Changing correlation structures of the Northern Hemisphere atmospheric circulation from 1000 to 2100 AD
Bibliographic record
Abstract
Abstract. Atmospheric circulation modes are important concepts to understand the variability of atmospheric dynamics. Assuming their spatial patterns to be fixed, such modes are often described by simple indices derived from rather short observational data sets. The increasing length of reanalysis products allows scrutinizing these concepts and assumptions. Here we investigate the stability of spatial patterns of Northern Hemisphere teleconnections by using the Twentieth Century Reanalysis as well as several control and transient millennium-scale simulations with coupled models. The observed and simulated centers of action of the two major teleconnection patterns, the North Atlantic Oscillation (NAO) and to some extent the Pacific North American (PNA), are not stable in time. The currently observed dipole pattern of the NAO with its center of action over Iceland and the Azores split into a North-South dipole pattern in the western Atlantic and a wave train pattern in the eastern part connecting the British Isles with West Greenland and the Eastern Mediterranean in the period 1940–1969 AD. The PNA centers of action over Canada are shifted southwards and over Florida into the Gulf of Mexico in the period 1915–1944 AD. The analysis further shows that shifts in the centers of action of either telconnection pattern are not related to changes in the external forcing applied in transient simulations of the last millennium. Such shifts in their centers of action are associated with changes in the relation of local precipitation and temperature to the overlying atmospheric mode. These findings further undermine the assumption of stationarity between local climate/proxy variability and large-scale dynamics inherent in proxy-based reconstructions of atmospheric modes and call for a more robust understanding of atmospheric variability on decadal time scales.
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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 | 0.000 | 0.000 |
| 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) | 0.001 | 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".