Landsat Missions

Landsat 8 (L8) Data Users Handbook - Section 1

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Section 1 – Introduction

Section 2 – Observatory Overview

Section 3 – Instrument Calibration

Section 4 – Level-1 Products

Section 5 – Conversion of DNs to Physical Units

Section 6 – Data Search and Access

Appendix A – Known Issues

Appendix B – Metadata File (MTL.txt)

References

Download Landsat 8 (L8) Data User Handbook (.pdf 4.39 MB)


Section 1 - Introduction

1.1 Foreword

1.1 Foreword
The Landsat Program has provided over 45 years of calibrated medium spatial resolution data of the Earth's surface to a broad and varied user community, including agribusiness, global change researchers, academia, state and local governments, commercial users, national security agencies, the international community, decision-makers, and the general public. Landsat images provide information meeting the broad and diverse needs of business, science, education, government, and national security.

The mission of the Landsat Program is to provide repetitive acquisition of moderate-resolution multispectral data of the Earth's surface on a global basis. Landsat represents the only source of global, calibrated, moderate spatial resolution measurements of the Earth's surface that are preserved in a national archive and freely available to the public. The data from the Landsat spacecraft constitute the longest record of the Earth's continental surfaces as seen from space. It is a record unmatched in quality, detail, coverage, and value.

 

The Landsat 8 observatory offers these features:

  • Data Continuity: Landsat 8 is the latest in a continuous series of land remote sensing satellites that began in 1972.
  • Global Survey Mission: Landsat 8 data systematically builds and periodically refreshes a global archive of sun-lit, substantially cloud-free images of the Earth's landmass.
  • Free Standard Data Products: Landsat 8 data products are available through the USGS EROS Center at no charge.
  • Radiometric and Geometric Calibration: Data from the two sensors, the Operational Land Imager (OLI) and the Thermal Infrared Sensor (TIRS), are calibrated to better than 5% uncertainty in terms of top-of-atmosphere reflectance or absolute spectral radiance, and having an absolute geodetic accuracy better than 65 meters circular error at 90% confidence (CE 90).
  • Responsive Delivery: Automated request processing systems provide products electronically within 48 hours of order (normally much faster).
     

The continuation of the Landsat Program is an integral component of the U.S. Global Change Research Program and will be used to address a number of science priorities, such as land cover change and land use dynamics. Landsat 8 is part of a global research program known as NASA’s Science Mission Directorate, a long-term program that is studying changes in Earth's global environment. In the Landsat Program tradition, Landsat 8 continues to provide critical information to those who characterize, monitor, manage, explore, and observe the land surfaces of Earth over time.

The U.S. Geological Survey has a long history as a national leader in land cover and land use mapping and monitoring.  Landsat data, including Landsat 8 and archive holdings, are essential for USGS efforts to document the rates and causes of land cover and land use change, and to address the linkages between land cover and use dynamics on water quality and quantity, biodiversity, energy development, and many other environmental topics.  In addition, the USGS is working toward the provision of long-term environmental records that describe ecosystem disturbances and conditions.  

1.2 Background

The Land Remote Sensing Policy Act of 1992 (U.S. Code Title 15, Chapter 82) directed the federal agencies involved in the Landsat program to study options for a successor mission to Landsat 7, ultimately launched in 1999 with a five-year design life, that maintained data continuity with the Landsat system. The Act further expressed a preference for the development of this successor system by the private sector as long as such a development met the goals of data continuity.

The Landsat 8 project suffered several setbacks in its attempt to meet these data continuity goals.  Beginning in 2002, three distinct acquisition and implementation strategies were pursued:  (1) purchase of observatory imagery from a commercially owned and operated satellite system partner (commonly referred to as a government “data buy”), (2) flying a Landsat instrument on NOAA’s NPOESS series of satellites, and (3) finally selection of a “free-flying” Landsat satellite.  Considerable delays to Landsat 8 implementation were incurred as a result.  The matter wasn’t resolved until 2007 when it was determined that NASA would procure the next mission space segment and the USGS would develop the ground system and operate the mission after launch. 

