To better understand climate variations of Meiyu, some new indicators for theonset and retreat dates, duration, and Meiyu precipitation in the Yangtze-Huaihe River valley areobjectively developed by using observed dai...To better understand climate variations of Meiyu, some new indicators for theonset and retreat dates, duration, and Meiyu precipitation in the Yangtze-Huaihe River valley areobjectively developed by using observed daily precipitation data from 230 stations in eastern Chinaduring 1954-2003. The rainy season onset and retreat dates in each station can be denned in terms ofthresholds for rainfall intensity and persistence. Then, the onset and retreat dates of the Meiyufor the Yangtze-Huaihe River basin have been determined when more than 40% of stations reach thefirst rainy season thresholds in the study region. Based on the indicators of Meiyu in theYangtze-Huaihe River basin, variations of Meiyu rainfall during 1954-2003 are analyzed. The resultssuggest that Meiyu rainfall in the Yangtze-Huaihe River basin has increased in recent 50 years. Inaddition, interannual and interdecadal variability of Meiyu is also obvious. All the indicatorsdisplay a predominant period of about 3 years.展开更多
Meiyu onset (MO) over Yangtze-Huaihe River Valley (YHRV) possesses obvious characteristics of interannual variations. Based on NCEP/NCAR reanalysis data sets, NOAA OLR and ERSST data, the in-terannual variability of M...Meiyu onset (MO) over Yangtze-Huaihe River Valley (YHRV) possesses obvious characteristics of interannual variations. Based on NCEP/NCAR reanalysis data sets, NOAA OLR and ERSST data, the in-terannual variability of MO(IVMO) and its previous strong influence signal (PSIS) are investigated. The possible mechanisms that the PSIS affecting IVMO are also discussed. The results show that the pre-vious CP-ENSO (Central Pacific El Nio/Southern Oscillation) event is the PSIS affecting IVMO and it has a better accuracy rate of short-term climate prediction and practicality. The MO is most likely to be late (early) with the warm (cold) phase of CP-ENSO in previous boreal February and spring. CP-ENSO affects MO mainly by means of EAP (East Asian-Pacific) or JP (Japanese-Pacific) teleconnection, in which the tropical western North Pacific anticyclone plays an important role. In the years of CP-ENSO warm phase, the tropical warm wet water vapor transportation to YHRV is late. The anomalous positive sea surface temperature near the equatorial central Pacific results in late northward jump of the western Pacific subtropical high and late establishment of Indian southwest monsoon via air-sea interaction, which leads to late seasonal transition of the atmospheric circulations over East Asia from boreal spring to summer. Late seasonal transition of the atmospheric circulations and late tropical warm wet water vapor transport to YHRV are the primary reasons that cause the late MO. The situations are directly opposite in the years of CP-ENSO cold phase.展开更多
By using BCC_RegCM 1.0 (RegCM for short) from Beijing Climate Center (BCC), China Meteorological Administration (CMA), the Meiyu season characters over the Yangtze-Huaihe region during 1991-2005 are simulated. The maj...By using BCC_RegCM 1.0 (RegCM for short) from Beijing Climate Center (BCC), China Meteorological Administration (CMA), the Meiyu season characters over the Yangtze-Huaihe region during 1991-2005 are simulated. The major conclusions of this study may be summarized as the following: (1) RegCM can reproduce the interannual variation and the spatial distribution of the summertime precipitation and temperature in the Yangtze-Huaihe region. (2) By use of a generalized Meiyu criterion and in accordance with model-calculated precipitation and temperature, the Meiyu onset and ending date have been determined. Compared with the observation, RegCM can simulate the interannual variation of the Yangtze-Huaihe Meiyu with preferable capability for most of the normal Meiyu years (such as 1995, 1997, 2000, 2001, 2002 and 2004), especially for the rich Meiyu years of 1996, 1998 and 1999. (3) In terms of the average simulation for the recent 15 years, the timings of onset and ending of Meiyu occur on June 1 and July 13, respectively, which are earlier than the climatological observation. For duration, Meiyu persists for 32 d, 3 d shorter than the observation. The index of Meiyu intensity is 2.45, while the climatological one is 3.00. Therefore, RegCM is capable of simulating the climatological Meiyu duration and intensity, while the capability of simulating the onset and ending date of Meiyu still needs to be improved.展开更多
基金Sponsored by the "Interannual and Interdecadal Variations and Their Mechanisms over Yangtze-Huaihe River Basin" of NSFCKey Project under Grant No. 40233037.
