in recent 60 years.[Method] Based on winter monthly average,maximum and minimum temperatures in the ground observati...[Objective] The research aimed to study the variation characteristics of winter temperature in Jinan in recent 60 years.[Method] Based on winter monthly average,maximum and minimum temperatures in the ground observation station of Jinan during 1951-2010,by using linear trend,5-year moving average and anomaly,the variation characteristics of winter average,maximum and minimum temperatures in Jinan in recent 60 years were analyzed.The historical evolution trend and decadal variation characteristics were discussed.[Result] Winter average,maximum and minimum temperatures in Jinan in recent 60 years all presented slow fluctuation rise trend.The rise trend was obvious.Especially the increase amplitude of minimum temperature was the maximum.It illustrated that the variation of minimum temperature was more sensitive than that of maximum temperature,and the climatic warming in winter was mainly from the contribution of minimum temperature rise.Seen from the decadal variation,cold winter mainly appeared before the 1970s.Then,it presented obvious decrease trend.Conversely,warm winter presented increase trend after the 1970s.Warm winter phenomenon slowed after 2000.Winter temperature presented stepped warming trend during 1950s-1990s.Winter average temperature presented jumped warming trend when entered into the 1990s.The temperature presented downward trend when entered into the 21st century.But winter temperature still presented rise trend as a whole.The population growth in Jinan made that urbanization process accelerated,and urban heat island effect aggravated.It was one of important factors for climate warming in Jinan.[Conclusion] The research provided theoretical basis for understanding the long-term variation trend of climate in Jinan area,and if it was consistent with the background of global climatic warming.展开更多
[Objective] The research aimed to study the short-time forecast method of winterminimum temperature in the northern area of Fujian.[Method] By analyzing the variation trends and distribution characteristics of extreme...[Objective] The research aimed to study the short-time forecast method of winterminimum temperature in the northern area of Fujian.[Method] By analyzing the variation trends and distribution characteristics of extremely and averageminimum temperatures in northern Fujian in winter during 1969-2008,the relative meteorological factors which affected the low temperature weather in winter were found.The influences of relative meteorological factors on winterminimum temperature and the forecast method were summarized by combining with the climate characteristics in northern Fujian.[Result] Winterminimum temperature in Guangze and Pucheng in the north of northern Fujian was the lowest.The second one was in Shaowu,Wuyishan,Jianyang,Songxi and Zhenghe.Theminimum temperature in Jian’ou and Shunchang was higher and was the highest in Yanping.Theminimum temperature mainly depended on the temperature reduction degree from the afternoon to the night.The temperature reduction degree varied with the sky condition and cold air intensity.The temperature reduction included the advection,radiation,advection-radiation and non-advection-radiation types.The temperature had the different reduction characteristics under the different sky conditions.The forecast ofminimum temperature should be carried out based on the weather typing.Meanwhile,the successful forecast key ofminimum temperature was grasping the shift pathway and speed of cold air.[Conclusion] The research provided the theory basis for improving the forecast accuracy of winterminimum temperature.展开更多
[Objective] The study aimed to discuss the influence of light and temperature factors on biomass accumulation of winter wheat at each growth stage and changes in biomass of each organ. [Method] Based on the observatio...[Objective] The study aimed to discuss the influence of light and temperature factors on biomass accumulation of winter wheat at each growth stage and changes in biomass of each organ. [Method] Based on the observation data from Xifeng Agrometeorological Experiment Station of Gansu Province, including phenophase and yield factors of winter wheat in 1981 -2008, biomass at three-leaves, overwintering, jointing, heading, milky maturity, and maturity stages in 1995 -2008, and meteorological data in 1995 -2008, the variation patterns of the biomass accumulation and the influence of TEP (thermal effectiveness photosynthetically active radiation) on the biomass of winter wheat at every growth stage were ana- lyzed. [Result] The biomass accumulation of winter wheat in the whole growth period presented "S" curve, with the maximum value from heading to milky maturity stage. Since 1981, TEP from heading to milky maturity stage increased with a rate of 3. 314 MJ/(m2 · a), and the changing curves of TEP at other stages were like parable curves. TEP from turning green to jointing stage and from milky maturity to maturity stage had a higher value in the 1990s and a lower val.ue in the 1980s and early 21st century, while that from jointing to heading stage had a lower value in the 1990s but a higher value in the 1980s and early 21st century. There was a significant correlation between TEP at each growth stage and the actual yield. LAI (leaf area index) at each development stage also had a significant correlation with the utilization rate of TEP at corresponding stage. When LAI at jointing and heading stages increased by I, the utilization rate of TEP correspondingly increased by 0. 049 and 0.259 g/MJ respectively. [ Conclusion] The research could provide theoretical references for the scientific planting and management of winter wheat in future. Key words Light and temperature factors; Winter wheat; Biomass; Influence; China展开更多
