不同边界层参数化方案对东亚夏季风气候模拟的对比研究

用WRF v3.2.1中尺度预报模式和NCEP/NCAR再分析资料,对比研究了WRF模式中5个不同边界层参数化方案对东亚夏季风气候的模拟效果。结果表明:WRF模式对各边界层参数化方案均较为敏感,采用不同的边界层参数化方案对模拟区域内的夏季降水、气温、环流等气候要素均可产生明显影响。选取MYJ方案和QNSE方案对500 h Pa夏季平均环流的模拟效果较好,YSU方案和QNSE方案对夏季平均日降水量模拟与再分析资料更吻合,YSU方案和MYNN2.5方案对中国东部2 m气温的模拟结果较好。不同边界层参数化方案模拟结果都显示出由于副热带高压偏强,使副热带高压第2次北跳后停留时间过短,导致长江中下游降水偏少,华北地区降水增多。通过比较YSU和QNSE边界层方案,发现YSU方案相比QNSE方案的降水差异,是由于850 h Pa水汽输送造成的。在中国大部分地区YSU方案的2 m温度比QNSE方案高,并且地面2 m气温和降水存在一定对应关系。因此合理选取边界层参数化方案可以提高数值模拟的准确性。

Impact of different planetary boundary layer parameterizations on summer monsoonal climate simulation in East Asia

By using mesoscale WRF model version 3.2.1 and NCEP/NCAR reanalysis data, the simulation effects of five different planetary boundary layer parameterization schemes on summer monsoonal climate in East Asia are comparatively analyzed. The results show that WRF Model is sensitive to all the boundary layer parameterization schemes, each of which impacts greatly precipitation, temperature, circulation and other meteorological factors in simulation domain. In conclusion, the Mellor-Yamada-Janjic(MYJ) and Quasi-Normal Scale Elimination(QNSE) scheme simulated 500 hPa summer average circulation well. The results of summer average daily precipitation simulation by Yonsei University(YSU) and QNSE scheme are more close to the NCEP reanalysis dataset. YSU and Mellor-Yamada-Nakanishi-Niino, level 2.5(MYNN2.5) scheme both simulated 2 m temperature well in East China.Five planetary boundary layer parameterization schemes all overestimated the subtropical high, so that the subtropical high is unable to stay long enough to provide more precipitation in the middle and lower reaches of the Yangtze River, but it leads to more precipitation over North China. By comparison of YSU and QNSE schemes it was found that 850 hPa vapor transportation mainly caused the differentce of precipitation. In most regions of China, YSU simulated higher temperature at 2 m, furthermore, daily precipitation depends on the temperature at 2 m in most regions. Therefore, choosing a suitable planetary boundary layer parameterization scheme can improve the accuracy of numerical simulation results.