bluuebunny/crossref_metadata_2025 huggingface dataset:
Sound speed structure across an anticyclonic eddy and the Gulf Stream north wall
Authors: Fenner Don F.
Published: February 2008

During a Naval exercise in November 1975, R/V Chain ran a line of expendable bathythermographs (XBT's) three times across the edge of a warm anticyclonic Gulf Stream eddy (i.e., across the eddy front). The first two lines were 200 km long, spaced about 24 hours apart, and also extended across the Gulf Stream north wall. The third line was 90 km long and occupied nearly 10 days later. Sound speeds were calculated by using the equation of Wilson (1960) from XBT temperatures and a salinity field derived from exercise data. Detailed sound speed analyses clearly delineated the eddy edge and indicated that anticyclonic eddy fronts are among the strongest fronts found in the North Atlantic Ocean. Comparison of the three lines showed that the eddy front advanced to the west at an average rate of 9 km/day (0.2 kn) over the course of the 3‐week exercise. A period of rapid frontal migration followed and apparently was caused by high winds from a major storm halfway through the exercise. Preliminary analysis of acoustic data indicates signal enhancements of several decibels for a source outside the eddy and a receiver within the eddy.
Wind effects on surface to bottom fronts
Authors: Csanady G. T.
Published: February 2008

In nearshore regions, water of reduced density is frequently present owing to freshwater influx or spring heating. Under some circumstances, light nearshore water is confined to one side of a density front, extending from surface to bottom, and is called ‘spring thermocline’ or ‘shelf edge front.’ The shape and permanency of this front are affected by wind stress, which may interfere with the momentum balance in a direction parallel to the front and cause geostrophic adjustment motions normal to the front. A simple geostrophic adjustment theory elucidates some of the more important effects of wind on such fronts. Winds opposing the geostrophic flow above the inclined front tend to flatten its shape and eventually destroy the front, sometimes causing the formation of a surface ‘lens’ or ‘bubble.’ Comparison with observations from Lake Ontario and from the New England continental shelves shows that the theory gives a realistic first‐order description of frontal behavior.
Cabbeling at thermohaline fronts
Authors: Bowman Malcolm J. , Okubo Akira
Published: February 2008

A linear model with cabbeling dynamics is developed for a nonrotating, unstratified ocean and applied to observations of three medium‐ to large‐scale oceanic thermohaline (density balanced) fronts. The ability of the predicted cabbeling sinking and surface convergence rates to maintain a steady front against diffusion depends critically on the assumed values of horizontal and vertical eddy viscosities. There is good theoretical evidence for the existence of small‐scale (1 km), weak (surface currents 0.1 cm s−1) cabbeling fronts; however, the intensity and stability of such fronts will depend critically on the scale dependent behavior of dissipation processes.
A new technique for measuring tidal currents by using a two‐site HF Doppler radar system
Authors: Frisch A. S. , Weber B. L.
Published: February 2008

We have measured surface currents by using a newly developed high‐frequency (HF) Doppler radar technique. The system was operated in lower Cook Inlet, Alaska, in July 1977. During one particular day, July 13, we analyzed the radar data collected every 30 min for 24 hours. By least squares fitting these data to two of the dominant tidal periods, 12.31 and 24.6 hours, we determined the spatial distribution of the tidal currents for each of these two periods. In addition, we determined the spatial distribution of the mean surface currents for this 24‐hour period. Our analysis of this data shows that near Kachemak Bay there is a distinct difference of the east‐west component of tidal flow in comparison with regions further from Kachemak. In addition, we observed longer period components for which we cannot determine the period. These components exhibited gyrelike spatial patterns. Our results demonstrate the use of HF radar techniques for resolving spatial and temporal currents which affect the nearshore environment.
Local and shoaled comparisons of sea surface elevations, pressures, and velocities
Authors: Guza R. T. , Thornton Edward B.
Published: February 2008

Sea surface elevations, or pressures, and velocities were measured at closely spaced (wavelength or less) locations in a line extending from 10‐m depth to inside the surf zone at Torrey Pines Beach, San Diego, California. Intercomparisons of local pressure, velocity, and sea surface elevation spectra for the wind wave frequencies (0.05–0.3 Hz) were made by using linear wave theory. Errors in both total variance and energy density in a particular frequency band are less than 20% both inside and outside the surf zone, except in the immediate vicinity of the breakpoint, where larger disparities are observed. Surface elevation spectra calculated at 10 m were shoaled by using linear wave theory. The total variance of stations between 10‐ and 3‐m depth are typically predicted with less than 20% error, although harmonic amplification and other nonlinear effects can lead to significant errors in the prediction at particular frequency bands. Observations inside 3‐m depth significantly departed from the predictions of linear shoaling theory.
A factor analysis of elemental associations in the surface microlayer of Lake Michigan and its fluvial inputs
Authors: Mackin James E. , Owen Robert M. , Meyers Philip A.
Published: February 2008

