Generate look-up tables

[panyuwei1]

Hi , I'm recently learning the OSOAA model and I want to generate Rayleigh and aerosol look-up tables, when I loop the output with the runwavelengths function, but the output OSOAA_RESULTS seems to take up too much space, so I would like to ask you how to generate ayleigh and aerosol look-up tables with OSOAA, maybe I'm thinking wrong, hope to get your help, thanks!

[blafranc]

Hello, If you only want to simulate the Rayleigh and aerosols effects, you have to cancel the ocean scattering. This is a specific use case:

• Open the source code src / OSOAA_SOS_CORE.F
• Set the expert parameter EXPERT_MODE_FORCED_FSEA_NULL as « .TRUE. » : i.e : #define EXPERT_MODE_FORCED_FSEA_NULL .TRUE.
• Make a new compilation gen/Makefile.gfortran
• Set the seabed albedo to the value of zero (-SEA.BotType 1 -SEA.BotAlb 0.)
• Set the sea surface albedo to the value of zero, i.e. no foam (-SEA.SurfAlb 0.)

You need to implement a script to loop on the wavelengths, pressures, aerosol optical thicknesses and models, using OSOAA with a command line. An OSOAA result file is not big. But, I recommend you to use a given working directory and overwrite the result files for each simulation with, of course, an extraction of the normalized radiance for the wanted viewing directions between to OSOAA processes.

If you simulate many aerosol models and many wavelengths, it is the MIE directory that will take up the most space. I recommend you to define a MIE directory in common for all OSOAA simulations.

Hoping this answer will help you. Best regards

[panyuwei1]

Thank you very much for your answer. When I was using the runwavelengths function in pyosoaa, I set the solar zenith angle to 0~80° at 10° intervals and the relative azimuth angle to 0~180° at 5° intervals, which resulted in an Advanced and Standard output file under results in OSOAA_ROOT for each band and angle, so takes up all my ubuntu space. What happens if I use shell scripts to output the results, do I modify them directly in the .ksh file, e.g. -ANG.Thetas 0 10 20 30 ./ Thank you again for your advice and answers, I will follow your suggestions

[blafranc]

Hello,

The function pyosoaa is not part of the OSOAA package. I can not make recommendation about this tool.

But, I can suggest you to implement a python code to run OSOAA with loops. You simply need to write a command line and run it for each loop (i.e. each Solar zenith angle, each aerosol optical thickness, each wavelength, etc) and extract the wanted results from the Standard output file (or Advanced file if you need several relative azimut angles).

In the ksh script, each parameter (-Keyword) has only one associated value (-ANG.Thetas 0 10 20 30 is not allowed) You can loop on parameters in a ksh script, but it is easier to manage the loops and data extraction in a python code.

Best regards

[blafranc]

For questions related to the pyosoaa function, you can ask https://github.com/fnemina/pyOSOAA/issues

[panyuwei1]

Okay！thank you, your answers and suggestions were very helpful, thank you again for your patience!

[amsuhail]

Hi,

If I want to generate LUTs for rayleigh reflectance, I assume that I have to put aerosol optical thickness = 0. Similarly, if I want to generate LUTs for aerosol refectance, I should put rayleigh optical thickness = 0. If I put like this, will it account for rayleigh-aerosol multiple scattering interactions?

Regards, Suhail

[blafranc]

Hi,

If I want to generate LUTs for rayleigh reflectance, I assume that I have to put aerosol optical thickness = 0. Similarly, if I want to generate LUTs for aerosol refectance, I should put rayleigh optical thickness = 0. If I put like this, will it account for rayleigh-aerosol multiple scattering interactions?

Regards, Suhail

Hello, If you consider there is no aerosol (AOT = 0) or there is no Rayleigh scattering (MOT = 0), you will only consider the multiple scattering for the considered particles. That means:

• if AOT = 0 : multiple scattering only by molecules,
• if MOT = 0 : multiple scattering only by aerosols).

If you want to simulate radiative interactions between molecules and aerosols, you must define an atmospheric profile including aerosols and molecules. The multiple scattering interactions are then calculated by the RT code OSOAA.

I suggest you to open a devoted/personnal Issue for future questions, if any.

Best regards

Note: AOT = Aerosol Optical Thickness MOT = Molecular Optical Thickness

[amsuhail]

Thank you...