One thing that has me scratching my head as I look at the MADIS data quality graphs again - why does the dew point appear to be in pretty good shape despite the reported discrepancies in temperature? I would’ve thought the two would be relatively closely aligned. Is the humidity reading causing it to balance out?? Or am I missing something obvious … ?
I’m also seeing variation in data between Sky and Tempest.
Yesterday was sunny here. Under identical conditions at noon yesterday, Sky showed a UV of 3 while Tempest was 1.1.
I have no way of calibrating this. Station 25741.
How many clear days during the hour before and after solar noon have you had since installing the Tempest? IIRC, it takes 12 clear days to calibrate the light sensor and UV.
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Good question. I’d have to look back.
With snow slowly coming in, I think I’ll have to wait until Spring to allow for a snow-free top of Tempest 
Thanks for replying. This is my 4th Tempest - and it’s finally working. The others were defective. Let’s see how it holds through winter 
Chat at y’all soon.
If your SKY is calibrated then support could use it to get an initial calibration until the CL algorithm has enough reliable data to make finer adjustments.
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How can I know when there has been a barometer calibration??? And by how much it was changed?
My friend a few kilometers inland from my station has a Tempest mounted for 6 months. Tonight it jumped in pressure nearer to what it should be. But he did nothing and it has been there for 6 months. (Although it is possible that it fell down because I can not see it) I would really like to know some way of knowing when a calibration is changed. How can we know about changes in calibrations?
The API returns this data:
[1621758900,2.64,3.68,4.47,171,3,1012,15.8,94,0,0,0,0,0,0,0,2.71,1,0,null,null,0],[1621758960,1.61,3.03,4.07,177,3,1013.4,15.8,94,0,0,0,0,0,0,0,2.71,1,0,null,null,0]
Which I convert into my own required values:
{
“air_temperature_c”: “15.8”,
“battery_volts”: “2.71”,
“device_id”: “109191”,
“epoch”: 1621758900,
“illuminance_lux”: “0”,
“lightning_strike_average_distance_km”: “0”,
“lightning_strike_count”: “0”,
“local_day_rain_accumulation_final_rain_check_mm”: “None”,
“local_day_rain_accumulation_mm”: “0”,
“obs_date_time_local”: “2021-05-23 18:35:00”,
“obs_minute”: “35”,
“precipitation_analysis_type”: “0”,
“precipitation_type”: “0”,
“rain_accumulation_final_rain_check_mm”: “None”,
“rain_accumulation_mm”: “0”,
“relative_humidity”: “94”,
“report_interval_minutes”: “1”,
“solar_radiation_Wm2”: “0”,
“station_pressure_mb”: “1012”,
“uv_index”: “0”,
“wind_avg_knots”: “7.2”,
“wind_avg_knots_10_min”: “7.1”,
“wind_avg_knots_5_min”: “6.8”,
“wind_avg_knots_hour”: “7.8”,
“wind_dir_degrees”: “171”,
“wind_dir_gust_10_min”: “175”,
“wind_dir_gust_5_min”: “175”,
“wind_dir_gust_hour”: “174”,
“wind_gust_knots”: “8.7”,
“wind_gust_knots_10_min”: “11.1”,
“wind_gust_knots_5_min”: “9.6”,
“wind_gust_knots_hour”: “13.8”,
“wind_min_knots”: “5.1”,
“wind_sample_interval_seconds”: “3”
},
{
“air_temperature_c”: “15.8”,
“battery_volts”: “2.71”,
“device_id”: “109191”,
“epoch”: 1621758960,
“illuminance_lux”: “0”,
“lightning_strike_average_distance_km”: “0”,
“lightning_strike_count”: “0”,
“local_day_rain_accumulation_final_rain_check_mm”: “None”,
“local_day_rain_accumulation_mm”: “0”,
“obs_date_time_local”: “2021-05-23 18:36:00”,
“obs_minute”: “36”,
“precipitation_analysis_type”: “0”,
“precipitation_type”: “0”,
“rain_accumulation_final_rain_check_mm”: “None”,
“rain_accumulation_mm”: “0”,
“relative_humidity”: “94”,
“report_interval_minutes”: “1”,
“solar_radiation_Wm2”: “0”,
“station_pressure_mb”: “1013.4”,
“uv_index”: “0”,
“wind_avg_knots”: “5.9”,
“wind_avg_knots_10_min”: “7.0”,
“wind_avg_knots_5_min”: “5.9”,
“wind_avg_knots_hour”: “7.8”,
“wind_dir_degrees”: “177”,
“wind_dir_gust_10_min”: “175”,
“wind_dir_gust_5_min”: “177”,
“wind_dir_gust_hour”: “174”,
“wind_gust_knots”: “7.9”,
“wind_gust_knots_10_min”: “11.1”,
“wind_gust_knots_5_min”: “7.9”,
“wind_gust_knots_hour”: “13.8”,
“wind_min_knots”: “3.1”,
“wind_sample_interval_seconds”: “3”
},
