| MODIS反照率产品在模拟黄河源区陆面过程和降水中的应用 |
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| 引用本文： | 史小康,文军,田辉,等.MODIS反照率产品在模拟黄河源区陆面过程和降水中的应用[J].大气科学,2009,33(6):1187-1200. |
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| 作者姓名： | 史小康 文军 田辉 等 |
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| 作者单位： | 中国科学院寒区旱区环境与工程研究所西部气候与环境灾害实验室, 兰州,730000 |
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| 基金项目： | 国家自然科学基金基金项目:40775022;财政部/科技部公益类行业专项GYHY200706005 |
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| 摘 要： | 地表反照率是陆面过程中一个重要的物理量, 其变化直接影响地表能量的收支状况, 进而可以影响气温和降水等其它气象要素。本文利用WRF (Weather Research and Forecasting) 模式, 通过两组数值模拟试验分别探讨了地表反照率改变在黄河源区不同下垫面情况下潜热、 感热的分配关系, 详细分析了地表反照率改变对降水变化的影响机制, 最后应用EOS/MODIS地表反照率产品替代原模式低时空分辨率的地表反照率。研究结果表明: (1)当地表反照率减少(增加)时, 模拟的区域平均地表温度、感热、潜热数值相应增大(减少)。当地表反照率减少0.1时, 地表温度上升约1.0 K, 感热和潜热量增量比约为3∶1。 (2) 地表反照率改变对降水量变化影响最大的区域是黄河源区下游的草场区域, 其次是黄河源头区域, 最小的是黄河源区北部的稀疏植被区域。地表反照率通过对大气动力、 热力以及水汽条件的影响, 使得降水发生的环境改变, 主要体现在: 当地表反照率减少时, 地表气压的减少使得大气低层的辐合气流增强, 有利于上升运动的发生; 2.0 m气温的升高增强了大气近地层的热力不稳定度; 2.0 m比湿的增加表明近地层空气水汽含量增加。 (3) 与实况对比分析发现, 使用卫星遥感产品后在月尺度上能够更准确地模拟降水量的变化过程。
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| 关 键 词： | 地表反照率 黄河源区 WRF模式 卫星遥感资料同化 降水 |
Application of MODIS Albedo Data in the Simulation of Land Surface and Rainfall Processes over the Yellow River Water Source Region |
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| SHI Xiaokang,WEN Jun,TIAN Hui and et al.Application of MODIS Albedo Data in the Simulation of Land Surface and Rainfall Processes over the Yellow River Water Source Region[J].Chinese Journal of Atmospheric Sciences,2009,33(6):1187-1200. |
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| Authors: | SHI Xiaokang WEN Jun TIAN Hui and |
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| Institution: | Laboratory for Climate Environment and Disasters of Western China, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou,730000 |
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| Abstract: | Land surface albedo (LSA) is a very important geophysical variable in the land surface process. The change of LSA has a direct impact on the surface energy balance, and then can make air temperature and precipitati-on change by land-atmosphere interaction. To investigate the influence of LSA changes under different surface con-ditions over the Yellow River water source region, two sets of numerical simulation experiments are conducted by using the WRF (Weather Research and Forecasting) model. Firstly, the impact of LSA changes on the distribution of latent heat and sensible heat is discussed, and then the mechanism of precipitation changes is also explored in de-tail. At last, the original LSA with low spatial and temporal resolution in this model is substituted by the EOS/MO-DIS LSA product for improving the simulation ability of the model The results indicate that: (1) When LSA de-creases (or increases), the simulated sensible heat and latent heat increase (or decrease). When LSA decreases 0. 1, the ratio of sensible to latent heat increments is approximate to 3:1. (2) It has the biggest impact on the amount of precipitation in the downriver grassland of the Yellow River water source region and has the smallest impact in the region north of the Yellow River water source region where the land cover is mainly sparse vegetation. The mecha-nism that the change of LSA leads to the change of precipitation, taking the decrease of LSA as an example, is em-bodied in three aspects. First, the decrease of surface air pressure induced by the decrease of LSA increases the low-level atmospheric convergent flow, and then enhances the upward movement of air. Second, the increase of 2. 0-m temperature accelerates the thermal instability in the low-level atmosphere. Third, the increase in 2. 0-m specific hu-midity indicates more water vapor content in the near-surface layer. (3) Compared with observed monthly rainfall, the assimilation experiment which uses the EOS/MODIS LSA product could improve the accuracy of precipitation simulation. |
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| Keywords: | land surface albedo the Yellow River water source region WRF model satellite remote sensing data assimilation precipitation |
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