Accessing ABoVE airborne data using Earthdata Search

Speakers: Jessica Welch

• Author: ORNL DAAC
• Date: January 6, 2019
• Contact ORNL DAAC: uso@ornl.daac.gov

Keywords: ABoVE, Airborne

Overview

This tutorial demonstrates how to use Earthdata Search to access and download data from the ABoVE airborne campaign for a spatial region of interest. Earthdata Search is a NASA Earth Observing System Data and Information System client for discovering, searching, visualizing, and retrieving Earth science data.

Tutorial Link

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Source Data

Miller, C.E., R.O. Green, D.R. Thompson, A.K. Thorpe, M. Eastwood, I.B. Mccubbin, W. Olson-duvall, M. Bernas, C.M. Sarture, S. Nolte, L.M. Rios, M.A. Hernandez, B.D. Bue, and S.R. Lundeen. 2018. ABoVE: Hyperspectral Imagery from AVIRIS-NG for Alaskan and Canadian Arctic, 2017. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/1569

Prerequisites

Sign up for a NASA Earthdata account: https://urs.earthdata.nasa.gov/users/new

Tutorial

This tutorial demonstrates how to use Earthdata Search to access and download data from the ABoVE airborne campaign for a spatial region of interest. Earthdata Search is a NASA Earth Observing System Data and Information System client for discovering, searching, visualizing, and retrieving Earth science data.

1. Begin by opening your favorite web browser and navigating to the Earthdata Search client web site at https://search.earthdata.nasa.gov/search.
2. Log into your Earthdata account, by clicking the "Earthdata Login" button in the top-right corner of the page. If you don’t have an account, you can create one using the same button. You will need to do this in order to download data.

1. For this tutorial, we are interested in data collected during the Summer 2017 ABoVE airborne campaign using the AVIRIS-NG instrument. AVIRIS stands for the Airborne Visible InfraRed Imaging Spectrometer, and it is used for Earth remote sensing. Search for ‘aviris’ in the search box at the upper-left hand corner of the screen.
2. In the collections section on the bottom half of the page, you will see a list of data collections that include data related to AVIRIS. You can explore these collections in detail, but we want only AVIRIS data collected for the ABoVE campaign. More specifically, we want AVIRIS data collected near the Toolik Field Station in the foothills region of the Brooks Range, northern Alaska.
3. Click on the map and use the mouse to move the map so that Alaska is shown. Then zoom in on the state by double clicking. Now, select the fourth icon (a square) which is a tool to "search by spatial rectangle." If you hover your mouse pointer over the icon you can see its name.
4. In the map area, click on a point in northern Alaska and drag your cursor to draw a rectangle. That action will filter the collections to show only those that have data located within the rectangular spatial extent on the map. In the collections area, only one collection will now be shown: "ABoVE: Hyperspectral Imagery from AVIRIS-NG for Alaskan and Canadian Arctic, 2017".
5. Click on the collection title and it will display the data files (known as granules) and information about when the data were collected and an associated timeline for the collection. Notice that you can sort the granules by start and end dates of data collection by clicking the drop-down menu next to "Sort by:" in the upper, left-hand corner of the collections area. In the map area, you can view the locations for each granule. Try clicking on a rectangle to see information for its corresponding granule. Alternatively, in the collections area, you can click on granule to see its location in the map area. Using the timeline, you can zoom in or out to see granules organized by when data were collected.
6. At this point, you can download all granules included in your rectangular spatial extent by clicking on the green button titled "Download All" located in the top right corner of the collections area. But, next we are going to learn how to refine our search to select only those data collected over our particular study site.

1. We can use the latitude and longitude of a location to more precisely search for data. For this tutorial, we want granules that include the area of the Toolik Lake Field Station. Go to the search box and you will see three icons in the white background area. Select the second icon (a square like the corner of a box). Select the third option in the drop-down menu: "Point." Now type in the geographic coordinates of Toolik Lake at 68.6381, -149.3.
2. In the collections area, you should now see six granules that cover the location of the Toolik Field Station. When you look closer at the start and end dates, you can see that there are two granules each for three different days—September 8th, 9th, and 13th, 2017. If you look closely at the names of the granules you will see that three granules have "rfl" at the end of the filename, which means that they contain reflectance data. We want to download only the reflectance data, so click the "X" icon for the other three, non-reflectance, granules to remove them from the collections area.

1. Now we have selected all the granules of interest, but before we begin our download, let's get some documentation and a user guide for the dataset. In the collections list area, next to the title of the dataset, there is an "i" icon and "View details” link. Click that link to see additional information about the dataset. Now click the link "View All Related URLs" to see several different options to view documentation, a browse image, or the dataset landing page at the ORNL DAAC.
2. Close the Related URLs window and navigate back to the granules from the collections area. Now we will download the granules by clicking the green download link to the right of the screen in the collections area. You will be re-directed to a Data Access page to review your data request. From here, there are two methods to access the data: Direct Download or Stage for Delivery (which means you will receive an email with the download links). Since we have only three granules, we will download the data directly. Click the "Submit" button in the bottom, right-hand corner to get the download links or access a script that you can run from the command line.