Elemental concentrations in surface microlayer and subsurface water samples from Lake Michigan and from its major fluvial sources were subjected to separate R mode factor analyses to define the geochemical phases and mechanisms which influence the composition of the surface microlayer. The associations revealed by these analyses indicate that the composition of fluvial microlayers is controlled by localized factors related to the geology of individual drainage basins, while open lake microlayers are influenced by broad scale physiochemical interactions. Depletions of both dissolved and particulate phase constituents in fluvial microlayers are attributed to upward diffusion of ions in sediment pore fluids and resuspension of bottom sediments. Enrichments of these constituents in open lake microlayers are due to organic complexation, biological uptake, and bubble flotation of fine‐grained mineral particles.
Longshore sediment transport by tidal currents
Authors: Seymour R. J.
Published: February 2008

A mechanism for longshore sediment transport outside the surf zone is proposed on the basis of the variation in bottom stress under stationary waves produced by tidal depth changes. The variation in stress is in phase with the longshore component of tidal velocity and is shown to produce a net transport counter to the direction of the advance of the tide along the coast. An analytical model for predicting tidal transport is developed and is applied to measurements of tidal currents and waves near Oceanside, California, over a 3‐week period. The tidal transport rate decreases rapidly with depth, and the total net transport is shown to be a very small fraction of that anticipated from wave‐driven currents at that location.
A note on the seasonal transport on the Middle Atlantic Shelf
Authors: Bishop Joseph M.
Published: February 2008

A simple analytical model is proposed that adequately predicts both the mean summer and mean winter transport along the Middle Atlantic Shelf. The mean flow is modeled by using the steady Ekman and geostrophic equations driven by the mean wind stress, the mean cross‐shelf density gradient, and a variable longshore sea‐surface slope. It is shown that previous models, although consistent with this approach, might have to be refined to include longshore and seasonal variations in the longshore sea‐surface slope. Also, seasonal variations in mean wind stress and mean cross‐shelf density gradient are identified as key components in the description of flow dynamics. Calculated transports agree with the limited observations.
Investigation of sodium in the upper atmosphere
Authors: Yeringil Ilhami , Ögelman Hakki , Kiziloglu Nilgün
Published: February 2008

Upper atmospheric atomic sodium abundances have been measured near Ankara (39.9°N, 32.6°E), Turkey, from February 1976 to April 1977. The daytime absorption measurements were made with a Pepsios spectrometer using the solar radiation near the D2 line of sodium at 5890 Å. Seasonal and daily variations of the sodium abundance were examined. A seasonal variation appears to be present with maximum abundance values occurring near the end of February and minimum values occurring in April. No significant evidence was found for diurnal variations. However, there is some evidence for shorter‐period fluctuations with periods between 25 and 108 min. A model is proposed in which the atomic sodium has a cloudlike structure, and the parameters obtained in this way suggest that the ‘clouds’ have a mean column density of 1.5×109 atoms/cm2.
The damping of ocean surface waves by a monomolecular film measured by wave staffs and microwave radars
Authors: Hühnerfuss Heinrich , Alpers Werner , Jones W. Linwood , Lange Philipp A. , Richter Karl
Published: February 2008

The damping of ocean surface waves by a monomolecular oleyl alcohol film of about 1.5–3 km2 in area is measured in the North Sea by wave staffs, a coherent X band microwave scatterometer mounted on a sea‐based platform, and an incoherent Ku band microwave scatterometer carried by an aircraft under moderate wind conditions (wind speed u10 = 3.5–7.7 m s−1). The observed wave attenuation by the monomolecular surface film measured by a wave staff in the frequency band between 3.2 and 16 Hz is in the range of about 40–60%, with only a slight increase with frequency. From this result it can be predicted that slicks affect microwave backscattering similarly in the L band (λ0 ≈ 20 cm) as in the Ku and X bands (λ0 ≈ 2 cm). It is shown by additional wave tank experiments that a direct influence of oleyl alcohol surface films on wave damping is confined to frequencies f ≥ 2 Hz, but a further indirect effect of oleyl alcohol films on the damping of ocean waves in the frequency range between 0.12 and 0.7 Hz by modifying the wind input and wave‐wave interaction mechanisms is indicated from our results. A possible directional dependence of the wave‐damping effect caused by surface films is discussed.
Contamination of current records by mooring motion
Authors: Von Zweck Ortwin H. , Saunders Kim David
Published: February 2008

Mooring motion is shown to contaminate current measurements by (1) redistribution of energy in frequency, (2) wave number dependent attenuation, and (3) the linear superposition of mooring motion. Time dependent Doppler shifting redistributes spectral energy to higher and lower frequencies. Wave number attenuation is a function of the ratio of meter displacement to wave length. Neither type of contamination appears to be readily removable.
Field‐controlled ionic charging of ice crystals
Authors: Richards W. G. , Macafee A. W. , Iribarne J. V.
Published: February 2008

The charging curves and the saturation values of both charge and potential have been determined for six metal models with typical ice crystal shapes (bullet, columns, needle, plate, and dendrite) with different orientations in a unipolar ion current, in conditions that make the charging process field controlled. Metal spheres of several sizes were also used, as a reference. It was found that the theory of field‐controlled charging for spheres adequately describes the process for ice shapes, provided the variable (charge or potential) is multiplied by a factor depending on shape and orientation. Thus the saturation charge per unit cross section exposed to the ion current varied from 0.4 to 15 times that for a sphere, for the models used. The results are relevant to the formation of shielding layers at the upper level of thunderclouds. The measurements also provide estimates of a parameter (numerically equal to capacitance) that controls the rate of growth by sublimation.
The onset of the summer monsoon during the FGGE 1979 experiment off the East African coast: A comparison of wind data collected by different means
Authors: Schott Friedrich , Fernandez‐Partagas José
Published: February 2008

