Evaluation of Evaporation Climatology for the Congo Basin Wet Seasons in 11 Global Climate Models
Evaluation of Evaporation Climatology for the Congo Basin Wet Seasons in 11 Global Climate Models
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DOI：
10.1029/2019jd030619
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发表时间：
2020-03
期刊：
影响因子：
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通讯作者：
D. Crowhurst;S. Dadson;R. Washington
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文献类型：
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作者：
D. Crowhurst;S. Dadson;R. Washington
在整个刚果，在耦合模式相互比较项目5全球气候模式（GCM）中，两个雨季的降雨量分布很广。由于刚果被认为是一个水分循环的热点，在一些模型中，多余的水分从陆地表面蒸发可能会放大模型在降雨中的传播。本研究在11个耦合模式相互比较项目中对刚果盆地的蒸发进行了基于探索性过程的评估，其中5个GCM参加了大气模式相互比较项目。我们的目标是提高对刚果蒸发的科学认识，并确定是否有机会改进模型如何产生刚果蒸发。从气候学的角度来看，我们发现，具有“真实”降雨量的模型模拟的11月（第二个雨季的高峰）的降雨量高于第一个雨季的高峰3月。然而，“真实”蒸发模型模拟的11月蒸发量低于3月，因为这些模型抑制了11月蒸发量的蒸腾成分。在两个雨季，次网格降雨方案使这些模式模拟一个可信的蒸腾比冠层蒸发，并导致他们在更现实的方式产生蒸发。因此，我们相信这些模型如何在潮湿的季节产生蒸发，并认为较低的蒸腾作用很可能解释为什么实际上11月的蒸发量低于3月。我们还建议，使用次网格降雨计划在所有的GCM可以改善如何生产刚果蒸发模型在雨季。这可能会减少模型在刚果降雨中的传播。
Across the Congo, there is a wide spread in rainfall in the two wet seasons in Coupled Model Intercomparison Project 5 global climate models (GCMs). As the Congo is believed to be a moisture recycling hot spot, the evaporation of excess water from the land surface in some models could be amplifying the model spread in rainfall. This study performs an exploratory process‐based evaluation of Congo Basin evaporation in 11 Coupled Model Intercomparison Project 5 GCMs that took part in the Atmospheric Model Intercomparison Project. Our aims are to improve scientific understanding about Congo evaporation, and to determine whether there are opportunities to improve how models produce Congo evaporation. Climatologically, we find that models with “realistic” rainfall simulate higher rainfall in November, the peak of the second wet season, than March, the peak of the first. However, models with “realistic” evaporation simulate lower evaporation in November than March, because these models suppress the transpiration component of the evaporation in November relative to March. In both wet seasons, subgrid rainfall schemes make these models simulate a credible ratio of transpiration to canopy evaporation, and cause them to generate evaporation in a more realistic manner. We therefore trust how these models produce evaporation in the wet seasons, and argue that lower transpiration is likely to explain why evaporation is lower in November than March in reality. We also suggest that using subgrid rainfall schemes in all GCMs could improve how models produce Congo evaporation during the wet seasons. This might reduce the model spread in Congo rainfall.