Extra-anatomical bypass formation and exclusion of thoracic aortic aneurysms by "paired clamp method": the development of hind leg paralysis, the thrombus formation and the pressure ratio between the excluded cavity and the aorta.

The extra-anatomical bypass formation and the exclusion of thoracic aortic aneurysms by the &#34;paired clamp method&#34; applied to the thoracic aorta of mongrel dogs, and the development of hind leg paralysis was studied experimentally in relation to the ratio between the mean excluded cavity pressure and the mean aortic pressure ratio (EA-ratio). The relationship between thrombus formation in the excluded cavity and the EA-ratio was also studied. Animals were divided into 4 groups: Group 1 underwent the cross-clamping of the descending thoracic aorta for 8 min; Group 2 underwent exclusion of the entire thoracic aorta under permanent bypass; Group 3 underwent ligation of 2/3 of the proximal intercostal arteries which branched from the excluded thoracic aorta; and Group 4 underwent division of the excluded thoracic aorta into 3 parts by ligation. No animals in group 1 developed paralysis. When EA-ratios were higher than 0.48, animals in groups 2 and 3 were not paralyzed, whereas all but 1 animals with EA-ratios lower than or equal to 0.48 were paralyzed. There was statistically significant difference between the EA-ratio of the non-paralyzed animals and that of the paralyzed animals in groups 2 and 3. Four out of 5 animals in group 4 were paralyzed. However, there was no statistically significant difference between the EA-ratio in these 4 paralyzed animals and that in the non-paralyzed animals in groups 2 and 3. When the EA-ratio was lower than or equal to 0.59, all but 1 excluded cavities of groups 2 and 3 animals were fully thrombosed 7 or 8 days after the operation. None of these animals showed the aggravation of the paralysis during the observation period and, conversely, the paralysis of almost all animals was ameliorated. These results suggested that the EA-ratio is useful in predicting the development of paralysis and thrombus formation in the excluded cavity after the operation of thoracic aortic aneurysms by the &#34;paired clamp method&#34;.</p

Oceanic Boundary Currents

Measurements of oceanic boundary currents for integral quantities such as heat and freshwater transports are very important for studying their long-term impacts on the global climate. There are a variety of boundary currents, including surface, intermediate and deep boundary currents on both the western and eastern sides of ocean basins. The dynamics and physics of these boundary currents are different, as are the ways of monitoring them. Here, we choose to explore the strategies adopted for observing four representative boundary current systems which have been the subject of detailed studies in recent years: the Kuroshio; the East Australian Current; the Indonesian Throughflow; and the low-latitude boundary current System of the Atlantic. The transport of the Kuroshio south of Japan has been monitored using satellite altimeter data in conjunction with an empirical relation between the transport and sea surface height difference across the stream. Monitoring the transport of the East Australian Current has been achieved by repeated high-resolution expendable bathythermograph (XBT) and/or conductivity-temperature-depth profiler transects maintained at several locations, supplemented with satellite altimeter data. Repeated XBT transects have also been used to monitor transport of the Indonesian Throughflow, in association with current meter and other instrumental estimations of transport through a few major throughflow straits. Finally, the complicated flow field of the low-latitude boundary current system of the Atlantic has been revealed using neutrally buoyant floats, moored current meters and hydrographic observations. The survey will be continued using further advanced observation technologies

The Kuroshio Region off Southwest Japan ASUKA 1993-95 Inverted Echo Sounder Data Report

In order to study the time-varying volume and heat transports of the Kuroshio off southwest Japan, a large number of scientists from Japan and a small number from the U.S.A. formed a group called ASUKA. This group carried out a coordinated investigation which was concentrated in time on the years 1993-95, and in space on a 1,000 km segment of a TOPEX/POSEIDON suborbital track running south-southeast from western Shikoku. This report describes the techniques used to process data collected by ten inverted echo sounders (IES) on this 1,000 km line off Japan, as part of the ASUKA study. The University of Rhode Island (URI) was responsible for all the IES\u27s except IES5 and IES8 which were from the Hydrographic Department of the Japanese Maritime Safety Agency (MSA/HD). The URI IES\u27s were deployed from the Training Vessel Keiten-maru in October 1993 and recovered from the same vessel in November 1995. The MSA/HD IES\u27s were deployed from the Survey Vessel Shoyo in July 1993. IES8 was recovered by Shoyo in May 1994, but unfortunately IES5 was not recovered

Sea surface slope as a proxy for Agulhas Current strength

The linear relation between the strength of the Agulhas Current at nominal latitude 34°S and the gradient in sea level height anomaly across the current is investigated in a 1/10° resolution regional numerical ocean model. Our results show that the strength of the current can be estimated with reasonable accuracy using altimeter data, once it has been calibrated using in-situ transport measurements. Three years of transport measurements provide a calibration with worst-case correlation R = 0.78. In that case the errors in proxy transport have a standard deviation of 9.8 Sv, compared to a 20.2 Sv standard deviation of the transport time series itself. From these results we conclude that the design of the Agulhas Current Timeseries (ACT) experiment, a three-year deployment of moorings across the Agulhas Current and along a TOPEX/Jason altimeter ground track, will likely produce a good quality multi-decadal time series of Agulhas Current strength

Mean transport and seasonal cycle of the Kuroshio east of Taiwan with comparison to the Florida Current

