利用NOAA(National Oceanic and Atmospheric Administration)海温、GPCP(Global Precipitation Climatology Project)降水和ERA-20C(ECMWF's first atmospheric reanalysis of the 20th century)再分析大气环流资料,结合大气环流模...利用NOAA(National Oceanic and Atmospheric Administration)海温、GPCP(Global Precipitation Climatology Project)降水和ERA-20C(ECMWF's first atmospheric reanalysis of the 20th century)再分析大气环流资料,结合大气环流模式ECHAM5敏感性试验,研究了与秋季印度洋海温偶极子模态(IOD)相联系的冬季热带西太平洋海温异常型及其对东亚冬季气候的影响。发现在秋季发生IOD背景下,冬季西太平洋存在两类海温异常的变化型:一类是西太平洋区域一致偏暖/冷的模态,另一类是区域西冷东暖/西暖东冷的模态。尽管西太平洋海温一致偏暖和西冷东暖这两类海温变化型均有利于华南冬季少降水,但影响的范围有所不同。一致偏暖型引起的少降水范围较大,从华南扩展到长江中下游地区。西冷东暖型引起少降水范围主要限于华南,而在长江中下游到华北则降水偏多。相应地,在大气环流上,尽管两类海温异常型均有利于在西北太平洋菲律宾海附近出现气旋式环流异常,但气旋的强度和中心位置有差异。一致偏暖型引起的气旋偏强,中心位置偏西,其后部异常东北风控制的范围更大,导致少降水范围更大,而西冷东暖型引起的气旋偏弱,中心位置偏东,其后部异常东北风控制的范围小,导致少降水区域主要在华南沿海。本文结果对认识IOD调制随后冬季东亚降水异常的机理有重要意义。展开更多
Based on the reconstructed precipitation series in North China from historical documents, the 1876-1878 drought was identified as the most severe and extreme one in North China over the past 300 years. Meanwhile, the ...Based on the reconstructed precipitation series in North China from historical documents, the 1876-1878 drought was identified as the most severe and extreme one in North China over the past 300 years. Meanwhile, the spatial patterns of seasonal and annual precipitation during 1876-1877 were analyzed and the social and economic impacts related with this drought event were evaluated according to the descriptions in the historical documents. The results indicated that this long-lasting drought started by the spring of 1876 and did not stop until the spring of 1878. Within the three years, the harvest failures brought the rice price increased to 5-10 times than that in the normal year, and the total population in the five provinces over North China decreased by more than 20 million due to a large number of dead people and migrations. In addition, related investigations suggested that the 1876-1878 drought was prevalent worldwide, which has possible link with abnormal high SST in the equatorial central and eastern Pacific, strong El Nio episode and positive AAO anomalies.展开更多
The relationships between the evolution of two types of El Ni?o events and the subsurface ocean temperature anomaly(SOTA) in the equatorial Pacific are compared in this study. The results show that both types of El Ni...The relationships between the evolution of two types of El Ni?o events and the subsurface ocean temperature anomaly(SOTA) in the equatorial Pacific are compared in this study. The results show that both types of El Ni?o are negatively correlated to the SOTA in the equatorial western Pacific, but relationships are different in different phases of El Ni?o. Furthermore, the occurrence of different types of El Ni?o is related to different features of the equatorial thermocline, e.g. its zonal gradient, significant variation area, amplitude and duration of thermocline oscillation. The propagation of SOTA in the equator plays an important role during the evolution of both types of El Ni?o, but shows dramatic differences in intensity, duration and phase reverse of warm SOTA. Moreover, the pathways of SOTA signal are different between these two types of El Ni?o. The dominant pathway in the life cycle of Eastern Pacific(EP)-El Ni?o lies on the equator and to its north, but there is no loop to the south of the equator. In contrast, the dominant pathway in Central Pacific(CP)-El Ni?o is located on the equator and to its south, and the propagation signal of SOTA to the north of the equator is very weak.The relationships between the zonal wind anomalies and the two types of El Ni?o are also preliminarily discussed. It is shown that EP-El Ni?o is more likely to respond to the westerly anomalies over the equatorial central and western Pacific, while CP-El Ni?o is more likely to respond to the westerly anomalies over the equatorial western Pacific and need the cooperation of easterly anomalies over the equatorial eastern Pacific to certain extent.展开更多
