Air‐sea CO<sub>2</sub> fluxes and the continental shelf pump of carbon in the Chukchi Sea adjacent to the Arctic Ocean
Bibliographic record
Abstract
The Chukchi Sea, a shallow sea‐ice covered coastal sea adjacent to the Arctic Ocean, exhibits an intense bloom of phytoplankton each year due to the exposure of nutrient‐laden surface waters during the brief summertime retreat and melting of sea‐ice. The impact of phytoplankton production and other factors on the seasonal dynamics of carbon and air‐sea CO2 fluxes were investigated during two survey cruises (5 May–15 June 2002, and 17 July–26 August 2002), as part of the Western Arctic Shelf‐Basins‐Interactions (SBI) project. In springtime, most of the Chukchi Sea was sea‐ice covered (>95%) and remnant winter water was present across the shelf. Surface layer seawater partial pressure of CO2 (pCO2) ranged from ∼200–320 μatm, indicative of undersaturation with respect to atmospheric pCO2, although sea‐ice cover kept rates of air‐to‐sea CO2 flux generally low (<1 mmoles CO2 m2 d−1). By summertime, after sea‐ice retreat, seawater pCO2 contents had decreased to very low values (<80–220 μatm) in response to high rates of localized primary and net community production (NCP) and biological uptake of dissolved inorganic carbon (DIC). In the seasonally sea‐ice free regions of the Chukchi Sea shelf, rates of air‐to‐sea CO2 fluxes, determined using the quadratic wind speed‐transfer velocity relationships of Wanninkhof (1992), were high, ranging from ∼30–90 mmoles CO2 m−2 d−1. In regions of the Chukchi Sea slope (and western Beaufort Sea shelf and Arctic Ocean basin) where sea‐ice cover remained high (>80%), air‐to‐sea CO2 fluxes remained generally low (<2 mmoles CO2 m−2 d−1). Seasonal (i.e., May to September) and annual net air‐to‐sea CO2 fluxes from the Chukchi Sea shelf were estimated at ∼27 ± 7 Tg C yr−1, and 38 ± 7 Tg C yr−1, respectively. The Chukchi Sea represents the largest oceanic CO2 sink in the marginal coastal seas adjacent to the Arctic Ocean. An active continental shelf pump of carbon, driven by the northward transport of nutrient‐rich water of Pacific Ocean origin, high rates of primary and net community production during the sea‐ice free period, and lateral export of organic carbon, maintains the Chukchi Sea shelf and slope as a perennial ocean CO2 sink.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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".