针对Local Analysis and Prediction System(LAPS)融合我国新一代多普勒雷达基数据时产生的资料空白问题,设计采用最大值和距离指数权重拼图方法来改进LAPS原有的最近邻居法,并且尝试通过最小二乘法来模拟静锥区的反射率值。试验结果表明,最大值法和距离指数权重法能够充分发挥多部雷达观测反射率的效能,有效地改善高仰角之间的资料空白现象,对静锥区也有一些的填补,特别是在对流层中层。最小二乘法拟合静锥区反射率试验取得了一定的效果,能够较好地拟合静锥区周围观测资料比较多的情况。该研究改善了LAPS同化国产多普勒雷达资料的能力,提高了多部雷达观测的利用效能,将会对LAPS分析产生积极的影响。
[Objective] The research aimed to analyze a rainstorm process in Chongqing. [Methed] Based on precipitation product datasets and NCEP reanalysis data, synoptic situation and diagnostic analysis of a heavy rain process during 11 -12 May, 2012 in Chongqing were made, and the diagnostic analysis included dynamic and vapor conditions, instability index, vapor helicity and vapor divergence flux. [ Result] The east-south moving short wave trough and east-north moving southwest vortex were the main synoptic systems causing the heavy rain; the positive vorticity advection before trough and after ridge helped the ascending motion from surface; the southwest stream at 700 hPa provided vapor and energy, promoting and maintaining the intense development of convection; the higher vapor helicity and lower vapor divergence flux were well corresponding with higher precipitation area, and had well temporal correlation, which was significant for forecast of precipitation area and its development; the ascended warm wet stream on the lower air came across the cold air on the upper air, triggering the heavy rain; the Kindex and A index were significant for the heavy rain forecasting. [ Conclusion] The research could provide some references for research and forecast of future rainstorm process in Sichuan and Chongqing.
基于区域气候模式RegCM4.0(Regional Climate Model 4.0),分别选取BATS(Biosphere Atmosphere Transfer Scheme)和CLM(Community Land Model)陆面方案,对2001—2005年中国的气候状况进行模拟,并将模拟结果与CRU(Climatic Research Unit)及GPCP(Global Precipitation Climatology Project)降水资料进行对比,研究不同陆面方案对降水模拟的影响。结果表明:在两种陆面方案下,区域气候模式均较合理地模拟出了中国降水的空间分布、时间变化;模拟降水对陆面方案敏感,RegCM_BATS总体上表现为正偏差,在东北区域的模拟偏差较大;RegCM_CLM表现为负偏差,在长江以南区域的模拟偏差较大;模拟结果的偏差在夏季较大,冬季较小;两模式模拟结果间的差异在空间上由东南向西北减少;两模式均较准确地模拟了不同强度降水出现频率的分布形势,总体上RegCM_CLM模拟低强度降水偏多;高强度降水偏少,而RegCM_BATS模拟低强度降水偏少,高强度降水偏多;不同陆面方案对地表蒸发量以及地表潜热通量模拟的差异是导致模拟降水差异的主要原因,夏季地表蒸发对降水的影响较冬季更强;水汽平流输送对两模式模拟降水差异的影响较小。
