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AVHRR Leads-ARI Polar Gridded Brightness Temperatures

Lead Image


Summary

The AVHRR Leads-ARI Polar Gridded Brightness Temperatures data set contains Advanced Very High Resolution Radiometer images for use by scientists interested in lead dynamics and global climate change. The data set consists of AVHRR images compiled as part of the Arctic Leads Accelerated Research Initiative (Arctic Leads ARI). The data set includes images for three years for the Beaufort, Chukchi, East Siberian, Barents, Kara, East Greenland, and Laptev Seas.

Quick-look, hard copies provided by the National Ice Center of AVHRR images were used to select images for inclusion in the data set. Raw digital data for the selected images were converted to albedo and brightness temperature, and the compiled data were gridded to a stereographic projection. The data set primarily consists of image files and graphics files. It also includes browse images and files with satellite nadir track positions. Data are available via FTP.

The Arctic Leads ARI data set project was supported by the Office of Naval Research (ONR) under Program Element No. 61153N with Dr. Thomas Curtin as Program Manager. Distribution of the data set is supported by NASA under its Earth Observing System Data and Information System (EOSDIS) program. For more information about the data set, please contact NSIDC User Services.

For more information, please refer to the Arctic Leads ARI Project Description guide document and Instrument and Platform document.

Table of Contents

1. Data Set Overview
2. Investigators
3. Theory of Measurements
4. Equipment
5. Data Acquisition Methods
6. Observations
7. Data Description
8. Data Organization
9. Data Manipulations
10. Errors
11. Notes
12. Application of the Data Set
13. Future Modifications and Plans
14. Software
15. Data Access
16. Output Products and Availability
17. References
18. Acronyms and Abbreviations
19. Document Information

1.Data Set Overview

Data Set Identification

AVHRR Leads-ARI Polar Gridded Brightness Temperatures

Data Set Introduction

Although leads comprise only one percent of the surface area of the arctic ice pack, they contribute as much as half of the heat and moisture exchange at the surface during the winter. Formed as a result of ice pack deformation, leads grow anywhere from a few meters to a few kilometers wide. The fluxes generated by leads influence the atmosphere by:

Wolfe et al. (1993)

Using hard copies of AVHRR images provided by the Joint Ice Center (now the National Ice Center), the investigators evaluated image data for a given satellite pass, ranked each image for areal and cloud coverage, and compiled the image evaluations in monthly spreadsheets. The investigators then used the image evaluation spreadsheets to select digital imagery from the Satellite Data Services Division (SDSD) of NOAA's National Environmental Satellite Data and Information Service (NESDIS).

To facilitate comparisons of SSM/I and AVHRR data, the selected imagery was warped to the same projection and aligned with the same grid as that used by NSIDC for arctic SSM/I brightness temperature data. The projection is polar stereographic with the map plane at 70 degrees north. Two grids were used to cover most of the Arctic. The raw data were converted to albedo and brightness temperature following procedures similar to those outlined in Kidwell (1986) and Lauritson et al. (1979).

The AVHRR Leads-ARI Polar Gridded Brightness Temperatures data set consists of imagery for 1988, 1989 and 1992. The grids completely cover the Beaufort, Chukchi, East Siberian, Barents, and Kara Seas, and partially covers the East Greenland and Laptev Seas. The data set consists of image files containing the satellite data, graphics files containing the coastline overlays used with the satellite data, browse images containing subsampled images, and data files with nadir track positions.

Related Data Sets

2.Investigators

Investigators' Names and Titles

The Principal Investigators for the data set project of the Arctic Leads ARI were:

Florence M. Fetterer, National Snow and Ice Data Center

Jeffrey D. Hawkins, Meteorologist, Prediction Systems Branch, Naval Research Laboratory, Marine Meteorology Division

Title of Investigation

AVHRR Leads-ARI Polar Gridded Brightness Temperatures. For a description of the Arctic Leads Accelerated Research Initiative (ARI), please see the Project Description guide document.

Contact Information

NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449  USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
e-mail: nsidc@nsidc.org

3.Theory of Measurements

The AVHRR is a radiometer carried aboard polar orbiting satellites. It senses and measures the intensity of passive radiant energy emitted and reflected by the Earth and its atmosphere. Hastings and Emery (1992) summarize the historical development of the AVHRR sensor hardware and provide an overview of its data collection capabilities. For more information on the theory of AVHRR measurements, please refer to the Arctic Leads ARI Instrument document.

