On the Spatial and Temporal Variability of Atmospheric Heat Transport in a Hierarchy of Models

Messori, Gabriele; Geen, Ruth; Czaja, Arnaud

doi:10.1175/jas-d-16-0360.1

Cited by 16 publications

(22 citation statements)

References 49 publications

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“…The mean meridional circulation generally plays a marginal role and is on average weakly equatorward. Instances of constructive interference between the poleward transports driven by transient and stationary waves have been previously associated with heat and moisture transport to the high latitudes (Goss et al, ), as well as more meridionally oriented circulation regimes that divert synoptic systems poleward (Baggett et al, ) and large values of zonally integrated poleward energy transport (Messori et al, ). In this context, the decomposition presented here elucidates the contributions of the different groups of wavenumbers.…”

Section: Discussionmentioning

confidence: 91%

Spectral Decomposition and Extremes of Atmospheric Meridional Energy Transport in the Northern Hemisphere Midlatitudes

Lembo¹,

Messori²,

Graversen³

et al. 2019

Geophysical Research Letters

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The atmospheric meridional energy transport in the Northern Hemisphere midlatitudes is mainly accomplished by planetary and synoptic waves. A decomposition into wave components highlights the strong seasonal dependence of the transport, with both the total transport and the contributions from planetary and synoptic waves peaking in winter. In both winter and summer months, poleward transport extremes primarily result from a constructive interference between planetary and synoptic motions. The contribution of the mean meridional circulation is close to climatology. Equatorward transport extremes feature a mean meridional equatorward transport in winter, while the planetary and synoptic modes mostly transport energy poleward. In summer, a systematic destructive interference occurs, with planetary modes mostly transporting energy equatorward and synoptic modes again poleward. This underscores that baroclinic conversion dominates regardless of season in the synoptic wave modes, whereas the planetary waves can be either free or forced, depending on the season.

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Section: Discussionmentioning

confidence: 91%

Spectral Decomposition and Extremes of Atmospheric Meridional Energy Transport in the Northern Hemisphere Midlatitudes

Lembo¹,

Messori²,

Graversen³

et al. 2019

Geophysical Research Letters

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“…10 and 11. During the NAO1 and even more clearly during the NAO2, extremely strong zonal-mean synoptic heat flux develops in the form of a synchronized increase at several longitudinal sectors, a feature that is discussed by Messori and Czaja (2015) as a possible behavior of extremes of zonally integrated transient eddy heat flux in the midlatitudes. Another possibility is that the extreme synoptic heat flux during NAO6 is achieved via zonally confined pulses that are equally likely in several regions.…”

Section: Discussionmentioning

confidence: 99%

“…An evocative perspective is to combine the concept of a local effect of synoptic disturbances (Ambaum and Novak 2014) with the nature of strong zonal-mean transient eddy transport scattered in pulses at different latitudes (Messori et al 2017), through the idea that the transient synoptic flux happens at latitudes ''selected'' by a certain local flow regime. Low-frequency regimes on a large but not hemispheric scale affect the transient heat flux locally (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Extremes constitute an important component of the extratropical heat flux by transient eddies and a large fraction of the heat transport is attributable to few, extreme events (Messori and Czaja 2013). The skewness of the atmospheric heat flux in the extratropics is also discussed by Watt-Meyer and Kushner (2018).…”

Section: Synoptic Heat Flux Extremesmentioning

confidence: 99%

“…The works of Messori and Czaja (2013) and Messori and Czaja (2015) raised awareness of the impulsive and ''sporadic'' nature of high-and midlatitude transient eddy heat flux (including low frequencies), providing a picture of a highly variable field and noting that a few days can eventually explain most of the heat flux of a season. In particular, Messori and Czaja (2015) suggested a potential association between low-frequency variability of the storm tracks and pulses of eddy heat transport. Woods et al (2013) analyzed moisture intrusions into the Arctic during the 1990-2010 period in four sectors, namely, the Labrador Sea, the GIN (Greenland, Iceland, and Norwegian) seas, the Barents-Kara Seas, and the Pacific.…”