The basic Landsat 8 requirements remained consistent through this extended strategic formulation phase of mission development. The 1992 Land Remote Sensing Policy Act (U.S. Code Title 15, Chapter 82) established data continuity as a fundamental goal and defined continuity as providing data “sufficiently consistent (in terms of acquisition geometry, coverage characteristics, and spectral characteristics) with previous Landsat data to allow comparisons for global and regional change detection and characterization.” This direction has provided the guiding principal for specifying Landsat 8 requirements from the beginning with the most recently launched Landsat satellite, Landsat 7, serving as a technical minimum standard for system performance and data quality.

1.2.1 Previous Missions

Landsat satellites have been providing multispectral images of the Earth continuously since the early 1970's. A unique 45 year data record of the Earth's land surface now exists. This unique retrospective portrait of the Earth's surface has been used across disciplines to achieve improved understanding of the Earth's land surfaces and the impact of humans on the environment. Landsat data have been utilized in a variety of government, public, private, and national security applications. Examples include land and water management, global change research, oil and mineral exploration, agricultural yield forecasting, pollution monitoring, land surface change detection, and cartographic mapping.

Landsat 8 is the latest satellite in this series. The first was launched in 1972 with two Earth-viewing imagers - a return beam vidicon (RBV) and an 80-meter 4-band multispectral scanner (MSS). Landsat 2 and 3, launched in 1975 and 1978 respectively, were configured similarly. In 1984, Landsat 4 was launched with the MSS and a new instrument called the Thematic Mapper (TM). Instrument upgrades included improved ground resolution (30 meters) and 3 new channels or bands. In addition to using an updated instrument, Landsat 4 made use of the multi-mission modular spacecraft (MMS), which replaced the Nimbus based spacecraft design employed for Landsats 1-3. Landsat 5, a duplicate of Landsat 4, was launched in 1984 and returned scientifically viable data for 28 years - 23 years beyond its 5-year design life. Landsat 6, equipped with an additional 15-meter panchromatic band, was lost immediately after launch in 1993. 

Finally, Landsat 7 was launched in 1999 and performed nominally until its scan line corrector (SLC) failed in May 2003.  Since that time, Landsat 7 continues to acquire to this day useful image data in the “SLC off” mode.  All Landsat 7 SLC-off data are of the same high radiometric and geometric quality as data collected prior to the SLC failure.

Figure 1-1 lists the continuity of multispectral data coverage provided by Landsat missions beginning with Landsat 1 in 1972.

Figure 1-1 . Continuity  of Multispectral Data Coverage Provided by Landsat Missions
Figure 1-1 . Continuity of Multispectral Data Coverage Provided by Landsat Missions

1.2.2 Operations & Management

The Landsat 8 management structure is composed of an ongoing partnership between NASA and USGS for sustainable land imaging.  NASA contracted Ball Aerospace and Technology Corporation to develop the Operational Land Imager and with Orbital Sciences Corporation to build the spacecraft.  The Thermal Infrared Sensor was built by NASA Goddard Space Flight Center.  NASA was also responsible for the satellite launch and completion of a 90-day on-orbit check out before handing operations to the USGS.  The USGS was responsible for the development of the ground system and is responsible for operation and maintenance of the observatory and the ground system for the life of the mission.  In this role, the USGS captures, processes, and distributes Landsat 8 data and is responsible for maintaining the Landsat 8 data archive. 

The Landsat Project at the USGS Earth Resources Observation and Science (EROS) Center manages the overall Landsat 8 Mission Operations. In this capacity, USGS EROS directs on-orbit flight operations, implements mission policies, directs acquisition strategy, and interacts with International Ground Stations.  USGS EROS captures Landsat 8 data and performs pre-processing, archiving, product generation, and distribution functions.  USGS EROS also provides a public interface into the archive for data search and ordering.

1.3 Landsat 8 Mission

The Landsat 8 mission objective is to provide timely, high quality visible and infrared images of all landmass and near-coastal areas on the Earth, continually refreshing an existing Landsat database. Data input into the system is sufficiently consistent with currently archived data in terms of acquisition geometry, calibration, coverage and spectral characteristics to allow for comparison of global and regional change detection and characterization.