4.Equipment

The AVHRR sensor is a broad band, cross-track scanning instrument that senses in the visible, near-infrared, and thermal infrared portions of the electromagnetic spectrum. Depending on the model, the AVHRR is a four or five channel scanner. It has flown continuously on the NOAA polar orbiting series of satellites since 1978 and provides pole-to-pole on board collection of data from all channels. The satellite orbits the Earth approximately 14 times per day at an orbital inclination of about nine degrees. Each pass covers a 2399-km wide swath. The average instantaneous field of view (IFOV) of 1.4 milliradians yields a LAC/HRPT ground resolution of approximately 1.1 km at the satellite nadir from the nominal orbit altitude of 833 km.

A table listing the wavelengths of each of the AVHRR channels is available. Another table identifies the NOAA satellites that carried the AVHRR during the period of interest to the Leads ARI. For a complete description of the AVHRR mission objectives, collection environment, operation principles, measurement geometry, calibration and specifications, please see the Arctic Leads ARI Instrument document.

5.Data Acquisition Methods

The following description of the Arctic Leads ARI data acquisition methods are summarized from Fetterer and Hawkins (1991).

AVHRR Data Availability

AVHRR data formerly archived by the Satellite Data Services Division (SDSD) of NOAA's National Environmental Satellite Data and Information Service (NESDIS), are now archived by the Climate Services Division (CSD) of the National Climatic Data Center (NCDC) at NESDIS in Asheville, North Carolina. The data can be obtained in three forms:

HRPT direct readout data are continuously broadcast from the satellite and are available for areas within a ground station mask. For instance, the Gilmore Creek, Alaska ground station receives HRPT data covering the Beaufort, Bering, Chukchi, and East Siberian Seas. LAC data are HRPT data that have been recorded on board the satellite for playback when the satellite is within range of a Command and Data Acquisition (CDA) station. Up to ten minutes of LAC data can be recorded during each orbit. GAC data are reduced resolution data acquired during an entire orbit and stored for playback on command. A resolution cell size of about four km at nadir makes GAC unsuitable for most Arctic Leads ARI purposes.

Image Evaluation and Selection

Hard copy prints of the AVHRR imagery were usually made using channel 4 (IR) during the arctic winter and channel 2 (visible) in summer. When the investigators visited SDSD in March 1990, they found the hard copy archive to be of limited use because it contained very few LAC and HRPT hard copies and no latitude/longitude grids. As an alternative to the SDSD archive, the investigators used an archive of hard copy AVHRR images at the Navy/NOAA Joint Ice Center (now the National Ice Center), which uses AVHRR as a primary tool for ice analysis and forecasting and makes a hard copy of almost every HRPT and LAC pass.

Images are from one to three frames long. Each frame includes about three minutes of data covering about nine degrees of latitude. An ascending pass starting at 70 degrees over Alaska would cover just the Beaufort Sea if the resulting image were only one frame long. If the image were three frames in length, the same pass would cover the Beaufort, Chukchi, East Siberian, Laptev, and some of the central Arctic.

Using the hard copies provided by the Joint Ice Center, image data for a given satellite pass were evaluated to determine how much of each sea was covered by the pass and how much of the image was covered by clouds. The investigators examined all images but eliminated from consideration images that were clearly of no value to the Arctic Leads ARI. The investigators noted the time and orbit printed on each hard copy as well as the seas covered by the image. They then ranked each image on a scale of one to five for degree of cloud cover and areal coverage. For example, a rank of "5-2" for the Beaufort Sea would mean that 100 percent of the image is cloud-free but only about 40 percent of the Beaufort is covered by the image.

The investigators then compiled their image evaluations in monthly spreadsheets, which they used to select imagery for inclusion in the data set. Early evaluations revealed a need to change the original data selection goals of 20 images per month and complete coverage of the Arctic every three days. Limited areal coverage outside the Beaufort Sea and extensive cloud cover as well as budgetary limitations mandated the change. Initially, the investigators selected images in an attempt to cover the entire Arctic with evenly spaced temporal intervals. After recognizing the extent of could cover in the images, they elected to take advantage of the available data by selecting approximately 10 images of leads per month representing several sequential cloud free days. Unless shorter passes were part of time sequences in which leads could clearly be seen, the investigators generally favored passes covering large areas over shorter, relatively cloud free passes.

