Auto calibration / CL question

I have a question about the auto calibration / CL system. From another thread:

What happens if all the known good data sources are at different elevations from my station?

This is actually one of the reasons that I got my own weather stations, all the weather services seem to get data from nearby airports and all of the nearby airports are either 1500 feet higher or 1500 feet lower than me. I’ve seen temperature differences as great as 10F between my location and those known good sources.

Right now, my temperature and humidity seem to be pretty good so however it’s being done, it seems to be working well for those.

My bigger concern will be with rain as amounts also seem to vary significantly between the surrounding stations. And I say will be, because we haven’t had any yet since I’ve installed my Sky and probably won’t for a few more weeks at a minimum.

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Hi @bpaauwe . Good questions. It’s essentially an algebra problem. Here’s the formula for calculating Sea Level Pressure:


If you know the Psl from surrounding data sources (including observations at various elevations normalized to Psl as well as hi-resolution forecasting) you can solve for Psta and automatically apply a daily calibration. Once applied, the raw data from your AIR sensor provides the Psta value for the calculation and the ongoing auto-cal system acts as quality control check.

The auto-calibration / CL system for rain accumulation has not yet been deployed as it’s quite a bit more involved than the other parameters…so don’t bother with comparisons yet. For rain, many sources are queried many times daily. It’s kinda like a guitar with a tuner: whereas the tuner can keep the guitar strings in tune but the guitar produces the sound, the auto-cal / CL system will listen and make sure the haptic sensor in your SKY is in tune, but your SKY is producing the data signals. Further, CL system will leverage applied machine learning over time to better understand performance under different conditions and train the tuning accordingly.

Pray for rain!


i had a related question about callibration right here Remote callibration basically asking if for example my air will report the temperature calibrated to the nearby airport, or will it give the real temperature, because I’m in town and one can expect the real temperature to be one or two degrees higher.

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Hi @sunny Your AIR will report the real temp from the location at which it is sited. Following the guitar analogy used above, the auto-cal system provides tuning but your AIR plays the actual notes. And, we will be using a range of data sources both observed and modeled, certainly not limited to your nearest airport.

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@WFmarketing provided a great explanation . . . and it is good to see the actual formula that is being used for sea-level pressure (Psl) calculation (with the very minor exception that gravitational acceleration does vary slightly depending on elevation).

I am pretty fortunate to be able to compare my station pressure readings with an actual mercury barometer (never mind the thought that a mercury barometer might have some adverse health effects - at a certain age, you don’t worry so much about that sort of threat). Station pressure in inches of Mercury measured by other types of instruments better be pretty darn close to inches of Mercury column in my barometer. And . . . I am very happy to say that the station pressures reported by my Air units are so close to my actual Mercury column measurements that they are within the error range of my ability to measure my Mercury column.

For that reason, when a station owner complains about a barometric pressure problem, my first thought is that they have a configuration problem affecting either ground elevation (hel) or height above ground (hag).

Can’t wait to see the rain calibrations kick in!



Besides airports and modeled data, what other sources of observed data is CL relying on?