During FGGE 1979, from March to July, an extensive oceanographic experiment with ships and moored stations was carried out in the Somali Current. The development of the monsoon winds off Somalia during the time of that experiment is described in a comparative analysis of standard ship wind observations, moored buoy wind measurements, low‐level cloud winds, and winds from land stations. The onset 1979 is found to be of the multiple type, with northward winds off Somalia beginning around May 5 but dying down into early June; the real onset of sustained high winds starts around June 10. Cloud level wind observation numbers off Somalia decrease drastically with the monsoon onset because of lack of clouds over the quickly developing cold upwelling areas. An intercomparison of cloud level and ship winds for the period May 16 to July 6 at five offshore points shows good agreement in directions but reduction of ship wind speeds against cloud level winds off northern Somalia after the onset, which may be explained by the increased vertical wind shear due to high air stability over the upwelled water and by geostrophic shear due to the strong gradients of sea surface temperature. A comparison of 3‐day averages of buoy winds measured at 3‐m height 30 km offshore, but still inland from the ship lane, with ship winds for the period March 3 to June 10 showed good agreement in directions but lower buoy wind speeds, which could partly be due to sensor height difference and partly due to horizontal wind shear towards the coast. Coastal stations and wind buoys near the coast are found not to be good indicators of the monsoon onset further out in the open ocean.
An inertial subrange in microstructure spectra
Authors: Newberger P. A. , Caldwell D. R.
Published: February 2008

An inertial subrange was found in spectra calculated from vertical profiles of temperature gradient recorded in the bottom boundary layer of the Oregon shelf. Spectra were calculated for 53‐cm vertical segments. An ensemble average of those spectra that were fully resolved and had high Cox number was compared to the universal form. Good agreement was found with the Batchelor form. The high wave number end of the inertial range was resolved. A relationship between the Kolmogorov constant for temperature, β, and the Batchelor constant, q, was established, βq−2/3 = 0.172 (±0.012). If β = 0.5, as determined from atmospheric data, then q = 4.95 (4.28 < q < 6.65) and the transition from the inertial to the viscous‐convective range occurs at a wave number k = 0.035 kK (0.021 < k/kK < 0.043) where kK is the Kolmogorov wave number.
Plane waves in a viscoelastic floating ice sheet
Authors: Bates Howard F. , Shapiro Lewis H.
Published: February 2008

The correspondence principle of viscoelasticity is applied to obtain the plane‐wave impulse response of a laterally compressed viscoelastic plate floating on a perfect liquid. The system is analyzed as a wave guide having a small damping factor. A four‐parameter linear viscoelastic model is used to simulate the the characteristics of a sheet of floating ice. Values appropriate for small deflections in sea ice are used to produce illustrative examples of the displacement and the vertical loading stress caused by the bending produced in an ice sheet by plane waves arising from a unit line force moving uniformly across the sheet. Because the displacement of the viscoelastic plate remains finite, this technique provides a means for making engineering estimates of the stress produced by waves at the critical frequency.
The thinness of oceanic temperature gradients
Authors: Caldwell D. R. , Chriss T. M. , Newberger P. A. , Dillon T. M.
Published: February 2008

A test of the scaling of the extent of the thinnest vertical temperature gradients, in the near‐bottom boundary layer on the Oregon shelf, shows that the Batchelor wave number determines the cutoff wave number in vertical temperature gradient spectra. In combination with previous results, in other words, this test shows that the smallest scale at which significant temperature variance due to turbulence exists at any given point in the ocean is determined by the Batchelor scale, (vD2/ε)l/4, v being the kinematic viscosity, D the thermal diffusivity, and ε the kinetic energy dissipation per unit mass. Stress measurements in the viscous sublayer provide estimates of ε.
On the role of photo‐induced solution reactions in determining atmospheric aerosol concentrations
Authors: Middleton Paulette
Published: February 2008

The role of photo‐induced solution reactions in determining atmospheric aerosol concentrations is discussed and is investigated with theoretical estimates. The main photo‐induced solution reaction considered is the conversion of dissolved O3 into H2O2 which can then react with dissolved SO2 and NO2 to form sulfate and nitrate. The rate of this reaction is compared to the rate of H2O2 formation in solution from diffusion and absorption of H2O2 gas to the aerosol surface. The influences of H2O2 concentration and aerosol size on the relative rates are investigated. It is found that the photo‐induced solution reaction rate is much lower than the gas diffusion rate but becomes more competitive as particle size increases.
Carbon dioxide measurements in tropical East African biomes
Authors: Schnell R. C. , Odh S.‐A. , Njau L. N.
Published: February 2008