The present study defines a low-latitude component (regionally averaged winter 1000-hPa V-winds over 10 25°N, 105 135°E) and a mid-high-latitude component (regionally averaged winter 1000-hPa V-winds over 30...The present study defines a low-latitude component (regionally averaged winter 1000-hPa V-winds over 10 25°N, 105 135°E) and a mid-high-latitude component (regionally averaged winter 1000-hPa V-winds over 30 50°N, 110 125°E) of the East Asian winter monsoon (EAWM), which are denoted as EAWM-L and EAWM-M, respectively. The study examines the variation characteristics, reflecting variations in winter climate over eastern China, and associated atmospheric circulations corresponding to the two components. The main results are as follows: 1) the EAWM-L and EAWM-M have consistent variation in some years but opposite variations in other years; 2) the EAWM-M index mainly reflects the extensive temperature variability over eastern China, while the EAWM-L index better reflects the variation in winter precipitation over most parts of eastern China; and 3) corresponding to the variation in the EAWM-M index, anomalous winds over the mid-high latitudes of East Asia modulate the southward invasion of cold air from the high latitudes and accordingly affect temperatures over eastern China. In combination with the variation in the EAWM-L index, anomalous low-latitudinal winds regulate the water vapor transport from tropical oceans to eastern China, resulting in anomalous winter precipitation. These pronounced differences between the EAWM-L and the EAWM-M suggest that it is necessary to explore the monsoons' individual features and effects in the EAWM study.展开更多
This study identifies a decadal shift of summer surface air temperature (SAT) over Northeast Asia,including southeastern parts of Russia,Mongolia and northern China,around the mid-1990s.The results suggest that the ...This study identifies a decadal shift of summer surface air temperature (SAT) over Northeast Asia,including southeastern parts of Russia,Mongolia and northern China,around the mid-1990s.The results suggest that the SAT over the Northeast Asia experienced a significant warming after 1994 relative to that before 1993.This decadal shift also extends to northern China,and leads to a warmer summer over Northeast China and North China after the mid-1990s.The decadal warming over Northeast Asia is found to concur with the enhancement of South China rainfall around the mid-1990s.On the one hand,both the Northeast Asian SAT and South China rainfall exhibit this mid-1990s decadal shift only in summer,but not in other seasons.On the other hand,both the Northeast Asian SAT and South China rainfall exhibit this mid-1990s decadal shift not only in the summer seasonal mean,but also in each month of summer (June,July and August).Furthermore,the decadal warming is found to result from an anticyclonic anomaly over Northeast Asia,which can be interpreted as the response to the increased precipitation over South China,according to previous numerical results.Thus,we conclude that the warming shift of summer Northeast Asian SAT around the mid-1990s was a remote response to the increased precipitation over South China.展开更多
Drought monitoring is the base for drought coping and adaptation. Xingtai is located in North China's key winter wheat production areas where drought is severe and frequent. The rainfall during winter wheat growing s...Drought monitoring is the base for drought coping and adaptation. Xingtai is located in North China's key winter wheat production areas where drought is severe and frequent. The rainfall during winter wheat growing season is just about 1/3 of total demand. Xingtai has typical mountainous, hilly and plain agricultural zones, compound rain-fed and irrigated farming patterns. The winter wheat irrigation has heavily depended on overdraw of groundwater in recent decades. In the study, the MODIS (Moderate-Resolution Imaging Spectroradiometer) images taken at the key winter wheat growing season (Mar. to May) in normal rainfall year (2006) were selected, extracted NDVI (Normalized Difference Vegetation Index) and LST (Land Surface Temperature) data, calculated TVDI (Temperature and Vegetation Drought Index), classified and mapped winter wheat drought intensity. Further, based on TVDI, a CDRA (Comprehensive Drought Risk Assessment) model for winter wheat drought disaster risk assessment was constructed and zoning was made. Verified by winter wheat yield, the risk zoning by CDRA is consistent with actual crop failure space. This method can be used in drought risk management.展开更多
The variation of winter snowfall intensity over Northeast China and its relationship with the autumn North Pacific SST are investigated for the period 1960–2012. An upward trend is apparent for the winter snowfall in...The variation of winter snowfall intensity over Northeast China and its relationship with the autumn North Pacific SST are investigated for the period 1960–2012. An upward trend is apparent for the winter snowfall intensity over Northeast China during the last half-century, coinciding with an increasing autumn SST over the North Pacific. Their interannual correlation coefficient reaches up to 0.58 for the past five decades, and 0.42 after their trends are removed. Further analyses indicate that the warming SST during autumn may persist into winter. Correspondingly, large parts of East Asia and the North Pacific are dominated by an anticyclonic anomaly, which can induce an anomalous southeasterly over Northeast China, weaken the northerly wind, then warm the surface, increase the water vapor content and intensify snowfall events. Thus, the autumn North Pacific SST can be considered as a key predictor for winter snowfall events over Northeast China. Results from leaveone-out cross-validation and independent validation both show a significant correlation and a small RMSE between prediction and observation. Therefore, the autumn SST over the North Pacific is suggested as a potential predictor for winter snowfall intensity in Northeast China.展开更多
