MODIS Level-2 data post-processing and order

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harshbardhan
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MODIS Level-2 data post-processing and order

by harshbardhan » Tue Jun 28, 2022 7:45 am America/New_York

Hi,
I am trying to regrid the MODIS_L2 10km Aerosol data from Swath to regular grid.

As suggested on hdfeos forum (http://hdfeos.org/zoo/LAADS_MOD_py.php), I am using pyresample (a geo-resample package in python) to do the same. Since the daily MODIS_L2 swath data comes in huge numbers (particularly in case of a decade of analysis), so post-processing during data order is another option to subset the SDS and ask for the Mosaic from multiple swath to single region of interest swath file.

But in doing so in post-processing the geolocation field (Geo-2D latitude & longitude as in Level 2 hdf files) get removed which adds an another level of challenge to determine the latitude and longitude of the hdf files. While the same post-processed .hdf files in panoply shows virtual lat lon in Data_Fields as 1D.

Is there any robust option to retain the same geolocation field as regular Level2 hdf files and ask for doing post-processing? or any other way to sub-set and mosaic the multiple swath files to single?

Thanks in anticipation!
Harsh

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Re: MODIS Level-2 data post-processing and order

by LAADS_UserServices_M » Tue Jun 28, 2022 9:58 am America/New_York

The LAADS post-processing during data order is probably the best option you have available. You can reproject your mosiac to Geographic grid using the "Reproject" option. You can find bounding coordinate in each files header metadata.
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ianashpole
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Re: MODIS Level-2 data post-processing and order

by ianashpole » Thu Dec 15, 2022 11:19 am America/New_York

Hi,

I am following up on this query, as I am undertaking a similar task to the OP. I want to analyse several years of L2 10km aerosol data (from MYDATML2/MODATML2 files) for a specified (large) region, and am interested by the LAADS mosaic and reproject post-processing options. However, there is a limit of 30 files per order, and this does not cover a single day even when restricted to files that only cover my region of interest (via the geographic search utility when ordering).

I am therefore wondering if there is a workaround to facilitate post-processing on a larger number of files; or whether the only LAADS solution is to submit a huge number of orders (which would be on the order of thousands for several years of data).

Note, I am also exploring the option of bulk-downloading swath files and processing them myself following python examples on the hdfeos forum (http://hdfeos.org/zoo/LAADS_MOD_py.php), but am encountering some issues with that too (specifically with mosaicing overwriting earlier swath data with later - an issue that I have raised on the forum there).

Thanks in advance for any help or guidance.

kmmrao
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Re: MODIS Level-2 data post-processing and order

by kmmrao » Mon Jan 16, 2023 2:04 pm America/New_York

Hi,
It's quite easy using python.
I have composed a python script for multiple days with global coverage.
My script is on github. Hope it would help you. The link to my github repository is https://github.com/kmmrao/Mosaicing-MODIS-Level-2-Global-AOD-and-Visualizing-/blob/main/MODIS%20L2%2010KM%20AOD%20Regridding%20Single%20File%20and%20plotting.ipynb

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