Identification_Information:
Citation:
Citation_Information:
Originator:
U.S. Geological Survey (USGS), Earth Resources Obsevation System (EROS)
Publication_Date: 19941130
Title: Advanced Very High Resolution Radiometer (AVHRR)
Geospatial_Data_Presentation_Form: remote-sensing image
Publication_Information:
Publication_Place: Sioux Falls, SD
Publisher:
U.S. Geological Survey (USGS), Earth Resources Observation System (EROS)
Online_Linkage:
Description:
Abstract:
In 1961, the Department of Commerce was directed by Congress to establish and operate a meteorological satellite system. This system was to provide for the continuous observation of worldwide meteorological conditions from space and to report and process the data obtained for use in weather forecasting.
The Advanced Very High Resolution Radiometer (AVHRR) sensor is a broad-band 4- or 5-channel scanning radiometer, sensing in the visible, near-infrared, and thermal infrared portions of the electromagnetic spectrum. Beginning in 1978, this sensor has been carried on the National Oceanic and Atmospheric Administration's (NOAA) Polar Orbiting Environmental Observation Satellites-N (TIROS-N) series.

The normal operating mode of the satellite is for direct transmission of AVHRR data to Earth continuously in real time. This direct transmission is called High Resolution Picture Transmission (HRPT). In addition to the HRPT mode, about 11 minutes of data may be selectively recorded per orbit, by recorders on board the satellite for later playback. These recorded data are referred to as Local Area Coverage (LAC) data. he LAC data may be recorded over any portion of the world as selected by NOAA/National Environment Satellite, Data and Information Service (NESDIS) and played back on the same orbit as recorded or during a subsequent orbit.

Purpose:
The AVHRR Data Set provides long term, global data of land surface parameters with high temporal frequency coarse resolution for studying the Earth as an integrated system.
The objective of the AVHRR instrument provides radiance data for investigation of clouds, land-water boundaries, snow and ice extent, ice or snow melt inception, day and night cloud distribution, temperatures of radiating surfaces, and sea surface temperature. It is an integral member of the payload on the advanced Television and Infrared Observation Satellite-N (TIROS-N) spacecraft and its successors in the NOAA series and, as such, contributes data required to meet a number of operational and research-oriented meteorological objectives.

Supplemental_Information:
AVHRR data are raw data as received by the satellite and archived as Level-0. Level-1b data are raw data that have been quality controlled, assembled into discrete data sets, and appended with Earth location and calibration information (but not applied).
The LAC and HRPT data sets have been combined in this document since they have identical Level-1b formats and spatial resolutions.

The AVHRR Level-1b data represent a collection of data sets. Each data set contains one type of data for a discrete time period. Thus, there are separate AVHRR HRPT, LAC, and GAC data sets. Time periods are arbitrary subsets of orbits and may cross orbits (i.e., may contain data along a portion of an orbital track that includes the ascending node, the reference point for counting orbits). Generally, GAC data sets are available for corresponding time periods and usually have a 3- to 5-minute overlap between consecutive data sets.

Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 1978
Ending_Date: present
Currentness_Reference: ground condition
Status:
Progress: In work
Maintenance_and_Update_Frequency: Daily
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -180.0
East_Bounding_Coordinate: 180.00
North_Bounding_Coordinate: 90.00
South_Bounding_Coordinate: -90.0
Keywords:
Theme:
Theme_Keyword_Thesaurus: none
Theme_Keyword: digital image
Theme_Keyword: HRPT
Theme_Keyword: imagery
Theme_Keyword: Infrared
Theme_Keyword: LAC
Theme_Keyword: level 1b
Theme_Keyword: radiance
Theme_Keyword: raster
Theme_Keyword: satellite
Theme_Keyword: Visible
Place:
Place_Keyword_Thesaurus: none
Place_Keyword: Global
Temporal:
Temporal_Keyword_Thesaurus: none
Temporal_Keyword: TIROS-N 10/19/78 - 01/30/80
Temporal_Keyword: NOAA-6 06/27/79 - 03/05/83
Temporal_Keyword: NOAA-7 08/24/81 - 06/07/86
Temporal_Keyword: NOAA-8 06/20/83 - 10/31/85
Temporal_Keyword: NOAA-9 02/25/85 - 11/07/88
Temporal_Keyword: NOAA-10 11/17/86 - 09/16/91
Temporal_Keyword: NOAA-11 11/08/88 - 09/13/94
Temporal_Keyword: NOAA-12 09/01/91 - present
Temporal_Keyword: NOAA-14 12/30/94 - present
Access_Constraints: none
Use_Constraints:
Acknowledgement of the U.S. Geological Survey would be appreciated in products derived from these data.
Point_of_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:
U.S. Geological Survey (USGS) EROS Data Center
Contact_Person: Customer Services
Contact_Position: Customer Services Representative
Contact_Address:
Address_Type: mailing and physical address
Address:
U.S. Geological Survey (USGS) EROS Data Center
City: Sioux Falls
State_or_Province: SD
Postal_Code: 57198
Country: US
Contact_Voice_Telephone: (605) 594-6151
Contact_TDD/TTY_Telephone: (605) 594-6933
Contact_Facsimile_Telephone: (605) 594-6589
Contact_Electronic_Mail_Address: custserv@edcmail.cr.usgs.gov
Hours_of_Service: 0730 - 1615 CST
Contact_Instructions:
Security_Information:
Security_Classification_System: none
Security_Classification: Unclassified
Security_Handling_Description: none
Native_Data_Set_Environment: Unix
Data_Quality_Information:
Logical_Consistency_Report:
The AVHRR sensor was designed to view cold space and one or more internal warm blackbodies for each scan sequence while in orbit.
In general, radiometric calibration involves exposing a radiometer to sources of radiation that have been calibrated against primary or secondary standards and determining a relationship between the output of the radiometer and the intensity of the incident radiation (radiance).

