GLAH06: GLAS/ICESat Level-2 Laser Altimetry Corrections

GLAH06 data provide the geodetic, instrument, and atmospheric corrections required to generate four distinct Level-2 surface elevation products for ice sheets, sea ice, land, and oceans. Each regional product is processed with surface-type-specific algorithms, and overlapping masks can cause the same raw data to be written to multiple products for different elevation calculations. These corrections are archived at 14 orbits per granule and are versioned at the National Snow and Ice Data Center (NSIDC) for traceability.

Use Cases

• Calculating precise ice sheet elevation change based on corrected laser range measurements.
• Analyzing sea ice freeboard and thickness using altimetry data filtered by the sea ice surface mask.
• Studying land surface topography with geodetic and atmospheric corrections applied.
• Investigating ocean surface roughness and wave height from corrected ocean altimetry records.
• Comparing elevation algorithms for overlapping surface types (e.g., sea ice vs. ocean) where data is written to multiple products.

Strengths

• Data is processed with algorithms specific to four distinct surface types (ice sheets, sea ice, land, oceans).
• Surface type masks are versioned and archived at NSIDC, providing traceability for data selection.
• Includes multiple correction types: geodetic, instrument, and atmospheric for range measurements.

Limitations

• Critical metadata is missing: no column names, row counts, file sizes, or specific license are provided.
• Conflicting 'last updated' dates exist between sources (2009 vs. 2026), creating uncertainty about data freshness.
• Documentation is sparse; detailed data structure and granularity beyond '14 orbits per granule' are not described.

Provenance

Source

National Aeronautics and Space Administration

Collection Method

Satellite laser altimetry from the GLAS/ICESat instrument.

Time Range

null

Freshness

2026-04-10 19:45:36.728625

Geography

Global, with regional products demarcated at ± 50° latitude.