Based on the reanalysis data of monthly mean global SST and wind from the NCEP/NCAR and the observation data of rain seasons in 124 stations of Yunnan province from 1961 to 2006, we applied the analytical methods of c...Based on the reanalysis data of monthly mean global SST and wind from the NCEP/NCAR and the observation data of rain seasons in 124 stations of Yunnan province from 1961 to 2006, we applied the analytical methods of correlation analysis and composite analysis and a significance testing method to two sets of samples of average differences. The goal is to investigate into the influence of the Southern Hemispheric(SH) SST on the summer precipitation in Yunnan from January to May so as to identify the key time and marine regions. Physical mechanisms are obtained by analyzing the influence of sea level wind and the key marine regions on the precipitation during Yunnan's rain season.Results show that there is indeed significant relationship between the SST in SH and summer precipitation in Yunnan.The key areas for influencing the summer precipitation are mainly distributed in a region called "West Wind Drift" in the SH, including the Southeast Indian, southern Australia, west coast of eastern Pacific off Chile, Peru and the southwest Atlantic Magellan. Besides, the most significant marine region is the west coast of Chile and Peru(cold-current areas of the eastern Pacific). Diagnostic analysis results also showed that monsoons in the Bay of Bengal, a cross-equatorial flow in the Indian Ocean near the equator and southwest monsoon in India weaken during the warm phase of the Peruvian cold current in the eastern Pacific. Otherwise, they strengthen.展开更多
By using regular meteorological data, physical quantity fields, satellite pictures and Doppler radar echo data, we analyze the mesoscale features and the conditions of 4 successive heavy precipitation processes in Yun...By using regular meteorological data, physical quantity fields, satellite pictures and Doppler radar echo data, we analyze the mesoscale features and the conditions of 4 successive heavy precipitation processes in Yunnan aroused by the storm over the Bay in the early summer. The results show that the life of the storm over the Bay is usual 2 or 3 days and the cloud top temperature of the storm is always below -65℃. The storm over the Bay affects Yunnan by mesoscale convective cloud clusters, cloud system in peripheral or weaken itse,fmoving to the northeast. The Tibetan Plateau shear lines and vortexes, NE-SW convergence channels and southwest wind convergence supply favorable circulation background and dynamical conditions. There are many common features about Doppler radar echoes, the flocculent echoes with intensity about 35-45 dBZ move to the east to produce successive precipitation in Yunnan, and the mesoscale features of southwest jet and wind veering with altitude not only are favorable to transport warm and moist airflow brought to the north by the storm over the Bay. but also are favorable to convective development.展开更多
Based on the monthly precipitation data of 126 observation stations from 1961 to 2000 in Yunnan Province, the interannual and decadal variability of precipitation in rainy seasons are studied by using wavelet analysis...Based on the monthly precipitation data of 126 observation stations from 1961 to 2000 in Yunnan Province, the interannual and decadal variability of precipitation in rainy seasons are studied by using wavelet analysis. It is shown that there is a 2-6 year oscillation at the interannual time scales and a quasi-30 year oscillation at the decadal time scales. These periodic oscillations relate to the distribution of tropical heat content. When the precipitation is much more (less) than normal, the upper seawater is colder (warmer) in almost all the tropical Indian Ocean, and warmer (colder) in the western Pacific as well as colder (warmer) in the eastern Pacific. The key areas of the anomaly heat content distribution that have significant correlation to the Yunnan precipitation in rainy season are in the southern hemispheric Indian Ocean with a dipole pattern in the winter as well as in the deep basin of the South China Sea (SCS) before the Yunnan rainy season begins. Therefore, the anomalous distributions of the heat content in the southern Indian Ocean and the SCS In winter are good indicators for predicting drought or flood in Yunnan Province in the following rainy season.展开更多
Sea surface temperature anomaly (SSTA) exerts great influence on the generation of global weather and climate. Much progress has been made with respect to SSTA in the Pacific Ocean region in contrast to the Indian Oce...Sea surface temperature anomaly (SSTA) exerts great influence on the generation of global weather and climate. Much progress has been made with respect to SSTA in the Pacific Ocean region in contrast to the Indian Ocean. The IAP9L model, which is developed at the Institute of Atmospheric Physics of the Chinese Academy of Science, is used to simulate the influence of the Indian Ocean SSTA on the general circulation and weather/climate anomalies in the monsoon region of Asia. It is found that the warm (cool) SSTA in the equatorial low latitudes of the Indian Ocean triggers winter (summer) teleconnection patterns in middle and higher latitudes of the Northern Hemisphere that are similar to PNA or EAP. They play a very important role in the anomaly of circulation or weather and climate in the middle and lower latitudes of the Asian summer monsoon region. With the warm (cool) SSTA forcing in the Indian Ocean, the Asian summer monsoon sets up at a late (early) date and withdraws at a early (late) date, lasting for a short (long) duration at a weak (strong) intensity. The Indian Ocean SSTA is shown to be an indicator for precipitation variation in China.展开更多
