[RegCNET] QUERIES ABOUT LATENT HEAT FLUX IN REGCM4

[Graziano Giuliani]

On 01/02/2013 11:47 AM, Suman Maity wrote:
> Respected
> Sir
> This is Suman Maity from IIT KHARAGPUR, India.I have the following queries:
> 1) As you know, there is no variable for Latent Heat Flux in the Surface
> Model output in RegCM4. How to calculate this?
> 2) There is no variable for Evaporation.One variable is written as
> Evapotranspiration. Could I use this for calculation taking as evaporation?
>
> I have searched and previously in regcnet, you have written,
>
> *Latent Heat  =  evporation * 2.51040e6     (if Tas > 0C)
>               =  evporation * 2.844e6       (if Tas <= 0C)
>
> Precisely, to convert to unit of W/m**2
>
> Latent Heat  =  evporation * 2.51040e6/86400    (if Tas > 0C)
>
>               =  evporation * 2.844e6/86400      (if Tas <= 0C)
> *
>
> But what is "Tas"? It stands for what? Also from where I will get
> evaporation?
> Please reply and if it is possible forward me any document for the whole
> matters.It's Urgent.
[...]

Tas is temperature of the atmosphere at surface, in the 4.3.5 the naming is 
following now this convention. Was previously t2m.

For the above formulas, the evaporation is in the SRF file the evspsbl variable.
Now the units are in kg m-2 s-1, so you must remove the 86400 factor.

The other constants are vapour and snow latent heats, in Joules kg-1


-- 
Graziano Giuliani - Earth System Physics Section
The Abdus Salam International Centre for Theoretical Physics
Strada Costiera, 11 - I - 34151 Trieste Italy