An operational ocean circulation-surface wave coupled forecasting system for the seas off China and adjacent areas(OCFS-C) is developed based on parallelized circulation and wave models. It has been in operation sin...An operational ocean circulation-surface wave coupled forecasting system for the seas off China and adjacent areas(OCFS-C) is developed based on parallelized circulation and wave models. It has been in operation since November 1, 2007. In this paper we comprehensively present the simulation and verification of the system, whose distinguishing feature is that the wave-induced mixing is coupled in the circulation model. In particular, with nested technique the resolution in the China's seas has been updated to(1/24)° from the global model with(1/2)°resolution. Besides, daily remote sensing sea surface temperature(SST) data have been assimilated into the model to generate a hot restart field for OCFS-C. Moreover, inter-comparisons between forecasting and independent observational data are performed to evaluate the effectiveness of OCFS-C in upper-ocean quantities predictions, including SST, mixed layer depth(MLD) and subsurface temperature. Except in conventional statistical metrics, non-dimensional skill scores(SS) is also used to evaluate forecast skill. Observations from buoys and Argo profiles are used for lead time and real time validations, which give a large SS value(more than 0.90). Besides, prediction skill for the seasonal variation of SST is confirmed. Comparisons of subsurface temperatures with Argo profiles data indicate that OCFS-C has low skill in predicting subsurface temperatures between 100 m and 150 m. Nevertheless, inter-comparisons of MLD reveal that the MLD from model is shallower than that from Argo profiles by about 12 m, i.e., OCFS-C is successful and steady in MLD predictions. Validation of 1-d, 2-d and 3-d forecasting SST shows that our operational ocean circulation-surface wave coupled forecasting model has reasonable accuracy in the upper ocean.展开更多
A new circulation index(ISW) that can realistically describe winter temperature variations over Southwest China is defined based on analysis of the NCEP/NCAR reanalysis data(version 1) and the observations at585 s...A new circulation index(ISW) that can realistically describe winter temperature variations over Southwest China is defined based on analysis of the NCEP/NCAR reanalysis data(version 1) and the observations at585 stations in China. The study period is from January 1961 to February 2011. The relationship between ISW and general circulation patterns in East Asia is also analyzed. Results show that ISW successfully captures the variations in winter temperature over Southwest China. High ISW values correspond to the intensified Mongolian high, the weakened Aleutian low, increases in the strength of the Middle East westerly jet stream over the south of the Tibetan Plateau(TP), and decreases in the strength of the subtropical westerly jet over the north of the TP. Meanwhile, the East Asian trough deepens and extends southwestward,making it easier for the cold air mass from the north to intrude Southwest China along the trough. These circulation patterns lead to a decrease in winter temperature over Southwest China(and vice versa). In addition to the East Asian winter monsoon, the two westerly jets that dominate the upper level circulation over East Asia also exert important influences on winter temperature in Southwest China, especially the Middle East westerly jet to the south of the TP.展开更多
基金Under the auspices of the Social Science and Humanity on Young Fund of the Ministry of Education of China(No.21YJCZH100)the Scientific Research Project on Outstanding Young of the Fujian Agriculture and Forestry University(No.XJQ201920)+1 种基金the Science and Technology Innovation Special Fund Project of Fujian Agriculture and Forestry University(No.CXZX2021032)the Forestry Peak Discipline Construction Project of Fujian Agriculture and Forestry University(No.72202200205)。
文摘Under the influence of anthropogenic and climate change,the problems caused by urban heat island(UHI)has become increasingly prominent.In order to promote urban sustainable development and improve the quality of human settlements,it is significant for exploring the evolution characteristics of urban thermal environment and analyzing its driving forces.Taking the Landsat series images as the basic data sources,the winter land surface temperature(LST)of the rapid urbanization area of Fuzhou City in China was quantitatively retrieved from 2001 to 2021.Combing comprehensively the standard deviation ellipse model,profile analysis and GeoDetector model,the spatio-temporal evolution characteristics and influencing factors of the winter urban thermal environment were systematically analyzed.The results showed that the winter LST presented an increasing trend in the study area during 2001–2021,and the winter LST of the central urban regions was significantly higher than the suburbs.There was a strong UHI effect from 2001 to 2021with an expansion trend from the central urban regions to the suburbs and coastal areas in space scale.The LST of green lands and wetlands are significantly lower than croplands,artificial surface and unvegetated lands.Vegetation and water bodies had a significant mitigation effect on UHI,especially in the micro-scale.The winter UHI had been jointly driven by the underlying surface and socio-economic factors in a nonlinear or two-factor interactive enhancement mode,and socio-economic factors had played a leading role.This research could provide data support and decision-making references for rationally planning urban layout and promoting sustainable urban development.
