June 4, 2004 – Tucson Dust Community Analysis PPT Please add your content by downloading this PPT, and returning to email@example.com
June 4, 2004 – Tucson Dust Event Lee Alter, WRAP
Last Friday (June 4) was the haziest day I've seen since moving to Tucson about 14 months ago. It was on the font page of the paper/etc. The visual range was literally 3-4 miles. It was much larger than just the valley and extended pretty high up too.
I spoke with the local NWS science officer and the Pima County air monitoring chief, and there seems to be consensus that this dust originated from thunderstorms in west TX, NM, and northern Mexico (Chihuaha), probably during the evening of June 3, although there were storms on the 2nd too. It blew in here over night, then mixed down in the morning. People in the foothills actually smelled smoke at the base of the haze layer, probably because there were some fires in the Sierra Vista area which got mixed into the dust cloud, but it was probably mostly dust (see next paragraph).
I've attached some continuous monitoring data from a site in Tucson. The PM data are from beta attenuation monitors. Data from other sites look the same. PM10 reached a peak of 530 ug/m3. PM2.5 was high too, but only 13% of the PM10 value, which sounds like dust to me. And as you can see, these levels are not associated with local wind speed.
I know this is one of the dust source types you are trying to identify in our project, but I thought I'd bring it to your attention as a possible case study, even though it wasn't an IMPROVE sampling day. (Might be good for the inter-RPO FASTNET project too.) I expect to get some pictures soon. I'd really like to overlay wind speed data (from ASOS, doppler radar, whatever) with land type/use information to see if the dust may have come from areas that are anthropogenically disturbed. Unfortunately, I think the highest winds occured at night, so there might not be any good visual imagery to verify the wind/land/dust source relationship.
Vic: > You're not kidding. Those are pretty impressive PM10 values for
> non-locally generated dust. This might be a good "known" case to take a
> look at and see if there is any way to tease out what happened and apply
> it to the IMPROVE data.
Thanks Rudy. I would appreciate it if you could add some of those photos in there. By the way, there weren't any thunderstorms in Tucson on June 4. There were some cumulus clouds in the area during the day, which show up in the MODIS image, but the ones that caused all the wind were well to the east the night before. I'll send you something I just got from DRI on that, which you might want to add too. - Lee
The infrared GOES image (06:45 UTC (11:45 pm pacific time) probably shows the thunderstorm outflow from mesoscale convective systems in NM/MX/TX. It's the light colored yellow arc of clouds in SE Arizona. Pretty impressive outflow.
There was another strong outflow this past week (early am on June 3rd) in Eastern NM/West TX.
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