bluuebunny/crossref_metadata_2025 huggingface dataset:
The movement and decay of ice edge bands in the winter Bering Sea
Authors: Martin Seelye , Kauffman Peter , Parkinson Claire
Published: February 2008

During periods of off‐ice winds, the winter Bering Sea ice edge consists of ice bands that measure 1–10 km in length, 0.1–1 km in width, and are oriented at approximately right angles to the wind. The bands are composed of small floes 10–20 m in diameter and 1–5 m in thickness. In March 1981 working from the NOAA ship Surveyor, we mounted two radar transponders 4 km apart on ice floes within such a band and then tracked them for 46 h over an 80 km distance as the band moved into warmer water and melted. Comparison of the band position with that of a satellite‐tracked ARGOS station deployed in the ice interior shows that the band moved 30% faster than the interior ice. Analysis of our observations strongly suggest that the cause of the speed increase is the wind‐wave radiation stress on the upwind side of the band. We also observed that wind‐waves contribute to band ablation by the following mechanism: At the upwind edge, these waves break up the floes into small pieces. Because these pieces are no longer good wave reflectors or absorbers, they drift in the upwind direction away from the band to melt, so that the band width as well as the individual floe thicknesses decrease with time. In summary, because the bands provide an efficient way for the export and ablation of sea ice, the bands play a major role in the maintenance of the ice edge position.
The evolution of latitudinal shear in Rossby gravity wave, mean flow interaction
Authors: Dunkerton Timothy J.
Published: February 2008

The effects of latitudinal mean wind shear on the Rossby gravity wave are investigated. It is shown that this wave stabilizes barotropically unstable mean flows near the equator. Easterly curvature expands the wave scale and helps to insure the relevance of this theorem. It is also suggested that latitudinal shear, if incorporated into a Holton‐Lindzen type experiment, might act to produce a correct asymmetry in shear zone strength in the two phases of the quasi‐biennial oscillation.
SEASAT synthetic aperture radar observations of wave‐current and wave‐topographic interactions
Authors: Meadows G. A. , Shuchman R. A. , Tseng Y. C. , Kasischke E. S.
Published: February 2008

This study investigated the capability of a spaceborne, imaging radar system to detect subtle changes in the propagation characteristics of ocean wave systems. Specifically, an evolving surface gravity wave system emanating from Hurricane Ella and propagating toward Cape Hatteras, North Carolina, formed the basis of this investigation. This wave system was successfully imaged by the SEASAT synthetic aperture radar (SAR) during revolution 974 on September 3, 1978. Estimates of the dominant wavelength and direction of the ocean waves were derived from the SAR data by using optical Fourier transforms. Environmental data of the test area, which included the surface velocity vector within the Gulf Stream, the location of Hurricane Ella, and local bathymetric information, were used in conjunction with the SAR data to form the basis of this comparative study. Favorable agreement was found between wave rays calculated by utilizing theoretical wave‐current and wave‐topographic interactions and SAR observed dominant wavelength and direction changes across the Gulf Stream and continental shelf.
Atmosphere ‐ sea ice interactions in the Beaufort/Chukchi Sea and in the European sector of the Arctic
Authors: Crane R. G.
Published: February 2008

Electrically Scanning Microwave Radiometer (ESMR) data for ‘winter’ months, November 1973 to April 1974, and for ‘summer’, May to October 1974, are used to examine the synoptic scale sea ice‐atmosphere interactions over the Beaufort/Chukchi Sea and the European sector of the Arctic. The synoptic scale variability in the microwave brightness temperatures and sea level atmospheric pressure and temperature is examined through the use of principal components analysis. Changes occurring in the ice ablation season are found to be responsible for much of the variance in the data. Canonical correlations are used to derive the leads and lags in the ice‐atmosphere system. Positive feedbacks are identified between the ice and the atmosphere, and the direction of the ice‐atmosphere forcing is found to vary both seasonally and regionally, and also between the areas of permanent pack and the seasonal sea ice zone.
Transport and fate of river discharge on the continental shelf of the southeastern United States
Authors: Blanton J. O. , Atkinson L. P.
Published: February 2008

We have analyzed 8 years of wind and salinity data from a frontal zone in a region of the inner continental shelf off the southeastern United States. The changes in low‐salinity water stored in the frontal zone have been parameterized by analyzing the monthly rate of change in freshwater content. When the rate of change in freshwater content was negative, we interpreted this as a loss of low‐salinity water from the frontal zone. When this parameter was compared with seasonally averaged alongshore wind stress, the rate of loss was independent of the alongshore wind stress magnitude until threshold of about 0.1 dyne cm−2 was reached. Above the threshold there was a clear relationship between northward alongshore wind stress and rate of loss of freshwater from the inner shelf. Experimental evidence suggests that horizontal currents in the inner‐shelf frontal zone have cyclonic shear with increasing depth. When wind stress is northward and offshore, near‐surface low‐salinity water is transported offshore by Ekman transport while near‐bottom high‐salinity water is transported shoreward.
Fogwater chemistry in an urban atmosphere
Authors: Munger J. William , Jacob Daniel J. , Waldman Jed M. , Hoffmann Michael R.
Published: February 2008

