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1.
三维辐射传输模式分析非均匀云对天空辐射场影响 总被引:3,自引:1,他引:3
为了解非均匀分立云体分布状况下的天空辐射场与无云晴空辐射场的差异, 本文借助一个三维辐射传输数值模式SHDOM模拟了离散云块分布条件下的天空辐射场分布, 重点分析不同云况分布情况下“非云”大气的辐射分布特征, 并将该区域与无云晴空大气辐射场的相同区域进行了比对。工作主要从辐亮度以及450 nm/650 nm的辐射比两参数入手进行讨论。研究发现, 相对无云晴空大气, 云的存在会对周围“非云”大气散射辐射产生影响, 影响程度与云量、云及气溶胶光学厚度等参数相关。数值模拟结果表明, 在云量不太大的条件下, 无云视场空间的大部分辐射值与无云晴空相比变化很小, 集中在±2%之间。这一结果表明, 已有的一维均匀大气辐射传输模式运算结果所得云与非云相元的判据基本适用于非均匀分布的有云大气。另一方面, 模拟结果表明我们也完全可以利用非均匀有云大气中的无云视场观测结果进行大气气溶胶等晴空大气光学特征的探测研究。 相似文献
2.
Junhua YANG Zhenming JI Deliang CHEN Shichang KANG Congshen FU Keqin DUAN Miaogen SHEN 《大气科学进展》2018,35(6):628-644
The application of satellite radiance assimilation can improve the simulation of precipitation by numerical weather prediction models. However, substantial quantities of satellite data, especially those derived from low-level(surface-sensitive)channels, are rejected for use because of the difficulty in realistically modeling land surface emissivity and energy budgets.Here, we used an improved land use and leaf area index(LAI) dataset in the WRF-3 DVAR assimilation system to explore the benefit of using improved quality of land surface information to improve rainfall simulation for the Shule River Basin in the northeastern Tibetan Plateau as a case study. The results for July 2013 show that, for low-level channels(e.g., channel 3),the underestimation of brightness temperature in the original simulation was largely removed by more realistic land surface information. In addition, more satellite data could be utilized in the assimilation because the realistic land use and LAI data allowed more satellite radiance data to pass the deviation test and get used by the assimilation, which resulted in improved initial driving fields and better simulation in terms of temperature, relative humidity, vertical convection, and cumulative precipitation. 相似文献
3.
Ultraviolet (UV) solar radiation has a significant influence on human health, the environment and climate. A series of measurements, including UV radiation (290 400 nm) and global solar radiation (Rs), were continuously recorded from August 2004 at the Lhasa and Haibei sites on the Tibetan Plateau. Both observation sites' altitudes are above 3000 m and have similar meteorological conditions. The data from 2005 2006 was used to identify the varying characteristics of UV radiation. It's relation to the clearness index Ks, the relative optical mass mr, and Rs were established. The annual mean values of total daily UV radiation are 0.92 and 0.67 MJ m^-2 at Lhasa and Haibei, respectively. The UV radiation in Lhasa represented 4.6% of the global solar radiation while in Haibei this percentage was 4.2%. In the case of clear days (Ks 〉 0.8), these percentages ranged between 4.0% and 4.5% in Lhasa and between 5.1% and 5.5% in Haibei. In the case of cloudy days (Ks 〈 0.4), these percentages ranged from 4.4% to 6.8% in Lhasa and from 5.1% to 5.5% in Haibei. The maximum values of UV radiation for each relative optical mass diminished exponentially with mr. Thus, for Lhasa and Haibei, UV=46.25mr-129, and UV=51.76mr-142, respectively. The results of this study can be used to obtain more UV radiation data for the study of UV climate characteristics, the effects of UV on ecological processes and the feedback of the thinning of the stratospheric ozone, from more routine measurements Rs data. 相似文献