RESEARCH ARTICLE


Comparison of Aerosol Optical Depth (AOD) Derived from Ground-Based LIDAR and MODIS



P.W. Chan*
Hong Kong Observatory, 134A Nathan Road, Hong Kong, China.


© 2009 P.W. Chan.;

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Hong Kong Observatory, 134A Nathan Road, Hong Kong, China; E-mail: pwchan@hko.gov.hk


Abstract

The performance and application of AOD products from the Moderate Resolution Imaging Spectroradiometer (MODIS) are studied by comparing with the AOD derived from the ground-based Doppler LIDAR inside the Hong Kong International Airport (HKIA). The backscattered power data of the LIDAR are used to determine the extinction coefficient profile, from which the AOD is calculated. The AOD determined from the LIDAR is found to have good quality by comparing with the AOD measurements from a hand-held sun photometer at HKIA over a period of three months, and as such it is used to study the quality of AOD estimated from MODIS. The 1-km resolution AOD product from MODIS is found to have better correlation with the LIDAR AOD in comparison to the 10-km resolution product. Moreover, since AOD is a column-integrated quantity, its application to the monitoring of the surface visibility changes should be made with caution during the presence of elevated layers of higher aerosol concentrations. Examples of the effects of such elevated aerosol layers are studied.

Keywords: Aerosol optical depth, MODIS, LIDAR, Visibility.