Realism of Rainfall in a Very High-Resolution Regional Climate Model
Realism of Rainfall in a Very High-Resolution Regional Climate Model
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DOI：
10.1175/jcli-d-11-00562.1
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发表时间：
2012-09-01
影响因子：
4.9
通讯作者：
Roberts, Malcolm J.
中科院分区：
文献类型：
--
作者：
Kendon, Elizabeth J.;Roberts, Nigel M.;Roberts, Malcolm J.
在气候模型中真实地反映当地的降雨量仍然是一个关键的挑战。真实性包括降雨的完整空间和时间结构，是模型在表现基本过程方面的关键指标。特别是，如果降雨量是更现实的气候模式，有更大的信心，在其预测的未来change.In这项研究中，现实主义的降雨量在一个非常高分辨率（1.5公里）的区域气候模式（RCM）相比，一个粗糙的分辨率12公里的RCM。这是第一次在联合王国的一个地区长时间（1989-2008年）运行允许对流的模型，从而可以从气候学意义上评估降雨的特征。特别是，在英国南部的每小时降雨的持续时间和空间范围进行检查，重点放在强降雨。降雨量在1.5公里的RCM被发现是更现实的比在12公里的RCM。在12公里的RCM中，暴雨事件的强度不够大，往往过于持久和广泛。虽然1.5公里的模式确实有暴雨过于强烈的趋势，但它仍然能更好地反映其持续时间和空间范围。气候模式中长期存在的问题，如持续小雨过多的趋势和日周期中的误差，在1.5公里的区域气候模型中也大大减少。在12公里的RCM的偏见似乎与对流的代表性的缺陷。
The realistic representation of rainfall on the local scale in climate models remains a key challenge. Realism encompasses the full spatial and temporal structure of rainfall, and is a key indicator of model skill in representing the underlying processes. In particular, if rainfall is more realistic in a climate model, there is greater confidence in its projections of future change.In this study, the realism of rainfall in a very high-resolution (1.5 km) regional climate model (RCM) is compared to a coarser-resolution 12-km RCM. This is the first time a convection-permitting model has been run for an extended period (1989-2008) over a region of the United Kingdom, allowing the characteristics of rainfall to be evaluated in a climatological sense. In particular, the duration and spatial extent of hourly rainfall across the southern United Kingdom is examined, with a key focus on heavy rainfall.Rainfall in the 1.5-km RCM is found to be much more realistic than in the 12-km RCM. In the 12-km RCM, heavy rain events are not heavy enough, and tend to be too persistent and widespread. While the 1.5-km model does have a tendency for heavy rain to be too intense, it still gives a much better representation of its duration and spatial extent. Long-standing problems in climate models, such as the tendency for too much persistent light rain and errors in the diurnal cycle, are also considerably reduced in the 1.5-km RCM. Biases in the 12-km RCM appear to be linked to deficiencies in the representation of convection.