tag:blogger.com,1999:blog-6168620747792092240.post2588723316781421305..comments2024-03-27T15:09:59.039-06:00Comments on Wasatch Weather Weenies: Limitations of Purple Air ObservationsJim Shttp://www.blogger.com/profile/15799757451626876963noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-6168620747792092240.post-42330064334835083412021-08-06T15:01:44.296-06:002021-08-06T15:01:44.296-06:00I've appreciated PurpleAir (PA) ever since dis...I've appreciated PurpleAir (PA) ever since discovering them during the 2017 fires in northern California. I agree with your observations, but they're missing a couple of very significant workarounds, that I wish PA -- or at least their marketing department -- should be pointing out. (Generally I highly dislike marketing department strategies, but PA's seems to be too humble?)<br /><br />Do not use the default settings the one first sees in the lower left control panel. 1) Instead of using "none" as a conversion factor, I use the LRAPA standard. 2) Uncheck "Inside Sensors"; unchecked should be the default, except for the rare person who's only looking at the map for personal data. 3) Ten minute averaging gives an OK, overall picture of wide areas, but "Show Realtime" does, too, plus it shows up-to-the-minute data that I've found extremely useful for my local (neighborhood) area.<br /><br />It's important to note, that even if these instruments are not 100% accurate in 100% of the instruments, I've concluded they're close to 100% consistent when compared to each other, and when one mentally filters out the very few instruments that are failing. Most failures are immediately obvious, and easily discounted when one can see the errors as compared to other, obviously functional instruments.<br /><br />PA's data filtering on their map is too weak when it comes to discounting the obvious failures mentioned above, but again, it seems to lean to their customer's point of view rather than the more public point of view. E.g. when one of the two lasers is obviously failing, the data from the failing laser is still included in the air quality averages. Also, when the whole instrument is not functioning, a gray dot for that instrument is shown on the map... I just saw one that's been appearing on the map for over a hundred days!<br /><br />But even the gray dots can provide useful data in some cases, e.g. when power goes out in an area with a few or more instruments, one can see just by looking at that area of the map not only where power was lost, but when it was lost.<br /><br />Finally, I've personally benefited immensely from PA maps during fire season. With the settings I recommended above, and in my area that now has dozens if not a hundred (in a wider area) instruments, I can SEE smoke travelling minute by minute across the city and the county. The qualitative (even if not a specific-standard, quantitative) accuracy of is astounding! Alongside real-time wind direction maps (like Windy.com), I've successfully predicted when it's safe to spend time outside, and for approximately how long.<br /><br />Granted, typical observers will not (at least immediately) know how to interpret PA and Windy to make their own assessments as I do, practically routinely. But the potential for mass consumption of raw but useful air quality data that's already available is, I have to say again, astounding!<br /><br />(BTW, clicking on the "Preview" button just brought up a blank block, making me fear that my slow, 20 minutes of writing just disappeared into space. Fortunately it was all still there when I clicked on the back arrow to return to the the previous web page. Got mad at myself for not saving my work to the clipboard before clicking that Preview button. FYI, right after I clicked the Preview button I saw an error message (that looked like it came from Blogger), but it popped up then disappeared too quickly to read. (I am signed into Blogger.) Now we'll see if the Publish button works...Preternathttps://www.blogger.com/profile/15466714916580893886noreply@blogger.comtag:blogger.com,1999:blog-6168620747792092240.post-40203239784766013842020-01-09T16:47:21.002-07:002020-01-09T16:47:21.002-07:00Thanks for pointing that out. I assume you mean t...Thanks for pointing that out. I assume you mean this site: https://aqandu.org/? If so, I don't think what is being used for television broadcasts and by many people is the conversion factor data. Jim Shttps://www.blogger.com/profile/15799757451626876963noreply@blogger.comtag:blogger.com,1999:blog-6168620747792092240.post-82854575736764791662020-01-08T19:46:43.844-07:002020-01-08T19:46:43.844-07:00There is a conversion factor available in the lege...There is a conversion factor available in the legend on the PurpleAir map called AQandU created by Kerry Kelly specifically for PurpleAir sensor data for Salt Lake valley during the winter time.Malloryhttps://www.blogger.com/profile/00991136381767486235noreply@blogger.comtag:blogger.com,1999:blog-6168620747792092240.post-51872125772684059932019-12-20T13:14:47.313-07:002019-12-20T13:14:47.313-07:00Thanks. I should have noted that, although my com...Thanks. I should have noted that, although my comment about the clean east Bench was supported by the outdoor sensors near foothill and I-215 where several have readings ≤10.Jim Shttps://www.blogger.com/profile/15799757451626876963noreply@blogger.comtag:blogger.com,1999:blog-6168620747792092240.post-11107740160282484452019-12-20T11:17:28.986-07:002019-12-20T11:17:28.986-07:00It's worth pointing out that observations on t...It's worth pointing out that observations on the Purple Air map that are circled in black denote *indoor* sensors, which tend to be cleaner. And, there are a lot more indoor sensors in the north/east part of the valley than in other areas.<br /><br />If only outdoor sensors are displayed, the pollution distribution is less extreme. Though, I do agree that the elevated areas of the valley are cleaner than the lowlands.Anonymousnoreply@blogger.com