基金supported by the Major State Basic Research Development Program of China (973 Program) under grant No.2009CB421406the Research Program for excellent Ph. D dissertations in the Chinese Academy of Sciences
文摘The author investigates the prediction of Northeast China's winter surface air temperature (SAT),and first forecast the year to year increment in the predic-tand and then predict the predictand.Thus,in the first step,we determined the predictors for an increment in winter SAT by analyzing the atmospheric variability associated with an increment in winter SAT.Then,multi-linear re-gression was applied to establish a prediction model for an increment in winter SAT in Northeast China.The pre-diction model shows a high correlation coefficient (0.73) between the simulated and observed annual increments in winter SAT in Northeast China throughout the period 1965-2002,with a relative root mean square error of -7.9%.The prediction model makes a reasonable hindcast for 2003-08,with an average relative root mean square error of -7.2%.The prediction model can capture the in-creasing trend of winter SAT in Northeast China from 1965-2008.The results suggest that this approach to forecasting an annual increment in winter SAT in North-east China would be relevant in operational seasonal forecasts.
基金supported by the National Natural Science Foundation of China(Grant Nos.41130103 and 41210007)the National Basic Research Program of China(Grant No.2009CB421406)the CAS–CSIRO Cooperative Research Program(Grant No.GJHZ1223)
文摘This paper addresses the interannual variation of winter air temperature over Northeast China and its connection to preceding Eurasian snow cover. The results show that there is a significant negative correlation between October Eurasian snow cover and following-winter air temperature over Northeast China. The snow cover located in eastern Siberia and to the northeast of Lake Baikal plays an important role in the winter air temperature anomaly. More (less) eastern Siberia snow in October can cause an atmospheric circulation anomaly pattern in which the atmospheric pressure is higher (lower) than normal in the polar region and lower (higher) in the northern mid-high latitudes. Due to the persistence of the eastern Siberia snow from October to the following winter, the winter atmospheric anomaly is favorable (unfavorable) to the widespread movement of cold air masses from the polar region toward the northern mid-high latitudes and, hence, lower (higher) temperature over Northeast China. Simultaneously, when the October snow cover is more (less), the SST in the northwestern Pacific is continuously lower (higher) as a whole; then, the Aleutian low and the East Asia trough are reinforced (weakened), favoring the lower (higher) temperature over Northeast China.
基金jointly supported by the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.KZCX2-YW-QN202)the National Basic Research Program of China(Grant Nos.2010CB9503042 and 2009CB421406)strategic technological program of the Chinese Academy of Sciences(Grant No.XDA05090426)
文摘This paper presents a statistical scheme for the seasonal forecasting of North China's surface air temperature (NCSAT) during winter. Firstly, a prediction model for an decrease or increase of winter NCSAT is established, whose predictors are available for no later than the previous September, as this is the most favorable month for seasonal forecasting up to two months ahead.The predicted NCSAT is then derived as the sum of the predicted increment of NCSAT and the previous NCSAT. The scheme successfully predicts the interannual and the decadal variability of NCSAT. Additionally, the advantages of the prediction scheme are discussed.
基金supported jointly by the strategic technological program of the Chinese Academy of Sciences(Grant No.XDA05090405)the National Basic Research Program of China(Grant Nos.2009CB421406 and 2010CB950304)+1 种基金the Special Fund for the Public Welfare Industry(MeteorologyGrant Nos.GYHY201006022 and GYHY200906018)
文摘The winter temperature changes in East China during the past 100 years are investigated by using the Twentieth Century Version 2(20th-v2)Reanalysis.Four typical warm(P1,1911–30;P4,1991–2010)and cold(P2,1938–57;P3,1961–80)periods are identified for the East China winter temperature index.Comparison of160-station observational data,NCAR sea level pressure(SLP)data,and NCEP/NCAR Reanalysis shows that the20th-v2 Reanalysis can successfully depict the major features of the warming from P3 to P4,which is part of the global warming phenomenon.The cooling from P1 to P2is a regional phenomenon under global warming.However,both changes are consistent with the phase change of the Arctic Oscillation(AO),while the second change is also accompanied by the phase change of Antarctic Oscillation(AAO)from negative to positive.Original sources of the interdecadal shifts of the AO and winter temperature in East China require further research.
文摘[Objective] The research aimed to study the distribution characteristics of winter continuous extreme low temperature in China. [Method] Based on the daily minimum temperature data in winter during 1961-2008 in 195 observatories, the continuous extreme low temperature event (cold night) which happened in winter in China and the distribution characteristics of accumulated temperature anomaly in 48 years were analyzed by using the actual probability distribution threshold method. [Result] Besides in Northeast China, Northwest China and Qinghai-Tibet Plateau where the geographical position was northerly, and the altitude was high, the long-time (above 5 d) extreme low temperature event was also easy to happen in the south of Yangtze River, especially in Guizhou, Guangxi, Hunan and so on. The continuous extreme low temperature event in the middle and lower reaches of Yellow River was the least. Started from the metaphase of the 1980s, the frequency trend of continuous extreme low temperature event decreased. But in 1992, 2000 and 2007, the low temperature event which continued above 7 d was more than the average. The accumulated cold in January in 48 years was the strongest. The second one was in February, and the smallest was in December. The accumulated cold in Northeast China and the north of Inner Mongolia was the biggest in December and January. The accumulated cold in the north of Xinjiang was the biggest in February. In the whole winter, the accumulated cold in Qinghai-Tibet Plateau was the smallest. The chilling injury was easier to happen in Guizhou, Guangxi and Hunan than other south areas in December and February. The occurrence probability of chilling injury in most areas of Szechwan Basin, Yunnan and Qinling Mountains in central China was smaller than that in other areas. [Conclusion] The research provided the reference basis for analyzing the influence of chilling injury on the agriculture in China.
