The AMSR-E/NASA Team 2 (NT2) data set of Arctic and Antarctic sea ice concentration is available at daily timesteps and 12.5 km (optionally 25km) spatial resolution for 2002-2011. NT2, an extension of the original NASA Team algorithm, uses AMSR-E 89GHz channels to help resolve ambiguity between low ice concentrations and areas with strong surface effects (due to snow layering and glazing). 89GHz 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. Unlike ASI, NT2 uses the lower frequency channels as well as the high frequency channels. 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. The NSIDC data set also includes estimates of snow depth on sea ice and of bootstrap sea ice retrievals.
Key Strengths:
- Addresses weaknesses of the original NASA Team algorithm, especially with regards to sensitivity to emissivity variations. This leads to significant improvement in the Antarctic.
- Twice the spatial resolution of most other passive microwave sea ice data sets; useful for comparing with high-resolution models
- Provides independent verification of sea ice climatologies and trends in the recent decade compared to SSM/I and SSMI/S data
Key Limitations:
- Not currently being updated; AMSR-E failed in Oct, 2011
- Potential sensitivity of NT2 to weather effects as it uses the 89GHz channel
Years of Record
Formats
Timestep
Data Time Period Extended?
Spatial Resolution
Ocean or Land
Missing Data Flag
Vertical Levels
Input Data
Suggested Data Citation
NSIDC: "Cavalieri, Donald, Thorsten Markus, and Josefino Comiso. 2004, updated daily. AMSR-E/Aqua Daily L3 12.5 km Brightness Temperature, Sea Ice Conentration, & Snow Depth Polar Grids V002, [list the dates of the data used]. Boulder, Colorado USA: National Snow and Ice Data Center. Digital media."
Data Access: Please Cite data sources, following the data providers' instructions.
- Comiso, J. C., D. J. Cavalieri, and T. Markus (2003), Sea ice concentration, ice temperature, and snow depth using AMSR-E data, IEEE Trans. Geosci. Remote Sens., 41(2), 243–252
- Comiso, J. C., and C. L. Parkinson (2008), Arctic sea ice parameters from AMSR-E data using two techniques and comparisons with sea ice from SSM/I, J. Geophys. Res., 113, C02S05, doi:10.1029/2007JC004255
- Parkinson, C. L., and J. C. Comiso (2008), Antarctic sea ice parameters from AMSR-E data using two techniques and comparisons with sea ice from SSM/I, J. Geophys. Res., 113, C02S06, doi:10.1029/2007JC004253
- Markus, T. and D.J. Cavalieri, An enhancement of the NASA Team sea ice algorithm, IEEE Trans. Geoscience Remote Sensing, 38, 1387-1398, 2000.
- Markus, T., Cavalieri, D., and A. Ivanoff. 2011. Algorithm Theoretical Basis Document for the AMSR-E Sea Ice Algorithm, Revised December 2011. Landover, Maryland USA: Goddard Space Flight Center. (pdf)
- Meier, W. (2005), Comparison of passive microwave ice concentration algorithm retrievals with AVHRR imagery in arctic peripheral seas, IEE Transactions on Geosciences and Remote Sensing, 43(6), 1324-1337.
- Andersen, S., R. Tonboe, L. Kaleschke, G. Heygster, and L. T. Pedersen (2007), Intercomparison of passive microwave sea ice concentration retrievals over the high-concentration Arctic sea ice, J. Geophys. Res., 112, C08004, doi:10.1029/2006JC003543.
- Spreen, G., L. Kaleschke, and G.Heygster(2008), Sea ice remote sensing using AMSR-E 89 GHz channels J. Geophys. Res.,vol. 113, C02S03, doi:10.1029/2005JC003384.