Based on the lightning data acquired by a lightning imaging sensor(LIS)carried on the TRMM satellite from 1998 to 2013,the spatial distribution,seasonal,monthly,and diurnal characteristics of lightning activity in the...Based on the lightning data acquired by a lightning imaging sensor(LIS)carried on the TRMM satellite from 1998 to 2013,the spatial distribution,seasonal,monthly,and diurnal characteristics of lightning activity in the Pan-Pearl River Delta were analyzed.The results show that in the Pan-Pearl River Delta,lightning activity was more in the south and less in the north.Near 23°N,lightning density was high from Guangdong and Guangxi to the southern edge of Yunnan.Lightning density weakened continuously as the latitude increased.Among the provinces in the Pan-Pearl River Delta,the maximum and average of lightning density in Hainan Province was greater than that of other provinces.Besides,the lightning activity showed obvious seasonal changes.In the whole year,lightning activity was the weakest in November and next February.Lightning activity in most areas of the Pan-Pearl River Delta was the strongest in August.The peak of lightning activity in most areas of the Pan-Pearl River Delta occurred from 12:00 to 20:00.Lightning activity was the weakest between 07:00 and 10:00 in most areas.展开更多
To surmount the deficiency in studying the multiple equilibrium states in the atmosphere motion with highly truncated spectral method, the trigonometric functions for describing the proto-typical 500 hPa height fields...To surmount the deficiency in studying the multiple equilibrium states in the atmosphere motion with highly truncated spectral method, the trigonometric functions for describing the proto-typical 500 hPa height fields and the outgoing long wave radiation (OLR) fields are retrieved re-spectively for the northward bias and the southward bias years of the western Pacific subtropical high with corresponding observational data and the optimum subset retrieval method for four fac-tors. Then the evolution mechanism of the western Pacific subtropical high is studied by means of multiple equilibrium state theory. The results show that the cause of inducing the abnormal location of the western Pacific subtropical high is differences in the early external thermal forcing, which evoke different waveforms in atmosphere. If the early meridional and zonal external thermal forcing differences are stronger, there are wave-mean flow and wave-wave interactions between the response waveforms in atmosphere. In such a case, the western Pacific subtropical high shifts northward obviously. On the contrary, when the early meridional and zonal external thermal forcing differences are weaker, there is no wave-mean flow interaction between the response waveforms in atmosphere, and accordingly the position of the western Pacific subtropical high oscillates with the external thermal forcing oscillation, and is on the south of normal.展开更多
Statistical tests and error analysis of cloud drift winds（CDWs） from the FY-2C satellite were made by using radiosonde observations.According to the error characteristics of the CDW,a bias correction using the therm...Statistical tests and error analysis of cloud drift winds（CDWs） from the FY-2C satellite were made by using radiosonde observations.According to the error characteristics of the CDW,a bias correction using the thermal wind theory was applied in the data quality control.The CDW data were then assimilated into the GRAPES-meso model via the GRAPES-3DVar.A torrential rain event that occurred in northwestern China during 1-2 July 2005 was simulated.The results indicate that the CDW data were mainly distributed above 500 hPa and the largest amount of data were at 250 hPa.The CDW data below 500 hPa had errors in both the wind direction and wind speed,and the distribution of the errors was irregular,so these data were discarded.The CDW data above 500 hPa had smaller errors,which presented a Gaussian distribution,so these data were adopted.With the assimilation of the CDW data,the southwest airflow near the torrential rain area became stronger in the initial wind field,which intensified the moisture transport and water vapor flux convergence,and finally improved the accuracy of the 24-h forecast of the torrential rain in both rain intensity and rain areal coverage.展开更多
基金National Natural Science Foundation of China(41075072,41065004)National Natural Science Foundation of China-Yunnan Province Joint Foundation(U0833602)+2 种基金Specialized Project for Forecasters in Yunnan Province(YB201202)Project for Fourth Program of Undergraduates in Yunnan Province(ynuy201154)Integration and Demonstration of Techniques for Mitigating and Controlling Eruptive Disasters in Southwest China,a project of National Science and Technology Support for the 12th Five-Year Economic Development(2012BAD20B06)
