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Roger Pettipas - One of the best experts on this subject based on the ideXlab platform.
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Wind‐forcing of Volume Transport through Lancaster Sound
Journal of Geophysical Research, 2012Co-Authors: Ingrid Peterson, Simon Prinsenberg, James M. Hamilton, Roger PettipasAbstract:[1] Volume and freshwater Transport through Lancaster Sound are estimated from mooring measurements collected in eastern Barrow Strait for 13 years between 1998 and 2011. Estimates from 2006 to 2011 confirm the relationship between surface wind and Volume Transport derived from data collected between 1998 and 2006. Volume Transport through Barrow Strait along the Northwest Passage is significantly correlated with northeastward winds in the Beaufort Sea, parallel to the western coasts of the Canadian Arctic Archipelago, at monthly to interannual time scales. The location and wind direction for which there is maximum correlation are consistent with the flow being driven by a sea level difference between opposite ends of the Passage, and the difference being determined by setup caused by alongshore winds in the Beaufort Sea. Monthly alongshore wind anomalies account for 43% of the variance of the Transport anomalies (p 0.05). The annual cycles of the total Volume Transport and its part attributed to the Beaufort Sea wind both have peaks in the summer and are lowest in the autumn. Correlations of the Volume Transport anomaly with ice velocity anomalies are lower than with surface wind anomalies.
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wind forcing of Volume Transport through lancaster sound
Journal of Geophysical Research, 2012Co-Authors: Ingrid Peterson, James Hamilton, Simon Prinsenberg, Roger PettipasAbstract:[1] Volume and freshwater Transport through Lancaster Sound are estimated from mooring measurements collected in eastern Barrow Strait for 13 years between 1998 and 2011. Estimates from 2006 to 2011 confirm the relationship between surface wind and Volume Transport derived from data collected between 1998 and 2006. Volume Transport through Barrow Strait along the Northwest Passage is significantly correlated with northeastward winds in the Beaufort Sea, parallel to the western coasts of the Canadian Arctic Archipelago, at monthly to interannual time scales. The location and wind direction for which there is maximum correlation are consistent with the flow being driven by a sea level difference between opposite ends of the Passage, and the difference being determined by setup caused by alongshore winds in the Beaufort Sea. Monthly alongshore wind anomalies account for 43% of the variance of the Transport anomalies (p 0.05). The annual cycles of the total Volume Transport and its part attributed to the Beaufort Sea wind both have peaks in the summer and are lowest in the autumn. Correlations of the Volume Transport anomaly with ice velocity anomalies are lower than with surface wind anomalies.
Jong Hwan Yoon - One of the best experts on this subject based on the ideXlab platform.
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Seasonal Volume Transport variation in the Tsushima Warm Current through the Tsushima Straits from 10 years of ADCP observations
Journal of Oceanography, 2010Co-Authors: Ken-ichi Fukudome, Tetsutaro Takikawa, Jong Hwan Yoon, Alexander G. Ostrovskii, In Seong HanAbstract:The seasonal variation in the structure and Volume Transport of the Tsushima Warm Current through the Tsushima Straits is studied using the acoustic Doppler current profiler (ADCP) data obtained by the ferryboat Camellia between Hakata, Japan and Pusan, Korea from February 1997 to February 2007. A robust estimation method to eliminate the effects of aliasing and tidal signals more accurately leads to a significant increase in the Volume Transport in winter time compared to the previously reported one by Takikawa et al. (2005) who analyzed this ADCP dataset for the first 5.5 years. The 10 years average of Volume Transport through the Tsushima Straits is 2.65 Sv, and those through the channels east (CE) and west (CW) of the Tsushima Islands are 1.20 Sv and 1.45 Sv, respectively, which represent a 13% increase and an 8% decrease from those of Takikawa et al. (2005). The Transport through the CE increases rapidly from winter to spring and then decreases gradually as winter approaches. On the other hand, the Transport through the CW increases gradually from winter to autumn and then decreases rapidly as winter approaches. The Transport through the CE is larger than that of through the CW from February to April. The contribution of the Ekman Transport near the sea surface, which is not measured with the ADCP, to the seasonal Volume Transport variation across our ADCP section is not significant.
