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Nimbus High Resolution Infrared Radiometer Remapped Digital Data Daily L3, GeoTIFF

This data set (NmHRIR3G) consists of daily composites constructed from Nimbus 1, Nimbus 2, and Nimbus 3 satellites High Resolution Infrared Radiometer (HRIR) data for the region between 60° N and 60° S. Measurements were obtained during 1964, 1966, and 1969. Data are available as GeoTIFFs and browse images. For global composites in the HDF5 format, see the Nimbus High Resolution Infrared Radiometer Remapped Digital Data Daily L3, HDF (NmHRIR3H) data set.

Table of Contents

  1. Contacts and Acknowledgments
  2. Detailed Data Description
  3. Data Access and Tools
  4. Data Acquisition and Processing
  5. References and Related Publications
  6. Document Information

Citing These Data

The following example shows how to cite the use of this data set in a publication. For more information, see our Use and Copyright Web page.

Gallaher, David and G. Garrett Campbell. 2013. Nimbus High Resolution Infrared Radiometer Remapped Digital Data Daily L3, GeoTIFF, [indicate subset used]. Boulder, Colorado USA: NASA DAAC at the National Snow and Ice Data Center. doi:10.5067/NIMBUS/NmHRIR3G.

Overview

Platform

Nimbus 1 Satellite
Nimbus 2 Satellite
Nimbus 3 Satellite

Sensor

High Resolution Infrared Radiometer (HRIR)

Spatial Coverage

Northernmost Latitude: 60° N
Southernmost Latitude: 60° S
Easternmost Longitude: 180° E
Westernmost Longitude: 180° W

Spatial Resolution

Roughly 20 km

Temporal Coverage

Nimbus 1: 29 August to 21 September, 1964
Nimbus 2: 16 May to 14 November, 1966
Nimbus 3: 17 April to 30 November, 1969

Temporal Resolution

Daily

Parameters

Brightness Temperature

Data Format

GeoTIFF

Metadata Access

View Metadata Record

Data Access

See the Order Data page for a list of options.

1. Contacts and Acknowledgments

Investigators

David Gallaher
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449 USA

G. Garrett Campbell
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449 USA

Technical Contact

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

Acknowledgements

The Nimbus Data Rescue Project: Nimbus 1, 2, 3 was supported by NASA contract #NNG08HZ07C as a subtask to NSIDC at the University of Colorado. The PIs also wish to thank Alex Calder, Carl Gallaher, and Anna Schroeder for their contributions to this project.

2. Detailed Data Description

This data set (NmHRIR3G) consists of daily composites constructed from Nimbus 1, Nimbus 2, and Nimbus 3 satellites High Resolution Infrared Radiometer (HRIR) data for the region between for the region between 60° N and 60° S. These data files are GeoTIFF versions of the HDF-formatted equatorial projection file only from the Nimbus High Resolution Infrared Radiometer Remapped Digital Data Daily L3, HDF5 (NmHRIR3H) data set. See the NmHRIR3H documentation for details.

Please visit the Order Data page to see options for obtaining NmHRIR3G data files.

File Naming Convention

This section explains the file naming convention used for NmHRIR3G data files.

Example file name:
NmHRIR3H.downIR.[YYYY][MM][DD].G.tif

Refer to Table 2 for descriptions of the file name variables listed above.

Where:

Table 2. NmHRIR3G File Naming Convention
Variable Description
NmHRIR3G Product
DownIR To remove reflected light contamination in the raw data, only the descending half of the orbit was used.
YYYY Year
MM Month
DD Day
G Equatorial projection
.tif GeoTIFF

File Size

Data files are roughly 16 MB.

Spatial Coverage

  • Northernmost Latitude: 60° N
  • Southernmost Latitude: 60° S
  • Easternmost Longitude: 180° E
  • Westernmost Longitude: 180° W

Spatial Resolution

Roughly 20 km

Projection and Grid Description

Data are provided in a 20 km cylindrical equidistant projection. The grid was constructed by defining a 2000 east-west by 664 north-south global array at the equator to establish roughly 20 km x 20 km cells. Only the portion of the grid from 60° N to 60° S (2000 X 664) is saved for the final output.

Temporal Coverage

Intermittent data are available within the following date ranges:

  • Nimbus 1: 29 August to 21 September, 1964
  • Nimbus 2: 16 May to 14 November, 1966
  • Nimbus 3: 17 April, 1969 to 30 November, 1969

Temporal Resolution

Daily

Parameter or Variable

The parameter of interest in this data set is brightness temperature. See the Data Acquisition and Processing section of this document for details.

3. Data Access and Tools

Data Access

Please visit the Order Data page to see options for obtaining NmHRIR3H data files.

Software and Tools

Any GeoTIFF-compatible software package can be used to read and display NmHRIR3G data files.

