| 不同下垫面大孔径闪烁仪观测数据处理与分析 |
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| 引用本文： | 卢俐,刘绍民,徐自为,王介民,李小文.不同下垫面大孔径闪烁仪观测数据处理与分析[J].应用气象学报,2009,20(2):171-178. |
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| 作者姓名： | 卢俐 刘绍民 徐自为 王介民 李小文 |
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| 作者单位： | 1.北京师范大学遥感科学国家重点实验室, 地理学与遥感科学学院, 北京 100875 |
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| 基金项目： | 公益性行业(气象)科研专项基金，国家自然科学基金，国家高技术研究发展计划(863计划)，国家重点基础研究发展规划(973计划) |
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| 摘 要： | 大孔径闪烁仪是近年兴起的测量大尺度（500 m~10 km）地表通量的仪器。北京师范大学等单位分别于2002年、2004年在北京昌平小汤山开展了大孔径闪烁仪短期观测实验, 2006年6月又在北京密云建立了长期观测站。利用这些数据, 对大孔径闪烁仪观测数据进行处理与分析, 结果表明:闪烁仪光径高度和风速是影响观测显热通量的关键因子。当地表粗糙元的高度变化相对于光径高度不可忽略时, 零平面位移需要精确确定。波文比在湿润地表需要准确确定, 而气温、气压和动力学粗糙度则为不敏感因子。计算中所需的大气稳定度可用理查孙数判断, 也可借助日出日落时间或净辐射观测值确定。稳定条件下的普适函数目前无统一表达式, 可采用仪器说明书推荐的函数。通过几个站点闪烁仪观测显热通量与涡动相关仪测量值的比较表明:大孔径闪烁仪在均匀和非均匀地表都能得到合理的显热通量观测值。
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| 关 键 词： | 大孔径闪烁仪 显热通量 不同下垫面 |
| 收稿时间： | 6/3/2008 12:00:00 AM |
| 修稿时间： | 2/5/2009 12:00:00 AM |
Results from Measurements of Large Aperture Scintillometer over Different Surfaces |
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| Lu Li,Liu Shaomin,Xu Ziwei,Wang Jiemin and Li Xiaowen.Results from Measurements of Large Aperture Scintillometer over Different Surfaces[J].Quarterly Journal of Applied Meteorology,2009,20(2):171-178. |
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| Authors: | Lu Li Liu Shaomin Xu Ziwei Wang Jiemin and Li Xiaowen |
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| Institution: | 1.State Key Laboratory of Remote Sensing Science, School of Geography, Beijing Normal University, Beijing 1008752.Meteorological Information Center of Beijng, Beijng Meteorological Bureau, Beijing 1000893.Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000 |
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| Abstract: | For surface flux measurements, large aperture scintillometer (LAS) has become more and more popular in recent years. Compared with traditional observation techniques, it can measure surface fluxes on a larger scale (500 m-10 km). At present, LAS observation is not common in China. Beijing Normal University, associated with other institutes, has carried out several short term measurements of LAS at Xiao tangshan (Beijing, 2002, 2004). A long-term LAS site has also been constructed at Miyun (Beijing) in June, 2006. Sensible heat flux (H) calculation with the LAS data of above measurements shows that the beam height of LAS and wind speed are sensitive factors for sensible heat flux measurement (HLAs), zeroplane displacement height is crucial unless the beam height is much lager than it, and Bowen ratio needs to be determined accurately over wet surface, while air temperature, air pressure and aerodynamic roughness length are not sensitive for HLAs. There are two key points of HLAS calculation under stable condition. First, there is much less agreement on the form which universal stability function fT should take. In this study, the fT function proposed by Andreas (as in the LAS manual) is used. Further more, since the iteration process of HLAS can not be convergence when low wind speed and very stable conditions appearing at night, ψm≥-5 is specified. Second, the scintillometer is unable to determine the sign of the heat flux. Richardson Number Ri can be used to determine atmospheric stability and fix the sign of HLAS. Besides, the sunrise-sunset time and net radiation could be used for this purpose if there is no wind and air temperature profiles. Therefore, a calculation scheme of 24-hour sensible heat flux observed by LAS is obtained after settling the above two key points. According to the observations mentioned above, LAS can measure surface fluxes both over homogeneous and heterogeneous surfaces. The daily and monthly variation of HLAs is analyzed. And the observation differences between eddy covariance system and LAS, need to be studied further combined with footprint model and energy unbalance of eddy covariance system observation. |
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| Keywords: | large aperture scintillometer sensible heat flux different surfaces |
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