文摘To better understand climate variations of Meiyu, some new indicators for theonset and retreat dates, duration, and Meiyu precipitation in the Yangtze-Huaihe River valley areobjectively developed by using observed daily precipitation data from 230 stations in eastern Chinaduring 1954-2003. The rainy season onset and retreat dates in each station can be denned in terms ofthresholds for rainfall intensity and persistence. Then, the onset and retreat dates of the Meiyufor the Yangtze-Huaihe River basin have been determined when more than 40% of stations reach thefirst rainy season thresholds in the study region. Based on the indicators of Meiyu in theYangtze-Huaihe River basin, variations of Meiyu rainfall during 1954-2003 are analyzed. The resultssuggest that Meiyu rainfall in the Yangtze-Huaihe River basin has increased in recent 50 years. Inaddition, interannual and interdecadal variability of Meiyu is also obvious. All the indicatorsdisplay a predominant period of about 3 years.
基金Supported jointly by the China Meteorological Administration Project (Grant No. GYHY200706005)the Applied Basic and Front Technology Research Project for Tianjin (Grant No. 08JCYBJC10300)the Technological Innovation Foundation Program of Beijing Regional Meteorological Center (Grant No. BRMCCJ200705)
文摘Meiyu onset (MO) over Yangtze-Huaihe River Valley (YHRV) possesses obvious characteristics of interannual variations. Based on NCEP/NCAR reanalysis data sets, NOAA OLR and ERSST data, the in-terannual variability of MO(IVMO) and its previous strong influence signal (PSIS) are investigated. The possible mechanisms that the PSIS affecting IVMO are also discussed. The results show that the pre-vious CP-ENSO (Central Pacific El Nio/Southern Oscillation) event is the PSIS affecting IVMO and it has a better accuracy rate of short-term climate prediction and practicality. The MO is most likely to be late (early) with the warm (cold) phase of CP-ENSO in previous boreal February and spring. CP-ENSO affects MO mainly by means of EAP (East Asian-Pacific) or JP (Japanese-Pacific) teleconnection, in which the tropical western North Pacific anticyclone plays an important role. In the years of CP-ENSO warm phase, the tropical warm wet water vapor transportation to YHRV is late. The anomalous positive sea surface temperature near the equatorial central Pacific results in late northward jump of the western Pacific subtropical high and late establishment of Indian southwest monsoon via air-sea interaction, which leads to late seasonal transition of the atmospheric circulations over East Asia from boreal spring to summer. Late seasonal transition of the atmospheric circulations and late tropical warm wet water vapor transport to YHRV are the primary reasons that cause the late MO. The situations are directly opposite in the years of CP-ENSO cold phase.
基金supported by the National Natural Science Foundation of China (Grant No. 40705026)Guangzhou Regional Meteorological Center’s Programs for Science and Technology Development (Grant No. GRMC 2007B01)
文摘By using BCC_RegCM 1.0 (RegCM for short) from Beijing Climate Center (BCC), China Meteorological Administration (CMA), the Meiyu season characters over the Yangtze-Huaihe region during 1991-2005 are simulated. The major conclusions of this study may be summarized as the following: (1) RegCM can reproduce the interannual variation and the spatial distribution of the summertime precipitation and temperature in the Yangtze-Huaihe region. (2) By use of a generalized Meiyu criterion and in accordance with model-calculated precipitation and temperature, the Meiyu onset and ending date have been determined. Compared with the observation, RegCM can simulate the interannual variation of the Yangtze-Huaihe Meiyu with preferable capability for most of the normal Meiyu years (such as 1995, 1997, 2000, 2001, 2002 and 2004), especially for the rich Meiyu years of 1996, 1998 and 1999. (3) In terms of the average simulation for the recent 15 years, the timings of onset and ending of Meiyu occur on June 1 and July 13, respectively, which are earlier than the climatological observation. For duration, Meiyu persists for 32 d, 3 d shorter than the observation. The index of Meiyu intensity is 2.45, while the climatological one is 3.00. Therefore, RegCM is capable of simulating the climatological Meiyu duration and intensity, while the capability of simulating the onset and ending date of Meiyu still needs to be improved.
