• Clarke, R. A., , and J. C. Gascard, 1983: The formation of Labrador Sea Water. Part I: Large-scale processes. J. Phys. Oceanogr, 13 , 17641778.

    • Search Google Scholar
    • Export Citation
  • Da Silva, A. M., , C. C. Young, , and S. Levitus, cited. . 1995: Atlas of Surface Marine Data 1994. Vol. 1: Algorithms and Procedures, [Available online at http://ferret.wrc.noaa.gov/LAS/doc_htmls/surface_marine_sst_clm.cdf.html.].

    • Search Google Scholar
    • Export Citation
  • Diaz, H. F., , C. S. Ramage, , S. D. Woodruff, , and T. S. Parker, 1987: Climatic Summaries of Ocean Weather Stations. U.S. Department of Commerce, 48 pp.

    • Search Google Scholar
    • Export Citation
  • Dorman, C. E., , and R. H. Bourke, 1978: A temperature correction for Tucker's ocean rainfall estimates. Quart. J. Roy. Meteor. Soc., 104 , 765773.

    • Search Google Scholar
    • Export Citation
  • Gascard, J. C., , and R. A. Clarke, 1983: The formation of Labrador Sea Water. Part II: Mesoscale and smaller-scale processes. J. Phys. Oceanogr., 13 , 17791797.

    • Search Google Scholar
    • Export Citation
  • GHCC, cited 1998: A NOAA/NASA TOVS pathfinder path C1 product: MSU temperatures and rainfall. Global Hydrology and Climate Center Rep. [Available online at http://ghrc.msfc.nasa.gov/uso/readme/tovs.html.].

    • Search Google Scholar
    • Export Citation
  • Gill, A. E., 1982: Atmosphere–Ocean Dynamics. Academic Press, 662 pp.

  • Huo, Z., , D-L. Zhang, , and J. Gyakum, 1996a: The life-cycle of the intense IOP-14 storm during CASP II. Part I: Analysis and simulations. Atmos.–Ocean, 34 , 5180.

    • Search Google Scholar
    • Export Citation
  • Huo, Z., , D-L. Zhang, , and J. Gyakum, . 1996b: The life-cycle of the intense IOP-14 storm during CASP II. Part II: Sensitivity experiments. Atmos.–Ocean, 34 , 81102.

    • Search Google Scholar
    • Export Citation
  • Hurrell, J. W., 1995: Decadal trends in the North Atlantic Oscillation: Regional temperatures and precipitation. Science, 269 , 676679.

    • Search Google Scholar
    • Export Citation
  • Kalnay, E., and Coauthors. 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc., 77 , 437471.

  • Kwok, R., , and D. A. Rothrock, 1999: Variability of Fram Strait ice flux and North Atlantic Oscillation. J. Geophys. Res., 104 , 51775189.

    • Search Google Scholar
    • Export Citation
  • Lab Sea Group, 1998: The Labrador Sea Deep Convection Experiment. Bull. Amer. Meteor. Soc., 79 , 20332058.

  • Lazier, J. N. R., 1980: Oceanographic conditions at Ocean Weather Ship Bravo, 1964–1974. Atmos.–Ocean, 18 , 227238.

  • Legates, D. R., , and C. J. Willmott, 1990: Mean seasonal and spatial variability in gauge-corrected, global precipitation. Int. J. Climatol., 10 , 111127.

    • Search Google Scholar
    • Export Citation
  • Lin, H., , and J. Derome, 1998: A three-year lagged correlation between the North Atlantic Oscillation and winter conditions over the North Pacific and North America. Geophys. Res. Lett., 25 , 28292832.

    • Search Google Scholar
    • Export Citation
  • Marshall, J., , and F. Schott, 1999: Open-ocean convection: Observations, theory and models. Rev. Geophys., 37 , 164.

  • Moore, G. W. K., , M. C. Reader, , J. York, , and S. Sathiyamoorthy, 1996: Polar lows in the Labrador Sea. A case study. Tellus, 48A , 1740.

    • Search Google Scholar
    • Export Citation
  • Moore, G. W. K., , K. Alverson, , and X. Huo, . 2001: Spatial and temporal variability in the heat and freshwater fluxes associated with the passage of cyclone over the Labrador Sea. J. Geophys. Res., in press.

    • Search Google Scholar
    • Export Citation
  • Pagowski, M., , and G. W. K. Moore, 2001: A numerical study of an extreme cold-air outbreak over the Labrador Sea: Sea ice, air–sea interaction, and development of polar lows. Mon. Wea. Rev., 129 , 4772.

    • Search Google Scholar
    • Export Citation
  • Rassmussen, E. A., , C. Claud, , and J. F. Purdom, 1996: Labrador Sea polar lows. Global Atmos. Ocean Syst., 4 , 275334.