Analyses of fogwater collected by inertial impaction in the Los Angeles basin and the San Joaquin Valley indicated unusually high concentrations of major and minor ions. The dominant ions measured were NO3−, SO42−, NH4+, and H+. Nitrate exceeded sulfate on an equivalent basis by a factor of 2.5 in the central and coastal regions of the Los Angeles basin but was approximately equal in the eastern Los Angeles basin and the San Joaquin Valley. Maximum observed values for NH4+, NO3−, and SO42− were 10.0, 12.0, and 5.0, meq 1−1, while the lowest p;H observed was 2.2. Iron and lead concentrations of over 0.1 mM and 0.01 mM, respectively, were observed. High concentrations of chemical components in fog appeared to correlate well with the occurrence of smog events. Concentrations in fogwater were also affected by the physical processes of condensation and evaporation. Light, dissipating fogs routinely showed the highest concentrations.
Southward subsurface flow below the Somali Current
Authors: Quadfasel Detlef R. , Schott Friedrich
Published: February 2008

The existence of a southward‐flowing current beneath the northern part of the seasonally reversing Somali Current is documented in a 2½‐year‐long time series of currents obtained at moored stations near 5°N about 30 km off the Somali coast. Its mean annual transport in the layer 150–600 m amounts to about 5×106 m3/s. The undercurrent has a pronounced seasonal cycle in phase with the near surface flow, suggesting a close coupling to the monsoonal wind forcing. With the spin‐up of the deepreaching northern Somali gyre after the onset of the southwest monsoon, the undercurrent is temporarily destroyed in the northern Somali Basin during June/July but is re‐established in August. The undercurrent does not reach 3°N but turns offshore north of that latitude.
The contribution of the Greenland and Barents seas to the deep water of the Arctic Ocean
Authors: Swift James H. , Takahashi Taro , Livingston Hugh D.
Published: February 2008

The deep waters of the Arctic Ocean are traditionally held to be fed by an influx of Norwegian Sea Deep Water (NSDW) via the northward flowing West Spitsbergen Current. Discrete sample and CTD observations obtained from the Greenland‐Spitsbergen Passage in August 1981 during the Transient Tracers in the Ocean (TTO) North Atlantic expedition showed a ≈ 100‐m‐thick layer of modified Greenland Sea Deep Water (GSDW: colder and fresher than NSDW) at 2500 m, spreading northward along the bottom of a deep, unimpeded channel, underneath the NSDW. Since the available data indicate that Arctic Ocean Deep Water (AODW) has a higher salinity than NSDW, mixing of NSDW and GSDW can not produce AODW. Therefore, other sources, such as the peripheral arctic shelf seas, must contribute dense saline water to the Arctic Ocean. Concentrations of 137Cs and 90Sr observed in AODW are greater than those observed in GSDW and NSDW. The concentrations of these radionuclides on the Barents Sea shelf are sufficiently high and in the correct relative proportions to support this proposition.
Dry‐fall of fine dust on sea
Authors: Foda Mostafa A.
Published: February 2008

The transport and fallout of dust during the advance of offshore dust cloud over water surface is studied. Some important issues concerning this problem are re‐examined, particularly the effect of water surface presence on the concentration field and deposition rates of dust. The analysis will show that an inner or surface layer may exist near the water surface, where surface retention or absorption processes are dominating and that large dust concentration gradients will be sustained there. A logarithmic concentration profile is shown to exist, extending from the surface roughness height throughout the surface layer thickness, which will be shown to be dependent upon the wind strength and the dust particles sedimentation velocity. The surface layer structure will not be dependent upon the particular profile assumed by the initial dust concentration at the land‐sea boundary, and the analysis will show that the dust fallout rates due to both sedimentation and surface absorption effects combined can be significantly larger than those commonly obtained by considering sedimentation effects alone. The theory can be used in assessing both the magnitude and the extent of aeolian sediments contribution to marine environment which exist adjacent to large desert area.
Variation in light intensity with height and time from subsequent lightning return strokes
Authors: Jordan Douglas M. , Uman Martin A.
Published: February 2008

Relative light intensity has been measured photographically as a function of height and time for seven subsequent return strokes in two lightning flashes at ranges of 7.8 and 8.7 km. The film used was Kodak 5474 Shellburst, which has a roughly constant spectral response between 300 and 670 nm. The time resolution was about 1.0 μs, and the spatial resolution was about 4 m. The observed light signals consisted of a fast rise to peak, followed by a slower decrease to a relatively constant value. The amplitude of the initial light peak decreases exponentially with height with a decay constant of about 0.6 to 0.8 km. The 20% to 80% rise time of the initial light signal is between 1 and 4 μs near ground and increases by an additional 1 to 2 μs by the time the return stroke reaches the cloud base, a height between 1 and 2 km. The light intensity 30 μs after the initial peak is relatively constant with height and has an amplitude that is 15% to 30% of the initial peak near the ground and 50% to 100% of the initial peak at cloud base. The logarithm of the peak light intensity near the ground is roughly proportional to the initial peak electric field intensity, and this in turn implies that the current decrease with height may be much slower than the light decrease. The absolute light intensity has been estimated by integrating the photographic signals from individual channel segments to simulate the calibrated all‐sky photoelectric data of Guo and Krider (1982). Using this method, we find that the mean peak radiance near the ground is 8.3×105 W/m, with a total range from 1.4×105 to 3. ×106 W/m.
A wave‐induced transport process in marine sediments
Authors: Harrison W. D. , Musgrave D. , Reeburgh W. S.
Published: February 2008