All the radiometers flown on the NOAA/TIROS satellites undergo extensive prelaunch testing and calibration by their manufacturers to characterize their performance. The NESDIS independently analyzes the data from the prelaunch tests to determine the operating characteristics of the instruments, such as their signal-to-noise ratios, stability, linearity of response, and sensitivity. However, characteristics cannot be expected to be the same in orbit as they were before the launch. One reason is that the thermal environment varies with position in the orbit, causing sensitivities to vary orbitally. Also, instrument components age in the several years that usually elapse between the time of the prelaunch tests and launch, and the aging process continues during the two or more years the instrument typically operates in orbit. Therefore, the NOAA/TIROS radiometers have been designed to view cold space and one or more internal warm blackbodies as part of their normal scan sequences in orbit.

Completeness_Report:
As the spacecraft moves through its orbit, the expected angular distance between the nadir of adjacent LAC/HRPT scans is approximately 0.0296 degrees of arc, or 3.2914 kilometers, as measured from the center of the Earth. This actual value of the average angular distance can vary by up to about 0.1712 kilometer due to variations in satellite height, scan angle and other factors.
The instantaneous field of view (IFOV) for all channels is specified to be 1.3 +/- 0.1 milliradians.

Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report: None
Quantitative_Horizontal_Positional_Accuracy_Assessment:
Horizontal_Positional_Accuracy_Value: 5 kilometer
Horizontal_Positional_Accuracy_Explanation:
Precise georegistration positional accuracy of 1000 meter RMSE requires correlation of image features with accurately registered cartographic or image-based maps. A common practice is to use cartographic sources such as Digital Chart of the World (DCW) or hydrography data to extract easily identifiable features such as coastlines, water bodies, and rivers and to correlate them with the matching raw image locations using various techniques.
Lineage:
Source_Information:
Source_Citation:
Citation_Information:
Originator:
U.S. Geological Survey (USGS), Earth Resources Obsevation System (EROS)
Publication_Date: 19902003
Title: Advanced Very High Resolution Radiometer (AVHRR)
Geospatial_Data_Presentation_Form: map
Publication_Information:
Publication_Place: Sioux Falls, SD
Publisher:
U.S. Geological Survey (USGS), Earth Resources Observation System (EROS)
Source_Scale_Denominator: 1000000
Type_of_Source_Media: magnetic tape
Source_Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 19800210
Ending_Date: Unknown
Source_Currentness_Reference: ground condition
Source_Citation_Abbreviation: AVHRR
Source_Contribution: A graphical representation of the data swaths
Process_Step:
Process_Description:
The EDC's ADAPS flow for acquisitions and archiving begins with either direct HRPT reception or with re-broadcast of DOMSAT LAC/GAC reception. Initial ingest of the data reformatting includes archive, and creation of browse quick looks and cartridge tapes.
The NOAA AVHRR processing flow begins with sensor data receipt by the CDA stations (Wallops Island, Virginia, and Gilmore Creek, Alaska) where the data are re-broadcast via communications satellites to NOAA/NESDIS in Suitland, Maryland. The ephemeris data are accessed through the Gridded Earth Location Determination System (GELDS) software for generation of Level-1b production.

