Influence of Atlantic inflow on the freshwater content in the upper layer of the Arctic basin
Bibliographic record
Abstract
Inter-decadal changes in the water layer of Atlantic origin and freshwater content (FWC) in the upper 100 m layer were traced jointly to assess the influence of inflows from the Atlantic on FWC changes based on oceanographic observations in the Arctic Basin for the 1960s – 2010s. For this assessment, we used oceanographic data collected at the Arctic and Antarctic Research Institute (AARI) and the International Arctic Research Center (IARC). The AARI data for the decades of 1960s – 1990s were obtained mainly at the North Pole drifting ice camps, in high-latitude aerial surveys in the 1970s, as well as in ship-based expeditions in the 1990s. The IARC database contains oceanographic measurements acquired using modern CTD (Conductivity – Temperature – Depth) systems starting from the 2000s. For the reconstruction of decadal fields of the depths of the upper and lower 0 °С isotherms and FWC in the 0–100 m layer in the periods with a relatively small number of observations (1970s – 1990s), we used a climatic regression method based on the conservativeness of the large-scale structure of water masses in the Arctic Basin. Decadal fields with higher data coverage were built using the DIVAnd algorithm. Both methods showed almost identical results when compared. The results demonstrated that the upper boundary of the Atlantic water (AW) layer, identified with the depth of zero isotherm, raised everywhere by several tens of meters in 1990s – 2010s, when compared to its position before the start of warming in the 1970s. The lower boundary of the AW layer, also determined by the depth of zero isotherm, became deeper. Such displacements of the layer boundaries indicate an increase in the volume of water in the Arctic Basin coming not only through the Fram Strait, but also through the Barents Sea. As a result, the balance of water masses was disturbed and its restoration had to occur due to the reduction of the volume of the upper most dynamic freshened layer. Accordingly, the content of fresh water in this layer should decrease. Our results confirmed that FWC in the 0–100 m layer has decreased to 2 m in the Eurasian part of the Arctic Basin to the west of 180° E in the 1990s. In contrast, the FWC to the east of 180° E and closer to the shores of Alaska and the Canadian archipelago has increased. These opposite tendencies have been intensified in the 2000s and the 2010s. A spatial correlation between distributions of the FWC and the positions of the upper AW boundary over different decades confirms a close relationship between both distributions. The influence of fresh water inflow is manifested as an increase in water storage in the Canadian Basin and the Beaufort Gyre in the 1990s – 2010s. The response of water temperature changes from the tropical Atlantic to the Arctic Basin was traced, suggesting not only the influence of SST at low latitudes on changes in FWC, but indicating the distant tropical impact on Arctic processes.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 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) | 0.000 | 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 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".