evaporation in CAM5?

[HBzheng]

Hi,
I want to know if there is an evaporation variable (in m/s) in the CAM5 historical output file? If it doesn't exist, how can I calculate the evaporation variable?

Plotting zonally-averaged precipitation minus evaporation

This issue has been discussed before, but I am not sure where this formula comes from.
I hope someone can help me solve this problem

 

[islas]

You can either use the surface water flux (QFLX) or the latent heat flux (LHFLX). If you use the latent heat flux you'd need to devide by the latent heat of vaporization (2.45e6 J/kg). Whichever way you do it, if you have the surface water flux in kg/m2/s and precipitation (PRECT) in m/s then to get P-E in mm/day you multply PRECT by 1000 (number of mm in a m) and 86400 (number of seconds in a day) and you would multiply QFLX by 1000 (number of mm in a m), divide by 1000 (density of water) (these to things cancel) and multiply by 86400 (number of seconds in a day). That's where the following formula from the other posting comes from

E - P = QFLX * 86400 - (PRECT)*86400*1000

If you don't have PRECT you can sum PRECC and PRECL

 

[HBzheng]

You can either use the surface water flux (QFLX) or the latent heat flux (LHFLX). If you use the latent heat flux you'd need to devide by the latent heat of vaporization (2.45e6 J/kg). Whichever way you do it, if you have the surface water flux in kg/m2/s and precipitation (PRECT) in m/s then to get P-E in mm/day you multply PRECT by 1000 (number of mm in a m) and 86400 (number of seconds in a day) and you would multiply QFLX by 1000 (number of mm in a m), divide by 1000 (density of water) (these to things cancel) and multiply by 86400 (number of seconds in a day). That's where the following formula from the other posting comes from

E - P = QFLX * 86400 - (PRECT)*86400*1000

If you don't have PRECT you can sum PRECC and PRECL

Hi islas,
Thanks for your fast and accurate reply, it is very useful.