Zonal Volume Research Articles

Upper ocean variability on the equator in the Pacific at 170°W

The monitoring of upper ocean velocity, temperature, and surface winds at 0°, 170°W was initiated in May 1988 as part of the Tropical Ocean‐Global Atmosphere program. Located between regions of warm (cold) sea surface temperature in the western (eastern) equatorial Pacific, this west central region exhibits large interannual variations in surface wind stress associated with the El Niño‐Southern Oscillation. Here we report on the first 3 years of data collected at 0°, 170°W, exclusive of an El Niño event. The west central Pacific is a region through which the Equatorial Undercurrent (EUC) accelerates downstream. The vertical position of the EUC core, the vertical penetration of the South Equatorial Current (SEC), and the vertically integrated zonal volume transport all show large annual cycles. Annual and higher‐frequency transport variations are due primarily to fluctuations occurring above the thermocline, as opposed to within the EUC itself. Unlike the EUC position, the EUC core speed remains relatively steady annually, except during boreal fall and winter, when short duration, zonal momentum pulses generated as Kelvin waves to the west reduce the EUC to minimal values. Interannually, the EUC core speed was highest in 1988, and it has decreased, on average, since then. Also during 1988, tropical instability waves, generally observed farther east, were well developed at 170°W, while not in subsequent years. This suggests the same role interannually as annually for these waves: to smooth out heat and momentum gradients that form in response to the wind stress. (The winds in 1988, following the 1986–1987 El Niño, were stronger than in subsequent years.) At higher frequencies, evidence exists for an inertial‐gravity wave mode previously identified in nearby Canton Island sea level records.

Simulation ozone model in the middle atmosphere of the Northern Midlatitudes

All available radiance measurements collected from satellite experiments to measure ozone since 1978 are used to simulate vertical ozone structure in the middle atmosphere at middle latitudes of the northern hemisphere. This simulation is made for each month of the year separately, and for the latitudes 30°N, 40°N and 50°N, extending from 20hPa to 0.03hPa pressure levels. The intermidiate pressure levels we have used are twenty six. Equations giving the zonal mean ozone volume mixing rations as a function of both height and time are also presented.

Seasonal variations in equatorial Atlantic Ocean zonal volume transport at 28°W

Zonal volume transport is examined over the upper 150 m of the water column at 28°W, using the Seasonal Response of the Equatorial Atlantic experiment moored current meter data at 0.75°S, 0.0°, and 0.75°N and a time domain empirical orthogonal function (EOF) analysis to improve spatial and temporal resolution. Gaussian distributions are fit to the mean volume transports per unit width and the fluctuations about these means that are found to be represented by a single EOF mode. The mean volume transport is distributed symmetrically both about the equator and about 75 m depth, with a meridional scale width of 101 km and a magnitude of 20.3 Sv. The standard deviation for the fluctuations is 4.7 Sv, and in contrast to the mean the fluctuations are confined to above 100 m depth, with a larger meridional scale width. The scale width for the mean is consistent with an inertial scale associated with conservation of potential vorticity, while the scale width for the fluctuations is consistent with an equatorial Rossby radius of deformation associated with equatorially trapped waves. These findings support a hypothesis that different physical processes are controlling the volume transport, as integrated from the surface across the Equatorial Undercurrent, over different time scales. On the time scale of the record length average, inertial dynamics appear to be controlling, while on the time scales of the seasonal fluctuations, linear equatorial long‐wave dynamics appear to be controlling. However, given the limited record length, there are insufficient degrees of freedom to test this hypothesis statistically.

Tracer gas mixing with air

The tracer gas method is one of the most widely used methods for measuring flow rates for building air infiltration and ventilation. The accuracy of this method depends vitally on the spatial uniformity of the tracer/air mixing. However, information on this critical problem has been scarce, largely due to the practical difficulty in experimentally obtaining data. In the last decade a new tool for building research has emerged, namely computational fluid dynamics or CFD. A study of tracer/air mixing has been carried out using a time dependent CFD method, supported by conceptual/dimensional analysis. In this study, 12 cases of tracer/air mixing in simulated tracer decay tests were computed. Each case had a different zonal volume or other boundary or initial conditions. By comparing these results, it was found that there were many factors affecting tracer/air mixing and, contrary to a previous report, there does not exist a universal critical value of air change rate below which satisfactory mixing is guaranteed, although lower air change rates are generally beneficial to mixing. In addition, it has been demonstrated that smaller building zones and higher inlet air flow velocities have positive effects on tracer/air mixing while the initial tracer concentration level has no effect. Finally a statistical parameter of concentration spread coefficient for assessing tracer mixing has been introduced.

