@article{Misios:2019:10.1073/pnas.1815060116,
author = {Misios, S and Gray, LJ and Knudsen, MF and Karoff, C and Schmidt, H and Haigh, JD},
doi = {10.1073/pnas.1815060116},
journal = {Proceedings of the National Academy of Sciences of USA},
pages = {7186--7191},
title = {Slowdown of the Walker circulation at solar cycle maximum},
url = {http://dx.doi.org/10.1073/pnas.1815060116},
volume = {116},
year = {2019}
}

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TY  - JOUR
AB  - The Pacific Walker Circulation (PWC) fluctuates on interannual and multidecadal timescales under the influence of internal variability and external forcings. Here, we provide observational evidence that the 11-y solar cycle (SC) affects the PWC on decadal timescales. We observe a robust reduction of east-west sea-level pressure gradients over the Indo-Pacific Ocean during solar maxima and the following 1-2 y. This reduction is associated with westerly wind anomalies at the surface and throughout the equatorial troposphere in the western/central Pacific paired with an eastward shift of convective precipitation that brings more rainfall to the central Pacific. We show that this is initiated by a thermodynamical response of the global hydrological cycle to surface warming, further amplified by atmosphere-ocean coupling, leading to larger positive ocean temperature anomalies in the equatorial Pacific than expected from simple radiative forcing considerations. The observed solar modulation of the PWC is supported by a set of coupled ocean-atmosphere climate model simulations forced only by SC irradiance variations. We highlight the importance of a muted hydrology mechanism that acts to weaken the PWC. Demonstration of this mechanism acting on the 11-y SC timescale adds confidence in model predictions that the same mechanism also weakens the PWC under increasing greenhouse gas forcing.
AU  - Misios,S
AU  - Gray,LJ
AU  - Knudsen,MF
AU  - Karoff,C
AU  - Schmidt,H
AU  - Haigh,JD
DO  - 10.1073/pnas.1815060116
EP  - 7191
PY  - 2019///
SN  - 0027-8424
SP  - 7186
TI  - Slowdown of the Walker circulation at solar cycle maximum
T2  - Proceedings of the National Academy of Sciences of USA
UR  - http://dx.doi.org/10.1073/pnas.1815060116
UR  - https://www.ncbi.nlm.nih.gov/pubmed/30926659
UR  - http://hdl.handle.net/10044/1/73981
VL  - 116
ER  - 

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