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variability of the Volume Transport through the korea tsushima strait as inferred from the shipborne acoustic doppler current profiler observations in 1997 2007
Oceanology, 2009Co-Authors: Alexander G. Ostrovskii, Ken-ichi Fukudome, Jong Hwan Yoon, Tetsutaro TakikawaAbstract:The 10-year series of observations of currents directed along the Korea/Tsushima Strait, which were measured with an acoustic Doppler current profiler aboard a ferry boat that cruised several times a week between the Hakata (Japan) and Pusan (South Korea) ports, is analyzed. Robust estimation methods are used to separate the tidal signal from the inhomogeneous series of the current data in the problem of the harmonic analysis. The MU2, NO1, PHI1, and J1 constituents have been estimated in addition to the MSF, MF, Q1, O1, P1, K1, N2, M2, S2, and K2 tidal harmonics detected previously. The annual variations in the amplitude of the M2 fundamental harmonic have also been taken into account. The current series cleared from the tidal signal has been processed in order to analyze the spatio-temporal variability of the Volume Transport through the Korea Strait. The normal annual velocity of the water inflow into the Japan Sea through the Korea Strait was 2.77 × 106 m3 s−1. The ratio of the flow rates in the eastern and western zones of the strait separated by the Tsushima Islands was 2/3. Considerable seasonal variations in the discharge are observed in the western strait zone: the flow rate annual maximum in October is 1.75 times as high as the minimum in February. An insignificant (not more than 0.1 × 106 m3 s−1 on average) southward flow can cross the eastern channel. Mesoscale vortices are generated in the lee of the Tsushima Islands when the northeastern current flows around them. The energy spectrum of the total nonseasonal flow rate through the Korea Strait has been constructed in the frequency range of 8–500 days. The spectrum has three significant maximums near periods of 10, 19, and 64 days. It has been indicated that this spectrum flattens at low frequencies (<0.1 day−1) in the vicinity of the formation of mesoscale vortices behind the Tsushima Islands.
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Effect of the along-strait wind on the Volume Transport through the Tsushima/Korea Strait in September
Journal of Oceanography, 2009Co-Authors: Jae Hong Moon, Jong Hwan Yoon, Naoki Hirose, Ig Chan PangAbstract:Recent investigation suggests that Volume Transport through the Tsushima/Korea Strait often has double peaks during the summer to autumn period with decreasing Transport in September. The satellite-observed wind changes from weak northwestward (across-strait) in summer to strong southwestward (along-strait) in early autumn (September) in the strait. Such a strong along-strait wind is related to tropical cyclones, which frequently pass through the East China Sea in September. The effect of the along-strait wind component on the Transport variation is examined using a three-dimensional numerical model. The simulated Volume Transport through the Tsushima/Korea Strait shows realistic seasonal and intra-seasonal variations. According to sensitivity experiments on local winds, the Transport variations in September are mainly generated by strong along-strait (southwestward) wind rather than weak across-strait wind. The strait Transport responds to the along-strait wind (southeastward), which produces a sea level increase along the Korean coast, resulting in the geostrophic balance across the strait. The Transport minimum through the Tsushima/Korea Strait in September can be determined by the combination of the across-strait geostrophic and along-strait ageostrophic balances.
