Wednesday, December 22, 2010

Dec. 22 - Possible Eastern Airmass Intrusion Event - More morning haze across Mesilla Valley. The forecasted high for today is 71F which is roughly 14 degrees above normal. Winds will not be an issue today. Below is the 22 UTC (3 pm) forecast for winds today from the RUC2 model. As the map shows we are expecting SE winds on the eastern part of the area and SW winds out west.
Temperatures will return to normal after a storm passes over us on Thursday. The western portion of the study area may get some precipitation on Thursday morning based on the forecast model below. The movie shows an isosurface of relative humidities greater than 95% from 5 am today to 5 pm on Friday
video 
At the core site today we are having a low wind high PM event this evening. PM10 peaked at 138 µg/m3 and PM2.5 at 47 µg/m3 at 9 pm. That's a PM2.5/PM10 ratio of 0.34, which is higher than I would have expected for just dust. I may guess that we're probably seeing some residential wood burning. The temperature at the LC airport is around 50F and 47F at my house on the east side.
Scanning across the NMED network here are the plots for today. First here is PM10 at Chaparral.

Here is Deming PM10

Here is Sunland Park City Yard PM2.5

and finally this is Anthony PM2.5
They all have the early evening PM spike. One hypothesis is the due to the large scale weather pattern this afternoon. We have a backdoor cold front coming in from the northeast. Behind the front we have a cold air mass from the midwest. The map below provides some justification for this with high tropospheric NO2 over most of eastern New Mexico.
One final piece of information is from the AERONET observation at WSMR HELSTF. The Aerosol Optical Depth observation on the far right of the plot is today's. Although this is only preliminary data and there were clouds today, it is highest AOD this month.
So right now I'll call this a "Midwest or Eastern airmass intrusion event." Backtrajectories would help out in this analysis.

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