[Objective] To provide a theoretical basis for high-yield breeding of broom sorghum.[Method] Using 11 kinds of broom sorghum collected at home as research objects, the differences in morphological characteristics of b...[Objective] To provide a theoretical basis for high-yield breeding of broom sorghum.[Method] Using 11 kinds of broom sorghum collected at home as research objects, the differences in morphological characteristics of broom sorghum were compared through the survey of some indicators, such as plant height, tillering, inflorescence, stem node, stem-leaf ratio, yield, and so on. [Result] The 11 kinds of broom sorghum were different in morphological characteristics with large amplitude of plant height; zygl-1, zygl-6, zygl-8 and zygl-9 were appropriate for fixed broom type; zygl-9 had the highest integrated production. [Condusion] The study laid the foundation for further exploring breeding, cultivation and promotion of broom sorghum.展开更多
The Okinawa Trough is a natural laboratory for the study of air-sea interaction and paleoenvironmental change. It has been demonstrated that present offshore export of particles in the bottom nepheloid layer occur pri...The Okinawa Trough is a natural laboratory for the study of air-sea interaction and paleoenvironmental change. It has been demonstrated that present offshore export of particles in the bottom nepheloid layer occur primarily with downwelling from the northeast winter monsoon, which is inhibited by a transverse circulation pattern in summer. This current system was very different during the Last Glacial Maximum owing to low sea level （-120 m） and exposure of a large shelf area. We collected sediment core Oki01 from the middle Okinawa Trough during 2012 using R/V Kexue No. 1 to elucidate the timing and cause of the current system transition in the East China Sea. Clay mineral, dry density, and elemental （Ti, Ca） composition of core Oki01 was analyzed. The results indicate that clay minerals derived mainly from the Huanghe （Yellow） and the Changjiang （Yangtze） Rivers during 16.0-11.6 ka, and the modem current system in the East China Sea formed beginning in the early Holocene. Therefore, mixing of East China Sea continental shelf, Changjiang River and partially Taiwan Island sediment are the major contributors. The decrease of log（Ti/Ca） and alternating provenance since the early Holocene indicate less sediment from the East China in summer because of resistance of the modern current system, i.e., a ＂water barrier＂ and upwelling. Conversely, sediment delivery persists in winter and log（Ti/Ca） indicates the winter monsoon signal since the early Holocene. Our evidence also suggests that sediment from Taiwan Island could be transported by the Kuroshio Current to the middle Okinawa Trough, where it mingles with winter monsoon- induced export of sediment from the Changjiang River and East China Sea continental shelf. Although the present research advances understanding of the evolutionary history of paleoenvironmental change in the Okinawa Trough, more sediment cores should be retrieved over wide areas to construct a larger scenario.展开更多
In this study, the East Asian summer climate changes under the 1.5 ℃ global warming （1.5 GW） target in 30 simulations derived from 15 coupled models within the Coupled Model Intercomparison Program phase 5 （CMIP5...In this study, the East Asian summer climate changes under the 1.5 ℃ global warming （1.5 GW） target in 30 simulations derived from 15 coupled models within the Coupled Model Intercomparison Program phase 5 （CMIP5） are examined. Compared with the current summer climate （1975-2005）, both surface air temperature and precipitation increase significantly over the East Asian continent during the 1.5 GW period （average period 2021-2051）. In northeastern China this is particularly pronounced with regional averaged precipitation increases of more than 7.2%, which is greater than that for the whole East Asian continent （approximately 4.2%）. Due to stronger enhancement of precipitation north of 40°N, the leading empirical orthogonal function （EOF） mode of summer precipitation over the East Asian continent changes from tripolar-like mode to dipole mode. As there is stronger surface warming over the East Asian continent than that over surrounding ocean, the land-sea thermal contrast is enhanced during the 1.5 GW period. As a result, the monsoon circulation in the lower troposphere is significantly strengthened, which causes the increased summer precipitation over the East Asian continent. In addition, larger interannual variabilities of East Asian summer monsoon circulation and associated precipitation are also suggested for the 1.5 GW period.展开更多
