November 30, 2007
Special Feature: Some dust in Cape Town and Farewell
As the GEO IV Plenary Meeting wraps up, we make our final special post on air quality in South Africa for Friday.
All the air quality activity is on the western coast of South Africa near Cape Town, so we'll start with a true color image of that area from the NASA MODIS sensor on the Terra satellite (left image). Look closely near the coast just north of Cape Town to see a small yellowish plume of dust over the Atlantic Ocean. On the right is a zoomed in version with the plume circled in red. This is confirmed with the EUMETSAT algorithm that can detect dust, shown in pink/magenta in this dust image of southwest sector of the full disc.
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The ground-based monitors from the City of CapeTown show a huge increase in PM10 levels from one of the monitors during the middle of the day, including the time as the MODIS image. This partially confirms the potential of dust or other coarse pollution seen by MODIS. (Recall that PM10 is a measure of particles in the air that are less than 10 microns in diameter and the 24-hour average health standard for PM10 is 50 micrograms per cubic meter (ug/m3).)
(Please note that these data are preliminary "live data" that have not been validated and that the standard is an average of these points, not any single value).
The SCIAMACHY UV index was 11 again Friday in Cape Town, an indicator of extreme risk of harm from unprotected sun exposure. The Cape Town web cam has beautiful sunny, slightly hazy skies.
We enjoyed our virtual week in Cape Town and wish the attendees of the GEO Plenary meeting safe travels in clear skies!
Posted by Jill Engel-Cox at November 30, 2007 6:45 PM | TrackBack