Project Description

Nimbus-7 Scanning Multichannel Microwave Imager (SMMR)
Polar Gridded Radiances and Sea Ice Concentrations

---

Summary

The SMMR mission was to obtain nearly all-weather observations of sea surface temperatures, near-surface ocean winds, water vapor over oceans, sea ice concentration, sea ice age, sea ice radiating temperature and land snow cover. Earlier, single-frequency, passive microwave imagers (ESMR) were limited in their capacities to distinguish between ice types or accommodate variations in ice temperatures. The advanced SMMR made it possible to differentiate ice types from space for the first time, and, having the distinction of being on the air longer than any other satellite-borne microwave instrument (Gloersen et al. 1992), has provided a baseline for tracking global change.

Table of Contents

1. Project Overview
2. Data Availability
3. Access
4. Principal Investigator
5. Submitting Investigator
6. References
7. Detailed Description

1.Project Overview

Work on the Scanning Multichannel Microwave Imager (SMMR) might be thought of as growing out of frustration and success. Researchers were initially frustrated in their attempts to obtain the views they needed for exacting polar studies:

"By the late 1960's, it was apparent that the sequential synoptic observations needed for sea ice and climate studies could not be acquired by satellite-borne visible sensors, which are limited to cloud-free and well-illuminated conditions, not frequently met in the polar regions...." (Gloersen 1992)

Persevering work however, led to encouraging success with ESMR, which

"proved convincingly that it was indeed possible to monitor remotely sea ice distribution in the dark of the polar night and through clouds." (ibid.)

and provided the necessary motivation to further stretch technical boundaries.

The SMMR was evolved to obtain sea surface temperature and near-surface winds. From the data delivered by the instrument, those and many other parameters were derived, including: (in polar regions) sea ice concentration, multiyear ice fraction, radiating temperatures, extent and water equivalence of snow cover over terrain, and (over open oceans)atmospheric water vapor in a column and rainfall rates.

In archiving the Nimbus-7 SMMR Polar Radiances and Arctic and Antarctic Sea Ice Concentrations , NSIDC seeks to provide the complete SMMR sensor time series brightness temperature and derived sea ice concentration data, gridded to the SSM/I polar stereographic grids for the North and South Polar regions, for the interest and use of the polar science community.

Scientists availing of the SMMR data can be defined in the broadest terms, and include practitioners in all the oceanographic and climatological disciplines, especially as they relate to the Polar Regions.

Please refer to the Scanning Multichannel Microwave Radiometer data set documentation.

2. Data Availability

Data Types

The SMMR brightness temperatures and sea ice concentrations on these 12 CD-ROM volumes are gridded in the polar stereographic projection with grid elements of 25 X 25 km. The CD-ROMs are mastered to the ISO 9660 industry standard. Note that SMMR files have neither PDS labels nor HDF headers. The SMMR brightness temperature files contain 2-byte (16 bit) integers; sea ice concentration files contain 1-byte (8 bit) integers.

Input/Output Media

The Nimbus-7 SMMR Polar Radiances and Arctic and Antarctic Sea Ice Concentrations are available from NSIDC on 12 CD-ROMs.

3. Access

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

4. Principal Investigator

This CD-ROM series, Nimbus-7 SMMR Polar Radiances and Arctic and Antarctic Sea Ice Concentrations was produced by P. Gloersen of the Oceans and Ice Branch, NASA Goddard Space Flight Center, with the support of the National Aeronautics and Space Administration, Headquarters, Climate and Hydrologic System Division, Cryosphere Branch.

The assistance of Dr. Gloersen in incorporating information from his SMMR Atlas (Gloersen et al. 1992) is gratefully acknowledged.

5. Submitting Investigator

See section 4 of this document.

6. References

Please see the bibliography for a complete list of references.

7. Detailed Description

For complete information, please refer to the data set documentation for the Nimbus-7 SMMR Polar Radiances and Arctic and Antarctic Sea Ice Concentrations on CD-ROM.

---

Document Type: Project Document
Revision Date: December 1995