The interdecadal variability of the East Asia summer monsoon during 1951～1999 is analyzed by using two different East Asia monsoon indices. The results agree on the point that the East Asia monsoon has undergone an i...The interdecadal variability of the East Asia summer monsoon during 1951～1999 is analyzed by using two different East Asia monsoon indices. The results agree on the point that the East Asia monsoon has undergone an interdecadal variability in the mid-1970s. The intensity of the East Asia monsoon is weaker after this transition. Moreover the intensity and location of subtropical high that is an important component in East Asia monsoon system also shows interdecadal variation obviously. It is the interdecadal variation in atmospheric circulation that causes the drought over North China and flooding along the middle and lower reaches of the Yangtze River after the mid-1970s.展开更多
There are two different opinions on the formation history of Huanghe (Yellow) River. One postulates that Huanghe River might have come into existence before Tertiary. The other supposes that it joined up into a long r...There are two different opinions on the formation history of Huanghe (Yellow) River. One postulates that Huanghe River might have come into existence before Tertiary. The other supposes that it joined up into a long river only in the last stage of Late Pleistocene. The appearance of Huanghe River is believed to have close relation to the uplifting of Tibetan Plateau. It is not likely that it could have come into being before its high elevation riverhead was formed. Today Huanghe River occurred probably during the recession of the sea in glacial periods. In the last glacial age, the climate was very harsh in the area north of the modern estuary of Changjiang (Yangtse) River; some areas were permafrost and the others barren deserts. At that time, eolation was the major exogenic force on exposed shelf. Beginning from 12 Ka BP, the global climate warmed up, resulting in gradual disappearance of continental mountain glaciers retreated, and sea level rose. Consequently, Huanghe River was replenished with water to become modern river system. With continued rising of sea level, Huanghe River delta moved continuously eastward.展开更多
The activity of South China Sea southwest monsoon (SCSSM) has direct impacts on the anomalies of important weather in Guangdong province during the raining seasons. So it is necessary to explore thoroughly the activit...The activity of South China Sea southwest monsoon (SCSSM) has direct impacts on the anomalies of important weather in Guangdong province during the raining seasons. So it is necessary to explore thoroughly the activity pattern of SCSSM and its relationship with important weather anomalies in the province. In this paper, the methods of composite analysis and correlation statistics are used to study the relationship between the onset date and intensity of SCSSM and the important weather, such as precipitation trends in Guangdong province during the annually first and second raining seasons, the timing of the annually first and last typhoon and the number of typhoons landing in Guangdong province. The results show that the rainfall is less than normal during the first raining season, but more than normal during the second one and there are more tropical cyclones landing in Guangdong province in the years of early SCSSM onset. The rainfall is more than normal during the second raining season and there are more tropical cyclones landing in Guangdong province in the years of strong SCSSM. The relationship between the SST of April - June, July - September and previous winter (December - February) and 500 hPa geopotential height and the onset date and intensity of SCSSM is analyzed. Some mechanisms between the onset dates and intensity of SCSSM and the important weather anomalies in Guangdong province are preliminarily explored. The results can be used for reference in short-term climate forecast.展开更多
Detailed analysis and comparisons are made on the data of Hong Kong wind-profiler and the weather/precipitation every hour during the HUAMEX and the experiment for the monsoon of the South China Sea (SCSMEX) in 1998. ...Detailed analysis and comparisons are made on the data of Hong Kong wind-profiler and the weather/precipitation every hour during the HUAMEX and the experiment for the monsoon of the South China Sea (SCSMEX) in 1998. It is found that the wind-profiler data could reveal the meso-scale phenomena in the PBL of Southwest Monsoon, which was closely related to rainstorms. The center of the low-level jet under the altitude of 2 km, which corresponded to the appearance of heavy rain, appeared 1 to 2 hours after the center of low-level jet (LLJ) did above the 2-km altitude. An index I is designed to represent the intensity and height of the LLJ. This index can express clearly the close relationship between the precipitation and the LLJ. The results show that the wind-profiler is somewhat predictive to a rainstorm.展开更多
基金Natural Science Foundation of China (40365001) Intramural research program of Yunnan University (2002Q014ZH)
文摘The interdecadal variability of the East Asia summer monsoon during 1951～1999 is analyzed by using two different East Asia monsoon indices. The results agree on the point that the East Asia monsoon has undergone an interdecadal variability in the mid-1970s. The intensity of the East Asia monsoon is weaker after this transition. Moreover the intensity and location of subtropical high that is an important component in East Asia monsoon system also shows interdecadal variation obviously. It is the interdecadal variation in atmospheric circulation that causes the drought over North China and flooding along the middle and lower reaches of the Yangtze River after the mid-1970s.
