CAJ | 학술논문

利用常规观测资料、地面加密自动站、多普勒雷达等多种观测资料以及雷达变分同化分析系统（VDRAS）的高分辨率分析场资料,对2012年7月21日发生在北京的全市性大暴雨、局地特大暴雨的系统结构演变特征及成因进行了初步分析。结果表明：（1）此次降水过程分为两个阶段,第一阶段在21日10—20时,呈现出短时雨强大且波动性显著的对流性降水特点,第二阶段降水在21日20时—22日04时,降水相对平缓,表现为锋面降水特征。（2）21日天气尺度环流形势场配置满足华北暴雨的典型背景条件：高空急流形成的辐散与对流层中低层的低涡、切变线及地面倒槽构成的深厚辐合区,形成强烈垂直运动并持续维持的机制,造成了长达16 h的强降水过程;副热带高压外围的东南水汽通道和西南低空急流的水汽输送为暴雨发生提供了充沛水汽条件。（3）大暴雨过程第一阶段降水回波具有明显的＂列车效应＂传播特征＂,列车效应＂的初始对流起源于地形强迫造成的暖区内中尺度辐合以及低空急流增强过程中的风速脉动;中尺度对流单体沿低空急流轴左侧传播,具有明显的重力波传播特征,西南急流的稳定维持使惯性重力波不断从背景场中获得能量并不断发展。（4）地形对降水有明显的增幅作用,边界层内长时间维持的东南风在太行山脉前与西南风和东北风交汇,在山前形成辐合带并长时间维持,有利于水汽积聚;山脉的阻挡使东南气流在迎风坡爬坡抬升,从而加大了山前区域的降水量。
이용상규관측자료、지면가밀자동참、다보륵뢰체등다충관측자료이급뢰체변분동화분석계통（VDRAS）적고분변솔분석장자료,대2012년7월21일발생재북경적전시성대폭우、국지특대폭우적계통결구연변특정급성인진행료초보분석。결과표명：（1）차차강수과정분위량개계단,제일계단재21일10—20시,정현출단시우강대차파동성현저적대류성강수특점,제이계단강수재21일20시—22일04시,강수상대평완,표현위봉면강수특정。（2）21일천기척도배류형세장배치만족화북폭우적전형배경조건：고공급류형성적복산여대류층중저층적저와、절변선급지면도조구성적심후복합구,형성강렬수직운동병지속유지적궤제,조성료장체16 h적강강수과정;부열대고압외위적동남수기통도화서남저공급류적수기수송위폭우발생제공료충패수기조건。（3）대폭우과정제일계단강수회파구유명현적＂열차효응＂전파특정＂,열차효응＂적초시대류기원우지형강박조성적난구내중척도복합이급저공급류증강과정중적풍속맥동;중척도대류단체연저공급류축좌측전파,구유명현적중력파전파특정,서남급류적은정유지사관성중력파불단종배경장중획득능량병불단발전。（4）지형대강수유명현적증폭작용,변계층내장시간유지적동남풍재태행산맥전여서남풍화동북풍교회,재산전형성복합대병장시간유지,유리우수기적취;산맥적조당사동남기류재영풍파파파태승,종이가대료산전구역적강수량。
The synoptic configuration features and contributing factors of a torrential rain occurring in Beijing region on 21 July 2012 have been preliminarily investigated by using conventional observation data, intensive automatic weather station observations, Doppler-Radar data etc. and low-level thermal and dynamical retrieval system of 4Dvar based on Variational Doppler Radar Analysis System (VDRAS). The con- clusions are drawn as follows. (1) There are two stages during the torrential rain. The first one is from 10 a.m. to 20 p.m. (LTC) on 21 July 2012 and presents convective precipitation with short-time, high rainfall intensity and obvious fluctuation. The second one is from 20 p.m. on 21 July to 04 a.m. on 22 July 2012 and presents smooth frontal precipitation. (2) The synoptic scale circulation situations on 21 July are typical circulation pattern of North China heavy rain. The divergence caused by high-level jet, low-vortex and shear in the lower and middle tropo- sphere, and deep convergence zone triggered by surface inverted trough cause the formation and continuance of strong vertical upward motion, which lead to 16 h severe precipitation process. The southeast moisture channel at the periphery of subtropical high and the southwesterly low-level jet supply sufficient moisture condition for the occurrence of torrential rain. (3) The precipitation echoes in the first stage of the pro- cess have an obvious train effect whose initiate convection originates from both mesoscale convergences in warm regions caused by topograph- ic forcing effect and wind velocity fluctuation in the enhancing process of low-level jet. The mesoscale convective cells moving along the left side of low-level jet axle have a significant gravity wave transmitting feature. The stable continuance of southwesterly jet made inertia-gravitational wave ohtain energy from amhient field and develop continuously. (4) Topography promotes precipitation increment. The southeast wind in boundary layer joins southwest wind or northeast wind in front of the Taihang Mountain and forms a continuing eonvergenee zone in front of lhe mountains, which is in rawer of the accumnlation of vapor, meanwhile, the southeast airflow is uplifted at the windward slope of lhe mountains, whieh leads to the increase of precipitation in the regions in front of the mountains.