Earthdata Forum

I have been able to extract the parameter data in the merra2 dataset, but I don't know how to use these parameters to synthesize some data, for example, I want to synthesize the data of sulfate aerosol or black carbon aerosol in a certain area, please ask if there is any calculation formula or reference document.

Hello.

If you can provide a more detailed description of what you are attempting to calculate, we may be able to advise you and provide contacts with the relevant MERRA-2 scientists and developers. Reading your post, I am not clear on what you mean by "synthesize".

Sorry, I am a beginner. I want to calculate the aerosol optical thickness (AOD) of a region. In addition to that, I want to calculate the regional distribution of black carbon aerosol, sand aerosol, organic carbon aerosol, sea salt aerosol and sulfate aerosol in this region. I see that there are many parameters in the merra2 dataset, how can I use these parameters to calculate them?

As you stated you are a beginner, I would recommend trying our Giovanni data system, https://giovanni.gsfc.nasa.gov/, which has all of the data variables for which you noted you want to calculate regional distributions. Giovanni makes this easy to do, as you can select a region and variable, and map the variables for that region. There are several different ways to average the data, as well, which can be further described after you familiarize yourself with the system.

If you wish to calculate total AOD from aerosol components, that will be more computationally complex. I would recommend first examining basic definitions of AOD, as well as the AOD products available in Giovanni (there are several). Comparisons of AOD distributions to the MERRA-2 aerosol component distributions may be a good way to proceed. Depending on where you are examining, it may be fairly obvious what the primary component that it responsible for most of the AOD is; for example, sand aerosol in desert dust storms, or black carbon aerosol in wildfire smoke.

GES DISC - jimacker wrote:
> As you stated you are a beginner, I would recommend trying our Giovanni
> data system, [url]https://giovanni.gsfc.nasa.gov/[/url], which has all of
> the data variables for which you noted you want to calculate regional
> distributions. Giovanni makes this easy to do, as you can select a region
> and variable, and map the variables for that region. There are several
> different ways to average the data, as well, which can be further described
> after you familiarize yourself with the system.
>
> If you wish to calculate total AOD from aerosol components, that will be
> more computationally complex. I would recommend first examining basic
> definitions of AOD, as well as the AOD products available in Giovanni
> (there are several). Comparisons of AOD distributions to the MERRA-2
> aerosol component distributions may be a good way to proceed. Depending on
> where you are examining, it may be fairly obvious what the primary
> component that it responsible for most of the AOD is; for example, sand
> aerosol in desert dust storms, or black carbon aerosol in wildfire smoke.

Hello,
when I click on the giovanni link, it just takes me back to this same forum.

I am sorry, I misconfigured the link. This is correct: https://giovanni.gsfc.nasa.gov

GES DISC - jimacker wrote:
> I am sorry, I misconfigured the link. This is correct:
> [url]https://giovanni.gsfc.nasa.gov[/url]

hello,
still does not work. when I click on it, it just goes to this forum.

That's very strange. When I click on the link, it provides a pop-up asking for permission to go to an external site, then when I say OK, it goes to Giovanni. Perhaps you have a pop-up blocker that is interfering with the pop-up?

You can copy https://giovanni.gsfc.nasa.gov into your browser search window, and then go. I did not use the link button in my editor to create a link, yet the Forum is showing it as a link; perhaps this will work now.

Alternatively, try https://www.google.com/search?q=NASA+Giovanni and then click on the top link found with this search.

THANK YOU

GES DISC - jimacker wrote:
> That's very strange. When I click on the link, it provides a pop-up asking
> for permission to go to an external site, then when I say OK, it goes to
> Giovanni. Perhaps you have a pop-up blocker that is interfering with the
> pop-up?
>
> You can copy [b]https://giovanni.gsfc.nasa.gov[/b] into your browser search
> window, and then go. I did not use the link button in my editor to create a
> link, yet the Forum is showing it as a link; perhaps this will work now.
>
> Alternatively, try [url]https://www.google.com/search?q=NASA+Giovanni[/url]
> and then click on the top link found with this search.

hello,
I don't have pop-up blocker. must have been a problem with the forum software that day. now it is behaving like you described, I see the pop up about the external link.