We show how surface wave action can increase the rate of transport of solutes into a sandy seabed by orders of magnitude via a mechanism known as mechanical dispersion. It is most effective for large sediment permeability and thickness, high surface wave amplitude, and shallow water. A method for setting up the appropriate transport equation, valid when dispersion is well developed, is given. Its dispersion term contains two mechanical dispersion parameters that can be estimated roughly from existing data when the sediments are well sorted. The dispersion can be inhomogeneous and anisotropic in homogeneous, isotropic sediments. The effect of surface wave action on transport into sediments on the eastern U.S. shelf is shown to be significant under certain conditions. The effect on thawing of subsea permafrost beneath Prudhoe Bay, Alaska, seems negligible.
Horizontal advection of temperature in the Drake Passage
Authors: Piola Alberto R.
Published: February 2008

The balance between low‐frequency local temperature variability and geostrophic horizontal advection of temperature in the deep waters in the central Drake Passage are analyzed using a 183‐day record of moored velocity and temperature data. Geostrophic horizontal advection accounts for about 70% of the observed temperature changes during this period. If imbalances between local changes and horizontal advection were only due to vertical advection, a downward velocity of about 15 (±10) m/day is required. A daily time series of vertical velocity, calculated from these differences, indicates that vertical motions are largest during two events when cold features, possibly associated with fluctuations of the Polar Front, pass through the site.
Sea ice effective microwave emissivities from satellite passive microwave and infrared observations
Authors: Comiso J. C.
Published: February 2008

Microwave sea ice emissivities are investigated on a global scale by using near‐simultaneous images from the temperature‐humidity infrared radiometer (THIR) and the dual‐polarization scanning multichannel microwave radiometer (SMMR), both onboard the Nimbus 7 satellite. The emissivities in several study areas in the Arctic region are observed to be approximately constant during a 9‐month period within the fall, winter, and spring months for both first‐year and multiyear ice, with a standard deviation of about 3%. During the onset of summer, when the snow cover starts to melt, emissivity increases of about 30% are observed at 37 GHz for multiyear ice, with the effect decreasing to less than 5% at the 6.6‐GHz channels. Multichannel cluster analysis over very large study areas during winter shows considerable variability in emissivities of well‐defined clusters of consolidated ice at 37 GHz and about one third as much at 18 GHz. Some nonlinearities in the functional relationship of the emissivities in the consolidated ice regions between first‐year and multiyear ice are also evident, especially when data from one frequency is plotted against that of another. However, the cluster analysis technique separates the various emissivity data points into distinct clusters corresponding to radiometrically different ice types. If the variability within each cluster is quantified and taken into account by using multispectral analysis, in addition to improving the capability of classifying ice by age, information about ice thickness and surface characteristics might also be obtainable.
“Layover” in satellite radar images of ocean waves
Authors: Gower J. F. R.
Published: February 2008

Present models explaining radar imaging of ocean surface waves have considered variations in radar cross section of the tilted or roughened surface and velocity bunching effects caused by the doppler shifts of moving scatterers. It is pointed out here that simple “layover” effects will cause an additional, significant modulation of the image brightness that increases the visibility of range‐traveling waves.
The Atmospheric Lifetime Experiment: 2. Calibration
Authors: Rasmussen R. A. , Lovelock J. E.
Published: February 2008

The calibration standards used in the Atmospheric Lifetime Experiment (ALE) for CFCl3, CF2Cl2, CH3CCl3, and CCl4 are described. This includes the preparation of the primary standards by static dilution and their propagation and stability for the period 1977–1982. Two independent assessments of the absolute concentrations of the primary standards used to initiate the ALE measurements in 1977–1978 are reported. For consistency in the ALE program the values assigned to the primary standards and subsequent working standards used in the field were not altered during the experiment when results of better estimates of the original concentration values were obtained. Rather, the appropriate factors ξ, by which the ALE mixing ratios for a given species should be multiplied to obtain our best estimate of the current concentration of a given species, are provided.
Enhancement of heavy ozone in the Earth's atmosphere?
Authors: Kaye Jack A. , Strobel Darrell F.
Published: February 2008

The possible enhancement of isotopically heavy ozone (50O3) in the earth's stratosphere and mesosphere produced by the preferential photodissociation of heavy oxygen (34O2) is considered. On the basis of a realistic oxygen‐only model, we show that the rapidity of the exchange reaction 18O + 32O2 ⇄ 16O + 34O2 prevents any enhancement at stratospheric temperatures. Since observations of Mauersberger (1981) suggest that such an enhancement exists, one is left with a paradox. Possible modifications to the chemical model, which include isotopically specific photochemistry of ozone, are shown to be non‐competitive with the exchange reaction.
An accurate radiative transfer model for use in the direct physical inversion of HIRS2 and MSU Temperature Sounding Data
Authors: Susskind J. , Rosenfield J. , Reuter D.
Published: February 2008