The EDC ADAPS systematic georegistration process references AVHRR data to the Earth's surface. Through modeling the position and attitude of the TIROS satellite platforms and the canning geometry of the AVHRR sensor, geometric distortions can be minimized. The position of the satellite is determined by an orbital model updated by ephemeris data received daily from NAVY Space Surveillance. The AVHRR sensor model characterizes the non-linear scanning of the sensor mirror. A refinement to the sensor model accounts for the displacement in longitude due to the rotation of the Earth under the satellite. All modeling is referenced to the time of acquisition. As the satellite clock time drifts, a delta time adjustment is applied. Collectively, these models comprise the geometric correction model in ADAPS. The positional accuracy of a systematic georegistration is approximately 5,000 meter, root-mean-square-error (RMSE).

Precise georegistration positional accuracy of 1000 meter RMSE requires correlation of image features with accurately registered cartographic or image-based maps. A common practice is to use cartographic sources such as Digital Chart of the World (DCW) or hydrography data to extract easily identifiable features such as coastlines, water bodies, and rivers and to correlate them with the matching raw image locations using various techniques. The correlation process determines specific adjustments to be applied to the time, roll, and yaw parameters of the orbital model. The EDC ADAPS uses a variety of techniques depending upon the geographic location of the imagery and the volume of data to be processed.

Source_Used_Citation_Abbreviation: AVHRR
Process_Date: Not complete
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:
U.S. Geological Survey (USGS) EROS Data Center
Contact_Person: Customer Services
Contact_Position: Customer Services Representative
Contact_Address:
Address_Type: mailing and physical address
Address:
U.S. Geological Survey (USGS) EROS Data Center
City: Sioux Falls
State_or_Province: SD
Postal_Code: 57198
Country: US
Contact_Voice_Telephone: (605) 594-6151
Contact_TDD/TTY_Telephone: (605) 594-6933
Contact_Facsimile_Telephone: (605) 594-6589
Contact_Electronic_Mail_Address: custserv@edcmail.cr.usgs.gov
Hours_of_Service: 0730 - 1615 CST
Contact_Instructions:
Cloud_Cover: Unknown
Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Raster
Raster_Object_Information:
Raster_Object_Type: Pixel
Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Local:
Local_Description:
The AVHRR sensor provides a global (pole-to-pole) onboard collection of data from all spectral channels. The 110.8-degree scan equates to a swath width of 27.2 degrees at the Equator centered on the subsatellite track. This swath width is greater than the 25.3-degree separation between successive orbital tracks, providing overlapping coverage (side-lap). The satellite orbits the Earth 14 times each day from 833 kilometers above its surface.
Local_Georeference_Information:
The IFOV of each channel is approximately 1.4 milliradians leading to a resolution at the satellite subpoint of 1.1 kilometers for a nominal altitude of 833 kilometers. The scanning rate of the AVHRR sensor is 360 scans per minute. The time within each scan line of AVHRR data represents IFOV 1. These data provide continuous transmission for the HRPT data and selectively recorded LAC data.
Entity_and_Attribute_Information:
Overview_Description:
Entity_and_Attribute_Overview:
Depending on the instrument, there are four or five channels, which measure wavelengths, as outlined previously in the Summary of Parameters. Other parameters appended include calibration coefficients, Earth location, time code, quality indicators, solar zenith angles, and telemetry.
Each LAC data set contains an individual satellite recorder playback (up to 11 minutes of recorded HRPT data). Each HRPT data set contains the HRPT data from a CDA contact. Data within each LAC/HRPT data set are arranged in chronological order with one scan contained in two physical records. Each record contains 7,440 bytes written in binary format.

The time code consists of the year, day of year, and greenwich mean time (GMT) time of day in milliseconds. The year is contained in the first 7 bits of the first two bytes, the 9-bit day of year is right-justified in the first two bytes, and the 27-bit millisecond GMT time of day is right-justified in the last four bytes. All other bits are zero. The time code always has the same format for all Level-1b data sets.

The quality indicators are contained in four bytes. The first byte contains the status of detected conditions during processing and the last three bytes contain Data Acquisition and Control Subsystems (DACS) quality indicators. If the bit is set to one or the on position, then the condition is true.

The calibration coefficients consist of slope and intercept values for each of the five channels. The use of these coefficients is described in Section 3.3 of the "NOAA Polar Orbiter Data User's Guide".

A fixed number of zenith angles and Earth location points are appended to each scan. However, only the first n zenith angles and the first n Earth location points have meaningful values (n is defined in byte 53). A maximum of 51 points is possible in a scan. There are 2,048 points in a LAC/HRPT scan line. However, the solar zenith angles and Earth location data (latitude and longitude) are sampled every 40 points starting at the twenty-fifth point (25, 65, 105, ..., 1945, 1985, 2025). There are 51 possible solar zenith angles and Earth location values for each scan line. Each zenith angle requires one byte (stored as degrees by 2). The latitude and longitude values are each stored in two-byte fields in 128ths of a degree (east positive).

