Sea ice concentration data from NASA Goddard based on SSMI and NASA Team (NT2) algorithm
The NASA Team 2 (NT2) / SSMI data set of Arctic and Antarctic sea ice concentration is available at daily timesteps and 25km spatial resolution for 1992-2008. NT2, an extension of the original NASA Team algorithm, uses SSMI 85GHz channels to help resolve ambiguity between low ice concentrations and areas with strong surface effects (due to snow layering and glazing). 85GHz channels introduce more weather contamination. NT2 implements a radiative transfer model to filter for weather that simulates brightness temperatures under several idealized polar atmospheres. The algorithm searches for the best fit between the observed and modeled brightness temperature ratios to pick the final concentration. Sea ice from NT2 is more similar to Bootstrap sea ice than was the original NASA Team sea ice. Some differences are still apparent; NT2 usually shows slightly higher concentrations in the Antarctic and more sensitivity to thin ice. This data set overlaps with those using the same satellite data but different algorithms, including the Goddard/NSIDC Bootstrap and NASA Team data sets, facilitating useful comparisons that can serve as a measure of uncertainty.
Addresses weaknesses of the original NASA Team algorithm, especially with regards to sensitivity to emissivity variations. This leads to significant improvement in the Antarctic.
Potential sensitivity of NT2 to weather effects as it uses the 85GHz channel
Short period of record
SSMI: multiple channels
25 x 25 km