bluuebunny/crossref_metadata_2025 huggingface dataset:
Eddies, islands, and mixing
Authors: Hogg Nelson G. , Katz Eli J. , Sanford Thomas B.
Published: February 2008

As part of a field study of the relation between fine scale and large‐scale variations of water properties in the western North Atlantic, the waters in the vicinity of Bermuda were investigated in detail. Previous work in the area had revealed regions of intense temperature fine structure confined to the sides of the island. Generally quieter levels of activity elsewhere in the midocean have suggested that significant mixing might only occur at the solid and fluid boundaries of the ocean. During the course of our investigation, two Gulf Stream rings were found in the vicinity of the island. The exchange of water between them caused three regions of strong alongshore flow. In these three areas we find elevated levels of temperature fine structure in the upper 800 m as measured by the variance in the temperature gradient normalized by the square of the mean temperature gradient over the interval. The normalized temperature variances on small scales (0.2–1 m) are most energetic in patches tightly bound to the island sides, whereas the fine structure on larger scales (5–25 m) is also energetic away from the island in a region of outflow. Velocity profiles show that vertical scales shorten as one approaches the island, and the energy increases in the counterclockwise component. There is no correlation evident between the shear measurements of the internal wave field and the intensity of the fine structure. Possible mechanisms for the production of fine structure are explored within the context of these observations.
Measurements of energy dissipation adjacent to an island
Authors: Osborn T. R.
Published: February 2008

Measurements of velocity shear microstructure were taken March 3–7, 1975, adjacent to the island of Santa Maria in the Azores. From the data it is possible to estimate the energy dissipation over 5‐m vertical intervals. Measurements within 5 km of the island show regions of high dissipation (up to 10−3 W/m3) as much as 45 m thick at the base of the mixed layer. The maximum dissipations 80 km from the island are not in the seasonal thermocline but rather at depths exceeding 250 m, where the values averaged over 5 m reach 10−4 W/m3 or more. The vertical thickness scales of the dissipative patches are of the order of 10 m. Statistical analysis shows that 80% of the estimates of ∈ are 10−5 W/m3 or less; the other 20% of the water column is responsible for 85% of the total energy dissipation.
Breaking invariants in shoaling waves
Authors: Van Dorn W. G.
Published: February 2008

The inability of present theory to describe correctly the shoaling transformation of surface gravity waves is well recognized. It owes, at least in part, to the lack of experimental information on internal flow fields. This paper describes a portion of the results from laboratory experiments in which the time histories of surface elevation, crest speed, and horizontal subsurface flow velocities in trains of uniform waves were measured at a plurality of stations before and after breaking, as functions of (uniform) beach slope and wave frequency. It was found that over gentle slopes, wave breaking is characterized by invariancy of crest profiles and kinematics and that most important breaking parameters can be expressed in terms of period and breaker height, the latter of which appears to be related simply to deepwater height and steepness.
Mean tropospheric residence time of cosmic‐ray‐produced beryllium 7 at north temperate latitudes
Authors: Bleichrodt J. F.
Published: February 2008

By means of published data on the concentration of 7Be in the troposphere between 30° and 75°N, together with concentrations measured over the Netherlands, the tropospheric content of 7Be has been estimated. Comparison of this value with published rates of deposition of 7Be in the same latitude band shows that the mean tropospheric residence time of this nuclide is probably not less than 22 days and is more likely of the order of 35 days. This is in agreement with previous estimates and not in agreement with the value of 1 week or less proposed recently by Martell and Moore.
Reactions of O2+ · O2 with CO2, O3, and CH4 and O2+ · O3 with H2O and CH4 and their role in stratospheric ion chemistry
Authors: Dotan I. , Davidson J. A. , Fehsenfeld F. C. , Albritton D. L.
Published: February 2008

