Circulation and convection in the Irminger Sea

Våge, Kjetil

doi:10.1575/1912/3218

Cited by 1 publication

(4 citation statements)

References 142 publications

(373 reference statements)

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“…The third EOF mode resembles the ridge regime in Cassou et al [2004]. It is also connected to the Greenland blocking as defined by Scherrer et al [2006] and a northern jet stream location [Woollings et al, 2008, 2010, Hannachi et al, 2012, which is in turn associated with a negative phase of the East Atlantic pattern [Barnston and Livezey, 1987]. This EOF mode shows similarity with the stationary topographic Rossby wave pattern over the southeast Greenland coast, SLP variance over Greenland.…”

Section: Topographic Forcingmentioning

confidence: 72%

“…Mean turbulent heat fluxes during DWE are ∼-400 W m −2 which is of the same order of magnitude as the turbulent heat fluxes that occur during tip jet events [Våge et al, 2009, Vage, 2010, Pickart et al, 2003a. However, the region of maximum heat loss during tip jets is shifted southward compared to that during DWE as is the cyclone that is forcing DWE.…”

Section: Impacts Downstream Buoyancy Fluxmentioning

confidence: 93%

“…Next, I represent the geostrophic wind and the vorticity in terms of the perturbation streamfunction Ψ and approximate the smoothed topography with a Fourier series ℎ ( , ) = ∑︀ ∑︀ĥ , exp ( + ), whereĥ , are the Fourier coefficients. This has as steady-state solution [Charney andEliassen, 1949, Holton andHakim, 2013]: [Woollings et al, 2008, 2010, Hannachi et al, 2012.…”

Section: Topographic Forcingmentioning

confidence: 99%

“…The Irminger Sea, downstream of the valley, is an important ocean convection site [Pickart et al, 2003b, Vage, 2010, and thus part of the Meridional Overturning Circulation [Jungclaus et al, 2005, Stouffer et al, 2006 that influences the climate of northwest Europe [Vellinga and Wood, 2002]. Deep ocean convection is an intermittent phenomenon that is triggered by intense winter storms which force large buoyancy losses [Marshall and Schott, 1999].…”

Section: Introductionmentioning

confidence: 99%

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Strong wind events across Greenland�s coast and their influence on the ice sheet, sea ice and ocean

Oltmanns¹

2015

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In winter, Greenland's coastline adjacent to the subpolar North Atlantic and Nordic Seas is characterized by a large land-sea temperature contrast. Therefore, winds across the coast advect air across a horizontal temperature gradient and can result in significant surface heat fluxes both over the ice sheet (during onshore winds) and over the ocean (during offshore winds). Despite their importance, these winds have not been investigated in detail, and this thesis includes the first comprehensive study of their characteristics, dynamics and impacts. Using an atmospheric reanalysis, observations from local weather stations, and remote sensing data, it is suggested that high-speed wind events across the coast are triggered by the superposition of an upper level potential vorticity anomaly on a stationary topographic Rossby wave over Greenland, and that they intensify through baroclinic instability. Onshore winds across Greenland's coast can result in increased melting, and offshore winds drive large heat losses over major ocean convection sites.Strong offshore winds across the southeast coast are unique over Greenland, because the flow is funneled from the vast ice sheet inland into the narrow valley of Ammassalik at the coast, where it can reach hurricane intensity. In this region, the cold air, which formed over the northern ice sheet, is suddenly released during intense downslope wind events and spills over the Irminger Sea where the cold and strong winds can drive heat fluxes of up to 1000 W m −2 , with potential implications for deep water formation. Moreover, the winds advect sea ice away from the coast and out of a major glacial fjord.Simulations of these wind events in Ammassalik with the atmospheric Weather Research and Forecast Model show that mountain wave dynamics contribute to the acceleration of the downslope flow. In order to capture these dynamics, a high model 3 resolution with a detailed topography is needed. The effects of using a different resolution locally in the valley extend far downstream over the Irminger Sea, which has implications for the evolution and distribution of the heat fluxes.

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