谱逼近方法在东亚夏季降水区域模式模拟中的适用性研究:区域大小和位置的影响

An application of the spectral nudging technique to the simulation of summer precipitation over East Asia using a regional climate model: The impact of domain size and position

中文关键词:  区域气候， 嵌套区域， 谱逼近， 夏季降水

英文关键词:RCM, Domain size, Spectral nudging, Summer precipitation

中文摘要:

      利用区域气候模式MM5V3对1991、1998和2003年的东亚夏季降水进行了模拟。首先通过6个嵌套区域大小、位置的敏感性试验，研究了区域气候模式在东亚地区的模拟对嵌套区域的敏感性。在此基础上研究了谱逼近方案对降低此敏感性的作用。结果表明：（1）区域气候模式MM5V3能够基本模拟出东亚夏季极端降水的分布特征和强度变化，模拟区域的选取对模拟结果有较大影响，随着嵌套区域的扩大，误差随之增大；此外，区域气候模式模拟的结果对于嵌套区域位置的选取也具有一定敏感性，主要表现在对侧边界附近的部分区域模拟存在一定偏差；（2）采用谱逼近方案后模式的模拟能力显著提高，整体上嵌套区域越大改进程度越明显。除改善了模式对大尺度环流场、雨带位置、强度及强降水中心的模拟外，谱逼近方法也能有效地降低试验间的个体偏差，即降低了区域气候模式在东亚地区对嵌套区域选择的敏感性。

英文摘要:

      The sensitivity of a regional climate model (RCM) in modeling summer precipitation over East Asia to domain choice is tested using the model PSU-NCAR MM5v3. The effect of interior (spectral) nudging is also assessed. The RCM simulations are evaluated against the NCEP/NCAR Reanalysis data. The results are: (1) the MM5 is able to simulate the distribution and magnitude of summer precipitation though with some biases. The biases increase with increasing domain area, and thus domain choice has a significant influence on model’s simulations. Moreover, the RCM simulations have some biases near the domain boundaries, and thus are sensitive to the position of domain. (2) By using interior (spectral) nudging, the performance of the MM5 shows large improvements that increase with increasing domain areas. Therefore, the RCM can reproduce more realistic large-scale circulations, seasonal mean precipitation fields and the intra-seasonal (daily) variability, and, the sensitivities of the RCM simulations to the choice model domain are reduced as well.