Author Topic: (X-Post) Help me understand 'MADIS Analysis' for station barometric readings  (Read 960 times)

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Offline Dechief

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    • Sapphire Pointe (DW4892)
(Cross-posted on the CWOP forum)
I am at 6480 feet using a Davis Pro2 weather station and Weatherlink software.  I have been a CWOP 'member' for 10+ years and I consistently get this error on the CWOP page for the barometer from my station - but only now decided to dig into this deeper for find out why:
"The standard deviation of your readings is higher than expected. This can be caused by a broken sensor that always reports the same value. It can be caused by a faulty sensor that sometimes reports values way out of range (such as 0). Check that your sensor is operating correctly. Your station is at a high elevation and you are using Weatherlink. The pressure reduction algorithm used in this software does not produce the results required for CWOP. This gives problems when the temperature changes and makes it impossible to get consistent calibration."
After doing research on how Davis wants my station calibrated (i.e. using a nearby sea-level barometer), I've done so, using the NWS data from the Centennial CO airport (KAPA).  I'll note the airport is about 1,000 ft lower and 10 miles distance from my station.  After doing this calibration, I did 'spot checks' and found my station was almost always within 2 mb of the NWS data from KAPA and then I did a more thorough analysis over a week-ish time, using Excel (I've attached screenshots of my analysis your review/reference - since I can't attach the actual Excel spreadsheet).
What I see is a very accurate station barometer, closely matching the readings from the NWS (regarding both sea-level and altimeter-based barometric readings).
Please help me understand what I am missing and why the above error continually pops up on CWOP...
Thanks!
BTW - I've also attached a screenshot of what I see for my station's barometer analysis on CWOP.