基于卫星数据研究热带气旋眼壁及周围螺旋云带宏微观结构特征

ANALYZING ON THE CLOUD MICRO-AND MACRO-PHYSICAL PROPERTIES OF CYCLONE EYE WALL AND ITS SURROUNDING SPIRAL CLOUD BANDS BASED ON CLOUDSAT AND TRMM DATA

利用CloudSat卫星和TRMM卫星数据,对比分析2013年5个不同强度的热带气旋过程中气旋眼壁及周围螺旋云带的云宏微观结构特征、热力结构和降水特征。结果表明：发展成熟的气旋,冰相云主要分布在5km以上的高度。冰粒子有效半径随高度增加而减小,冰水含量随高度整体呈现先增长后减小的趋势,冰粒子数浓度随高度增加而增加。热力结构及降水方面,在眼区上空,除了一个众所周知的暖心区外,在眼区外部附近也可能出现一个暖区,高度约8-15km。降水率水平分布表现为大范围的层云降水中夹杂着独立的对流性降水,垂直降水一般从地面延伸到7.5km,其大值区主要集中在5km以下。在距离气旋中心较远的外围云系上层,也可能会有较多冰粒子存在,这主要是由于气旋眼壁云墙生成的冰粒子被带到外围对流云系后二次抬升所致。

In this study, the micro- and macro-physical properties, thermal structure and precipitation characteristics of cyclone eye wall and its surrounding spiral cloud were analyzed by CloudSat and TRMM data for five tropical cyclones in 2013. Results show that the ice-phase cloud in a matured typhoon is mainly above the 5 km height. The cloud droplet effective radius decreases, and particle number concentration increases, with increasing altitude. Ice water content first increases and then decreases with increasing height. In the eye area, in addition to the well-known warm-core area, another warm core also appeared around the eye at the height of 8 to 15 km. The horizontal distribution of precipitation was characterized by a large-scale stratiform precipitation, mixed with independent convective precipitation. The height of precipitation was mostly below the height of 7.5 km, and the heavy rain was mainly below 5 kin. When the peripheral convective clouds were strong enough, the ice particles would be generated out there, thus providing conditions favorable for the formation of the precipitation below.