By using China National Climate Center’s 74 circulation characteristics, DERF2.0, BCC-CSM models and Wenzhou Typhoon Network data, and using linear regression, correlation coefficients and other research methods, the...By using China National Climate Center’s 74 circulation characteristics, DERF2.0, BCC-CSM models and Wenzhou Typhoon Network data, and using linear regression, correlation coefficients and other research methods, the variations about typhoon frequency in July from 1951 to 2020 and the large-scale circulation system in July 2020 are analyzed. The results show that 1) in the recent 70 years, the frequency of typhoon generation has slowly decreased, while the frequency of landing typhoons in China has slowly increased;2) typhoon frequency has varying degrees of negative correlation with the intensity of subtropical high in different regions of the northern hemisphere, especially with the area index and intensity index of the South China Sea subtropical high;3) in July 2020, the area and intensity of the subtropical high in the Northwest Pacific were abnormally large and strong. Easterly winds prevailed in the tropics, and the cross-equatorial airflow was weak, resulting in a severe reduction in the frequency of typhoon generation, leading to “no-typhoon” events.展开更多
Tropical Cyclone (TC) activity is an important feature of China's climate that can have important impacts on precipitation and can cause extensive property damage. In particular, precipitation from TCs contributes...Tropical Cyclone (TC) activity is an important feature of China's climate that can have important impacts on precipitation and can cause extensive property damage. In particular, precipitation from TCs contributes a significant portion of overall precipitation. This study deals with typhoons that influence China and focuses on their impact on China's precipitation. Four aspects are examined in this research. Firstly, the study of influencing typhoon frequency reveals that the main season that typhoons affect China is from May to November, especially between July and September. The frequency of influencing typhoons was steady during the past 40 years. Secondly, inspection of the climatology of station typhoon precipitation shows that Hainan and the southeastern coastalmost regions are most frequently affected by typhoons, and most of the regions south of the Yangtze River are affected by typhoons each year. Meanwhile, during 1957-1996, most of the typhoon-influenced regions show decreasing trends in typhoon precipitation but only the trends in southern Northeast China are significant. Thirdly, examination of the typhoon cases shows that there exists it significant linear relationship between the precipitation volume and impacted area. Finally, study of variations of typhoon impacts on China's precipitation suggests that there exists a decreasing trend in the contribution of typhoon precipitation to overall precipitation, while total annual volume of typhoon precipitation decreases significantly during the period.展开更多
Typhoons with erratic movement are studied for their annual frequency of occurrence over the South China Sea and Northwest Pacific,based on 102 years of data (1884—1985).It discovers that the years with higher fre- q...Typhoons with erratic movement are studied for their annual frequency of occurrence over the South China Sea and Northwest Pacific,based on 102 years of data (1884—1985).It discovers that the years with higher fre- quency tend to get together.There are well-defined periods of 12 and 30 years,revealed with the maximum entropy method (MEM),the latter of low-frequency oscillation being clearer.展开更多
文摘By using China National Climate Center’s 74 circulation characteristics, DERF2.0, BCC-CSM models and Wenzhou Typhoon Network data, and using linear regression, correlation coefficients and other research methods, the variations about typhoon frequency in July from 1951 to 2020 and the large-scale circulation system in July 2020 are analyzed. The results show that 1) in the recent 70 years, the frequency of typhoon generation has slowly decreased, while the frequency of landing typhoons in China has slowly increased;2) typhoon frequency has varying degrees of negative correlation with the intensity of subtropical high in different regions of the northern hemisphere, especially with the area index and intensity index of the South China Sea subtropical high;3) in July 2020, the area and intensity of the subtropical high in the Northwest Pacific were abnormally large and strong. Easterly winds prevailed in the tropics, and the cross-equatorial airflow was weak, resulting in a severe reduction in the frequency of typhoon generation, leading to “no-typhoon” events.
文摘Tropical Cyclone (TC) activity is an important feature of China's climate that can have important impacts on precipitation and can cause extensive property damage. In particular, precipitation from TCs contributes a significant portion of overall precipitation. This study deals with typhoons that influence China and focuses on their impact on China's precipitation. Four aspects are examined in this research. Firstly, the study of influencing typhoon frequency reveals that the main season that typhoons affect China is from May to November, especially between July and September. The frequency of influencing typhoons was steady during the past 40 years. Secondly, inspection of the climatology of station typhoon precipitation shows that Hainan and the southeastern coastalmost regions are most frequently affected by typhoons, and most of the regions south of the Yangtze River are affected by typhoons each year. Meanwhile, during 1957-1996, most of the typhoon-influenced regions show decreasing trends in typhoon precipitation but only the trends in southern Northeast China are significant. Thirdly, examination of the typhoon cases shows that there exists it significant linear relationship between the precipitation volume and impacted area. Finally, study of variations of typhoon impacts on China's precipitation suggests that there exists a decreasing trend in the contribution of typhoon precipitation to overall precipitation, while total annual volume of typhoon precipitation decreases significantly during the period.
文摘Typhoons with erratic movement are studied for their annual frequency of occurrence over the South China Sea and Northwest Pacific,based on 102 years of data (1884—1985).It discovers that the years with higher fre- quency tend to get together.There are well-defined periods of 12 and 30 years,revealed with the maximum entropy method (MEM),the latter of low-frequency oscillation being clearer.
