双羽对流参数化方案在CIESM模式中的应用及对模拟气候的影响

Implementation of a double plume convection parameterization in the CIESM model and its impact on the modeled climate

  • 摘要: 将双羽对流参数化方案(以下简称双羽对流方案)应用到公共联合地球系统模式(CIESM)中,并研究了该方案对CIESM全耦合模拟气候特征的影响。通过国际耦合模式比较计划(CMIP-PiControl)21年积分,分析了双羽对流方案和CIESM原深对流、浅对流方案在模拟云和降水过程中的异同及敏感性来源。双羽对流方案耦合到CIESM模式中能得到基本合理的气候统计特征,较原模式减少了低纬度海洋区域的大气顶辐射通量负偏差。双羽对流方案增强了长波云辐射强迫,缓解了CIESM在低纬度区域的负偏差,但其在海洋性大陆和赤道印度洋存在高估。使用双羽对流方案的降水分布和赤道辐合带季节变化与原CIESM模式相似。CIESM模式很好地再现了北半球冬季Madden-Julian Oscillation(MJO)的东传信号,但MJO降水强度较观测偏弱。双羽对流方案提高了MJO降水强度。本研究验证了双羽对流方案在CIESM模式中可以稳定运行且气候特征合理,其在能量收支方面有待与其他物理过程进一步协同调试。

     

    Abstract: A double plume convection parameterization is implemented in the Community Integrated Earth System Model (CIESM). The impact of the double plume convection scheme on the modeled climate is studied based on the 21-year CMIP (PiControl) simulation. The modeled climate using the double plume convection scheme is evaluated by comparing with that using the default deep and shallow convection schemes. Using the double plume scheme overall can generate realistic climate statistics. The scheme reduces the negative biases in model top net radiation fluxes in the low-latitude oceanic regions. Longwave cloud forcing (LWCF) is increased by the double plume convection scheme. The negative biases in LWCF in the low latitudes are reduced, while positive biases arise over the Maritime Continent and the tropical Indian Ocean. Annual mean precipitation and seasonal variation of the Intertropical Convergence Zone is not sensitive to changes in convection parameterization. CIESM shows high skills in capturing the eastward propagation of Madden-Julian Oscillation (MJO), and the double plume convection scheme improves the variation of MJO precipitation. This study exhibits the stability and reasonableness of the double plume convection scheme for the CISEM coupled simulation. Collaborative parameter tuning is needed to further improve the energy budget for the double plume convection scheme.

     

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