Isobaric Surfaces Research Articles

The atmosphere of Neptune: Results of radio occultation measurements with the Voyager 2 spacecraft

Radio tracking data acquired during Voyager 2's occultation by Neptune have been used to study the thermal structure and composition of Neptune's troposphere and stratosphere. The occultation began near 62° North planetographic latitude and aided near 45°South latitude. The data cover an altitude interval of about 250 km. A comparison with infrared observations indicates that the gas at the tropopause, which was observed near the 100 mbar level, consists of 77 to 85 % hydrogen by number density with the remainder being mostly helium. A layer with a small refractivity scale height that was detected approximately 50 km below the tropopause, may be a region where the CH4 mixing ratio is decreasing with increasing altitude due to condensation effects. This interpretation leads to a CH4 mixing ratio of 1 to 2 % by number density at the base of the layer where the pressure is approximately 1.7 bars. The depth of the occultation measurements was limited by microwave absorption. By assuming that the absorption was caused by saturated NH3 vapor, one obtains a pressure, temperature, and NH3 mixing ratio of 6 bars, 130 K, and 600 parts per billion, respectively, at the lowest level where the radio link was detected. For internal consistency, this solution requires an atmospheric rotation period of 14.2 ± 0.5 hours near 60° North latitude which corresponds to a prograde zonal wind velocity of 170 ± 50 m/sec relative to the magnetic field. The 1 bar isobaric surface has an equatorial radius of 24,764 ± 15 km and a polar radius of 24,341 ± 30 km. The corresponding oblateness, (Req‐Rp)/Req, is 0.0171 ± 0.0014.

Mesoscale patterns of chlorophyll a in the Central North Pacific

Within the Central North Pacific along latitude 24°15'N, a mesoscale spatial pattern of chlorophyll a, with a scale of 500 km, dominates basin-wide patterns. West of the Hawaiian Ridge, the dominant scale of near-surface dynamic topography, apparently baroclinic eddy activity, is also 500 km, and the mean variance functions of dynamic height and chlorophyll are coherent. East of the ridge, however, the dynamic topography is dominated by the eastward slope of the isobaric surfaces related to the slow southward transport of near-surface water. Mesoscale patterns of dynamic topography are not apparent, and the relationship between chlorophyll and dynamic topography is unclear. West of the Hawaiian Ridge, higher values of chlorophyll are associated with the centers of cyclonic eddies, lower values with anticyclonic eddies. The pattern of chlorophyll a cannot be explained by concentration and dispersion of cells in the regions of convergence and divergence, but it may involve a combination of growth and depth regulation in response to ambient conditions. There is a loss of nitrate associated with the upward displacement of isopycnal surfaces which accompanies the eddy activity. This doming of subsurface isopycnal surfaces may act as a nutrient pump bringing nitrate into the euphotic zone. Thus, temporal and spatial variations of eddy activity may account for some of the variations in production in the Central North Pacific.

An explanation of light-curve asymmetries in contact binaries by means of the Coriolis effect

In this study, it is proved that the isothermal surface is not identical with the isobaric surface in a static model of a contact binary system based on hydrostatic and thermal equilibrium equations. Therefore, there is a baroclinic structure in a contact binary atmosphere, and the development of circumfluence is thus inevitable. It is suggested that a static model should not be adopted in modeling a contact binary atmosphere. The asymmetry (different brightness between the maxima) commonly found among the light curves of W UMa binary systems can be explained in terms of the asymmetry of circumfluence in the contact binary stars due to the Coriolis effect. 8 refs.

Reconstruction of O3 and N2O fields from ER‐2, DC‐8, and balloon observations

Measurements of N2O and O3 during the Airborne Arctic Stratospheric Expedition have been composited using the potential vorticity and potential temperatire of each measurement as coordinates. For ozone, data sources included the ER‐2 and balloon ozonesonde in situ measurements, DC‐8 DIAL lidar, and SAGE satellite profiles. For N2O, only ER‐2 data were used. These chemical composites have been reconstructed onto average meteorological fields for the mission in a latitude‐altitude cross‐section, yielding a picture of the chemical composition of the polar vortex during this period. Tracers inside the vortex show an apparent descent of about 2 km relative to those outside, resulting in an apparent chemical edge on isentropic and isobaric surfaces.