According to the national standard(2006)on tropical cyclone(TC)intensity,TCs are categorized into six intensity types,namely,tropical depression(TD),tropical storm(TS),severe tropical storm(STS), typhoon(TY),severe ty...According to the national standard(2006)on tropical cyclone(TC)intensity,TCs are categorized into six intensity types,namely,tropical depression(TD),tropical storm(TS),severe tropical storm(STS), typhoon(TY),severe typhoon(STY),and super severe typhoon(SSTY).Fifty-eight years(1949–2006)of the datasets from the Yearbook of Typhoons and Yearbook of Tropical Cyclones were used to study the variation characteristics of TCs making landfalls in China's Mainland,Hainan and Taiwan islands.The main results are as follows.First,interannual or interdecadal variations in the number of landfalling TCs at different intensities exist.As far as long-term trends are concerned,the TD and TS frequencies show a significant linearly decreasing trend while those of STY show a significant linearly increasing trend.Second, a significant period of 6–8 years exist in the variations of annual landfalling TD,TS,and STS frequencies while quasi-16-year periods are found in the annual TY frequency.Third,TD and TS are generated mostly over the South China Sea,while TY,STY,and SSTY mostly over the waters southeast of the Bashi Channel and the ocean to the east of the Philippines.Fourth,as far as interdecadal trends are concerned,the frequencies of landfalling TD and TS generated over the South China Sea show significant linearly decreasing trends.However,TY and STY show significant linearly increasing trends.展开更多
The relationship between the intensity of the South China Sea summer monsoon （SCSSM） and the Nino3.4 index and anomalous atmospheric circulation patterns associated with a strong and weak SCSSM are investigated usin...The relationship between the intensity of the South China Sea summer monsoon （SCSSM） and the Nino3.4 index and anomalous atmospheric circulation patterns associated with a strong and weak SCSSM are investigated using the NCEP/NCAR reanalysis data, Extended Reconstructed Sea Surface Temperature （ERSST） data and Climate Prediction Center Merged Analysis of Precipitation （CMAP） data. The SCSSM is significantly positively correlated with the Nino3.4 index in the succeeding northern autumn and winter. In the strong minus weak SCSSM composite, a positive East Asia-Pacific teleconnection （EAP） pattern and a negative Europe-Asian-Pacific teleconnection （EUP） pattern appear in the 500 hPa height difference field; low-level cross-equatorial flows are strengthened over the Maritime Continent （MC） region; positive （negative） precipitation anomalies occur in the South China Sea and western north Pacific （MC）. A possible mechanism through which SCSSM affects ENSO is proposed. A strong （weak） SCSSM strengthens （weakens） cross-equatorial flows over the MC. The anomalous cross-equatorial flows cool （warm） the SST around the MC through enhanced （reduced） surface latent heat fluxes. The cooling （warming） further leads to suppressed （enhanced） convection over the MC, and causes the anomalous westerly （easterly） in the equatorial western Pacific, which favors the onset of E1 Nino （La Nina） through modulating the positive air-sea feedback process.展开更多
We compared nonlinear principal component analysis(NLPCA) with linear principal component analysis(LPCA) with the data of sea surface wind anomalies(SWA),surface height anomalies(SSHA),and sea surface temperature anom...We compared nonlinear principal component analysis(NLPCA) with linear principal component analysis(LPCA) with the data of sea surface wind anomalies(SWA),surface height anomalies(SSHA),and sea surface temperature anomalies(SSTA),taken in the South China Sea(SCS) between 1993 and 2003.The SCS monthly data for SWA,SSHA and SSTA(i.e.,the anomalies with climatological seasonal cycle removed) were pre-filtered by LPCA,with only three leading modes retained.The first three modes of SWA,SSHA,and SSTA of LPCA explained 86%,71%,and 94% of the total variance in the original data,respectively.Thus,the three associated time coefficient functions(TCFs) were used as the input data for NLPCA network.The NLPCA was made based on feed-forward neural network models.Compared with classical linear PCA,the first NLPCA mode could explain more variance than linear PCA for the above data.The nonlinearity of SWA and SSHA were stronger in most areas of the SCS.The first mode of the NLPCA on the SWA and SSHA accounted for 67.26% of the variance versus 54.7%,and 60.24% versus 50.43%,respectively for the first LPCA mode.Conversely,the nonlinear SSTA,localized in the northern SCS and southern continental shelf region,resulted in little improvement in the explanation of the variance for the first NLPCA.展开更多
