Ozone Monitoring Instrument (OMI)
The Ozone Monitoring Instrument (OMI) aboard NASA's Aura satellite (launched in 2004) measures ozone from Earth's surface to top-of-atmosphere. OMI also measures sulfur dioxide (SO2), aerosols, and cloud top pressure. Near real-time (NRT) OMI data are available through LANCE generally within 100 to 165 minutes after a satellite observation.
To download OMI data, register for an Earthdata Login. Use the table below to access specific LANCE data products.
OMI / Aura
|OMCLDRR||L2 Effective Cloud Pressure and Fraction (Raman Scattering) Swath 13x24 km||0.01||N/A|
|OMTO3e||L3 TOMS-Like Ozone and Radiative Cloud Fraction Daily Global 0.25x0.25 deg||0.003||Worldview Browse (TOMS-Like Ozone)|
|OMTO3||L2 Ozone (O3) Total Column Swath 13x24 km||0.71||N/A|
|OMAERUV||L2 Near UV Aerosol Optical Depth and Single Scattering Albedo Swath 13x24 km||0.07||N/A|
|OMSO2NRTb||L2 Sulfur Dioxide (SO2) Total Column Swath 13x24 km||0.58||N/A|
Paths to files and directories via https follow similar patterns to ftp, for example the following URL ftp://omisips1.omisips.eosdis.nasa.gov/outgoing/OMCLDRR/ corresponds to https://omisips1.omisips.eosdis.nasa.gov/outgoing/OMCLDRR
You can use curl or wget in scripts to pull files; for example to get all the files in a directory the following wget command will grab the files and save to the current working directory:
wget -rnd --header='Authorization: Bearer MY_APP_KEY' https://omisips1.omisips.eosdis.nasa.gov/outgoing/OMTO3/
wget -O --header='Authorization: Bearer MY_APP_KEY' https://omisips1.omisips.eosdis.nasa.gov/outgoing/OMTO3/
OMI and OMPS downloads are being switched from ftp to http(s). NASA's Earth Science Data and Information System (ESDIS), our parent organization, requires that we track who downloads files and we do this via Earthdata Login and/or appkeys.
Earthdata Login is appropriate when using a browser as the redirection for http will work correctly. However when using the command line tools this becomes complex. To simplify this we have implemented App Keys; you generate a key and pass it to your script in a header.
Requesting an App Key
App keys are string tokens that identify who you are. App keys get passed in the authorization header of each HTTP GET request, and they last at least 3 months; which means they can be used in scripts. Any user that does not already have an app key for OMI/OMPS SIPS can get one by performing the following steps:
- Go to the Level-1 and Atmosphere Archive and Distribution System Distributed Active Archive Center (LAADS DAAC) URL: https://ladsweb.modaps.eosdis.nasa.gov/tools-and-services/
- Login by going to Profile -> Earthdata Login
- Note the first time you login via Earthdata Login, it will prompt you to accept authorization of Sentinel3 and MERIS, you must accept to continue.
- Select Profile / App Keys from the top menu
- Create your new AppKey by entering a description and clicking the "Create New App Key" button
- Highlight and copy the app key from the list and save in a file for use later.
Retrieving an App Key
Any forgotten or lost App Keys can be retrieved using the following steps:
- Login to the LAADS DAAC web site using the Profile -> Earthdata Login menu
- Select Profile / App Keys from the top menu
- Highlight and copy any existing App Keys from the list
Users are permitted to have more than one App Key at a time.
To use the App Key with wget (replace MY_APP_KEY with key copied from website):
wget -nd -r --header='Authorization: Bearer MY_APP_KEY' https://omisips1.omisips.eosdis.nasa.gov/outgoing/PATH_TO_MY_FILE
Same example with curl:
curl -H 'Authorization: Bearer MY_APP_KEY' https://omisips1.omisips.eosdis.nasa.gov/outgoing/PATH_TO_MY_FILE" > result
The example above passes your app key via the Authorization HTTP header while utilizing the Bearer schema. When finished, the resulting download will be written to a file called “result“ in whatever directory (folder) you run the command from.
The app key located in the header is how the SIPS identifies users. If the app key is invalid, or missing the command will not work.
To get a listing (to standard out) of the OMTO3 directory via wget use:
wget -nd --header='Authorization: Bearer MY_APP_KEY' https://omisips1.omisips.eosdis.nasa.gov/outgoing/OMTO3 -O -
To download a single file:
For example OMI-Aura_L2-OMTO3_2018m0529t0918-o73776_v883-2018m0529t120750.he5 go to the current directory:
wget -nd --header='Authorization: Bearer MY_APP_KEY' https://omisips1.omisips.eosdis.nasa.gov/outgoing/OMTO3/OMI-Aura_L2-OMTO3_2018m0529t0918-o73776_v883-2018m0529t120750.he5
To download all files in the OMTO3 directory to a given directory
FOO in this case and filters out any file ending in '.html' :
wget -r -nd --header='Authorization: Bearer MY_APP_KEY' -R ".html" https://omisips1.omisips.eosdis.nasa.gov/outgoing/OMTO3 -P FOO
Example scripts and more information can be found at: https://ladsweb.modaps.eosdis.nasa.gov/tools-and-services/data-download-scripts/
If using the the example scripts found on ladsweb,the URL must be changed to the omisips URL: https://omisips1.omisips.eosdis.nasa.gov/outgoing/
Page Last Updated: May 5, 2021 at 1:08 PM EDT