高分辨率MRI模式对青藏高原夏季降水及水汽输送通量的模拟

Simulation of Summer Precipitation and Associated Water Vapor Transport over the Tibetan Plateau by Meteorological Research Institute Model

本文使用MRI模式在不同分辨率下(180 km、120 km、60 km、20 km)的AMIP试验结果,分析了该模式对青藏高原夏季降水及水汽输送通量的模拟,并考察模式分辨率的影响。结果表明:MRI模式能够较为合理地模拟出青藏高原夏季气候平均的降水空间分布,但对气候平均水汽输送通量以及降水年际变化的模拟却存在较大的误差。随着分辨率的提高,该模式对青藏高原气候平均降水的模拟有明显改进,包括降水年循环以及夏季降水的空间分布等。分辨率为180 km、120 km、60 km、20 km的MRI模式模拟的青藏高原7月平均降水绝对误差分别为2.2 mm/d、1.2 mm/d、0.7 mm/d、0.2 mm/d。另外,高分辨率模式模拟的青藏高原夏季水汽输送通量的年际变化也更接近观测。当分辨率达到20 km时,MRI模式模拟的西风水汽输送指数与观测的相关系数达到0.43,通过了0.1显著性水平的显著性检验。但MRI模式对青藏高原夏季降水的年际变化以及气候平均水汽输送通量的模拟技巧并不随分辨率的增加有明显提高。低分辨率模式中模拟降水量偏大、印度季风槽偏强的现象在高分辨率模式中仍然存在。

Simulations of summer precipitation and associated water vapor transport over the Tibetan Plateau, as well as the impact of resolution, are analyzed with Atmospheric Model Intercomparison Project experiment results under various resolutions （i.e., 180, 120, 60, and 20 km） by using the Meteorological Research Institute （MRI） model. The model shows to reasonably reproduce the climate mean summer precipitation distribution over the Tibetan Plateau. However, the interannual variability of precipitation and water vapor transport failed to be captured by this model. With an increase in resolution, the simulation of climate mean summer precipitation improved significantly, including the annual cycle and spatial distribution. The simulation of interannual variability of the water vapor transport was much closer to the third generation reanalysis of the European Centre for Medium Range Weather Forecasts （ERA-interim）. However, little improvement in model skill was noted in the simulation of interannual variability of summer precipitation over the Tibetan Plateau and the climate mean water vapor transport. Thus, overestimation of summer precipitation amount and Indian trough remains in high-resolution models.