The reactions of O2+ · O2 ions with the minor stratospheric neutrals CO2, O3, and CH4 have been studied in a variable temperature flowing afterglow to test whether they represent reaction paths that can compete with the one leading to H3O+ · nH2O ions and hence can offer the possibility of different terminal ions. The reaction of O2+ · O2 with CH4 was found to be too slow to be competitive. The measured equilibrium constants of the reactions with CO2 and O3 indicated that only the latter, which had an O2+ · O3 product, could play a stratospheric role. The O2+ · O3 ion chemistry was also examined. It was found that the reaction with CH4 was immeasurably slow but that the reaction with H2O was fast, yielding O2+ · H2O ions. Since this product ion is part of the sequence of reactions that lead to the H3O+ · nH2O ions, it is concluded that CO2, O3, and CH4 do not afford alternative reaction paths that could rationalize the recent in situ observation of non‐H3O+ · nH2O ions in the lower stratosphere.
Measurement of solar radiation at ground level in the region 1950–2150 Å using ammonia actinometry
Authors: Knoot P. , Reeves R. R.
Published: February 2008

The use of ammonia as an actinometer for measurement of the solar flux in the region 1950–2150 Å is presented. The solar flux was found to be 2.7 × 108 photons/cm2 s at ground level in this wavelength interval in an area with minimum overhead ozone concentration. The advantages of this method over previously used methods are discussed, and the results are related to the present estimates of the tropospheric photodissociation rates for the freons CFCl3 and CF2Cl2 by radiation in this wavelength region.
Asymmetric disturbances in the frontal zone of a Gulf Stream ring
Authors: Olson Donald B. , Spence Thomas W.
Published: February 2008

The present work represents a preliminary effort to investigate the dynamics of cyclonic Gulf Stream rings. As part of a multidisciplinary program, we have analyzed a closely spaced grid of expendable bathythermographs (XBT's) around the perimeter of a cyclonic ring. In conjunction with hydrographic data from the same cruise (Knorr 62), we examined the radial and azimuthal fields of temperature, vertical temperature gradient, and Brunt‐Väisälä frequency. After referencing the location of the observations to the estimated ring center, several vertical profiles were constructed to show radial and azimuthal variations. Azimuthal variations show influences of another smaller ring to the east, although other smaller scale perturbations are also evident. On the basis of simple conservation of potential vorticity, the influence of the ring to the east is shown to increase the stability in the region between the two cyclonic circulations. No subsequent observations are available from this ring, since it rejoined the stream shortly after this cruise.
Electrification experiments on Elk Mountain
Authors: Saunders C. P. R.
Published: February 2008

During the winter of 1976, along with the continuing studies of ice crystals in the cap cloud on Elk Mountain, measurements were made of ice crystal charges and the atmospheric electric field strength. The electric field was, in general, found to be of the same sign as the fair weather field. The net particle charges were predominantly positive with mean values of the order of ±10−14 C with fairly symmetrical distributions of positive and negative charges. The ‘mirror image’ effect was seldom observed perhaps because of the small extent and short lifetime of the cap cloud. The absence of large negative charges suggests that the particles and particle charges do not originate from blowing snow. A mechanism of charging which may explain the symmetrical charge distributions is inductive charge transfer between particles which contact and then separate in random directions relative to the electric field.
Sea surface temperatures in the North Pacific through the winter 1976–1977 from Nimbus 6
Authors: Kirwan A. D. , Guinasso N. L. , Mcnally G.
Published: February 2008

This is a preliminary analysis of sea surface temperature records from the North Pacific from July 1976 through June 1977. The observations were made by thermistors mounted on drifting buoys and were reported through a telemetry link in Nimbus 6. Typical time series of sea surface temperatures from the buoys show variability on scales ranging from a few hours to the seasonal march. Most conspicuous in the observations are a diurnal cycle associated with summer months, a 4‐ to 10‐day cycle associated with the passage of fronts during the fall and winter, and the seasonal marches of temperature. For the latter case a widespread event is responsible for most of the winter cooling. The warming cycle resembles more the classic sinusoidal march of temperatures. The large thermal anomaly present in the North Pacific during this period is clearly revealed.
Control of jet drop dynamics by organic material in seawater
Authors: Blanchard Duncan C. , Hoffman Eva J.
Published: February 2008

