People have said that the error increases as you get further from the calibration elevation, which would make sense if it isn't trying to use temperature, which it probably should if you're high enough for the temperature to fall.
Problem 1: How should the watch know if it is using the correct temperature?
Let us assume that the ISA standard temperature is +3 °C at your altitude, and this is what the watch bases its calculations on. The real outdoor temperature that day is -5 °C at your location. However, you are wearing the watch on your wrist where it is heated by your body, so the watch measures a temperature of +18 °C.
In that situation, if the watch tries to use its temperature measurement for a more precise altitude calculation, it will make an error which is larger than it would by using the ISA standard temperature.
Problem 2: What should the watch do if the measured temperature changes?
Let us assume that your watch starts at a high temperature because you came from inside your house. During the run, the temperature of the watch drops. You run a course at constant altitude high above the sea, for example 2000 meter, and the ambient pressure is also constant.
If the watch should try to calculate a better temperature correction for the air density based on the measured temperature, this would mean that the calculated altitude would change, even though you are running at constant altitude. That is not desirable.
Beside all what you write here about the watch is heated by the body, maybe my watch has an individual problem, I mean a error.
Today running: 7degree celcius Ambient, I came from inside (12 degree ... yes, no heating here), the watch shows 27 degree. Then it drops to 14 degree, and slowly increase to 17degree. See the two pics attached.
I still think this offset is way to big. So I removed the watched and put it on a cold steel mesh table, so the cold 7 degree air could float all around my watch. After 15min, the temperature was still 16 degrees. When I put the watch back to my wrist, the temperature changed with 1min from 16 to 17, then 18C, and stay at this value.
So I think my temperature sensor is broken or has an offset + 10°.
Can I get some data from other users, if they are running in cold, and then remove the watch, what is the difference after 15min? ciq.forums.garmin.com/.../1288462.png
The watch temp shows 27° at beginning, then went to 16 degrees, but towards the end of my run (55min), it went up to 20 degree. Barometer was always same, 1020. Elevation was always correct.
After I sit down still outsite, after 2 min, the watch increased to 23° and the barometer changed to 130. (still on my wrist) So I checked the height, suddenly was 100m offset, shows 480m, instead of 380m. I removed the watch from my wrist, the temperature changed in 10min from 23 to 16 degree and stayed there. Barometer changed back to 120, and the elevation to the correct 380m. After I put the watch back on my wrist, the temp increased to 18 degree, baro and height kept stable.
Summary: I think offset of 3-5 degree because of body heat is ok, but my watch for sure has an offset or error with the sensor +10.
Anyone else has some data to compare the temp showing on the wrist and off the wrist compared to real values? Thanks
