NASA's Earth science data archive holds more than 100 petabytes of free and open-access data and is growing rapidly. This is welcome news to the community of Earth science data users around the globe who rely on NASA data to conduct their scientific research and monitor conditions on land, in the ocean, and in the atmosphere. At the same time, this vast and ever-growing catalog can make it difficult for data users, especially those new to working with remotely sensed data, to find the data that meet their needs.
To address this challenge, NASA's Earth Science Data and Information System (ESDIS) Project created Earthdata Search, a web application that enables users to discover and access more than 50,000 Earth observation data collections from NASA's Earth Observing System Data and Information System (EOSDIS), as well as from U.S. and international agencies across the Earth science disciplines. Using NASA's Common Metadata Repository (CMR) as a foundation, Earthdata Search eases the technical burden on users by providing them with a high-quality tool that makes it easy to search for datasets by date and geographic area, preview browse images for select datasets, and download data.
"Earthdata Search is your one-stop shop for finding and accessing NASA Earth science data." said Alicia Aleman, the Earthdata Search product owner. "Users can search more than one billion individual data files all in one place; it makes it possible to get the data you're interested in—and only those data—quickly and easily."
Earthdata Search Requires an Earthdata Login to Download Data
While users don't need any special knowledge or training to use Earthdata Search, they do need an Earthdata Login account to download NASA Earth science data. Along with facilitating data downloads, Earthdata Login provides an improved user experience by enabling single sign-on functionality, the ability to receive news updates and notifications about new data and services, and the creation of customizable interfaces and saved preferences. Further, logging into Earthdata Search allows users to download data collections or granules directly to a local machine or add them to a project folder.
Getting Started with Earthdata Search: Searching for and Filtering Data
Although it would be impossible to cover all the ways a user might use Earthdata Search to find and download data within the framework of this article, most searches include three elements: a keyword search, a date range, and a geographic area of interest. This article provides an overview of this approach to using Earthdata Search.
There are three main components of Earthdata Search: The search panel on the left, which allows users to search for and filter data; the results panel in the center, which displays the data collections resulting from the user's search criteria; and the map on the right, which displays a map of Earth's surface. Once a user is logged in, he or she can begin their search by typing a data identifier or keyword (i.e., science parameter, data product, sensor, satellite, etc.) into the search box at the top of the left panel.
After entering a search term and pressing enter, the search results (i.e., the data collections associated with that keyword or search term) will appear in Earthdata Search's center panel. By default, search results are ordered by usage (the most popular collections are listed first). Users can re-order these results by relevance to search criteria or start or end date by clicking on the "Sort" button found in the top-right of the center panel. Users also can use the "View" button (next to "Sort"), which allows them to view their search results as a list or a table.
Should the results of the keyword search be too numerous, users can refine them further via the array of filters available in the panel on the left. These include:
- Date Range: Clicking the calendar icon opens a pop-up window in which users can choose the date range of the data they seek
- Geographic Search: Clicking the geographic search tool (to the right of the calendar) allows users to draw a polygon, rectangle, point, or circle on the map in the right panel, or upload a shapefile
- Dataset Feature: Allows users to filter their search results by whether the data are available in the Earthdata Cloud, are customizable, or offer map imagery
- Dataset Feature Filters: Users have the option to refine their search results by science parameter, platform, instrument or sensor, data processing level, organization, data format, resolution, latency, and tiling system
As Aleman points out, when users first open Earthdata Search they will see thousands of data collections available. However, if they're interested in data about a particular topic (e.g., carbon dioxide), entering that term in the search box will bring the number of collections down. Users can filter these results further with the options in the left panel. For Aleman, the first three filtering options—Available in the Earthdata Cloud, Customizable, and Map Imagery—function as shortcuts for restricting results to only collections offering these capabilities. Users can then refine these results further with the remaining filters on the left panel.
