The Arctic oscillation signature in the wintertime geopotential height and temperature fields

Thompson, David W. J.; Wallace, John M.

doi:10.1029/98gl00950

Cited by 3,580 publications

(3,073 citation statements)

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“…During the late 1980s and early 1990s, the leading mode of hemispheric surface atmospheric pressure, the Arctic Oscillation (AO; Thompson and Wallace 1998), entered an extreme positive phase. Positive AO is expressed as low surface atmospheric pressure over the Arctic Ocean.…”

Section: Introductionmentioning

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: Introductionmentioning

confidence: 99%

Arctic Ocean Circulation Patterns Revealed by GRACE

et al. 2014

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“…A common conceptual model of upper Arctic Ocean variability entails a switch between strong and weak states of the Beaufort Gyre and the Transpolar Drift on near-decadal timescales (see the review by Mauritzen, 2012). However, the influence of the atmospheric circulation on the Arctic ocean at different timescales is still a subject of ongoing research, as there are different patterns from decadal to interannual timescales (Thompson and Wallace, 1998;Zhang et al, 2008). In addition, there is evidence of a strong influence of regional atmospheric variability on regional freshwater release and advection; for example, the shelf-basin exchange at the Siberian continental slope (Bauch et al, 2011a;Jahn et al, 2010) or Ekman Pumping induced by wind stress in the Amerasian Basin (Rabe et al, 2011).…”

Section: Arctic Upper Ocean and Atmosphere Variabilitymentioning

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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“…The monthly Arctic Oscillation index was used as the index of NAM, which is available with its definition (Thompson and Wallace 1998) at http://www.cpc.ncep.noaa.gov/products/precip/ CWlink/daily_ao_index/ao.shtml.…”

Section: Methodsmentioning

confidence: 99%

“…Many works have reported the dominant wintertime atmospheric teleconnection patterns over the Northern Hemisphere (NH) (Wallace and Gutzler 1981;Barnston and Livezey 1987): (1) the North Pacific Oscillation (NPO), (2) the North Atlantic Oscillation, (3) the Pacific/North American (PNA) pattern, and (4) the Northern Hemisphere annular mode (NAM) (Thompson and Wallace 1998). Smoliak and Wallace (2015) also classified such teleconnection patterns in sea level pressure (SLP) into three categories: (1) NAM, (2) PNA, and (3) local monopole patterns that encircle along the coastline of the Arctic Ocean.…”

Section: Introductionmentioning

confidence: 99%

A Precursor of the Monthly-Mean Large-Scale Atmospheric Circulation Anomalies over the North Pacific

Tomita

Yamaura

2017

SOLA

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The North Pacific shows dominant monthly-mean largescale atmospheric circulation anomalies, even after removing the variabilities of the Northern Hemisphere annular mode and the El Niño/Southern Oscillation. This work examines the precursors and their development for these residual anomalous circulations by applying objective reanalysis data to empirical orthogonal function (EOF) analysis. The first EOF mode (EOF1) features a monopole, while a dipole characterizes the second EOF mode (EOF2) over the North Pacific. Transient eddies (TEs) interactively induce the two EOF modes.The precursors of EOF1 and EOF2 are detected in the anomalies of one month earlier; these are the systematic zonal bands detected in surface temperature and baroclinic instability (BI) in the lower troposphere over Eurasia and North America. The BI anomalies further extend into the central North Pacific at different latitudes between EOF1 and EOF2. Coherent zonal bands also appear in the geopotential height anomalies of upper troposphere. Such zonal bands reflect the ovalization of Arctic circumpolar circulation with different continent-ward shifts of the longer axis. The direction of this shift determines which EOF mode develops by the following month through the guided activation of TEs at a designated latitude over the North Pacific.(Citation: Tomita, T., and T. Yamaura, 2017: A precursor of the monthly-mean large-scale atmospheric circulation anomalies over the North Pacific. SOLA, 13, 85−89,

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The Arctic oscillation signature in the wintertime geopotential height and temperature fields

Cited by 3,580 publications

References 27 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

A Precursor of the Monthly-Mean Large-Scale Atmospheric Circulation Anomalies over the North Pacific

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