Solar Influences on Tropical Deep Convection and the Madden-Julian Oscillation (MJO): Observational Analyses and Tests of a Proposed Mechanism

该项目的目标是利用现有观测资料评估短期太阳紫外线变率（主要发生在太阳自转时间尺度约为27天的范围内）是否能影响从数周到数月的时间尺度上的热带气候变率。它将特别探讨以前报告的太平洋热带地区这种影响的证据是否确实有力。 统计分析将采用在太阳活动最大期条件下总共20年的太阳紫外线辐射测量数据，因为27天的变化特别大。 将分析对流层附近的温度和风等气象场，以确定短期太阳紫外线强迫是否会显著扰动热带对流层上层的层结，从而改变深对流的环境条件。 将研究对天气和大尺度环流的相关影响。PI还将探讨这种对27天太阳活动的反应是否取决于季节或厄尔尼诺/南方涛动的阶段以及平流层准两年期振荡。 将使用标准方法评估任何检测到的反应的统计学显著性。 确认太阳对热带对流和短期气候变率的重大短期影响将（a）为测试包括太阳强迫在内的气候模型提供新的观测;（B）改进长期天气预报;（c）增进我们对短期气候变率的了解。该项目将支持一名研究生和一名本科生。

The objective of this project is to apply available observations to evaluate whether short-term solar ultraviolet variability (occurring mainly on the ~ 27-day solar rotation time scale) can influence tropical climate variability on time scales from weeks to months. It will specifically explore whether previously reported evidence for such an influence in the tropical Pacific sector is indeed robust. Statistical analyses will employ a total of 20 years of solar ultraviolet radiation measurements under solar maximum conditions when 27-day variations are especially large. Coincident meteorological fields such as temperature and wind near the troposphere will be analyzed to determine whether short-term solar ultraviolet forcing can significantly perturb the stratification of the tropical upper troposphere and thereby modify the environment condition for deep convections. Associated effects on synoptic and large-scale circulations will be investigated. The PI will also explore whether such responses to the 27-day solar depend on season or on the phases of the El-Niño/Southern Oscillation as well as the stratospheric quasi-biennial oscillation. The statistical significance of any detected responses will be assessed using standard methods. Confirmation of a significant short-term solar impact on tropical convection and short-time climate variability would (a) provide a new observation for testing climate models that include solar forcing; (b) lead to improvements in extended-range weather forecasting; and (c) improve our understanding of short-time climate variability. The project will support one graduate student and one undergraduate student.