Variations of marine heatwaves and cold spells in northwest Atlantic during 1993–2023
Bibliographic record
Abstract
Abstract. Characteristics of marine heatwaves (MHWs) and cold spells (MCSs) in the northwest Atlantic during 1993–2023 are derived from a global ocean reanalysis product of the EU Copernicus Marine Service. For the surface parameters, the quantification using the reanalysis data is advantageous in regions with the presence of seasonal sea-ice and strong eddies. At the sea bottom, the reanalysis data well reproduces the observed rising trend and sharp increase of bottom temperature around 2012 on Scotian Shelf and associated changes of MHW/MCS parameters. The 31 years of reanalysis data enables the quantification of spatial variations, interannual variations and long-term trends of MHW/MCS parameters in the water column for the first time in our study region. The corresponding parameters of surface MHWs and MCSs are overall similar due to the nearly symmetrical probability distribution of sea surface temperature (SST) anomalies around the mean. On the Scotian Shelf the MHW parameters and temperature present layered structures in the water column. In the upper layer from surface to a mid-depth interface, the nearly uniform MHW mean intensity of ~ 2 ºC can be mainly attributed to variations of the surface heat flux. From the mid-depth interface to about 130 m depth, the MHW mean intensity has high values of 3–3.5 ºC due to the combined effects of downward penetration of upper layer and the lateral advection of water masses. In the deep Emerald Basin below 130 m depth, the MHW intensity has the lowest values of 1.5–2 ºC. The MHW frequency has relatively unform values of 1.5–2 per year in the water column, except low values of less than 1 per year below 130 m depth in the Emerald Basin and below 30 m depth over the Emerald Bank. During 1993–2023, the surface MHW (MCS) total days show increasing (decreasing) trends corresponding to the gradual increasing SST, and the MHW total days reached a peak value of 215 days in 2012 corresponding to the highest annual SST. The bottom temperature shows a stronger increasing trend than the SST, and a sharp increase (regime shift) around 2012, resulting in the increasing (decreasing) trend and regime shift of bottom MHW (MCS) total days. In 2012, the bottom MHW total days experienced a sharp increase and the entire water column was warmer than the climatology. The opposite condition presented in 1998 with the longest bottom MCS total days of ~ 300 near the coast. The quantification of the extreme conditions in 2012 and 1998 supports the results of previous studies on the impacts of these conditions on several marine life species.
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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 | 0.000 | 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".