Fowler Laura D, Barth Mary C, Alapaty Kiran
National Center for Atmospheric Research, Boulder, Colorado 80307-3000, USA.
Center for Environmental Measurements and Modeling, U.S. Environmental Protection Agency Research Triangle Park, North Carolina 27711, USA.
Geosci Model Dev. 2020 Jun 29;13(6):2851-2877. doi: 10.5194/gmd-13-2851-2020.
The cloud liquid water path (LWP), ice water path (IWP), and precipitation simulated with uniform- and variable-resolution numerical experiments using the Model for Prediction Across Scales (MPAS) are compared against Clouds and the Earth's Radiant Energy System (CERES) and Tropical Rainfall Measuring Mission data. Our comparison between monthly-mean model diagnostics and satellite data focuses on the convective activity regions of the tropical Pacific Ocean, extending from the Tropical Eastern Pacific Basin where trade wind boundary layer clouds develop to the Western Pacific Warm Pool characterized by deep convective updrafts capped with extended upper-tropospheric ice clouds. Using the scale-aware Grell-Freitas (GF) and Multiscale Kain-Fritsch (MSKF) convection schemes in conjunction with the Thompson cloud microphysics, uniform-resolution experiments produce large biases between simulated and satellite-retrieved LWP, IWP, and precipitation. Differences in the treatment of shallow convection lead the LWP to be strongly overestimated when using GF, while being in relatively good agreement when using MSKF compared to CERES data. Over areas of deep convection, uniform- and variable-resolution experiments overestimate the IWP with both MSKF and GF, leading to strong biases in the top-of-the-atmosphere longwave and shortwave radiation relative to satellite-retrieved data. Mesh refinement over the Western Pacific Warm Pool does not lead to significant improvement in the LWP, IWP, and precipitation due to increased grid-scale condensation and upward vertical motions. Results underscore the importance of evaluating clouds, their optical properties, and the top-of-the-atmosphere radiation budget in addition to precipitation when performing mesh refinement global simulations.
利用跨尺度预测模型（MPAS）进行的均匀分辨率和可变分辨率数值实验所模拟的云液态水路径（LWP）、冰水路径（IWP）和降水，与云与地球辐射能量系统（CERES）以及热带降雨测量任务数据进行了比较。我们将月平均模型诊断结果与卫星数据之间的比较聚焦于热带太平洋的对流活动区域，该区域从贸易风边界层云发展的热带东太平洋盆地延伸至以深厚对流上升气流和延伸的对流层上层冰云为特征的西太平洋暖池。使用尺度感知的格雷尔 - 弗雷塔斯（GF）和多尺度凯恩 - 弗里茨（MSKF）对流方案，并结合汤普森云微物理，均匀分辨率实验在模拟的与卫星反演的LWP、IWP和降水之间产生了很大偏差。浅对流处理方式的差异导致在使用GF时LWP被严重高估，而与CERES数据相比，使用MSKF时两者相对吻合较好。在深对流区域，均匀分辨率和可变分辨率实验使用MSKF和GF时都高估了IWP，导致相对于卫星反演数据，大气顶长波和短波辐射存在很大偏差。西太平洋暖池区域的网格细化并未因网格尺度凝结和垂直上升运动增加而使LWP、IWP和降水得到显著改善。结果强调了在进行网格细化全球模拟时，除了降水外，评估云、其光学特性以及大气顶辐射收支的重要性。