Moored observations of Kuroshio current structure and transport variability were made across the channel between northeast Taiwan and the Ryukyu Islands at 24 degreesN from September 19, 1994, to May 27, 1996. This was a cooperative, effort between the United States and Taiwan. The moored array was designated PCM-1, for the World Ocean Circulation Experiment (WOCE) transport resolving array. The dominant current and transport variability occurred on 100-day timescales and is shown by Zhang et al. [2001] to be caused by warm mesoscale eddys merging with the Kuroshio south of the array causing offshore meandering and flow splitting around the Ryukyu Islands. An annual transport cycle could not be resolved from our 20-month moored record because of abasing from the 100-day period events. Sea level difference data were used to extend the transport time series to 7 years giving a variation in the range of the annual transport cycle of 4-10 Sv, with a mean range closer to 4 Sv. The seasonal maximum of 24 Sv occurred in the summer and the seasonal minimum of 20 Sv occurred in the fall. A weaker secondary maximum also occurred in the winter. The cycle of Kuroshio transport appears to result from a combination of local along-channel wind forcing and Sverdrup forcing over the Philippine Sea. Our estimate of the mean transport of the Kuroshio at the entrance to the East China Sea from the moored array is 21.5 +/- 2.5 Sv. The mean transpacific balance of meridional flows forced by winds and thermohaline processes at this latitude requires an additional mean northward flow of 12 Sv with an annual cycle of +/-8 Sv along the eastern boundary of the Ryukyu Islands. The mean transport and annual cycle of the Kuroshio were found to be in reasonable agreement with basin-scale wind-forced models. Remarkable similarities are shown to exist between the mean western boundary currents and their seasonal cycles in the Atlantic (Florida Current and Antilles Current) and Pacific (Kuroshio and boundary current east of Ryukyu Island chain) at the same latitude. However, detailed comparison shows that the mean Kuroshio is weaker and more surface intensified than the mean Florida Current, while the Kuroshio-transport variability is significantly larger

A new method for estimating the turbulent heat flux at the bottom of the daily mixed layer

A new method is presented for estimating the vertical turbulent heat flux at the bottom of the daily mixed layer from the temperature data in the mixed layer and net solar irradiance data at the sea surface. We assume that fluctuations in the divergence of advective heat flux have longer than daily time scales. The method is applied to data from the eastern tropical Pacific, where the daily cycle in the temperature field is confined to the upper 10-25 m. The night-to-day difference of the turbulent heat flux calculated from the data obtained during nine daily cycles in November 1984 agrees well on average with the same quantity estimated from microstructure observations. The night-to-day difference of the turbulent heat flux, estimated at several mooring stations near the equator (an average over 100 to 300 daily cycles), varies from 120 to 220 W/m² with larger values on the equator. Equatorial turbulence measurements show that the turbulent heat flux is much larger during nighttime than daytime. Therefore the present estimates give approximately the nighttime average, which is the major part of the turbulent heat flux. From the daytime heat budget we obtain divergence of the low-frequency horizontal heat advection at 1°30’S, 140°W; it is governed by equatorial mesoscale fluctuations having a predominant period of 15-20 days

The WOCE–era 3–D Pacific Ocean circulation and heat budget

Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Progress In Oceanography 82 (2009): 281-325, doi:10.1016/j.pocean.2009.08.002.To address questions concerning the intensity and spatial structure of the 3–dimensional circulation within the Pacific Ocean and the associated advective and diffusive property flux divergences, data from approximately 3000 high–quality hydrographic stations collected on 40 zonal and meridional cruises have been merged into a physically consistent model. The majority of the stations were occupied as part of the World Ocean Circulation Experiment (WOCE), which took place in the 1990s. These data are supplemented by a few pre–WOCE surveys of similar quality, and time–averaged direct–velocity and historical hydrographic measurements about the equator. An inverse box model formalism is employed to estimate the absolute along–isopycnal velocity field, the magnitude and spatial distribution of the associated diapycnal flow and the corresponding diapycnal advective and diffusive property flux divergences. The resulting large–scale WOCE Pacific circulation can be described as two shallow overturning cells at mid– to low latitudes, one in each hemisphere, and a single deep cell which brings abyssal waters from the Southern Ocean into the Pacific where they upwell across isopycnals and are returned south as deep waters. Upwelling is seen to occur throughout most of the basin with generally larger dianeutral transport and greater mixing occurring at depth. The derived pattern of ocean heat transport divergence is compared to published results based on air–sea flux estimates. The synthesis suggests a strongly east/west oriented pattern of air–sea heat flux with heat loss to the atmosphere throughout most of the western basins, and a gain of heat throughout the tropics extending poleward through the eastern basins. The calculated meridional heat transport agrees well with previous hydrographic estimates. Consistent with many of the climatologies at a variety of latitudes as well, our meridional heat transport estimates tend toward lower values in both hemispheres.This work was funded by National Science Foundation grants OCE–9710102, OCE– 9712209 and OCE–0079383, and also benefited from work on closely related projects funded by NSF grants OCE–0223421 and OCE–0623261, and NOAA grant NA17RJ1223 funded through CICOR. For G.C.J. NASA funding came under Order W–19,314

Fourier Filtering in a Barotropic Polar Ocean Model

A Fourier filtering is examined in a polar ocean model based on the vorticity equation. A circular basin centered at the North Pole is considered. Flows are driven by an inflow and an outflow prescribed at the circumference. Two peninsulas are provided for examination of the filtering effect. In a slip boundary case, longitudinal distribution of the predicted vorticity is expanded in sine series and high wavenumber components are eliminated. The solution obtained with the filtering agrees well with that obtained without filterings. In a viscous boundary case, the vorticity is expanded in cosine series and high wavenumber components are eliminated. The filtering does not affect the general flow pattern, although it slightly affects the local vorticity field near irregular coastal boundaries