Anomalies of the upper-wind field induced by the Alpine Chain during winter

An analysis of the cross-correlation of the vectors of the upper wind at the principal isobaric surfaces over Milan, Udine, Rome, Cagliari and Brindisi, shows a marked anomaly in the wind field over Udine at 850 hPa. This is due to disturbances caused to the mesoscale circulation by the Alpine Chain. Over the summit of the Alps, the wind field is homogeneous over the whole of Italy, except near the tropopause. The correlation coefficient can be expressed as a function of the distance between the wind vectors considered on the same isobaric surface, by means of an exponential attenuation.

A Theoretical and Diagnostic Study of Solitary Waves and Atmospheric Blocking

Abstract Theories which associate atmospheric blocking with isolated “free mode” solutions of the equations of motion are reviewed and the central role played by the potential function Λ ≡ dq/dψ (where q is the is the quasi-geostrophic potential vorticity and ψ is the streamfunction) is emphasized. This function provides the common dynamical link that draws together the weakly nonlinear (soliton) and fully nonlinear (modon) theories of isolated coherent structures. A diagnostic study of the European blocking episode during October 1987 is presented and the relationship between q and ψ investigated by plotting scatter diagrams of quasi-geostrophic potential vorticity against the streamfunction on an isobaric surface. An approximate functional relationship is found allowing Λ to be defined. Over the blocking region, points on the scatter plot cluster around a straight line which is more steeply sloping than the straight line defined by points from nonblocking regions, demonstrating that the block exhibits a...

Tangential discontinuities and the optical analogy for stationary fields II. The optical analogy

Abstract It is shown that any stationary three-dimensional velocity field or magnetic field is a potential field in the two dimensional subspace of the Bernoulli surfaces S(Q) or isobaric surfaces S(p), respectively. From this it is shown that the streamlines and the lines of force follow the optical ray paths in S(Q) and S(p) for indices of refraction v and B, respectively. This formal analogy shows how the lines are refracted by variations of the pressure applied by the fluid and field on either side. In particular, it is shown how continuous variations of the pressure produce discontinuities (bifurcations) in the field, forming tangential discontinuities.

Statistical relations between winter monsoon Rainfall and the preceding summer monsoon

The mean monthly wind vectors at 7 standard isobaric levels and surface parameters of several stations of the summer (southwest) monsoon months of June to September over India have been examined. The objective was to select predictors for the northeast monsoon rainfall of the Indian Peninsular subdivisions of TamilNadu, Kerala, coastal Andhra Pradesh and Rayal3seema. The data for a 33-year period (1951-83) were used in this study. A sequence of screening tests were employed to select reliable predictors for these subdivisions. It has been shown that the August-September 150 mb zonal mean wind of Trivandrum is capable of giving satisfactory forecasts for the following northeast monsoon rainfall of Tamilnadu. The constraints in using multiple predictors have been discussed.

A generalized equation for surface tension from the triple point to the critical point

A three-parameter generalized equation is proposed for surface tension from the triple point to the critical point. This equation not only fits the data well but also is good for interpolation between the normal boiling point and the critical point. This equation is also good for extrapolation to the triple point. This equation has been tested using the surface tension of water from the triple point to the critical point. The constants of this equation obtained using orthobaric surface tensions are given for a number of compounds. The isobaric surface tensions determined at a pressure of 1 atm do not differ significantly from the orthobaric surface tensions. Such data also have been used in obtaining equations from the triple to the critical point.

Complex Quality Control of Meteorological Observations

A survey of the so-called complex quality control (CQC) of meteorological information is presented. The principles of the CQC approach are formulated. The CQC of rawinsonde height and temperature data at mandatory isobaric surfaces is described in detail. This CQC has been implemented into routine practice at the Hydro-meteorological Center in Moscow. It has been also applied at the World Data Center in Obninsk for the quality control of the FGGE Level IIb data. Some results of the CQC operations are presented. Possibilities and ways to apply the CQC approach to other kinds of meteorological information are also discussed.

