An Evaluation of Arctic Cloud and Radiation Processes Simulated by the Limited-Area Version of the Global Multiscale Environmental Model (GEM-LAM)

作者：Simjanovski Dragan; Girard Eric^*; Du Ping

来源：Atmosphere-Ocean, 2011, 49(3): 219-234.

DOI：10.1080/07055900.2011.604266

• Arctic clouds
• cloud radiative effect
• cloud-radiation modelling
• regional climate model

Cloud and radiation processes simulated by the limited area version of the Global Environmental Multiscale Model (GEM-LAM) are evaluated for the period September 1997 to October 1998 over the western Arctic Ocean. This period coincides with the Surface Heat Budget of the Arctic Ocean (SHEBA) field experiment. Surface downwelling solar and terrestrial radiation, surface albedo, vertically integrated water vapour, liquid water path, precipitation, cloud cover and cloud radiative forcing simulated by GEM-LAM are evaluated against the SHEBA observation dataset. GEM-LAM simulates the annual cycle of the downwelling shortwave (SWD) and longwave (LWD) radiation at the surface reasonably well, as well as precipitable water at monthly and daily time scales. Cloud fraction at daily and monthly time scales is not captured well by the model. During winter, GEM-LAM produces a large negative bias for the vertically integrated liquid water path and a positive bias for cloud fraction. As a result, cloud radiative forcing at the surface and LWD radiation are well reproduced but for the wrong reasons because these two biases have an opposing effect on their magnitudes. During summer, the model underestimates the surface albedo, thus resulting in a substantial overestimation of the cloud radiative forcing at the surface. Precipitation is underestimated during winter and overestimated during summer and spring. The sensitivity of the results to the effective radius of ice crystals and the parameterization of cloud phase is also discussed.

• 出版日期2011-9-1