文摘Based on the reanalysis data of monthly mean global SST and wind from the NCEP/NCAR and the observation data of rain seasons in 124 stations of Yunnan province from 1961 to 2006, we applied the analytical methods of correlation analysis and composite analysis and a significance testing method to two sets of samples of average differences. The goal is to investigate into the influence of the Southern Hemispheric(SH) SST on the summer precipitation in Yunnan from January to May so as to identify the key time and marine regions. Physical mechanisms are obtained by analyzing the influence of sea level wind and the key marine regions on the precipitation during Yunnan's rain season.Results show that there is indeed significant relationship between the SST in SH and summer precipitation in Yunnan.The key areas for influencing the summer precipitation are mainly distributed in a region called "West Wind Drift" in the SH, including the Southeast Indian, southern Australia, west coast of eastern Pacific off Chile, Peru and the southwest Atlantic Magellan. Besides, the most significant marine region is the west coast of Chile and Peru(cold-current areas of the eastern Pacific). Diagnostic analysis results also showed that monsoons in the Bay of Bengal, a cross-equatorial flow in the Indian Ocean near the equator and southwest monsoon in India weaken during the warm phase of the Peruvian cold current in the eastern Pacific. Otherwise, they strengthen.
基金Project of China Meteorological Administrator (2006): "Operation System R&D of YunnanLightning Observation and Forecast"
文摘By using regular meteorological data, physical quantity fields, satellite pictures and Doppler radar echo data, we analyze the mesoscale features and the conditions of 4 successive heavy precipitation processes in Yunnan aroused by the storm over the Bay in the early summer. The results show that the life of the storm over the Bay is usual 2 or 3 days and the cloud top temperature of the storm is always below -65℃. The storm over the Bay affects Yunnan by mesoscale convective cloud clusters, cloud system in peripheral or weaken itse,fmoving to the northeast. The Tibetan Plateau shear lines and vortexes, NE-SW convergence channels and southwest wind convergence supply favorable circulation background and dynamical conditions. There are many common features about Doppler radar echoes, the flocculent echoes with intensity about 35-45 dBZ move to the east to produce successive precipitation in Yunnan, and the mesoscale features of southwest jet and wind veering with altitude not only are favorable to transport warm and moist airflow brought to the north by the storm over the Bay. but also are favorable to convective development.
文摘Based on the monthly precipitation data of 126 observation stations from 1961 to 2000 in Yunnan Province, the interannual and decadal variability of precipitation in rainy seasons are studied by using wavelet analysis. It is shown that there is a 2-6 year oscillation at the interannual time scales and a quasi-30 year oscillation at the decadal time scales. These periodic oscillations relate to the distribution of tropical heat content. When the precipitation is much more (less) than normal, the upper seawater is colder (warmer) in almost all the tropical Indian Ocean, and warmer (colder) in the western Pacific as well as colder (warmer) in the eastern Pacific. The key areas of the anomaly heat content distribution that have significant correlation to the Yunnan precipitation in rainy season are in the southern hemispheric Indian Ocean with a dipole pattern in the winter as well as in the deep basin of the South China Sea (SCS) before the Yunnan rainy season begins. Therefore, the anomalous distributions of the heat content in the southern Indian Ocean and the SCS In winter are good indicators for predicting drought or flood in Yunnan Province in the following rainy season.
基金Applied Foundation of Science and Technology Committee of Yunnan Province(97D033Q)and LASG
文摘Sea surface temperature anomaly (SSTA) exerts great influence on the generation of global weather and climate. Much progress has been made with respect to SSTA in the Pacific Ocean region in contrast to the Indian Ocean. The IAP9L model, which is developed at the Institute of Atmospheric Physics of the Chinese Academy of Science, is used to simulate the influence of the Indian Ocean SSTA on the general circulation and weather/climate anomalies in the monsoon region of Asia. It is found that the warm (cool) SSTA in the equatorial low latitudes of the Indian Ocean triggers winter (summer) teleconnection patterns in middle and higher latitudes of the Northern Hemisphere that are similar to PNA or EAP. They play a very important role in the anomaly of circulation or weather and climate in the middle and lower latitudes of the Asian summer monsoon region. With the warm (cool) SSTA forcing in the Indian Ocean, the Asian summer monsoon sets up at a late (early) date and withdraws at a early (late) date, lasting for a short (long) duration at a weak (strong) intensity. The Indian Ocean SSTA is shown to be an indicator for precipitation variation in China.
