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PostPosted: Sun May 25, 2014 6:01 am 
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Joined: Sun May 18, 2014 8:52 pm
Posts: 1
Hello administrator,
I would study on evapotranspiration on my country (Iran),
I have a few questions:

1- Which STASH codes can I use for evaporate?
2- How units of Evaporation (kg/m2/s) to mm / day have become?
I run Precis Model for 2070-2100, Evaporation data for this time is 1500 to 15000 mm/day,
for The study area is too high!!!!!!

Thanks a lot


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PostPosted: Mon May 26, 2014 2:31 pm 
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Joined: Thu Feb 06, 2014 12:29 pm
Posts: 118
Dear Rahele,

I have found the following guidance from an old email

Quote:
To calculate the evaporation from the soil, vegetation (via evaporation of water on the vegetation) and vegetation (via transpiration) you need STASH items 3296, 3297 and 3299 and to complete the full set of surface moisture fluxes we have a sublimation diagnostic, 3298.

3296 EVAPORATION RATE FROM SOIL SURFACE         kg m−2s−1 Mean Single
3297 EVAPORATION RATE FROM CANOPY               kg m−2s−1 Mean Single
3298 SUBLIMATION RATE AT SURFACE                kg m−2s−1 Mean Single
3299 TRANSPIRATION                              kg m−2s−1 Mean Single

Alternatively, the total surface moisture flux is given by stash item 3223 at the surface.

3223 SURFACE & BL MOISTURE FLUXES               kg m−2s−1 Mean MLB 5

3223 is defined throughout the boundary layer with the lowest level being the surface moisture flux.

Finally, 3312 is the potential evaporation rate of open water.


Does this help answer your first question?

To convert a file with units km/m2/sec (equivalent to millimetres per second), you need to multiply the values in the file by 86400 (the number of seconds in one day).

For example, let's say I have a file dmhaea.pat2aug.05216.pp which is runid dmhae, a.pa (Daily means), t2 (2092), aug (August), 05216 (Stash code for Total Precipitation Rate) and a pp file.

I can convert this file using the PRECIS analysis tool called ppexpr

Code:
ppexpr -x "a*86400" -o newfile.pp a=dmhaea.pat2aug.05216.pp


The output file newfile.pp will contain values in millimetres per day rather than SI unit millimetres per second.

If you want to convert all the daily mean files in one directory, use a Unix regular expression. e.g.

Code:
cd $ARCHIVEDIR/dmhae/05216
mkdir $HOME/OUTPUT
ppexpr -x "a*86400" -e $HOME/OUTPUT a=*a.pa*.pp


That will convert all daily mean files *a.pa*.pp to daily means in mm/day, outputting the new files to $HOME/OUTPUT

Hope this helps
Thanks
David


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