Forum

Hi, I can't speak for FLDAS products. However, MERRA-2 is a well documented atmospheric reanalysis. Please see the GMAO documentation page, especially the Gelaro et al (2017) article for the project overview. https://gmao.gsfc.nasa.gov/gmao-products/merra-2/documentation_merra-2/ Near surface wind s...

POWER does just mirror the MERRA-2 data, so the units and definition should be the same as MERRA-2. The depth of the root zone is 0-1m. Thank you for calling out this difference in the definitions, POWER is double checking their other parameters as well. There is a MERRA-2 land constants file availa...

Hi, I think you are asking how to compute RH from the meteorology that is available. My suggestion would be to use the specific humidity to compute vapor pressure (e). Use the temperature to compute saturated vapor pressure (esat). The RH is e/esat*100 You are on to the formulations in your message....

To be specific in the unit analysis: kg/m2/s - Kilograms of water falling over an area in a second divide this by 1000 kg/m3, the density of water to get m/s multiply this by 1000 mm/m to get mm of water per second Then multiply by 3600 s/hr for mm/hr (or you can call that an accumulation of mm in a...

It could be, if say there are clouds building to block the shortwave, or cold air outbreak that leads to a drop in the skin temperature. The thin diurnally sensitive layer in MERRA-2 ocean would react to the atmosphere forcing above. But also, to be precise, if you only want ocean surface data, you ...

Hi, The vertical integration is done at the model's native terrain following coordinate, not the pressure level interpolations. So, cp x Tv(x,y,sigma) x V(x,y,sigma) x DELP(x,y,sigma) , then vertically integrate sigma 0.0 -1.0, the full atmospheric column. The time averaging is done from the model t...

This is relative to the models coordinate system and the vector components of the wind. If you compare VLML with TAUY, you will find them positively correlated. The meridional component (V wind) is positive to the north, and the TAUY is also positive for positive V near the surface. It comes down to...

TAUY is defined as the northward stress in the File Specification Document, So TAUY is positive northward. You can find the File Specification Document, and many other useful documents here: https://gmao.gsfc.nasa.gov/reanalysis/MERRA-2/docs/

Thanks for your interest in MERRA-2. The MERRA-2 system (actually all GMAO systems) do not extrapolate profiles to where P > Ps, except a few quantities for thickness calculations. So yes, it is implicit.

The tavg data is centered on the reporting time and average of all time steps within the time window, and instantaneous is the data of the time step at the reporting time. It's probably not surprising that they correlate very high. The environment would need to change rapidly within an hour at many ...