The ejection height of jet drops from bubbles bursting in seawater has been found to be a function of the time spent by the bubble rising to the surface. During this time, adsorption to the bubble of the surface active species of organic material in the water lowers the bubble surface free energy, the source of the kinetic energy of the jet drops. Experiments with a bubble aging tube have shown that the time rate of change of drop ejection height is a function of not only the amount of organic carbon in seawater but the species as well. Since changes in drop ejection height are paralleled by changes in drop size, the possibility exists that organics in the sea can play a role in modifying the drop size spectrum produced by the sea. On the other hand, the modification may be minimal, since the organic effect is most pronounced on the larger bubbles (about 1‐mm diameter) and less so on the smaller and more numerous bubbles produced by natural processes in the sea.
An observation of light emission from corona
Authors: Freier George D.
Published: February 2008

When electrical breakdown occurs in un‐ionized air, the generation of light is much greater when the discharge takes place from a positive electrode than it is from a negative electrode. The study is made by several methods of measurement.
A relation between the T‐S curve and global heat and atmospheric water transports
Authors: Stommel Henry M. , Csanady Gabriel T.
Published: February 2008

From historical data on the distribution of temperature and salinity on vertical sections across the oceans over complete latitude circles it is possible to test the compatibility of certain meteorologically determined meridional fluxes in the ocean of sensible heat and fresh water as functions of latitude. It is also possible to check the proportion of this flux that each ocean basin carries separately. The information from both these sources leads to estimates of the magnitudes and distribution of the meridional oceanic mass flux over the salinity‐temperature plane and yields some indication of the probable physical processes operating (that is isopycnal mixing versus large‐scale advective currents).
Identification of volcanic episodes in aerosol data at Mauna Loa Observatory
Authors: Bodhaine Barry A. , Harris Joyce M. , Herbert Gary A. , Komhyr Walter D.
Published: February 2008

Measurements of background atmospheric constituents at Mauna Loa Observatory, Hawaii, are occasionally subject to contamination by local effects such as upslope wind flow or volcanic emissions from Mauna Loa volcano. Volcanic episodes have been identified during 1978 with a sulfur dioxide meter operated at the observatory. In combination with surface wind data these SO2 measurements have been used to examine aerosol data, taken at the observatory, for volcanic episodes and to develop criteria to be used for screening other data taken at the observatory when SO2 measurements are not available. It is found that a requirement that Aitken nuclei concentration be less than about 840 cm−3 will eliminate only about 2% of the data during southerly wind conditions and still approximate the background conditions determined by independently removing known volcanic episodes.
Seasonal variations in high‐latitude ozone and metastable molecular oxygen emissions: A theoretical interpretation
Authors: Frederick John E.
Published: February 2008

Comparison of photochemical calculations of atmospheric ozone between 40 and 55 km with measurements from a satellite‐borne remote sensor shows acceptable agreement in the high‐latitude summer hemisphere. However, in the sunlit high‐latitude winter, the available data imply either a smaller water vapor mixing ratio than generally accepted or a temperature 15°–20°K colder than contained in published model atmospheres. High‐latitude measurements of the 1.27‐μ, column emission rate of O2(1Δg) carry information on lower‐mesospheric ozone and are well reproduced by theoretical calculations for summer conditions. As with the ozone data the infrared emission in winter implies an odd oxygen loss rate smaller than predicted on the basis of standard water vapor and temperature models. The magnitude of the 1.27‐μ signals and their consistency with upper stratospheric ozone data cast serious doubt on the large mesospheric ozone abundances deduced in independent experiments.
Remote sensing of the ozone profile in the lower stratosphere using UV and IR measurements from Nimbus 4
Authors: Prabhakara C. , Chandra S. , Modali Sarma B.
Published: February 2008

