Collaborative Research: Linking the Long-Term Congo Drought to Changes in Walker-Type Circulations Affecting Equatorial Africa

合作研究：将刚果长期干旱与影响赤道非洲的沃克型环流的变化联系起来

• 批准号: 1854486
• 负责人: Liming Zhou
• 金额: $ 59.84万
• 依托单位: SUNY at Albany
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1854486&HistoricalAwards=false
• 关键词: Collaborative; Research; Linking; Long; Term

The Basin of the Congo river is home to the second largest rainforest in the world, which sustains a growing population and an abundance of plant and animal species. Despite its size, population, and importance as a biodiversity hotspots, the rainforest is not well represented in the climate research literature, particularly compared to the larger but less populous Amazon rainforest. In particular, recent short-term Amazon droughts have drawn worldwide attention to the vulnerability of tropical forests, but the Congo Basin has been in drought for several decades. The Congo Basin receives less rainfall than the Amazon, and paleoclimate data suggests that it has experienced dramatic forest loss during previous dry periods. The importance and potential vulnerability of the Congo rainforest thus motivate further study of the mechanisms which regulate climate and rainfall in the region.Work performed here seeks to determine the causes of the rainfall deficits in the region, in particular the extent to which they are driven by increases in the sea surface temperature (SST) of the adjacent oceans. Near-equatorial SST changes can affect continental precipitation through their effects on the large-scale atmospheric overturning circulations known as Walker cells. The research team will test the hypothesis that the drought is primarily due to SST increases in the Indian and Western Pacific oceans, which result in an intensified and westward-shifted Walker cell, which in turn induces subsidence over the Congo and reduces moisture transport into it. The research is conducted using a combination of observational data and model simulations. The team will take advantage of a rain gauge-based precipitation dataset for the Congo and surrounding regions from 1921 to 2014, compiled by one of the PIs under previous NSF support. Model simulations are performed using a fully-coupled atmosphere-ocean climate model, an atmosphere-only model with prescribed SSTs, and a "pacemaker" configuration in which SST is specified over a particular ocean region (say, the equatorial Indian ocean), but the coupled model determines its own SST outside the region.The work has broader impacts due to the importance and vulnerability of the Congo Basin rainforest, as noted above. A particular concern is that the SST increases in the Indian and Western Pacific Oceans may be due to anthropogenic greenhouse warming, in which case the rainfall reductions are unlikely to reverse. Results are communicated to African climate communities and non-profit organizations for use in climate impact assessments and the formulation of adaptation strategies. In addition, the project provides support and training to two graduate students and one undergraduate.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

刚果河流域是世界上第二大雨林的所在地，它维持着不断增长的人口和丰富的动植物物种。 尽管它的规模，人口和重要性作为生物多样性热点，热带雨林是没有很好地代表在气候研究文献中，特别是与较大但人口较少的亚马逊雨林相比。 特别是，最近亚马逊地区的短期干旱引起了全世界对热带森林脆弱性的关注，但刚果盆地已经干旱了几十年。 刚果盆地的降雨量比亚马逊河少，古气候数据表明，在以前的干旱时期，它经历了巨大的森林损失。 因此，刚果雨林的重要性和潜在的脆弱性促使人们进一步研究该地区气候和降雨的调节机制，在此开展的工作旨在确定该地区降雨不足的原因，特别是在多大程度上是由邻近海洋的海表温度（SST）升高造成的。 近赤道海温变化可以通过影响被称为步行者环流的大尺度大气翻转环流来影响大陆降水。该研究小组将测试干旱主要是由于印度洋和西太平洋的SST增加，这导致步行者环流增强并向西移动，从而导致刚果上空下沉并减少水分输送的假设。该研究将使用观测数据和模型模拟相结合进行。该团队将利用1921年至2014年刚果及周边地区基于雨量计的降水数据集，该数据集由一个PI在先前NSF的支持下编制。 模式模拟使用了一个完全耦合的大气-海洋气候模式，一个只包含指定SST的大气模式，以及一个“起搏器”配置，其中SST指定在特定的海洋区域（例如赤道印度洋），但耦合模式确定其自己的SST在该区域之外。如上所述，由于刚果盆地雨林的重要性和脆弱性，这项工作具有更广泛的影响。 一个特别令人关切的问题是，印度洋和西太平洋的海温上升可能是由于人为温室效应造成的，在这种情况下，降雨量的减少不太可能逆转。研究结果将传达给非洲气候社区和非营利组织，用于气候影响评估和制定适应战略。 此外，该项目还为两名研究生和一名本科生提供支持和培训。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Recent rainfall conditions in the Congo Basin

• DOI: 10.1088/1748-9326/ac61c4
• 发表时间: 2022-03
• 期刊: Environmental Research Letters
• 影响因子: 6.7
• 作者: S. Nicholson;D. Klotter;Liming Zhou;W. Hua

Rising Planetary Boundary Layer Height over the Sahara Desert and Arabian Peninsula in a Warming Climate

• DOI: 10.1175/jcli-d-20-0645.1
• 发表时间: 2021-02
• 期刊: Journal of Climate
• 影响因子: 4.9
• 作者: Liming Zhou;Yuhong Tian;Nan Wei;S. Ho;Jing Li

Increasing Influence of Indian Ocean Dipole on Precipitation Over Central Equatorial Africa

• DOI: 10.1029/2020gl092370
• 发表时间: 2021-04
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Yan Jiang;Liming Zhou;P. Roundy;W. Hua;A. Raghavendra

Relationships between intense convection, lightning, and rainfall over the interior Congo Basin using TRMM data

• DOI: 10.1016/j.atmosres.2022.106164
• 发表时间: 2022-08
• 期刊: Atmospheric Research
• 影响因子: 5.5
• 作者: Stephen L. Solimine;Liming Zhou;A. Raghavendra;Yichen Cai

Orographic enhancement of rainfall over the Congo Basin

• DOI: 10.1002/asl.1079
• 发表时间: 2022-03
• 期刊: Atmospheric Science Letters
• 影响因子: 3
• 作者: A. Raghavendra;G. Xia;Liming Zhou;Yan Jiang