区域气候模式在不同分辨率下对西北太平洋热带气旋生成气候特征的比较研究

利用RegCM3区域气候模式,试验研究了15、30、45和60 km 4个分辨率下西北太平洋热带气旋的生成特征.结果表明,RegCM3模式对西北太平洋热带气旋生成的模拟能力受分辨率的影响.分辨率的简单提高,并不一定会使模式的模拟能力有所改善.模式在30 km分辨率下对西北太平洋热带气旋生成频数及频数变化的模拟能力最强,在60 km分辨率下对西北太平洋热带气旋生成频数空间分布的模拟能力最强,在15 km分辨率下对西北太平洋热带气旋生成频数、频数空间分布及频数变化的模拟能力最弱.对比分析不同分辨率下热带气旋的生成过程表明,热带气旋生成前期,β中尺度涡旋没有发生合并,对流层中低层水汽含量不足是导致模式在15 km分辨率下模拟热带气旋生成频数较差的主要原因.

Comparison of Tropical Cyclogenesis Features over the Northwestern Pacific Simulated by Regional Climate Model with Different Resolutions

The tropical cyclogenesis features over the Northwestern Pacific simulated by Regional Climate Model Version 3.1 (RegCM3) with 15 km, 30 km, 45 km and 60 km resolutions are compared. It is found that the capability of RegCM3 on tropical cyclogenesis simulation over the Northwestern Pacific is influenced by resolution. The increase of resolution cannot always lead to the improvement of the simulation result. RegCM3 with 30 km resolution has the best capability of simulation on tropical cyclone (TC) genesis number and its variation. The capability of simulation by RegCM3 with 45 km resolution on TC genesis number and its variation is a little worse than RegCM3 with 30 km resolution. RegCM3 with 60 km resolution has the best capability of simulation on TC genesis position. RegCM3 with 15 km resolution has the worst capability of simulation on TC genesis number, TC genesis position and the variation of TC genesis number. The processes of TC genesis simulated by RegCM3 with different resolutions are compared. The results are as follows: The vortices cannot merger because of the small scale of them and the far distance between them. It may result in the decrease of TC genesis number in the simulation of RegCM3 with 15 km resolution. Much dry air involves in wet air before TC genesis and then reduces the water vapor and condensation latent heat release in the mid and lower troposphere. It may also result in the reduction of TC genesis number in the simulation of RegCM3 with 15 km resolution.