Monthly and seasonal variations in ocean near-surface gradients around Santo Antão Island: A 20-year MODIS-aqua study
Bibliographic record
Abstract
• Chl a , Kd 490 , and POC co-varied, indicating oligotrophic waters in Santo Antão. • Light is not the primary limiting factor for productivity in this region. • PIC patterns were distinct from all other bio-optical parameters. • Surface gradients shaped by ocean–atmosphere and large to regional scales dynamics. Understanding the baseline environmental conditions of the Santo Antão marine ecosystems is essential for effective conservation. This study characterised the long-term spatial variability of near-surface biophysical properties of the waters surrounding Santo Antão by utilizing 20 years of MODIS-Aqua Level-2 imagery with 1 km spatial resolution for Ocean Colour and Thermal Infrared parameters, supplemented by altimetry data. Sea Surface Temperature (SST) results revealed a persistent thermal gradient, with warmer waters in the NW-W-SW quadrant and cooler waters in the NE-E-SE quadrant, indicating the influence of regional oceanic currents and interactions between subtropical and tropical gyres. Chlorophyll a (Chl a ), Diffuse Attenuation Coefficient (Kd 490 ), and Particulate Organic Carbon (POC) exhibited similar spatial gradients and were highly correlated, reflecting the oligotrophic nature of Case-1 waters. Notably, the correlation between Kd 490 and Chl a was strong (r ≈ 0.92), while POC showed an even higher correlation (r ≈ 0.95), reinforcing their roles as significant indicators of phytoplankton biomass. In contrast, Particulate Inorganic Carbon (PIC) concentrations displayed distinct spatial patterns and demonstrated a weak negative correlation with Chl a (r ≈ −0.27), indicating that PIC operates independently of the bulk phytoplankton community represented by Chl a . This independence emphasises the need to interpret PIC values with caution, as they may not accurately reflect biological productivity in these waters. Photosynthetically Available Radiation (PAR) displayed limited seasonal variation and a weak negative correlation with Chl a , suggesting that light availability is not a primary limiting factor for phytoplankton productivity in the region. The observed spatial patterns and gradients in biophysical parameters are interpreted in the context of various ocean–atmosphere interactions, including the prevailing northeast trade winds, Sea Surface Height (SSH), and surface currents, which are modulated by larger-scale circulation patterns. These mechanisms should influence nutrient availability and ultimately affect productivity distribution around the island. Overall, this study highlights the complex interplay of monthly and seasonal ocean–atmosphere spatial dynamics, along with regional and large-scale oceanographic conditions, in shaping the near-surface gradients around Santo Antão. By integrating these diverse datasets, this study provides new insights into the region’s ocean dynamics, emphasising its significance for conservation efforts in this area.
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 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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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".