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Barry Ma

Senior Oceanographer

Email

barry@apl.washington.edu

Phone

206-221-4720

Department Affiliation

Ocean Physics

Education

B.S., 1988

M.S. Physical Oceanography, US Naval Postgraduate School, 1998

Ph.D. Oceanography, University of Washington, 2004

Publications

2000-present and while at APL-UW

Downstream evolution of the Kuroshio's time-varying transport and velocity structure

Andres, M., V. Mensah, S. Jan, M.-H. Chang, Y.-J. Yang, C.M. Lee, B. Ma, and T.B. Sanford, "Downstream evolution of the Kuroshio's time-varying transport and velocity structure," J. Geophys. Res., 122, 3519-3542, doi:10.1002/2016JC012519, 2017.

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1 May 2017

Observations from two companion field programs—Origins of the Kuroshio and Mindanao Current (OKMC) and Observations of Kuroshio Transport Variability (OKTV)—are used here to examine the Kuroshio's temporal and spatial evolution. Kuroshio strength and velocity structure were measured between June 2012 and November 2014 with pressure-sensor equipped inverted echo sounders (PIESs) and upward-looking acoustic Doppler current profilers (ADCPs) deployed across the current northeast of Luzon, Philippines, and east of Taiwan with an 8 month overlap in the two arrays' deployment periods. The time-mean net (i.e., integrated from the surface to the bottom) absolute transport increases downstream from 7.3 Sv (±4.4 Sv standard error) northeast of Luzon to 13.7 Sv (±3.6 Sv) east of Taiwan. The observed downstream increase is consistent with the return flow predicted by the simple Sverdrup relation and the mean wind stress curl field over the North Pacific (despite the complicated bathymetry and gaps along the North Pacific western boundary). Northeast of Luzon, the Kuroshio—bounded by the 0 m s–1 isotach—is shallower than 750 dbar, while east of Taiwan areas of positive flow reach to the seafloor (3000 m). Both arrays indicate a deep counterflow beneath the poleward-flowing Kuroshio (–10.3 ± 2.3 Sv by Luzon and –12.5 ± 1.2 Sv east of Taiwan). Time-varying transports and velocities indicate the strong influence at both sections of westward propagating eddies from the ocean interior. Topography associated with the ridges east of Taiwan also influences the mean and time-varying velocity structure there.

Ekman circulation in the Arctic Ocean: Beyond the Beaufort Gyre

Ma, B., M. Steele, and C.M. Lee, "Ekman circulation in the Arctic Ocean: Beyond the Beaufort Gyre," J. Geophys. Res., 122, 3358-3374, doi:10.1002/2016JC012624, 2017.

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1 Apr 2017

Data derived from satellite-based observations, with buoy-based observations and assimilations, are used to calculate ocean Ekman layer transport and evaluate long-term trends in the Arctic Ocean over the period 1979–2014. The 36 year mean of upwelling (downwelling) is 3.7 ± 2.0 (–4.0 ± 2.2) Sv for the entire Arctic Basin, with ~0.3 Sv net downwelling contributed mostly by the Canadian region. With regard to long-term trends, the annual mean upwelling (downwelling) over the entire Arctic Basin is increasing at a linear rate of 0.92 (–0.98) Sv/decade. The Canada/Alaska coasts and Beaufort and Laptev Seas are regions of greatest Ekman transport intensification. The central Arctic Ocean and Lincoln Sea also have an increasing trend in transport. The Canadian and Eurasian regions each account for about half the total vertical Ekman variations in the Arctic Basin.

The surface mixed layer heat budget from mooring observations in the central Indian Ocean during Madden–Julian Oscillation events

Chi, N.-H., R.-C. Lien, E.A. D'Asaro, and B.B. Ma, "The surface mixed layer heat budget from mooring observations in the central Indian Ocean during Madden–Julian Oscillation events," J. Geophys. Res., 119, 4638-4652, doi:10.1002/2014JC010192, 2014.

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1 Jul 2014

The oceanic surface mixed layer heat budget in the central equatorial Indian Ocean is calculated from observations at two mooring sites (0°S 79°E and 1.5°S 79°E) during three active and calm phases of Madden–Julian Oscillation (MJO) events between September 2011 and January 2012. At both mooring locations, the surface mixed layer is generally heated during MJO calm phases. During MJO active phases at both mooring locations, the surface mixed layer is always cooled by the net surface heat flux and also sometimes by the turbulent heat flux at the bottom of the surface mixed layer. The turbulent heat flux at the bottom of the surface mixed layer, however, varies greatly among different MJO active phases and between the two mooring locations. A barrier layer exerts control on the turbulent heat flux at the base of the surface mixed layer; we quantify this barrier layer strength by a "barrier layer potential energy," which depends on the thickness of the barrier layer, the thickness of the surface mixed layer, and the density stratification across the isothermal layer. During one observed MJO active phase, a strong turbulent heat flux into the mixed layer was diagnosed, despite the presence of a 10–20 m thick barrier layer. This was due to the strong shear across the barrier layer driven by the westerly winds, which provided sufficient available kinetic energy to erode the barrier layer. To better simulate and predict net surface heat fluxes and the MJO, models must estimate the oceanic barrier layer potential energy, background shear, stratification, and surface forcing accurately.

More Publications

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
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