Mfrsr Instrument Observations Of Aerosol Optical Thickness

The paper mainly includes two aspects. One is observation of aerosol optical depth using MFRSR (multi-filter rotating shadow-band radiometer), the other is the analysis of aerosol optical properties in the region of Xianghe. Firstly, MFRSR is a ground-based instrument and used to make measures of irradiance and aerosol. It uses automated rotating shadow-band technique to alternatively make measurements of total horizontal and diffuse horizontal irradiances at seven wavelengths simultaneously, and then infer direct normal irradiance. In addition to broadband Silicon detector measures total solar irradiance, center wavelengths of the other six wave bands are 414.3nm, 495.3nm, 613.7nm, 671.5nm, 867.6nm and 939.3nm. This paper introduces the instrument of MFRSR, the method of calibration and data processing, and then analyses statistical properties of aerosol using observation of MFRSR during 2004-2005 in Xianghe. In order to illuminate the reliability of observing aerosol optical depth with MFRSR, we compare the results of MFRSR with AERONET data. It shows the mean differences of the two results respectively are -0.021,-0.009,-0.004 at the wavelengths of 500nm, 670nm, 870nm, and the standard deviations are 0.067,0.051,0.050 . We also discuss the reasons for deviation of the two. In addition, we analyze the relationship between aerosol optical properties and meteorological elements in region of Xianghe, such as surface visibility, relative humidity, horizontal wind speed and so on. The conclusion is that there is negatively linear relationship between aerosol optical depth and surface visibility, and aerosol optical depth is positively correlative with relative humidity, aerosol optical depth increases with the increasing of relative humidity. Aerosol optical depth increases slowly with the increase of relative humidity before deliquescence of soluble particles. And Aerosol optical depth increases quickly with the increase of relative humidity after deliquescence of soluble particles. And aerosol optical depth is correlative with horizontal speed. As the horizontal speed increases, aerosol optical depth decreases quickly and then increases slowly. In the end we analyze seasonal change of aerosol optical properties in the region of Xianghe and the reasons of change of aerosol optical properties from the aspect of dominant wind.