摘要
本文主要用修改的Nickerson等(1986)提出的中尺度模式,研究了在我国北方(49°19′N,119°55′E)草原开垦地所形成的行星边界层。其基本结果是:1)正午开垦地的“热岛”强度达4—6℃。下垫面的热力扰动可达700m高度,而对流扰动可达行星边界层顶,对流速度为1-2cm·s^(-1);2)一旦草原被大范围开垦,其边界层气候就会朝干热方向演变;3)灌溉可以减轻开垦地的“热岛”强度和旱情,但不能阻止气候的干热化过程,4)行星边界层内局地环流的方向在一昼夜内保持不变,即低层150—200m高度以下的气流由草原吹向开垦地,风速达2m·s^(-1)左右,上层为返回气流,速度略小于下层。草原上的湿气流在水平方向伸入开垦地可达30-50km。
PBL conditions over reclaimed grassland in northern China (49°19'N, 119°55'E) are examined using the improved mesoscale model originally proposed by Nickerson et al. (1986). Basic results are presented as follows:1) the reclaimed section or the 'heat island' has noon intencity of 4-6℃, the surface disturbance can be felt at 700 m AGL and convective perturbance at the PBL top, with the convective speed of 1-2 cm/s; ii) once grassland is reclaimed on a large scale, the PBL climate will divelop into further aridity; iii) irrigation can alleviate the intensity and dryness of the 'island' but fails to prevent the climate from aridization; iv) the local circulation in the PBL keeps its direction unchanged in 24 hrs, i.e., wind blows toward the 'island' at the height below 150-200 m at roughly of 2 m/s and returns at higher levels with a slightly smaller speed. Further, moist flow can extend 30-50 km horizonally inside the reclamation.
出处
《气象学报》
CSCD
北大核心
1992年第4期450-458,共9页
Acta Meteorologica Sinica
