Investigation of Precipitation, Circulation, and Cloud Variability Over the Past Two Decades

To better understand the variability of precipitation, circulation, and cloud variables, we explore the precipitation, vertical velocity, total cloud fraction, condensed water path, and ice water path from 13 Coupled Model Intercomparison Project 5 (CMIP5) models over the past two decades. All variables are averaged over wet areas (precipitation > 200 mm/mon) and dry areas (precipitation <50 mm/mon) to investigate temporal variations of different variables over wet and dry regions. All models demonstrate similar temporal variations of precipitation as that from GPCP precipitation, with positive trends of precipitation over wet areas and negative trends of precipitation over dry areas. Positive trends of vertical velocity, total cloud fractions, condensed water path, and ice water path are also found from all models over the wet areas. Most of the models simulate decreasing trends of vertical velocity, total clouds, condensed water path, ice water path over the dry areas with a few exceptions. In summary, CMIP5 models simulate precipitation, vertical velocity, and cloud variability over wet areas and dry areas reasonably well. Results obtained from this study can help us better understand the variabilities of precipitation, vertical velocity, cloud, liquid and ice water contents over wet areas and dry areas, which are important for a better understanding of the atmosphere hydrological cycle.