台风外围环流对沿海地区大气边界层结构的影响研究

Influence of Typhoon Peripheral Circulation on Atmospheric Boundary Layer Structure in Coastal Areas

结合茂名外场观测数据以及气象要素再分析数据,对台风外围环流影响和局地海陆风环流(SLBC)影响下沿海地区的大气边界层(ABL)结构识别方法和特征规律展开研究。利用气象要素探空数据和微脉冲激光雷达(MPL)观测数据进行了大气边界层高度(BLH)识别方法的适用性分析,提出了一种新的基于微脉冲激光雷达的BLH识别方法,以有效提高复杂边界层结构情况下激光雷达识别BLH结果的准确性,进而分析了受大尺度和局地环流影响的ABL结构以及BLH的时空变化特征。结果表明:沿海地区在没有大尺度天气系统的控制时,局地SLBC的影响较为显著,会使ABL出现多层复杂结构,BLH表现出波峰和波谷交替出现的日变化规律;BLH开始增长的时间一般出现在白天的陆风-海风转换时刻,最大值一般出现在正午气溶胶层顶的位置,即2 km左右;BLH下降的时间通常伴随着夜间的海风-陆风转换,最小值一般出现在夜间残留层以下稳定边界层顶的位置,低至500 m左右。而台风外围环流控制下,局地SLBC引起的局地对流现象会被抑制,ABL昼夜交替的空气上升、下沉运动减弱甚至消失,整个ABL内气溶胶垂直分布较为均匀,BLH与气溶胶层顶基本重合,维持在2 km左右,BLH变化波动不大且没有比较明显的日变化规律。

In this paper, we investigate the identification methods and characteristics of the atmospheric boundary layer structure(ABL) in coastal areas under the influence of typhoon peripheral circulation and local sea-land breeze circulation(SLBC) based on the field observation data and the reanalysis data of meteorological elements in Maoming. We use the meteorological element sounding data and the micro-pulse lidar(MPL) observation data to analyze the applicability of the retrieving method of the atmospheric boundary layer height(BLH). Then, we propose a new MPL-based BLH recognition method, which can greatly improve the BLH results with the complex boundary layer structure. Furthermore, we analyze the ABL structure and the characteristics of the temporal and spatial changes in the atmospheric BLH under the influence of large-scale and local SLBC. In coastal areas, the influence of local SLBC is more significant without the control of large-scale weather systems and thus the ABL will have a multi-layered complex structure. In addition, the BLH shows the daily variation of wave crests and troughs. Generally, BLH starts to grow at the time of land-sea breeze transition in the daytime, and the maximum is generally about 2 km at the top of the aerosol layer at noon. Then, BLH decline is usually accompanied by the sea-land breeze transition at night, and the minimum generally appears at the stable boundary layer top below the residual layer, as low as about 500 m. Under the control of typhoon peripheral circulation, the local convection caused by the local SLBC will be suppressed. The air rising and sinking of the ABL alternation will weaken or even disappear. The vertical distribution of aerosols in the ABL is relatively uniform, and BLH and aerosol top basically coincide at about 2 km. The BLH changes little, without obvious diurnal variation.