4. Data Acquisition and Processing

Data Acquisition Methods

The HRIR on the Nimbus I, II, and III satellites transformed measured radiation into electrical voltages that were recorded on tape and played back when the satellite came within range of a receiving station. These data were then transmitted to the Goddard Space Flight Center (GSFC), where they were calibrated, converted to temperatures, and archived on 7-track, digital magnetic tapes. In 2009, the contents of these tapes were recovered and written to a binary tape emulation file format (TAP) for preservation. GES DISC, the NASA Goddard Earth Sciences Data and Information Services Center, archives and distributes these data and maintains historical Nimbus documentation such as instrument user guides and mission reports.

Derivation Techniques and Algorithms

Processing Steps

To construct the daily composites, all reprocessed HRIR swaths for each 24-hour period were accumulated from the Nimbus High Resolution Infrared Radiometer Digital Swath Data Level 1 (NmHRIR1H) data set. When multiple observations were available in a grid cell, the observation closest to satellite nadir was selected. The cosine of the selected observation's view angle is stored in the view angle for brightness temperature data field for users who wish to make additional corrections based on view angle.

The underlying NmHRIR1H data have been corrected to minimize seemingly random alignment errors that caused cloud edges and land features to appear jagged. See Processing Steps in the NmHRIR1H documentation for details.

Quality Assessment

The correction applied in the NmHRIR1H data set improves the visual appearance of the data and better represents the shapes of clouds and coastlines. In regions with very little spatial information, for example where the measurements are very noisy or very uniform, the shifts offer little or no improvement.

Error Sources

Most extant Nimbus 1 and 2 observations were collected at night, however a few daytime orbits have survived. Although the daytime measurements are contaminated by reflected solar radiation, these data have been included for their qualitative and historical value.

Whereas Nimbus I and II operated almost exclusively in nighttime mode, Nimbus III was equipped with an infrared filter that could be inserted into the optical path to acquire daytime reflected solar radiation. However, no flag was set in the data to indicate whether the filter was in or out. Furthermore, a few daytime orbits were collected with no filter in place and contain mixed IR and visible radiation.

In general, daytime orbits appear to correspond to temperatures below 150 K. Bit 7 in the Flags data field is set to on to indicate the PIs' best guess that the filter was in place. Although no calibration exists for the daytime visible data, obvious distinctions between land, cloud, water, and ice surfaces are apparent. However, the visible observations are so scattered in time and space that constructing land surface or cloud maps from these data alone would result in significant sampling errors.

Sensor or Instrument Description

The HRIR on Nimbus I and II was a single scanning radiometer that operated in the 3.4 µm to 4.2 µm near-infrared region. The instrument utilized an optical system and a lead selenide photoconductive detector cell to obtain measurements of blackbody temperatures from 210K – 330K. To allow daytime operation, the Nimbus III HRIR was augmented with a band-pass filter that transmitted reflected solar radiation in the 0.7 µm to 1.3 µm region. The change-over from nighttime to daytime operation was accomplished by actuating a relay, either automatically or by ground station command, to insert the filter into the optical path.

For all three missions, the scan mirror was inclined to 45 degrees with a scan rate of 44.7 revolutions per minute. The instantaneous field of view was 8.8 milliradians and the scan line separation was 8.3 km. The radiometer's instantaneous field of view covered roughly 0.5 degrees, which at an altitude of 1100 km corresponded to a ground resolution of approximately 8 km at nadir.

5. References and Related Publications

References

Gallaher, D., G. G. Campbell, and W. N. Meier. In Press. Anomalous Variability in Antarctic Sea Ice Extents During the 1960's with the Use of Nimbus Satellite Data. Journal of Selected Topics in Applied Earth Observations and Remote Sensing.

Meier, W. N., D. Gallaher, and G. G. Campbell. 2013. New Estimates of Arctic and Antarctic Sea Ice Extent During September 1964 from Recovered Nimbus I Satellite Imagery. The Cryosphere Discuss 7:35-53. doi: 10.5194/tcd-7-35-2013.

Related Web Sites

6. Document Information

Acronyms and Abbreviations

The acronyms used in this document are listed in the following table.

Table 4. Acronyms and Abbreviations
Acronym Description
DAAC Distributed Active Archive Center
ESDT Earth Science Data Type
GeoTIFF Georeferenced Tagged Image File Format
GES DISC Goddard Earth Sciences Data and Information Services Center
GSFC Goddard Space Flight Center
HDF Hierarchical Data Format
HRIR High Resolution Infrared Radiometer
NOAA The National Oceanic and Atmospheric Administration
NSIDC The National Snow and Ice Data Center
NSSDC National Space Science Data Center
TAP Tape Emulation File Format

Document Creation Date

October 2013

Document URL

http://nsidc.org/data/docs/daac/nimbus/nmhrir3g/index.html