A detailed description is given of the direct computation of atmospheric transmittance and clear column radiances for the channels of HIRS2 and MSU as a function of atmospheric and surface conditions. Observations are compared with calculated radiances derived from colocated oceanic radiosondes. Under clear conditions, calculated brightness temperatures for the HIRS2 channels have a standard deviation of the order of 0.7°C compared with observations, while MSU channels have a standard deviation of about 1°C. Small biases are found in some channels that can be removed by an empirical ‘tuning’ with coefficients that can be successfully transfered from one season to another. Comparison of calculations with ‘reconstructed’ clear radiances, which are used in analysis of sounding data under partially cloudy conditions, show slightly poorer agreement. The radiance calculation, when used in a temperature retrieval algorithm based on finding solutions to the radiative tranfer equations, is shown to be accurate enough to allow for significant improvement of a poor initial on the one hand and only moderate degradation of a perfect initial guess on the other. A rapid transmittance algorithm giving atmospheric transmittances as a function of temperature profile, water vapor profile, ozone profile, and zenith angle of observation is described in the appendix and is shown to introduce insignificant errors in the radiative transfer calculations.
Simultaneous pulses in light and electric field from stepped leaders near ground level
Authors: Beasley W. H. , Uman M. A. , Jordan D. M. , Ganesh C.
Published: February 2008

During the summer of 1982 we used a collimated narrow slit and photomultiplier tube in conjunction with a broadband electric‐field system to study light and electric‐field signals from cloud‐to‐ground lightning flashes in Gainesville, Florida. For three flashes at a range of about 2 km, we observed correlated sequences of light and electric‐field pulses from sections of channel about 12 m long and about 80 m above ground for 50–100 μs prior to the first return strokes. These time intervals included all the leader light pulses that were recorded in each case. In one case there were at least nine distinct light pulses. Sometimes there were measurable electric‐field pulses preceding the first light pulse. Early or intermediate light pulses were the largest in amplitude. Electric‐field pulses generally increased in amplitude with time up to the return stroke. We interpret these observations as the result of leader steps passing through the field of view of the slit. Both light and electric‐field pulses occurred at intervals of 5–20 μs, had 10 to 90% risetimes of 0.5–0.9 μs, and had full widths at half maximum of 0.8–1.5 μs. We estimate that stepped‐leader speeds within 100 m of ground were between 0.8×106 and 3.9×106 m s−1.
The atmospheric chemistry of hydrogen cyanide (HCN)
Authors: Cicerone R. J. , Zellner R.
Published: February 2008

Since 1981, three groups have reported spectroscopic detections and measurements of hydrogen cyanide in the atmosphere. HCN concentrations (volume mixing ratios) of (1.5–1.7) × 10−10 appear to characterize the stratosphere and the northern hemisphere's nonurban troposphere. In this paper we explore the atmospheric behavior of HCN by examining its chemical and photochemical properties. Its principal sinks are reactions with atmospheric OH and O(1D); precipitation appears to be a negligible sink. In the stratosphere, vacuum UV photons also attack HCN. Atmospheric model calculations show that HCN should be relatively well mixed in the troposphere and that its concentration decreases slowly with altitude in the stratosphere. Its atmospheric residence time appears to be about 2.5 years, although 1–5 years is a possible range. To maintain the observed atmospheric burden of HCN, an annual source of about 2 × 10−11 g nitrogen as HCN is required; we speculate as to the identity of these sources. Oxidation of HCN by OH, while the major sink for atmospheric HCN, is not simple or direct. Instead, oxidation proceeds from the HCN·OH adduct formed in HCN + OH reactions. These pathways and their uncertainties are outlined here.
Latitudinal distributions and temporal changes of stratospheric HCl and HF
Authors: Mankin William G. , Coffey M. T.
Published: February 2008

Hydrogen chloride and hydrogen fluoride are important sinks in the stratosphere for free halogens. The major sources of chlorine and fluorine in the stratosphere are anthropogenic; therefore a measurement of HCl and HF gives information about the magnitude of anthropogenic effects on stratospheric chemistry and may give some information about the stratospheric hydroxyl concentration as well. We have determined the total column amount of HCl and HF above 12 km by measuring infrared absorption spectra with a high‐resolution Fourier transform spectrometer flown on a jet aircraft. The HCl column varies from 0.7×1015 molecules‐cm2 near the equator to 2.7×1015 molecules‐cm2 at 70°N; the HF column is about a factor of 5 lower. The HCl: HF ratio is almost independent of latitude, and neither constituent shows substantial seasonal or diurnal variation. At mid‐latitudes the data from 1978 to 1982 show an annual increase of 5% per year for HCl and 12% per year for HF.
On the absence of self‐oscillatory behavior in some zero‐dimensional climate models
Authors: Watts Robert G.
Published: February 2008