Lightning is an important natural source of wildfires and oxynitride,and hence significantly influences ecological systems and atmospheric chemistry.Here,we choose South Asia,an important region for global water reall...Lightning is an important natural source of wildfires and oxynitride,and hence significantly influences ecological systems and atmospheric chemistry.Here,we choose South Asia,an important region for global water reallocation and global climate changes,to examine lightning variations based on the longest existing lightning dataset from the OTD/LIS observations.We identify a clear increase in lightning density in the research region,increasing at a rate of 0.096 fl km^(-2)a^(-1)over the last two decades.Multiple linear regression analysis is adopted to identify the main influencing factors among ten potential thermodynamic or microphysical factors and the crucial areas contributing to the increases in lightning.The surface latent heat flux along the west coast of the Indian subcontinent is the largest contributor,explaining52%of the lightning variance and contributing to a 0.025 fl km^(-2)a^(-1)increase.The sea surface temperature in the Arabian Sea,the convective available potential energy(CAPE)over the northwestern Indian subcontinent,and the wind shear along the northwestern coast also make important contributions to the lightning increase,indicating that the thermodynamic effects overwhelm the microphysical effects on lightning activity over the South Asia region.展开更多
Near-inertial motion is an important dynamic process in the upper ocean and plays a significant role in mass, heat, and energy transport across the thermocline. In this study, the dissipation of wind-induced near-iner...Near-inertial motion is an important dynamic process in the upper ocean and plays a significant role in mass, heat, and energy transport across the thermocline. In this study, the dissipation of wind-induced near-inertial energy in the thermocline is investigated by using observation data collected in July and August 2005 during the tropical storm Washi by a moored system at(19°35′N, 112°E) in the continental shelf region off Hainan Island. In the observation period, the near-inertial part dominated the observed ocean kinetic energy and about 80% of the near-inertial energy dissipated in the upper layer. Extremely strong turbulent mixing induced by near-inertial wave was observed in the thermocline, where the turbulent energy dissipation rate increased by two orders of magnitude above the background level. It is found that the energy loss of near-inertial waves in the thermocline is mainly in the large-scales. This is different from the previous hypothesis based on "Kolmogorov cascade" turbulence theory that the kinetic energy is dissipated mainly by small-scale motions.展开更多
Based on a δ180 chronology, rare earth elements （REE） and other typical elements in sediments from core MD06-3047 in the western Philippine Sea were analyzed to constrain the provenances of the sediments and invest...Based on a δ180 chronology, rare earth elements （REE） and other typical elements in sediments from core MD06-3047 in the western Philippine Sea were analyzed to constrain the provenances of the sediments and investigate quantitative changes in the Asian eolian input to the study area over the last 700 ka. Among the competing processes that might affect REE compositions, sediment provenance is the most important one. Provenance analysis suggests that the study sediments have two provenance end-members; local volcanic sources are dominant, and eolian dust from the Asian continent has a smaller contribution. During glacial periods, eolian input to the western Philippine Sea was enhanced. In contrast, material supply from local volcanics in- creased during interglacial periods. Changes in eolian input to the study area were probably related to the strength of the East Asian winter monsoon （EAWM） as well as aridity in the Asian continent on an orbital time scale, and were partly influenced by local control factors on shorter time scales. Therefore, we propose that the present study expands the application of the REE-based method for quantitatively estimating the eolian component from the mid-latitude northern Pacific to the low-latitude western Pacific. Additionally, the study preliminarily confirms the influence of EAWM-transported eolian materi- al on sedimentation in the western Philippine Sea since 700 ka.展开更多
文摘[Objective] To provide a theoretical basis for high-yield breeding of broom sorghum.[Method] Using 11 kinds of broom sorghum collected at home as research objects, the differences in morphological characteristics of broom sorghum were compared through the survey of some indicators, such as plant height, tillering, inflorescence, stem node, stem-leaf ratio, yield, and so on. [Result] The 11 kinds of broom sorghum were different in morphological characteristics with large amplitude of plant height; zygl-1, zygl-6, zygl-8 and zygl-9 were appropriate for fixed broom type; zygl-9 had the highest integrated production. [Condusion] The study laid the foundation for further exploring breeding, cultivation and promotion of broom sorghum.
