Optimal configuration and resolution for the first convection-permitting ensemble of climate projections over the United Kingdom
Optimal configuration and resolution for the first convection-permitting ensemble of climate projections over the United Kingdom
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英国第一个允许对流气候预测集合的最佳配置和分辨率
DOI：
10.1002/joc.6415
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Fosser G
中科院分区：
文献类型：
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作者：
Fosser G
允许对流模式（CPM）在气候和天气预报时间尺度上提供了亚日降水统计和对流过程的更好表示。这项研究的目的是建立什么水平分辨率和物理过程设置是适合的对流允许的气候预测的第一个集合为英国。为此，使用三种不同的对流允许分辨率（网格间距为4 km，2.2 km和1.5 km）进行了长达12年的模拟，每种分辨率都有几种配置。重点是表示次日降水量的能力，因为它可能通过洪水对社会产生重大影响。分析表明，在对流允许范围内使用更细的网格间距可以改善亚日降水的表示，但随着网格变得越来越细，附加值会降低，同时计算成本会大幅增加。物理过程表示的变化可以产生与网格间距一样大的影响，并且可以导致对流参数化模式和CPM之间类似的日循环差异。虽然4公里模型显示出一些关键的缺陷，使其不可靠的气候预测，2.2公里模型表现以及1.5公里模型的大多数指标检查相当大的好处，在计算机成本方面。这里确定的最佳配置和分辨率正在用于英国气候预测2018（UKCP18）项目内运行的模拟集合，该项目首次允许在对流允许的尺度上估计未来变化的不确定性，并在当地和小时尺度上提供更可靠的气候变化预测。
Convection‐permitting models (CPMs) provide a better representation of sub‐daily precipitation statistics and convective processes on both climate and weather forecasting timescales. This study aims to establish what horizontal resolution and physical process settings are suitable for the first ensemble of convection‐permitting climate projections for the United Kingdom. For this purpose, 12‐year‐long simulations were run using three different convection‐permitting resolutions (grid spacing of 4 km, 2.2 km and 1.5 km) each with several configurations. The focus is on the ability to represent sub‐daily precipitation due to its potential for high impacts on society through flooding. The analysis shows that the use of a finer grid spacing within the convection‐permitting regime improves the representation of sub‐daily precipitation but the added value decreases as the grid becomes increasingly finer, while the computational costs substantially increase. Changes in the representation of physical processes can have as much impact as the grid spacing and can lead to similar differences in the diurnal cycle as between convection‐parametrized models and CPMs. Although the 4km model shows some key deficiencies that make it unreliable for climate projection, the 2.2km model performs as well as the 1.5km model for most of the metrics examined with considerable benefits in terms of computer cost. The optimal configuration and resolution identified here is being used for an ensemble of simulations run within the UK Climate Projections 2018 (UKCP18) project, which allows, for the first time, an estimate of uncertainty in future changes at convection‐permitting scale and providing more reliable climate change projections at local and hourly scales.