[gradsusr] what is the unit of moisture convergence?

[Davide Sacchetti]

specific humidity is defined as ratio of water vapor mass (g) over air
mass (kg) (units: g/kg)
mixing ratio is almost the same: ratio of water vapor mass (g) over DRY
air mass (kg) (units: g/kg)

your divergence is like d(u*mixr)/dx, then has units of (m/s * g/kg)/m:
units should be g/kg*s-1

bye bye
Davide

On Thu, 2013-05-30 at 01:39 -0700, Mohsen Soltani wrote:
> Dear GrADS Users,
> 
> 
> I employed the following script to display the moisture convergence.
> But, I don't know what is the unit of the output! Please see the
> attached plot and let me know what's your opinion.
> 
> 
> ************************************************************************
> * rh    = Relative Humidity in % 
> * t     = Temp at *set level in degrees Kelvin
> * tc    = Temp in degrees C
> * td    = Dewpoint at *set level in degrees C
> * e     = Vapor pressure 
> * mixr  = Mixing ratio
> * u     = U-wind in m/s
> * v     = V-wind in m/s
> * mconv = moisture convergence/divergence. 
> 
> 
> 'tc = (t-273.16)'
> 'td = tc-((14.55+0.114*tc)*(1-0.01*rh) + pow((2.5
> +0.007*tc)*(1-0.01*rh),3) + (15.9+0.117*tc)*pow((1-0.01*rh),14))'
> 'vapr = 6.112*exp((17.67*td)/(td+243.5))'
> 'e = vapr*1.001+(lev-100)/900*0.0034'
> 'mixr = 0.62197*(e/(lev-e))*1000'
> 'mconv = (1)*hdivg(u*mixr,v*mixr)*1e4'
> 'd mconv'
> ********************************************************
> 
> 
> 
> 
> Thank you,
> Mohsen
> 
> 
> --
> some are weather-wise some are otherwise!
> --
> Best Wishes,                                        
> (Mr.) Mohsen Soltani
> Climatology Grad Student (M.Sc.),
> Faculty of Geography, University of Tehran, Tehran, Iran
> Tel: (+98) 9119772934
> e-mail: soltani.clima at gmail.com
> 
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-- 
--> Attenzione cambio indirizzo: davide.sacchetti at arpal.gov.it
--
Davide Sacchetti
Centro Funzionale Meteo Idrologico di Protezione Civile della Regione Liguria
ARPAL Unità Tecnica Complessa di livello Regionale
V.le Brigare Partigiane 2 16121 Genova (I)
tel: +39 010 6437535                    fax: +39 010 6437520
mail: davide.sacchetti at arpal.gov.it     web: www.meteoliguria.it