Tuesday, December 7, 2010

Dec. 6 - Regional Haze Event - A hazy afternoon, high clouds, and above normal temperatures characterized the weather today. Breezy early morning but winds diminished during the daylight hours. A slow build-up of particulates starting in the morning and peaking in the evening. We had some southerly wind flow that I believe brought in a hazy airmass. I would need to run some HYSPLIT backtracjectories to confirm this. Haze visible in Las Cruces in the afternoon near sunset and very heavy in the evening. I could faintly see the particulates in bright headlights at around 9 pm. An interesting sequence of PM at the Sunland Park City Yard site below shows concentrations lowest in the early morning at 4 am and increasing throughout the day. I can almost see the local evening low wind peaks showing up at 6 pm and 8 pm within this regional build-up.
A different pattern for the Anthony Elementary site but we see a morning and evening peak in particulates. It is important to note that peak PM10 is higher here than at Sunland Park. Peak hourly PM10 was 275 µg/m3 at 6 pm. Peak PM2.5 was 39 µg/m3 at the same time.

The Las Cruces west mesa site showed a ramp-up of PM10 as well but not as striking as in Sunland Park
This evening's Air Quality Index (AQI) showed moderate levels in south-central New Mexico and west El Paso County. This pretty much matches what we see in the NMED monitoring.
The aloft haze layer is not visible in tonight's 1 am sky compared to this past weekend. Still lots of light scattering in this image. This view is looking toward the southwest overlooking Las Cruces.
The past day's AQI animation shows this event picking up in the evening around 8 pm MST.

Tomorrow's AQI doesn't show the moderate area in our area.

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