Implications of Both Statistical Equilibrium and Global Warming Simulations with CCSM3. Part I: On the Decadal Variability in the North Pacific Basin
Bibliographic record
Abstract
Abstract In the low-resolution version of the Community Climate System Model, version 3 (CCSM3), the modeled North Pacific decadal variability is demonstrated to be independent of the epoch for which a statistically steady control simulation is constructed, either preindustrial or modern; however, it is demonstrated to be significantly affected by the different global warming scenarios investigated. In the control simulations, the North Pacific basin is shown to be dominated by sea surface temperature (SST) variability with a time scale of approximately 20 yr. This mode of variability is in close accord with the observed characteristics of the Pacific decadal oscillation (PDO). A detailed analysis of the statistical equilibrium runs is performed based on other model variables as well [sea surface salinity (SSS), barotropic circulation, freshwater and heat fluxes, wind stress curl, sea ice, and snow coverage]. These analyses confirm that the underlying mechanism of the PDO involves a basin-scale mode of ocean adjustment to changes of the atmospheric forcing associated with the Aleutian low pressure system. However, they also suggest that the observed sign reversal of the PDO arises from a feedback in the northern part of the basin. In this novel hypothesis, the advection to the Bering Sea of “spice” anomalies formed in the central and western Pacific sets up a typical 10-yr time scale for the triggering of the PDO reversal. In all of the global warming simulations described in this paper, the signal represented by the detrended SST variability in the North Pacific displays significant power at multidecadal frequencies. In these simulations, the natural North Pacific decadal variability, as characterized in the control simulations (the PDO), remains the leading mode of variability only for moderate forcing. If the warming is too strong, then the typical 20-yr time scale of the canonical PDO can no longer be detected, except in terms of SSS variability and only prior to a significant change that occurs in the Bering Strait Throughflow.
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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 | 0.002 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".