基金the support of the National Natural Science Foundation of China (Grant Nos. 41375090 and 41375089)the Basic Research Fund of the Chinese Academy of Meteorological Sciences (Grant No. 2013Z002)
文摘Based on monthly mean surface air temperature (SAT) from 71 stations in northern China and NCEP/ NCAR and NOAA-CIRES (Cooperative Institute for Research in Environmental Sciences) twentieth century reanalysis data, the dominant modes of winter SAT over northem China were explored. The results showed that there are two modes that account for a majority of the total variance over northern China. The first mode is unanimously colder (warmer) over the whole of northern China. The second mode is characterized by a dipole structure that is colder (warmer) over Northwest China (NWC) and warmer (colder) over Northeast China (NEC), accounting for a fairly large proportion of the total variance. The two components constituting the second mode, the individual variations of winter SAT over NWC and NEC and their respective preceding factors, were further investigated. It was found that the autumn SAT anomalies are closely linked to persistent snow cover anomalies over Eurasia, showing the delayed effects on winter climate over northern China. Specifically, the previous autumn SAT anomalies over the Lake Baikal (LB; 50-60°N, 85-120°E) and Mongolian Plateau (MP; 42-52°N, 80-120°E) regions play an important role in adjusting the variations of winter SAT over NWC and NEC, respectively. The previous autumn SAT anomaly over the MP region may exert an influence on the winter SAT over NEC through modulating the strength and location of the East Asian major trough. The previous autumn SAT over the LB region may modulate winter westerlies at the middle and high latitudes of Asia and accordingly affects the invasion of cold air and associated winter SAT over NWC.
文摘We extracted 374 pieces of records of frost date from historical documents. Using these records, we reconstructed winter half-year (October to next April) temperature series, with a resolution of 5-year, for the North China Plain during 1651-2010. The results show that the temperature changes in the North China Plain were divided into four phases. With the reference period of 1951-1980, two cold phases, 1651-1700 and 1781-1900, have cold anomaly of 0.83°C and 0.60°C respectively. However, between the two cold phases, 1701-1780 was a relative warm phase with the cold anomaly of 0.36°C referring to the mean of 1951-1980. After the 1900, the climate came into a warm phase. The mean temperature of 1901-2010 was 0.11°C higher than the mean of 1951-1980. During 1651-2010, the 1996-2000 is the warmest 5-year with the warm anomaly of 1.25°C than that of the reference period of 1951-1980.
基金Supported by the Special Project for Climate Change of China Meteorological Administration(CCSF201234)
文摘[Objective] The study aimed to discuss the relationship between temperature variation in winter of China and arctic oscillation. [Method] By using the NCEP/NCAR reanalysis data, AO index series and monthly temperature data from 160 stations of China, the variation characteris- tics of temperature in winter and AO index series as well as their relationship from 1951 to 2007 were studied. [Result] Temperature in winter of Chi- na correlated positively with AO index series. Both arctic oscillation and winter temperature in China had two major periods of 8 and 18 years. ⅠWTr and ⅠAO series, which had obvious inter-annual and inter-decadal variations, presented the almost same rising trend and had close relationship on an inter-decadal scale. Compared with AO, the Siberia high had more distinguished influences on inter-annual variations of temperature in winter of China. AO might affect changes in the Siberian high and thereby influence temperature in winter of China. AO had a greater influence on tempera- ture in winter of China than the Siberia high on an inter-decadal scale. When the East Asian through was weak, temperature in winter of China and AO index were low, while they were high as it was strong. The impact of AO index on an inter-decadal scale was more significant than the impact on an inter-annual scale. [ Condusien] The research could make the effects of AO on winter temperature of China clear.
