New TOMS/OMI ozone location?

Use this Forum to find information on, or ask a question about, NASA Earth Science data.
Post Reply
earthengine_urs
Posts: 71
Joined: Mon Jan 27, 2020 10:36 am America/New_York
Answers: 0
Has thanked: 3 times
Been thanked: 1 time

New TOMS/OMI ozone location?

by earthengine_urs » Thu May 18, 2023 12:21 am America/New_York

Hi,

We used to download TOMS/OMI ozone data from https://acd-ext.gsfc.nasa.gov/anonftp/toms/omi/data/ozone/Y2023/, but that directory stopped updating on May 2

I suspect the new data location is https://acdisc.gesdisc.eosdis.nasa.gov/data/Aura_OMI_Level3/OMTO3d.003/ (found via https://disc.gsfc.nasa.gov/datasets/OMTO3d_003/summary) - could someone confirm this or direct me to the right location?

Thanks,
Simon

Tags:

earthengine_urs
Posts: 71
Joined: Mon Jan 27, 2020 10:36 am America/New_York
Answers: 0
Has thanked: 3 times
Been thanked: 1 time

Re: New TOMS/OMI ozone location?

by earthengine_urs » Wed May 24, 2023 2:20 pm America/New_York

I'm advised that the text ozone product was unofficial and it's better to use something listed CMR.

For OMI I see two level3 products: 0.25-degree https://disc.gsfc.nasa.gov/datasets/OMTO3e_003/summary and 1-degree https://disc.gsfc.nasa.gov/datasets/OMTO3d_003/summary

Are there any downsides to using the 0.25-degree product?

jejohns1
Posts: 2
Joined: Thu May 25, 2023 12:52 pm America/New_York
Answers: 0

Re: New TOMS/OMI ozone location?

by jejohns1 » Thu May 25, 2023 1:07 pm America/New_York

The host machine acd-ext.gsfc.nasa.gov belonged to the Atmospheric Chemistry and Dynamics Lab, NASA/GSFC code 614. These data are in an ASCII format that goes back to the old TOMS days.

The Ozone and Air Quality group at NASA/GSFC now hosts these same files at https://ozoneaq.gsfc.nasa.gov/. Select the OMI - Aura: Global Ozone Data from the Data Download link.

The GES DISC (where I work) archives and distributes the OMI/Aura data as well, but these are in an HDF-EOS5 file format (which can also be opened using netCDF tools/software). Our homepage is https://disc.gsfc.nasa.gov. The links you list are our archive location of the data files, and the dataset landing page respectively. But note the files are not the ASCII formatted files you were using before, they are in HDF-EOS5.

earthengine_urs
Posts: 71
Joined: Mon Jan 27, 2020 10:36 am America/New_York
Answers: 0
Has thanked: 3 times
Been thanked: 1 time

Re: New TOMS/OMI ozone location?

by earthengine_urs » Fri May 26, 2023 12:51 am America/New_York

Thank you, @jejohns1!

I see that files at https://acd-ext.gsfc.nasa.gov/anonftp/toms/omi/data/ozone/Y2023/ are back too!

What would you would be the best OMI ozone dataset to be ingested into Earth Engine? We don't mind switching to reading HDF5 files if the data there are in some sense better.

jejohns1
Posts: 2
Joined: Thu May 25, 2023 12:52 pm America/New_York
Answers: 0

Re: New TOMS/OMI ozone location?

by jejohns1 » Fri May 26, 2023 10:16 am America/New_York

Since the GES DISC is the official archive for OMI, we are required to have the OMI data available to the public. Thus it might make sense for you to get the data through our archive. We have both the 1x1 degree L3 OMTO3d, 'd' is average of good L2 pixels (which was what you were getting from the acd-ext site), as well as the higher resolution 0.25x0.25 degree L3 OMTO3e product data, 'e' is best L2 pixel. If you get the data from GES DISC you will have to adjust to using HDF-EOS5 files.

Post Reply