The autooscillatory behavior of some zero‐dimensional energy balance models stems directly from a misinterpretation of the Sellers parameterization of the variations of albedo with temperature. When a globally averaged value of the Sellers albedo is used, these models do not exhibit autooscillation.
Charge separation during rupture of small water drops in transient flows: Shock tube measurements and applications to lightning
Authors: Dreyfuss D. , Temkin S.
Published: February 2008

Charge separation during the rupture of small (1–2 mm) drops in the flow behind a shock wave was measured in a laboratory shock tube. The results are consistent with charge separation results measured for larger drops in steady airflows. Such charge separation could account for the lightning observed near volcanoes and above‐ground thermonuclear explosions. A charge regeneration also occurs in common thunderstorms due to thunder‐induced drop fragmentation, but this effect probably gives only a minor contribution to the charge distribution in a thundercloud.
NO3 and NO2 in the mid‐Pacific troposphere
Authors: Noxon J. F.
Published: February 2008

Spectroscopic measurements from Mauna Loa, Hawaii, yield mixing ratios for NO3 and NO2 at night of ∼0.3 and ∼30 ppt, respectively, at 3 km altitude in the free troposphere. The mixing ratio of NO2 in November is close to that measured earlier in June, and no significant seasonal change is apparent. The mixing ratio of NO3 is far below that expected, implying the existence of a scavenger for NO3; the scavenging rate (∼10−3 s−1) is close to that found earlier in the Colorado mountains. While the scavenger remains unidentified, it appears to be a well‐mixed and long‐lived atmospheric component. It is not known whether the scavenger acts as a sink for NOx or whether it merely sequesters it until the following day.
The non‐Gaussian joint probability density function of slope and elevation for a nonlinear gravity wave field
Authors: Huang Norden E. , Long Steven R. , Bliven Larry F. , Tung Chi‐Chao
Published: February 2008

On the basis of the mapping method developed by Huang et al. (1983), an analytic expression for the non‐Gaussian joint probability density function of slope and elevation for nonlinear gravity waves is derived. Various conditional and marginal density functions are also obtained through the joint density function. The analytic results are compared with a series of carefully controlled laboratory observations, and good agreement is noted. Furthermore, the laboratory wind wave field observations indicate that the capillary or capillary‐gravity waves may not be the dominant components in determining the total roughness of the wave field. Thus, the analytic results, though derived specifically for the gravity waves, may have more general applications.
An upper ocean current jet and internal waves in a Gulf Stream warm core ring
Authors: Joyce T. M. , Stalcup M. C.
Published: February 2008

On June 22, 1982, the R/V Endeavor, while participating in a multi‐ship study of a warm core ring 82B, encountered a strong front in the core of the ring. The vessel was headed on a radial section outward from ring center while a CTD was repeatedly raised and lowered between 10 and 300 m. Current profiles in the upper 100 m were obtained continuously with a Doppler acoustic profiling system. Above the shallow 45 m seasonal thermocline, a current jet of 4 km width was encountered having a central core of relatively light water and a maximum current of 1.1 m/s. This jet was both highly nonlinear and totally unexpected. A high frequency packet of directional internal waves was acoustically observed in the seasonal thermocline at the outer edge of the jet. Vertical velocities were large enough (6 cm/s) as to be directly observable in the Doppler returns. The waves were propagating from the northeast, parallel to the ship track, and orthogonal to the jet toward the center of the warm core ring. While a nonlinear, centrifugal term was required for the force balance of the jet, the high‐frequency internal wave packet could be explained with linear, gravest‐mode wave dynamics.
Horizontal Variability of temperature microstructure at the base of a mixed layer during MILE
Authors: Washburn Libe , Gibson Carl H.
Published: February 2008

Horizontal observations of temperature microstructure made during the Mixed Layer Experiment (MILE) show that the distribution of mixing activity in the seasonal thermocline at the base of the surface mixed layer was highly intermittent in horizontal planes. The horizontal extent of the observed microstructure patches was usually less than 10 m. The patches tended to occur in groups extending over distances of a few hundred meters, although some were isolated. Many patches of temperature microstructure activity occurred at density fronts separating regions of strong but opposite horizontal temperature‐salinity (T‐S) gradients. The sequence of horizontally averaged T‐S values form a looping pattern on a T‐S diagram which suggests that horizontal stirring processes are a source of microstructure generation. Spatial averages of the Cox number 〈(∇T)2〉/〈∇T〉2 and χ, the temperature variance dissipation rate, are determined by very small ractions of the record lengths, usually less than 5%. The distribution of χ was found to be approximately lognormal with variance of log10 χ of about 1.0, mean of 1.1×10−6 °C2/s, and mode 3.9×10−10 °C2/s. Good agreement was found with X values measured by dropsondes during MILE after accounting for the strong intermittency.
Application of a simple numerical wave prediction model to Lake Erie
Authors: Schwab David J. , Bennett John R. , Liu Paul C. , Donelan Mark A.
Published: February 2008

