13 Jul 2022
13 Jul 2022

Retrievals of Precipitable Water Vapor and Aerosol Optical Depth from direct sun measurements with EKO MS711 and MS712 Spectroradiometers

Congcong Qiao1,2, Song Liu1,2, Juan Huo1, Xihan Mu3, Ping Wang4, Shengjie Jia5, Xuehua Fan1, and Minzheng Duan1,2 Congcong Qiao et al.
  • 1LAGEO, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China
  • 2College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
  • 3State Key Laboratory of Remote Sensing Science, Beijing Normal University, Beijing, 100875, China
  • 4Royal Netherlands Meteorological Institute (KNMI), De Bilt, the Netherlands
  • 5Beijing Keytec Technology Co., Ltd., Beijing, 100102, China

Abstract. Based on the strict radiative transfer algorithm, a new method is developed to derive the Precipitable Water Vapor (PWV) and Aerosol optical depth (AOD) from the ground-based measurements of direct sun irradiance. The attenuated direct irradiance from 300 nm to 1700 nm with FWHM of 6.5 nm are measured by a pair of grating spectroradiometers MS711 and MS712, located at the Institute of Atmospheric Physics, Chinese Academy of Sciences (39.98° N, 116.38° E), from June 2020 to March 2021. Compared to that of regular sun photometers such as CIMEL and POM, a strong water vapor absorption band near 1370 nm is introduced to derive PWV for the relatively dry atmosphere. The PWV and AOD inversion results obtained by EKO are compared with the synchronous data of CIMEL, and the two are highly consistent. The correlation coefficient, mean bias and standard deviation of PWVEKO and PWVCIMEL are 0.999, -0.027 cm (-3.57 %) and 0.054 cm (3.93 %) respectively, and the relative deviations of the differences between the two are slightly larger for drier air (PWV<5 mm) and lower solar elevation angle. The correlation coefficients of AODEKO and AODCIMEL at 380, 440, 500, 675, 870, 1020 nm are greater than 0.99, and the relative deviations are between -13.59 % and 9.37 %.

Congcong Qiao et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-315', Anonymous Referee #3, 17 Aug 2022
    • AC1: 'Reply on Referee #3', Congcong Qiao, 23 Oct 2022
  • RC2: 'Comment on egusphere-2022-315', Anonymous Referee #2, 26 Aug 2022
    • AC2: 'Reply on Referee #2', Congcong Qiao, 23 Oct 2022

Congcong Qiao et al.

Congcong Qiao et al.


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Short summary
We established a spectral-fitting method to derive precipitable water vapor and aerosol optical depth based on strict radiative transfer theory by the spectral measurements of direct sun from EKO MS711 and MS712 spectroradiometers. The retrievals were compared with that of collocated CE-318 Photometer, the results showed a high degree of consistency. Besides the water vapor absorption bands near 940 nm, that near 1370 nm is demonstrated more suitable for water vapor retrieval of drier atmosphere.