A new global long-term satellite aerosol dataset from SeaWiFS measurements

July 1, 2011 — Click on image to enlarge.

July Highlights

Seasonal mean midvisible AOD, averaged over the SeaWiFS mission. Seasonal variability of major hotspots associated with aerosol sources such as desert dust or biomass burning is evident. Missing data are caused by persistent cloudiness, snow or ice, or darkness at the time of the SeaWiFS overpass, conditions for which aerosol retrieval is not presently possible.

Aerosols are small particles suspended in the atmosphere. They have diverse sources, sinks, and compositions, such as desert dust (most notably from the Sahara and east Asian deserts), sea salt, urban pollution, volcanic ash, biomass burning smoke, and sulphates and organic compounds from a variety of natural and anthropogenic process. The study of aerosols is important for many reasons:

1. Their direct and indirect effects on climate are complicated and not well-quantified.

2. Poor air quality due to high aerosol loadings in urban areas has adverse effects on human health.

3. Transported aerosols provide nutrients such as iron (from mineral dust and volcanic ash), important for fertilization of parts of the world’s oceans and tropical rainforests.

4. Knowledge of aerosol loading is important to determine the potential yield from the green solar energy sources.

We have developed a new aerosol dataset derived from Sea-viewing Wide Field-Of-View Sensor (SeaWiFS) measurements. The time series (1997-2010) is longer than existing records from other EOS era satellite instruments, and includes much of the strong 1997-1998 El Nino period. We include aerosol optical depth (AOD, a measure of atmospheric turbidity) in the mid-visible range of the spectrum (550 nm), and the Angstrom exponent, linked to particle size.

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