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利用美国科罗拉多州立大学和MRC/ASTER发展的RAMS中尺度气象模式,以NECP再分析资料为初、边值条件,在兰州城区东面设计了有湖和无湖两个试验,做了72 h三重嵌套模拟试验,分别模拟了两种情况下冬季兰州山谷地区的湖泊效应和大气边界层特征。模拟结果表明:(1)白天兰州山谷地区谷风在14:00强度达到最大。加入湖泊后,14:00湖风强度增大,湖风对谷风没有明显影响,只对湖区及岸边附近的风场有影响。兰州山谷地区20:00以后山风开始出现,到05:00左右北山山风的风速大于南山山风。05:00以后南山山风风速增大,山谷以偏西风为主。加入湖泊后,陆风也在夜间02:00左右表现的最为明显,陆风和山风相互叠加,导致兰州山谷东部地区西风风速增大;(2)加入湖泊后,对周围地区气温的影响表现为夜间有增温作用,增温作用随着离湖泊的距离渐远而减弱。在靠近湖区处夜间的近地面逆温强度减弱;(3)加入湖泊后,对靠近湖面处空气相对湿度的影响表现为减小,对靠近湖西岸陆地上近地面空气相对湿度的影响表现为先减小后增加,这一点在夜间表现的最明显,对靠近湖面处空气绝对湿度的影响表现为增加;(4)加入湖泊后,湖区的净辐射和感热通量都减小,湖的东西两岸的净辐射和感热通量都增大。在22:00到凌晨05:00之间,靠近湖西岸的陆地上净辐射和感热通量也有所增大。
Based on the RAMS mesoscale meteorological model developed by Colorado State University and MRC / ASTER and using the NECP reanalysis data as initial and boundary conditions, two experiments were conducted in the east of Lanzhou City, Nested simulations were conducted to simulate the lake effect and the atmospheric boundary layer characteristics of the winter Lanzhou valley in winter and winter respectively. The simulation results show that: (1) The valley winds in Lanzhou Valley reach the maximum at 14:00 at daytime. After joining the lake, the intensity of the lake wind increased at 14:00 and the lake wind had no obvious effect on the valley wind, only affecting the lake area and the wind field near the shore. After 20:00 in Lanzhou Valley, mountain breeze began to appear, and the wind speed of Beishan mountain wind was greater than Nanshan mountain breeze around 05:00. After 05:00, the wind speed of Nanshan Mountain increased and the valley was mainly west wind. After entering the lake, the land breeze also showed the most obvious effect at about 02:00 at night. The combination of the land breeze and the mountain breeze resulted in the increase of the westerly wind speed in the eastern Lanzhou Valley. (2) After joining the lake, the impact on the ambient temperature was night There is a warming effect, warming effect with the distance away from the lake and weakened. The near-surface inversion temperature intensity at night near the lake area weakened; (3) The effect on the relative humidity of the air near the lake surface decreased when it was added to the lake, and the effect on the relative humidity of the near-surface air near the lake shore was first Decrease after the increase, which is most obvious at night, the impact on the absolute humidity of air near the lake showed an increase; (4) After joining the lakes, the net radiation and sensible heat flux in the lake are reduced, the lake things Both the net radiation and sensible heat flux have increased. Between 22:00 and 05:00, the net radiation and sensible heat flux on the land near the west bank of the lake also increased.