From January 1977 through May 1978 atmospheric CO2 concentrations were measured hourly and/or continuously at bimonthly intervals over periods varying from 5 to 8 days at 10 different locations in Kenya, East Africa. During each of these periods, at least two, and in some cases five, vertical profile measurements of CO2 concentrations were conducted above different biomes. A large diurnal CO2 periodicity was observed over land, with daytime drawdowns to 322 ppm and nighttime buildups to more than 400 ppm observed in savannah regions. In and around tropical rain forests, drawdowns to 310 ppm and buildups to more than 400 ppm were regularly observed. On the higher reaches of Mount Kenya, the diurnal CO2 cycle was considerably reduced in amplitude, with variations in the range of 2–6 ppm throughout the 16‐month study period. On sunny days, the drawdown of CO2 was measurable to heights of at least 4000 m above ground level. Other CO2 concentration measurements in air over the Indian Ocean (to distances of up to 450 km upwind of the coast) produced fairly consistent concentrations of about 328.5 ppm which did not fluctuate diurnally. The weekly mean CO2 concentrations over Kenya appear to have a bimodal structure, with minima occurring in July and January. On the basis of the data collected during the study it appears likely that regular observations at a high‐altitude station on Mount Kenya, either with flask sampling or continuous analyzer measurements, are likely to yield data useful for estimates of CO2 concentration backgrounds and trends. Also, there is strong evidence that Mount Kenya would be a good location to measure large‐scale interhemispheric CO2 exchanges and provide a unique base from which to study the effects of the tropical biome on biogeochemical phenomena.
Field observations of surf beat: 1. Progressive edge waves
Authors: Huntley D. A. , Guza R. T. , Thornton E. B.
Published: February 2008

Nineteen biaxial electromagnetic current meters have been used to determine the longshore and on/offshore structure of currents at surf beat periods (1–4 min). The sensors formed two linear arrays, a long‐shore array within the surf zone and an on/offshore array stretching from the shoreline to well beyond the breaker line. Analysis of the longshore current components yields a clear picture of progressive low‐mode edge waves, with frequency‐wave number dispersion relations which are in remarkably good agreement with predictions. Some separation of edge wave modes is found, with mode zero energy dominating in the frequency band 0.006 and 0.011 Hz and mode one between 0.015 and 0.025 Hz. On/offshore currents present a rather different picture which, while not inconsistent with the longshore currents, suggests that other sources of energy are also important to the on/offshore currents. These include standing edge waves probably formed by reflections at nearby Scripps Canyon, and motions which are nonresonantly forced by incoming wave groups.
The extended velocity potential versus stokes wave representation
Authors: Lambrakos K. F.
Published: February 2008

The velocity potential for finite surface water waves is expressed in terms of a double Fourier series expansion in the wave number and frequency. The Fourier coefficients are calculated from a numerical fit to the boundary conditions at the wave surface. This expansion differs from the Stokes expansion in that for each frequency corresponds a set of harmonic waves of varied wave numbers instead of a single harmonic wave. This velocity potential permits interactions between wave harmonics and can describe single periodic waves that deform with propagation (LAMB waves) and their water particle kinematics. Stokes waves represent a special case of this larger class of deforming waves. For LAMB waves the energy in each harmonic component can transfer from the lower to the higher frequencies and vice versa, and the outward effect of this transfer is the modulation and demodulation of the waves. The changes in wave shape significantly affect the wave kinematics, and this is illustrated with a cosine wave. Also, the present solution for steep Stokes waves is shown to be of higher accuracy than the well‐known Stokes' V solution and in close agreement with other higher‐order Stokes wave procedures.
A note on some uses of θ‐S sections
Authors: Bruce J. G.
Published: February 2008

Isohalines plotted against temperature and horizontal distance along a hydrographic section can be used to observe changes in the T‐S or θ‐S relationship of water masses. By using this technique, eddies formed off the Somali coast during the southwest monsoon, or Gulf Stream eddies having their own individual T‐S characteristics, may be identified.
Balloon‐borne measurements of electrical conductivity, mobility, and the recombination coefficient
Authors: Rosen J. M. , Hofmann D. J.
Published: February 2008

Balloon‐borne measurements of the positive polar conductivity σ+ from near ground level to 35 km are presented. The data were obtained in conjunction with measurements of the ionization rate q and the positive ion density n+. These three parameters are used to calculate the average positive ion mobility profile and the effective recombination coefficient profile. Within the experimental accuracy of about ±10% the reduced mobility is constant with altitude at a value of about 1.5 × 10−4 m2 V−1 s−1. The recombination coefficient profile compares favorably to possible theoretical predictions, but there is some serious question as to whether the theoretical values can in fact be compared directly to the experimental results obtained here.
A study of the effectiveness of the ClX catalytic ozone loss mechanisms
Authors: Wuebbles D. J. , Chang J. S.
Published: February 2008