  • Reed, R. J., , A. J. Simmons, , M. D. Albright, , and P. Unden, 1988: The role of latent heat release in explosive cyclogenesis: Three examples based on ECMWF operational forecasts. Wea. Forecasting, 3 , 217229.

    • Search Google Scholar
    • Export Citation
  • Renfrew, I. A., , and G. W. K. Moore, 1999: An extreme cold-air outbreak over the Labrador Sea: Roll vorticies and air–sea interaction. Mon. Wea. Rev., 127 , 23792394.

    • Search Google Scholar
    • Export Citation
  • Rogers, J. C., 1984: Association between the North Atlantic Oscillation and the Southern Oscillation in the Northern Hemisphere. Mon. Wea. Rev., 112 , 19992015.

    • Search Google Scholar
    • Export Citation
  • Smith, S. D., , and F. W. Dobson, 1984: The heat budget at Ocean Weather Station Bravo. Atmos.–Ocean, 22 , 122.

  • Spencer, R. W., 1993: Global oceanic precipitation from the MSU during 1979–91 and comparisons to other climatologies. J. Climate, 6 , 13011326.

    • Search Google Scholar
    • Export Citation
  • Tucker, G. B., 1961: Precipitation over the North Atlantic. Quart. J. Roy. Meteor. Soc., 87 , 147158.

  • van Loon, H., , and J. C. Rogers, 1978: The seesaw in winter temperatures between Greenland and Northern Europe. Part I: General description. Mon. Wea. Rev., 106 , 296310.

    • Search Google Scholar
    • Export Citation
  • Woodruff, S. D., 1987: Comprehensive Ocean–Atmosphere Data Set. Bull. Amer. Meteor. Soc., 68 , 12391250.

  • Xie, P., , and P. A. Arkin, 1997: Global precipitation: A 17-year monthly analysis based on gauge observations, satellite estimates, and numerical model outputs. Bull. Amer. Meteor. Soc., 78 , 25392558.

    • Search Google Scholar
    • Export Citation
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Buoyancy Flux at Ocean Weather Station Bravo

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  • 1 Department of Physics, University of Toronto, Toronto, Ontario, Canada
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Abstract

Deep water formation at high latitudes is believed to be the driving mechanism behind the ocean's thermohaline circulation. The exchange of heat and water with the atmosphere causes the density of the surface waters to change, with subsequent downwelling and upwelling resulting as the system relaxes toward convective equilibrium. The characteristics of this atmosphere–ocean exchange are examined by studying the temporal variability of the buoyancy flux at OWS Bravo, a location where deep water formation is known to occur. The authors find that there is significant high-frequency variability in the buoyancy flux attributable to the passage of synoptic weather systems, variability that is masked by monthly analyses. At high latitudes, precipitation plays a significant role in the buoyancy flux. If it is ignored, the buoyancy loss is overestimated (positive coordinate is downward). Precipitation also causes the buoyancy flux to become positive during the passage of a cyclone. The timescale for this change in buoyancy flux is found to be similar to the timescale for the convective plumes in the ocean, suggesting a link between the two. In addition, a strong negative correlation is found to exist between the sensible heat flux at Bravo and the North Atlantic Oscillation.

Corresponding author address: Dr. S. Sathiyamoorthy, Dept. of Physics, University of Toronto, 60 St. George Street, Rm. 619, Toronto, ON M5S 1A7, Canada. Email: sathy@atmosp.physics.utoronto.ca

Abstract

Deep water formation at high latitudes is believed to be the driving mechanism behind the ocean's thermohaline circulation. The exchange of heat and water with the atmosphere causes the density of the surface waters to change, with subsequent downwelling and upwelling resulting as the system relaxes toward convective equilibrium. The characteristics of this atmosphere–ocean exchange are examined by studying the temporal variability of the buoyancy flux at OWS Bravo, a location where deep water formation is known to occur. The authors find that there is significant high-frequency variability in the buoyancy flux attributable to the passage of synoptic weather systems, variability that is masked by monthly analyses. At high latitudes, precipitation plays a significant role in the buoyancy flux. If it is ignored, the buoyancy loss is overestimated (positive coordinate is downward). Precipitation also causes the buoyancy flux to become positive during the passage of a cyclone. The timescale for this change in buoyancy flux is found to be similar to the timescale for the convective plumes in the ocean, suggesting a link between the two. In addition, a strong negative correlation is found to exist between the sensible heat flux at Bravo and the North Atlantic Oscillation.

Corresponding author address: Dr. S. Sathiyamoorthy, Dept. of Physics, University of Toronto, 60 St. George Street, Rm. 619, Toronto, ON M5S 1A7, Canada. Email: sathy@atmosp.physics.utoronto.ca

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