Improvements to the OMI near-UV aerosol algorithm using A-train CALIOP and AIRS observations

O Torres,C Ahn,Z Chen

doi:10.5194/amt-6-3257-2013

Abstract

Abstract. The height of desert dust and carbonaceous aerosols layers and, to a lesser extent, the difficulty in determining the predominant size mode of these absorbing aerosol types, are sources of uncertainty in the retrieval of aerosol properties from near-UV satellite observations. The availability of independent, near-simultaneous measurements of aerosol layer height, and aerosol-type related parameters derived from observations by other A-train sensors, makes possible the use of this information as input to the OMI (ozone monitoring instrument) near-UV aerosol retrieval algorithm (OMAERUV). A monthly climatology of aerosol layer height derived from observations by the CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) sensor, and real-time AIRS (Atmospheric Infrared Sounder) carbon monoxide (CO) observations are used in an upgraded version of the OMAERUV algorithm. AIRS CO measurements are used as an adequate tracer of carbonaceous aerosols, which allows the identification of smoke layers in regions and seasons when the dust-smoke differentiation is difficult in the near-UV. The use of CO measurements also enables the identification of high levels of boundary layer pollution undetectable by near-UV observations alone. In this paper we discuss the combined use of OMI, CALIOP and AIRS observations for the characterization of aerosol properties, and show an improvement in OMI aerosol retrieval capabilities.

Highlights

Since the discovery of the near-UV capability of absorbing aerosols detection from space over a decade ago (Hsu et al, 1996; Herman et al, 1997; Torres et al, 1998), the UV Aerosol Index (AI), calculated from observations by the Total Ozone Mapping Spectrometer (TOMS) family of sensors, and more recently by the Ozone Monitoring Instrument (OMI), has been used to map the daily global distribution of UV-absorbing aerosols such as desert dust particles as well as carbonaceous aerosols generated by anthropogenic biomass burning and wildfires (Herman et al, 1997), and volcanic ash injected in the atmosphere by volcanic eruptions (Seftor et al, 1999)
The effect of using the CALIOP Zclp climatology as input in the OMI inversion algorithm was evaluated by comparing the optical depth from the OMAERUV algorithm to AERONET observations (Holben et al, 1998) using both the standard algorithm aerosol height assumption and the aerosol altitude extracted from the CALIOP climatology described here
OMAERUV aerosol extinction optical depth (AOD) retrievals within a radius of 40 km of the AERONET site were compared to ground-based observations within a ± 10 min window (Ahn et al, 2013)

Summary

Introduction

Since the discovery of the near-UV capability of absorbing aerosols detection from space over a decade ago (Hsu et al, 1996; Herman et al, 1997; Torres et al, 1998), the UV Aerosol Index (AI), calculated from observations by the Total Ozone Mapping Spectrometer (TOMS) family of sensors, and more recently by the Ozone Monitoring Instrument (OMI), has been used to map the daily global distribution of UV-absorbing aerosols such as desert dust particles as well as carbonaceous aerosols generated by anthropogenic biomass burning and wildfires (Herman et al, 1997), and volcanic ash injected in the atmosphere by volcanic eruptions (Seftor et al, 1999). To differentiate between absorbing aerosol types (carbonaceous or desert dust), the TOMS algorithm used geographical location and surface type considerations (Torres et al, 2002)

Methods

Results

Conclusion