<p>I would like to calculate dew point values at different pressure levels from the ERA5 data set. Is this possible and if so, how exactly can it be done? I have found an approximate formula that use temperature and relative humidity, but is this going to be scientifically sound? The formula is: Tdew = (237.3<em>X)/(17.269-X), where X=ln(Rh/100)+((17.269</em>Tair)/(237.3+Tair)).</p>

CC BY-SA 4.0
2023-03-01T02:45:51.093Z
Your formula looks a little different than the one at (How can temperature be calculated given relative humidity and dew point?)[https://earthscience.stackexchange.com/questions/14899/how-can-temperature-be-calculated-given-relative-humidity-and-dew-point]... but as far as I know calculating the Td from the RH and T is straightforward and scientific... the question is how precise are the ERA values vs how precise you are desiring.  ERA model estimates from whatever observations existed... if you aren't desiring an excess correctness, it should work. If you need extreme precision, real doubtful
JeopardyTempest
CC BY-SA 4.0
2023-03-01T03:37:19.240Z
@JeopardyTempest thanks! I'm not looking for extreme precision.
John Smith
CC BY-SA 4.0
2023-03-01T05:25:52.003Z
I would imagine dewpoints could regularly be off by a few degrees Celsius at many levels, even more as you go back further into eras with less balloon launches/satellite/ACARS, or look at more remote areas.  If that's workable, then I'd think you'll get worthwhile values typically.
JeopardyTempest
<meteorology><atmosphere><reanalysis><era>
Is it possible to calculate dew point at pressure levels from ERA5 data?
John Smith
# Is it possible to calculate dew point at pressure levels from ERA5 data?

(Asked by: username_0 on 2023-03-01)

I would like to calculate dew point values at different pressure levels from the ERA5 data set. Is this possible and if so, how exactly can it be done? I have found an approximate formula that use temperature and relative humidity, but is this going to be scientifically sound? The formula is: Tdew = (237.3*X)/(17.269-X), where X=ln(Rh/100)+((17.269*Tair)/(237.3+Tair)).

**Tags:** meteorology, atmosphere, reanalysis, era

> **Comments:**
> **username_1**: Your formula looks a little different than the one at (How can temperature be calculated given relative humidity and dew point?)[https://earthscience.stackexchange.com/questions/14899/how-can-temperature-be-calculated-given-relative-humidity-and-dew-point]... but as far as I know calculating the Td from the RH and T is straightforward and scientific... the question is how precise are the ERA values vs how precise you are desiring.  ERA model estimates from whatever observations existed... if you aren't desiring an excess correctness, it should work. If you need extreme precision, real doubtful  
> **username_0**: @username_1 thanks! I'm not looking for extreme precision.  
> **username_1**: I would imagine dewpoints could regularly be off by a few degrees Celsius at many levels, even more as you go back further into eras with less balloon launches/satellite/ACARS, or look at more remote areas.  If that's workable, then I'd think you'll get worthwhile values typically.  

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## 0 answers

