Beaufort Gyre freshwater reservoir: State and variability from observations

Proshutinsky, Andrey; Krishfield, Richard A.; Timmermans, Mary‐Louise; Toole, John M.; Carmack, Eddy C.; McLaughlin, Fiona A.; Williams, William J.; Zimmermann, Sarah; Itoh, Motoyo; Shimada, Koji

doi:10.1029/2008jc005104

Cited by 428 publications

(641 citation statements)

References 59 publications

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“…Analogously, satellite altimetry with a polar orbit (e.g., Cryosat-2, or formerly ICESat) may be used to identify changes in the circulation that is dominated by barotropic motion. In those locations where the ocean circulation is predominantly barotropic through all time scales (i.e., the Chukchi, East Siberian, and Laptev Seas), a longer record of GRACE would be fundamental to study the trend in SSH as reported by Proshutinsky et al (2009) using available tide gauges. The sparseness of the tide gauge data in space and time has made this trend difficult to investigate in the past.…”

Section: Discussionmentioning

confidence: 99%

Arctic Ocean Circulation Patterns Revealed by GRACE

et al. 2014

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Measurements of ocean bottom pressure (OBP) anomalies from the satellite mission Gravity Recovery and Climate Experiment (GRACE), complemented by information from two ocean models, are used to investigate the variations and distribution of the Arctic Ocean mass from 2002 through 2011. The forcing and dynamics associated with the observed OBP changes are explored. Major findings are the identification of three primary temporal-spatial modes of OBP variability at monthly-to-interannual time scales with the following characteristics. Mode 1 (50% of the variance) is a wintertime basin-coherent Arctic mass change forced by southerly winds through Fram Strait, and to a lesser extent through Bering Strait. These winds generate northward geostrophic current anomalies that increase the mass in the Arctic Ocean. Mode 2 (20%) reveals a mass change along the Siberian shelves, driven by surface Ekman transport and associated with the Arctic Oscillation. Mode 3 (10%) reveals a mass dipole, with mass decreasing in the Chukchi, East Siberian, and Laptev Seas, and mass increasing in the Barents and Kara Seas. During the summer, the mass decrease on the East Siberian shelves is due to the basin-scale anticyclonic atmospheric circulation that removes mass from the shelves via Ekman transport. During the winter, the forcing mechanisms include a large-scale cyclonic atmospheric circulation in the eastern-central Arctic that produces mass divergence into the Canada Basin and the Barents Sea. In addition, strengthening of the Beaufort high tends to remove mass from the East Siberian and Chukchi Seas. Supporting previous modeling results, the month-to-month variability in OBP associated with each mode is predominantly of barotropic character.

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Section: Discussionmentioning

confidence: 99%

Arctic Ocean Circulation Patterns Revealed by GRACE

et al. 2014

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“…The most Pacific Water was found in 1998 and none in 2004 and 2005. This has been linked to temporary changes in the pathways of Pacific Water (Falck et al, 2005) and the strength of the Beaufort Gyre (Proshutinsky et al, 2009). As fractions of net sea ice melt were largely negative in all sections, this water mass in the outflow from the Arctic was most strongly influenced by brine from ice formation.…”

Section: Liquid Freshwater Components In the Western Fram Straitmentioning

confidence: 99%

“…Further studies of individual liquid freshwater components include the link of low FPW transports after 1998 and changes in the extent and the pathways of PW in the Arctic basins; in particular, a climate model simulation has shown that the pathways of PW exports from the Arctic are strongly related to the strength of the Beaufort Gyre (Jahn et al, 2010). Proshutinsky et al (2009) (2007) further suggest variability of the occurrence of PW in the Transpolar Drift on timescales of two or more years, shorter than the variability in the large-scale atmospheric circulation as represented by the Arctic Oscillation index (e.g. Thompson and Wallace, 1998).…”

Section: Changes In the Arctic Ocean Basinsmentioning

confidence: 99%

Liquid export of Arctic freshwater components through the Fram Strait 1998–2011

et al. 2013

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Abstract. We estimated the magnitude and composition of southward liquid freshwater transports in the East Greenland Current near 79 • N in the Western Fram Strait between 1998 and 2011. Previous studies have found this region to be an important pathway for liquid freshwater export from the Arctic Ocean to the Nordic Seas and the North Atlantic subpolar gyre.Our transport estimates are based on six hydrographic surveys between June and September and concurrent data from moored current meters. We combined concentrations of liquid freshwater, meteoric water (river water and precipitation), sea ice melt and brine from sea ice formation, and Pacific Water, presented in Dodd et al. (2012), with volume transport estimates from an inverse model. The average of the monthly snapshots of southward liquid freshwater transports between 10.6 • W and 4 • E is 100 ± 23 mSv (3160 ± 730 km 3 yr −1 ), relative to a salinity of 34.9. This liquid freshwater transport consists of about 130 % water from rivers and precipitation (meteoric water), 30 % freshwater from the Pacific, and −60 % (freshwater deficit) due to a mixture of sea ice melt and brine from sea ice formation.Pacific Water transports showed the highest variation in time, effectively vanishing in some of the surveys. Comparison of our results to the literature indicates that this was due to atmospherically driven variability in the advection of Pacific Water along different pathways through the Arctic Ocean. Variations in most liquid freshwater component transports appear to have been most strongly influenced by changes in the advection of these water masses to the Fram Strait. However, the local dynamics represented by the volume transports influenced the liquid freshwater component transports in individual years, in particular those of sea ice melt and brine from sea ice formation.Our results show a similar ratio of the transports of meteoric water and net sea ice melt as previous studies.

