区域气候模式对不同的积云参数化方案在青藏高原地区气候模拟中的敏感性研究

Sensitivity of Regional Climate Model to Different Cumulus Parameterization Schemes in Simulation of the Tibetan Plateau Climate

本文使用MIROC3.2_hires模式输出资料作为RegCM3(The ICTP Regional Climate Model,V3.0)初边界资料,对RegCM3中常用的3种积云参数化方案Anthes-Kuo(AK)、Grell-Fritsch & Chappell(GFC)和MIT-Emanuel(MIT)方案在青藏高原地区的降水和气温模拟结果进行比较,检验了不同参数化方案在高原地区气候模拟的敏感性。结果表明,AK方案相对于GFC和MIT方案均较好地再现了气温和降水的时、空分布主要特征,就偏差大小而言,AK方案最接近观测,GFC方案次之,MIT相对较差,但3种方案模拟的温度均存在一个系统性的冷偏差。AK方案在空间分布特征和区域平均的年际变化特征上更接近于观测,但模拟的多年平均温度在高原大部分地区仍存在一个系统性冷偏差,尤其在高原主体冷的偏差约达4℃;而在塔里木盆地和准噶尔盆地则偏高约2℃;青藏高原南部冷偏差大于北部,年际变率较观测值略小。降水的模拟结果则表明,在高原主体部分较观测偏多0～6mm/d,高原北部降水模拟偏多而南部偏少,降水年际变率也略小于观测值。因此,就年、季、月尺度而言,积云参数化方案对中尺度区域气候模式的模拟结果产生的差异并不敏感。另外,RegCM3相对MICRO3.2_hires显著改进了GCM的模拟结果,尤其对地形复杂的天山、塔里木盆地、准噶尔盆地、昆仑山、冈底斯山脉和高原东南部地区的温度和降水细节上的刻画要明显好于GCM模拟结果,表明区域气候模式在青藏高原地区具有较好的降尺度作用。

To examine the sensitivity of cumulus parameterization scheme in climate simulating over the Tibetan Plateau, three cumulus parameterization schemes in RegCM3 （The ICTP Regional Climate Model, V3.0）, Anthes-Kuo （AK）, Grell-FritschChappell （GFC）, and MIT-Emanuel （MIT） are compared and analyzed in temperature and precipitation simulation over the Tibetan Plateau. The results show that AK, GFC and MIT schemes well reproduce the distribution of temperature and precipitation over the Tibetan Plateau, and the spatial distribution and annual change of the simulated temperature and precipitation with AK scheme are more closed to observations than other schemes. The simulated temperature shows that there is a systematic cold bias over the Tibetan Plateau about the three schemes. There is a cold bias about 4℃ over Tibet and a warm bias about 2℃ over Tarim and Junggar Basin, the cold bias over the south is large than the north over Tibet, and the variability of temperature is slightly smaller than the observed values. Precipitation simulation results indicate that the simulated precipitation is 0-6 mm/d more than observed one, the simulated one is high in the north and low in the south, the variability of precipitation is also slightly smaller than the observed values. In addition, RegCM3 distinctly improved the MICRO3.2 simulation results, the distribution details of temperature and precipitation are better than the MICRO3.2 simulations for complex terrains, such as Tianshan, Tarim Basin, Junggar Basin, Kunlun Mountain, Gangdise Mountain, and southeastern Tibetan Plateau, which implies that the RegCM3 performance is successful in downscaling.