基金Project 40076014 supported by NSFC &"Study on ocean geology environment and ocean torrent" supported by Natural Science Fund of Qingdao.
文摘There are two different opinions on the formation history of Huanghe (Yellow) River. One postulates that Huanghe River might have come into existence before Tertiary. The other supposes that it joined up into a long river only in the last stage of Late Pleistocene. The appearance of Huanghe River is believed to have close relation to the uplifting of Tibetan Plateau. It is not likely that it could have come into being before its high elevation riverhead was formed. Today Huanghe River occurred probably during the recession of the sea in glacial periods. In the last glacial age, the climate was very harsh in the area north of the modern estuary of Changjiang (Yangtse) River; some areas were permafrost and the others barren deserts. At that time, eolation was the major exogenic force on exposed shelf. Beginning from 12 Ka BP, the global climate warmed up, resulting in gradual disappearance of continental mountain glaciers retreated, and sea level rose. Consequently, Huanghe River was replenished with water to become modern river system. With continued rising of sea level, Huanghe River delta moved continuously eastward.
基金Research fund for tropical marine meteorology (200423, 200512)Natural Science Foundation of China (40675054)Open research project of China Meteorological Administration (CMATG2006L03)
文摘The activity of South China Sea southwest monsoon (SCSSM) has direct impacts on the anomalies of important weather in Guangdong province during the raining seasons. So it is necessary to explore thoroughly the activity pattern of SCSSM and its relationship with important weather anomalies in the province. In this paper, the methods of composite analysis and correlation statistics are used to study the relationship between the onset date and intensity of SCSSM and the important weather, such as precipitation trends in Guangdong province during the annually first and second raining seasons, the timing of the annually first and last typhoon and the number of typhoons landing in Guangdong province. The results show that the rainfall is less than normal during the first raining season, but more than normal during the second one and there are more tropical cyclones landing in Guangdong province in the years of early SCSSM onset. The rainfall is more than normal during the second raining season and there are more tropical cyclones landing in Guangdong province in the years of strong SCSSM. The relationship between the SST of April - June, July - September and previous winter (December - February) and 500 hPa geopotential height and the onset date and intensity of SCSSM is analyzed. Some mechanisms between the onset dates and intensity of SCSSM and the important weather anomalies in Guangdong province are preliminarily explored. The results can be used for reference in short-term climate forecast.
基金A key project in Natural Science Foundation of China (980456032) Project 973 (G1998040907) Foundation Project for Visiting Scholar in Key Laboratory of Higher Education College
文摘Detailed analysis and comparisons are made on the data of Hong Kong wind-profiler and the weather/precipitation every hour during the HUAMEX and the experiment for the monsoon of the South China Sea (SCSMEX) in 1998. It is found that the wind-profiler data could reveal the meso-scale phenomena in the PBL of Southwest Monsoon, which was closely related to rainstorms. The center of the low-level jet under the altitude of 2 km, which corresponded to the appearance of heavy rain, appeared 1 to 2 hours after the center of low-level jet (LLJ) did above the 2-km altitude. An index I is designed to represent the intensity and height of the LLJ. This index can express clearly the close relationship between the precipitation and the LLJ. The results show that the wind-profiler is somewhat predictive to a rainstorm.