A parametric dynamical wave prediction model has been adapted and tested against semianalytic empirical results for steady conditions in a circular basin and extensive fiel measurements of wave height, period, and direction. The adapted numerical model accurately predicts the directional spreading of waves for uniform steady wind that Donelan (1980) had predicted analytically for fetch‐limited waves. When the model was applied to the central basin of Lake Erie and the results compared to observations of wave height and period (at two points in the lake) and direction (at one point), results for wave height and direction estimates were excellent compared to measurements at a research tower off the southern shore, but computed wave heights were lower than observed at a weather buoy in the western part. The model somewhat underestimated wave periods at both places. Thus, with locally measured wind data as input, the model estimates wave height and direction well and wave period acceptably.
Arctic Ocean water mass balance from isotope data
Authors: Östlund H. Göte , Hut Gert
Published: February 2008

The distributions of the oxygen 18 and tritium isotopes, and of salinity, yield a residence time of 10 years for the surface and halocline waters of the Arctic Basin. We find a yearly net production of 0.59 m of sea ice and an input of 1.16 m of freshwater from continental river runoff, local precipitation, and Bering Strait salinity deficiency. Using the basin area value with these numbers gives long‐term average total net production and transport rates of 0.15 Sv of ice and 0.18 Sv of meteoric component, Bering Strait water not included. If, in addition, a reasonable depth profile of relative current velocity is assumed for the outflow, a yearly input of 2.8 Sv of Atlantic and Bering Strait water is needed to replenish the upper and halocline waters. These numbers should be good to ±20% and are multiyear averages. The isotope data clearly indicate that the Barents Sea is an inflow area for Atlantic water to the basin, but that net export of ice occurs there.
Universal similarity and the thickness of the viscous sublayer at the ocean floor
Authors: Chriss T. M. , Caldwell D. R.
Published: February 2008

Experiments conducted on the Oregon continental shelf in June 1979 indicate that the boundary layer flow at the seafloor was hydrodynamically smooth. Fine‐resolution velocity profiles are used to test the assumption that the flow behaved like a universally similar, neutrally buoyant flow over a smooth wall. The non‐dimensional thickness of the viscous sublayer is far more variable than has been observed in laboratory studies over perfectly smooth walls. This variability may conceivably be related to upstream changes of surface roughness or to the presence of distributed roughness elements. Laboratory results indicate that the near‐bed flow adjusts extremely slowly to upstream roughness changes and suggests that flow near the sublayer in the ocean may be influenced by roughness changes as far as tens of meters upstream.
Coastal flows driven by a local density flux
Authors: Ikeda Motoyoshi
Published: February 2008

A two‐layer model with a rigid lid and a flat bottom on an f plane is employed to study a flow field driven by a density flux through the sea surface or the coast; for example, freshwater discharged from a river. The negative (positive) density flux into the upper layer is represented by the water beneath (over) the interface changing from the lower (upper) layer to the upper (lower) layer, that is, entrainment of the lower (upper) layer by the upper (lower) layer. The subinertial flow pattern constrained by the coast has two components: one is a baroclinic eddy nearby that matches the entrainment region, and the other is a forced, internal Kelvin wave along the appropriate half of the coast.
Ocean life cycles and the atmospheric CO2 content
Authors: Peng Tsung‐Hung , Broecker Wallace S.
Published: February 2008

The possibility that changes in the ocean's Redfield ratios, in the ocean's plant productivity, or in the extent to which organic material is recycled within the ocean have significantly altered the atmosphere's CO2 content over the past century is examined. Models show that the magnitudes of the alterations in these processes necessary to produce significant CO2 changes are unreasonably large. For those who do not wish to accept this theoretical approach, we offer a means to directly monitor the impacts of life cycle changes. It involves determining temporal trends in the dissolved O2, NO3, and PO4 contents of thermocline waters. While surveys carried out in 1972 (GEOSECS) and in 1981 (Transient Tracers in the Ocean) reveal no significant trend for the thermocline of the North Atlantic over this 9‐year period, a longer period of observation will be necessary before firm limits can be placed through this observational approach.
Physical properties of seawater: A new salinity scale and equation of state for seawater
Authors: Fofonoff N. P.
Published: February 2008

Developments leading to the new practical salinity scale and equation of state for seawater, introduced by the Joint Panel on Oceanographic Tables and Standards (JPOTS), are reviewed. The laboratory measurements used to construct the new empirical formulas for converting conductivity ratios to salinity and for estimating seawater density from salinity, temperature, and pressure were made on samples of standard seawater to minimize the effects of compositional variations. Measured densities were fitted with a standard deviation of 0.0036 kg/m3 at atmospheric pressure and 0.009 kg/m3 over the oceanic pressure range. Natural seawater densities can differ from computed density by as much as 0.05 kg/m3 because of variations in the composition of dissolved salts that are not reflected equivalently in measured conductivity ratios. Differences from the previous Knudsen‐Ekman equation of state are also of comparable magnitude. Values of specific volume anomaly for geopotential anomaly computations for estimation of geostrophic currents and transport are not significantly modified. Algorithms adopted by the JPOTS for computing adiabatic lapse rate and potential temperature are compared with formulas derived from the new equation of state. Potential temperatures agree within 2×10−3°C over the oceanic range of temperature and pressure at salinity of 35.
A note on the momentum transfer from wind to waves
Authors: Mitsuyasu H.
Published: February 2008

