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黄建平, 何敏, 阎虹如, 等. 利用地基微波辐射计反演兰州地区液态云水路径和可降水量的初步研究[J]. 大气科学, 2010, 34(3): 548-558. DOI: 10.3878/j.issn.1006-9895.2010.03.08
引用本文: 黄建平, 何敏, 阎虹如, 等. 利用地基微波辐射计反演兰州地区液态云水路径和可降水量的初步研究[J]. 大气科学, 2010, 34(3): 548-558. DOI: 10.3878/j.issn.1006-9895.2010.03.08
HUANG Jianping, HE Min, YAN Hongru, et al. A Study of Liquid Water Path and Precipitable Water Vapor in Lanzhou Area Using Ground-Based Microwave Radiometer[J]. Chinese Journal of Atmospheric Sciences, 2010, 34(3): 548-558. DOI: 10.3878/j.issn.1006-9895.2010.03.08
Citation: HUANG Jianping, HE Min, YAN Hongru, et al. A Study of Liquid Water Path and Precipitable Water Vapor in Lanzhou Area Using Ground-Based Microwave Radiometer[J]. Chinese Journal of Atmospheric Sciences, 2010, 34(3): 548-558. DOI: 10.3878/j.issn.1006-9895.2010.03.08

利用地基微波辐射计反演兰州地区液态云水路径和可降水量的初步研究

A Study of Liquid Water Path and Precipitable Water Vapor in Lanzhou Area Using Ground-Based Microwave Radiometer

  • 摘要: 液态云水路径 (liquid water path, LWP) 和可降水量 (precipitable water vapor, PWV) 是描述天气和气候的两个重要物理量。目前, 针对液态云水路径和可降水量的直接观测较少, 特别是在我国干旱半干旱黄土高原地区, 至今没有获得系统的观测值。本文利用兰州大学半干旱气候与环境监测站 (SACOL) 近两年的微波辐射仪观测资料, 分析了黄土高原半干旱区液态云水路径和可降水量的变化特征。首先引入Liljegren et al.(2001) 的反演方法并加以改进, 计算得到适合黄土高原地区的反演参数, 利用改进后的反演方法计算近两年的液态云水路径和可降水量。分析结果显示, 与TP/WVP-3000型12通道微波辐射计的直接输出结果相比, 本文反演结果与实际情况更加吻合。在SACOL代表的黄土高原地区, 95%的云水路径值都在150 g/m2以下, 95%的可降水量值都在3 cm以下。由于SACOL的降水受亚洲季风的影响, 液态云水路径日均值冬季最小, 秋季最大, 其日变化规律显示半干旱区液态云水路径大体上呈双峰分布, 峰值主要出现在日出和日落时分。卫星反演资料的年变化趋势与地基反演结果比较吻合。因此, 运用卫星反演的液态云水路径来分析我国西北地区的空中云水资源是一种比较可信的手段。

     

    Abstract: Both liquid water path (LWP) and precipitable water vapor (PWV) are two important variables describing water source in the air, which are key elements in the energy budget and the workings of the hydrology. Currently, direct and continuous observations of LWP and PWV are few, especially for the Loess Plateau arid and semi-arid areas. The measurement of microwave radiometer at the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) is used to analyze the diurnal and annual variations of cloud liquid water path (LWP) in the semi-arid area. Firstly, Liljegren et al. retrieval method (Liljegren et al., 2001) is introduced and improved, and then used to calculate the retrieval coefficients suitable for the Loess Plateau, and LWP and PWV are computed using the modified retrieval method in the past two years. Compared with the artificial neural networks retrieval results of TP/WVP-3000, the improved Liljegren et al. retrieval results in this paper have smaller errors from the reality. The results show that 95% of LWP is below 150 g/m2, and 95% of PWV is below 3 cm at the SACOL. Because of the influence of Asian monsoon on precipitation, the daily average of LWP is the smallest in winter, the largest in autumn. The diurnal variation shows two peaks, which is due to local climate features, such as temperature inversion and thermal convection. Furthermore, the authors compare the annual variations of LWP derived from Terra and Aqua satellite with that from microwave radiometer, respectively. The results indicate that the satellite-derived results are close to the ground-based retrievals. Therefore, using LWP retrieved by satellites data to analyze the water source in the air over Northwest China is a relatively reliable method.

     

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