Convection Parameterization and Climate Simulation in the National Center for Atmospheric Research (NCAR) Community Climate System Model

NCAR社区气候系统模式(CCSM)中的两个缺陷被认为与模式中对流的参数化有关。因此，与观测值相比，该模型偏向于热带大气中较弱的季节内变率和阿拉伯半岛的过度降水。由于CCSM的广泛使用，进行研究以解决这些问题非常重要。本研究项目的目标是通过模式中的对流参数化来解决这些问题。具体地说，这项研究旨在实现以下基本科学目标：(I)了解不同气候条件下对流与大尺度过程的相互作用；(Ii)纳入观测数据以改进CCSM中的对流参数化；(Iii)改进CCSM中对流和大气状态的模拟时间变异性；(Iv)确定CCSM中阿拉伯半岛降水模拟错误的原因并消除它。这项工作使用的基本研究工具是CCSM的大气成分NCAR CCM3和张麦克法兰对流方案，以及来自热带和中纬度不同对流机制的现场观测数据。将使用统计和合成技术对改进对流参数化的模拟进行分析，以检查热带季节内变率的改善。系统的初始趋势误差分析将被应用于一系列精心设计的数值试验的模拟中，以了解CCM3中阿拉伯半岛夏季降水偏大的原因。这项研究应能改进对流参数化，更好地理解对流的作用，并在NCAR CCM3中更好地模拟热带气候及其变异性。这项研究之所以重要，是因为它具有改进气候预测和预测的潜力，这些预测和预测对世界社会具有重大价值。

Two deficiencies in the NCAR Community Climate System Model (CCSM) are believed to be related to the parameterization of convection in the model. The model is thus biased toward weak intraseasonal variability in the tropical atmosphere and excessive precipitation in the Arabian Peninsula, compared to observations. Because of the wide use of the CCSM, it is important to conduct research to address them. The goal of this research project is to address these issues by focusing on convective parameterization in the model. Specifically, the investigation aims to achieve the following fundamental scientific objectives: (i) Understand how convection interacts with the large-scale processes in different climate regimes; (ii) Incorporate observational data to improve convective parameterization in CCSM; (iii) Improve the simulated temporal variability of convection and the atmospheric state in CCSM; (iv) Determine the cause of the erroneous precipitation simulation over the Arabian Peninsula in CCSM and eliminate it.The basic research tools used in this work are the NCAR CCM3, which is the atmospheric component of CCSM, and the Zhang-McFarlane convection scheme, together with field observational data from different convection regimes in the tropics and midlatitudes. Simulations with improved convective parameterization will be analyzed using statistical and composite techniques to examine the improvement in the tropical intraseasonal variability. Systematic initial tendency error analysis will be applied to simulations from a series of carefully designed numerical experiments to understand the causes of large summer precipitation bias in the Arabian Peninsula in CCM3. The research should result in an improved convective parameterization, a better understanding of the role of convection and a better simulation in tropical climate and its variability in the NCAR CCM3. This research is important because it has potential to improve climate predictions and projections, which are of great value to world societies.