This is a chart with a kink in the barometer pink line at my friends place ‘Charlestown’: (edit, the kink is to the right, click to open the image to see the kink)
And from my place without the kink:
cheers Ian
Hey Ian
I don’t have full history but I see at least 6 pressure calibrations since April 21th though the one from Mai 20th is more radical (guess applied a few hours ago)
Regarding having more insight, there is a request for that in the appropriate section. If you have a vote left
Other thing that can change this is changing your device hight, your friend didn’t update that btw ?
Thanks Eric,
And all of a sudden a couple of hours later my station has just done the same. His is a Tempest and mine is an Air:
Guess the routine is applying calibrations to all the park if needed (over 22k active stations) and it takes quite some time.
Question is, is the calibration ok ?
Over a year ago my Air seemed spot on and I had assumed that it no longer needed new calibrations. I assumed that I could use my data without changes to its calibration. This makes me realise that I have no knowledge of changes which causes issues with how I wish to use my pressure readings. I am trying to forecast local winds and any change to my barometer calibration destroys its value.
The reading is near to what it should be but might be worse than it was.
This accurate station is about 20km in the lower pressure direction from my station.
In the past I calculated the pressure gradient and determined how accurate it was but the issue is that I dont want it to keep changing, especially without any correction calibration factor that I can allow for.
Two years ago I suggested to mark in the graphs when a calibration has been applied.
(a little exclamation mark on the horizontal axis perhaps)
But I wish to run my systems automatically and I never look at the weatherflow graphs except for fault finding. It really needs to be included in the output of the API.
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I agree. I could also envision a ‘solution’ that applies the calibration gradually, as in over a period of 3 months or so. It even could adjust the required calibration weekly, if needed, but still apply it very, very slowly (over months). Basically it would keep it calibrated and never jump.
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Even a slow change is bad. Then I could get the impression that an El-Nino event or similar is occurring. And on a smaller scale it upsets my local area pressure gradient values which indicates how my sea breezes will develop. A constant pressure calibration is critical for so many reasons that I will now be purchasing another system.
True, but the slow change might be caused because your instrument slowly looses its accuracy. In which case it is better to slowly correct the calibration.
if you need such a precision, don’t even think about any electronic one as over time they will all drift. (Maybe if you spend a few thousand $ on a pro model and even those need calibration)
the only one I know that is correct (except parallax errors)
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I have good news. The fantastic Weatherflow support staff have replied to my support call to ask me if I would like the automatic calibrations on my Air and Tempest turned off. I will have the automatic calibrations turned off and will monitor it over time to check if it drifts.
This is a very satisfying response.
Cheers Ian
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Let us know how it does. For my two Tempests, I have the CL turned off just for humidity. Humidity sensor performs well without CL’s involvement. But when the sensor does start drifting, I’ll ask David to turn it back on. Or hopefully they will give us the direct control be then.
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Support turned off my barometer calibrations
quote:‘we’ve disabled future pressure calibrations for your stations.’
But today it jumped again.
There may be some other reason?
I replied to my support call to ask them what is happening.
cheers Ian
When you asked to stop CL, did you mention this particular station or just your account as this one is linked to someone else’s name.