The Diurnal Cycle and Its Depiction in the Community Climate System Model

作者：Aiguo Dai, Kevin E. Trenberth · 发表于：Journal of Climate · 年份：2004 · DOI：10.1175/1520-0442(2004)017<0930:tdcaid>2.0.co;2 · 被引用次数：509 · 研究领域：Climate variability and models、Meteorological Phenomena and Simulations、Atmospheric Ozone and Climate

To evaluate the performance of version 2 of the Community Climate System Model (CCSM2) in simulating the diurnal cycle and to diagnose the deficiencies in underlying model physics, 10 years of 3-hourly data from a CCSM2 control run are analyzed for global and large-scale features of diurnal variations in surface air temperature, surface pressure, upper-air winds, cloud amount, and precipitation.The model-simulated diurnal variations are compared with available observations, most of which were derived from 3-hourly synoptic reports and some new results are reported for surface air temperatures.The CCSM2 reproduces most of the large-scale tidal variations in surface pressure and upper-air winds, although it overestimates the diurnal pressure tide by 20%-50% over low-latitude land and underestimates it over most oceans, the Rockies, and other midlatitude land areas.The CCSM2 captures the diurnal amplitude (1Њ-6ЊC) and phase [peak at 1400-1600 local solar time (LST)] of surface air temperature over land, but over ocean the amplitude is too small (Յ0.2ЊC).The CCSM2 overestimates the mean total cloud amount by 10%-20% of the sky from ϳ15ЊS to 15ЊN during both December-January-February (DJF) and June-July-August (JJA) and over northern mid-and high-latitude land areas in DJF, whereas it underestimates the cloud amount by 10%-30% in the subtropics and parts of the midlatitudes.Over the marine stratocumulus regions west to the continents, the diagnostic cloud scheme in the CCSM2 under...