Exploring Radarsat-2 SAR Cross-Polarization Ratio Capability for Tundra Snow Depth Estimation Using Numerical and Deep Learning Approach
Bibliographic record
Abstract
Snow is essential to the Earth system, significantly influencing the global climate, freshwater availability, and economic activities. A significant snow cover decline has been reported in vast northern hemisphere areas. The decrease in snow cover will affect more than one-sixth of the world's population who rely on the snow as a freshwater supplement. Snow mass, often expressed as snow water equivalent (SWE), signifies the quantity of water held in the form of snow on the Earth's surface, and it plays a crucial role in the functioning of water, energy, and geochemical processes. Since the seasonal snow has a high spatial variability at regional and local scales, surface observations cannot provide sufficient SWE information. The quality of global SWE estimates needs to be improved. In recent years, C-band spaceborne SAR has shown a high potential for global monitoring of SWE. This thesis aims to explore the current spaceborne C-band SAR signal sensitivity to Arctic tundra snow and define a suitable approach for estimating deep snow depth through the tundra environment. The noticeable variation of C-band backscatter with the snow depth generally demonstrated the C-band sensitivity to dry snow for the deep snow. These areas are dominated by tall vegetation areas such as tall shrubs and riparian shrubs. The cross-polarization ratio method also shows a higher correlation with snow depth than cross-pol and co-pol backscatter, which is generally consistent with earlier research. Also, numerical, and deep learning (DL) approaches were tested based against drone-based snow depth reference data. The result shows that the numerical approach may only be valid in a place with over 2.5 m snowpack. Compared to the numerical approach, the DL approach shows a better evaluation, resulting in a correlation coefficient of R 0.79 between the estimated and target snow depth with a root mean square error (RMSE) of 19 cm. The DL approach can be more suitable for estimating snow depth from C-band SAR observation under the Arctic tundra snow environment.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".