Uncertainties in Projecting Future Changes in Atmospheric Rivers and Their Impacts on Heavy Precipitation over Europe

Journal Article · Thu Sep 01 04:00:00 EDT 2016 · Journal of Climate

DOI:https://doi.org/10.1175/JCLI-D-16-0088.1· OSTI ID:1340786

Gao, Yang; Lu, Jian; Leung, L. Ruby

This study investigates the North Atlantic atmospheric rivers (ARs) making landfall over western Europe in the present and future climate from the multi-model ensemble of the Coupled Model Intercomparison Project Phase 5 (CMIP5). Overall, CMIP5 captures the seasonal and spatial variations of historical landfalling AR days, with the large inter-model variability strongly correlated with the inter-model spread of historical jet position. Under RCP 8.5, AR frequency is projected to increase a few times by the end of this century. While thermodynamics plays a dominate role in the future increase of ARs, wind changes associated with the midlatitude jet shifts also significantly contribute to AR changes, resulting in dipole change patterns in all seasons. In the North Atlantic, the model projected jet shifts are strongly correlated with the simulated historical jet position. As models exhibit predominantly equatorward biases in the historical jet position, the large poleward jet shifts reduce AR days south of the historical mean jet position through the dynamical connections between the jet positions and AR days. Using the observed historical jet position as an emergent constraint, dynamical effects further increase AR days in the future above the large increases due to thermodynamical effects. In the future, both total and extreme precipitation induced by AR contribute more to the seasonal mean and extreme precipitation compared to present primarily because of the increase in AR frequency. While AR precipitation intensity generally increases more relative to the increase in integrated vapor transport, AR extreme precipitation intensity increases much less.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1340786
• Report Number(s): PNNL-SA-115660; KP1703010
• Journal Information: Journal of Climate, Journal Name: Journal of Climate Journal Issue: 18 Vol. 29; ISSN 0894-8755
• Publisher: American Meteorological Society
• Country of Publication: United States
• Language: English

Related Subjects

CMIP5
RCP 8.5
atmospheric rivers
extreme precipitation
jet position