文摘Using NCEP/NCAR R2 reanalysis daily data and daily meteorologicalobservational data of southwest China in 2010, this paper studied the submonthlytimescale oscillation characteristics of the East Asian winter monsoon (EAWM) and itseffect on the temperature of southwest China in 2010 by bandpass filtering, wavelettransformation, composite analysis and correlation analysis. The main conclusions areas follows: The EAWM in 2010 was dominated by low-frequency oscillations of about 7-,12-, and 30-day periods. There existed obviously negative correlation between theEAWM and the winter temperature in southwest China on submonthly, quasi-weeklyand quasi-biweekly timescales, and negative correlation was more obvious on thequasi-biweekly than the quasi-weekly timescale. There was significant difference in thedistribution of high, middle and low layer of the troposphere when the EAWM was onthe submonthly, quasi-one-week and quasi-two-week timescales in the positive andnegative phase. In the positive EAWM phase, the upper-level subtropical westerly jet isstronger and the East Asia trough is deeper, thus it is favorable for the dominance ofmore powerful north wind and lower temperature in southwest China. On the contrary,in the negative EAWM phase, the upper-level subtropical westerly jet is weaker and theEast Asia trough is shallower, thus unfavorable for the north wind and lowertemperature in southwest China.
基金The Strategic Priority Research Program of Chinese Academy of Sciences under contract No. XDA05090404Open Fund of the key Laboratory of Ocean Circulation and Waves,Chinese Academy of Scineces under No. KLOCAW1201The Knowledge Innovation Program of Chinese Academy of Sciences under contract Nos KZCX1-YW-12 and KZCX2-YW-Q11-02
文摘The global surface temperature change since the mid-19th century has caused general concern and intensive study. However, long-term changes in the marginal seas, including the seas east of China, are not well understood because long-term observations are sparse and, even when they exist, they are over limited areas. Preliminary results on the long-term variability of sea surface temperature (SST) in summer and winter in the seas east of China during the period of 1957-2001 are reported using the Ocean Science Database of Institute of Oceanology, Chinese Academy of Sciences, the coastal hydrological station in situ and satellite data. The results show well-defined warming trends in the study area. However warming and cooling trends vary from decade to decade, with steady and rapid warming trends after the 1980s and complicated spatial patterns. The distribution of SST variation is intricate and more blurred in the areas far away from the Kuroshio system. Both historical and satellite data sets show significant warming trends after 1985. The warming trends are larger and spread to wider areas in winter than in summer, which means decrease in the seasonal cycle of SST probably linked with recently observed increase of the tropical zooplankton species in the region. Spatial structures of the SST trends are roughly consistent with the circulation pattern especially in winter when the meridional SST gradients are larger, suggesting that a horizontal advection may play an important role in the long-term SST variability in winter.
基金Supported by Special Item of Climate Variation of China Meteorological Administration ( CCFS-11-4)
文摘[Objective] The research aimed to study the variation characteristics of winter temperature in Jinan in recent 60 years.[Method] Based on winter monthly average,maximum and minimum temperatures in the ground observation station of Jinan during 1951-2010,by using linear trend,5-year moving average and anomaly,the variation characteristics of winter average,maximum and minimum temperatures in Jinan in recent 60 years were analyzed.The historical evolution trend and decadal variation characteristics were discussed.[Result] Winter average,maximum and minimum temperatures in Jinan in recent 60 years all presented slow fluctuation rise trend.The rise trend was obvious.Especially the increase amplitude of minimum temperature was the maximum.It illustrated that the variation of minimum temperature was more sensitive than that of maximum temperature,and the climatic warming in winter was mainly from the contribution of minimum temperature rise.Seen from the decadal variation,cold winter mainly appeared before the 1970s.Then,it presented obvious decrease trend.Conversely,warm winter presented increase trend after the 1970s.Warm winter phenomenon slowed after 2000.Winter temperature presented stepped warming trend during 1950s-1990s.Winter average temperature presented jumped warming trend when entered into the 1990s.The temperature presented downward trend when entered into the 21st century.But winter temperature still presented rise trend as a whole.The population growth in Jinan made that urbanization process accelerated,and urban heat island effect aggravated.It was one of important factors for climate warming in Jinan.[Conclusion] The research provided theoretical basis for understanding the long-term variation trend of climate in Jinan area,and if it was consistent with the background of global climatic warming.
文摘[Objective] The research aimed to study the short-time forecast method of winterminimum temperature in the northern area of Fujian.[Method] By analyzing the variation trends and distribution characteristics of extremely and averageminimum temperatures in northern Fujian in winter during 1969-2008,the relative meteorological factors which affected the low temperature weather in winter were found.The influences of relative meteorological factors on winterminimum temperature and the forecast method were summarized by combining with the climate characteristics in northern Fujian.[Result] Winterminimum temperature in Guangze and Pucheng in the north of northern Fujian was the lowest.The second one was in Shaowu,Wuyishan,Jianyang,Songxi and Zhenghe.Theminimum temperature in Jian’ou and Shunchang was higher and was the highest in Yanping.Theminimum temperature mainly depended on the temperature reduction degree from the afternoon to the night.The temperature reduction degree varied with the sky condition and cold air intensity.The temperature reduction included the advection,radiation,advection-radiation and non-advection-radiation types.The temperature had the different reduction characteristics under the different sky conditions.The forecast ofminimum temperature should be carried out based on the weather typing.Meanwhile,the successful forecast key ofminimum temperature was grasping the shift pathway and speed of cold air.[Conclusion] The research provided the theory basis for improving the forecast accuracy of winterminimum temperature.
