Some tips on searching for data using Earthdata Search.
In General:
Earthdata Search's free text search field attempts to understand free text queries. e.g. "land surface temperature over Uganda for the last 10 years" -- but its algorithm isn't perfect, and sometimes may not return useful results.
For best results,
- If you know the specific collection name, shortname, id or project you are looking for, start your search using the free text field.
- otherwise, skip the free text field, and start your search using the search "facets" (aka checkboxes) on the left to specify keywords, projects, etc.
After that, enter spacial and temporal criteria using the spacial and temporal criteria buttons located to the right of the free text field.
So for example, to search for "land surface temperature over Uganda for the last 10 years"
- Check the following checkboxes on the left:
Keywords | Land Surface | Land Temperature
Keywords | Surface Radiative Properties | Land Surface Temperature
Keywords | Surface Thermal Properties | Land Surface Temperature - Enter temporal criteria: click the clock button next to the free text field, and enter Start: 2008-01-01 00:00:00 and Stop: Today.
- Enter spacial criteria: click the compass button next to the free text field, and draw a bounding rectangle around Uganda.
Filtering granules
In granule view, you can filter the granules selected using any combination of the following:
- temporal criteria (clock button on the left) - enter / modify the date criteria
- spacial criteria (compass button on the left) - enter / modify the location criteria
- the date slider at the bottom
- the "Granule Search" field – enter one or more granule names or patterns
- the "Filter Granules" button (the funnel button on the right) - specify Day / Night, Cloud Cover and other collection-specific attributes
Searching by filename
To search for a specific granule file, you will need to know the name or id of the collection name to which it belongs.
When you have that, search for the collection, and then filter the collection's granules using the filename.
For example, to search for file N42W072.zip in in collection ASTGTM:
- Search for collection ASTGTM
- Click on the collection, and in granule view in the Granule Search field type *N42W072*
Downloading individual granules
In granule view, you can quickly download granules one at a time using one of the following buttons next to each granule:
- "Download single granule data" - direct download of unmodified granule data, without creating an order
- "Configure and download single granule data" - create an order for the granule. This allows full access to order options that might be offered by the data provider, e.g. subsetting, etc.
Recurring date example: How to search for all Novembers from 2000 to 2018:
- In the upper left corner of the screen, click the temporal icon (the clock).
- In the dialog, check "Recurring"
- In the dialog, click in "Start," then click "Nov," then click "1"
- In the dialog, click in "End," then click "Nov," then click "30"
- In the dialog, adjust "Year Range" to be 2000 - 2018
- In the dialog, click "Apply Filter"
Subsetting services: Data reformatting, reprojection, subsetting
"Subsetting services" refers to data customization options offered by data providers for select products. These may include data reformatting (e.g. to NetCDF, GeoTIFF, KLM and other file formats), data reprojection, data subsetting, and other options. Collections for which subsetting services are available are indicated with the label "SUBSETTING" following the collection name.
To see only products that support subsetting, check the "Features | Subsetting Services" checkbox on the left in collection view.
To specify subsetting services, when placing an order choose the "Customize Order" option.
Please note that subsetting services are not offered for all products, and not all subsetting-capable products support every option.
Entering grid coordinates: coordinate system options
CALIPSO
Dimensions - Orbit/Path
Enter orbit and path coordinates separated by spaces, e.g. "2,3 5,7 8,8"
Note - Orbit and Path values are not continuous and cannot be used in a range.
More info:
https://www-calipso.larc.nasa.gov/resources/calipso_users_guide/faq.php
MISR
Dimensions - Path/Block
Enter path and block coordinates separated by spaces, e.g. "2,3 5,7 8,8"
Note - Path values are not continuous and cannot be used in a range.
