ICESat-2 Level-3A Products

Image courtesy NASA.

Land Ice Height (ATL06)

ATL06 provides geolocated estimates of land-ice surface heights and ancillary parameters that can be used to interpret the estimates and assess their quality. Photon events are aggregated into overlapping, along-track segments of a fixed length (40 m) whose centers are 20 meters apart, and the algorithm estimates the along-track slope and height at the center of each segment. Across-track slopes are calculated when both beams in a pair obtain height measurements.

Land and Vegetation Height (ATL08)

ATL08 estimates terrain height, canopy height, and canopy cover at 100 meter, fixed-length steps along the ground track. The surface finding algorithm computes an interpolated ground surface and determines the relative canopy height by differencing the height of canopy photons returns from the height of the interpolated ground surface.

Sea Ice Freeboard (ATL10)

This data set provides estimates of along-track, total freeboard for the ice-covered seas of the northern and southern hemispheres along segments generated in the ATL07 product. Freeboard is determined using a reference sea surface height established from within-segment leads (open ocean). Two files are provided per day, one each for the north and south, which contain the sixteen intra-day orbits broken out by hemisphere.

Inland Water Surface Height (ATL13)

ATL13 consists of along-track water surface height, slope, and roughness for each ATLAS beam, plus aspect and maximum slope (or gradient) of the planar surface between adjacent strong beams. In addition, the product includes: water surface height statistics; mean quantities such as sub-surface backscatter attenuation coefficient and significant wave height, when applicable; and along track water-body surface maximum slope and aspect with respect to North, derived from adjacent ATLAS strong beams.

Sea Ice Height (ATL07)

ATL07 provides along-track surface height and type (e.g., snow-covered ice, open water) for the ice-covered seas of the northern and southern hemispheres. Sea surface and sea ice height are estimated for segments along each of the six ground tracks. Segment length varies with surface type, determined by the distance over which ~100 signal photons are accumulated. Two files are provided per day, one each for the north and south, which contain the sixteen intra-day orbits broken out by hemisphere.

Atmospheric Layer Characteristics (ATL09)

ATL09 reports layer heights and related flags detected from atmospheric backscatter profiles (ATL04). This product also includes two cloud flags, a blowing snow flag, and a multiple scattering warning flag. Heights are available for a maximum of ten layers for each of the three strong beams and a layer attribute flag differentiates clouds from aerosols.

Ocean Surface Height (ATL12)

ATL12 will contain estimates of the sea surface height at a given point on the open ocean surface at a given time, plus parameters needed to assess the quality of the height estimates and interpret and aggregate the data over greater distances. The ice-free, ocean surface height, including coastal waters, is provided at length scales between 70 m (100 Hz) and 7 km (1 Hz) for each of three ATLAS strong beams. ATL12 also includes height distribution estimates (decile bins), significant wave height, surface slope, and apparent reflectance.