6.Observations

Data Notes

This field is intentionally left blank.

Field Notes

The Arctic Leads ARI included a field experiment (LeadEx) in the Beaufort Sea to study the effect of open leads on the polar ocean and atmosphere. During March and April of 1992, data were collected from a base camp northeast of Prudhoe Bay, Alaska and at several nearby leads using remote and surface based sensors. A list of LeadEx Instruments and Parameters identifies the meteorological instruments used and parameters measured during the LeadEx field operations.

7.Data Description

Spatial Characteristics

Spatial Coverage

The data set covers the Beaufort, Chukchi, East Siberian, Barents, and Kara Seas, and some of the East Greenland and Laptev Seas.

Spatial Coverage Map

ARI Grids Map

Spatial Resolution

Because the sensor response is not linear with temperature, its resolution varies with channel and the temperature of the observed scene. At an altitude of 833 km and with an IFOV of 1.4 milliradians, the nominal AVHRR sensor resolution is 1.1 km at nadir and about four km at the scan limbs (at a satellite scan angle of 55.4 degrees from nadir). There are 2048 samples from each channel across each scan. The sensor swath width is about 2900 km, or 26 degrees of latitude. Data are recorded with 10-bit precision. The radiometer is operable between approximately -80 degrees C to 40 degrees C. The brightness temperature resolution of the instrument varies with temperature and is about .12 degrees C.

Projection

Imagery was warped to a ground-plane projection using position tie points embedded in the scan lines of the Level 1B data. Tie points were calculated using Brouwer mean orbital elements from orbital information provided by the North American Air Defense Command (NORAD). Tie point accuracy depended on factors such as satellite tracking accuracy, length of time since an update, and the satellite clock accuracy. To improve the navigational accuracy given by the NESDIS tie points, each image was displayed with a graphic overlay of the coastline. For the images from 1988 and 1989, the overlay from the World Data Bank (WDB) II was used. For the 1992 images, the World Vector Shoreline (WVS) data base was used. If any coastline visible in the image did not match the graphic display, the image was shifted to make the best possible match. Often a perfect match was not possible everywhere. This was especially true along the north coast of Greenland, where the WVS is itself in error by several kilometers.

Grid Description

To facilitate comparisons of SSM/I and AVHRR data, the Arctic Leads ARI imagery was warped to the same projection and aligned with the same grid as that used by NSIDC for arctic SSM/I brightness temperature data. The investigators considered grids with other projections including the Fleet Numerical Meteorology and Oceanography Center (FNMOC) atmospheric fields and Polar Ice Prediction System (PIPS) ice forecasts, which are available on grids with a polar projection true at 60 degrees north. They decided, however, that these and other grids were relatively coarse in comparison with the SSM/I grid.

The projection is polar stereographic with the map plane at 70 degrees north. Distortion at the pole is three percent. The north polar SSM/I grid is aligned with the SSM/I grid and covers most of the Arctic with AVHRR data. Of the two grids depicted in the Pacific and European Grids Map, the Pacific grid covers the Beaufort, Chukchi, and East Siberian Seas while the European grid covers the Barents, Kara, and some of the East Greenland and Laptev Seas. The investigators decided that increasing the coverage of the Barents Sea was preferable to covering all of the Laptev. Because very few Laptev Sea images were available and the grid size was already cumbersome in terms of data storage requirements, the investigators rejected the option of enlarging the grid to cover Laptev.

The Pacific and European grids are each 2250 x 2800 pixels. The pixel size is one km. There is a pixel border at 135 west on the Pacific grid and one at 45 degrees east on the European grid. These correspond to the alignment of cells in the SSM/I grid. Therefore, 25 x 25 AVHRR pixels will fit within each of the 25-km SSM/I grid cells. (See the figure that depicts the relationship between SSM/I grid coordinates and Arctic Lead ARI grid sample, line indexes.)

Two coordinates conversion programs are available:

Temporal Characteristics

Temporal Coverage

The data set consists of imagery for all months of 1989 and 1992, and all months of 1988 except February, March and May. For 1988, coverage is limited and there are no images for February, March or May. For 1989, Beaufort Sea and Chukchi Sea coverage is good except in the cloudiest month of August when Kara Sea and Barents Sea coverage is scant. For 1992, coverage in March, August, September and October is scant, with four or fewer images each month.

