ICESat-2 Level-3B Products

Image courtesy NASA/Kathryn Hansen.

Annual Land Ice Height (ATL11)

ATL11 provides time series of surface heights. It is the lowest-level land-ice product that brings together data from multiple passes over the same points, obviating the need to collect individual ATL06 files for this task. ATL11 contains height estimates both for crossovers and for along-track reference points between crossovers. The product uses consistency checks to cull blunders from the ATL06 record, computes a local-topography correction to remove height variations due to small-scale surface slopes, and contains values that can be directly differenced to obtain height changes through time (dh/dt).

Gridded Weekly (ATL16), Monthly (ATL17) Atmosphere

These two products, which differ only in grid resolution and frequency at which they are produced, will report global cloud fraction, total column optical depth over the oceans, polar cloud fraction, blowing snow frequency, apparent surface reflectivity, and ground detection frequency. The HDF product files will contain gridded 2D arrays plus images of the data fields plotted on a map of the region.

Gridded Monthly Sea Surface Height:
Open Ocean (ATL19)

Derived entirely from ATL12 (Ocean Surface Height), ATL19 will contain gridded monthly estimates of sea surface height using all ICESat-2 tracks from the beginning to the end of each month. It will include statistical descriptions of the sea surface—mean, standard deviation, skewness, and kurtosis—within each grid cell.

Gridded Annual Ice Sheet Height (ATL14),
Ice Sheet Height Change (ATL15)

The ATL14 product will use slope-corrected heights from ATL11 to generate Digital Eleveation Models (DEMs) for Antarctica and Greenland posted at 125 meters. ATL15 will synthesize height measurements from ATL06 (Land Ice Height) and the first ICESat mission, to produce maps of height change for different time windows: one between the midpoint of the ICESat mission and the start of ICESat-2; and one for each year of the ICESat-2 mission.

ICESat–ICESat-2 elevation difference maps will be posted at 1 km. ATL14 elevation change surfaces will be posted at 500 m per 3 months.

Gridded Land and Vegetation Height (ATL18)

The data set consists of gridded maps for terrain and canopy features. The product will be released annually at a coarse resolution, for example, 500 m to 1 km tiles (to be determined). ATL18 will include canopy height, canopy cover, and ground elevation. Higher resolution grids are planned at the end of the mission.

Gridded Monthly Sea Ice Freeboard (ATL20),
Sea Surface Height: Ice-Covered Ocean (ATL21)

ATL20 and ATL21 consist of gridded estimates of sea ice freeboard and sea surface height (ice-covered ocean) for both Arctic and Southern Oceans. ATL20 reports sea ice freeboard from all ICESat-2 tracks between the beginning and the end of each month. ATL21 is still in development and will provide monthly averages of sea surface height from all ICESat-2 tracks between the beginning and the end of each month. Both data sets are gridded at 25 km  and mapped onto a planimetric grid using the SSM/I Polar Stereographic Projection equations.