CAJ | 학술논문

利用常规观测、加密自动气象站降水资料以及NCEP/NCAR再分析资料等，使用天气动力学诊断方法，重点研究了高空急流对北京2012年7月21日（“7．21”）暴雨中降水突然增强时刻14时（北京时）和降水最强时刻19时的动力作用。结果表明，“7．21”暴雨的发生和西来的高空急流东移至北京上空有关，高空急流及其散度场和与高空急流相伴随的次级环流对“7．21”暴雨的发生起重要的动力作用。7月21日14时，高空急流轴的经向度开始增大，高空急流入口区右侧的散度场南北范围明显扩大，北京上空为深厚的对流运动，受来自低层的东南气流带来的暖湿空气的影响，北京地区降水量突然增大；20时，对流层高空急流轴的经向度进一步增大，此时由于北上西北低涡导致的低层辐合，使得北京上空对流层高层出现强辐散区，北京上空出现强烈的上升运动，加之来自东南的暖湿气流的影响，使得北京地区降水量在19时达到最大值。“7．21”暴雨中降水突然增强时刻和降水最大时刻，上升支均出现在高空急流入口区右侧，但是，次级环流的下沉支均发生在北京的东南部，这是影响“7．21”暴雨次级环流的一个重要特征。
이용상규관측、가밀자동기상참강수자료이급NCEP/NCAR재분석자료등，사용천기동역학진단방법，중점연구료고공급류대북경2012년7월21일（“7．21”）폭우중강수돌연증강시각14시（북경시）화강수최강시각19시적동력작용。결과표명，“7．21”폭우적발생화서래적고공급류동이지북경상공유관，고공급류급기산도장화여고공급류상반수적차급배류대“7．21”폭우적발생기중요적동력작용。7월21일14시，고공급류축적경향도개시증대，고공급류입구구우측적산도장남북범위명현확대，북경상공위심후적대류운동，수래자저층적동남기류대래적난습공기적영향，북경지구강수량돌연증대；20시，대류층고공급류축적경향도진일보증대，차시유우북상서북저와도치적저층복합，사득북경상공대류층고층출현강복산구，북경상공출현강렬적상승운동，가지래자동남적난습기류적영향，사득북경지구강수량재19시체도최대치。“7．21”폭우중강수돌연증강시각화강수최대시각，상승지균출현재고공급류입구구우측，단시，차급배류적하침지균발생재북경적동남부，저시영향“7．21”폭우차급배류적일개중요특정。
Based on the data from the conventional meteorological observation,including the surface hourly precipitation and the NCEP reanalysis data,using the weather diagnosis and analysis methods,the dynamic processes of the upper-level jet stream for the torrential rainfalls in Beijing,both increased suddenly at the time of 14:00 BT and of the biggest amount at 19:00 BT 21 July 2012 (named simply as 7.21 hereafter)are studied.The results show that the upper-level jet stream moved from the west to over Beijing is related to the Beijing 7.21 rainstorm,and the upper-level jet stream and its divergence field,and the seconda-ry circulation associated with the upper-level jet play an important role in the Beijing 7.21 rainstorm.At 14:00 BT 21,along with the upper-level jet stream northward spreading,the range of the upper-level divergence,which is situated at the right side of the entrance region of the upper level jet stream,expanded significantly.The Beijing region is under the influence of the deep convective motion and affected by the favorable moisture conditions,which was associated by the southeast flow,and thus caused the precipitation of the Beijing area to increase abruptly.At 20:00 BT 21,the upper-level jet stream further northward spreads,and the low-level convergence generated by the northwest vortex,resulted in the strong upper-level divergence over Beijing.The vertical motion enhanced by the strong upper-level divergence over Beijing,which combined with the impact of warm air from the south-east,leading the precipitation of Beijing region to reaching the maximum at 19:00 BT 21.The ascend-ing motions appeared in the right side of entrance region of the upper-level jet,while the descending motions occurred in the southeastern part of Beijing,at either the precipitation-increased suddenly time or the precipitation maximum time of Beijing 7.21 rainstorm.This is an important feature of the secondary circulation of the 7.21 Beijing rainstorm.