大尺度水热通量观测系统的研制

基于闪烁理论、孔径平均效应及莫宁-奥布霍夫相似理论(MOST),成功研制了大尺度水热通量观测系统样机YZ01,该系统主要由发射器、接收器、云台、瞄准器、气象传感器、数据采集器、数据处理软件、远程无线数据传输模块、太阳能供电系统等部分组成.该系统发射器平均功耗3W,接收器功耗1.8 W,比德国的BLS450和荷兰的LAS都更省电;发射器光源功率为100 mW,比荷兰LAS的80 mW更强,在同样条件下,YZ01接收器接收到的闪烁光解调信号比荷兰LAS强14%左右,说明在相同的安装距离下,YZ01比荷兰LAS更适于在能见度低的条件下使用,或者说在同样的环境条件下,YZ01比荷兰LAS可以测量更远的距离.YZ01在北京密云站与荷兰Kipp＆Zonen公司的LAS、美国Campbell公司的涡度相关测定系统进行了短期的应用对比试验,结果为:空气折射指数的结构参数Cn2、感热通量H、潜热通量LE的日变化趋势都非常一致;YZ01与LAS之间Cn2的线性拟合系数为0.98,相关系数为0.7;H的线性拟合系数为0.90,相关系数为0.93;YZ01通过余项法算出的LE与涡度相关直接测得的LE的线性拟合系数为1.07,相关系数为0.78.YZ01在青海阿柔站与德国Scintec公司的BLS450进行对比结果为:空气折射指数的结构参数Cn2、感热通量H、潜热通量LE的日变化变化趋势也都非常一致,YZ01与BLS450之间Cn2的线性拟合系数为1.25,相关系数为0.93;H的线性拟合系数为1.17,相关系数为0.99;YZ01通过余项法算出的LE与涡度相关测定系统测得的LE的线性拟合系数为1.03,相关系数为0.84.表明该研究所研制的大尺度水热通量观测系统不仅可以达到国外同类仪器同样的应用水平,而且比国外同类产品更省电、比荷兰LAS更适应在低能见度条件下使用.

Development of a Measuring System for Surface Energy and Water Vapor Fluxes at Large Scale

Based on the extension of the first-order perturbation theory of optical scintillation and Monin-Obukhov similarity theory, an apparatus YZ01 for measuring the refractive index structure constant C²_n and for measuring surface fluxes, such as sensible heat flux and latent heat flux along a long line-of-sight path, was developed. This apparatus consists of a transmitter part, a receiver part, an optical alignment part and a signal processing part. Signal modulation and demodulation method is used to distinguish the EM signal from background radiation. Filter and feedback circuitry is used to increase signal to noise ratio. The power of YZ01 transmitter is 3W average, and the receiver only 1.8W. The feature and accuracy of YZ01 was tested by comparing with Kipp & Zonen LAS and Scintec BLS450 over Miyun site, Beijing and Arou site, Qinghai. The results showed: ①The modulate signal of YZ01 is about 14% stronger than Kipp&Zonen LAS over Miyun site. ②The slope of linear regression and the correlation coefficient of C²_n between YZ01 and LAS is 0.98 and 0.7 over Miyun site. ③The slope of linear regression and the correlation coefficient of H between YZ01 and LAS is 0.90 and 0.93 over Miyun site. ④The slope of linear regression and the correlation coefficient of LE between YZ01 and LAS is 1.07 and 0.78 over Miyun site. ⑤The slope of linear regression and the correlation coefficient of C²_n between YZ01 and BLS450 is 1.25 and 0.93 over Arou site. ⑥The slope of linear regression and the correlation coefficient of H between YZ01 and BLS450 is 1.17 and 0.99 over Arou site. ⑦The slope of linear regression and the correlation coefficient of LE between YZ01 and BLS450 is 1.03 and 0.84 over Arou site.