Records
Links
Author Ajayi, A. ; Le Sommer, J. ; Chassignet, E. ; Molines, J.-M. ; Xu, X. ; Albert, A. ; Cosme, E.
Title Spatial and Temporal Variability of the North Atlantic Eddy Field From Two Kilometric-Resolution Ocean Models Type $loc['typeJournal Article']
Year 2020 Publication Journal of Geophysical Research: Oceans Abbreviated Journal J. Geophys. Res. Oceans
Volume 125
Issue 5
Pages
Keywords submesoscales ; fine‐ ; scales ; enstrophy ; eddies ; SWOT
Abstract Ocean circulation is dominated by turbulent geostrophic eddy fields with typical scales ranging from 10 to 300 km. At mesoscales (>50 km), the size of eddy structures varies regionally following the Rossby radius of deformation. The variability of the scale of smaller eddies is not well known due to the limitations in existing numerical simulations and satellite capability. Nevertheless, it is well established that oceanic flows (<50 km) generally exhibit strong seasonality. In this study, we present a basin‐scale analysis of coherent structures down to 10 km in the North Atlantic Ocean using two submesoscale‐permitting ocean models, a NEMO‐based North Atlantic simulation with a horizontal resolution of 1/60 (NATL60) and an HYCOM‐based Atlantic simulation with a horizontal resolution of 1/50 (HYCOM50). We investigate the spatial and temporal variability of the scale of eddy structures with a particular focus on eddies with scales of 10 to 100 km, and examine the impact of the seasonality of submesoscale energy on the seasonality and distribution of coherent structures in the North Atlantic. Our results show an overall good agreement between the two models in terms of surface wave number spectra and seasonal variability. The key findings of the paper are that (i) the mean size of ocean eddies show strong seasonality; (ii) this seasonality is associated with an increased population of submesoscale eddies (10�50 km) in winter; and (iii) the net release of available potential energy associated with mixed layer instability is responsible for the emergence of the increased population of submesoscale eddies in wintertime.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2169-9275
ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ user @
Serial 1104
Permanent link to this record
Author Zhao, X. ; Zhou, C. ; Xu, X. ; Ye, R. ; Tian, J. ; Zhao, W.
Title Deep Circulation in the South China Sea Simulated in a Regional Model Type $loc['typeJournal Article']
Year 2019 Publication Ocean Sci. Discuss Abbreviated Journal Ocean Sci. Discuss
Volume Issue Pages
Keywords Sea Marine, Oceanography/CIMST, PacificOcean, continuous current-meter, deep circulation, deep western boundary
Abstract The South China Sea (SCS) is the largest marginal sea in the northwest Pacific Ocean. In this study, deep circulation in the SCS is investigated using results from eddy-resolving, regional simulations using the Hybrid Coordinate Ocean Model (HYCOM) verified by continuous current-meter observations. Analysis of these results provides a detailed spatial structure and temporal variability of the deep circulation in the SCS. The major features of the SCS deep circulation are a basin-scale cyclonic gyre and a concentrated deep western boundary current (DWBC). Transport of the DWBC is ∼ 2 Sv at 16.5° N with a width of ∼53 km. Flowing southwestward, the narrow DWBC becomes weaker with a wider range. The model results reveal the existence of 80- to 120-day oscillation in the deep northeastern circulation and the DWBC, which are also the areas with elevated eddy kinetic energy. This intraseasonal oscillation propagates northwestward with a velocity amplitude of ∼ 1.0 to 1.5 cm s-1. The distribution of mixing parameters in the deep SCS plays a role in both spatial structure and volume transport of the deep circulation. Compared with the northern shelf of the SCS with the Luzon Strait, deep circulation in the SCS is more sensitive to the large vertical mixing parameters of the Zhongsha Island Chain area.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ user @
Serial 1013
Permanent link to this record
Author Xu, X. ; Chassignet, E.P. ; Firing, Y.L. ; Donohue, K.
Title Antarctic Circumpolar Current transport through Drake Passage: What can we learn from comparing high-resolution model results to observations? Type $loc['typeJournal Article']
Year 2020 Publication Journal of Geophysical Research: Oceans Abbreviated Journal J. Geophys. Res. Oceans
Volume 125
Issue 7
Pages
Keywords
Abstract Uncertainty exists in the time‐mean total transport of the Antarctic Circumpolar Current (ACC), the world�s strongest ocean current. The two most recent observational programs in Drake Passage, DRAKE and cDrake, yielded transports of 141 and 173.3 Sv, respectively. In this paper, we use a realistic 1/12° global ocean simulation to interpret these observational estimates and reconcile their differences. We first show that the modeled ACC transport in the upper 1000 m is in excellent agreement with repeat shipboard acoustic Doppler current profiler (SADCP) transects and that the exponentially decaying transport profile in the model is consistent with the profile derived from repeat hydrographic data. By further comparing the model results to the cDrake and DRAKE observations, we argue that the modeled 157.3 Sv transport, i.e. approximately the average of the cDrake and DRAKE estimates, is actually representative of the time‐mean ACC transport through the Drake Passage. The cDrake experiment overestimated the barotropic contribution in part because the array undersampled the deep recirculation southwest of the Shackleton Fracture Zone, whereas the surface geostrophic currents used in the DRAKE estimate yielded a weaker near‐surface transport than implied by the SADCP data. We also find that the modeled baroclinic and barotropic transports are not correlated, thus monitoring either baroclinic or barotropic transport alone may be insufficient to assess the temporal variability of the total ACC transport.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Medium
Area Expedition Conference
Funding Approved $loc['no']
Call Number COAPS @ user @
Serial 1107
Permanent link to this record