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“…Field observations and results of a 1-D boundary layer model for developing near-surface temperature maxima in the Western Arctic Proshutinsky et al, 2009;Yamamoto-Kawai et al, 2009). This freshening decreases the thickness of the surface mixed layer as turbulent length scales decrease under the effects of stabilizing buoyancy fluxes (McPhee, 1994).…”

Section: Research Articlementioning

confidence: 99%

“…Therefore, a variable depth control volume was used based on the 1022 kg m -3 isopycnal near the base of the surface mixed layer (magenta line on Figure 4b). To calculate surface freshwater input, we used the freshwater content equation (Rudels et al, 2004;Proshutinsky et al, 2009) [ ]…”

Section: Nstm Heat Content and Upper Ocean Freshwater Storagementioning

confidence: 99%

Field observations and results of a 1-D boundary layer model for developing near-surface temperature maxima in the Western Arctic

Gallaher

Stanton

Shaw

et al. 2017

Elementa: Science of the Anthropocene

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Gallaher, SG et al 2017 Field observations and results of a 1-D boundary layer model for developing near-surface temperature maxima in the Western Arctic. Elem Sci Anth, 5: 11, pp. 1-21, DOI: https://doi.org/10.1525/elementa.195 IntroductionRecent changes in the Arctic ice-ocean system have led to an increase in upper ocean heating. The primary source of this heating is the two-fold rise in ocean-absorbed solar radiation (Perovich et al., 2007) that results from rapidly declining summer sea ice extent (Comiso et al., 2008;Steele et al., 2010). Recent studies in the Canada Basin show that this absorbed solar heating is partitioned 0.23/0.77 between ocean heat storage and latent heat loss (basal ice melt), respectively (Toole et al., 2010;Gallaher et al., 2016). Most of the oceanic heat is accumulated in near-surface temperature maximum (NSTM) features. The NSTM is defined as an upper ocean (< 50 m) temperature maximum that: 1) is at least 0.2°C above freezing (δT); 2) has a salinity < 31; and 3) resides above a cooler water layer by at least 0.1°C (Jackson et al., 2010). Jackson et al. (2010) attribute NSTM development to the absorption of solar radiation in shallow, stratified layers beneath melting sea ice and open water during summer. Steele et al. (2011) present an additional formation process caused by cooling of the near-surface ocean under open water areas in late summer, which leaves behind a warmer subsurface layer. Although NSTM heat is gained in the summer, the release of this heat often occurs in later seasons. Observations in the Canada Basin show that the NSTM often survives into fall, and that heat from this layer can be mixed into the surface mixed layer to delay or slow freeze up (Steele et al., 2008;Jackson et al., 2010;Steele et al., 2011;Timmermans, 2015).Early studies of the NSTM during AIDJEX (Maykut and McPhee, 1995) and SHEBA (McPhee et al., 1998) found that the layer was present directly below the summer surface mixed layer, at depths between 25 and 35 m. However, the Canada Basin upper ocean is freshening (McPhee et al., 2009) Summer sea ice extent in the Western Arctic has decreased significantly in recent years resulting in increased solar input into the upper ocean. Here, a comprehensive set of in situ shipboard, on-ice, and autonomous ice-ocean measurements were made of the early stages of formation of the near-surface temperature maximum (NSTM) in the Canada Basin. These observations along with the results from a 1-D turbulent boundary layer model indicate that heat storage associated with NSTM formation is largely due to the absorption of penetrating solar radiation just below a protective summer halocline. The depth of the summer halocline was found to be the most important factor for determining the amount of solar radiation absorbed in the NSTM layer, while halocline strength controlled the amount of heat removed from the NSTM by turbulent transport. Observations using the Naval Postgraduate School Turbulence Frame show that the NSTM was able to persist despite periods of i...

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Beaufort Gyre freshwater reservoir: State and variability from observations

Cited by 428 publications

References 59 publications

Arctic Ocean Circulation Patterns Revealed by GRACE

Arctic Ocean Circulation Patterns Revealed by GRACE

Liquid export of Arctic freshwater components through the Fram Strait 1998–2011

Field observations and results of a 1-D boundary layer model for developing near-surface temperature maxima in the Western Arctic

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