Search Results

You are looking at 11 - 20 of 807 items for :

  • Journal of Physical Oceanography x
  • All content x
Clear All
Daniel L. Rudnick, W. Brechner Owens, T. M. Shaun Johnston, Kristopher B. Karnauskas, Julie Jakoboski, and Robert E. Todd

height of the El Niño event, temperature anomalies approached 2.5°C in the vicinity of the Galápagos Islands and the site of ROGER observations. As is the case in much of the tropics, the El Niño signal is much larger than the annual cycle, which has an amplitude of less than 1°C averaged over the upper 300 m of this region ( Gasparin and Roemmich 2017 ). The El Niño waned in 2016, with a very weak La Niña following. Fig . 9. (a) Temperature anomaly in the upper 300 m and (b) eastward 10-m wind

Restricted access
Kenneth G. Hughes, James N. Moum, and Emily L. Shroyer

1. Introduction Diurnal warm layers (DWLs) form when strong solar radiation and weak-to-moderate winds allow near-surface stratification to develop. In the tropics DWLs appear around 0800 local time (LT), which is 1–2 h after sunrise, as the surface heat flux changes from net ocean cooling to net warming ( Martin 1985 ; Fairall et al. 1996 ; Moulin et al. 2018 ). Heat and momentum trapped in this stratified layer cause sea surface temperature (SST) anomalies of O (0.1–1°C) and near

Restricted access
Tangdong Qu, Shan Gao, Ichiro Fukumori, Rana A. Fine, and Eric J. Lindstrom

Pacific ( Stroup 1969 ; Tsuchiya 1981 ). This water mass lies in a density range between σ θ = 26.23 and 26.65 kg m −3 at temperatures near 13°C at 105°W and tends to get lighter toward the eastern boundary ( Johnson et al. 2002 ). The cool temperature and high salinity of this water mass indicate a source region well outside the tropics (e.g., Tsuchiya 1981 ; Toggweiler et al. 1991 ; Bingham and Lukas 1995 ). Based on a model simulation, Qu et al. (2009) recently demonstrated that the 13°C

Full access
Kaushik Srinivasan, James C. McWilliams, Lionel Renault, Hristina G. Hristova, Jeroen Molemaker, and William S. Kessler

–anticyclone symmetry ( ζ ↔ − ζ ) that is approximately validated in observed ( Chelton et al. 2011 ) and modeled ( Tulloch et al. 2011 ) analyses of mesoscale eddies. QG mesoscale eddies also have a relatively weak vertical velocity w , solely because of the deflection of isopycnals over the spatial scale of the pycnocline baroclinic deformation radius R d (≈50 km in the midlatitudes and even larger in the tropics). Recent studies ( Callies et al. 2015 ; Chavanne and Klein 2016 ) using mixed layer QG models

Full access
S. Cravatte, Elodie Kestenare, Frédéric Marin, Pierre Dutrieux, and Eric Firing

. In the tropics and near the equator, a theory to explain these systems of jets as a whole is still lacking. At present, the available theories address the formation of only specific parts of these systems of jets, focusing either on the near-equatorial circulation (Tsuchiya jets, deep jets at the equator and intermediate currents between 3°S and 3°N) or on extraequatorial intermediate currents (poleward of ~9°N). These theories are briefly presented; the purpose is not to describe them

Full access
Kenneth G. Hughes, James N. Moum, and Emily L. Shroyer

constant, U cr changes by only 0.3 m s −1 for latitudes between 1° and 60° and changes by only 0.5 m s −1 for choices of t between 3 and 7 h. A detailed examination of the sensitivity of Eq. (10) in Fig. 12 shows that within a wide range of plausible input values, U cr is within ±30% of 2.0 m s −1 . Given this limited sensitivity, while also recognizing that variability exists, we consider the 2 m s −1 threshold as a convenient rule of thumb, especially for the tropics, where day length

Free access
Martín S. Hoecker-Martínez, William D. Smyth, and Eric D. Skyllingstad

tropics . J. Atmos. Sci. , 34 , 901 – 910 , doi: 10.1175/1520-0469(1977)034<0901:VIGWAL>2.0.CO;2 . Chen , G. , B. Chapron , R. Ezraty , and D. Vandemark , 2002 : A global view of swell and wind sea climate in the ocean by satellite altimeter and scatterometer . J. Atmos. Oceanic Technol. , 19 , 1849 – 1859 , doi: 10.1175/1520-0426(2002)019<1849:AGVOSA>2.0.CO;2 . Chi , N.-H. , R.-C. Lien , E. A. D’Asaro , and B. B. Ma , 2014 : The surface mixed layer heat budget from

Full access
Yuanlong Li, Weiqing Han, Toshiaki Shinoda, Chunzai Wang, M. Ravichandran, and Jih-Wang Wang

; Xavier 2012 ; Hung et al. 2013 ). In the tropics, the ocean affects the atmosphere mainly through the variability of sea surface temperature (SST). Recent studies demonstrated that the upper-ocean dynamics and relevant SST variability in the tropical Indian Ocean act as a potential trigger for some of the MJO events ( Webber et al. 2010 , 2012a , b ). Therefore, investigating the intraseasonal SST variability in the tropical Indian Ocean and its driving mechanism is a key step toward a better

Full access
Milena Veneziani, Annalisa Griffa, Zulema Garraffo, and Jean A. Mensa

the barrier layer in the surface layer of the tropics. J. Geophys. Res., 97 (C5), 7305–7316. Sprintall , J. , and D. Roemmich , 1999 : Characterizing the structure of the surface layer in the Pacific Ocean. J. Geophys. Res., 104 (C10), 23 297–23 311. Stramma , L. , and F. Schott , 1999 : The mean flow field of the tropical Atlantic Ocean. Deep-Sea Res. II, 46 (1–2), 279–303 , doi:10.1016/S0967-0645(98)00109-X . Stramma , L. , M. Rhein , P. Brandt , M. Dengler

Full access
Marlos Goes, David P. Marshall, and Ilana Wainer

Abstract

The variability of the meridional overturning circulation (MOC) in the upper tropical Atlantic basin is investigated using a reduced-gravity model in a simplified domain. Four sets of idealized numerical experiments are performed: (i) switch-on of the MOC until a fixed value when a constant northward flow is applied along the western boundary; (ii) MOC with a variable flow; (iii) MOC in a quasi-steady flow; and (iv) shutdown of the MOC in the Northern Hemisphere. Results from experiments (i) show that eddies are generated at the equatorial region by shear instability and detached northward; eddies are responsible for an enhancement of the mean flow and the variability of the MOC. Results from experiments (ii) show a transitional behavior of the MOC related to the eddy generation in interannual–decadal time scales as the Reynolds number varies due to the variations in the MOC. In experiments (iii), a critical Reynolds number Rec around 30 is found, above which eddies are generated. Experiments (iv) demonstrate that even after the collapse of MOC in the Northern Hemisphere, eddies can still be generated and carry energy across the equator into the Northern Hemisphere; these eddies act to attenuate the impact of the MOC shutdown on short time scales. The results described here may be particularly pertinent to ocean general circulation models in which the Reynolds number lies close to the bifurcation point separating the laminar and turbulent regimes.

Full access