京津冀平原区冬季大气环境容量变化:观测与预估

本文基于ERA5再分析数据,探究了京津冀地区冬季大气环境容量(Atmosphere Environmental Capacity,AEC)的时空变化特征以及相关影响因子。结果表明,冬季AEC在京津冀地区表现为西南部低,北部高的分布特征,其低值集中在平原区。京津冀平原区AEC变化与东亚冬季风、边界层高度、边界层内平均风速以及通风强度密切相关。东亚冬季风强、边界层高度高、边界层内平均风速大以及通风强度强,使得AEC偏高,反之亦然。进一步利用区域气候模式RegCM4对3个CMIP5全球气候模式的动力降尺度进行模拟,预估了京津冀平原区冬季AEC在RCP4.5和RCP8.5情景下的变化。结果显示,与1986—2005年相比,两种情景下京津冀平原区冬季AEC在21世纪中、末期都将下降,其中末期下降幅度高于中期、RCP8.5情景下的变化大于RCP4.5情景。上述变化与东亚冬季风减弱、东亚西风急流北移、边界层高度降低以及边界层内平均风速减小有关。

Changes of atmosphere environmental capacity in winter over the Beijing-Tianjin-Hebei Plain region: observation and projection

Based on ERA5 reanalysis data, the spatiotemporal variation characteristics and related influencing factors of Atmosphere Environmental Capacity (AEC) in winter over the Beijing-Tianjin-Hebei (BTH) region were explored. Results show that the winter AEC over the BTH region exhibits a distribution pattern of low in the southwest and high in the north, with low values concentrates in the plain areas. The changes of AEC over the BTH Plain are closely related to the East Asian winter monsoon, boundary layer height, average wind speed within the boundary layer, and ventilation intensity. The strong East Asian winter monsoon, high boundary layer height, high average wind speed within the boundary layer, and strong ventilation intensity result in higher AEC, and vice versa. Further more, the regional climate model RegCM4 was used to simulate the dynamic downscaling of three CMIP5 global climate models, and the changes in winter AEC over the BTH plain region under RCP4.5 and RCP8.5 scenarios were estimated. The projections indicate that compared with the period of 1986 to 2005, the winter AEC over the BTH plain region will decrease in both the middle and late 21st century under two scenarios, with a higher decrease in the late 21st century than the middle period and a greater change in the RCP8.5 scenario than in the RCP4.5 scenario. The above changes are related to the weakening of the East Asian winter monsoon, the northward movement of the East Asian westerly jet, the decrease in boundary layer height, and the decrease in average wind speed within the boundary layer.