Toward Eliminating the Double Inter-Tropical Convergence Zone and Improving El Nino/Southern Oscillation Simulation in the NCAR Community Climate System Model Version 3 (CCSM3)

这是一个继续项目，重点是缓解双重热带间辐合带(ITCZ)问题，并改进完全耦合的NCAR社区气候系统模式CCSM3中的厄尔尼诺和南方涛动(ENSO)的模拟。这些都是CCSM3中最基本的缺陷之一。所用的基本研究工具是CCSM3和改进的张-麦克法兰对流方案。我们将分析耦合模式积分和改进的对流方案，以检验ITCZ和ENSO模拟的改进。为了解对流与大尺度环流的相互作用，以及对流参数化在消除双重ITCZ中的作用，将用原始对流方案和改进的对流方案进行短期(=10年)数值试验。ENSO模拟将侧重于赤道区域外纬向风应力与改进的太平洋对流模拟有关的作用，以及增强的马登-朱利安涛动(MJO)变率在增加模拟的ENSO循环周期性方面的作用。(2)通过精心设计的数值试验，提高了对流参数化在双重ITCZ问题中的作用；(3)改进了ENSO周期性的模拟；(4)找出了改进的原因，特别是地面风应力的作用和CCSM3中增强的MJO模拟。这项工作的完成将为以下方面提供新的见解：(1)新的积云对流参数化将如何改善对ITCZ的模拟，以及(2)导致缓解CCSM3 Broader影响中最基本模式缺陷的过程：这项研究将导致改进的气候系统模式，该模式正被世界各地的气候研究界用于广泛的气候变化研究。它还为研究生提供学习经验和培训。

This is a continuation project with a focus on mitigating the double Inter-Tropical Convergence Zone (ITCZ) problem and to improve the simulation of El Nino and Southern Oscillation (ENSO) in the fully coupled NCAR Community Climate System Model, CCSM3. These are amongst the most fundamental deficiencies in CCSM3. The basic research tools used are the CCSM3 and the improved Zhang-McFarlane convection scheme. The coupled model integrations with improved convection scheme will be analyzed to examine the improvement of ITCZ and ENSO simulations. Short term (=10 years) numerical experiments with both the original and improved convection scheme will be conducted to understand the interaction between convection and the large-scale circulation, and the role of convection parameterization in the elimination of double ITCZ. The ENSO simulation will focus on the role of the zonal wind stress off the equatorial region in relation to the improved simulation of convection in the Pacific and the role of enhanced Madden-Julian Oscillation (MJO) variability in increasing the periodicity of the simulated ENSO cycle. Intellectual merit: The PI will (1) Improve the simulation of the ITCZ precipitation to eliminate the double ITCZ problem in CCSM3, (2) Improve scientific understanding of the role of convection parameterization in the double ITCZ problem through carefully designed numerical experiments, (3) Improve the simulation of ENSO periodicity, and (4) Find the causes of the improvements, in particular, the roles of surface wind stress and enhanced MJO simulation in the CCSM3. Completion of this work will offer new insights into: (1) Ways the new cumulus convection parameterization will result in an improved simulation of ITCZ, and (2) Processes that results in the mitigation of the most fundamental model deficiencies in CCSM3Broader impacts: The research will lead to an improved climate system model that is being used worldwide by the climate research communities for a wide spectrum of climate change research. It also provides learning experiences and training for a graduate student.