Advice with settings for rhorc

[dcar1s0n]

First, thanks very much for developing and supporting this free tool.

I am trying to perform atmospheric correction of two Sentinel-2 tiles in a fjord system in Greenland. I would like to work with the Rayleigh-corrected reflectances. I am only able to get acolite to run when I set dsf_path_reflectance=fixed

I have also tried running the python beta version, but I get the following: Parameter rhorc_* not computed

I have attached my settings file

Can you offer any advice?

[quinten]

Hi Daniel

For obtaining only Rayleigh corrected reflectances using dsf_path_reflectance=fixed is your best bet!

Up until yesterday the Python beta version did not output rhorc_* at all for tiled processing (dsf_path_reflectance=tiled is the default setting for L/S2). This should have been resolved with the commits I did yesterday. However if you only want Rayleigh correction, "fixed" may be the better bet since the per pixel geometry is then used if available (Landsat Coll2 data, Sentinel-2 data), while "tiled" uses the subtile average geometry.

I have now also changed the parameters used in the Rayleigh correction a bit so you can switch between including/excluding air-water interface effects using sky_correction=True or False. ("sky_correction" is a bit of a misnomer and I should've called it "air_water_interface_correction" or something like that since it includes the sun glint spot)

A git pull should do the job. Hope this helps!

Looking forward to seeing your results for the Greenland fjords!

Quinten

[quinten]

Hi Daniel

I realised that you could probably also output the Rayleigh corrected reflectances by using a user defined aerosol optical thickness of 0.001. This would have the advantage of faster processing, since then there is no need to compute both rhos and rhorc:

Code: Select all

dsf_fixed_aot=0.001
dsf_path_reflectance=fixed
l2w_parameters=

The outputs would then be named "rhos" in the L2R file, with (practically) zero aerosol reflectances.

Quinten