An airborne gravity study of eastern North Carolina

The Naval Research Laboratory (NRL) has developed a prototype airborne gravity measurement system. The core of the system is a LaCoste and Romberg air‐sea gravity meter mounted on a three‐axis stable platform. Corrections to the gravimeter data for altitude and variations in altitude are determined from a combination of highly precise radar and pressure altimeters. The original prototype system was designed for use over oceanic areas. We recently incorporated the pressure measurement to extend use of the airborne system to terrestrial regions where occasional radar altitudes over points of known topographic height can be obtained. The radar heights are used to relate the pressure altitudes to absolute altitudes and to determine the slopes of the isobaric surfaces. Vertical accelerations due to horizontal velocity over a curved, rotating earth (the Eötvös correction) and precise two‐dimensional positions are determined from a Texas Instrument P-code global positioning system. The updated system was tested over eastern North Carolina and the Outer Banks, an area that is difficult to survey by conventional means. Over one‐third of the region consists of low lying swampy terrain and another one‐third is the shallow water of the Pamlico and Albemarle Sounds. Neither the land method nor the shipboard gravity surveying method is well suited for these types of areas. Flying at an altitude of 600 m at 375 km/hr, we were able to cover an area over [Formula: see text] with a nominal track spacing of 9 km by 9 km in less than 18 hours of flying time. A comparison by the Defense Mapping Agency showed a 2.8 mGal rms and a −0.2 mGal mean difference between ground truth data and the airborne data at grid points when both data sets were interpolated to a common 9 km grid.

On the helical nature of neutral trajectories in the ocean

A neutral tangent plane is defined so that small isentropic and adiabatic displacements of a fluid parcel in this plane do not produce bouyant restoring forces on the parcel. This local stability argument can also be used to trace a neutral trajectory in space along some pre-determined path in latitude and longitude. If one integrates laterally around an entire ocean basin on a neutral trajectory, one can arrive at a different depth than that of the starting point on the original CTD cast. This means that the definition of a neutral surface is path-dependent. This is a real effect; it results from the complicated equation of state of seawater, and is not an artifact of errors in the lateral integration procedure. Dyed patches of fluid are mixed laterally by meso-scale eddies along these neutral helices, and at the same time they are smoothed and advected in the vertical direction by small-scale mixing processes. It is shown that, while a neutral surface is formally ill-defined mathematically (in the above path-dependent sense), this is of little importance for the purpose of constructing lateral maps of properties in the ocean, since the ambiguity in constructing a neutral surface is often less than the measurement accuracy of modern oceanographic instruments (≈0.003 kg m −3 in density). Path-dependence in the definition of a neutral surface occurs because α/β is a function of pressure (where α and β are the thermal expansion and haline contraction coefficients respectively). The local contribution to path-dependence is proportional to ▽ p· ▽ Sx ▽ Sxθ , representing the angle between an isobaric surface and the line of intersection of an isohaline surface and a surface of constant potential temperature. This, in turn, is proportional to ▽ n px ▽ nθ where ▽ n is the epineutral gradient operator for properties measured in a neutral tangent plane. That is, unless isobars and potential isotherms drawn in a neutral tangent plane are parallel, a neutral trajectory around this point will not lie in the plane, but will describe a helix in space. Although complete surfaces with the “neutral property” do not exist, the neutral tangent plane is everywhere well-defined. The lateral motion along helical neutral trajectories produces vertical advection in the ocean. A method is described in this paper of taking an approximately neutral surface and distributing the path-dependent effects over the surface in a least-squares sense. At each point in the ocean an error vector is found that represents the difference between the “best-fit” surface (which is a mathematically well-defined surface) and the local slope of the neutral tangent plane, providing a rational way of distributing the path-dependent vertical velocity on the surface. The vertical fluxes of heat, salt or tracer produced by the path-dependence of neutral surfaces do not have a signature in the dissipation rate of mechanical energy that can be measured with microstructure instrumentation.

