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Laboratory for Satellite Altimetry / Sea Ice and Polar Dynamics Science Team

Surface Elevation

The sea ice surface elevation product is derived from Airborne Topographic Mapper (ATM) lidar elevation data acquired during the late winter months of March, April, and May during NASA's annual Operation IceBridge (OIB) airborne campaigns in the Arctic.

Due to the conical scanning geometry of the ATM lidar (Krabill, 2002), across-track sampling (green dots, Figure 1) is non-uniform, with sampling density greatest at the swath edges. To account for the variation in sample density, ATM elevation data are gridded. Each grid cell (numbered red boxes, Figure 1) has an along-track dimension of 30 m and an across-track dimension that is inversely proportional to the across-track sampling density. For example, at a nominal flight altitude of 500 m, cells at the swath edges are ~ 6 m wide in the across-track direction, while cells at the center of the swath are ~ 34 m wide in the across-track direction. The grid configuration optimizes ATM sample density providing high-resolution measurements of sea ice surface elevation while still containing enough point measurements for robust statistical calculations.

Depiction of gridding

Figure 1. Depiction of grid configuration applied to ATM lidar elevation data in the derivation of the surface elevation product. Grid cells are numbered in the across-track direction using a column reference value of 1-10.


Data Product and Data Access

The NOAA / NESDIS / STAR / Laboratory for Satellite Altimetry (LSA) Polar Ocean Data System (PODS) Arctic Sea Ice Surface Roughness is derived from ATM lidar elevation measurements acquired during annual, low-altitude NASA OIB airborne surveys over Arctic sea ice. ATM measurements were acquired between March and May, 2009–2019. The mean elevation, standard deviation of elevation, and the number of ATM measurements is derived along-track, per grid cell (Figure 1), for each aircraft flight line.

Acknowledgment:Users are free to use the information hosted on this site in their research, provided credit is given to the NOAA / NESDIS Center for Satellite Applications and Research (STAR) Laboratory for Satellite Altimetry (LSA). Users are also asked to cite the following publication whenever these data are used: Connor, L., S. Farrell and D. McAdoo (2017), A decadal study of interannual variability in Arctic sea ice freeboard using airborne laser altimetry (2006-2016), presented at the 2017 IGS International Symposium on Polar Ice, Polar Climate, and Polar Change, Boulder, Colorado, 14-19 Aug. 2017.

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End Users

The surface elevation data product can be used to improve the characterization of sea ice surface roughness, freeboard, and thickness in high-resolution sea ice models. It also provides a basis for calibration and validation for sea ice surface roughness, freeboard, and thickness measurements derived from other satellite missions such as ASCAT, Sentinel-3A/B, CryoSat-2, and ICESat-2. End users of this sea ice data product include modelers and academia conducting basic research.