"There are a number of options that allow users to filter their initial search results down to a manageable number that they can then evaluate to determine whether or not those data are going to be useful," Aleman said.
Evaluating Search Results
After the list of data collections in the center panel has been sorted and filtered, users can then begin evaluating their utility. To do this, users should first look at the basic information provided about each collection. This includes a brief description about the collection, the number of files (or granules) the data collection contains, its temporal range, and a set of badges indicating the advanced features the collection supports. These features include map visualization, available customizations (i.e., whether the data can be subset or reformatted), and whether the data are accessible via the Earthdata Cloud.
Further, when users hover their cursor over a particular collection, an icon with a lowercase "i" in a circle appears. Clicking on this icon opens a new page with additional information about the collection, including a description of the data collection, the collection's digital object identifier (DOI), the native format of the data and options for data reformatting, and the NASA Distributed Active Archive Center (DAAC) that archives and distributes the data. This page also features additional links that take users to the Dataset Landing Page, Related URLs, citation information, and more information about the data from NASA's CMR.
Once users have determined which collections in the search results are most relevant, they can click on a particular collection of interest to evaluate the data files (or granules) that collection contains. This will open a new page listing all of the individual files associated with that collection. (Users should note that when they arrive on this page, the filters in the left panel change to allow for additional filtering of the granules contained in the collection.) On this page, users can click on each file to see its data footprint (the footprint will be outlined in green on the map in the right panel), which enables them to evaluate how the selected data granule overlaps with their area of interest. In addition, if the collection has sample imagery associated with it, that imagery will appear on the map as well. There is also a timeline at the bottom of the page that provides users with a visual indication of how the date range of each file overlaps with their selected date range of interest.
"All of the information available on these pages is designed to help users evaluate the list of data collections and pare them down to just the ones they're interested in," said Aleman. "Hovering over or clicking on an individual granule file highlights the footprint on the map, allowing users to see how each individual file overlaps with their area of interest."
Downloading the Data
When users have decided which data files best meet their needs, they can select the files they'd like to download in several ways. If users want to download all of the files in a particular collection, they can click the "Download All" button in the bottom right corner of the center panel and the application will guide them through the download process. Conversely, if a user wants to download only one or two files from a particular collection, he or she can click the green plus (+) sign associated with each of the files. Any collection or file selected for download is automatically added to the user's project folder. Users can add multiple collections or data files (including files from different collections) to their projects for simultaneous download.
To download their selected files, users should click the "My Project" button in the top right of the application window. This will open a new page with information showing the number of files selected for download and the estimated size of the entire download file on the left, the options for downloading the data (e.g., direct download or customization options) in the center, and a timeline showing how the files overlap with the user's selected date range on the bottom. Once all options for download and any customizations have been addressed, the data can be downloaded by clicking the "Done" button at the bottom of the page and then the "Download Data" button in the bottom-left corner of the screen. This brings users to a page featuring information about the status of the download, links for accessing the data, and links to any associated browse imagery.
Assistance and Resources
The above sections provide a basic overview of how users can enlist Earthdata Search to search for, evaluate, and download NASA Earth science data. Given the expansive functionality the application offers, this article covers only the basic steps for using Earthdata Search. Fortunately, there are several in-depth presentations and other resources available to help users make the most of this tool and that discuss some of Earthdata Search's more advanced features. In addition, there is a "Feedback" button in the top-right corner of the Earthdata Search webpage that allows users to pose questions to the Earthdata Search team. In addition, the Earthdata Forum allows users to get answers to questions from subject matter experts.
Resources
- Earthdata Search general information page
- Earthdata Search FAQ
- Webinar: Discover and Access Earth Science Data Using Earthdata Search (2024)
- Webinar: Learn How to Discover, Access, and Customize Multiple Datasets (and Data Types) with Earthdata Search (2021)
- Webinar: Discover Earth Science Data with NASA Earthdata Search (2016)
- Earthdata Search APIs
