中国南方旱涝年际年代际变化及成因研究进展

基于气候变暖背景下中国南方旱涝时空格局发生变化的基本事实，回顾了中国南方降水的主要模态和旱涝年际年代际尺度变化特征及其成因的主要研究进展。研究指出，El Ni?o发展年，中国南方大部地区降水偏少，尤其在长江及其以南地区，而El Ni?o衰减年则相反。强调热带印度洋海盆一致偏暖使西太平洋副热带高压增强，位置偏南，导致西北太平洋反气旋异常的形成和维持，有利于中国南方降水加强。青藏高原冬春季积雪多，春夏季高原感热和上升运动较弱，导致夏季风偏弱，有利于长江流域降水偏多易涝，反之亦然。关于多因子协同作用对南方旱涝影响，指出南方旱涝是多因子协同影响的结果, 如菲律宾反气旋受冬季青藏高原积雪、El Ni?o与前期春季印度洋海温等多因子协同影响。南方旱涝与影响因子发生了年际关系的年代际变化，在气候变暖背景下，随着后者的年代际转型，其对前者的影响关系也发生了年代际变化。因此，提出了应该关注南方旱涝的预测策略与方法，提高旱涝预测技巧。

Recent Research Advances on the Interannual interdecadal Variations of Drought/Flood in South China and Associated Causes

Based on changes of spatial-temporal distribution of flood and drought in South China under global warming, the recent research progress on characteristics of inter-annual and inter-decadal variations of drought/flood and associated causes are reviewed. It's found there will be less precipitation in South China especially for the Yangtze valley in the developing phase of El Ni?o, while more precipitation in the decay phase. During the above process, the basin wide warming in tropical Indian Ocean are found to intensify the Northwestern Pacific subtropical high and shift it to a more southward position, leading to the occurrence of low-level anticyclone circulation over Northwestern Pacific, which would affect the precipitation of South China through adjusting the southerly and moisture transportation. The snow cover of the Tibet Plateau is also found as a key factor, when more snow cover occurs in spring-winter, the sensible heat flux is too weak to heat troposphere, which would reduce the meridional temperature gradient to cause a weak summer monsoon and more precipitation over the Yangtze valley, and vice versa. For synergistic effects of multi-factors on the occurrence of flood and drought in South China, results indicate it's impacted by multiple factors and cannot be dominated by one single factor. For example, the Philippine anticyclone can be impacted by the winter Tibet Plateau snow cover, El Ni?o and basin wide warming of tropical Indian Ocean. For the inter-decadal variation of the inter-annual relationship between flood and drought in South China and their influencing factors, strong inter-decadal variation on the relationship between the influencing factors and flood/drought are found, when these factors exhibit a strong inter-decadal variation. For example, the relationship between tropical Pacific Ocean and South China precipitation is found loose in recent decades, while the influence of Indian Ocean sea surface temperature anomaly on South China is intensified. Based on the aforementioned results, it suggests more attentions being focused on the prediction strategy and method for South China to improve the predictability of drought and flood.