夜間の安定層の破壊に及ぼす地形の影響 ＩＩ 安定層の破壊速度と地形パラメータについて

Hayakita, which is surrounded by hills like a basin, has strong stable air layers due to radiative cooling and is compared with Chitose which lies in the center of Yuhutsu plain. The Hayakita area also suffers from frost damage since low temperatures remain until early morning (Matsuoka et al., 1987). It was considered that the upper wind plays an important role in maintaining stable layers in Hayakita. In this study, relations between upper wind speed and surface wind speed were investigated.Wind speeds were measured at Hilltop as well as at Hayakita and at Chitose. The wind speed at Hilltop was compared with the upper wind speed which is at the 900mb isobaric surface, above Sapporo (V900). The analysis revealed;i) Wind speed at Hilltop (UT) is greater than 2m/sec.ii) Wind speeds at 900mb and 800mb isobaric surface above Sapporo (V900 and V800 respectively) are greater than 2m/sec.iii) Vertical shear (|V900-V800|) is less than 6m/sec.The regression equation between wind speed at Hilltop and at 900mb isobaric surface is given in eq. (1). The correlation coefficient (r) is significant to 1% level. Thus it may be stated that the wind speed at Hilltop represents upper wind speed at the 900mb isobaric surface.The relations between wind speed at Hilltop (UT) and, those at Hayakita and Chitose (UH and UC respectively) were investigated on cloudy nights. It was considered that this type of situation, which was judged on the basis of 4-hour mean cloud amount being over 9.0 at the Chitose airport, has nearly neutral conditions aerodynamically. Eq. (2) shows relations between UT and UH, and, UT and UC. The gradient of the regression line for Chitose is greater than that for Hayakita. From the relation between UH and UC, eq. (3) was obtained using a hypothesis of logarithmic law of wind speed profile. The roughness parameters at Hayakita and Chitose were calculated to be 0.43m and 0.09m respectively, using the methods employed by Kondo and Yamazawa (1983). If this value at Chitose is substituted for Z0C in eq. (3), the roughness parameter at Hayakita (Z0H) is calculated to be 0.42m which is nearly equal to 0.43m as mentioned above. Thus roughness parameter (Z0) shown by eq. (3) can express topographical feature.On the clear nights which have below 2.0 of mean cloud amount, the relations between wind speed at Hilltop, and wind speed at Hayakita or Chitose resulted by eq. (4). These nights have stable conditions aerodynamically. The gradients of the regression equations are smaller than those under the neutral conditions, but the tendency that gradient at Chitose is greater than that at Hayakita, remains in eq. (4).The relationship between the time taken to destroy stable layers by entrainment and topographical feature, was investigated on the nights when there was wind speed increases at Hilltop. The crosscorrelation between the sequence of wind speed at Hayakita (or Chitose), and that at Hilltop was calculated for this analysis. Under steady state conditions, time taken to destroy stable layers (L) is represented as eq. (8). By inputting observed values into eq. (8), the regression equations are given in eq. (9). The regression constant at Hayakita (B=1.13) is larger than that at Chitose (B=0.96). The hypothesis that B is a unique constant for each location is justified. Thus, if regression equations such as eq. (9) are determined, we can predict the duration of low temperature periods using potential temperature gradient in the stable layer and upper wind speed.

Rossby Wave Propagation an Beta-Planes

The numerical modeling of stratospheric, quasi-geostrophic Rossby wave propagation on a beta-plane channel is examined to determine how wave propagation is affected by the use of low horizontal (spectral) resolution. This study considers time dependent, quasi-linear, wave-mean flow interaction for typical wintertime conditions. Time dependent, wave-mean flow interaction modeling can show nonlinear behavior equivalent to quasi-horizontal planetary wavebreaking. Wave-mean flow interaction modeling requires relatively higher meridional resolution than is needed for the linear wave case because meridionally localized wave-mean flow interaction generally occurs. The interaction is viewed in terms of quasi-geostrophic potential vorticity on isobaric surfaces. The degree to which quasi-geostrophic potential vorticity is conserved locally as it is mixed quasi-horizontally by planetary waves under adiabatic conditions can be estimated by examining the evolution of the isobaric quasi-geostrophic potential vorticity, and this mixing is related to wave propagation by means of the Eliassen-Palm flux. It is shown that at lowest meridional resolution, where a single spectral mode is used to represent all meridional profiles, it is best to consider the channel model to be two dimensional in (x, z).

The atmosphere of Uranus: Results of radio occultation measurements with Voyager 2

During Voyager 2's occultation by Uranus the radio link from the spacecraft probed the atmosphere of the planet at latitudes ranging from 2° to 7° south. The measurements, which were conducted at two coherently related wavelengths, namely, 13 cm (S band) and 3.6 cm (X band), did not show any clear signs of microwave absorption. However, the Doppler frequency perturbations observed on the radio link have provided new data on the equatorial radius and atmosphere of the planet. From integral inversion of the Doppler data, profiles in height of the electron number density in the ionosphere and the gas refractivity, number density, pressure, temperature, and methane abundance in the troposphere and stratosphere have been determined. The gas data were acquired in the pressure range from about 0.3 mbar to 2.3 bars over an altitude interval of approximately 250 km. At the 2.3‐bar level the nominal model has a temperature of 101 K with a 1σ uncertainty of 2 K when the uncertainty in the composition is assumed to be negligible. The corresponding temperature lapse rate is 0.95 ± 0.1 K/km. A 2‐ to 4‐km‐thick layer with a small refractivity scale height was detected during ingress and egress, which is consistent with the presence of a methane cloud layer centered at the 1.2‐bar level. For the nominal model the methane mixing ratio below the base of the cloud is 2.3% by number density. At the tropopause, which was observed near the 100‐mbar level, the temperature is 53 ± 1 K. A comparison with infrared data acquired with the infrared interferometer spectrometer instrument on board the Voyager spacecraft indicates that the gas in this region consists of 85 ± 3% hydrogen with the remainder being mostly helium. Above the tropopause the gas temperature increases with increasing altitude, reaching 114 ± 10 K near the 0.5‐mbar level. Several warm layers, which may be produced by absorption of solar radiation by hydrocarbon aerosols, were detected in the stratosphere. From the data acquired at ingress and egress the shape and size of the isobaric surfaces of Uranus have been determined. The shape indicates that the gas in the region probed by the link rotates with an average period of about 18 hours, which corresponds to a zonal wind velocity of 110 m/s relative to the magnetic field. This implies that the equatorial atmosphere rotates slower than the interior, in contrast to the situation at Jupiter and Saturn. The 1‐bar isobaric surface has an equatorial radius of 25,559 ± 4 km. Extrapolating from the equator to the south pole by using available data on the gravity field and the zonal wind velocities gives a polar radius of 24,973 ± 20 km. The corresponding oblateness, (Req ‐ Rp)/Req, is 0.02293 ± 0.00080.

