Assessment of <i>L</i> -Band Passive Microwave Soil Moisture Retrievals Against In Situ Measurements in the North American Boreal Biome
Bibliographic record
Abstract
Climate change greatly impacts forest carbon and water dynamics in the boreal biome. To understand the vulnerability of the North American boreal biome to climate change disturbances, including droughts and temperature extremes, a biome-wide characterization of near-surface soil moisture (SM) is essential. SM is an important control on photosynthetic carbon dioxide uptake and the associated evaporative loss of water through transpiration. Two missions with passive microwave radiometers operating at <italic>L</italic>-band (1–2 GHz) were launched to estimate SM at a global scale: soil moisture and ocean salinity (SMOS) launched in 2009 and soil moisture active passive (SMAP) launched in 2015. In this study, we analyzed the relationships between various microwave observations [brightness temperature (TB), soil reflectivity (<italic>r</italic>), and soil moisture (SM)] derived from SMOS and SMAP with in situ SM measurements (2016–2021) over 16 sites across the boreal biome of North America. Our results show good agreement between SMAP and SMOS in terms of relationships between TB and in situ SM measurements (with a coefficient of determination <italic>R</italic> <sup>2</sup> > 0.7). Analysis comparing microwave variables (TB, <italic>r,</italic> and SM) and in situ SM data demonstrated considerable differences across sites and years. We observed moderate to strong correlation coefficients (R_TB > 0.5) between the TB and in situ SM data, generally when a seasonal soil drying trend emerges over the summer. However, soils with high water content and frequent precipitation input showed weaker correlations between TB and in situ SM. By analyzing the correlations between <italic>r</italic> and in situ SM data, we demonstrated that the soil effective temperature partly affects performances in terms of R_TB. Comparisons with other SMAP SM retrievals (multitemporal dual-channel algorithm and multichannel collaborative algorithm) revealed similar results in correlations and showed high spatiotemporal differences across all SM retrievals and study sites. Our findings highlight the complexity of the interactions between microwave observations and SM dynamics across the boreal biome, thus challenging the <italic>L</italic>-band passive microwave SM retrievals.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".