More info:
https://eosweb.larc.nasa.gov/
https://eosweb.larc.nasa.gov/sites/default/files/project/misr/guide/MISR_Science_Data_Product_Guide.pdf
MODIS EASE
Dimensions - Horizontal/Vertical
Enter h and v coordinates separated by spaces, e.g. "2,3 5,7 8,8"
More info:
"For MODIS Sea Ice EASE-Grid products. Tiles are 951 pixels x 951 pixels and 10 degrees by 10 degrees, with half of the tiles (313) located in the north polar grid and half in the south polar grid. In addition:
- The north polar grid tile coordinate system starts at (0,0) (horizontal tile number, vertical tile number) in the upper left corner and proceeds right (horizontal) and downward (vertical). The tile in the bottom left corner is (18,18).
- The south polar grid tile coordinate system starts at (0,20) and the tile in the bottom left corner is (18,38).
- The polar grids are based on the Lambert Azimuthal Equal Area map projection centered on each pole. The grids are compatible with the NSIDC EASE-Grid."
https://nsidc.org/data/modis/ease-grid-tile-locations-sea-ice
http://nsidc.org/data/ease
MODIS Sinusoidal
Dimensions - Horizontal/Vertical
Enter h and v coordinates separated by spaces, e.g. "2,3 5,7 8,8"
More info:
"MODIS Land products use the Sinusoidal grid tiling system. Tiles are 10 degrees by 10 degrees at the equator. The tile coordinate system starts at (0,0) (horizontal tile number, vertical tile number) in the upper left corner and proceeds right (horizontal) and downward (vertical). The tile in the bottom right corner is (35,17)."
http://spatialreference.org/ref/sr-org/modis-sinusoidal/
https://modis-land.gsfc.nasa.gov/MODLAND_grid.html
https://lpdaac.usgs.gov/dataset_discovery/modis
WELD ALASKA Tile
Dimensions - Horizontal/Vertical
Enter h and v coordinates separated by spaces, e.g. "2,3 5,7 8,8"
More info:
A U.S. Landsat ARD 30m tile system based on the Web-Enabled Landsat Data (WELD) project, with coordinates anchored in ALASKA.
| Upper Left Tile (ul corner) | Lower Right Tile (lr corner) | ||||||||
| (h) | (v) | ulX (m) | ulY (m) | (h) | (v) | lrX (m) | lrY (m) | ||
| Alaska | 0 | 0 | -851715 | 2474325 | 16 | 13 | 1698285 | 374325 | |
https://landsat.usgs.gov/what-us-ard-tile-grid
https://landsat.usgs.gov/ard#Tile%20Grid
WELD CONUS Tile
Dimensions - Horizontal/Vertical
Enter h and v coordinates separated by spaces, e.g. "2,3 5,7 8,8"
More info:
A U.S. Landsat ARD 30m tile system based on the Web-Enabled Landsat Data (WELD) project, with coordinates anchored in CONUS (the continental U.S.)
| Upper Left Tile (ul corner) | Lower Right Tile (lr corner) | ||||||||
| (h) | (v) | ulX (m) | ulY (m) | (h) | (v) | lrX (m) | lrY (m) | ||
| CONUS | 0 | 0 | -2565585 | 3314805 | 32 | 21 | 2384415 | 14805 | |
https://landsat.usgs.gov/what-us-ard-tile-grid
https://landsat.usgs.gov/ard#Tile%20Grid
WRS-1 (Landsat 1-3)
Dimensions - Path/Row
Enter path and row coordinates separated by spaces, e.g. "2,3 5,7 8,8"
More info:
"The Worldwide Reference System (WRS) is a global notation used in cataloging Landsat data. Landsat 8 and Landsat 7 follow the WRS-2, as did Landsat 5 and Landsat 4. Landsat 1, Landsat 2, and Landsat 3 followed WRS-1.""
https://landsat.usgs.gov/what-worldwide-reference-system-wrs
WRS-2 (Landsat 4+)
Dimensions - Path/Row
Enter path and row coordinates separated by spaces, e.g. "2,3 5,7 8,8"
More info:
"The Worldwide Reference System (WRS) is a global notation used in cataloging Landsat data. Landsat 8 and Landsat 7 follow the WRS-2, as did Landsat 5 and Landsat 4. Landsat 1, Landsat 2, and Landsat 3 followed WRS-1.""
https://landsat.usgs.gov/what-worldwide-reference-system-wrs
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