Page 1 of 1
Posted: Tue Dec 18, 2018 10:31 pm America/New_York
I recently started working on seadas. I am processing MSI sentinel data .I have successfully processed sentinel-2 data using l2gen command with ifile and ofile.But I need only Rayleigh corrected image.In previous posts I found , we can get only rayleigh corrected images by rho_nnn.I think this should be an intermediate file created during processing of l2gen command.
I am eager to learn the basic commands like
1.How to display our processed image by command
2.How to save images in our required formats like tiff,hdf or nc
3.How to retrieve only required parameters (like only rho_nnn)
Please guide to get some refernces to know these basic things
Posted: Wed Dec 19, 2018 9:06 am America/New_York
I suggest you have a look at some of the introductory videos that the SeaDAS
folks put together to get you started.https://seadas.gsfc.nasa.gov/tutorials/video_tutorials/
There is also a good collection of help pages available for the various SeaDAS
P.S. I believe you are looking for rhos_nnn.
Posted: Wed Dec 19, 2018 10:49 am America/New_York
Thank you norman.
Yes I want rho_nnn for sentinel-2 image.
will this command will work for rhos_nnn
l2gen ifile="" ofile ="xxxx.L2" product=rhos_nnn
Posted: Wed Dec 19, 2018 11:00 am America/New_York
Note the "s".
Posted: Wed Dec 19, 2018 3:16 pm America/New_York
need to set "l2prod=rhos_nnn" not product.
run l2gen on the command line without any options to get a list of the options available.
Posted: Thu Dec 20, 2018 5:45 am America/New_York
Thank you so much .It worked.
Now I am this assuming rhos_nnn are only rayleigh corrected .
I observed that F0 values below are not matching with F0 given in metadata.
Bnd Lam Fo Tau_r k_oz k_no2 t_co2 awhite aw bbw
0 442.000 187.338 2.366e-01 2.837e-03 5.072e-19 1.000e+00 0.000e+00 7.057e-03 2.187e-03
1 492.000 196.024 1.563e-01 2.592e-02 2.844e-19 1.000e+00 0.000e+00 2.111e-02 1.410e-03
2 559.000 182.410 9.115e-02 1.042e-01 8.920e-20 1.000e+00 0.000e+00 6.234e-02 8.149e-04
3 665.000 151.348 4.489e-02 5.033e-02 8.658e-21 1.000e+00 0.000e+00 4.177e-01 3.945e-04
4 704.000 142.593 3.559e-02 2.055e-02 3.752e-21 1.000e+00 0.000e+00 6.960e-01 3.112e-04
5 739.000 129.029 2.919e-02 1.096e-02 1.494e-21 1.000e+00 0.000e+00 2.672e+00 2.542e-04
6 780.000 117.556 2.353e-02 7.322e-03 4.277e-22 1.000e+00 0.000e+00 2.675e+00 2.038e-04
7 835.000 104.151 1.851e-02 3.559e-03 1.882e-22 1.000e+00 0.000e+00 3.513e+00 1.577e-04
8 864.000 95.478 1.554e-02 2.277e-03 3.049e-23 1.000e+00 0.000e+00 4.588e+00 1.335e-04
9 943.000 81.782 1.092e-02 7.461e-04 9.177e-26 1.000e+00 0.000e+00 2.211e+01 9.309e-05
10 1611.000 24.706 1.280e-03 0.000e+00 0.000e+00 1.000e+00 0.000e+00 7.557e+02 1.048e-05
11 2184.000 8.775 3.800e-04 0.000e+00 0.000e+00 1.000e+00 0.000e+00 2.282e+03 3.043e-06
but in metadata the values are :
means F0 In metadata is 10 times greater than this F0 .
..... and band10 is 1376 with F0 365.41 is not included in the list..
I did not understood these things .Please clarify these things
Posted: Thu Dec 20, 2018 8:14 am America/New_York
Units. The factor of 10 is because one set is in W/m^2/nm and the other mW/cm^2/um
The 1376nm band is the cirrus band, used to detect high cirrus clouds. It is not included as part of the standard atmospheric correction processing because, well, we can't be certain how high the cirrus clouds are - so can't make a reasonable adjustment to remove the Rayleigh component. There is a special output product for it, rho_cirrus - it is NOT Rayleigh corrected.
Posted: Thu Dec 20, 2018 11:32 am America/New_York
Thank you sean
Is rho-cirrus can also be obtained as l2prod=rho-cirrus????
What is the importance of this product .
Posted: Thu Dec 20, 2018 12:00 pm America/New_York
rho-cirrus, and yes you would add it to the l2prod list.
If you're interested in screening based on cirrus cloud detection, it might be interesting to use this product. We've not put much effort into exploiting it for ocean color processing. The band was intended for the cloud/water vapor processing (so the MODIS Atmospheres team uses it...)