The importance of catalytic mechanisms involving chlorine species for destroying stratospheric ozone is now well recognized. In this study, we determine that there are at least four catalytic cycles of varying importance for analyzing potential odd oxygen destruction from chlorine species in the stratosphere. The relative efficiency of these cycles varies significantly with altitude. Since individual halocarbons release chlorine atoms over a wide range of different altitudes in the stratosphere, their impact on stratospheric ozone must be due to the combined effect of each of these cycles. Indeed, changes in the vertical ozone distribution for various halocarbon perturbations were found to differ significantly owing to differences in the altitude range of inorganic chlorine releases and to differences in relative catalytic efficiencies.
Carbon dioxide and climate: The effects of water transport in radiative‐convective models
Authors: Hummel John R. , Reck Ruth A.
Published: February 2008

Considerable attention is being focused on the possible climatic effects resulting from increases in the concentration of atmospheric carbon dioxide. In calculating CO2 influence on the thermal structure of the atmosphere, the role of clouds is critically important. Not only are the cloud properties, such as amount, numbers of clouds, altitudes, and optical properties important but also whether or not these properties are fixed or coupled to model temperatures. The transport of water vapor determines whether or not a region has clouds, the cloud properites, and the water vapor profiles appropriate for clear and cloudy skies. Results are presented of the change in surface temperature with changes in carbon dioxide content for two radiative‐convective models with three different cloud coverages. We used (1) the Manabe‐Wetherald radiative‐convective model in which three clouds with fixed pressures, thicknesses, and optical properties and a single water vapor profile are inputed and (2) the Hummel‐Kuhn model, which couples radiative heating, convection, and water vapor transport in order to calculate locations and thicknesses. The Hummel‐Kuhn model yields temperature increases for doubled CO2 larger than the Manabe‐Wetherald model for various assumed total cloud cover amounts. For assumed standard cloud cover amounts the Hummel‐Kuhn estimate is 20% larger than the Manabe‐Wetherald estimate. For reduced and enhanced cloud cover amounts the Hummel‐Kuhn estimates are 37% and 17% larger, respectively. The calculated cloud locations and thicknesses did not change in the calculations; therefore the increased sensitivity in the Hummel‐Kuhn model is due to the larger water vapor amounts in the Hummel‐Kuhn model and the added infrared absorption by the water vapor dimer.
Observations of ozone depletion associated with solar proton events
Authors: McPeters R. D. , Jackman C. H. , Stassinopoulos E. G.
Published: February 2008

Data from the backscattered ultraviolet instrument (BUV) on Nimbus 4 show depletion of ozone following solar proton events in January and September 1971 and in August 1972. The direct effect of high energy protons on the BUV instrument was determined by comparing nighttime BUV counting rates with particle data from IMP 6. The instrumental effects were then subtracted to allow accurate calculation of ozone profiles during the three events. The solar proton event of August 1972 was very large and produced an ozone depletion of 15% at 42 km that persisted for almost 30 days. This long recovery time indicates that NOx was produced in a quantity sufficient to alter the ozone chemistry. The two proton events in 1971 were of moderate size but produced ozone depletions of 10–30% at 50 km with a 36‐hour recovery time. The rapid recovery is consistent with the assumption that HOx was responsible for altering the ozone chemistry, but the magnitude of the observed depletion exceeds that predicted by our chemical models.
Calculations of lightning return stroke electric and magnetic fields above ground
Authors: Master M. J. , Uman M. A. , Lin Y. T. , Standler R. B.
Published: February 2008

The first detailed calculations of lightning return stroke electric and magnetic fields above ground are presented. Waveforms are given for altitudes from 0 to 10 km and ranges from 20 m to 10 km. These waveforms are computed using the model of Lin et al. (1980) and a modification of that model in which the initial current peak decays with height above ground. Both the original and the modified models result in accurate prediction of measured ground‐based fields. Return stroke field measurements above ground close to the stroke, with which the calculations could be compared, have not yet been made. Salient aspects of the calculated fields are discussed, including their use in calibrating airborne field measurements from simultaneous ground and airborne data.
Measurements of atmospheric turbidity and vertical mass loading of particulate matter in marine environments (Red Sea, Indian Ocean, and Somalian coast)
Authors: Tomasi Claudio , Prodi Franco
Published: February 2008

Measurements of direct solar radiation at two window wavelengths were performed with a portable Volz sun‐photometer (type III) during the scientific cruise from the Mediterranean to the Indian Ocean on the vessel Salernum (January and February 1979). From these data, evaluations of Ångström's parameters were obtained, describing the atmospheric turbidity conditions associated with the aerosol particle populations in the maritime areas of the Red Sea, Indian Ocean, and Somalian coast. The spectral exponent α was found to range mostly between 0.2 and 0.7 in coastal areas and between 0.3 and 0.9 in the ocean. The parameter β mostly varies from 0.10 to 0.35 in coastal areas and from 0.05 to 0.25 in the oceanic ones. Estimates of the vertical mass loading M of particulate matter were obtained by examining the particulate optical thicknesses in terms of extinction models based on realistic bimodal size distributions of particles. Relatively low values of M were found in the area of Bitter Lakes and Suez Gulf. The quantity M was found to increase gradually in the Red Sea, as the vessel was moving southward, and to reach rather high values around 80 μg cm−2 in the leg along the Somalian coast. In the ocean, M was found to range around 25 μg cm−2 for the most part owing to the sea salt component.
Effect of ashfall on snowmelt rate at paradise, Mount Rainier, Washington
Authors: Brown Bert E.
Published: February 2008

