Baroclinic Annular Mode Modulates Global Atmospheric Rivers and Extreme Precipitation
Abstract
The Baroclinic Annular Mode (BAM) strongly influences extratropical circulation, yet its role in the global hydrological cycle remains unclear. Using ERA5 reanalysis and a global atmospheric river (AR) database, we show that BAM systematically reorganizes AR occurrence and extreme precipitation in both hemispheres. During high-BAM states, AR frequency increases along the flanks of major storm tracks and decreases near their climatological cores, redistributing preferred AR corridors. Relative AR-frequency changes locally exceed 50%, with the most zonally coherent patterns over the Southern Ocean. Extreme precipitation varies correspondingly, with 99th-percentile precipitation occurrence increasing by more than 50% across broad poleward storm-track regions. A large fraction of these extremes coincide with ARs, and AR-associated extreme precipitation shows similar BAM-related modulations. Low-BAM states show broadly opposite anomalies. These results identify BAM as a key mode linking large-scale circulation to global moisture transport and hydrological extremes.
Related
- Climate models lack decadal variability in precipitation because of a weak atmospheric response to sea surface temperature anomalies
- Trade-offs between predictive accuracy and distributional fidelity in surrogate modeling of extreme precipitation
- Polar front jet regulates tropical sea surface temperature impacts on South China extreme precipitation
- Bay of Bengal cyclones fuel non-monsoon extreme precipitation on the central Tibetan Plateau
- Hysteresis of extreme precipitation in East Asia under various CO2 removal pathways
BibTeX
@misc{zhao2026baroclinic,
title = {{Baroclinic Annular Mode Modulates Global Atmospheric Rivers and Extreme Precipitation}},
author = {Yuan-Bing Zhao and Lei Wang and Yi Ming},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.33072},
eprint = {2609.33072},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.33072},
}
RIS
TY - UNPB
TI - Baroclinic Annular Mode Modulates Global Atmospheric Rivers and Extreme Precipitation
AU - Yuan-Bing Zhao
AU - Lei Wang
AU - Yi Ming
PY - 2026
DA - 2026/09/27
PB - arXiv
DO - 10.48550/arxiv.2609.33072
UR - https://arxiv.org/abs/2609.33072
AB - The Baroclinic Annular Mode (BAM) strongly influences extratropical circulation, yet its role in the global hydrological cycle remains unclear. Using ERA5 reanalysis and a global atmospheric river (AR) database, we show that BAM systematically reorganizes AR occurrence and extreme precipitation in both hemispheres. During high-BAM states, AR frequency increases along the flanks of major storm tracks and decreases near their climatological cores, redistributing preferred AR corridors. Relative AR-frequency changes locally exceed 50%, with the most zonally coherent patterns over the Southern Ocean. Extreme precipitation varies correspondingly, with 99th-percentile precipitation occurrence increasing by more than 50% across broad poleward storm-track regions. A large fraction of these extremes coincide with ARs, and AR-associated extreme precipitation shows similar BAM-related modulations. Low-BAM states show broadly opposite anomalies. These results identify BAM as a key mode linking large-scale circulation to global moisture transport and hydrological extremes.
ER -