Abstract

ABSTRACT Micropulse lidar (MPL) cannot directly retrieve the aerosol extinction coefficient under cloudy conditions and at night. Therefore, we used ground visibility, Fernald’s near-end solution method, and the linear correlation between the near-end lidar signal (photons) and ground aerosol extinction coefficient (correlation coefficient = 0.98), to calculate the lidar constant and lidar ratio (LR). We compared the aerosol optical depth (AOD) retrieved from MPL and the AOD retrieved from the multifilter rotating shadowband radiometer (MFRSR-7) at the same band (532 nm). The correlation coefficient was 0.77. The vertical distribution of aerosols in daytime and nighttime during summer was obtained from lidar in July at 00:00 and 12:00 Beijing time (UTC+8). In daytime, under clear sky conditions, the distribution displayed a unimodal and peak at approximately 2000 m. The distribution at night was more complicated than that in the day, with three results. The first was monotonically decreasing from ground to upper layer, with a peak at 600 m and two peaks at approximately 1200 m. In general, the aerosol extinction coefficient at nighttime is higher than that at daytime below 1200 m. The near-ground extinction coefficient at night is higher than in the day.

Highlights

  • Aerosol vertical distribution characteristics have critical effects on both weather and climate

  • Assuming that lidar ratio (LR) is constant at Aerosol and Air Quality Research | https://aaqr.org this point, the aerosol vertical extinction coefficient can be calculated

  • We calculated LR dynamically using ground visibility according to linear relationship between the near-end lidar signal and aerosol extinction coefficient (Lin et al, 2013)

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Summary

INTRODUCTION

Aerosol vertical distribution characteristics have critical effects on both weather and climate. Assuming that LR is constant at Aerosol and Air Quality Research | https://aaqr.org This point, the aerosol vertical extinction coefficient can be calculated. Determining the boundary value and reasonable calibration is crucial for accurate retrieval (Liu et al, 2008) To solve this problem, we calculated LR dynamically using ground visibility according to linear relationship between the near-end lidar signal (photons) and aerosol extinction coefficient (Lin et al, 2013). We calculated LR dynamically using ground visibility according to linear relationship between the near-end lidar signal (photons) and aerosol extinction coefficient (Lin et al, 2013) This method can be used to retrieve the lidar aerosol vertical extinction coefficient under any sky conditions

Micropulse Lidar
Foreword Scattering Visibility Meter
Multifilter Rotating Shadowband Radiometer
RETRIEVAL ALGORITHM
Calculation of Ground Aerosol Extinction Coefficient
Calculation of Dynamic LR from Ground Visibility
Calculation of Dynamic LR
Validation
Vertical Distribution Characteristics
CONCLUSIONS
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