大孔径闪烁仪观测数据的处理方法研究

大孔径闪烁仪可以获取公里级尺度的显热/潜热通量,其观测数据在农林业、水文、气象等领域的研究中具有越来越重要的作用.以海河流域2008年密云站和馆陶站大孔径闪烁仪的观测数据为例,讨论了数据筛选与处理方法,以及大气不稳定状态下不同处理方法对显热通量造成的影响.结果表明:空气折射指数结构参数应结合电压信号的方差进行计算、采用逐日的日平均波文比系数进行湿度订正、结合空间权重函数计算有效高度、选取Andreas(1988)稳定度函数计算显热通量等是可信的.通过对不同插补方法的比较可知,采用非线性回归方法和以零值替代的方法对不稳定状态和稳定状态下30 min缺失的显热通量进行插补,采用动态线性回归方法对日显热通量的缺失进行插补是可行的.为了解决由于冬天净辐射和显热通量较小,造成能量平衡方程余项法计算的蒸散量产生较大误差的问题,可采用根据大孔径闪烁仪与涡动相关仪观测的日蒸散量建立的关系式进行估算.基于上述方法的研究,形成了一套较为完整的大孔径闪烁仪观测数据的处理流程,保证了在不同下垫面、不同的天气状况条件下都能获取质量可靠、数据连续的大孔径闪烁仪观测的显热/潜热通量.

A Study of the Processing Method of Large Aperture Scintillometer Observation Data

Sensible/latent heat fluxes can be obtained by Large Aperture Scintillometer (LAS) over several kilometers, which play an significant role in the analysis of and application to agricultural and forestry, hydrology and meteorology research. Take LAS observations in Miyun and Guantao stations over Hai River Basin in 2008 as an example. The way of data screening and quality control under unstable conditionsas well as the effect of different calculation method on sensible heat flux have been discussed. The results showed: the structure parameter of the refractive index (C²_n) should be calculated with the variance of the voltage of structure parameter of the refractive index; Humidity correction can be done with daily Bowen ratio; The effective height of LAS can be calculated with spatial averaged function; The Andreas(1988) function is used to get reliable sensible heat flux. Meanwhile, the nonlinear regression method and dynamic linear regression method have been used to fill the 30min and daily missing data while the 30 min missing data under stable conditions can be set to zero. The correlation relationship between daily ET measured by LAS and EC has been constructed to estimate daily ET when daily R_n<50 W/m². Based on the above analysis, a set of LAS data processing scheme has been set up, which ensures continuous and high quality sensible/latent data can be obtained over various surfaces and weather conditions.