Maturational Differences in Hepatic Microhemodynamics in Rats

Age-related changes in the hepatic microcirculation may contribute to the increased susceptibility of the immature liver to microvascular injury. We quantified sinusoidal and acinar diameters, sinusoidal red cell velocities (VRBC), and sinusoidal volume flows to characterize microhemodynamics of weanling and adult rat livers with and without hepatic artery (HA) ligation using intravital fluorescence videomicroscopy. Despite a 20% faster heart rate and a nearly 20% lower mean arterial and portal vein pressure in weanling rats relative to those in the adults, weanling periportal and pericentral sinusoidal velocities were ∼30 and 25% faster, respectively, than those in adults. Furthermore, the HA was found to contribute more to maintenance of sinusoidal VRBC in the immature liver as demonstrated by a significant decrease in both periportal and pericentral VRBC following HA ligation. HA ligation had no effect on VRBC of either zone in adults. Zonal volume flow (HA intact), however, was maintained independent of age. These results suggest a lower extrasinusoidal resistance in the weanling. The 25% shorter acinar diameter that we found in weanling livers likely contributes to a lower extrasinusoidal resistance by allowing a higher ratio of inflow vessels to volume of tissue. Shorter sinusoidal pathways in weanling livers also decreases sinusoidal resistance 1.3-fold relative to that in the adult, countering the ∼1.5 times increase in resistance due to the smaller caliber of sinusoidal vessels so that overall sinusoidal resistance is not age-dependent. The apparent susceptibility of the pediatric liver to vascular injury under conditions such as reperfusion following ischemia may, hence, reflect an underlying immaturity of hepatic presinusoidal, sinusoidal, and postsinusoidal microvascular anatomy and of vasoregulatory mechanisms.

The response of the western equatorial Pacific Ocean to westerly wind bursts during November 1989 to January 1990

Several 5 to 10 m s−1 westerly wind bursts of 10–15 days' duration occurred in the western equatorial Pacific during November 1989 to January 1990. The response to these wind bursts was characterized by a 400‐ to 600‐km‐wide eastward jet in the upper 100–150 m along the equator between 135°E and the date line. Flow in this jet accelerated to speeds of over 100 cm s−1 within 1 week after the onset of westerly winds in November 1989 in association with supertyphoon Irma. In addition, a 20 to 40 cm s−1 westward counterflow developed between 2°N and 2°S below the surface jet separating it from the eastward flow of the Equatorial Undercurrent in the thermocline. Changes in surface layer zonal volume transports in the western Pacific due to westerly wind bursts were 25–56 Sv based on comparison of three shipboard velocity transects in November and December 1989. Although fluctuations in current speeds in the thermocline were generally smaller and less directly related to local wind forcing than those in the surface layer, the Equatorial Undercurrent decelerated to less than 20 cm s−1 (i.e., less than half its speed before the onset of westerlies) by early December 1989. Westerly winds also produced a strong surface convergence in both the meridional and zonal directions west of the date line. In late November 1989, this convergence was associated with downwelling of 2–3 m d−1 along the equator, and a 20‐ to 30‐m depression of the thermocline. In addition, sea level rose by 10 dyn cm from mid‐November to mid‐December between 1°S and 3°N, 165°E. Sea surface temperature dropped over a large region by 0.2°–0.5°C during episodes of high westerly winds, and some episodes of high winds were associated with 0.2°–0.3°C sea surface temperature inversions supported by salt‐stratified buoyancy gradients in the upper 100 m. The near‐surface salinity balance was dominated by lateral advection when relatively fresh water from north of a salinity front centered near 3°N was advected southward by Ekman drift in late November 1989. Displacement of this front past a current meter mooring at 0°, 165°E, appeared as a local drop of 1 psu in surface layer salinity in 10 days. These results are discussed in the context of a swing in the climate system towards El Niño‐Southern Oscillation‐like conditions in early 1990.

Structure and function changes in rat adrenal glands during aging.

