青藏高原夏季边界层再分析资料的偏差分析及订正

Deviation analysis of reanalysis data in boundary layer in summer over Tibetan Plateau and its simulation correction

青藏高原对流边界层的热力、动力过程对下游地区甚至整个东亚地区的天气气候有重要影响。以2017年夏季为例分析ERA-Interim、JRA-55和MERRA-2再分析数据在青藏高原边界层研究中的适用性,并进一步利用数值模式物理框架的约束作用来订正其分析误差。2017年夏季青藏高原东南部边界层内,3套再分析资料对于气象要素的描述能力为气温>露点温度>水平风场,研究时段内适用性较好的再分析资料为ERA-Interim。比较12种模式参数化方案组合,模拟结果对于再分析资料在晴空和中雨情景下水平风场的误差离散程度均有明显改善。对于模拟改进的关键物理量水平风场而言,研究时段内本地适用性最高的参数化方案组合是ACM2+WSM6+BMJ。再分析资料中的风场经模拟结果调整后可以更好地描述青藏高原夏季边界层发展,证实模式参数化方案可以减小其在高原地区季节分布偏差。

The thermal and dynamic processes of the convective boundary layer over the Tibetan Plateau(TP) have an important impact on weather and climate of the downstream region and even the entire East Asia region. This paper uses a summer case of 2017 as an example to analyze the applicability of three sets of reanalysis data including ERA-Interim, JRA-55 and MERRA-2 in the study of the boundary layer over the TP, and further uses the constraints of the numerical model physical framework to correct its analysis error. In the summer of 2017, the variation of air temperature and dew point temperature were presented well through the three sets of reanalysis data in the boundary layer over the southeastern TP, while the reproducibility of the horizontal wind field was very poor, and the reanalysis data with better applicability over the TP during the study period was ERA-Interim. The results from the 12 parameterization scheme combinations selected in this paper were compared by the dispersion degree of the horizontal wind field error, improvements of the simulations in clear skies and moderate rain were significant. Therefore, for the simulated critical physical quantity(the horizontal wind field), the combination of Betts-Miller-Janjic, WSM6 and ACM2 scheme was the most locally applicable in the study area. The wind field in the reanalysis data could describe the summer boundary layer development over the TP more closely after adjustment using simulation results. It was proved that the model parameterization scheme could reduce its deviation of seasonal distribution in the plateau area, which had certain guiding significance for subsequent research and application.