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tiwapravash / MCD19A2_MAIAC_AOD_Processing

This project processes MODIS (Moderate Resolution Imaging Spectroradiometer) Aerosol Optical Depth (AOD) data from the MCD19A2 product and creates a NetCDF file containing daily averaged AOD values. The script filters the data based on quality assurance flags, calculates daily averages, and stores the results in a structured NetCDF file.
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Could you please provide the complete code for this part? #1

Open zebiu opened 1 month ago

zebiu commented 1 month ago

Dear Author,

I hope this message finds you well.

I noticed that in the code provided, the section for extracting the date appears to be missing. Could you please provide the complete code for this part?

Thank you very much for your assistance.

Best regards,

zhang

tiwapravash commented 1 month ago

I will revise the code, thank you for bringing it into my attention!!! I will revise the code, this weekend

zebiu commented 1 month ago

While reading your code, I have some questions about the AOD_QA selection in it. May I ask what reference or criteria you based your AOD_QA selection on? Or what is the specific basis for the selection of AOD_QA in your code?

tiwapravash commented 1 month ago

The MAIAC AOD QA_flags were following the AOD QA definition for MCD19A2 (16 bit integer) present in https://lpdaac.usgs.gov/documents/110/MCD19_User_Guide_V6.pdf.The best QA flags if interpreted will be the 4 following 16 bit combinations : 0000000000000001 0000000000001001 0010000000000001 0010000000001001 As you read from right to left 

the First three bits (0-2) are for cloud mask (in all the cases its 001: clear )

The next 2 bits (3-4) are for Land/water/snow-ice mask which is either chosen as (00 or 01 : land/water)

Then next three bits (5-7) are for Adjacency mask where we choose 000 for all cases : Normal condition/clear

The next four bits (8-11) we chose only the best quality of AOD QA which is 0000

1 bit for Glint mask (12） we choose NO GLINT only

2 bits for Type of Aerosol model (13-14) where we choose either 00 or 01 as I am working on Black carbon (BC) and biomass burning do either background model or smoke model)

Final is reserved (NOT USED)

    ------------------ Original ------------------ From: "WRF is harder than a piano."; Date: 2024年8月5日(星期一) 下午5:15 To: "tiwapravash/MCD19A2_MAIAC_AOD_Processing"; Cc: "Pravash Tiwari"; "Comment"; Subject: Re: [tiwapravash/MCD19A2_MAIAC_AOD_Processing] Could you please provide the complete code for this part? (Issue #1)

 

While reading your code, I have some questions about the AOD_QA selection in it. May I ask what reference or criteria you based your AOD_QA selection on? Or what is the specific basis for the selection of AOD_QA in your code?

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tiwapravash commented 1 month ago

In summary THE AOD QA selection were based on AODQA Definition for MCD19A2 (16 bit integer) Section 4.4 page 13 of the MCD19 Data User guide : https://lpdaac.usgs.gov/documents/110/MCD19_User_Guide_V6.pdf The four set of 16 bit integer that are assumed to be the conditions that represent pixel quality is best is based on these the only changes are on Land/Ocean/Snow/Ice Mask where we choose either land or water Another change is on the 13-14 Aerosol model bit, where, I choose, Background model/Smoke model (as I am working on BC) Hope this helps Best Pravash Tiwari