Theory of phase diagrams and azeotropic conditions for two-phase reactive systems

Expressions for the partial derivatives of the intensive properties that characterize the equilibrium states in two-phase systems, in which the components undergo one equilibrium chemical reaction, are derived. The necessary and sufficient conditions for an azeotropic transformation to occur are found. It is shown that whereas stationary points in the isobaric temperature-composition or isothermal pressure-composition equilibrium surfaces correspond to the formation of reactive azeotropes, reactive azeotropes do not necessarily correspond to stationary points in these equilibrium surfaces. The conditions under which reactive azeotropes are not equivalent to stationary points in the equilibrium surfaces are presented.

Alpine metamorphism of pelitic schists in the Nufenen Pass area, Lepontine Alps

Abstract The effects of Tertiary Alpine metamorphism on pelitic Mesozoic cover rocks have been studied along a cross‐section in the central Lepontine Alps in the Nufenen Pass area, Switzerland.Greenschist facies to amphibolite facies conditions are indicated by the formation of the index minerals chloritoid, garnet, staurolite and kyanite in pelitic rocks. Regional metamorphism reached maximum conditions during the interkinematic period between a main Alpine penetrative (D2) and a late Alpine (D3) crenulation type deformation phase or synchronous with the late Alpine deformation. Based on AFM phase relationships four different metamorphic zones can be distinguished: (1) chloritoid zone; (2) staurolite + chlorite zone; (3) staurolite + biotite zone; and, (4) kyanite zone.The isograds that separate these zones can be modelled by univariant reactions in the KFMASH system. The conditions of metamorphism calculated from geological ther‐mobarometers for the maximum post‐D2 por‐phyroblast stage are from North to South: 500° C at 5‐6 kbar and 600° C at 7‐8 kbar.Detailed thermobarometry of garnet por‐phyroblasts with complex textures suggests that maximum temperature was reached later than maximum pressure. Early garnet growth occurred along a prograde P‐T‐path, post‐D2 rims grew with increasing temperature but decreasing pressure, and finally post‐D3 garnet formed along a retrograde P‐T‐path.It may be concluded from the calculated pressure and temperature difference over a short distance (3 km) across the mapped area that the isogradic surfaces of the post‐D2 metamorphism are steeply oriented. The data also suggest that isobaric and isothermal surfaces are parallel.Much of the observed metamorphic pattern can be explained as the result of a significant post‐D2 differential uplift of the hot Pennine area relative to the Helvetic area along a tectonic contact zone. The closely spaced isograds (isotherms) in the North may then be interpreted as a thermal effect owing to the emplacement of the hot Pennine rocks against the Got‐thard massif with its cover. Whereas, in the Pennine metasediments, post‐D2 porphyroblast formation can be related to the decompression path which was steep enough for dehydration reactions to proceed. It is also remarkable that late kyanite porphyroblasts probably formed with decreasing pressure.The interpretation given here for the Nufenen Pass area may also apply to the Luk‐manier Pass area where similar metamorphic patterns have been reported by Fox (1975). The formation of the ‘Northern Steep Belt’;, as denned by Milnes (1974b), and the associated late Alpine fold zones may, therefore, have significantly modified the metamorphic pattern of the Helvetic‐Penninic contact zone.

