Friday, December 3, 2010

Dec. 3 - LOW WIND EVENT - Hazy today. High clouds but sunny and warming up today. Looking south from Las Cruces there is a thick haze. Even in mid-morning there is a haze in Las Cruces. The morning's sounding from Santa Teresa showed a very strong inversion causing this.
Some higher than normal PM2.5 concentrations last night at the project core site. Right now the trailer is located at the Fabian Garcia farm in west Las Cruces. The following plot shows the PM2.5 concentrations starting from yesterday and continuing till this afternoon.
Peak PM2.5 concentrations occurred at 10 pm last night at 50 µg/m3.The event lasted from 6 pm to 1 am this morning. The other gray line is the aerosol light scattering coefficient from the nephelometer. 

At 11 pm it looks like tonight is a repeat of last night. PM2.5 is high at the border sites. Peak PM10 was over 350 µg/m3 and PM2.5 nearly 100 µg/m3 tonight.
High clouds prevented satellite based aerosol detection and I haven't located good maps of AOD from MODIS or GOES. Late in the evening from my viewpoint in eastern Las Cruces I can see an elevated layer of particulates over the Mesilla Valley. I took this out my window over the neighbor's roof in foreground. The distant lights are from the Las Cruces Industrial Park on the West Mesa. This haze was pretty much what I saw last night. My guess is that the inversion is a few hundred meters and what we're seeing is local emissions of residential wood burning and dust.
No significant large wildfires going on in the area based on the NOAA HMS maps.
Calm winds in the area so I would not expect much transport. With this high sitting over us we'll likely see some strong inversions and higher than normal pollutant build-up in valley locations. Once pollutants build up we can see them from satellite. The map below is from the OMI (Ozone Monitoring Instrument) NO2 product that gives column integrated gridded NO2 concentrations over the globe. As the map shows, there is a hot spot of NO2 over the El Paso area from the various combustion sources (cars, trucks, industry, etc.). We typically see strong NO2 over power plants and urban areas. For example the Four Corners region is clearly visible in the map as well as Phoenix, Albuquerque, and Dallas-Ft. Worth. Looking at all these areas, you can't say that were not polluting our atmosphere on a regional scale!
We can see the result of subsidence observing the low dewpoint temperatures. They are around or below zero F. Looking at the forecast maps, a cold front is sliding toward us from the northeast and should bring a few changes by Saturday night. But looking at the long range forecast GFS model we will still be under a ridge and the possibilities of continuing low wind events. We are in a dry spell with little to no precipitation over the past month. The map below from the National Weather Service website shows percent of normal precipitation over the past 30 days. Lots of red, red, and more red. That red is less than 5 percent of normal. Not surprising given that we are in a moderate to strong La Nina phase and southern NM has tended to respond stronger to this than northern New Mexico.
The implications are without rain some of the dry lake beds that were wet may be drying out and could be spots of dust emissions given time.

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