Studies on the impact of solar activity on climate system are very important in understanding global climate change. Previous studies in this field were mostly focus on temperature, wind and geopotential height. In th...Studies on the impact of solar activity on climate system are very important in understanding global climate change. Previous studies in this field were mostly focus on temperature, wind and geopotential height. In this paper, interdecadal correlations of solar activity with Winter Snow Depth Index （WSDI） over the Tibetan Plateau, Arctic Oscillation Index （AOI） and the East Asian Winter Monsoon Index （EAWMI） are detected respectively by using Solar Radio Flux （SRF）, Total Solar Irradiance （TSI） and Solar Sunspot Number （SSN） data and statistical methods. Arctic Oscillation and East Asian winter monsoon are typical modes of the East Asian atmospheric circulation. Research results show that on inter-decadal time scale over 11-year solar cycle, the sun modulated changes of winter snow depth over the Tibetan Plateau and East Asian atmospheric circulation. At the fourth lag year, the correlation coefficient of SRF and snow depth is 0.8013 at 0.05 significance level by Monte-Carlo test method. Our study also shows that winter snow depth over the Tibetan Plateau has significant lead and lag correlations with Arctic Oscillation and the East Asian winter monsoon on long time scale. With more snow in winter, the phase of Arctic Oscillation is positive, and East Asian winter monsoon is weak, while with less snow, the parameters are reversed. An example is the winter of 2012/2013, with decreased Tibetan Plateau snow, phase of Arctic Oscillation was negative, and East Asian winter monsoon was strong.展开更多
This paper obtained a set of consecutive and long-recorded observational snow depth data from 51 observation stations by choosing, removing and interpolating original observation data over the Tibetan Plateau for 1961...This paper obtained a set of consecutive and long-recorded observational snow depth data from 51 observation stations by choosing, removing and interpolating original observation data over the Tibetan Plateau for 1961-2006. We used monthly precipitation and temperature data from 160 stations in China for 1951-2006, which was collected by the National Climate Center. Through calculating and analyzing the correlation coefficient, significance test, polynomial trend fitting, composite analysis and abrupt change test, this paper studied the interdecadal change of winter snow over the Tibetan Plateau and its relationship to summer pre- cipitation and temperature in China, and to tropospheric atmospheric temperature. This paper also studied general circulation and East Asian summer monsoon under the background of global warming.展开更多
Two hailstorms that occurred in Beijing and Tianjin,respectively,are investigated,based mainly on the total lightning data observed by the System d＇Alerte Fondre par Interferometric Radioelecctrique（SAFIR3000）,the ...Two hailstorms that occurred in Beijing and Tianjin,respectively,are investigated,based mainly on the total lightning data observed by the System d＇Alerte Fondre par Interferometric Radioelecctrique（SAFIR3000）,the cloud-to-ground（CG） lightning data of a CG lightning location system,and the echo data of a Doppler radar.Both hailstorms exhibited two lightning frequency peaks：the first was before the hailfall and the second was after the hailfall,with the second peak greater than the first.The dominant polarity of the CG lightning was positive in the stage around the first frequency peak,but changed to negative in the stage around the second frequency peak.The evolution of radar echoes and the height distribution of lightning radiation sources are explored,revealing that both hailstorms had stronger convection and the main positive charge occurred at mid levels during the stage around the first frequency peak.However,whilst the Beijing hailstorm experienced the enhancement of convection,with the main positive charge at upper levels around the second frequency peak,the Tianjin hailstorm generated its second frequency peak during the period when the convection kept weakening and the main positive charge dropped to mid-lower levels.Through evaluation of the radar parameters,we investigate the mechanisms responsible for the second stage of active lightning discharge.Furthermore,the lightning activity exhibited a close relationship with radar echo parameters and hailfall.Lightning jump signals were found before the hailfall and were associated with the change ratio of the 40-dBZ echo volume above the-15℃ level,which demonstrates the application value of lightning data in severe weather warning.展开更多
