Enhanced Wind-Driven Downwelling Flow in Warm Oceanic Eddy Features during the Intensification of Tropical Cyclone Isaac (2012): Observations and Theory

被引:78
作者
Jaimes, Benjamin [1 ]
Shay, Lynn K. [1 ]
机构
[1] Univ Miami, Rosenstiel Sch Marine & Atmospher Sci, Dept Ocean Sci, Miami, FL 33149 USA
关键词
Circulation; Dynamics; Atmosphere-ocean interaction; Eddies; Upwelling; downwelling; Wind stress; Atm; Ocean Structure; Phenomena; Hurricanes; typhoons; Oceanic mixed layer; HURRICANE BOUNDARY-LAYER; CURRENT RESPONSE; ENERGY RESPONSE; WAVE WAKE; PART I; FLUXES; KATRINA; BUDGET; MODEL; WATER;
D O I
10.1175/JPO-D-14-0176.1
中图分类号
P7 [海洋学];
学科分类号
0707 ;
摘要
Tropical cyclones (TCs) typically produce intense oceanic upwelling underneath the storm's center and weaker and broader downwelling outside upwelled regions. However, several cases of predominantly downwelling responses over warm, anticyclonic mesoscale oceanic features were recently reported, where the ensuing upper-ocean warming prevented significant cooling of the sea surface, and TCs rapidly attained and maintained major status. Elucidating downwelling responses is critical to better understanding TC intensification over warm mesoscale oceanic features. Airborne ocean profilers deployed over the Gulf of Mexico's eddy features during the intensification of tropical storm Isaac into a hurricane measured isothermal downwelling of up to 60 m over a 12-h interval (5 m h(-1)) or twice the upwelling strength underneath the storm's center. This displacement occurred over a warm-core eddy that extended underneath Isaac's left side, where the ensuing upper-ocean warming was similar to 8 kW m(-2); sea surface temperatures >28 degrees C prevailed during Isaac's intensification. Rather than with just Ekman pumping W-E, these observed upwelling-downwelling responses were consistent with a vertical velocity W-s = W-E - Ro(g)(U-h + U-OML); W-s is the TC-driven pumping velocity, derived from the dominant vorticity balance that considers geostrophic flow strength (measured by the eddy Rossby number Ro(g) = (g)/f), geostrophic vorticity (g), Coriolis frequency f, aspect ratio = h/R-max, oceanic mixed layer thickness h, storm's radius of maximum winds R-max, total surface stresses from storm motion U-h, and oceanic mixed layer Ekman drift U-OML. These results underscore the need for initializing coupled numerical models with realistic ocean states to correctly resolve the three-dimensional upwelling-downwelling responses and improve TC intensity forecasting.
引用
收藏
页码:1667 / 1689
页数:23
相关论文
共 77 条
  • [1] [Anonymous], WORLD WEATHER RESEAR
  • [2] A FIELD PERFORMANCE-TEST OF THE SIPPICAN DEEP AIRCRAFT-DEPLOYED EXPENDABLE BATHYTHERMOGRAPH
    BANE, JM
    SESSIONS, MH
    [J]. JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 1984, 89 (NC3): : 3615 - 3621
  • [3] Berg Robbie., 2013, Tropical Cyclone Report Hurricane Isaac - AL092012
  • [4] Air-sea exchange in hurricanes - Synthesis of observations from the coupled boundary layer air-sea transfer experiment
    Black, Peter G.
    D'Asaro, Eric A.
    Drennan, William M.
    French, Jeffrey R.
    Niiler, Pearn P.
    Sanford, Thomas B.
    Terrill, Eric J.
    Walsh, Edward J.
    Zhang, Jun A.
    [J]. BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY, 2007, 88 (03) : 357 - +
  • [5] CHANG SW, 1978, J PHYS OCEANOGR, V8, P468, DOI 10.1175/1520-0485(1978)008<0468:NSOTON>2.0.CO
  • [6] 2
  • [7] Cushman-Roisin B., 2011, Introduction to Geophysical Fluid Dynamics, V2nd
  • [8] Dinegar Boyd J., 1987, Journal of Atmospheric and Oceanic Technology, V4, P545, DOI 10.1175/1520-0426(1987)004<0545:IDATCE>2.0.CO
  • [9] 2
  • [10] On the limiting aerodynamic roughness of the ocean in very strong winds
    Donelan, MA
    Haus, BK
    Reul, N
    Plant, WJ
    Stiassnie, M
    Graber, HC
    Brown, OB
    Saltzman, ES
    [J]. GEOPHYSICAL RESEARCH LETTERS, 2004, 31 (18) : L183061 - 5