Snowpack data and temperature information in the form of degree‐day calculations are analyzed for Paradise, Mt. Rainier, for the weeks following the May 18, 1980, eruption of Mt. St. Helens. The figures are compared with similar computations for the preceding 25 years. The results show that the dark ash layer increased the snowmelt rate by some 40% over what would have been expected from ambient temperatures.
A potential‐flow model of turbulence caused by breaking surface waves
Authors: Thompson Rory O. R. Y.
Published: February 2008

A very simple model of the effect of breaking surface waves in the ocean, or grid stirring in laboratory experiments, is that of random forcing at the surface of a deep homogeneous fluid with linear, frictionless dynamics. The ‘turbulence’ is physically separated from the gravity waves by a ‘rigid lid’ approximation. The model predicts that the turbulent kinetic energy decreases as the inverse square of the depth, beyond a depth δ, which is the width of a typical wave burst (or a few grid intervals in the laboratory). The integral length scale is proportional to depth (again past δ), so the turbulent Reynolds number is independent of depth. The model nontrivially satisfies an equation previously interpreted as giving the flux of turbulent energy in grid‐stirring experiments. The measure of ‘inertial dissipation’ used there is thus called into question.
Influence of heat fluxes on self‐similarity of stress‐driven entraining flows
Authors: Kundu Pijush K.
Published: February 2008

The effect of surface heat flux on the possibility of self‐similar solutions in a wind‐driven turbulent layer penetrating into a stratified fluid has been examined. It has been found that approximately similar solutions are possible if the initial stratification is depth independent. Similarity requires t < tQ, where the ‘heating time scale’ tQ is typically a few days. A relation has been derived for the surface layer depth h(t) and compared with numerical calculations.
SEASAT altimeter height calibration
Authors: Kolenkiewicz Ronald , Martin Chreston F.
Published: February 2008

The SEASAT altimeter has been calibrated for height bias using four overflight passes of Bermuda that were supported by the Bermuda laser. The altimeter data was corrected for tides, by using recorded tide gage data; for propagation effects, by using meteorological data taken around the time of each pass; for acceleration lag; and for sea state bias, including both surface effects and instrumental effects. Altimeter data for each of the four passes was smoothed and extrapolated across the island. Interpolation between passes then produced an equivalent altimeter measurement to the geoid at the laser site, so that the altimeter bias could be estimated without the use of a geoid model. The estimated height bias was 0.0±0.07 m.
Tidal and geodetic observations for the SEASAT altimeter calibration experiment
Authors: Diamante John M. , Douglas Bruce C. , Porter David L. , Masterson Robert P.
Published: February 2008

A calibration experiment for the SEASAT radar altimeter was conducted in the Bermuda calibration area during September and October of 1978 by a group of Federal Government agencies, universities, and research organizations. As part of the SEASAT calibration activities, a tide gage was installed by the National Ocean Survey at an open coastal location on Bermuda to provide a determination of the instantaneous sea surface height during the SEASAT overflights of the island. The tide gage was geodetically tied to the laser tracking station on Bermuda, so that SEASAT's position relative to the sea surface could be determined independently and compared with the value provided by the altimeter measurements. The root sum square error in the determination of the vertical position of the laser, relative to the sea surface, has been estimated to be 4.0 cm exclusive of possible errors arising from the present lack of precise information on the elevation of the geoid at Bermuda.
General distribution of water masses within the eastern Caribbean Sea during the winter of 1972 and fall of 1973
Authors: Morrison John M. , Nowlin Worth D.
Published: February 2008

Quasi‐synoptic descriptions of the circulation and water mass distributions within the eastern Caribbean Sea are presented for winter 1972 and fall of 1973. Vertical sections of properties within these basins and along the axes of the major passages into this region, together with property distributions on isopycnal surfaces (chosen to be representative of the principal water masses), are used to describe the circulation. The flow paths of the various water masses into and out of the region are identified. The water masses identified within the eastern Caribbean Sea and their points of entrance into the region are as follows: Subtropical Underwater enters through the northern Lesser Antilles, 18°C Sargasso Sea Water enters through the passages of the Greater Antilles, Tropical Atlantic Central Water and Antarctic Intermediate Water enter through the southern Lesser Antilles, and North Atlantic Deep Water enters the Venezuelan Basin through Anegada‐Jungfern Passage and enters the Colombian Basin between Jamaica and Hispaniola. Water mass distributions and dynamic maps are used to compare and contrast the quasi‐synoptic current patterns present within the eastern Caribbean Sea during the winter of 1972 and fall of 1973. During both periods, a two‐stream westward current was observed in the Grenada Trough and Venezuelan Basin. Within the Colombian Basin, these streams combine to form one northwestward flow out of the region. The area where these streams combine is controlled by the intensity of a dynamic high located south of Hispaniola. The intensity of this high appears to be controlled by the curl of the local wind stress and tends to weaken during the fall when the wind stress curl reaches a minimum. Therefore ‘seasonal’ changes in the current pattern may actually be associated with seasonal changes in the atmospheric forcing. Geostrophic computations give a net westward transport for the Caribbean Current system of 29×106 m3 s−1 during both seasons. This net westward transport agrees quite well with transport estimates of flow into and out of this region by previous investigators.
Measurements of oceanic temperature microstructure using a small conductivity sensor
Authors: Washburn Libe , Gibson Carl H.
Published: February 2008

