Back to research

Research

Deep Learning for Radar Altimetry Echo Generation in Sea Ice Surface Image Recognition

Zijin Su†, Michel Tsamados*, Weibin Chen, Ryan Nichol, Connor Nelson, Stefan Hendricks, and Jack C. Landy. Preparing for submission, 2026. †First author; *corresponding author.

Abstract

Sea-ice radar echoes are difficult to interpret because snow, roughness, open-water leads, and mixed surface types can all change the returned waveform within one satellite footprint. This project treats waveform formation as a cross-modal generation problem: from co-located Sentinel-3 OLCI optical image patches, a conditional generative model learns to produce the corresponding SRAL radar-altimetry waveforms. I evaluate the generated echoes by waveform accuracy, morphological descriptors, and retracking-based physical consistency, showing how multimodal deep learning can link visible sea-ice structure with radar-altimetry response for waveform interpretation and sea-ice retrieval. A key design is to encode the waveform in physically meaningful segments rather than as a single undifferentiated curve. This helps the model focus on the leading edge, trailing edge, peak structure, and retracker-relevant regions that carry most of the geophysical information.

Sea Ice SAR Altimetry Sentinel-3 OLCI/SRAL Waveform Generation cGAN Diffusion

Representative Results

Image-to-waveform generation

Representative comparison of sea-ice image patches and generated SAR altimetry waveforms across baseline and proposed models.

Comparison of sea-ice image patches and radar altimetry waveform generation models

Model Architecture

Region-aware waveform generation

A conditional generator maps co-located optical image patches into SAR altimetry waveforms, while region-aware discriminators provide targeted supervision over the physically informative echo segments.

RWcGAN model architecture for radar altimetry waveform generation

Waveform Metrics

Waveform morphology consistency

Generated and observed echoes are compared through retracker-relevant waveform descriptors across sea-ice and lead samples.

Comparison of real and simulated leading-edge width for sea-ice and lead waveforms
Leading-edge width
Comparison of real and simulated trailing-edge width for sea-ice and lead waveforms
Trailing-edge width
Comparison of real and simulated pulse peakiness for sea-ice and lead waveforms
Pulse peakiness
Comparison of real and simulated retrack positions for sea-ice and lead waveforms
Retrack position

Geophysical Retrieval

Retracked geophysical consistency

Generated waveforms are evaluated through downstream retracking to test whether their derived surface properties remain physically consistent.

Comparison of real and simulated sea surface height anomaly for sea-ice and lead waveforms
Sea surface height anomaly
Comparison of real and simulated macro-topography for sea-ice and lead waveforms
Macro-topography
Comparison of real and simulated surface roughness for sea-ice and lead waveforms
Roughness
Comparison of real and simulated waveform peak amplitude for sea-ice and lead waveforms
Peak amplitude

Demo

Along-track reconstruction

A compact animation demonstrates how generated waveform products vary along the Sentinel-3 track.