L1B files : Binning and format

Use this Forum to find information on, or ask a question about, NASA Earth Science data.
Post Reply
madjidh
Posts: 35
Joined: Wed Feb 27, 2019 10:05 am America/New_York

L1B files : Binning and format

by madjidh » Tue May 12, 2020 10:50 am America/New_York

Hello,

I have two questions :
1) Is there a way to bin L1B files (spatially / temporally) ? I would like to create daily MODISA files in L1B format.

2) Is there a way to convert the L1B file into netCDF ? Just to read it later with Matlab / Python.

Regards

Tags:

OB WebDev - norman
Subject Matter Expert
Subject Matter Expert
Posts: 142
Joined: Tue Feb 09, 2021 8:19 am America/New_York

L1B files : Binning and format

by OB WebDev - norman » Tue May 12, 2020 3:10 pm America/New_York

Since level-1 refers to the storage of radiometer data in sensor-view
coordinates (i.e. scan-line and pixel), it is not possible (by definition) to
combine individual scenes into a daily level-1 file.

You can, however, bin individual scenes and combine them into a
daily level-3 format.

For most of our products, we do not archive L1B, so our software that generates
L1B still produces HDF4 instead of the NetCDF4 that we now store our archive
products in.  I imagine that there are Matlab or Python utilities that read HDF4.

Regards,
Norman

OB.DAAC - SeanBailey
User Services
User Services
Posts: 1279
Joined: Wed Sep 18, 2019 6:15 pm America/New_York
Answers: 1

L1B files : Binning and format

by OB.DAAC - SeanBailey » Tue May 12, 2020 3:35 pm America/New_York

If your purpose is to have a gridded TOA dataset, you could use l2gen to output Lt, which can then be binned/mapped.  As Norman points out, it will no longer be "L1B", but L3.
Here's how it can be done:


l2gen ifile=<MODIS L1B> geofile=<MODIS GEO> ofile=<L2 filename> atmocor=0 gain=[1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0] l2prod=Lt_nnn
l2bin ifile=<L2_files.txt> ofile=<Daily L3b> flaguse=ATMFAIL
l3mpagen ifile=<Daily L3b> ofile=<Daily L3m>


The output of the l2gen example above would be a reasonably equivalent  netCDF4 version of the L1B that could easily be read by tools that read netCDF.

Sean

madjidh
Posts: 35
Joined: Wed Feb 27, 2019 10:05 am America/New_York

L1B files : Binning and format

by madjidh » Tue May 12, 2020 6:34 pm America/New_York

Wonderful I will try it, thanks

Post Reply