A small, high frequency response conductivity probe has been constructed and used at sea. Measurements were made from an instrument platform towed at 35 m depth in the seasonal thermocline at ocean station P during the 1977 Mixed Layer Experiment (MILE). The microconductivity probe consists of four parallel electrodes plated on one side of a 0.5 mm × 3 mm × 3 mm ceramic chip with the electrodes aligned in the direction of flow. Comparisons with a microbead thermistor signal show that the conductivity signal was dominated by temperature up to the maximum frequency response of the thermistor, about 25 Hz. Therefore, under the conditions of the experiment, the conductivity probe signal measured temperature, but to smaller scales and higher frequencies than the microbead thermistor. Conductivity gradient spectra peaked in regions of different microstructure activity at frequencies between 11 and 96 Hz corresponding to temperature diffusive cut‐off wavelengths between 16 and 1.85 cm. The estimated frequency response of the probe based on flushing of the conductivity cell volume is 700 Hz at the 1.78 m/s average towing speed during MILE. Spatial resolution of the probe appears to be adequate to resolve the smallest scale temperature gradients encountered during the experiment. Conductivity gradient spectral levels in some regions of microstructure activity were 10–1000 times larger than spectral levels of the noise.
Annual temperature fluctuations at the subtropical and subarctic fronts in the central North Pacific
Authors: Kang Yong Q. , Magaard Lorenz
Published: February 2008

We show that the transpacific expendable bathythermograph data of the North Pacific Experiment (NORPAX) contain annual temperature disturbances that propagate along the Subtropical (32°N) and Subarctic (42°N) fronts in the central North Pacific. We find these disturbances in the depth range 150–400 m. They propagate with phase speeds of between 10 and 20 cm s−1, and they reverse their direction of propagation with an annual cycle. We present a possible explanation of this phenomenon in terms of baroclinic Rossby waves in flow with vertical and lateral shear.
Rainfall patterns in the western United States
Authors: Vines R. G.
Published: February 2008

Rainfall figures from World Weather Records, for towns west of the Mississippi in the United States, have been subjected to filter analysis. Four filters have been used, and the rainfall patterns obtained suggest substantial coherence of the data throughout much of the entire area. The results agree well with earlier work of Mitchell, Stockton, and Meko, who have reported a relationship between the incidence of drought in the western United States and the double (ca. 22 year) sunspot cycle. However, an additional correlation with the (ca. 18 year) lunar cycle is also apparent, particularly on the west coast.
Studies on fallout debris from the recent Chinese test
Authors: Sadasivan S. , Mishra U. C.
Published: February 2008

Fission and activation products analysis of aircraft swipe samples by high‐resolution Ge(Li) spectrometry shows that the Chinese nuclear test of October 16, 1980, was a thermonuclear explosion carried out at low altitude. Most of the activity from this test appears to have fallen out in a year's time, as indicated by the activity ratios of selected fission products.
The effect of surface striations on the absorption of shortwave radiation
Authors: Carroll John J.
Published: February 2008

Most natural surfaces have shortwave albedos that are directly dependent on solar zenith angle. Strong dependences are well known for liquid water and have recently been reiterated for snow surfaces [Carroll and Fitch, 1981]. Many surfaces (e.g., water and dry snow) develop systematic macroscale ripple structures due to wind action (i.e., waves and sastrugi). This paper reports calculations of the effects of such structures on the solar radiation absorbed as a function of latitude, season, ripple amplitude, and ripple orientation. The ripples are represented as having triangular cross sections with the two upper faces tilted at angle B from the horizontal. The absorption of diffuse radiation is equal on all surfaces and computed by using the minimum surface albedo. Direct radiation absorbed is calculated by using the appropriate albedo for the solar zenith angle measured from each surface normal. Shadowing and interfacial reflections are included. The net solar radiation is normalized to a unit horizontal area (QNR) and compared to that calculated for a flat horizontal surface (QNH). Generally the ratio R ≡ QNH/QNR is slightly greater than one at high sun elevations and decreases with increasing tilt angle and increasing latitude. Minimum values of R (<0.5) are found for water at higher latitudes in winter. Model calculations indicate that surfaces with no albedo dependence on solar elevation also exhibit sensitivity to the presence of ripple structures.
Radium 228 as a tracer of basin wide processes in the abyssal ocean
Authors: Sarmiento J. L. , Rooth C. G. H. , Broecker W. S.
Published: February 2008

A simple model of isopycnal mixing in a circular basin is developed in order to examine the utility of the 5.75‐year half‐life tracer radium 228 for studying basin wide processes in the deep ocean. The model shows that it is possible to resolve diffusivities of ≤8×107 cm2 s−1 in a basin of ∼3000‐km diameter with profiles measured near the center and edge of the basin. A least squares fit of the model to four abyssal profiles measured during GEOSECS in the North American Basin gives an isopycnal diffusivity of 6×107 cm2 s−1.
Observations of eastward currents in the tropical South Atlantic Ocean: 1978–1980
Authors: Molinari Robert L.
Published: February 2008