Section: Introductionmentioning

confidence: 99%

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North Atlantic Circulation Regimes and Heat Transport by Synoptic Eddies

et al. 2020

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Meridional transport of heat by transient atmospheric eddies is a key component of the energy budget of the middle- and high-latitude regions. The heat flux at relevant frequencies is also part of a dynamical interaction between eddies and mean flow. In this study we investigate how the poleward heat flux by high-frequency atmospheric transient eddies is modulated by North Atlantic weather regimes in reanalysis data. Circulation regimes are estimated via a clustering method, a jet-latitude index, and a blocking index. Heat transport is defined as advection of moist static energy. The focus of the analysis is on synoptic frequencies but results for slightly longer time scales are reported. Results show that the synoptic eddy heat flux is substantially modulated by midlatitude weather regimes on a regional scale in midlatitude and polar regions. In a zonal-mean sense, the phases of the North Atlantic Oscillation do not significantly change the high-latitude synoptic heat flux, whereas Scandinavian blocking and the Atlantic ridge are associated with an intensification. A close relationship between high-latitude (midlatitude) heat flux and Atlantic jet speed (latitude) is found. The relationship between extreme events of synoptic heat flux and circulation regimes is also assessed and reveals contrasting behaviors in the polar regions. The perspective that emerges complements the traditional view of the interaction between synoptic eddies and the extratropical flow and reveals relationships with the high-latitude climate.

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Nordic Seas Heat Loss, Atlantic Inflow, and Arctic Sea Ice cover over the last century

Smedsrud

Brakstad

Madonna

et al. 2021

Preprint

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Poleward ocean heat transport is a key process in the earth system. We detail and review the northward Atlantic Water (AW) flow, Arctic Ocean heat transport, and heat loss to the atmosphere since 1900 in relation to sea ice cover. Our synthesis is largely based on a sea ice-ocean model forced by a reanalysis atmosphere corroborated by a comprehensive hydrographic database (1950-), AW inflow observations (1996-), and other long-term time series of sea ice extent (1900-), glacier retreat (1984-), and Barents Sea hydrography (1900-). The Arctic Ocean, including the Nordic and Barents Seas, has warmed since the 1970s. This warming is congruent with increased ocean heat transport and sea ice loss and has contributed to the retreat of marine-terminating glaciers on Greenland. Heat loss to the atmosphere is largest in the Nordic Seas (60% of total) with large variability linked to the frequency of Cold Air Outbreaks and cyclones in the region, but there is no long-term statistically significant trend. Heat loss from the Barents Sea (∼30%) and Arctic seas farther north (∼10%) is overall smaller, but exhibit large positive trends. The AW inflow, total heat loss to the atmosphere, and dense outflow have all increased since 1900. These are consistently related through theoretical scaling, but the AW inflow increase is also wind-driven. The Arctic Ocean CO 2 uptake has increased by ∼30% over the last century-consistent with Arctic sea ice loss allowing stronger air-sea interaction and is ∼8% of the global uptake. Plain Language SummaryThe major flow to and from the Arctic Ocean occurs across the Greenland-Scotland Ridge. The inflow is mostly warm Atlantic Water (AW) flowing northwards and cooling gradually. After completing different loops within the Arctic Ocean, portions of this water eventually flows south as cold freshened polar water at the surface and cold, dense overflow water at depth. We review and synthesize how the AW cooling evolved over the last century in relation to the Arctic sea ice cover. In the mean 60% of the heat loss occurred in the Nordic Seas, 30% in the Barents Sea, and only 10% in the Arctic seas further north. Arctic sea ice decrease the last century created more open water and permitted stronger ocean heat loss. The ocean volume and heat transport also increased, consistently with increased heat loss, and increased wind forcing. Ocean temperatures have generally increased in many areas during the last 50 years, and on Greenland this drove the retreat of marine-terminating glaciers. Variability in ocean heat loss to the atmosphere was primarily driven by Cold Air Outbreaks and cyclones in the Nordic and Barents Seas, and explain variability in Arctic Ocean CO 2 uptake, being ∼8% of the global uptake.

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On the Spatial and Temporal Variability of Atmospheric Heat Transport in a Hierarchy of Models

Cited by 16 publications

References 49 publications

Spectral Decomposition and Extremes of Atmospheric Meridional Energy Transport in the Northern Hemisphere Midlatitudes

Spectral Decomposition and Extremes of Atmospheric Meridional Energy Transport in the Northern Hemisphere Midlatitudes

North Atlantic Circulation Regimes and Heat Transport by Synoptic Eddies

Nordic Seas Heat Loss, Atlantic Inflow, and Arctic Sea Ice cover over the last century

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