Temporal Coverage Map

A temporal coverage map is not included in this document.

Temporal Resolution

The data set includes approximately 10 to 20 images per month. For 1988 and 1992, the data set includes approximately 10 images per month while for 1989, there are about 20 images per month. However, some months have many more than the average, and some have many fewer.

Data Characteristics

Parameter/Variable

The data set consists of brightness temperature and albedo data. The parameters measured during the Arctic Leads ARI field experiment (LeadEx) in the Beaufort Sea in the spring of 1992 are identified in a list of LeadEx Instruments and Parameters.

Variable Description/Definition

This section is not relevant to this document and is intentionally left blank.

Unit of Measurement

Brightness temperature data are presented in degrees Celsius, and albedo is presented as percent albedo.

Data Source

AVHRR data in the data set were retrieved from digital tape archived by Satellite Data Services Division (SDSD) of the NOAA National Environmental Satellite Data and Information Service (NESDIS) in Camp Springs, Maryland.

Data Range

This section is not relevant to this document and is intentionally left blank.

Sample Data Record

A sample data record of raw binary data is too large to present here. Please refer to the data format section for information about the contents of the images files and the availability of browse images. The following is a very small subsample of an AVHRR image from the data set showing a large lead off Banks Island.

Sample Image
AVHRR Image Subsample

The sample is a channel 4 image from a pass made December 14, 1989 and is a subsample of an image presented in Fetterer et al. (1993).

8.Data Organization

Data Granularity

A data granule is the smallest aggregation of data that can be independently described, inventoried, or retrieved. An individual image constitutes a granule in the AVHRR Leads-ARI Polar Gridded Brightness Temperatures data set.

Data Format

The data set consists of compressed UNIX files including image files, graphics files, binary nadir track files, orbital element ASCII data files, and browse image files.

The image files contain the AVHRR satellite data. Each displayable file created on the I2S system has the extension .img. The images are raw binary files of short integer data and are 2250 x 2800 pixels in size. Image files were written in sample, line, and band format, although each band of the AVHRR data is given a separate file. At NSIDC, a VAX system and VAX DIGITAL Command Language backup command were used to write files from the NOARL system to 6250 bpi tapes for NSIDC.

Please refer to the list of graphics files and sample image files. The file naming convention is illustrated by file p13jan89_2124_c1s.img as follows:

	channel 1 of an image taken	(p13jan89_2124_c1s.img)
January 13, 1989 at 2124 GMT (p13jan89_2124_c1s.img)
and mapped to the Pacific Grid (p13jan89_2124_c1s.img)
for short integer data (p13jan89_2124_c1s.img)

The graphics files contain the WDB and WVS coastline overlays. The graphics files are full resolution (2250 x 2800 pixels) and are named as follows:

	Contents		European grid	Pacific grid
------------------------------------------------------
latitude/longitude egrid.img pgrid.img
coastline overlays emap.img pmap.img
land masks emask.img pmask.img

For most image files, there are corresponding nadir track files (for example, e06jan89_0913_trk.image) that contain a plot of the nadir track for the given image. An orbital element data file contains tracking information about the satellite pass during which the imagery was acquired, along with nadir track positions every ten seconds. (See the sample orbital element data file.)

The data set also includes selected browse image files for selected 1989 AVHRR scenes. The browse images, which are in Hierarchical Data Format (HDF), are intended to provide potential data set users with information about AVHRR scenes prior to making a data request. The browse images illustrate each scene's area of coverage, highlight leads within the scene, and provide initial estimates of geophysical parameters (e.g., albedo or brightness temperature). Each browse image provides an easily-distributed scene derived from the image data and requires minimal manipulation of the raw sensor values.

The browse images are derived from original data from 1989. All browse images are 450 x 560 pixels and 8-bit per pixel. Except for the summer season when melt degrades the ability of the thermal channel to discriminate leads, the browse images are from channel 4 of the AVHRR. For the summer season, the images are from channel 2 (near-infrared). The "summer" set includes images from May, June, July, and August. Browse images from all other months are referred to as "winter" images. The archive consists of four subsets of the original data:

A detailed description of the data processing involved in the derivation of the browse images is available. An alphabetical list of all data set files in the AVHRR Leads-ARI Polar Gridded Brightness Temperatures data set is also available.

