GEOG 121 Project 4: Finding Landsat Data Presented by: Dan LaSota Greg Stricker Weiqiang Lin

About Landsat: Purpose  The Landsat Program is established to acquire remote sensing imagery of the earth for monitoring and managing the Earth's resources.  Applications include: agriculture, geology, forestry, regional planning, education, national security and global climate change research.  Landsat 7 is the most recent NASA satellite among 6 others that have produced a continuous multispectral record of the Earth's land surface for 32 years now.  Special Emphasis on: Currency, accuracy, affordability and public accessibility of Landsat Data.  It is used across disciplines to achieve improved understanding of the Earth's land surfaces and the impact of humans on the environment.

About Landsat: Brief History  NASA initiated an Earth Resources Survey (ERS) Program 1965 to develop methods for remote sensing of earth resources from space.  First Earth Resources Technology Satellite (Landsat 1) launched in 1972 with two Earth-viewing sensing systems –a return beam vidicon (RBV) – discontinued after Landsat 3 and –an 80 meter multispectral scanner (MSS).  Original MSS measures radiation within four narrow bands that span visible green wavelengths, visible red wavelengths, and slightly longer, near-IR wavelengths.  Landsat 4 launched in 1984 with the MSS and the Thematic Mapper (TM) featuring higher spatial resolution (30 meters) and improved spectral sensitivity (7 bands, including visible blue, two mid-infrared, & thermal infrared wavelengths).  The Landsat 7 Enhanced Thematic Mapper Plus (ETM + ) Sensor was launched in Apr 1999, with improved resolution and precision, necessitated by the high costs of imaging, Land Remote Sensing Policy Act (1992) and the loss of Landsat 6.  Landsat is a tri-agency joint program of NASA, NOAA and the USGS.

About Landsat: Satellite Characteristics Source:

About Landsat: How it works? Space Segment  The ETM+ sensor onboard the spacecraft obtains data along the ground track at a fixed swath (185 km in width).  The orbit of Landsat 7 is repetitive, circular and near polar at a nominal altitude of 705 km (438 miles) at the Equator.  The spacecraft completes just over 14 orbits per day, covering the entire Earth between 81 degrees N & S latitude every 16 days.  A multispectral data set having high (30 meter) & medium to coarse (250 to 1000 meter) spatial resolution is acquired on a global basis repetitively. Source:

About Landsat: How it works? Ground Segment  Segment consists of both Landsat 7 unique components as well as institutional services. Some examples: –Landsat 7 Unique Components  Landsat Ground Station LGS, located at EDC, in Sioux Falls, SD is a receive site for the wideband X-Band downlinks of payload data from the space vehicle. X-Band downlinks X-Band downlinks  In addition to LGS, the Alaska Ground Station & the Svalbard Norway Ground Station receive payload data downlinks.  International Ground Stations are satellite data receiving stations located worldwide. They receive, process, & distribute services. –Institutional Services  Landsat Ground Network provides communication support.  Space Network – relay services  NASA Integrated Support Network – supports Institutional Services

About Landsat: Products  Level 0R Product: an essentially raw data form that is marginally useful prior to radiometric and geometric correction.  Level 1R product is a radiometrically corrected 0R product. 1R product & 0R at input level have identical geometry.  The 1G product is available to users and is a radiometrically and systematically corrected 0R image. –Can be processed by LPGS or NLAPS –Geometrically rectified for sensor/satellite/terrestrial distortions –Scene rotated, aligned, & georeferenced to a user-defined map projection. –Earthexplorer always utilize the low gain LMAX value when scaling the radiance of a scene so that all pixels saturate at the same radiance.  Others: 1P (precision corrected), 1T (terrain corrected), SLC-off Products

About Landsat: Distribution  Landsat 7 data distribution system will provide access to Landsat 7 Level 0R data products within 24 hours of collection, and  Level 1 processed products within 48 hours of request.  Media: –Exabyte tape –CD-ROM or –Electronic transfer via FTP  Imagery of foreign land masses will be recorded to EDC at Sioux Falls, yet the temporal depth will be a fraction of what's available at the international ground stations.

What is SLC-off?  An instrument malfunction occurred onboard Landsat 7 on May 31, The problem was caused by failure of the Scan Line Corrector (SLC), which compensates for the forward motion of the satellite.  The center of a SLC-off data product is very similar in quality to previous Landsat 7 data. However, the scene's edges will contain alternating scan lines of missing data or duplicated data.  As of 5/10/2004, product is in 1G form and has the gap areas filled with Landsat 7 data acquired at a similar time of year prior to the failure.  EDC has reduced the price of Landsat 7 ETM+ SLC-off scenes from $600 to $250.

What is SLC-off?

Using Landsat Data… A Digression from SLC-off

How to do Project 4 Generating Landsat Image  To find coordinates:  To generate Landsat Image:  Click on “Enter as: Guest”  Click on “Enter Coordinates” to do so in Decimals/DDMMSS  Under Data Set Selection, check the box for –“ETM+ SLC-off (Landsat 7, Jul 2003 – Present)  Click “Continue”, then “Search” on the following page  When the search is completed, click on the Data Set – “ETM+ SLC-off (Landsat 7, July present)” ETM+ SLC-off (Landsat 7, July present)ETM+ SLC-off (Landsat 7, July present)

 Click on the “Show” button, under the column “Preview Image”, that corresponds to the smallest amount of cloud cover and the most recent image.  Right click to Save Picture As (e.g. jpg) for Project 4.  Click on the “Show” button under “Show All Fields” for your image to show metadata.  Hyperlink the metadata to Project 4 - OR –Click on File and choose “Properties” –Copy the URL for the metadata  Create new page for metadata using Microsoft Frontpage –Upload it to Pass Explorer –Provide a link in Project 4 to this Metadata Page. How to do Project 4 Creating the Report

How to do Project 4 Answering the Questions  Note Scene Acquisition Date for the image you have selected.  The World Reference System (WRS) indexes orbits (paths) and scene centers (rows) into a global grid system, comprising 233 paths by 248 rows.  The standard WRS scene as defined for Landsats 4 and 5 was preserved as a product for Landsat 7.  A path distance of 90 kilometers before and after a WRS center point defines the standard scene length of 180 km (includes 20 scans of overlap) The standard WRS scene overlaps neighboring scenes along a path by 5% at the equator and has a width or cross track distance of 185 kilometers.  Definitions –The term row refers to the latitudinal center line across a frame of imagery along any given path. –The intersection of rows and paths produces the nominal scene center for that landsat image –The path/row numbers do not coincide with latitudes 90° north and south.

How to do Project 4 Answering the Questions

 Location and Extent of the Scene –Coordinates of the NW, NE, SW and SE corners can be found in the metadata  Cost of actual Landsat scene that corresponds to the free browse image: –USGS Landsat ETM+ : $ for first scene –USGS Landsat ETM+ SLC-Off : $ for first scene –

Sources  NASA Landsat Program (2004)  Landsat 7 Science Data Users Handbook (2004)  U.S. Census Bureau (2000)  USGS Earthexplorer (2004)  USGS Landsat Project (2004)  Esri Online Campus (2004)