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

Abstract

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 totalmore » 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.« less

Authors:
; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1340786
Report Number(s):
PNNL-SA-115660
Journal ID: ISSN 0894-8755; KP1703010
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Climate; Journal Volume: 29; Journal Issue: 18
Country of Publication:
United States
Language:
English
Subject:
atmospheric rivers; CMIP5; jet position; RCP 8.5; extreme precipitation

Citation Formats

Gao, Yang, Lu, Jian, and Leung, L. Ruby. Uncertainties in Projecting Future Changes in Atmospheric Rivers and Their Impacts on Heavy Precipitation over Europe. United States: N. p., 2016. Web. doi:10.1175/JCLI-D-16-0088.1.
Gao, Yang, Lu, Jian, & Leung, L. Ruby. Uncertainties in Projecting Future Changes in Atmospheric Rivers and Their Impacts on Heavy Precipitation over Europe. United States. doi:10.1175/JCLI-D-16-0088.1.
Gao, Yang, Lu, Jian, and Leung, L. Ruby. Thu . "Uncertainties in Projecting Future Changes in Atmospheric Rivers and Their Impacts on Heavy Precipitation over Europe". United States. doi:10.1175/JCLI-D-16-0088.1.
@article{osti_1340786,
title = {Uncertainties in Projecting Future Changes in Atmospheric Rivers and Their Impacts on Heavy Precipitation over Europe},
author = {Gao, Yang and Lu, Jian and Leung, L. Ruby},
abstractNote = {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.},
doi = {10.1175/JCLI-D-16-0088.1},
journal = {Journal of Climate},
number = 18,
volume = 29,
place = {United States},
year = {Thu Sep 01 00:00:00 EDT 2016},
month = {Thu Sep 01 00:00:00 EDT 2016}
}