Momentum balance in the air‐sea boundary process is discussed on the basis of a recent study (Mitsuyasu and Honda, 1982). It is shown that the momentum transferred from wind to water surface goes largely into water waves when the steepness of the waves is large. For wind‐generated waves, however, much of the momentum transferred from wind to waves is lost by wave breaking, and only a small amount is advected by the wind waves.
Theory of synthetic aperture radar ocean imaging: A MARSEN view
Authors: Hasselmann K. , Raney R. K. , Plant W. J. , Alpers W. , Shuchman R. A. , Lyzenga D. R. , Rufenach C. L. , Tucker M. J.
Published: February 2008

This paper reviews basic synthetic aperture radar (SAR) theory of ocean wave imaging mechanisms, using both known work and recent experimental and theoretical results from the Marine Remote Sensing (MARSEN) Experiment. Several viewpoints that have contributed to the field are drawn together in a general analysis of the backscatter statistics of a moving sea surface. A common focus for different scattering models is provided by the mean image impulse response function, which is shown to be identical to the (spatially varying) frequency variance spectrum of the local complex reflectivity coefficient. From the analysis has emerged a more complete view of the SAR imaging phenomenon than has been previously available. A new, generalized imaging model is proposed.
Temporal variations of the microwave signatures of sea ice during the late spring and early summer near Mould Bay NWT
Authors: Grenfell T. C. , Lohanick A. W.
Published: February 2008

A series of surface‐based measurements of microwave brightness temperatures and accompanying ice characteristics have been made on first‐year and multiyear sea ice in the Canadian archipelago and in the southeastern Beaufort Sea during the late spring and early summer of 1982. Radiometer data taken at frequencies of 10, 18.7, and 37 GHz show the transition from conditions of snow‐covered ice from the onset of snow melt through to full summer melt conditions. Initially, values of TB for multiyear ice were larger than for first‐year ice, but by the middle of the experiment this distinction disappeared. Drained surfaces often had emissivities above 0.95, but values dropped considerably lower during heavy melting events. The skewness of the distribution of TB appears to distinguish ice types further into the melt season. The standard deviation is not useful for ice type discrimination but is sensitive to the area covered by melt ponds. Microwave attenuation in various surface layers was found to range from 2 m−1 early in the experiment to >400 m−1 during full summer melt, indicating penetration depths from 250 to 2.5 mm, respectively.
On the wind‐driven variability of the flow through Bering Strait
Authors: Aagaard K. , Roach A. T. , Schumacher J. D.
Published: February 2008

Analysis of time series from 1981 to 1982 near Bering Strait shows the meridional wind component, the current, and the oceanic pressure gradient to be well correlated. We argue that because of the constraining coastal geometry, there are wind‐driven flow divergences which perturb the oceanic pressure field and account for most of the current variability. For example, northerly winds cause a pronounced set‐down of sea level southeast of Bering Strait, and if the winds are strong enough, they will reverse the mean slope downward to the north through the strait. Winds during 1976–1977 were also well correlated with the Bering Strait transport estimates of Coachman and Aagaard (1981), and we therefore use the calculated winds from 1946 to 1982 to examine the low‐frequency transport variability. There is a marked seasonal cycle, with summer transport about 50% greater than during winter. The long‐term mean transport is calculated as less than 0.6 Sv, which is much lower than earlier estimates. Abnormally large transports apparently occurred during a number of years from 1948 to 1967, but during the past 15 years, transports have tended to be considerably less, corresponding to the stronger northerly winds during these years. The interannual wind variability near Bering Strait, together with the corresponding variability in the transport through the strait, is in fact part of the large‐scale variability of the atmospheric circulation over the North Pacific and its oceanic effects.
Gulf Stream warm‐core ring collection: An introduction
Authors: Joyce Terrence M.
Published: February 2008

The collection of papers that follows evolved out of presentations given at a warm‐core rings workshop at the Alton Jones Conference Center, University of Rhode Island, in August 1984. At that time it became clear that a number of investigators in the Warm‐Core Rings Program had reached a stage where they were completing the analysis of their individual data sets and models. Some of these studies were interrelated, and others were not. Our aim in collecting these investigations is not to present an integrated synthesis of Gulf Stream warm‐core rings but rather to provide a forum where some of our initial results can be focused.
Thermohaline intrusions in the frontal zones of a warm‐core ring observed by Batfish
Authors: Tang C. L. , Bennett A. S. , Lawrence D. J.
Published: February 2008

