Assessment of ICESat-2 for the Recovery of Ocean Topography

Yao Yu (UCSD, United States)

CoAuthors

David Sandwell (UCSD, USA); Sarah Gille (UCSD, USA); Ana Beatriz Villas Bôas (UCSD, USA)

Event: 2020 Ocean Surface Topography Science Team Meeting (virtual)

Session: The Geoid, Mean Sea Surfaces and Mean Dynamic Topography

Presentation type: Type Forum

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 to recover oceanographic signals ranging from surface gravity waves (wavelengths from 30 m to 1000 m) to the marine geoid (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 geoid at wavelengths > 16 km which is similar to the best radar altimeter data. At some times, the amplitude, wavelength, and propagation direction of surface gravity waves is 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 3 km to 20 km wavelength band where geoid and ocean signals should be small. This artificial power is caused by the projection of large amplitude, 2-D surface waves from ~300 m wavelengths into longer wavelengths (5-10 km) because of the 1-D sampling along the narrow ICESat-2 profile. Thus ICESat-2 will not provide major improvements to the geoid in the open ocean, although it may be valuable in small bodies of water where ocean swell has low amplitude.
 
Yao Yu
UCSD
United States
yayu@ucsd.edu