Landsat Images: an Overview of Worldwide Data Access

Landsat is a family of satellites developed by NASA which provide since 1972 (launch of Landsat 1) remote sensing images with inestimable value for worldwide environmental monitoring (see this page).
With the launch of Landsat 8 in 2013, NASA assured the continuity of data acquisition for the next few years. Landsat 8 has the new sensor OLI (Operational Land Imager) which improves the quality of images and therefore allows for better land cover monitoring. A comparison of band designation for the Landsat satellites is described here.
At least 400 scenes are collected daily, placed into the USGS archive and made available at no charge; in the past 40 years of Landsat acquisition over 3 million images were collected in a huge archive of data, and millions of images were downloaded.

Over 20 Million Landsat Scenes Downloaded (from USGS http://landsat.usgs.gov/images/gallery/360_L.jpg)

Landsat images are delivered in several ways, and through several web sites. In fact, images are also collected by the USGS International Cooperator ground stations, which are the primary source of distributing data collected at their location (see http://landsat.usgs.gov/about_ground_stations.php)

This post is an overview about where Landsat images can be downloaded for free.

Data for the entire world:

  • EarthExplorer
    Developed by USGS, this is probably one of the best applications for accessing Landsat images (and images of other NASA satellites  such as MODIS, or specific products for the USA). User can select the search area, the sensor type (from Landsat 1 to Landsat 8), and browse the result inside a Google map viewer.
    A free registration is required for downloading images.


  • An online viewer by USGS focused on Landsat data (from Landsat 1 to Landsat 8). A simple interface allows for the interactive browsing of Landsat scenes (of a zoomed area), filtered by date and cloud cover, shown inside a map viewer.
    A free registration is required (the same as EarthExplorer).

  • A project funded by NASA that produced mosaics from Landsat terrain corrected (Level 1T) data. Data are available through an interactive interface which allows for the selection of the area and period of acquisition (month of the year from 2009 to 2011). Data products are already processed. 
    For each product period the single best Landsat observation at each pixel location is selected using a compositing algorithm (see here). Each WELD product pixel has 23 bands storing the information described here, which include Top of atmosphere (TOA) reflectance, brightness temperature, and NDVI TOA.
    Registration is required. Order confirmation and data access is provided through emails.

Data for Europe:

  • This ESA portal is specific for Landsat 8 images, and allows for browsing and downloading data mainly acquired over Europe (and North Africa). The simple interface provides an easy way of searching images and downloading preview images as TIF or KMZ. Images are available within three hours of acquisition.
    Other Landsat images are freely available through the application EOLi. A free registration is required.
    The following video illustrates a Landsat 8 image and the ESA Landsat 8 Web Portal (by ESA Earth from Space which broadcasts new videos every Friday).



Data for Africa:


  • The Gabonese Agency for Space Studies and Observations developed an online catalog which allows for searching and browsing images from Landsat (and other satellite such as SPOT). The search area is limited to the West Africa. Registration is required.


Data for Asia:

  • By the Chinese Center for Earth Observation and Digital Earth, this site provides access to Landsat images through a WebGIS interface.

Data for South America:

  • Provided by the Brazilian Instituto Nacional de Pesquisas Espaciais, this web application allows for searching and downloading Landsat images (from 1 to 7) for almost the entire South America.
    Registration is required for downloading data.

  • The Argentinian Comisión Nacional de Investigaciones Espaciales provides access to Landsat images through an online catalog. Email contact is required for downloading images.

The above sites are only a few ways of accessing Landsat data. Several other websites offer access to Landast images, such as the Global Land Cover Facility (by University of Maryland) which provides Landsat images (and reflectance data) for the time epochs 1975, 1990, 2000, 2005, 2010, also via FTP server (ftp://ftp.glcf.umd.edu/glcf/Landsat/). In addition, the Australian Government provides near real time satellite imagery products (also Landsat 7 and Landsat 8 acquired in the last few days) via FTP (ftp://ftp.ga.gov.au/outgoing-emergency-imagery/). Other global orthorectified Landsat images are available from http://www.landsat.org/ortho/.
Finally, it is worth mentioning this nice application by USGS (requires Java) that displays the Landsat 7 data received in near-real time, which is good for educational purposes.

Given the huge availability of Landsat data, land cover monitoring is affordable and reliable. In a previous post I described several applications related to the supervised classification of Landsat images.
The Semi-Automatic Classification Plugin has a specific tool for converting Landsat bands to TOA reflectance, with the option of performing a DOS1 (Dark Object Subtraction) atmospheric correction. Recently, USGS announced that prototype Landsat 8 Surface Reflectance product options will be available in the next few months, which could enhance and simplify the use of data.

Please, remember that a Facebook group and a Google+ Community are available for sharing information and asking for help about the Semi-Automatic Classification Plugin.
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