Implications of Improved Representation of Convection for the East Africa Water Budget Using a Convection-Permitting Model
Implications of Improved Representation of Convection for the East Africa Water Budget Using a Convection-Permitting Model
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DOI：
10.1175/jcli-d-18-0387.1
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发表时间：
2019-03
影响因子：
4.9
通讯作者：
D. Finney;J. Marsham;L. Jackson;E. Kendon;D. Rowell;P. Boorman;R. Keane;R. Stratton;C. Senior
中科院分区：
文献类型：
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作者：
D. Finney;J. Marsham;L. Jackson;E. Kendon;D. Rowell;P. Boorman;R. Keane;R. Stratton;C. Senior
湿对流产生的降水和非绝热加热使其成为热带大气水分收支的重要组成部分。由于对流参数化是全球模式中已知的不确定性来源，允许对流模式（CP）越来越多地被用于改善对区域气候的理解。在这里，一个新的10年CP模拟用于研究东非和维多利亚湖流域的降雨和大气水收支的特点。对流的显式表示导致了广泛的改善，降雨的强度和日周期相比，参数化模拟。在大规模的水分通量的差异导致的平均降雨模式从刚果到维多利亚湖流域的CP模拟突出的对流和大规模的动态和降雨的代表性的地方变化之间的重要联系。CP模式中湖-陆浮力对比更强，导致维多利亚湖夜间陆风更强，蒸发和水汽通量辐合（MFC）增加，降雨量可能不切实际。然而，对于湖以东的山区，CP模式产生的日降雨量周期更类似于卫星估计，这是有关的MFC的时间差异。这里的结果表明，虽然需要照顾湖泊强迫，CP的方法提供了一个更现实的几个降雨特征，通过一个更物理为基础的实现周围的东非复杂地形的大气动力学的代表。
The precipitation and diabatic heating resulting from moist convection make it a key component of the atmospheric water budget in the tropics. With convective parameterization being a known source of uncertainty in global models, convection-permitting (CP) models are increasingly being used to improve understanding of regional climate. Here, a new 10-yr CP simulation is used to study the characteristics of rainfall and atmospheric water budget for East Africa and the Lake Victoria basin. The explicit representation of convection leads to a widespread improvement in the intensities and diurnal cycle of rainfall when compared with a parameterized simulation. Differences in large-scale moisture fluxes lead to a shift in the mean rainfall pattern from the Congo to Lake Victoria basin in the CP simulation—highlighting the important connection between local changes in the representation of convection and larger-scale dynamics and rainfall. Stronger lake–land contrasts in buoyancy in the CP model lead to a stronger nocturnal land breeze over Lake Victoria, increasing evaporation and moisture flux convergence (MFC), and likely unrealistically high rainfall. However, for the mountains east of the lake, the CP model produces a diurnal rainfall cycle much more similar to satellite estimates, which is related to differences in the timing of MFC. Results here demonstrate that, while care is needed regarding lake forcings, a CP approach offers a more realistic representation of several rainfall characteristics through a more physically based realization of the atmospheric dynamics around the complex topography of East Africa.