基金Supported by the Arid Meteorology Foundation of Institute of Arid Meteorology,China Meteorological Administration(IAM200803)
文摘[Objective] The study aimed to discuss the influence of light and temperature factors on biomass accumulation of winter wheat at each growth stage and changes in biomass of each organ. [Method] Based on the observation data from Xifeng Agrometeorological Experiment Station of Gansu Province, including phenophase and yield factors of winter wheat in 1981 -2008, biomass at three-leaves, overwintering, jointing, heading, milky maturity, and maturity stages in 1995 -2008, and meteorological data in 1995 -2008, the variation patterns of the biomass accumulation and the influence of TEP (thermal effectiveness photosynthetically active radiation) on the biomass of winter wheat at every growth stage were ana- lyzed. [Result] The biomass accumulation of winter wheat in the whole growth period presented "S" curve, with the maximum value from heading to milky maturity stage. Since 1981, TEP from heading to milky maturity stage increased with a rate of 3. 314 MJ/(m2 · a), and the changing curves of TEP at other stages were like parable curves. TEP from turning green to jointing stage and from milky maturity to maturity stage had a higher value in the 1990s and a lower val.ue in the 1980s and early 21st century, while that from jointing to heading stage had a lower value in the 1990s but a higher value in the 1980s and early 21st century. There was a significant correlation between TEP at each growth stage and the actual yield. LAI (leaf area index) at each development stage also had a significant correlation with the utilization rate of TEP at corresponding stage. When LAI at jointing and heading stages increased by I, the utilization rate of TEP correspondingly increased by 0. 049 and 0.259 g/MJ respectively. [ Conclusion] The research could provide theoretical references for the scientific planting and management of winter wheat in future. Key words Light and temperature factors; Winter wheat; Biomass; Influence; China
基金supported by the National Key Technologies R&D Program of China (Grant No.2009BAC51B02)the Basic Research Fund of Chinese Academy of Meteorological Sciences (CAMS) (Grant No. 2010Z001)the Innovative Research Team Construction Program of CAMS (Grant No. 2010Z003)
文摘The present study defines a low-latitude component (regionally averaged winter 1000-hPa V-winds over 10 25°N, 105 135°E) and a mid-high-latitude component (regionally averaged winter 1000-hPa V-winds over 30 50°N, 110 125°E) of the East Asian winter monsoon (EAWM), which are denoted as EAWM-L and EAWM-M, respectively. The study examines the variation characteristics, reflecting variations in winter climate over eastern China, and associated atmospheric circulations corresponding to the two components. The main results are as follows: 1) the EAWM-L and EAWM-M have consistent variation in some years but opposite variations in other years; 2) the EAWM-M index mainly reflects the extensive temperature variability over eastern China, while the EAWM-L index better reflects the variation in winter precipitation over most parts of eastern China; and 3) corresponding to the variation in the EAWM-M index, anomalous winds over the mid-high latitudes of East Asia modulate the southward invasion of cold air from the high latitudes and accordingly affect temperatures over eastern China. In combination with the variation in the EAWM-L index, anomalous low-latitudinal winds regulate the water vapor transport from tropical oceans to eastern China, resulting in anomalous winter precipitation. These pronounced differences between the EAWM-L and the EAWM-M suggest that it is necessary to explore the monsoons' individual features and effects in the EAWM study.
基金supported by the National Natural Science Foundation of China (Grant No. 41105046)the National Basic Research Program of China (Grant No. 2010CB950403)the Chinese Academy of Sciences (Grant No. XDA05090000)
文摘This study identifies a decadal shift of summer surface air temperature (SAT) over Northeast Asia,including southeastern parts of Russia,Mongolia and northern China,around the mid-1990s.The results suggest that the SAT over the Northeast Asia experienced a significant warming after 1994 relative to that before 1993.This decadal shift also extends to northern China,and leads to a warmer summer over Northeast China and North China after the mid-1990s.The decadal warming over Northeast Asia is found to concur with the enhancement of South China rainfall around the mid-1990s.On the one hand,both the Northeast Asian SAT and South China rainfall exhibit this mid-1990s decadal shift only in summer,but not in other seasons.On the other hand,both the Northeast Asian SAT and South China rainfall exhibit this mid-1990s decadal shift not only in the summer seasonal mean,but also in each month of summer (June,July and August).Furthermore,the decadal warming is found to result from an anticyclonic anomaly over Northeast Asia,which can be interpreted as the response to the increased precipitation over South China,according to previous numerical results.Thus,we conclude that the warming shift of summer Northeast Asian SAT around the mid-1990s was a remote response to the increased precipitation over South China.
基金The study was supported by the National Natural Science Foundation of China [No.46171501 ].
