黄丹青,钱永甫. 2008. 坡地坡向短波辐射参数化对不同天气过程的影响[J]. 气象学报, 66(1):90-100, doi:10.11676/qxxb2008.009
坡地坡向短波辐射参数化对不同天气过程的影响
The effects of the slope irradiance on different weather processesunder different model resolutions.
投稿时间:2006-04-18  修订日期:2007-03-15
DOI:10.11676/qxxb2008.009
中文关键词:  GRAPES,坡地坡向短波辐射,天气过程
英文关键词:Nonhydrostatic mesoscale model, GRAPES, Slope irradiance, Slope and orientation of topography, Weather processes.
基金项目:中国气象科学研究院十五攻关项目“中国气象数值预报技术创新研究”(2001BA607B续)、“国家重点基础研究发展计划”(973)项目:“我国南方致洪暴雨监测与预 测的理论和方法研究” (2004CB418300)和国家自然科学基金重点项目“江淮梅雨的年际和年代际变化规律及其机制研究”(40233037)
作者单位
黄丹青 南京大学大气科学系、南京大学灾害性天气气候研究所南京 210093 
钱永甫 南京大学大气科学系、南京大学灾害性天气气候研究所南京 210093 
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中文摘要:
      为了改进太阳短波辐射参数化,运用考虑了坡地坡向短波辐射效应(SLOPE)的非静力中尺度模式GRAPES(全球/区域同化和预报系统),模拟和讨论了坡地坡向短波辐射效应在不同模式分辨率情况下对中国不同天气过程的影响。数值试验表明:(1)当水平分辨率较低且坡地平缓时,通常可忽略坡地辐射效应,但当水平分辨率较高且地形陡峭起伏时,则不能忽略;(2)在高分辨率(3 或6 km格距,下同)的情况下, 降水的增加和减少与坡地坡向引起的地表短波辐射(GSW)的减少和增加相对应,降水量的增减量大部分均为-5—5 mm;(3)在高分辨率的情况下,地表温度与地表热通量之间有较好的相关性,且大都发生在地形复杂的多山地区;(4)坡地坡向短波辐射效应引起的GSW、降水量、地表温度和地表热通量等要素的变化除了在地形复杂的多山地区比较明显之外,在其他地区也存在。这是由于考虑了坡度和坡向的作用后,影响了大气环流的变化,随着积分时间的增加,其他地区上述物理量也相应地存在一定的变化;(5)坡地坡向对短波辐射的作用,在降水量较小,云量较少的天气过程中,可以更真实地得到反映。因此,在地形复杂和水平分辨率较高情况下,需要考虑坡度坡向作用。
英文摘要:
      Solar radiation is obviously an important surface forcing factor. Currently short wave radiation scheme in GRAPES ( Global/ Regional Assimilation and Prediction System) is based on Dudhia (1989) and taken from MM5. It is a simple downward integration of solar flux, accounting for clear-air scattering (Lacis and Hansen 1974), water vapor absorption , cloud albedo and absorption, and uses look-up tables for clouds from Stephens (1978). Short wave radiation at the ground surface (GSW) is originally calculated under the assumption of horizontal surface. This method of estimating the GSW may lead to considerable errors when the model resolution becomes high and the model terrain steep. To improve solar short wave radiation parameterization, slope irradiance has been implemented into nonhydrostatic mesoscale model GRAPES as it has been used in many climate models for its good performance. In this paper, the effects of the slope irradiance on different short range weather processes in China under different model resolutions are simulated and discussed. In the simulation, topography heights are taken from NCEP with a resolution of 1 km, and the slope and orientation of terrain calculated by using the staggered difference schemes. The results show that when the model resolution is low and the slope of terrain is small, then the influence of slope and orientation of terrain on the GSW is negligible, otherwise, it is not negligible. Under the circumstance of the high resolution (3 and 6 km, hereafter the same), the increase or decrease of simulated precipitation are respectively corresponding to the decrease and increase of the GSW induced by the slope effect, the increments of precipitation are usually ranged between 5 and –5 mm. And furthermore, the surface temperature and heat fluxes are close correlated each other, mostly in the complex terrain mountainous regions. The changes in GSW, precipitation, surface temperatures and heat fluxes induced by the effects of terrain irradiance are obvious in mountainous regions, besides, some minor changes are also found in other remote areas due to the circulation alternations. It is also found that in the weather condition with less cloudiness and less precipitation, the effects of slope irradiance can be more realistically shown. Therefore, slope irradiance can normally be neglected in numerical models when the horizontal model resolution is low and the slopes are moderate, and should be included when the resolution becomes high and the terrain steep and rugged
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