Using qflux to constrain modeled Congo Basin rainfall in the CMIP5 ensemble
Using qflux to constrain modeled Congo Basin rainfall in the CMIP5 ensemble
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DOI：
10.1002/2016jd025596
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发表时间：
2016-11
期刊：
影响因子：
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通讯作者：
A. Creese;R. Washington
中科院分区：
文献类型：
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作者：
A. Creese;R. Washington
耦合模型是我们诊断和预测未来气候的工具，但在某些地区，它们被严重低估。刚果盆地就是这样一个地区，由于观测数据严重缺乏，科学界对它的关注有限。全球气候耦合模式在流域降水气候学上存在很大差异。本研究试图解决这一研究差距，通过评估模拟降雨量和分布之间的全球耦合模型耦合模式相互比较项目5（CMIP5）合奏。在某些月份，模型之间的平均月降雨量变化高达5倍，并且模型在最大降雨量的位置上不一致。集合平均值通常被认为是耦合模式输出的“最佳估计”，与任何单一模式都不一致，因此不太可能呈现可能的降雨状态。水汽通量（qflux）的收敛（这是假设是更好地约束比参数化降雨）被发现有很强的关系与降雨，最强的相关性发生在700 hPa的3月至5月（r = 0.70）和850 hPa的6月至8月，9月至11月，12月至2月（r = 0.66，r = 0.71，和r = 0.81）。在没有观测的情况下，这种关系可以用来限制模拟降雨的广泛范围，并更好地了解刚果降雨气候学。水分传输路径的分析表明，模拟降雨量是敏感的水分进入盆地。因此，在关键的刚果盆地边界进行有针对性的观测活动可能有助于限制模型降雨量。
Coupled models are the tools by which we diagnose and project future climate, yet in certain regions they are critically underevaluated. The Congo Basin is one such region which has received limited scientific attention, due to the severe scarcity of observational data. There is a large difference in the climatology of rainfall in global coupled climate models over the basin. This study attempts to address this research gap by evaluating modeled rainfall magnitude and distribution amongst global coupled models in the Coupled Model Intercomparison Project 5 (CMIP5) ensemble. Mean monthly rainfall between models varies by up to a factor of 5 in some months, and models disagree on the location of maximum rainfall. The ensemble mean, which is usually considered a “best estimate” of coupled model output, does not agree with any single model, and as such is unlikely to present a possible rainfall state. Moisture flux (qflux) convergence (which is assumed to be better constrained than parameterized rainfall) is found to have a strong relationship with rainfall; strongest correlations occur at 700 hPa in March–May (r = 0.70) and 850 hPa in June–August, September–November, and December–February (r = 0.66, r = 0.71, and r = 0.81). In the absence of observations, this relationship could be used to constrain the wide spectrum of modeled rainfall and give a better understanding of Congo rainfall climatology. Analysis of moisture transport pathways indicates that modeled rainfall is sensitive to the amount of moisture entering the basin. A targeted observation campaign at key Congo Basin boundaries could therefore help to constrain model rainfall.