Nimbus-5 NEMS Sea Ice Concentration and Brightness Temperatures from 1972-1973

150 days of satellite-derived sea ice data from the Nimbus-5 NEMS radiometer, spanning discrete periods between December 1972 and October 1973. The dataset includes filtered and raw sea ice concentration estimates, brightness temperatures, and associated uncertainty fields, processed with atmospheric correction using collocated ERA5 variables. It was created by Ida Grum-Schwensen Andersen and published in 2026 to extend the microwave satellite climate data record into the early 1970s.

Use Cases

• Analyze historical sea ice extent trends using the filtered sea ice concentration field and its associated timestamps.
• Assess retrieval uncertainty for climate models by comparing the total, smearing, and algorithm standard error fields against the primary concentration estimates.
• Evaluate atmospheric correction methods by comparing uncorrected and atmospherically corrected brightness temperature columns (22.235 GHz and 31.4 GHz).
• Study sensor performance and spatial averaging effects using the smearing uncertainty field linked to the instrument's 180 km footprint.
• Validate reprocessing algorithms by cross-referencing the status flag and quality information with the derived sea ice concentration values.

Strengths

• Provides 150 days of global observational data from a historically sparse period (1972-1973) for climate record extension.
• Includes multiple uncertainty quantifications: total, smearing, and algorithm standard errors for robust error analysis.
• Data is atmospherically corrected using collocated ERA5 variables (total column water vapour, cloud liquid water, wind speed).
• Offers data in both geographic (latitude/longitude) and projected (Lambert Azimuthal Equal-Area) coordinate systems.

Limitations

• Temporal coverage is discontinuous, with data only available for five specific periods totaling 150 days in 1972-1973.
• Spatial resolution is coarse due to the sensor's approximately 180 km diameter footprint, limiting fine-scale analysis.
• Only two of the five original NEMS channels (22.235 GHz and 31.4 GHz) are used and provided in the dataset.

Provenance

Source

Nimbus-5 Nimbus-E Microwave Spectrometer (NEMS) satellite instrument.

Collection Method

Microwave brightness temperatures processed with atmospheric correction using collocated ERA5 data to derive sea ice concentration, following the methodology of Kolbe et al. (2025).

Time Range

Discrete periods between 17 December 1972 and 31 October 1973.

Freshness

Last updated on 2026-03-26, representing a recent reprocessing of historical data.

Geography

Global coverage, with observations defined as sufficient if exceeding 100 per hemisphere per day.