Abstract
Abstract. This article describes the observation techniques and suggests processing methods to estimate dynamical sea-ice parameters from data of the Earth Explorer 10 candidate Harmony. The two Harmony satellites will fly in a reconfigurable formation with Sentinel-1D. Both will be equipped with a multi-angle thermal infrared sensor and a passive radar receiver, which receives the reflected Sentinel-1D signals using two antennas. During the lifetime of the mission, two different formations will be flown. In the stereo formation, the Harmony satellites will fly approximately 300 km in front and behind Sentinel-1, which allows for the estimation of instantaneous sea-ice drift vectors. We demonstrate that the addition of instantaneous sea-ice drift estimates on top of the daily integrated values from feature tracking have benefits in terms of interpretation, sampling and resolution. The wide-swath instantaneous drift observations of Harmony also help to put high-temporal-resolution instantaneous buoy observations into a spatial context. Additionally, it allows for the extraction of deformation parameters, such as shear and divergence. As a result, Harmony's data will help to improve sea-ice statistics and parametrizations to constrain sea-ice models. In the cross-track interferometry (XTI) mode, Harmony's satellites will fly in close formation with an XTI baseline to be able to estimate surface elevations. This will allow for improved estimates of sea-ice volume and also enables the retrieval of full, two-dimensional swell-wave spectra in sea-ice-covered regions without any gaps. In stereo formation, the line-of-sight diversity allows the inference of swell properties in both directions using traditional velocity bunching approaches. In XTI mode, Harmony's phase differences are only sensitive to the ground-range direction swell. To fully recover two-dimensional swell-wave spectra, a synergy between XTI height spectra and intensity spectra is required. If selected, the Harmony mission will be launched in 2028.
Highlights
Sea ice plays a vital role in the climate system, reflecting sunlight and acting as an insulator between the ocean and the atmosphere
We demonstrate how wave spectra can be retrieved based on an end-to-end simulator and argue that Harmony is able to retrieve two-dimensional wave spectra in both formations
We presented the observation principle, several processing methods and the simulated performance of Harmony for sea ice
Summary
Sea ice plays a vital role in the climate system, reflecting sunlight and acting as an insulator between the ocean and the atmosphere. While satellites have monitored large-scale sea-ice extent for more than 40 years, sea-ice thickness on a large scale was only sampled sporadically in the 2000s from ICESat (Lindsay and Schweiger, 2015) and is currently monitored using both CryoSat-2 (Ricker et al, 2017) and ICESat-2 (Kwok et al, 2019; Petty et al, 2020) These data have suggested an overall decline in Arctic sea-ice thickness and total ice volume (Ricker et al, 2014; Armitage and Ridout, 2015), while thickness trends in the Antarctic remain uncertain (Price et al, 2019)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
