Questions about downloading hydrotable files

[liu xuan]

Hi,

I want to use rttov_scatt to simulate radiation in cloud areas.The sensor I simulated is AMSR2.But I encountered some problems with downloading the hydrotable files.I found it on the RTTOV13 coefficient file download page on the official website（https://nwp-saf.eumetsat.int/site/software/rttov/download/coefficients/coefficient-download/）.I found it under the title：MW optical depth coefs and RTTOV-SCATT optical properties.But when I click to download it something doesn’t seem right.I really hope you can help me solve this problem.
(hydrotable_gcom-w_amsr2.dat)

Best wishes,

Xuan

[James Hocking]

Hi Xuan,

When you say “something doesn’t seem right”, could you say what the problem is specifically? Do you get an error? Does the file seem to be corrupt?

The direct link to download the AMSR2 hydrotable is:
https://nwp-saf.eumetsat.int/downloads/rtcoef_rttov13/hydrotable/hydrotable_gcom-w_amsr2.dat.bz2

Does this link work for you?

Best wishes,
James

[liu xuan]

Hi James,

I can open this link. So do I need to copy the content from this link?

Thanks,
Xuan

[James Hocking]

Hi Xuan,

The link is to the hydrotable file: click on the link, and download the file.

You will need to unzip it:

$ bunzip2 hydrotable_gcom-w_amsr2.dat.bz2

Then you can use the resulting file hydrotable_gcom-w_amsr2.dat with RTTOV-SCATT.

Best wishes,
James

[liu xuan]

Hi James,

Thank you very much for your help. I have successfully gotten hydrotable_gcom-w_amsr2.dat.But I encountered a new problem.The profile I entered includes cloud liquid water, cloud ice water and rain, but not snow and graupel.I set the value of both snow and graupel to zero.I want to know if there is anything that needs to be modified in hydrotable_gcom-w_amsr2.dat.I very much hope to get your reply.

Best wishes,
Xuan

[James Hocking]

Hi Xuan,

There is no problem to set any hydrometeor concentration to zero: this simply means that particular hydrometeor will not appear in the simulation. You do not need to edit the hydrotable file at all.

Best wishes,
James

[liu xuan]

Hi James,

Thank you very much for your help. I can simulate microwave radiation successfully. But according to my needs, I need to loop through the simulation until the simulated brightness temperature value is within the appropriate range. My Fortran program has been written and it shows that the compilation was successful. But after I ran it, the results showed that this cycle was not performed. I would like to know if this circular process is possible?

Thanks,
Xuan

[James Hocking]

Hi Xuan,

I don’t quite understand what you are trying to do, but it sounds like you need to manange the looping in your code that calls RTTOV. This is certainly possible, but that is something you will have to implement. You can create a loop around your call to rttov_scatt, modify the inputs in each iteration of the loop as required, and exit the loop when your criteria are met.

I hope that helps.

Best wishes,
James

[liu xuan]

Hi James,

I truly appreciate your help in resolving the problem.I wish you good health and success in your work. Please forgive my bad English.

Best wishes,
Xuan

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