Hydrographic data collected with a towed, depth‐cycling instrument (Batfish) in the frontal regions of warm‐core ring 82H during and immediately after its formation were analyzed to study small‐scale structure and processes. The frontal and slope water regions are characterized by a complex water‐mass structure resulting from mixing of the shelf, the slope, and the Sargasso Sea waters. Thermohaline intrusions along constant density surfaces are frequently observed. Two forms of thermohaline intrusions are studied in detail: subsurface tonguelike intrusions and cold filaments. A subsurface tongue of shelf water origin was found in the slope water region outside the frontal zone at 70‐m depth. It had a width of 4 km, a thickness of 20 m, and a length of at least 40 km, and moved in a southeast direction toward the front. Alongside the subsurface tongue, a cold filament 10 km wide, extending from the surface to 120‐m depth, was observed. As the subsurface tongue and the filament moved toward the frontal zone, their orientation became more and more aligned with the front. When they reached the front, the strong frontal current carried them downstream and hence prevented further intrusion into the ring. Mixing in the form of interleaving then became the most important process for cross‐front mixing. Interleaving occurs along the side walls of the subsurface tongue and filament, with more intense interleaving associated with stronger intrusions. This suggests a double‐diffusive generation mechanism of the interleaving.
Comparisons between a continuous 3‐year current‐meter observation at the sill of the Yucatan Strait, satellite measurements of Gulf Loop Current area, and regional sea level
Authors: Maul George A. , Mayer Dennis A. , Baig Stephen R.
Published: February 2008

From October 1977 through November 1980 a current‐meter mooring was maintained in the Yucatan Strait. The meter was moored halfway between Mexico and Cuba, 145 m above the sill or in 1895 m of water. Motions of low frequency (<14−1 cycles/day) are oriented approximately parallel to the isobaths, 021°–030° true. Net drift for 3 years is to the SSW at an average velocity of 1.8 cm/s. Sustained southward flows at intervals of 8 months, which persisted for several months each, have average velocities of 5 cm/s, with randomly spaced bursts as high as 15 cm/s. Energy in subtidal frequency bands has significant peaks near 38−1 and 19−1 cycles/day, with a broad band of energy between 300−1 and 200−1 cycles/day. The latter peak is consistent with the approximately 8‐month interval between the southward flow events. Comparison with weekly areal coverage of the Gulf Loop Current from Geostationary Operational Environmental Satellite infrared observations shows little covariation, except that 8 months is typical of some anticyclonic eddy generation. There is little coherence of sill depth velocities with Naples sea level at subtidal frequencies, but with Miami there is coherence at several frequencies, notably 38−1 and 19−1 cycles/day. In the higher frequencies, the principal tidal motions are diurnal and are oriented somewhat across the isobaths toward the northwest, 346°–349° true, with counterrotating O1 and K1 constituents. No semidiurnal, inertial, or fortnightly energy is observed above the background continuum.
Carbon tetrachloride, tetrachloroethylene, 1,1,1‐trichloroethane and bromoform in Arctic seawater
Authors: Fogelqvist Elisabet
Published: February 2008

The concentrations of carbon tetrachloride, tetrachloroethylene. 1,1,1‐trichloroethane, and bromoform have been determined for Arctic seawater in the Svalbard area in August and September 1980 by a pentane extraction of the seawater followed by glass capillary gas chromatographic separation and electron capture detection. The vertical distributions in a transection across Fram Strait show an inflow of 50 tons/year of carbon tetrachloride, 46 tons/year of tetrachloroethylene, and 114 tons/year of 1,1,1‐trichloroethane due to contamination of Atlantic water in the industrial latitudes, and the outflow through the same transection 50, 60, and 129 tons/year, respectively. The uncertainties in these figures are estimated to 50%. Bromoform has a biogenic source in the belts of benthic algae growing in the coastal waters of Svalbard. The mean concentrations for open surface waters were 0.83 (s = 0.17) ng/L, 0.68 (s = 0.23) ng/L, 2.5 (s = 1.8) ng/L, and 9.8 (s = 4.0) ng/L for carbon tetrachloride, tetrachloroethylene, 1,1,1‐trichloroethane, and bromoform, respectively. The anthropogenic substances, carbon tetrachloride, tetrachloroethylene, and 1,1,1‐trichloroethane, show an undersaturation in the surface water compared with atmospheric northern hemisphere concentrations, which is why the Arctic seawater is thought to act as a sink for atmospheric halocarbons from anthropogenic sources. The biogenic production of bromoform causes an oversaturation in open sea surface waters when compared with the atmospheric background, which is why bromoform is supposed to be a source of atmospheric bromine.
Sea surface temperature: Observations from geostationary satellites
Authors: Bates John J. , Smith William L.
Published: February 2008

A procedure is developed for estimating sea surface temperatures (SST) from multispectral image data acquired from the VISSR atmospheric sounder (VAS) on the geostationary GOES satellites. Theoretical regression equations for two and three infrared window channels are empirically tuned by using clear field of view satellite radiances matched with reports of SST from NOAA fixed environmental buoys from 1982. The empirical regression equations are then used to produce daily regional analyses of SST. The daily analyses are used to study the response of SST's to the passage of Hurricane Alicia (1983) and Hurricane Debbie (1982) and are also used as a first guess surface temperature in the retrieval of atmospheric temperature and moisture profiles over the oceanic regions. Monthly mean SST's for the western North Atlantic and the eastern equatorial Pacific during March and July 1982 were produced for use in the NASA/JPL SST intercomparison workshop series. Workshop results showed VAS SST's have a scatter of 0.8°–1.0°C and a slight warm bias with respect to the other measurements of SST. Subsequently, a second set of VAS/ buoy matches collected during 1983 and 1984 was used to produce a set of bias corrected regression relations for VAS.