基金funded by the National Science Foundation of China (No. 41575091)the National Basic Research and Development (973) Program of China (Grant No. 2012CB957803 and No. 2012CB957804)
文摘Studies on the impact of solar activity on climate system are very important in understanding global climate change. Previous studies in this field were mostly focus on temperature, wind and geopotential height. In this paper, interdecadal correlations of solar activity with Winter Snow Depth Index （WSDI） over the Tibetan Plateau, Arctic Oscillation Index （AOI） and the East Asian Winter Monsoon Index （EAWMI） are detected respectively by using Solar Radio Flux （SRF）, Total Solar Irradiance （TSI） and Solar Sunspot Number （SSN） data and statistical methods. Arctic Oscillation and East Asian winter monsoon are typical modes of the East Asian atmospheric circulation. Research results show that on inter-decadal time scale over 11-year solar cycle, the sun modulated changes of winter snow depth over the Tibetan Plateau and East Asian atmospheric circulation. At the fourth lag year, the correlation coefficient of SRF and snow depth is 0.8013 at 0.05 significance level by Monte-Carlo test method. Our study also shows that winter snow depth over the Tibetan Plateau has significant lead and lag correlations with Arctic Oscillation and the East Asian winter monsoon on long time scale. With more snow in winter, the phase of Arctic Oscillation is positive, and East Asian winter monsoon is weak, while with less snow, the parameters are reversed. An example is the winter of 2012/2013, with decreased Tibetan Plateau snow, phase of Arctic Oscillation was negative, and East Asian winter monsoon was strong.
基金supported by the Ministry of Science and Technology Project under No.2012CB957803 and No. 2007BAC29B02Special Fund on Climate Change of China Meteorological Administration under Grant No. CCSF2007-2C
文摘This paper obtained a set of consecutive and long-recorded observational snow depth data from 51 observation stations by choosing, removing and interpolating original observation data over the Tibetan Plateau for 1961-2006. We used monthly precipitation and temperature data from 160 stations in China for 1951-2006, which was collected by the National Climate Center. Through calculating and analyzing the correlation coefficient, significance test, polynomial trend fitting, composite analysis and abrupt change test, this paper studied the interdecadal change of winter snow over the Tibetan Plateau and its relationship to summer pre- cipitation and temperature in China, and to tropospheric atmospheric temperature. This paper also studied general circulation and East Asian summer monsoon under the background of global warming.
基金Supported by the National(Key)Basic Research and Development(973)Program of China(2014CB441402)Basic Research Project of the Chinese Academy of Meteorological Sciences(2014R017 and 2013Z006)+1 种基金Key Laboratory Open Project of Disasters Research(2014LASW-B08)Natural Science Research for Jiangsu Provincial Higher Education Colleges(14KJA170005)
文摘Two hailstorms that occurred in Beijing and Tianjin,respectively,are investigated,based mainly on the total lightning data observed by the System d＇Alerte Fondre par Interferometric Radioelecctrique（SAFIR3000）,the cloud-to-ground（CG） lightning data of a CG lightning location system,and the echo data of a Doppler radar.Both hailstorms exhibited two lightning frequency peaks：the first was before the hailfall and the second was after the hailfall,with the second peak greater than the first.The dominant polarity of the CG lightning was positive in the stage around the first frequency peak,but changed to negative in the stage around the second frequency peak.The evolution of radar echoes and the height distribution of lightning radiation sources are explored,revealing that both hailstorms had stronger convection and the main positive charge occurred at mid levels during the stage around the first frequency peak.However,whilst the Beijing hailstorm experienced the enhancement of convection,with the main positive charge at upper levels around the second frequency peak,the Tianjin hailstorm generated its second frequency peak during the period when the convection kept weakening and the main positive charge dropped to mid-lower levels.Through evaluation of the radar parameters,we investigate the mechanisms responsible for the second stage of active lightning discharge.Furthermore,the lightning activity exhibited a close relationship with radar echo parameters and hailfall.Lightning jump signals were found before the hailfall and were associated with the change ratio of the 40-dBZ echo volume above the-15℃ level,which demonstrates the application value of lightning data in severe weather warning.