基金Supported by the National Natural Science Foundation of China(42065006)the Second Tibetan Plateau Scientific Expedition and Research(STEP)Program(2019QZKK0105)the Science and Technology Program of Yunnan"Impact Assessments and Monitor-forecasting Technology of Meteorological Disasters for Yunnan Plateau Characteristic Agriculture under Climate Change"(2018BC007).
文摘Based on the lightning data acquired by a lightning imaging sensor(LIS)carried on the TRMM satellite from 1998 to 2013,the spatial distribution,seasonal,monthly,and diurnal characteristics of lightning activity in the Pan-Pearl River Delta were analyzed.The results show that in the Pan-Pearl River Delta,lightning activity was more in the south and less in the north.Near 23°N,lightning density was high from Guangdong and Guangxi to the southern edge of Yunnan.Lightning density weakened continuously as the latitude increased.Among the provinces in the Pan-Pearl River Delta,the maximum and average of lightning density in Hainan Province was greater than that of other provinces.Besides,the lightning activity showed obvious seasonal changes.In the whole year,lightning activity was the weakest in November and next February.Lightning activity in most areas of the Pan-Pearl River Delta was the strongest in August.The peak of lightning activity in most areas of the Pan-Pearl River Delta occurred from 12:00 to 20:00.Lightning activity was the weakest between 07:00 and 10:00 in most areas.
基金This work was supported by the National Key Program for Developing Basic Research (Grant No. 1998040900) and the National Natural Science Foundation of China (Grant No. D49965001).
文摘To surmount the deficiency in studying the multiple equilibrium states in the atmosphere motion with highly truncated spectral method, the trigonometric functions for describing the proto-typical 500 hPa height fields and the outgoing long wave radiation (OLR) fields are retrieved re-spectively for the northward bias and the southward bias years of the western Pacific subtropical high with corresponding observational data and the optimum subset retrieval method for four fac-tors. Then the evolution mechanism of the western Pacific subtropical high is studied by means of multiple equilibrium state theory. The results show that the cause of inducing the abnormal location of the western Pacific subtropical high is differences in the early external thermal forcing, which evoke different waveforms in atmosphere. If the early meridional and zonal external thermal forcing differences are stronger, there are wave-mean flow and wave-wave interactions between the response waveforms in atmosphere. In such a case, the western Pacific subtropical high shifts northward obviously. On the contrary, when the early meridional and zonal external thermal forcing differences are weaker, there is no wave-mean flow interaction between the response waveforms in atmosphere, and accordingly the position of the western Pacific subtropical high oscillates with the external thermal forcing oscillation, and is on the south of normal.
基金Supported by the Natural Science Foundation of Yunnan Province(U0933603)the Yunnan Province Science and Technology Program(2009CA023)the Yunnan Province Key Science and Technology and High-tech Project(2006SG25)
文摘Statistical tests and error analysis of cloud drift winds（CDWs） from the FY-2C satellite were made by using radiosonde observations.According to the error characteristics of the CDW,a bias correction using the thermal wind theory was applied in the data quality control.The CDW data were then assimilated into the GRAPES-meso model via the GRAPES-3DVar.A torrential rain event that occurred in northwestern China during 1-2 July 2005 was simulated.The results indicate that the CDW data were mainly distributed above 500 hPa and the largest amount of data were at 250 hPa.The CDW data below 500 hPa had errors in both the wind direction and wind speed,and the distribution of the errors was irregular,so these data were discarded.The CDW data above 500 hPa had smaller errors,which presented a Gaussian distribution,so these data were adopted.With the assimilation of the CDW data,the southwest airflow near the torrential rain area became stronger in the initial wind field,which intensified the moisture transport and water vapor flux convergence,and finally improved the accuracy of the 24-h forecast of the torrential rain in both rain intensity and rain areal coverage.