文摘Drought monitoring is the base for drought coping and adaptation. Xingtai is located in North China's key winter wheat production areas where drought is severe and frequent. The rainfall during winter wheat growing season is just about 1/3 of total demand. Xingtai has typical mountainous, hilly and plain agricultural zones, compound rain-fed and irrigated farming patterns. The winter wheat irrigation has heavily depended on overdraw of groundwater in recent decades. In the study, the MODIS (Moderate-Resolution Imaging Spectroradiometer) images taken at the key winter wheat growing season (Mar. to May) in normal rainfall year (2006) were selected, extracted NDVI (Normalized Difference Vegetation Index) and LST (Land Surface Temperature) data, calculated TVDI (Temperature and Vegetation Drought Index), classified and mapped winter wheat drought intensity. Further, based on TVDI, a CDRA (Comprehensive Drought Risk Assessment) model for winter wheat drought disaster risk assessment was constructed and zoning was made. Verified by winter wheat yield, the risk zoning by CDRA is consistent with actual crop failure space. This method can be used in drought risk management.
基金jointly supported by the National Basic Research Program of China[grant number 2012CB955401]National Natural Science Foundation of China[grant numbers 41305061 and 41210007]
文摘The variation of winter snowfall intensity over Northeast China and its relationship with the autumn North Pacific SST are investigated for the period 1960–2012. An upward trend is apparent for the winter snowfall intensity over Northeast China during the last half-century, coinciding with an increasing autumn SST over the North Pacific. Their interannual correlation coefficient reaches up to 0.58 for the past five decades, and 0.42 after their trends are removed. Further analyses indicate that the warming SST during autumn may persist into winter. Correspondingly, large parts of East Asia and the North Pacific are dominated by an anticyclonic anomaly, which can induce an anomalous southeasterly over Northeast China, weaken the northerly wind, then warm the surface, increase the water vapor content and intensify snowfall events. Thus, the autumn North Pacific SST can be considered as a key predictor for winter snowfall events over Northeast China. Results from leaveone-out cross-validation and independent validation both show a significant correlation and a small RMSE between prediction and observation. Therefore, the autumn SST over the North Pacific is suggested as a potential predictor for winter snowfall intensity in Northeast China.
基金China-Korea Cooperation Project on the development of oceanic monitoring and prediction system on nuclear safetythe Project of the National Programme on Global Change and Air-sea Interaction under contract No.GASI-03-IPOVAI-05
文摘An operational ocean circulation-surface wave coupled forecasting system for the seas off China and adjacent areas(OCFS-C) is developed based on parallelized circulation and wave models. It has been in operation since November 1, 2007. In this paper we comprehensively present the simulation and verification of the system, whose distinguishing feature is that the wave-induced mixing is coupled in the circulation model. In particular, with nested technique the resolution in the China's seas has been updated to(1/24)° from the global model with(1/2)°resolution. Besides, daily remote sensing sea surface temperature(SST) data have been assimilated into the model to generate a hot restart field for OCFS-C. Moreover, inter-comparisons between forecasting and independent observational data are performed to evaluate the effectiveness of OCFS-C in upper-ocean quantities predictions, including SST, mixed layer depth(MLD) and subsurface temperature. Except in conventional statistical metrics, non-dimensional skill scores(SS) is also used to evaluate forecast skill. Observations from buoys and Argo profiles are used for lead time and real time validations, which give a large SS value(more than 0.90). Besides, prediction skill for the seasonal variation of SST is confirmed. Comparisons of subsurface temperatures with Argo profiles data indicate that OCFS-C has low skill in predicting subsurface temperatures between 100 m and 150 m. Nevertheless, inter-comparisons of MLD reveal that the MLD from model is shallower than that from Argo profiles by about 12 m, i.e., OCFS-C is successful and steady in MLD predictions. Validation of 1-d, 2-d and 3-d forecasting SST shows that our operational ocean circulation-surface wave coupled forecasting model has reasonable accuracy in the upper ocean.
基金Supported by the National Natural Science Foundation of China(41375089)
文摘A new circulation index(ISW) that can realistically describe winter temperature variations over Southwest China is defined based on analysis of the NCEP/NCAR reanalysis data(version 1) and the observations at585 stations in China. The study period is from January 1961 to February 2011. The relationship between ISW and general circulation patterns in East Asia is also analyzed. Results show that ISW successfully captures the variations in winter temperature over Southwest China. High ISW values correspond to the intensified Mongolian high, the weakened Aleutian low, increases in the strength of the Middle East westerly jet stream over the south of the Tibetan Plateau(TP), and decreases in the strength of the subtropical westerly jet over the north of the TP. Meanwhile, the East Asian trough deepens and extends southwestward,making it easier for the cold air mass from the north to intrude Southwest China along the trough. These circulation patterns lead to a decrease in winter temperature over Southwest China(and vice versa). In addition to the East Asian winter monsoon, the two westerly jets that dominate the upper level circulation over East Asia also exert important influences on winter temperature in Southwest China, especially the Middle East westerly jet to the south of the TP.