Re: conversion

Hello Abdoulaye,

effectively all you need is to multiply by 86400, but in reality you are also
multiplying and dividing by 1000. You multiply by 1000 when you go from m to mm,
but divide by 1000 when you take density into consideration:

kg m-2 s-1 = (kg m-3) x (m/s)
So, to go from m/s to mm/day you multiply by 86400x1000
But to take out density (measured in kg m-3) you divide by 1000.

Hope this makes sense... Maybe there is a better way to explain it, but in any
case you know that in mm/day you are expecting values of precipitation rate that
span 0-20...
In the example below - precipitation rate in the NCEP-NCAR Reanalysis (which I
would not use for research - am only using for sake of comparison) is also in
kg/m2/s
http://iridl.ldeo.columbia.edu/expert/SOURCES/.NOAA/.NCEP-NCAR/.CDAS-1/.MONTHLY/.Diagnostic/.surface/.prate%5BT%5Daverage/86400/mul/prcp_0to500_colors/DATA/0/20/RANGE/X/Y/fig:/colors/thinnish/solid/coasts_gaz/:fig/
so I just multiplied by 86400, and am getting values in the expected range.

cheers, alessandra

--
Alessandra Giannini
IRI for Climate and Society - The Earth Institute at Columbia University
P.O. Box 1000, Palisades NY 10964-8000
phone/fax: +1 845 680-4473/4864 - email: alesall_at_iri.columbia.edu
Quoting Abdoulaye SARR <layesarr_at_ucad.sn>:
> dear ncl users,
> 
> (not a direct plotting issue)
> 
> I am plotting model precip and the unit is kgm-2s-1 and as I want 
> mm/day I am multiplying by 84600s. Is this ok or do I need to take into 
> account something else?
> Suggestion welcome.
> 
> Best regards
> 
> Abdoulaye
> 
> 
> ----------------------------------------------------------------
> Universite Cheikh Anta DIOP - DAKAR
> 
> 
> 
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