Water vapour, ozone and aerosol data from MERRA-2 datasets

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yang16
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Water vapour, ozone and aerosol data from MERRA-2 datasets

by yang16 » Tue May 04, 2021 10:16 pm America/New_York

Hello!

I want to use the total amount of water vapour and ozone and aerosol optical depth at 550 nm (AOT_550) data from the MERRA-2 datasets. The related variables are as bellow:
TO3: totoal column ozone
TQV: total precipitable water vapour
TOTEXTTAU: total aerosol extinction aot_550nm
TOTSCATAU: total aerosol scattering aot_550nm

But I wonder how to correspond these variables to the data I want?

Thank you in advance.
Kind regards,
Mengmeng.

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GES DISC - jimacker
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Re: Water vapour, ozone and aerosol data from MERRA-2 datasets

by GES DISC - jimacker » Thu May 06, 2021 3:36 pm America/New_York

Mengmeng,

Thank you for your query. Unfortunately, what you are seeking is not clear from the way your question is phrased. Do you want instructions on how to acquire these variables from our system for specific dates and locations? Or are you trying to compare these MERRA-2 variables to data variables with a different name?'

Please clarify and we will work to assist you as quickly as possible.

yang16
Posts: 17
Joined: Wed Mar 30, 2016 8:28 am America/New_York

Re: Water vapour, ozone and aerosol data from MERRA-2 datasets

by yang16 » Thu May 06, 2021 7:26 pm America/New_York

Hi jimacker,

Thank you very much for your reply. I am sorry for your confusion. Actually, I already got TO3, TQV, TOTEXTTAU, and TOTSCATAU data from the MERRA-2 datasets. But I was not sure how do these data correspond to the total amount of water vapour and ozone and AOT_550 which are the data I need?

Thank you in advance.
Kind regards,
Mengmeng.

GES DISC - jimacker
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Re: Water vapour, ozone and aerosol data from MERRA-2 datasets

by GES DISC - jimacker » Fri May 07, 2021 9:18 pm America/New_York

We'll check with our MERRA-2 data scientists at the GES DISC and also contact the MERRA-2 scientists to find out if we can provide some guidance for you on this question.

yang16
Posts: 17
Joined: Wed Mar 30, 2016 8:28 am America/New_York

Re: Water vapour, ozone and aerosol data from MERRA-2 datasets

by yang16 » Sat May 08, 2021 12:08 am America/New_York

Hi jimacker,

That's great. Thank you very much.

Kind regards,
Mengmeng.

GES DISC - jimacker
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Re: Water vapour, ozone and aerosol data from MERRA-2 datasets

by GES DISC - jimacker » Mon May 10, 2021 5:47 pm America/New_York

Hello,

Here is a partial answer, with links to resources that can provide more information.

First of all, it would be helpful to provide more information on how you wish to use the data.

We would like encourage you to read MERRA-2 File Specification (https://gmao.gsfc.nasa.gov/pubs/docs/Bosilovich785.pdf ) or send questions by email to merra-questions ( merra-questions@lists.nasa.gov).

TQV = total precipitable water vapor [kg m-2] (column total)
TO3 = total column ozone [Dobsons]
TOTEXTTAU = Total Aerosol Extinction AOT [550 nm]
TOTSCATAU = Total Aerosol Scattering AOT [550 nm]

TOTEXTTAU and TOTSCATAU are the optical effects at 550 nm of total aerosols, which is an indicator of total aerosols. We could not find the variables for total aerosol amount.

The total PM2.5, PM1.0, and PM10 may be derived by using variables in MERRA-2 aerosol data collections with the formula described in the GMAO MERRA-2 FAQs (https://gmao.gsfc.nasa.gov/reanalysis/MERRA-2/FAQ/). Please read the MERRA-2 File Specification (https://gmao.gsfc.nasa.gov/pubs/docs/Bosilovich785.pdf ) to find data collections that contain the aerosol variables indicated in the formula.

yang16
Posts: 17
Joined: Wed Mar 30, 2016 8:28 am America/New_York

Re: Water vapour, ozone and aerosol data from MERRA-2 datasets

by yang16 » Tue May 11, 2021 5:29 am America/New_York

Hi Jimacker,

Thank you very much for your info. I want the reanalysis data of AOT_550, total precipitable water vapor (in cm unit) and total ozone (in cm-atm) as input for a radiative transfer model for atmospheric correction.

In this sense, do you know which ozone product from the MERRA-2 datasets can I use?
In addition, I wonder how to convert the TQV data unit from kg m-2 to cm?

Thank you in advance.
Kind regards,
Mengmeng.

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