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.
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.
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.
You might have noticed a couple new readings in the “Current Conditions” section of our home page. I’ve installed 2 new sensors on our main weather station, a Davis Vantage Pro2, to measure output from the Sun.
One sensor reads a narrow band of ultraviolet (UV) radiation. The 290 – 390 nm spectrum of the sun’s shortwave energy particularly affects human health. Readings are translated into a universal UV index (1 – 16 scale).
The other sensor measures broad spectrum solar radiation (a.k.a. “solar irradiance”, “solar insolation”) between 300 – 1100 nm. It’s output scale is 0 – 1800 Watts per meter squared (W/m2). This is useful for solar energy management & approximating cloud cover / ambient light. You may wonder “can’t I just look out a window?” If you are in Marquette, yes. If you are elsewhere, no.
Continue reading “Here Comes The Sun”
As noted in the about page, I regularly check our sensors to be sure they are within specifications. Over the last couple weeks I have been conducting tests.
Temperature was right on. That’s typical, as our sensor is pretty bulletproof. I have a platinum RTD digital thermometer that’s accurate to within 0.1° F (best to check on a cloudy, windy night to eliminate radiation as a factor). I also have a laboratory-grade aspirated psychrometer with a dry bulb thermometer that’s extremely accurate. It’s analog, so the biggest challenge is reading between the lines. But my tests show the station’s thermal sensor is within 0.5° during the day which is quite good. There’s also a backup sensor on site as well. At night or on cloudy/rainy days, the two sensors are normally within 0.2° F. During sunny days, height (7 ft vs 21 ft) and shielding differences (active vs passive ventilation) can frequently lead to 1° differences in either direction. 2-3° differences are not out of the question when it’s particularly calm and sunny.
Continue reading “Instrument Calibrations”