9.Data Manipulations

Formulae

Derivation Techniques and Algorithms

For the full resolution images, the raw data were converted to albedo and brightness temperature following procedures similar to those outlined in Kidwell (1986) and Lauritson et al. (1979).

Data Processing Sequence

Processing Steps

Data from channels 1 and 2 were processed by converting raw counts to albedo using a straight line approximation based on pre-launch calibration. Albedo was expressed as a percentage of that for a perfectly reflecting Lambertian surface illuminated by an overhead sun. Each output count in the processed data was 0.1 percent. For example a count of 500 would equal 50 percent albedo.

Raw count values for channels 3, 4, and 5 were converted to radiances using a straight line approximation to calibration from onboard observations of space and an internal blackbody. Each possible raw count value of zero to 1023 on the NOAA Level-1B data tape was matched with a radiant energy value in a look-up table. Energy was then converted to brightness temperature based on the inverse of Plank's function.

Data processing steps are described in detail in Fetterer and Hawkins (1993).

Processing Changes

This section is not relevant to this document and is intentionally left blank.

Calculations

Brightness temperatures were converted to output counts using the equation:

N = (10(K-273.16)) + 500, where:
N = output count value
K = brightness temperature (degrees Kelvin)

Output count values are stored in short integer (16-bit) form. Count values can be converted to degrees Kelvin using:

K = ((N-500)/10) + 273.16

or to degrees Celsius using:

C = (N-500)/10

The result is 0.1 degree per count, with a count of 500 equal to 0 degrees C. If the temperature observed is less than -50 degrees C, the count value will be negative.

NOTE: If the count values of 16-bit processed imagery are to be displayed using hardware with an 8-bit deep image plane, the 16-bit images must be scaled to 8-bit images.

Special Corrections/Adjustments

For channels 1 and 2, no corrections were made for sun angle or atmospheric effects. A nonlinear correction to temperature was applied to channels 3, 4, and 5 using the coefficients for each channel given in periodic NOAA updates and Lauritson et al. (1979).

The program that created the nadir track listings was modified so that a nadir track could be created even if it fell outside the image.

Calculated Variables

The raw data were converted to albedo and brightness temperature using the methods described above.

Graphs and Plots

A detailed description of the data processing involved in the derivation of the browse images is available.

10.Errors

More information about the quality of the data set imagery is available in Fetterer and Hawkins (1993).

11.Notes

Because relatively cloud free images were selected for the data set, it is not particularly well suited for cloud studies. For 1988, coverage is limited and there are no images for February, March or May.

12.Application of the Data Set

The relevance of ice lead width and width distribution to flux calculations in sea ice and climate models has been addressed (Maslanik and Key 1995) and AVHRR imagery has been used to study lead pattern formation in the Beaufort Sea in response to wind forcing (Walter and Overland 1993). Lindsay and Rothrock (1994) used the AVHRR Leads-ARI Polar Gridded Brightness Temperatures data set to estimate the surface temperature of arctic sea ice. Lindsay and Rothrock (1995) derived lead orientation and width statistics with the data set. The data set could also be used to:

Hastings and Emery (1992) provide an overview of general AVHRR data applications.

13.Future Modifications and Plans

There are no plans to modify the AVHRR Leads-ARI Polar Gridded Brightness Temperatures data set.

14.Software

Software Description

Copies of the following coordinates conversion programs are available:

The Cloud and Surface Parameter Retrieval (CASPR) system is a toolkit that can be used to retrieve a variety of surface and cloud parameters from AVHRR data.

Software Access

This field is intentionally left blank.

15.Data Access

Data are availavble via FTP.

Contact Information

NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449  USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
e-mail: nsidc@nsidc.org

Data Center Identification

National Snow and Ice Data Center (NSIDC)

Data Center Status/Plans

NSIDC has no plans to expand the AVHRR Leads-ARI Polar Gridded Brightness Temperatures data set.

16.Output Products and Availability

An alphabetical list of all data set files is available. For more information about output products and availability, please contact NSIDC User Services.