The current study examines corticosterone production in young and old rats with a view to understanding how hormone production is related to aging changes in the adrenal gland. For this purpose, we compared total (plasma volume-corrected) values for adrenocorticotropic hormone (ACTH)-induced maximal corticosterone production in young, mature (5-mo-old), and aging (18-mo-old) rats. These values were subsequently corrected for measured age-related differences in adrenal weight, adrenal cortex volume, specific adrenal zone volumes, and total number of corticosterone-producing cells in the adrenals of the differently aged rats. In addition, corticosterone disposal rates were measured in the two groups of rats, and adrenal cortical ACTH binding sites were identified by autoradiography after perfusion with 125I-labeled ACTH analogue. The results show that maximal serum ACTH-induced corticosterone concentrations (per ml serum) in the 18-mo-old rats are somewhat less than those seen in the younger animals. However, because the plasma volume is greater in the older animals (and corticosterone disposal rates do not vary), total circulating corticosterone production is, in fact, equivalent in the two groups of animals. When these total values for corticosterone are corrected for various structural changes in the adrenal gland with age, corticosterone production was found to be lower in the older group of rats: i.e., one sees an approximately 50% decline when corticosterone is expressed per adrenal weight or zonal volume and an approximately 20% decline when expressed per number of endocrine cells per adrenal.(ABSTRACT TRUNCATED AT 250 WORDS)

Short-Term Climatic Variability in the Volume Budget of the Western Tropical North Pacific Ocean during 1979–82

Abstract Anomalous 14°C isotherm depth and anomalous geostrophic volume transport above the 14°C isotherm depth are calculated in the tropical Pacific for each bimonth of the four year period 1979 to 1982, based on 15 000 temperature/depth observations made by volunteer observing ships. The first two eigenfunctions (EOFs) of the anomalous 14°C isotherm depth, the anomalous zonal geostrophic volume transport, and the anomalous meridional Ekman volume transport explain 44%, 32% and 47% of their variances, respectively. Most of the variability explained by the first EOF is associated with the 1982–83 ENSO event. The EOFs indicate that a loss of anomalous volume above the 14°C isotherm in the western tropical North Pacific is correlated with an increase in anomalous volume in the eastern equatorial Pacific. There is a simultaneous intensification of anomalous eastward geostrophic currents across the width of the equatorial Pacific; however, from 150°E to 140°W there is also a simultaneous intensification of a...

Adrenal cortex of the dog (Canis familiaris). I. Histomorphologic changes during growth, maturity, and aging.

AbstractThe adrenal glands of 56 dogs ranging in age from birth to 13.6 years were examined for a determination of normal zonal and cellular morphology patterns throughout development, maturity and aging. Routine light microscopic techniques as well as lipid and cholesterol staining were used. The zona arcuata is described as developing between the fibrous and cellular layers of the capsule forming the cortical blastema layer, a zona biproliferativa. It is proposed that both centrifugal and centripetal migration of cortical parenchyma can result. The formation of accessory nodules is described as compensatory hyperplasia. Histomorphometric analysis revealed growth in the zona fasciculata to be by hyperplasia and the zonal volume percentages to be arcuata, 27%; fasciculata, 50%; reticularis, 23%.

Circular structures in the Arctic Islands

OBJECTIVE: To investigate the effects of a one year programme of running training (up to 40 km/day for 15 weeks) on the spatial orientation pattern of collagen and glycosaminoglycans in articular cartilage in different parts of the knee (stifle) and shoulder joints of young beagle dogs. METHODS: Area specific measurements of the optical path difference (= retardation, gamma) and the cartilage zone thickness were performed using conventional procedures and a new computer based quantitative polarised light microscopy method. Transmission electron microscopy was used to determine the zonal volume density of collagen fibrils. The concentrations of collagen and hydroxypyridinium crosslinks were investigated biochemically. RESULTS: Running training decreased gamma by 24-34% (p < 0.05) in the superficial zone of the lateral femoral condyle articular cartilage and at the centre of the tibial condyles. Gamma of glycosaminoglycans decreased by 26% (p < 0.05) in the superficial zone of the lateral condyle of the femur, but at the same site the volume density of collagen fibrils was unchanged. Neither the collagen concentration nor the concentration of hydroxypyridinium crosslinks was altered as a result of running. In both control and runner dogs, the thickness and gamma values of the superficial zone were greater in the humerus and the femur than in the tibia. CONCLUSION: Endurance type running exercise in beagles caused a reduction in the superficial zone birefringence of the articular cartilage, which indicates either a disorganisation or a reorientation of the superficial zone collagen network. Articular cartilage showed marked variability of collagen network organisation over the different knee (stifle) joint articular surfaces.