摘要
利用常规观测资料、加密自动站资料、NCEP 1°×1°再分析资料、FY-2E卫星、多普勒雷达以及中尺度数值模式资料,对2012年7月25—26日发生在天津的一次持续性、局地性大暴雨天气过程进行了初步分析。结果表明,大暴雨发生在稳定的经向环流背景之下,中高纬度为典型的两槽一脊形势,台风"维森特"减弱的低气压与副热带高压西侧的偏南风急流共同形成了向华北输送水汽和能量的重要通道,将孟加拉湾水汽源源不断输送到暴雨区;副热带高压边缘西南暖湿气流向北输送形成华北平原高温高湿天气,为大暴雨产生积累了不稳定能量,冷空气侵入加强了垂直运动发展,冷暖空气交汇触发本地能量释放,使得降水迅速加强。强降水由三个β中尺度对流云团发展加强所致,与β中尺度对流云团相对应的是若干个γ中尺度对流回波,明显的列车效应和充沛的水汽供应导致降水时间长、强度大。
Tentative analysis of a continuous local heavy rainfall event from July 25 to 26 in 2012 over Tianjin is performed with the conven- tional and automatic weather stations （AWS） observation data, NCEP 1° × 1° reanalysis data, FY-2E satellite imageries, Doppler radar da- ta and data from a mesoscale numerical model. The results show that this event occurs against the background of stable meridional circulation and typical ＂two troughs and one ridge＂ pattern in the mid-and high- latitudes. Vicente typhoon low in South China and southerly jet in the western part of subtropical high form a crucial water vapor and energy transfer to North China jointly, thus, abundant moisture from Bengal Bay is continuously transported to heavy rain areas in North China. The southwest warm and wet airflow at the edge of subtropical high is con- veyed northwards to form high temperature and high humidity environment over the North China Plain to accumulate unstable energy produc- ing the extra heavy rain. Meanwhile, the intrusion of cold air strengthens vertical upward motion, and the meet of cold and warm air triggers lo- cal energy release reinforcing precipitation quickly. The development and reinforcement of three β -mesoscale convective cloud clusters in coherence with several γ-mesoscale convective echoes resuh in the severe precipitation, and remarkable train effect and rich water vapor supply lead to high intensity and long lifetime of the rainstorm.
出处
《暴雨灾害》
2012年第3期226-231,共6页
Torrential Rain and Disasters
基金
公益性行业(气象)科研专项"华北
东北暴雨发生发展特点及预报技术研究"(GYHY200906011)
中国气象局预报员专项(CMAYBY2012-004)
关键词
大暴雨
副热带高压
低空急流
列车效应
extra heavy rain
subtropical high
low-level jet
train effect
