December 07, 2021, 01:18:44 PM
Dyatlov Pass Forum

Author Topic: The weather at the site of the accident - with hour accuracy  (Read 746 times)

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May 15, 2021, 04:57:07 AM
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Earthland


We can't go back in time in every sense of the phrase, but we can go back in time in some sense. And one such sense is that we can go back and see what the weather was like at the time and place. It's called reanalysis, which combines model data with observations from across the world into a globally complete and consistent dataset using the laws of physics. Reanalysis produces data that goes several decades back in time, providing an accurate description of the climate of the past.

Reanalysis is not some kind of magic, but is used quite heavily by scientists. It should not be confused with measurements, which are made at a specific point; reanalysis always shows only averaged values over some area. How accurate is it? Depends on the time, place and particular variable. Using reanalysis in my professional work has yielded very satisfactory results, but with Dyatlov incident, we are talking about a mountainous region in a desolate district in Soviet union - I don't know how much trustworthy meteorological data from this region is used for reanalysis. For checking the validity of data, I should find the measurements from the closest synoptic station, and then compare. I might succeed in doing this.

Anyway, my first attempts with the data can be accessed here:


https://heidotrofimov.github.io/

I did not detect anything unusual in this data by myself :) . Actually, in the sense of the weather, 1-2 February 1959 seems remarkably average.
« Last Edit: May 15, 2021, 11:08:16 AM by Earthland »
 

May 19, 2021, 04:54:57 AM
Reply #1
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sarapuk

Case-Files Achievement Recipient
We can't go back in time in every sense of the phrase, but we can go back in time in some sense. And one such sense is that we can go back and see what the weather was like at the time and place. It's called reanalysis, which combines model data with observations from across the world into a globally complete and consistent dataset using the laws of physics. Reanalysis produces data that goes several decades back in time, providing an accurate description of the climate of the past.

Reanalysis is not some kind of magic, but is used quite heavily by scientists. It should not be confused with measurements, which are made at a specific point; reanalysis always shows only averaged values over some area. How accurate is it? Depends on the time, place and particular variable. Using reanalysis in my professional work has yielded very satisfactory results, but with Dyatlov incident, we are talking about a mountainous region in a desolate district in Soviet union - I don't know how much trustworthy meteorological data from this region is used for reanalysis. For checking the validity of data, I should find the measurements from the closest synoptic station, and then compare. I might succeed in doing this.

Anyway, my first attempts with the data can be accessed here:


https://heidotrofimov.github.io/

I did not detect anything unusual in this data by myself :) . Actually, in the sense of the weather, 1-2 February 1959 seems remarkably average.

Its useful. But obviously no model will be able to say exactly what the weather was like at the location of the incident at that time. Even a few miles apart and the weather can be very different.
DB
 

May 22, 2021, 02:37:29 PM
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Manti


I would like to ask, does this model take topography into account? "at 2M" does this mean, 2 metres above sea level or 2 metres above ground? Given they were on the mountain, it's not very high but still weather can be significantly different
 

May 23, 2021, 09:35:52 AM
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Earthland


I would like to ask, does this model take topography into account? "at 2M" does this mean, 2 metres above sea level or 2 metres above ground? Given they were on the mountain, it's not very high but still weather can be significantly different

It does take it into account, and 2m means two meters above the ground.

But it is true ERA5 has different, more specific model for "Mountain tourism meteorological and snow indicators", but at the time, it's only for Europe.

Good news is that in this year better resolution general weather data should become available, with ~9 km accuracy. Still, we can not recreate the conditions exactly at the place of the tent.