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2024 Air Quality Index (AQI) Update

2024 AQI Revisions
Image courtesy of IQAir

On May 6th the U.S. Environmental Protection Agency rolled out a change to the Air Quality Index (see table above). We didn’t receive notification of this until yesterday. These modifications are now live on the website — both in current conditions and in the weather history tables effective July 19, 2024.

Keep in mind, we apply an EPA correction factor to the AQI reading. If you visit other air quality websites or apps, the readings may seem incorrect if, by default, they report raw AQI. The most accurate way to compare our sensor readings to others nearby is to visit https://fire.airnow.gov/. Click the search icon, type in “Marquette, MI” and hit enter.

Why do we correct the AQI? Because researchers at the EPA discovered that by applying an algorithm to our “low-cost” (~$400) PurpleAir sensor its readings better approximate the higher-cost, more accurate government sensor readings. Experiments were conducted within the context of wildfire smoke pollution — the thing people are most concerned about here.

It Ain’t Broke If You Don’t Know

My apologies to those who endured stale data on the home page almanac & weather history page on Friday & Saturday. The app that uploads data from our weather telemetry to the website (hosted downstate) had inexplicably stopped. It wasn’t locked up. It just wasn’t running the schedule. I could manually update, but not automatically. A restart of the app solved the issue. I’ve used that utility for years now and never seen anything like that. My thanks to a regular site visitor, Julie, who alerted me and sent me a kind note to boot! Please do not hesitate to use the contact form if you notice something is awry.

Fortunately, I have multiple, independent systems so when one fails, the others continue. For example, conditions data is uploaded every 3 seconds by two different apps. Forecasts are downloaded directly by the web server (and I can switch to a back up process when the provider is down). Even if we lose power at our property, the forecasts and alerts will continue to update indefinitely.

I am constantly checking for and fixing bugs — both in my own code and those generated by our various providers. Between our regular visitors, my wife and my own (normally) keen eye no error on the site goes undetected for long.

Earlier in the week you may have noticed missing forecast icons. That was due to a couple unpublished changes NOAA (parent organization to the National Weather Service) pushed out to their forecast API. Upon investigation I saw that they had started to omit the domain (!) from the image URLs. So I had to prepend the domain to all their file locations. Also they started sending an empty data field for wind direction when the speed is 0. If you know anything about programming, the first error routine is to check for empty data and reject it because all valid data must have a value. Not in this case! So I manually force a “N” (northerly) wind direction which was the default they had been supplying in that case for years. Once I realized this wasn’t just a temporary goof on NOAA’s part (which has happened multiple times and self corrects within an hour or so), I ultimately switched over to a “legacy” source for forecast data for a time until I could make updates to the affected forecast files.

My philosophy is that the user interface — the portion of the website the visitor sees and interacts with — should be simple & dependable not trendy. No infinitely scrolling pages which stutter and lock up while you search for the information you need! No bloated multi-megabyte pages that track you and interrupt you with pop ups while you’re trying to read.

Behind the scenes of this seemingly modest (perhaps even “old-fashioned”) website are tens of thousands of lines of code written by yours truly. The weather history page alone is a complex series of mathematical calculations (using standard equations that have been accepted for decades). Everything has been quadruple checked for accuracy against other sources.

We are about to step into our 10th year of recording data just south of downtown Marquette. The aim is to provide a long-term, independent, reliable source of weather data completely free and available to the public.

Thank you to our many regular (and irregular — you know who you are) visitors!

Real-time Air Quality Monitoring Now Available

We have acquired & installed an air quality sensor as part of our real-time atmospheric telemetry. You can view it’s 10 minute average Air Quality Index (AQI) at marquette.purpleair.com.

Given our proximity to vast tracts of unspoiled wilderness, especially to our north in Canada, we want to be prepared if there are plumes of air from forest fires that invade Marquette similar to NYC/DC this past week!

We are still in the testing phases of this device. Once it appears to be reliable & accurate we may publish the AQI reading in the “Weather Conditions” section of the home page (CITY).

UPDATE 06/12/23 10:30 PM:

Air Quality readings are now available on our home page! I have included range information (0-500) for this reading and a couple others too. You can now click on any header in the Weather Conditions section and it will give you a “tooltip” explaining that measurement. I see this as a great way to educate visitors and enhance engagement with the site.

 

New Rain Calibration Active

You may have noticed that at times rainfall totals in the Almanac section or History page suddenly shift, usually downward. That’s because the automatic rain gauge runs a little wet. Oftentimes, I circle back and correct the amount with what I’ve measured in the manual gauge (~ 6′ away and 3′ lower).

Well, through the wonders of technology (a.k.a. Microsoft Excel), I was able to finally calculate the error and program a correction for it. Over the last 12″ of rainfall, it’s a pretty consistent 4-8% overage. It averages out to +6.5%. So I am subtracting that from realtime readings now. I’ll keep an eye on it to see if it changes over time.

For small events, it may not have any effect whatsoever. But in larger rain storms, it should allow for fewer corrections and, thus, less confusion.

Radar Maintenance Until 3 PM 7/1

The radar is down until approximately 3 PM on Wednesday July 1st for maintenance.

Be aware that starting Monday July 13th the radar will be down for approximately 2 weeks. Technicians will be swapping out the pedestal. See the NWS blog article for more information.

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