基金Supported by the National Natural Science Foundation of China(Nos.41430965,41376057)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA11030302)
文摘The Okinawa Trough is a natural laboratory for the study of air-sea interaction and paleoenvironmental change. It has been demonstrated that present offshore export of particles in the bottom nepheloid layer occur primarily with downwelling from the northeast winter monsoon, which is inhibited by a transverse circulation pattern in summer. This current system was very different during the Last Glacial Maximum owing to low sea level （-120 m） and exposure of a large shelf area. We collected sediment core Oki01 from the middle Okinawa Trough during 2012 using R/V Kexue No. 1 to elucidate the timing and cause of the current system transition in the East China Sea. Clay mineral, dry density, and elemental （Ti, Ca） composition of core Oki01 was analyzed. The results indicate that clay minerals derived mainly from the Huanghe （Yellow） and the Changjiang （Yangtze） Rivers during 16.0-11.6 ka, and the modem current system in the East China Sea formed beginning in the early Holocene. Therefore, mixing of East China Sea continental shelf, Changjiang River and partially Taiwan Island sediment are the major contributors. The decrease of log（Ti/Ca） and alternating provenance since the early Holocene indicate less sediment from the East China in summer because of resistance of the modern current system, i.e., a ＂water barrier＂ and upwelling. Conversely, sediment delivery persists in winter and log（Ti/Ca） indicates the winter monsoon signal since the early Holocene. Our evidence also suggests that sediment from Taiwan Island could be transported by the Kuroshio Current to the middle Okinawa Trough, where it mingles with winter monsoon- induced export of sediment from the Changjiang River and East China Sea continental shelf. Although the present research advances understanding of the evolutionary history of paleoenvironmental change in the Okinawa Trough, more sediment cores should be retrieved over wide areas to construct a larger scenario.
基金This research was supported by the National Key R＆D Program of China （2017YFA0603802）, the National Natural Science Foundation of China （41661144005 and 41320104007）, and the CAS-PKU Joint Research Program. We would like to thanks the IPCC for providing the CMIP5 datasets （http：//www.ipccdata.org/sim/gcm_monthly/AR5/Reference-Archive.html）.
文摘In this study, the East Asian summer climate changes under the 1.5 ℃ global warming （1.5 GW） target in 30 simulations derived from 15 coupled models within the Coupled Model Intercomparison Program phase 5 （CMIP5） are examined. Compared with the current summer climate （1975-2005）, both surface air temperature and precipitation increase significantly over the East Asian continent during the 1.5 GW period （average period 2021-2051）. In northeastern China this is particularly pronounced with regional averaged precipitation increases of more than 7.2%, which is greater than that for the whole East Asian continent （approximately 4.2%）. Due to stronger enhancement of precipitation north of 40°N, the leading empirical orthogonal function （EOF） mode of summer precipitation over the East Asian continent changes from tripolar-like mode to dipole mode. As there is stronger surface warming over the East Asian continent than that over surrounding ocean, the land-sea thermal contrast is enhanced during the 1.5 GW period. As a result, the monsoon circulation in the lower troposphere is significantly strengthened, which causes the increased summer precipitation over the East Asian continent. In addition, larger interannual variabilities of East Asian summer monsoon circulation and associated precipitation are also suggested for the 1.5 GW period.