Topographic Effects on Destruction of Stable Layer during Nighttime

To research regional difference of frost damage, meteorological observations were made at Hayakita, located in the south-east of the Ishikari-Yuhutsu plain in Hokkaido. Hayakita has crops that are the most easily damaged by frost in the plain. In particular paddy rice plants are damaged by the first frost when their growth is retarded by a cool summer. The first frost in Hayakita occurs 1 week earlier than in other parts of the plain. To research this problem, Chitose that has different topography from Hayakita, was selected as a control area and some meteorological factors such as air temperature, wind speed, solar radiation, net radiation and downward radiation were compared between Hayakita and Chitose. These areas are at the same altitude and share similar surface features. Although Hayakita is surrounded by hills, Chitose is in the center of the plain and is located 12 kilometers away from Hayakita.In this paper, the daily minimum air temperatures and 4-hour mean values of the meteorological factors in the springs and falls of 1983 and 1984 were compared between Hayakita and Chitose. Also the variations of these factors on clear nights were compared.Daily minimum air temperatures in both seasons were not significantly different between Hayakita and Chitose. This means that the advection and accumulation of air mass cooled on surrounding slopes are not significant as causes of the frost damage in Hayakita.The 4-hour mean value of wind speed at Chitose was always greater than that at Hayakita. However, there were no significant differences for the other factors, such as solar radiation, net radiation and downward radiation between Hayakita and Chitose. The air temperature in Hayakita was often lower than that in Chitose, especially in the lower range of temperatures. This tendency was more remarkable in fall than in spring. Sometimes the temperature difference between the two regions reached approximately 5K in fall, accompanied with a large difference of wind speed.This large difference of air temperature tended to be observed from 20:00 to 4:00 of clear nights. It was caused by temperatures in Chitose often being rapidly increased by raising wind speed during that time, but both temperature and wind speed in Hayakita remained low and unchanged. When comparing temperature profiles to 80 meters above ground level of both regions, it was noted that the stable layer formed by radiative cooling was destroyed from upper portion to near ground surface at Chitose, while, on the other hand, only the upper portion of the layer was destroyed at Hayakita. However, both stable layers remained during the nights when no temperature difference occurred between the regions. Therefore, the occurrence of temperature differences between the regions is due to the difference in the destruction ratio of the stable layer.The phenomena mentioned above, often appeared in the center of the plain when the upper wind (geostrophic wind) speed and/or direction changed. The upper wind data were obtained from radiosonde data at the 900mb isobaric surface above Sapporo. The changes of wind were classified by following two patterns: i) upper wind speed very small at first, becoming stronger later, and ii) upper wind direction changing from a direction in which WSR (Wind Speed Ratio: the ratio of surface wind speed to upper wind speed at a direction) is small to other one in which WSR is greater. Greater WSR means greater wind speed at ground level for a given upper wind speed; WSR is influenced by surrounding geographic features. Therefore, the WSR values at the center of the plain, lying between the high mountains to the east and west, were large for the north-south direction and small for the east-west direction. On the other hand, WSR values were relatively small for all directions in Hayakita. Thus wind speed in Hayakita was always smaller than that in the center of the plain.It can thus be recognized that low temperatures conti

On the consequences of non‐negative absolute vorticity

AbstractIt is shown that if the flow on an isobaric surface is such that the wind and mass fields satisfy the gradient wind equation, then the gradient of the Bernoulli function (the sum of the kinetic energy per unit mass and the geopotential) is everywhere perpendicular to the local wind vector and that, furthermore, if the absolute vorticity is non‐negative, the direction of increase of the Bernoulli function bears the same relation to the wind vector as does the direction of increase of the geopotential to the geostrophic wind. Applications of this relationship are discussed.

Detection, Structure, and Origin of Extreme Anomalies in a Western Atlantic Oceanographic Section

Abstract Ten anomalous water parcels were detected in the water column of a western Atlantic oceanographic section (0–5550 m; 70°W; 23–33°N). The parcels had extreme properties lying either two standard deviations from historical mean values, or estimated origins lying 2000 km from the oceanographic section. Detection, structure, and origin of the parcels were determined from analyses on isobaric and isopycnal surfaces using eight kinds of measurements temperature, salinity, oxygen, light scattering, silicate, phosphate, nitrate, and tritium. The parcels originated from seven of the major water masses comprising the North Atlantic Ocean. As observed along the oceanographic section the parcels had the following average (range) characteristics vertical pressure extent = 650 db (100–150 db); horizontal extent = 130 km (30–260 km); and distance to origin = 2300 km (400–5200 km). A population density equaling approximately one parcel per 100 km was obtained as the number of parcels (10) divided by the length o...