Assessment of ICESat-2 For the Recovery of the Marine Gravity Anomalies

Abstract:

The Ice, Cloud, and land Elevation Satellite 2 (ICESat-2) laser altimetry mission, launched in September 2018, uses 6 parallel lidar tracks with very fine along-track resolution (15 m) to measure the topography of ice, land, and ocean surfaces. Here we assess the ability of ICESat-2 ocean data for recovery of oceanographic signals ranging from ocean swell (wavelengths from 30 m to 1000 m) to the marine gravity field (wavelengths > 16 km). We focus on a region in the tropical Pacific and study photon height data in both the wavenumber and space domain. Results show that ICESat-2 can recover the marine gravity field at wavelengths > 16 km which is similar to the best radar altimeter data. Moreover, the amplitude, wavelength, and propagation direction of ocean swell is sometimes well resolved by using a combination of the strong and weak beams, which are separated by 90 m. We find higher than expected power in the 1 km to 20 km wavelength band that is caused by either infra-gravity and internal waves, or instrument noise, or is due to aliasing of the large amplitude swell into this longer wavelength band.