基金Natural Science Foundation of China(40765002)Public Interest Research Special Foundation(meteorology)of China(200906002)
文摘According to the national standard(2006)on tropical cyclone(TC)intensity,TCs are categorized into six intensity types,namely,tropical depression(TD),tropical storm(TS),severe tropical storm(STS), typhoon(TY),severe typhoon(STY),and super severe typhoon(SSTY).Fifty-eight years(1949–2006)of the datasets from the Yearbook of Typhoons and Yearbook of Tropical Cyclones were used to study the variation characteristics of TCs making landfalls in China's Mainland,Hainan and Taiwan islands.The main results are as follows.First,interannual or interdecadal variations in the number of landfalling TCs at different intensities exist.As far as long-term trends are concerned,the TD and TS frequencies show a significant linearly decreasing trend while those of STY show a significant linearly increasing trend.Second, a significant period of 6–8 years exist in the variations of annual landfalling TD,TS,and STS frequencies while quasi-16-year periods are found in the annual TY frequency.Third,TD and TS are generated mostly over the South China Sea,while TY,STY,and SSTY mostly over the waters southeast of the Bashi Channel and the ocean to the east of the Philippines.Fourth,as far as interdecadal trends are concerned,the frequencies of landfalling TD and TS generated over the South China Sea show significant linearly decreasing trends.However,TY and STY show significant linearly increasing trends.
基金National Science Foundation of China under contract (4067505440505019)China Meteorological Administration (CMATG2006L03)
文摘The relationship between the intensity of the South China Sea summer monsoon （SCSSM） and the Nino3.4 index and anomalous atmospheric circulation patterns associated with a strong and weak SCSSM are investigated using the NCEP/NCAR reanalysis data, Extended Reconstructed Sea Surface Temperature （ERSST） data and Climate Prediction Center Merged Analysis of Precipitation （CMAP） data. The SCSSM is significantly positively correlated with the Nino3.4 index in the succeeding northern autumn and winter. In the strong minus weak SCSSM composite, a positive East Asia-Pacific teleconnection （EAP） pattern and a negative Europe-Asian-Pacific teleconnection （EUP） pattern appear in the 500 hPa height difference field; low-level cross-equatorial flows are strengthened over the Maritime Continent （MC） region; positive （negative） precipitation anomalies occur in the South China Sea and western north Pacific （MC）. A possible mechanism through which SCSSM affects ENSO is proposed. A strong （weak） SCSSM strengthens （weakens） cross-equatorial flows over the MC. The anomalous cross-equatorial flows cool （warm） the SST around the MC through enhanced （reduced） surface latent heat fluxes. The cooling （warming） further leads to suppressed （enhanced） convection over the MC, and causes the anomalous westerly （easterly） in the equatorial western Pacific, which favors the onset of E1 Nino （La Nina） through modulating the positive air-sea feedback process.
基金Supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (No.KZCX1-YW-12)the National Natural Science Foundation of China (No.40706011)the Open Foundation of Key Laboratory of Marine Science and Numerical Modeling (MASNUM)
文摘We compared nonlinear principal component analysis(NLPCA) with linear principal component analysis(LPCA) with the data of sea surface wind anomalies(SWA),surface height anomalies(SSHA),and sea surface temperature anomalies(SSTA),taken in the South China Sea(SCS) between 1993 and 2003.The SCS monthly data for SWA,SSHA and SSTA(i.e.,the anomalies with climatological seasonal cycle removed) were pre-filtered by LPCA,with only three leading modes retained.The first three modes of SWA,SSHA,and SSTA of LPCA explained 86%,71%,and 94% of the total variance in the original data,respectively.Thus,the three associated time coefficient functions(TCFs) were used as the input data for NLPCA network.The NLPCA was made based on feed-forward neural network models.Compared with classical linear PCA,the first NLPCA mode could explain more variance than linear PCA for the above data.The nonlinearity of SWA and SSHA were stronger in most areas of the SCS.The first mode of the NLPCA on the SWA and SSHA accounted for 67.26% of the variance versus 54.7%,and 60.24% versus 50.43%,respectively for the first LPCA mode.Conversely,the nonlinear SSTA,localized in the northern SCS and southern continental shelf region,resulted in little improvement in the explanation of the variance for the first NLPCA.