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effect of the along strait wind on the Volume Transport through the tsushima korea strait in september
Journal of Oceanography, 2009Co-Authors: Jae Hong Moon, Jong Hwan Yoon, Naoki Hirose, Ig Chan PangAbstract:Recent investigation suggests that Volume Transport through the Tsushima/Korea Strait often has double peaks during the summer to autumn period with decreasing Transport in September. The satellite-observed wind changes from weak northwestward (across-strait) in summer to strong southwestward (along-strait) in early autumn (September) in the strait. Such a strong along-strait wind is related to tropical cyclones, which frequently pass through the East China Sea in September. The effect of the along-strait wind component on the Transport variation is examined using a three-dimensional numerical model. The simulated Volume Transport through the Tsushima/Korea Strait shows realistic seasonal and intra-seasonal variations. According to sensitivity experiments on local winds, the Transport variations in September are mainly generated by strong along-strait (southwestward) wind rather than weak across-strait wind. The strait Transport responds to the along-strait wind (southeastward), which produces a sea level increase along the Korean coast, resulting in the geostrophic balance across the strait. The Transport minimum through the Tsushima/Korea Strait in September can be determined by the combination of the across-strait geostrophic and along-strait ageostrophic balances.
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Volume Transport through the tsushima straits estimated from sea level difference
Journal of Oceanography, 2005Co-Authors: Tetsutaro Takikawa, Jong Hwan YoonAbstract:The relations between the Volume Transport and the sea level difference across the Tsushima Straits have been investigated using current data provided by ADCP mounted on the ferry Camellia, plying between Hakata and Pusan. Empirical formulas to deduce the Volume Transports using the sea level differences across the eastern and western channels are proposed, considering the seasonal variation of the vertical current structure. The interannual variation of Volume Transport through the Tsushima Straits for 37 years from 1965 to 2001 is estimated using the empirical formulas. The total Volume Transport through the Tsushima Straits, averaged for 37 years, is 2.60 Sv and those of the eastern and western channels are 1.13 Sv and 1.47 Sv, respectively. The total Volume Transport through the Tsushima Straits tends to decrease with a roughly 15 year variation until 1992, then begins to increase.
Sarah T. Gille - One of the best experts on this subject based on the ideXlab platform.
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Meridional Volume Transport in the South Pacific: Mean and SAM‐related variability
Journal of Geophysical Research, 2014Co-Authors: N. V. Zilberman, Dean Roemmich, Sarah T. GilleAbstract:The large increase in upper-ocean sampling during the past decade enables improved estimation of the mean meridional Volume Transport in the midlatitude South Pacific, and hence of the climatically important Meridional Overturning Circulation. Transport is computed using Argo float profile data for geostrophic shear and trajectory data for reference velocities at 1000 m. For the period 2004-2012, the mean geostrophic Transport across 32S is 20.6 ± 6.0 Sv in the top 2000 m of the ocean. From west to east, this includes the southward East Australian Current (23.3 ± 2.9 Sv), its northward recirculation (16.3 ± 3.6 Sv), the broad interior northward flow (18.4 ± 4.1 Sv), and the net northward flow (9.2 ± 2.2 Sv) in opposing currents in the eastern Pacific. The basin-integrated geostrophic Transport includes 7.3 ± 0.9 Sv of surface and thermocline waters, 4.9 ± 1.0 Sv of Subantarctic Mode Water, and 4.9 ± 1.4 Sv of Antarctic Intermediate Water. Interannual variability in Volume Transport across 32S in the South Pacific shows a Southern Annual Mode signature characterized by an increase during the positive phase of the Southern Annular Mode and a decrease during the negative phase. Maximum amplitudes in geostrophic Transport anomalies, seen in the East Australian Current and East Australian Current recirculation, are consistent with wind stress curl anomalies near the western boundary. Key Points Improved meridional Volume Transport in the South Pacific using Argo EAC Transport variability tied to the SAM © Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
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meridional Volume Transport in the south pacific mean and sam related variability
Journal of Geophysical Research, 2014Co-Authors: N. V. Zilberman, Dean Roemmich, Sarah T. GilleAbstract:The large increase in upper-ocean sampling during the past decade enables improved estimation of the mean meridional Volume Transport in the midlatitude South Pacific, and hence of the climatically important Meridional Overturning Circulation. Transport is computed using Argo float profile data for geostrophic shear and trajectory data for reference velocities at 1000 m. For the period 2004-2012, the mean geostrophic Transport across 32S is 20.6 ± 6.0 Sv in the top 2000 m of the ocean. From west to east, this includes the southward East Australian Current (23.3 ± 2.9 Sv), its northward recirculation (16.3 ± 3.6 Sv), the broad interior northward flow (18.4 ± 4.1 Sv), and the net northward flow (9.2 ± 2.2 Sv) in opposing currents in the eastern Pacific. The basin-integrated geostrophic Transport includes 7.3 ± 0.9 Sv of surface and thermocline waters, 4.9 ± 1.0 Sv of Subantarctic Mode Water, and 4.9 ± 1.4 Sv of Antarctic Intermediate Water. Interannual variability in Volume Transport across 32S in the South Pacific shows a Southern Annual Mode signature characterized by an increase during the positive phase of the Southern Annular Mode and a decrease during the negative phase. Maximum amplitudes in geostrophic Transport anomalies, seen in the East Australian Current and East Australian Current recirculation, are consistent with wind stress curl anomalies near the western boundary. Key Points Improved meridional Volume Transport in the South Pacific using Argo EAC Transport variability tied to the SAM © Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
Ingrid Peterson - One of the best experts on this subject based on the ideXlab platform.
