Satellite Data Services -- An Introduction

This page will introduce the reader to the type of data that is collected by NOAA satellites, how it is delivered or made available to users, or NOAA satellite (and other) data that is delivered via satellite. While NOAA is no longer responsible for Landsat satellite operations, a brief overview is provided here for completeness.

High Resolution Picture Transmission ( HRPT )

HRPT is worldwide direct readout of high resolution (1 km) spacecraft parameters and instrument data to ground stations within the footprint of the NOAA polar orbiters. The HRPT service was originally designed to provide timely day and night sea surface temperature, ice, snow and cloud cover information to diverse users, but applications have expanded due to the proliferation of moderately priced equipment and software. NOAA maintains a two-satellite "constellation" of polar orbiters; with this configuration, any particular location on Earth can receive data from a satellite approximately every 6 hours. HRPT transmissions contain data from nearly all instruments aboard the NOAA polar satellites. The data stream includes information from the High Resolution Infrared Sounder (HIRS), Stratospheric Sounding Unit (SSU), Microwave Sounding Unit (MSU), Solar Backscatter Ultraviolet Radiometer (SBUV), Space Environmental Monitor (SEM), Argos Data Collection unit, TIROS Information Processor (which contains spacecraft attitude data, time codes, housekeeping, telemetry, etc.), and the Advanced Very High Resolution Radiometer (AVHRR).

To receive the data, users can purchase the necessary equipment (computer, software, antenna) from commercial companies* for unlimited access to the HRPT signals. There is no fee or license requirement required by NOAA to receive this data. Archived data are also available from NOAA, some commercial companies and other sites either processed or in raw form. Data acquired in this manner usually incurs a fee for reproduction.

Automated Picture Transmission ( APT )

APT is 4 km resolution infrared and visible imagery derived from the AVHRR instrument and transmitted within the footprint of the NOAA polar orbiters. Normally one channel of visible data and one channel of infrared data are transmitted during daytime, and two infrared channels are transmitted during the nighttime hours. Since APT is captured on low cost ground stations, it is also very popular in schools and for individuals. Users purchase the necessary equipment (computer, software, antenna) from commercial companies* for unlimited access to APT signals. There is no fee or license requirement required by NOAA to receive this data.

GOES Variable Format ( GVAR )

GVAR is the transmission of full resolution GOES data to ground stations within the footprint of NOAA's operational geostationary satellites GOES-12 (75W) and GOES-10 (135W), respectively. Dissemination schedules are maintained by NESDIS. With a geostationary orbit, any location within the satellite "footprint" is able to receive nearly continuous data coverage. To receive the data, users can purchase the necessary equipment (computer, software, antenna) from commercial companies* for unlimited access to GOES signals. There is no fee or license requirement required by NOAA to receive this data. Archived data are available from NOAA, some commercial companies and other sites either processed or in raw form. Data acquired in this manner usually incurs a fee for reproduction.

Weather Facsimile ( WEFAX )

WEFAX is the retransmission of low-resolution infrared and visible satellite imagery and graphical meteorological data to low cost satellite ground receiving stations located within the footprint of geostationary satellites. NESDIS manages the U.S. program, which provides access to NOAA GOES and POES satellite imagery as well as some European Meteosat and Japanese GMS satellite imagery, NWS charts and polar satellite orbital elements (TBUS). Transmission schedules and other information are maintained by NESDIS. To receive WEFAX, users purchase the necessary equipment (computer, software, antenna) from commercial companies* for unlimited access to WEFAX signals. There is no fee or license requirement required by NOAA to receive this data. Because of its low cost and high value, many schools and individuals capture and utilize WEFAX data.

WEFAX will be replaced with a new digital transmission (Low Rate Information Transmission/LRIT) in early 2005.  This will require major modification or replacement of WEFAX receivers. During 2003, test LRIT transmissions will be sent from the GOES-East satellite. During 2004, a schedule will be established with regular alternating WEFAX and LRIT transmissions from the GOES satellites. In early 2005, NOAA expects to entirely replace WEFAX with LRIT. Many of the present WEFAX receiver manufacturers will begin offering LRIT receiving systems during 2003 and 2004. Technical details of the transition can be found at the WEFAX-LRIT transition web site.

GOES Data Collection System ( DCS )

Since 1975, NESDIS has managed the U.S. DCS, a system consisting of in-situ platforms collecting environmental information, an operational processing center located at the NOAA Command and Data Acquisition station in Wallops, Virginia, program management and oversight located in Camp Springs, Maryland, and several communications links to the collected data. Environmental data are collected from platforms located primarily in remote areas (rivers, lakes, oceans, land) and within the footprint of the NOAA geostationary satellites. The GOES satellite acts as the communications link between the remote platform and processing facility. After obtaining an agreement with the National Environmental Satellite Data and Information Service (NESDIS), the data are processed at Wallops and made available to customers either via a domestic communication satellite (DOMSAT), the NOAA GOES satellite or dial-in modem to Wallops. Access via Internet is currently being tested. Most environmental observations processed through GOES, along with observations within the footprint of the European Meteosat and Japanese GMS satellites, are also available from the Global Telecommunications System (GTS) weather circuits. To receive information about the GTS, contact your local WMO office or national meteorological agency.