Data from four cruises to the tropical South Atlantic Ocean are used to describe the current distribution at 25°W and 27.5°/28°W. Two distinct eastward‐flowing countercurrents separated by a branch of the westward‐flowing South Equatorial Current (SEC) were observed during all the cruises. The South Equatorial Undercurrent, located between 3°S and 5°S, has a subsurface velocity core, with maximum speeds of about 0.4 m/s. Geostrophic volume transports of the SEUC, from the surface to 1000 m, range from 5 to 23 Sv. Surface flow above the core of the SEUC can be to the east or west. The South Equatorial Countercurrent (SECC) is located typically between 7°S and 9°S. Although weaker than the SEUC with transports ranging from 3 to 7 Sv, the SECC also has a subsurface velocity core. Maximum speeds of 0.1 m/s are observed at about 275 m. Surface flow above the core of the SECC is typically to the east. Upper layer waters of the SECC are saltier and warmer than waters within similar density layers to the north.
Snow chemistry on James Ross Island (Antarctic Peninsula)
Authors: Aristarain Alberto J. , Delmas Robert J. , Briat Martine
Published: February 2008

More than 400 firn samples were collected at an altitude of 1660 m on the small ice sheet covering James Ross Island (northeastern coast of the Antarctic Peninsula). Chemical analysis of these samples provides information about the marine background aerosol composition in the area. The samples cover the years 1975–1979 (pit samples) and the last 15 years (firn core samples). Major impurities (Na, K, Ca, Al, H, SO4, and NO3) were determined by using flameless atomic absorption, neutron activation, acid titration, or ion chromatography. Aerosols are contributed mainly by the surrounding ocean; however, secondary aerosol deposition (H2SO4 and HNO3) is also important. All samples were found to be slightly acidic (pH generally in the range 5–6). Strong seasonal variations (maximum values in summer) are found in the H2SO4 deposition. A photochemical mechanism is proposed to explain the local production of H2SO4 from gaseous marine sulfur compounds. From these results, a yearly deposition of ∼0.13 Tg of H2SO4 is calculated for the entire Antarctic continent.
On the radiocarbon record in banded corals: Exchange parameters and net transport of 14CO2 between atmosphere and surface ocean
Authors: Druffel Ellen M. , Suess Hans E.
Published: February 2008

We have made radiocarbon measurements of banded hermatypic corals from Florida, Belize, and the Galapagos Islands. Interpretation is presented here of these previously reported results. These measurements represent the 14C/12C ratios in dissolved inorganic carbon (DIOC) in the surface ocean waters of the Gulf Stream and the Peru Current at the time of coral ring formation. A depletion in radiocarbon concentration was observed in coral rings that grew from A.D. 1900–1952. It was caused by dilution of existing 14C levels with dead CO2 from fossil fuel burning (the Suess effect, or Se). The observed depletion of radiocarbon was greater in corals from the Gulf Stream (−11‰) than in corals from the Peru Current (−6‰). A similar trend was observed in the distribution of bomb‐produced 14C in corals that had grown during the years following A.D. 1952. The concentration of bomb‐produced radiocarbon was much higher in corals from temperate regions (Florida, Belize, Hawaiian Islands) than in corals from tropical regions (Galapagos Islands and Canton Island). A linear relationship appears to exist between the preanthropogenic Δ14C values and the Se values measured in the individual corals, because the 14C in corals is derived from two different carbon reservoirs: (1) the atmosphere and (2) the subsurface ocean. A linear relationship is also observed between the preanthropogenic Δ14C values and the concentration of bomb‐produced 14C in the individual corals during A.D. 1973. The apparent radiocarbon ages of the surface waters in temperate and tropical oceans during the preanthropogenic period range from about 280 to 520 years B.P. (−40 to −69‰). At all investigated locations, it is likely that waters at subsurface depths have the same apparent radiocarbon age of about 670 years B.P. From the change of oceanic Δ14C in the surface ocean during post‐bomb times, the approximate annual rate of net input of 14CO2 to the ocean waters is calculated to be about 8% of the prevailing 14C difference between atmosphere and ocean. From this input and from preanthropogenic Δ14C values found at each location, it can be seen that vertical mixing of water in the Peru Current is about 3 times greater than that in the Gulf Stream.
Sampling strategy to obtain data used in models of global annual CO2 increase and global carbon cycle
Authors: Gillette Dale A. , Hanson Kirby J.
Published: February 2008

Simple models were constructed to assess with somewhat limited CO2 data the effects of both frequency of sampling and spatial distribution of sampling locations on the variance of estimates of interest to the global carbon cycle. The CO2 data for use in these models were obtained from seven air flask sampling locations, globally distributed in latitude but restricted to the longitude sector 80°W to 170°W, during the period 1977–1979. The results of analysis with these models show (1) that locations north of 30°N are quite important in possibly providing information on carbon cycle exchange processes and that (2) improved sampling techniques including greater sampling frequency would be desirable for sampling locations in the southern hemisphere.