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Wind‐forcing of Volume Transport through Lancaster Sound
Journal of Geophysical Research, 2012Co-Authors: Ingrid Peterson, Simon Prinsenberg, James M. Hamilton, Roger PettipasAbstract:[1] Volume and freshwater Transport through Lancaster Sound are estimated from mooring measurements collected in eastern Barrow Strait for 13 years between 1998 and 2011. Estimates from 2006 to 2011 confirm the relationship between surface wind and Volume Transport derived from data collected between 1998 and 2006. Volume Transport through Barrow Strait along the Northwest Passage is significantly correlated with northeastward winds in the Beaufort Sea, parallel to the western coasts of the Canadian Arctic Archipelago, at monthly to interannual time scales. The location and wind direction for which there is maximum correlation are consistent with the flow being driven by a sea level difference between opposite ends of the Passage, and the difference being determined by setup caused by alongshore winds in the Beaufort Sea. Monthly alongshore wind anomalies account for 43% of the variance of the Transport anomalies (p 0.05). The annual cycles of the total Volume Transport and its part attributed to the Beaufort Sea wind both have peaks in the summer and are lowest in the autumn. Correlations of the Volume Transport anomaly with ice velocity anomalies are lower than with surface wind anomalies.
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wind forcing of Volume Transport through lancaster sound
Journal of Geophysical Research, 2012Co-Authors: Ingrid Peterson, James Hamilton, Simon Prinsenberg, Roger PettipasAbstract:[1] Volume and freshwater Transport through Lancaster Sound are estimated from mooring measurements collected in eastern Barrow Strait for 13 years between 1998 and 2011. Estimates from 2006 to 2011 confirm the relationship between surface wind and Volume Transport derived from data collected between 1998 and 2006. Volume Transport through Barrow Strait along the Northwest Passage is significantly correlated with northeastward winds in the Beaufort Sea, parallel to the western coasts of the Canadian Arctic Archipelago, at monthly to interannual time scales. The location and wind direction for which there is maximum correlation are consistent with the flow being driven by a sea level difference between opposite ends of the Passage, and the difference being determined by setup caused by alongshore winds in the Beaufort Sea. Monthly alongshore wind anomalies account for 43% of the variance of the Transport anomalies (p 0.05). The annual cycles of the total Volume Transport and its part attributed to the Beaufort Sea wind both have peaks in the summer and are lowest in the autumn. Correlations of the Volume Transport anomaly with ice velocity anomalies are lower than with surface wind anomalies.
Christine Provost - One of the best experts on this subject based on the ideXlab platform.
