modis_lakes and sf_lake_physics

[plantain]

I'm running downscaling 12 hour forecasts initialized from GFS data in areas including both the 'lakes district' in Finland and Lake Superior in the US.
I'm looking for guidance on best practices for properly resolving lake effects such as lake/'sea' breezes, in particular whether there are benefits to running sf_lake_physics for short forecasts like these, and also whether there is any reason to use modis_lakes over modis_15s if sf_lake_physics = 0.

 

[Ming Chen]

The lake scheme is used with actual lake points and lake depth derived from the WPS, and it also can be used with user defined lake points and lake depth in WRF (lake_min_elev and lakedepth_default). As for your question about using modis_lakes over modis_15s, modis_landuse_20class_15s_with_lakes includes inland lake points, which are distinguished from ocean points. In modis_landuse_20class_15s, inland lakes are simply taken as water points and treated the same as ocean points. For your case, if you want to run with sf_lake_physics option on, I believe the modis_landuse_20class_15s is a better option. However, if you run with the sf_lake_physics option off, then either datasets should be fine.

The lake scheme developments and evaluations can be found in

Subin et al. 2012: Improved lake model for climate simulations, J. Adv. Model. Earth Syst., 4, M02001. DOI:10.1029/2011MS000072;
Gu et al. 2013: Calibration and validation of lake surface temperature simulations with the coupled WRF-Lake model. Climatic Change, 1-13, 10.1007/s10584-013-0978-y

Without any results of the simulation, it is hard to tell what options are the best for your case. I would suggest you conduct a few sensitivity tests with and without the lake option, and verify the simulations against observations to determine what is the best option.

 

[plantain]

If modis_lakes is used, but sf_lake_physics is off, should/will lakes be treated the same as ocean points?

 

[Ming Chen]

Yes you are correct. All lake points will be treated as water points in WRF if the lake module is turned off.