17.References

Note: Information in this document was derived from (Fetterer et al. 1991) and (Fetterer et al. 1993)

Fetterer, F. M., and J. D. Hawkins. 1991. An AVHRR data set for the arctic leads ARI. Naval Oceanographic and Atmospheric Research Laboratory, Technical Note 118, 61 p.

Fetterer, F. M., and J. Hawkins. 1993. Data set of arctic AVHRR imagery for the study of leads. Annals of Glaciology. 17:394-404.

Hastings, D. A., and W. J. Emery. 1992. The advanced very high resolution radiometer (AVHRR): a brief reference guide. Photogrammetric Engineering & Remote Sensing 58(8):1183-1188.

Kidwell, K. B. 1986. NOAA Polar Orbiter Data Users Guide. U.S. Department of Commerce. National Oceanic and Atmospheric Administration, Satellite Data Services Division, Washington, D.C. Revised December 1991.

Kidwell, K. B. 1995. NOAA Polar Orbiter Data Users Guide: NOAA Polar Orbital Environmental Satellites (POES). U.S. Department of Commerce. National Oceanic and Atmospheric Administration, Satellite Data Services Division, Washington, D.C. Revised January 1995.

Lauritson, L., G. J. Nelson, F. W. Porto. 1979. Data extraction and calibration of TIROS-N/NOAA radiometers. NOAA Technical Memorandum NESS-107. National Environmental Satellite Service, Washington, D.C.

Lindsay, R. W., and D. A. Rothrock. 1994. Arctic sea ice surface temperature from AVHRR. Journal of Climate 7(1):174-183.

Lindsay, R. W., and D. A. Rothrock. 1995. Arctic sea ice leads from advanced very high resolution radiometer images. Journal of Geophysical Research 100(C3):4533-4544.

Maslanik, J. A., and J. Key. 1995. On treatments of fetch and stability in large-area estimates of sensible heat flux over sea ice. Journal of Geophysical Research 100(C3):4573-4584.

Walter, B. A., and J. E. Overland. 1993. The response of lead patterns in the Beaufort Sea to storm-scale wind forcing. Annals of Glaciology 17:219-226.

Wolfe D. E., D. Ruffieux, C. W. Fairall. 1993. The 1992 arctic leads experiment: an overview of the meteorology. Arctic research of the United States 7:24-28.

18.Acronyms and Abbreviations

The following acronyms and abbreviations are used in this document.

ARI Accelerated Research Initiative
AVHRR Advanced Very High Resolution Radiometer
C Celsius
CDA Command and Data Acquisition
DMSP Defense Meteorological Satellite Program
EOSDIS Earth Observing System Data and Information System
FNMOC Fleet Numerical Meteorology and Oceanography Center
GAC Global Area Coverage
GMT Greenwich Mean Time
HRPT High Resolution Picture Transmission
IFOV Instantaneous Field of View
IR Infrared
JIC Joint Ice Center
K Kelvin
km kilometer
LAC Local Area Coverage
LST Local Solar Time
NASA National Aeronautics and Space Administration
NOAA National Oceanic and Atmospheric Administration
NOARL Naval Oceanographic and Atmospheric Research Laboratory
NSIDC National Snow and Ice Data Center
NEdT Noise Equivalent Differential Temperature
NESDIS National Environmental Satellite Data and Information Service
NESS National Environmental Satellite Service
NORAD North American Air Defense Command
ONR Office of Naval Research
PIPS Polar Ice Prediction System
POES Polar Orbiting Environmental Satellites
RASS Radio Acoustics Sounding System
SDSD Satellite Data Services Division
SSM/I Special Sensor Microwave Imager
TIROS Television and Infrared Observation Satellite
URL Uniform Resource Locator
WDB World Data Bank
WVS World Vector Shoreline

19.Document Information

Revision Date: 24 October 2011
Review Date: 31 August 1995
Document ID: nsidc-0026

Citation:

We kindly request that you cite the use of this data set in a publication using the following citation example. For more information, see our Use and Copyright Web page.

Fetterer, F., and J. Hawkins. 1995. AVHRR leads-ARI polar gridded brightness temperatures. Boulder, CO: National Snow and Ice Data Center. Digital media.

Document Curators: NSIDC Writers
Document URL:
http://nsidc.org/data/docs/daac/nsidc0026_arctic_leads_ari.gd.html