DCS customers include U.S. and international agencies responsible for monitoring environmental and earth resources where observations are needed frequently and quickly. Some examples include U.S. and Mexican Weather Service flood warning and forecasting, United States Geological Survey earthquake monitoring, and U.S. Forest Service forest fire operations.

A DCS user group was formed in the 1980s and meets several times a year at various locations within the U.S. to discuss system enhancements and policies. To use the GOES DCS system or receive data from international DCS systems, customers provide program requirements and other administrative information which forms the basis of a Memorandum of Agreement with NESDIS. For more information about DCS, contact Kay Metcalf, DCS Coordinator at (301)457-5681 x125, Email: kay.metcalf@noaa.gov, or the GOES DCS web site. Also available is the GOES DCS User's Guide.

Polar Data Collection ( Argos )

Argos is satellite-based global environmental data collection and location program jointly operated by the United States and France. Operational since 1978, Argos was established by joint agreement between NESDIS, NASA, and the French Space Agency, Centre National d Estudes Spatiales (CNES). Environmental data and other information are collected from fixed and moving platforms. The data are processed and made available from CNES via Service Argos, which is headquartered in France. Service Argos also has an office in the Landover, Maryland. Approximately five percent of the Argos system capacity is available for non-environmental applications.

The Argos system consists of: Platform Terminal Transmitters (PTTs) equipped with sensors and transmitters; Argos instruments carried aboard the NOAA polar orbiting satellites; ground processing systems located at NESDIS (Suitland, Maryland), CNES and Service Argos; and telemetry ground stations in the U.S., Australia and elsewhere. Major programs supported include the Tropical Ocean and Global Atmosphere project, World Ocean Circulation Experiment, and tracking of marine and terrestrial animals.

To use the Argos system, inquires and program information must be submitted to CNES via Service Argos in Toulouse, France or Landover, Maryland. Much of the data collected by Argos is disseminated via the Global Telecommunications System for input to the World Weather Watch and can be obtained without deploying any platforms. At present, agreements between NOAA, CNES and NASA ensure the Argos program continues through the NOAA-N' spacecraft.

In response to user-identified priorities, several changes were implemented with the launch of NOAA-15 and the first Argos-2 instrument (May 1998). System improvements will continue with NOAA-L,M, N and the Japanese satellite, ADEOS-II. Specifically, the new Argos system will enable:

1) more sensor data and locations by processing data from additional satellites, and through such instrument enhancements as increased on-board capacity, wider receiver bandwidth, and more flexible management of transmitter repetition periods.

2) greater sensitivity to low-power signals;

3) relaying commands to transmitters (e.g., "downlink messaging").

Plans are underway for another generation of Argos instrument (Argos-3) to possibly be carried aboard future missions. For more information about Argos, in the Americas, contact Service Argos at +1 (301)925-4411, or elsewhere CNES in France at +33 61-39-47-00, or see the Argos home page

NOAAport

NOAAport is a multichannel data dissemination system that uses a commercial communications satellite, transmitting in the C band. This system has been designed primarily for the National Weather Service, but is available to anyone with the appropriate receiver. The data stream consists of processed high resolution GOES imagery as well as National Weather Service graphic and alphanumeric products. All of the information on the NOAAport broadcast is primarily oriented for North America. More information can be found on the NOAAport home page.

Landsat

Since 1972, Landsat satellites in sun synchronous, polar orbit have provided global coverage of multi spectral data for monitoring land resources. Currently Landsat-7 and Landsat-5 are operational and Landsat-4 is in stand-by mode. Landsat data collected within the past 10 years can be purchased from EOSAT, 301-552-0500, or a formal agreement to receive data directly and distribute it can be negotiated with EOSAT. Data older than 10 years can be obtained from the United States Geological Survey (USGS).

The Landsat Program was redefined by Congress in 1992 and amended by Presidential Decision Directive/NSTC-3 in May 1994. Preservation of the long continuous record of earth surface observations and continuation of Landsat data acquisition were identified in these laws as critical to land surface monitoring and global change research. The National Aeronautics and Space Administration (NASA) and the USGS jointly manage the Landsat program. Landsat is part of the NASA's global change initiative, the Earth Observing System (EOS), which is administered by NASA's Earth Science Enterprise. The USGS manages the satellite operations and will perform the data processing, archiving and distribution. Landsat data make up the National Satellite Land Remote Sensing Data Archive maintained by USGS. Further information about Landsat is available via EMAIL, landsat@usra.edu, or at the Landsat home page.

For More Information

*A manufacturers list of APT, WEFAX, HRPT and GVAR receiving equipment and components is available on this website. A "User's Guide for Building and Operating Environmental Satellite Receiving Stations" is available to educators, individuals and others who may be considering establishing a meteorological satellite receiving station. This publication covers the basic requirements for a low-cost station to receive the APT and WEFAX services, and background for the high resolution HRPT and GVAR services. Examples of the types of data received, are shown. Requests should be Emailed to the Satellite Information Team (below), or requested from:

Direct Readout Coordinator
NOAA NESDIS E/SP3
Attn: D. Robertson
FOB 4, Room 3320
5200 Auth Road
Suitland, MD 20746-4304 USA