UWTA是指南半球热带非洲区域300hPa上空的暖异常（Figure1）。 上层暖异常可使区域地面气压增强以加强区域垂直运动，从而与坦桑尼亚3-5月强降水有密切的关系，那么ENSO在多大程度上能影响到上层暖异常的形成呢？如何影响？

本研究分析发现ENSO年际变率与3-5月UWTA有较密切的关系，且以前期冬季相关最强，但不同季节ENSO对于UWTA形成的机制不同。热带中东太平洋海温超前于UWTA形成 6个月，秋冬季ENSO暖位相对应热带印度洋暖海温异常，首先通过沃克环流异常使印度洋区域海温增暖；秋冬季热带印度洋暖海温区对流加强，沃克环流上升支垂直运动增强，对流通过非绝热潜热释放加热高层大气并平流到坦桑尼亚上空从而有利于UWTA的形成；同时，由ENSO相关海温引起的哈德来环流在秋冬季呈对称特性，到次年春季则呈非对称性。3-5月非对称的哈德来环流从印度洋暖洋面上空向坦桑尼亚区域上空输送暖湿气流从而有利于UWTA的形成（Figure 2）。ENSO对后期3-5月ＵＷＴＡ的影响有助于理解坦桑尼亚及东非强降水发生的背景机制，ENSO超前3-6个月的显著关系对于强降水的预测及防御也有重要的意义。相关成果已在《International Journal of Climatology》期刊上发表。

Figure1 The first EOF mode (EOF1) of the mean MAM 300 hPa temperature anomaly in (a) and its corresponding time series coefficient (PC1) in (b) during MAM of 1980–2010. EOF1 explains 94.05% of the total variance

Figure2 The composite vertical cross-section distribution fields for the meridional-vertical circulation anomalies (hPa; in vectors) and diabatic (adiabatic) heating (K_day−1, in contour lines) along 75_E being the differences between warm and cold phase of ENSO during the previous SON. The shaded areas are statistically significant at 5% level with a two tailed Student's t test

相关文献：

Mafuru KB, Guirong T. The influence of ENSO on the upper warm temperature anomaly formation associated with the March–May heavy rainfall events in Tanzania. Int J Climatol. 2019;1–19. https://doi.org/10.1002/ joc.6364

Mafuru K B , Guirong T . Assessing Prone Areas to Heavy Rainfall and the Impaction of the Upper Warm Temperature Anomaly during March–May Rainfall Season in Tanzania[J]. Advances in Meteorology, 2018, 2018:1-17.DOI: 10.1155/2018/8353296