摘要:本研究在对华南季风降水试验（SCMREX）观测资料分析的基础上，采用数值模拟试验探讨南海北部区域湿度场初值误差和海上对流对2014年5月8日华南沿海地区的一次强降雨过程的中尺度对流系统（MCS）的发展和移动的影响。加密探空和风廓线观测分析表明在珠江口地区有西南风和偏东风急流形成的辐合区，为对流在该地区增强发展提供了条件。增加和减少近海湿度以及关闭积云和微物理过程潜热释放，所造成的温度场以及风场的变化对广东沿海地区的对流的强度和移动路径都有明显的影响。特别是增加海上关键区的湿度，由于海上对流的发展改变了整个区域的环流，抑制了陆地上对流的发展。关闭海上关键区对流过程潜热的释放，导致低空急流到达更加偏北的位置，对流系统在模拟的后期向东北移动。通过这些试验表明，海上的湿度等要素场和对流活动对沿海地区的降雨预报有着十分重要的影响，需要进一步加强海上观测及其资料同化方法。
关键词:中尺度对流系统/
低空急流/
敏感试验/
对流潜热/
降雨预报
Abstract:This paper utilizes observation data from the SCMREX (Southern China Monsoon Rainfall Experiment) and numerical sensitive simulation experiments to investigate the influence of moisture amount and convection development over the northern South China Sea on MCS (Mesoscale Convective System) of a heavy rainfall event in coastal South China on May 8, 2014.Intensive soundings and wind profiler data reveal that there existed a convergence region formed by the southwesterly and easterly jet in the Pearl River delta, which provided a favorable condition for the development of convection.When the initial relative humidity was increased or decreased in the offshore area, or latent heat released from the cumulus and microphysical processes were turned off, significant effects could be found on the intensity and movement of convection in the coastal area of Guangdong owing to the adjustment of temperature and wind fields.In particular, when increasing offshore initial humidity, prosperous sea convection modified the circulation in the entire simulation area, and suppressed the development of convection over the land.Moreover, if latent heat from cumulus and microphysical processes were turned off, the low-level jet could reach further north, and the convective system moved to the northeast in the later stage.These experiments indicate that the offshore initial moisture field and convection are indeed important for precipitation forecast in the coastal area.Therefore it is necessary to enhance offshore observation and data assimilation method in the future.
Key words:Mesoscale Convective System (MCS)/
Low-level jets/
Sensitivity experiment/
Latent heat/
Rainfall forecast
PDF全文下载地址:
http://www.iapjournals.ac.cn/dqkx/article/exportPdf?id=20180101