基金jointly supported by the Second Tibetan Plateau Scientific Expedition Program (2019QZKK0104)China and the National Natural Science Foundation of China (41630425, 41761144074)
文摘Lightning is an important natural source of wildfires and oxynitride,and hence significantly influences ecological systems and atmospheric chemistry.Here,we choose South Asia,an important region for global water reallocation and global climate changes,to examine lightning variations based on the longest existing lightning dataset from the OTD/LIS observations.We identify a clear increase in lightning density in the research region,increasing at a rate of 0.096 fl km^(-2)a^(-1)over the last two decades.Multiple linear regression analysis is adopted to identify the main influencing factors among ten potential thermodynamic or microphysical factors and the crucial areas contributing to the increases in lightning.The surface latent heat flux along the west coast of the Indian subcontinent is the largest contributor,explaining52%of the lightning variance and contributing to a 0.025 fl km^(-2)a^(-1)increase.The sea surface temperature in the Arabian Sea,the convective available potential energy(CAPE)over the northwestern Indian subcontinent,and the wind shear along the northwestern coast also make important contributions to the lightning increase,indicating that the thermodynamic effects overwhelm the microphysical effects on lightning activity over the South Asia region.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41176011, U1133001, U0933001)Guangdong University Pearl River Scholar Bonus Schemes (Grant No. GDUPS-2010)
文摘Near-inertial motion is an important dynamic process in the upper ocean and plays a significant role in mass, heat, and energy transport across the thermocline. In this study, the dissipation of wind-induced near-inertial energy in the thermocline is investigated by using observation data collected in July and August 2005 during the tropical storm Washi by a moored system at(19°35′N, 112°E) in the continental shelf region off Hainan Island. In the observation period, the near-inertial part dominated the observed ocean kinetic energy and about 80% of the near-inertial energy dissipated in the upper layer. Extremely strong turbulent mixing induced by near-inertial wave was observed in the thermocline, where the turbulent energy dissipation rate increased by two orders of magnitude above the background level. It is found that the energy loss of near-inertial waves in the thermocline is mainly in the large-scales. This is different from the previous hypothesis based on "Kolmogorov cascade" turbulence theory that the kinetic energy is dissipated mainly by small-scale motions.
基金supported by the Public Science and Technology Research Funds Projects of the OceanState Oceanic Administration of the People’s Republic of China(Grant No.201005003)+1 种基金the National Natural Science Foundation of China(Grant Nos.41376064,41230959,41106043,and 41076033)the National Basic Research Program of China(Grant No.2007CB815903)
文摘Based on a δ180 chronology, rare earth elements （REE） and other typical elements in sediments from core MD06-3047 in the western Philippine Sea were analyzed to constrain the provenances of the sediments and investigate quantitative changes in the Asian eolian input to the study area over the last 700 ka. Among the competing processes that might affect REE compositions, sediment provenance is the most important one. Provenance analysis suggests that the study sediments have two provenance end-members; local volcanic sources are dominant, and eolian dust from the Asian continent has a smaller contribution. During glacial periods, eolian input to the western Philippine Sea was enhanced. In contrast, material supply from local volcanics in- creased during interglacial periods. Changes in eolian input to the study area were probably related to the strength of the East Asian winter monsoon （EAWM） as well as aridity in the Asian continent on an orbital time scale, and were partly influenced by local control factors on shorter time scales. Therefore, we propose that the present study expands the application of the REE-based method for quantitatively estimating the eolian component from the mid-latitude northern Pacific to the low-latitude western Pacific. Additionally, the study preliminarily confirms the influence of EAWM-transported eolian materi- al on sedimentation in the western Philippine Sea since 700 ka.
