Page 109 - 《高原气象》2021年第5期

高 原 气 象 40 卷
1070

Analysis of Radar Echo Characteristics of Short-term Heavy Precipitation

Weather with Different Circulation Pattern in East Gansu Province

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KONG Xiangwei ，YANG Jiancai ，LI Hong ，YANG Yi 1
（1. College of Atmospheric Sciences，Lanzhou University/Joint Center of Research and Training for Weather and
Climate Prediction，Lanzhou 730000，Gansu，China；
2. Lanzhou Central Meteorological observatory，Lanzhou 730020，Gansu，China；
3. Institute of Arid Meteorology，China Meteorology Administration，Lanzhou 730020，Gansu，China）

Abstract：In order to try to establish the connection between large-scale synoptic situation configuration patterns
and the medium and small scale radar characteristics，15 regional short-term heavy precipitation weather process‐
es from 2010 to 2015 in East Gansu Province are used. These short-term heavy precipitation synoptic situation
configuration patterns are divided into three patterns：eastward moving plateau low trough pattern，edge of sub‐
tropical high pattern，and northwest airflow pattern according to the difference of the main influence system in
the 500 hPa. The common characteristics of weather radar echo structure and its’evolution under different pat‐
terns are also analyzed. The results show that：（1）The radar echo of the eastward moving plateau low trough pat‐
tern is usually a mid-β-scale stratified mixed band echo of NNE-SSW trend，which is consistent with the trend
and position of the low-level jet axis on the right side of 700 hPa cold shear line. The band echo is mostly formed
in southeast Gansu，and the southerly low-level jet has an important influence on its propagation direction，
which makes it maintain for 3~4 hours，even 5~6 hours，often accompanied by "train effect". The radar echo cen‐
ter of mass is low，warm cloud precipitation is dominant，and with high precipitation efficiency.（2）The radar
echo edge of subtropical high pattern is usually a mid-β-scale narrow band echo of NE-SW direction located near
the ground front，which is slightly ahead of 700 hPa cold shear line. This kind of radar echo is usually generated
when the rapid moved cold air（cold front）intrudes into the central area of Gansu Province. When the cold front
moves to the southeast of Gansu Province，the radar echo gradually evolves into the characteristics that of east‐
ward moving plateau low trough pattern. However，its speed of moving southeast is faster than eastward moving
plateau low trough pattern.（3）The radar echo of northwest airflow pattern is relatively scattered and localized，
it is mainly a mid-γ-scale block echo. Either short life cycle convective cell generates and eliminates，or multi-
cell storm organizes，combinates and reinforces. The development of convective cell is more vigorous than the
former two patterns，belongs to deep convection.
Key words：Short-term heavy precipitation；synoptic situation configuration model；mesoscale convective sys‐
tem；Radar echo characteristics