Retrieving near‐global aerosol loading over land and ocean from AVHRR

• Published in: Journal of geophysical research. Atmospheres Vol. 122; no. 18; pp. 9968 - 9989
• Main Authors: Hsu, N. C., Lee, J., Sayer, A. M., Carletta, N., Chen, S.‐H., Tucker, C. J., Holben, B. N., Tsay, S.‐C.
• Format: Journal Article
• Language: English
• Published: Washington Blackwell Publishing Ltd 27-09-2017
• Subjects: Advanced Very High Resolution Radiometer; aerosol; Aerosol optical depth; Aerosol properties; Aerosol Robotic Network; Aerosols; Airborne particulates; Algorithms; Arid regions; Arid zones; AVHRR; Climate studies; Confidence intervals; Data; Equatorial regions; Geophysics; Global aerosols; Imaging techniques; Mathematical models; Meteorological satellites; MODIS; Oceans; Optical analysis; Physics; Radiometers; Reflectance; Remote sensing; Resolution; retrieval; satellite; Satellites; Sea-viewing Wide Field-of-view Sensor; Sensors; Spaceborne remote sensing
• ISSN: 2169-897X; 2169-8996
• DOI: 10.1002/2017JD026932

The spaceborne advanced very high resolution radiometer (AVHRR) sensor data record is approaching 40 years, providing a crucial asset for studying long‐term trends of aerosol properties regionally and globally. However, due to limitations of its channels' information content, aerosol optical depth (AOD) data from AVHRR over land are still largely lacking. In this paper, we describe a new physics‐based algorithm to retrieve aerosol loading over both land and ocean from AVHRR for the first time. The over‐land algorithm is an extension of our Sea‐viewing Wide Field‐of‐view Sensor and Moderate Resolution Imaging Spectroradiometer (MODIS) Deep Blue algorithm, while a simplified version of our Satellite Ocean Aerosol Retrieval algorithm is used over ocean. We compare retrieved AVHRR AOD with that from MODIS on a daily and seasonal basis and find, in general, good agreement between the two. For the satellites with equatorial crossing times within 2 h of solar noon, the spatial coverage of the AVHRR aerosol product is comparable to that of MODIS, except over very bright arid regions (such as the Sahara), where the underlying surface reflectance at 630 nm reaches the critical surface reflectance. Based upon comparisons of the AVHRR AOD against Aerosol Robotic Network data, preliminary results indicate that the expected error confidence interval envelope is around ±(0.03 + 15%) over ocean and ±(0.05 + 25%) over land for this first version of the AVHRR aerosol products. Consequently, these new AVHRR aerosol products can contribute important building blocks for constructing a consistent long‐term data record for climate studies.
Key Points
The Deep Blue algorithm can now be applied to AVHRR measurements and provide near‐global aerosol information over land and ocean
Nearly 40 years of aerosol data records can be constructed using this new AVHRR algorithm
The key factors in surface reflectance determination are characterized