Topic: No Data for Ozone - wxaqirss.php Script

[BKS97]

For some time now I’ve noticed that Real-time AQI - Pollutant Details for ozone is showing “no data” on my wxaqirss.php page.  I have not been able to fix the problem and wonder if someone can point me in the right direction.  Thanks.

https://sartelleastweather.com/wxaqirss.php

[Vasco]

It may be that the St Cloud sensors do not measure ozone: see https://aqicn.org/city/usa/minnesota/st.-cloud/, which shows only PM2.5

If you scroll down, this data is provided by the Minnesota Pollution Control Agency too.

[BKS97]

Thanks for your reply. According to the Minnesota Pollution Control Agency, St. Cloud is one of 17 ozone monitoring sites around the state. Also, I remember that the indicator was reporting the ozone level previously.

[Vasco]

Maybe the sensor is broken. Have you tried contacting them?

See https://www.pca.state.mn.us/air-water-land-climate/current-air-quality-conditions - no ozone, no PM10

[BKS97]

I did discover this on the MPCA website: The MPCA produces daily air quality forecasts for levels of fine particles and of ground-level ozone (from March through October) in eighteen locations in Minnesota.

I also read online that higher ozone levels more likely occur during the warmer months.

So that likely explains why there are no current ozone levels being reported on my site right now.  I’m glad to have learned this today!

[Vasco]

So that likely explains why there are no current ozone levels being reported on my site right now.

Site does say it produces a forecast from March through October. . . I would expect it still to be measuring ozone.

Here at 56°N (https://aqicn.org/station/united-kingdom/edinburgh-st-leonards) ozone is frequently the dominant pollutant, even at this time of year.

[BKS97]

Good point. Thanks.  I will have to look into this further.

[Vasco]

And your current forecast in wxaqirss.php shows ozone as dominant pollutant tomorrow 

[Vasco]

Good point. Thanks.  I will have to look into this further.

I did, too. Here's what MPCA have to say:

"St Cloud monitors for PM2.5 year round, and ozone from March 1 to October 31. Ozone during the winter is low due to limited sunlight and photochemistry. This is also the time the ozone monitors are recalibrated and repaired/maintained.  The closest PM10 monitor is at Blaine…our PM10 network is rather limited compared to the PM2.5 network."

[BKS97]

Yes, the “Real-Time AQI - Pollutant Details” readings for ozone on my wxaqirss.php page will continue to show “No Data” until the MPCA sensors readings are reported again starting on March 1.  In their reply to me, the MPCA also explained why the one- and two-day ozone forecasts are reported during the winter months even though their sensors are down for maintenance:

“In the cool season ozone is always Green due to limited sunlight and photochemistry. During this time we fill in ‘Good’ for the forecast.”

Makes good sense to me.  Glad to have learned more about how this all works.

https://sartelleastweather.com/wxaqirss.php

[Vasco]

Glad to have learned more about how this all works.

Me too! But I don't understand how that squares with us getting ozone as dominant pollutant here, at 56°N, during winter. . .

[BKS97]

Yes, the “Real-Time AQI - Pollutant Details” readings for ozone on my wxaqirss.php page will continue to show “No Data” until the MPCA sensors readings are reported again starting on March 1.  In their reply to me, the MPCA also explained why the one- and two-day ozone forecasts are reported during the winter months even though their sensors are down for maintenance:

“In the cool season ozone is always Green due to limited sunlight and photochemistry. During this time we fill in ‘Good’ for the forecast.”

Makes good sense to me.  Glad to have learned more about how this all works.

https://sartelleastweather.com/wxaqirss.php

March 1st and meteorological spring are at hand, so the good folks at the MPCA have their ozone monitors operational again, just like they said they would. . .

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