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Twenty-five years of Mercator ocean reanalysis GLORYS12 at Drake Passage: velocity assessment and total Volume Transport
Advances in Space Research, 2019Co-Authors: Camila Artana, Ramiro Ferrari, Clément Bricaud, Jean-michel Lellouche, Gilles Garric, Nathalie Sennéchael, Jae Hak Lee, Young-hyang Park, Christine ProvostAbstract:Abstract Velocities in Drake Passage from the 25-year GLORYS12 Mercator Ocean reanalysis were compared with satellite altimetry-derived surface velocities and independent in-situ velocity measurements from the DRAKE (2006–2009) and cDrake (2007–2011) experiments. GLORYS12 assimilates satellite along-track sea level anomalies and, as expected, model velocities are in rather good agreement with gridded altimetry derived velocities (r ~ 0.5, above 99% confidence level). GLORYS12 velocities also compared well with the current-meter data from the DRAKE (in the water column) and cDrake (50 m above seafloor) experiments in terms of means and standard deviations; most correlations between the reanalysis and directly measured velocity time series were significant (r ~ 0.5 for DRAKE and r ~ 0.4 for cDrake, above 99% confidence level). We used the GLORYS12 reanalysis to examine the Antarctic Circumpolar Current (ACC) total Volume Transport across three sections in Drake Passage. The 25 years of the ACC total Volume Transport has a mean of 155 ± 3 Sv and a standard deviation of 6.7 Sv. Annual mean values span over a range of 12 Sv. The spectrum of the GLORYS12 total Transport time series shows energy peaks (above 95% confidence level) at the intraseasonal, semi-annual and annual periods and no significant low-frequency variations (beyond 2 years) or trend, in agreement with previous studies. This first assessment of GLORYS12 velocities in Drake Passage is very encouraging for monitoring the regional variability of the ACC.
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Variations in the Malvinas Current Volume Transport since October 1992
Journal of Geophysical Research, 2009Co-Authors: Aurélie Spadone, Christine ProvostAbstract:[1] We present a set of new current meter measurements collected to monitor the Malvinas Current (MC) near its merger with the Brazil Current at 40–41°S from December 2001 to February 2003 below a Jason-1 altimeter track. These measurements are compared to former measurements obtained 8 years earlier at the same location; they also provide new information on the core of the MC on the continental slope above the 1000-m isobath where a mooring had been previously lost. There, most of the velocity variation is along-isobath (80% of the variance) and shows a significant annual cycle. The two data sets provide coherent means and statistical parameters on the vertical structure of the flow. A 14-year-long time series of MC Volume Transport is derived using satellite altimetry. The good correlation between the altimetry-derived Transport and the Transport estimated from the current meter data persists in time (over 0.7 for each measurement period). A spectacular shift in the spectral composition of Transport variations was observed: from 1992 until the end of 1997 Transport variations occurred at rather short periods (50–90 days and to some degree around 180 days) whereas, after year 2000, longer periods including a seasonal cycle predominated. Altimetry-derived anomalies of surface geostrophic velocities along the core of the MC show a similar shift in spectral composition suggesting a remote-forcing origin.
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Volume Transport of the Malvinas Current: Can the flow be monitored by TOPEX/POSEIDON?
Journal of Geophysical Research, 1999Co-Authors: Frédéric Vivier, Christine ProvostAbstract:Current meter measurements were collected between 40° and 41°S in the Malvinas (Falkland) Current from December 1993 to June 1995. Owing to the premature failure of a mooring, a reliable Volume Transport time series could only be calculated for 254 days, leading to a mean Transport of about 41.5 Sv with a standard deviation of 12.2 Sv. This time series is tentatively extended to 386 days. It is also shown that the TOPEX/POSEIDON altimeter, combined with the statistical information on the vertical structure of the current provided by the current meters, can be used to sensitively monitor the flow. A 3-year-long time series of Transport is derived, which is well correlated (0.8) to the Transport estimated from current meters, including about 60% of the variance of the flow at periods beyond 20 days; this series makes it possible to consider a relatively broad spectral range. Dominant periods are 50–80 days and close to 180 days. Interannual variations are large. Comparatively, little energy is found at the annual period, suggesting that the Malvinas Current has only little impact on the annual migrations of the confluence. The predominance of a semiannual cycle is compatible with a remote forcing of the flow suggested by previous numerical studies.
