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MCD19A2 AOD data preprocessing

Posted: Wed Dec 13, 2023 4:01 am America/New_York
by afnanullah279
I have few question regarding the AOD product (MCD19A2). I have downloaded the AOD product by applying post processing like sds=optical_depth_550, QA. should I have to select the AOD uncertainty as there it is mentioned that "AOD uncertainty based on blue-band surface brightness (reflectance)"? as my primary focus is on 550. secondly I have selected my area of interest (Lat, Long in Geo Info) but the images have the also the area outside of AOI (have extra tiles), how should I sort out this issue? Should I have to clip through (ENVI or other software)? How will I preprocess/Prepare these images in order to use it as a proxy for PM2.5 prediction using deep learning algorithms? can someone share the manual of process or guide accordingly? If someone specifically guide about preprocessing through, I'll be thankful.

Re: MCD19A2 AOD data preprocessing

Posted: Wed Dec 13, 2023 10:07 am America/New_York
by LP DAAC - lien
Hello,
Unfortunately,because of the multi dimensions of the MCD19A2 files our AppEEARS pre-processing tool does not support this as it does most all other MODIS products, you will need to download the data and clip it with your GIS software. The rest of your question we are in contact with the developer to get their input also. We will let you know when we find out more.
Thanks,
Brett

Re: MCD19A2 AOD data preprocessing

Posted: Tue Jan 09, 2024 3:47 pm America/New_York
by LP DAAC - lien
Hi afnanullah279
Looked into this a bit: Optical_Depth_055 refers to Green band aerosol optical depth, according to the user guide the description for AOD uncertainty states: AOD uncertainty: This parameter is evaluated based on the Blue-band B3 surface
brightness (reflectance) only, and thus gives only a general indication of possible increase
of error over brighter surfaces.

I believe you should only need the QA and not the AOD uncertainty since you are interested in the green band optical depth (Optical_Depth_055).

Unfortunately because of the complexity that the extra dimensions bring data will need to be subsetted after the tiles are downloaded.
We do have the LDOPE tools available that can help you unpack the QA bits, specifically the unpack_sds_bits.exe. You may also find the create_mas.exe usefull also: https://lpdaac.usgs.gov/tools/ldope/
Thanks,
Brett

Re: MCD19A2 AOD data preprocessing

Posted: Wed Feb 21, 2024 2:16 pm America/New_York
by afnanullah279
Thank you for your kind clarification. I have few other queries related to my question.
How will I use QA values align with Optical_Depth_550 as an input feature to the model?
How should I download AOD values in a csv for ROI or for a specific area pixel?
how should I apply scale factor (0.001) during preprocessing of AOD product in ArcMap?

Re: MCD19A2 AOD data preprocessing

Posted: Tue Feb 27, 2024 11:57 am America/New_York
by LP DAAC - lien
Hello,
I am really not sure on how you get get a csv file for AOD. Because of the multiple dimensions of the file, this product is not available in our AppEEARS tool. I am not sure if ArcMap can do that or not. You may have to check with the software documentation for many of these questions: https://www.esri.com/en-us/arcgis/products/arcgis-desktop/resources

Perhaps, someone from the user community who has used ArcMap specifically for this type of projects can give some ideas.
Thanks,
LPDAAC