1.3.1 Overall Mission Objectives

Landsat 8 has a design lifetime of five years and carries 10 years of fuel consumables. The overall objectives of the Landsat 8 mission are:

  • Provide data continuity with Landsats 4, 5, and 7.
  • Offer 16-day repetitive Earth coverage, an 8-day repeat with a Landsat 7 offset.
  • Build and periodically refresh a global archive of sun-lit, substantially cloud-free, land images.

 1.3.2 System Capabilities

The Landsat 8 system is robust, high performing, and of extremely high data quality.  System capabilities include:

  • Provides for a systematic collection of global, medium-resolution, multispectral data.
  • Provides for a high volume of data collection.  Unlike previous missions, Landsat 8 far surpasses the average collection of 400 scenes per day.  Landsat 8 routinely surpasses 650 scenes per day imaged and collected in the USGS archive.
  • Uses cloud cover predicts to avoid acquiring less useful data.
  • Ensures all data imaged are collected by a U.S. ground station.

 

The Landsat 8 observatory offers many improvements over its predecessor, Landsat 7. See Table 1-1 for a high level comparison of Landsat 7 and Landsat 8 observatory capabilities.  These will be discussed further in the following sections. 

Table 1-1 . Comparison of Landsat 7 and Landsat 8  Observatory Capabilities
Table 1-1 . Comparison of Landsat 7 and Landsat 8 Observatory Capabilities

1.3.3 Global Survey Mission

An important operational strategy of the Landsat 8 mission is to establish and maintain a global survey data archive. Landsat 8 follows the same "Worldwide Reference System" used for Landsats 4, 5, and 7 bringing the entire world within view of its sensors once every 16 days.

Also, similar to Landsat 7, Landsat 8 operations endeavor to systematically capture sun-lit, substantially cloud-free images of the Earth’s entire land surface. Initially developed for Landsat 7, the Long Term Acquisition Plan (LTAP) for Landsat 8 defines the acquisition pattern for the mission in order to create and update the global archive to ensure global continuity. 

1.3.4 Rapid Data Availability

Landsat 8 data are downlinked and processed into standard products within 24 hours of acquisition.  Level-0R, Level-1Gt, Level-1T, and LandsatLook products are available through the User Portal.  All users are required to register through EarthExplorer.

All products are accessible via the internet for download via HTTP; there are no product media options. 

As with all Landsat data, products are available at no cost to the user.  Available data can be viewed through a number of interfaces:

1.3.5 International Ground Stations

Landsat has worked cooperatively with international ground stations for decades.  For the first time in the history of the Landsat mission, all data downlinked to international ground stations are written to the Solid State Recorder and downlinked to USGS EROS for inclusion in the USGS Landsat archive.   There are no unique data held at international ground stations.  Updated information and a map displaying international ground stations is available.

1.4 Document Purpose

The Landsat 8 Data Users Handbook is a living document prepared by the U.S. Geological Survey Landsat Project Science Office at the Earth Resources Observation and Science (EROS) Center in Sioux Falls, SD and the NASA Landsat Project Science Office at NASA's Goddard Space Flight Center in Greenbelt, Maryland. Its purpose is to provide a basic understanding and associated reference material for the Landsat 8 observatory and its science data products.

1.5 Document Organization

This document contains the following sections:

  • Section 1 provides a Landsat program foreword and introduction
  • Section 2 provides an overview of the Landsat 8 observatory
  • Section 3 provides an overview of instrument calibration
  • Section 4 discusses Level-1 Products
  • Section 5 addresses the conversion of product DNs to physical units
  • Section 6 identifies data search and access portals
  • Appendix A addresses known issues associated with Landsat 8 data
  • Appendix B displays the metadata file.
  • The References section contains a list of applicable documents

 

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Landsat represents the world's longest continuously acquired collection of space-based moderate-resolution land remote sensing data. Four decades of imagery provides a unique resource for those who work in agriculture, geology, forestry, regional planning, education, mapping, and global change research. Landsat images are also invaluable for emergency response and disaster relief.

 

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