文摘利用NOAA(National Oceanic and Atmospheric Administration)海温、GPCP(Global Precipitation Climatology Project)降水和ERA-20C(ECMWF's first atmospheric reanalysis of the 20th century)再分析大气环流资料,结合大气环流模式ECHAM5敏感性试验,研究了与秋季印度洋海温偶极子模态(IOD)相联系的冬季热带西太平洋海温异常型及其对东亚冬季气候的影响。发现在秋季发生IOD背景下,冬季西太平洋存在两类海温异常的变化型:一类是西太平洋区域一致偏暖/冷的模态,另一类是区域西冷东暖/西暖东冷的模态。尽管西太平洋海温一致偏暖和西冷东暖这两类海温变化型均有利于华南冬季少降水,但影响的范围有所不同。一致偏暖型引起的少降水范围较大,从华南扩展到长江中下游地区。西冷东暖型引起少降水范围主要限于华南,而在长江中下游到华北则降水偏多。相应地,在大气环流上,尽管两类海温异常型均有利于在西北太平洋菲律宾海附近出现气旋式环流异常,但气旋的强度和中心位置有差异。一致偏暖型引起的气旋偏强,中心位置偏西,其后部异常东北风控制的范围更大,导致少降水范围更大,而西冷东暖型引起的气旋偏弱,中心位置偏东,其后部异常东北风控制的范围小,导致少降水区域主要在华南沿海。本文结果对认识IOD调制随后冬季东亚降水异常的机理有重要意义。
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-YW-315-2)the National Natural Science Foundation of China (40701021 and 40625002)the National Key Technology R&D Program of China (2007BAC03A01)
文摘Based on the reconstructed precipitation series in North China from historical documents, the 1876-1878 drought was identified as the most severe and extreme one in North China over the past 300 years. Meanwhile, the spatial patterns of seasonal and annual precipitation during 1876-1877 were analyzed and the social and economic impacts related with this drought event were evaluated according to the descriptions in the historical documents. The results indicated that this long-lasting drought started by the spring of 1876 and did not stop until the spring of 1878. Within the three years, the harvest failures brought the rice price increased to 5-10 times than that in the normal year, and the total population in the five provinces over North China decreased by more than 20 million due to a large number of dead people and migrations. In addition, related investigations suggested that the 1876-1878 drought was prevalent worldwide, which has possible link with abnormal high SST in the equatorial central and eastern Pacific, strong El Nio episode and positive AAO anomalies.
基金supported by the National Basic Research Program of China (2013CB956203)
文摘The relationships between the evolution of two types of El Ni?o events and the subsurface ocean temperature anomaly(SOTA) in the equatorial Pacific are compared in this study. The results show that both types of El Ni?o are negatively correlated to the SOTA in the equatorial western Pacific, but relationships are different in different phases of El Ni?o. Furthermore, the occurrence of different types of El Ni?o is related to different features of the equatorial thermocline, e.g. its zonal gradient, significant variation area, amplitude and duration of thermocline oscillation. The propagation of SOTA in the equator plays an important role during the evolution of both types of El Ni?o, but shows dramatic differences in intensity, duration and phase reverse of warm SOTA. Moreover, the pathways of SOTA signal are different between these two types of El Ni?o. The dominant pathway in the life cycle of Eastern Pacific(EP)-El Ni?o lies on the equator and to its north, but there is no loop to the south of the equator. In contrast, the dominant pathway in Central Pacific(CP)-El Ni?o is located on the equator and to its south, and the propagation signal of SOTA to the north of the equator is very weak.The relationships between the zonal wind anomalies and the two types of El Ni?o are also preliminarily discussed. It is shown that EP-El Ni?o is more likely to respond to the westerly anomalies over the equatorial central and western Pacific, while CP-El Ni?o is more likely to respond to the westerly anomalies over the equatorial western Pacific and need the cooperation of easterly anomalies over the equatorial eastern Pacific to certain extent.
