@article{ab9b21b7e39f42a2af50ae3b5baf2dc2,
title = "Cloud radiative feedbacks and El Ni{\~n}o-Southern Oscillation",
abstract = "Cloud radiative feedbacks are disabled via {"}cloud-locking{"} in the Community Earth System Model, version 1.2 (CESM1.2), to result in a shift in El Ni{\~n}o-Southern Oscillation (ENSO) periodicity from 2-7 years to decadal time scales. We hypothesize that cloud radiative feedbacks may impact the periodicity in three ways: by 1) modulating heat flux locally into the equatorial Pacific subsurface through negative shortwave cloud feedback on sea surface temperature anomalies (SSTA), 2) damping the persistence of subtropical southeast Pacific SSTA such that the South Pacific meridional mode impacts the duration of ENSO events, or 3) controlling the meridional width of off-equatorial westerly winds, which impacts the periodicity of ENSO by initiating longer Rossby waves. The result of cloud-locking in CESM1.2 contrasts that of another study, which found that cloud-locking in a different global climate model led to decreased ENSO magnitude across all time scales due to a lack of positive longwave feedback on the anomalous Walker circulation. CESM1.2 contains this positive longwave feedback on the anomalous Walker circulation, but either its influence on the surface is decoupled from ocean dynamics or the feedback is only active on interannual time scales. The roles of cloud radiative feedbacks in ENSO in other global climate models are additionally considered. In particular, it is shown that one cannot predict the role of cloud radiative feedbacks in ENSO through a multimodel diagnostic analysis. Instead, they must be directly altered.",
keywords = "Cloud radiative effects, Convection, ENSO, Tropics, Walker circulation",
author = "Middlemas, {Eleanor A.} and Clement, {Amy C.} and Brian Medeiros and Ben Kirtman",
note = "Funding Information: This research was supported by the National Science Foundation Graduate Research Fellowship Program (NSF GRFP). This work would not be possiblewithout the computational support and resources provided by the Computational Information Systems Laboratory (CISL) at National Center for Atmospheric Research (NCAR), as well as the various international modeling groups participating in CMIP5. NCAR is sponsored by the National Science Foundation. We express immense gratitude to Jerry Olsen for substantial help with implementing cloud-locking in CESM-this project would not exist without his efforts. We extend thanks to Thorsten Mauritsen for inspiring this experiment, answering many questions about cloud-locking, and openly sharing other cloud-locking experiments. Wealso thank the ClimateAnalysis Section at NCAR for extensive feedback that led to clearer plots. EM and AC were supported by National Oceanic and Atmospheric Administration (NOAA)GrantNA14OAR4310275.BM acknowledges support from the Regional and Global Climate Modeling Program of the U.S. Department of Energy, Office of Science, Cooperative Agreement DE-FC02-97ER62402. BK was supported by NSF Grant OCE1419561 and NOAA Grant NA15OAR4320064. Funding Information: Acknowledgments. This research was supported by the National Science Foundation Graduate Research Fellowship Program (NSF GRFP). This work would not be possible without the computational support and resources provided by the Computational Information Systems Laboratory (CISL) at National Center for Atmospheric Research (NCAR), as well as the various international modeling groups participating in CMIP5. NCAR is sponsored by the National Science Foundation. We express immense gratitude to Jerry Olsen for substantial help with implementing cloud-locking in CESM—this project would not exist without his efforts. We extend thanks to Thorsten Mauritsen for inspiring this experiment, answering many questions about cloud-locking, and openly sharing other cloud-locking experiments. We also thank the Climate Analysis Section at NCAR for extensive feedback that led to clearer plots. EM and AC were supported by National Oceanic and Atmospheric Administration (NOAA) Grant NA14OAR4310275. BM acknowledges support from the Regional and Global Climate Modeling Program of the U.S. Department of Energy, Office of Science, Cooperative Agreement DE-FC02-97ER62402. BK was supported by NSF Grant OCE1419561 and NOAA Grant NA15OAR4320064. Publisher Copyright: {\textcopyright} 2019 American Meteorological Society.",
year = "2019",
doi = "10.1175/JCLI-D-18-0842.1",
language = "English (US)",
volume = "32",
pages = "4661--4680",
journal = "Journal of Climate",
issn = "0894-8755",
publisher = "American Meteorological Society",
number = "15",
}