Sea Surface Temperature-Forced Monsoon Evolution and Variability in West Africa

西非季风在短暂但强烈的雨季为萨赫勒地区提供了大部分年降雨量。由于就人口参与率而言，农业仍然是主要的经济活动，了解和预测季风季的大小和时间的变化尤其重要，如果没有做好准备，可能会造成毁灭性的影响。这项工作将直接有助于改进季风降雨量的季节到年际预报。这项工作的结果将与国际气候与社会研究所等有意帮助萨赫勒地区的气候预测组织及其在西非的长期合作伙伴密切相关。通过各种渠道，这项研究提供的信息可以为应用程序提供信息；为萨赫勒地区更好地决策提供气候信息。这项工作还将支持一名研究生。这项研究收集的知识还将有助于哥伦比亚大学国际与公共事务学院(SIPA)的气候与社会课程的教学。该项目的目标是改善对西非夏季风的了解和预测，特别是对周围热带海洋海面温度变化的反应。关于海表面温度波动的信息经常可用，对气候预测很重要。萨赫勒季风雨的季节性降雨量每年不同，有时会降至干旱水平，对社会造成严重影响。这种变化与偏远和附近海域的海面温度波动有关。过去的研究表明，当东热带太平洋海面温度相对较高时，夏季季风雨往往会减弱，有时甚至会停止。在拉尼娜期间，当东热带太平洋相对凉爽时，降雨往往强烈而充足。然而，这种联系并不稳定，因为该地区对热带大西洋和印度洋等其他盆地的温度变化也很敏感。利用全球大气气候模式，在全球海洋中规定了不同的海洋表面温度情景，以模拟观测中发现的情况，这项研究将阐明季风如何对不同盆地的本地和远程海洋表面温度变化做出反应，分别和共同作用。通过了解作为时间函数的动量、热量和水汽输送的响应模式和机制，预计将提高基于季前海表面温度条件预报季风降雨的可能性。该实验方法还提供了季风降雨中“信噪比”的测量方法。将观测放在这个角度将有助于更好地确定预测的不确定性，也有助于提高季风季预测的质量。

The West African monsoon delivers most of the annual rainfall to the Sahel region in a short but intense rainy season. Since agriculture remains the dominant economic activity in terms of percent of population engaged, understanding and predicting the variability in both the magnitude and timing of the monsoon season is especially important and potentially devastating if not prepared for. This work;will directly contribute to improving seasonal to interannual prediction of monsoon rainfall. The results of this work will be highly relevant to climate prediction organizations interested in helping the Sahel such as the International Research Institute for Climate and Society and its long-standing partners in West Africa. Through various channels, information from the study can inform applications;of climate information for better decision-making in the Sahel. The work will also support a graduate student. Knowledge gathered from this study will also contribute to the teaching of climate and society in the School for International and Public Affairs (SIPA) at Columbia University programs.The goal of this project is to improve the understanding and prediction of the West African summer monsoon, specifically response to changes in sea surface temperatures in the surrounding tropical oceans. Information on sea surface temperature fluctuations is routinely available and is important for climate prediction. The seasonal amount of Sahel monsoon rains, varies from year to year sometimes dropping to drought levels with serious effects on society. This variability has been linked to sea surface temperature fluctuations in remote and nearby ocean areas. Past studies have shown a that summer monsoon rains tend to weaken and sometimes fail when eastern tropical Pacific sea surface temperatures are relatively warm, a state known as the El Niño. Rains tend to be strong and plentiful when the east tropical pacific are relatively cool, during the La Nina phase. However, this association is not steady because the region is also sensitive to temperature changes in other basins, such as the tropical Atlantic and the Indian Oceans. Utilizing an atmospheric global climate model, in which different sea surface temperature scenarios are prescribed in the global ocean mimicking what is found in observations, this research will elucidate how the monsoon responds to changes in local and remote sea surface temperature changes in different basins, acting separately and together. By understanding the response pattern and the mechanisms of momentum, heat and moisture transport as a function of time, it is anticipated that possibilities of prediction of monsoon rainfall, based on pre-season sea surface temperatures conditions, will be advanced. This experimental method also provides a measure of "signal-to-noise" ratio in the monsoon rainfall. Putting the observations in that perspective will help frame better the prediction uncertainties, also helping advance the quality of monsoon season prediction.