December 21, 2008
Some thoughts on our "toolkit"
The air quality is similar to what it has been all week (good in the east, problematic still in the San Joaquin Valley) so I'm going to wander a bit in this post.
If you have been checking on the GOES Aerosol and Smoke Product this week on the IDEA site, you will note that it is missing. GOES-12 suffered a thruster anomaly on December 4 while attempting a stationkeeping manuever. NOAA has switched over to the spare GOES-13 satellite. GOES-13 is in a different position (105°W instead of GOES-12's 75°W. It was stored at that location in case either GOES-E (our GOES-12) or GOES-W had a problem. Viewing from that location, the algorithm which runs on the GOES level 1 data to calculate the aerosol optical depth needs to have a new calibration table inserted and new lookup tables (to convert radiance to aerosol optical depth) created for the new view angles. In addition, GASP needs 28 days of dark pixels in clear air to "know" what a dark surface looks like from that orientation. We can expect GASP to return to a functioning product in a little over a month then.
From Scott Bachmeier at CIMSS comes the following information: "The Terra Spacecraft experienced a failure of its Science Formatter Equipment on 12/20/08 at approximately 5:00(UTC). As a result, no data from Terra is currently available. There is no current estimate on when the problem will be fixed, but the NASA recovery team is investigating the issue."
The OMI NO2 tropospheric data has not been available since December 19.
I was asked at the American Geophysical Union meeting what we will do for data if the current on-orbit sources (MODIS, MISR, GASP, etc.) reach the end of their lifetime (and some are well past their planned lifetime. I said that "we will be getting VIIRS on line in a little over a year". A colleague suggested to me "Retire early" might have been a better response. But this week's event with GOES-12 and Terra shows how fragile our viewing of this planet is. (Of course, I could blame Ralph Kahn for asking the question and jinxing these satellites).
Since the country is largely covered in clouds, I thought I would take a look at the reason for the continuing high particle concentration in the San Joaquin Valley (below).
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The four panels below show sulfate concentrations in air in 1989 (left) and 2007(right) from the CASTNET website. Below it shows the nitrate concentrations in air in 1989 (left) and 2007(right). Clearly, there is a "hotspot" for nitrate in the San Joaquin Valley and like the one east of Iowa, it is likely that agricultural nitrate use is a large source for each area.
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If you are interested in reading further about the sources of nitrates (and organics) in the SJV, I recommend the CA Air Resources Board site and especially the powerpoint by John Watson on that page.
Finally, for those who think that "acid rain" is a problem of the past, critical loads for sulfate range from 20 kg ha-1y-1 for calcium rich soils to 8 kg ha-1y-1 for more sensitive watersheds. Looking at the 2007 wet deposition map from CASTNET, you can see that much of the east is still being affected by acid rain.
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