Spiky Fluctuations and Scaling in High-Resolution EPICA Ice Core Dust Fluxes
Bibliographic record
Abstract
Abstract. Atmospheric variability as a function of scale has been divided in various dynamical "regimes" with alternating increasing and decreasing fluctuations: weather, macroweather, climate, macroclimate, megaclimate. Although a vast amount of data is available at small scales, the larger picture is not well constrained due to the scarcity and low resolution of long paleoclimatic time-series. Using statistical techniques originally developed for the study of turbulence, we analyse the fluctuations of a centimetric resolution dust flux time-series from the EPICA Dome C ice-core in Antarctica that spans the past 800 000 years. The temporal resolution is 5 years over the last 400 kyrs, and 25 years over the last 800 kyrs, enabling the detailed statistical analysis and comparison of eight glaciation cycles, and the subdivision of each cycle into eight consecutive phases. The unique span and resolution of the dataset allows us to analyze the macroweather and climate scales in detail, i.e. fluctuations with periodicities from 1 year to 100 000 years. We find that the interglacial and glacial maximum phases of each cycle showed particularly large macroweather to climate transition scale τc (around 2 kyrs), whereas mid-glacial phases feature centennial transition scales (average of 300 yr). This suggests that interglacials and glacial maxima are exceptionally stable when compared with the rest of a glacial cycle. The Holocene (with τc ≈ 7.9 kyrs) had a particularly large τc but it was not an outlier when compared with the phase 1 and 2 of other cycles. For each phase, we quantified the drift, intermittency, amplitude, and extremeness of the variability. Phases close to the interglacials (1, 2, 8) show low drift, moderate intermittency, and strong extremes, while the "glacial" middle phases 3–7 display strong drift, weak intermittency, and weaker extremes. Our results suggest that despite the large climatic changes occurring during glacial-interglacial transitions, glacial maxima, interglacials, and glacial inceptions were characterized by relatively stable atmospheric conditions, but punctuated by more frequent and severe droughts, than during the more unstable mid-glacial conditions. The low amplitude during phases 6–8 also suggests that the Patagonian ice sheet was not yet fully developed before 30 kyr after glacial inception.
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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 | 0.002 |
| 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) | 0.001 | 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".