The telemetry data contain information which may be used to compute calibration coefficients when these are not included in the data. The telemetry data are stored in 140-byte units. The first 103 10-bit words are packed three 10-bit words in four-bytes, right justified. The last four-byte group contains one 10-bit word with 20 trailing bits. All unused bits are set to zero. The contents of these 103 words are contained in Table 3.1.2.1-3 of the "NOAA Polar Orbiter Data User's Guide", which is the entire HRPT minor frame format. For more information, refer to NOAA Technical Memorandum NESS 107 entitled, "Data Extraction and Calibration of TIROS-N/NOAA Radiometers".

The LAC/HRPT video data consist of five readings (one for each channel) for each of the 2,048 points in a scan. They are packed as three 10-bit samples in four bytes, right-justified. The last four-byte group contains two 10-bit samples with 10 trailing zero bits. The first two bits of each four-byte group are zero. The 10,240 samples (2,048 points by 5 channels) are ordered scan point 1 (Channel 1, 2, 3, 4, 5), scan point 2 (Channel 1, 2, 3, 4, 5), and so forth. For TIROS-N, NOAA-6, NOAA-8, and NOAA-10, there is no sensor for Channel 5 so Channel 4 data are repeated in the Channel 5 position. The video data are stored in 2's complement form.

The 16-bit unpacked format for full copy LAC/HRPT data has the same format as the "packed" data described above except for the video data. The video data values for each channel are contained in the 10 least significant bits and the six most significant bits are zero filled.

Entity_and_Attribute_Detail_Citation: NOAA Polar Orbiter Data User's Guide
Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:
U.S. Geological Survey (USGS) EROS Data Center
Contact_Person: Customer Services
Contact_Position: Customer Services Representative
Contact_Address:
Address_Type: mailing and physical address
Address:
U.S. Geological Survey (USGS) EROS Data Center
City: Sioux Falls
State_or_Province: SD
Postal_Code: 57198
Country: US
Contact_Voice_Telephone: (605) 594-6151
Contact_TDD/TTY_Telephone: (605) 594-6933
Contact_Facsimile_Telephone: (605) 594-6589
Contact_Electronic_Mail_Address: custserv@edcmail.cr.usgs.gov
Hours_of_Service: 0730 - 1615 CST
Contact_Instructions:
Resource_Description: AVHRR
Distribution_Liability:
Although these data have been processed successfully on a computer system at the U.S. Geological Survey, EROS Data Center, no warranty expressed or implied is made by the Geological Survey, EDC regarding the utility of the data on any other system, nor shall the act of distribution constitute any such warranty. Use of trademarks or formats does not constitute endorsement by the U.S. Geological Survey. There are no copyright restrictions on the use, redistribution, or further processing of this data.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: ASCII
Digital_Transfer_Option:
Offline_Option:
Offline_Media: 8 mm cartridge tape
Recording_Capacity:
Recording_Density: 2 gigabytes
Recording_Density_Units: bits per inch
Recording_Format: ASCII
Compatibility_Information: UNIX, PC
Digital_Form:
Digital_Transfer_Information:
Format_Name: ASCII
Digital_Transfer_Option:
Offline_Option:
Offline_Media: 3480 cartridge tape
Recording_Capacity:
Recording_Density: 2 megabytes
Recording_Density_Units: bits per inch
Recording_Format: ASCII
Compatibility_Information: UNIX, PC
Fees:
Cartridge and cassette prices are available at:
Ordering_Instructions:
Dataset searching and ordering capabilities are available through EarthExplorer at:

Metadata_Reference_Information:
Metadata_Date: 19970811
Metadata_Review_Date: 19970808
Metadata_Future_Review_Date: 19971231
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:
U.S. Geological Survey (USGS) EROS Data Center
Contact_Person: Customer Services
Contact_Position: Customer Services Representative
Contact_Address:
Address_Type: mailing and physical address
Address:
U.S. Geological Survey (USGS) EROS Data Center
City: Sioux Falls
State_or_Province: SD
Postal_Code: 57198
Country: US
Contact_Voice_Telephone: (605) 594-6151
Contact_TDD/TTY_Telephone: (605) 594-6933
Contact_Facsimile_Telephone: (605) 594-6589
Contact_Electronic_Mail_Address: custserv@edcmail.cr.usgs.gov
Hours_of_Service: 0730 - 1615 CST
Contact_Instructions:
Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version: 1.0
Metadata_Time_Convention: local time
Metadata_Access_Constraints: none
Metadata_Use_Constraints: none
Metadata_Security_Information:
Metadata_Security_Classification_System: none
Metadata_Security_Classification: Unclassified
Metadata_Security_Handling_Description: none