Projection of global warming onto regional precipitation over Mongolia using a regional climate model
Projection of global warming onto regional precipitation over Mongolia using a regional climate model
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DOI：
10.1016/j.jhydrol.2006.07.023
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发表时间：
2007-01-30
影响因子：
6.4
通讯作者：
Kitoh, Akio
中科院分区：
文献类型：
--
作者：
Sato, Tomonori;Kimura, Fujio;Kitoh, Akio
全球变暖引起的气候变化是公众关注的问题，可能会导致干旱/半干旱地区水文状况的重大变化，包括蒙古，蒙古位于干旱和湿润地区之间的边界。然而，大气环流模式不足以评估区域尺度的气候变化。利用区域气候模式（RCM），采用两种动力降尺度方法（DDS），即G方法和R方法，对全球变暖引起的蒙古7月降水变化进行了研究。方法-G是传统的DDS方法，其中一个RCM直接嵌套在一个GCM中，而方法-R是本研究中新提出的，旨在提高区域气候的再现性。对于当前的气候模拟，方法R使用再分析数据作为RCM的边界强迫，而专业创建的边界条件，其中GCM模拟中的气象变量的预测变化被添加到再分析数据中，用于全球变暖模拟。与实地观测结果相比，即使在蒙古国四个分区的小范围内，RCM也能很好地再现7月份的降水量。方法R的降雨强度与实际观测结果非常接近;另一方面，方法G未能模拟强于16 mm日（-1）的暴雨事件。两种DDS方法对全球变暖导致的蒙古国7月降水量变化的结果相似，即蒙古国北方降水量减少，蒙古国南部降水量增加。在R方法中，强于4 mm日的中到强降水强度的降水减少对蒙古北方7月降水减少有很大贡献。由于降水量减少和气温上升导致潜在蒸发量增加的综合影响，7月份蒙古国的土壤湿度也呈下降趋势。这种情况表明，由于全球变暖的影响，严重干旱可能会更频繁地发生。(c)2006 Elsevier B. V.保留所有权利。
Climate change due to global warming is of concern to the public and may cause significant changes in the hydrological regimes in arid/semi-arid areas including Mongolia, which locates at a boundary between and and humid regions. However, general circulation models (GCMs) are not sufficient to evaluate climate change on a regional-scale. In this study, two kinds of dynamical downscaling (DDS), referred to as method-G and method-R, using a regional climate model (RCM) are applied to investigate the rainfall change over Mongolia in July due to the global warming. Method-G is a traditional DDS method in which an RCM is directly nested within a GCM, while method-R is newly suggested in this study and aims to improve the reproductivity of a regional climate. For current climate simulation, method-R uses reanalysis data as a boundary forcing of the RCM while a specialty created boundary condition, in which projected changes of meteorological variables in a GCM simulation are added on reanalysis data, is used for global warming simulation. Compared with in situ observations, the rainfall amount for July is very well reproduced by the RCM, even in a smatter area of four subregions in Mongolia. Rainfall intensity by method-R is very close to actual observations; on the other hand, method-G fails to simulate heavy rainfall events stronger than 16 mm day(-1). The two DDS methods show similar results with respect to the changes of precipitation in July due to the global warming, which are that precipitation decreases over northern and increases over southern Mongolia. In method-R, a decrease of precipitation of middle to heavy rainfall intensity, stronger than 4 mm day', contributes largely to the decreased July precipitation in northern Mongolia. Soil moisture over Mongolia also tends to decrease in July because of the combined effect caused by the decrease of precipitation and the increase of potential evaporation due to rising air temperature. This situation indicates that severe droughts may occur more frequently from the effects of global warming. (c) 2006 Elsevier B.V. All rights reserved.