我国东部夏季一次强对流活动过程中对流层上部大气成分变化的分析

利用星载微波临边遥感探测结果,对2006年6月28～29日江淮地区的一次强对流天气过程中对流层上部一氧化碳 (CO) 、臭氧 (O₃) 、水汽 (H₂O) 和冰水含量 (IWC) 的分布特点进行了研究.强对流天气过程前后的对比分析表明,CO混合比增大,在200 hPa处增加了0.12 ppm (1 ppm=10-6);O₃混合比减小,在70 hPa处减少了0.30 ppm;H₂O混合比在250 hPa处增加了400 ppm;IWC在强降水发生之前有大幅增长,在200 hPa处最大含量可达0.03 g/m3.CO和O₃含量与垂直运动速度两者的相关变化表明,对流垂直输送作用可能是造成对流层上层和平流层低层大气成分变化的机制之一.而H₂O和IWC含量的增加主要局限于对流层顶以下,这表明对流层上部水物质的质量和形态是由垂直输送作用和对流系统内部的微物理过程共同决定的.

Analysis of the Variation of Atmospheric Composition in the Upper Troposphere during a Strong Convection in Eastern China in Summer

The distribution of atmospheric composition, including carbon monoxide (CO), ozone (O₃), water vapor (H₂O), and ice water content (IWC), during a strong convective weather occurring in the Jianghuai areas is investigated based on measurements by the MLS (Microwave Limb Sounder) on the Aura satellite. Results show that the increase of CO mixing ratio at 200 hPa is 0.12 ppm, the decrease of O₃ mixing ratio at 70 hPa is about 0.30 ppm, and the increase of H₂O mixing ratio at 250 hPa is 400 ppm. The value of IWC has a sharp growth before the surface heavy rain occurs, and its maximum at 200 hPa is about 0.03 g/m³. The consistency variation between vertical velocity and mixing ratio of CO and O₃ indicates that the vertical transport is a conceivable mechanism changing the distribution of atmospheric composition in the upper troposphere and the lower stratosphere. Besides, H₂O mixing ratio and IWC also increase obviously when the convection is triggered, but the growth is limited below the tropopause. This suggests that not only the vertical transport but also the microphysical processes in the convection system decide the quality and phase of water in the upper troposphere.