With a three‐parameter analytical model, the ozone profile below 10 mbar (∼30 km) to the surface is derived from the Nimbus 4 satellite backscattered ultraviolet and infrared measurements. Comparison of the derived profiles with those observed by ozonesondes shows that gross features are satisfactorily reproduced. Meridional cross section of the ozone partial pressure derived from the satellite data reveal the significant equator‐to‐pole features, as well as seasonal variability. An examination of the sensitivity of the method shows that an error in infrared radiance of ∼1 erg (erg Cm−1S−1Sr−1) leads to an error of about 10 mbar in the weighted mean pressure
of the ozone layer in the tropics, while at high latitudes the corresponding error in
is much larger.
Mesoscale circulation east of the southern Lesser Antilles
Authors: Mazeika P. A. , Burns D. A. , Kinder T. H.
Published: February 2008

We use vertical profiles obtained by salinity‐temperature‐depth and conductivity‐temperature‐depth profilers in winter 1977 and by airborne expendable bathythermograph in winter 1979 to examine the circulation east of the southern Lesser Antilles. The major flow feature, present both years, was an elongated cyclonic loop which apparently directed much of the flow toward Grenada Passage. Within the salinity maximum layer we found high salinities (>37‰) in Grenada Passage; such water was previously thought to enter the Caribbean only through more northern passages. An anomalous water mass, present at a few stations where the salinity maximum layer was relatively thicker, may have been an eddy similar to eddies observed elsewhere. Net westward transport between Tobago and Barbados was 15×106 m3/s (relative to 700 dbar), about one‐half the total flow into the Caribbean Sea.
Stratospheric free chlorine measured by balloon‐borne in situ resonance fluorescence
Authors: Anderson J. G. , Grassl H. J. , Shetter R. E. , Margitan J. J.
Published: February 2008

Eight balloon‐borne in situ measurements of ClO in the stratosphere are presented. Six of the observations, which were carried out close to local noon, are compared with recent model calculations at the appropriate latitude (32°N), altitude (25–45 km), and solar zenith angle interval (10° < χ < 55°). The ClO mixing ratio by volume observed on four flights between the autumnal equinox and the winter solstice (September 20, October 25, December 2, and December 8, 1977)is found to exhibit little variability, defining an envelope which decreases from 0.5 to 1.1 ppb at 42 km to 10 to 50 ppt at 25 km. Two observations in July (July 28, 1976, and July 14, 1977) indicate significantly higher mixing ratios, the former increasing from 0.8 ppb at 42 km to 1.8 ppb at 36 km and then decreasing to 0.1 ppb at 24 km in reasonable agreement with calculations using 2.2 ppb total chlorine and 8 ppm H2O at the stratopause. The latter summer observation exhibits a serious divergence from calculated densities above 32 km, reaching 7 ppb in a layer between 35 and 40 km. Emphasis is given to a description of laboratory simulation experiments done in parallel with the stratospheric observations and to techniques used for determining the absolute sensitivity of the instrument. Results of the in situ observations are compared with recent results from the laser heterodyne and microwave limb scanning remote sensing methods. The simultaneous observations of [ClO] and [O3] on July 14, 1977, are used in conjunction with a formulation of odd oxygen chemistry in terms of rate limiting steps to deduce that either (a) the [ClO] or [O3] observation is wrong, (b) the observed chlorine was injected into the stratosphere in a period short in comparison with the chemical response time of ozone, or (c) there are important mechanistic steps missing from stratospheric chlorine‐ozone photochemistry.
Spatial correlations in wind‐generated water waves
Authors: Komen G. J.
Published: February 2008

Recently, laboratory measurements of wind‐generated deepwater waves have been made by Ramamonjiarisoa and Coantic and by Lake and Yuen. They found that the phase velocity was independent of frequency at least for a certain range of frequencies. One explanation for this unexpected result has been given by Longuet‐Higgins, who made a specific assumption about the directional wave number spectrum. Another tentative explanation ascribes the observed constancy to nonlinear effects. In this note, model spectra based on these explanations are studied, and it is shown how a relatively simple measurement of the cross‐spectral density at 90° to the wind direction could discriminate between these different models.
Direct measurements in the Labrador Current
Authors: Mountain D. G.
Published: February 2008

Direct measurements of the Labrador Current along the eastern edge of the Grand Banks were made for a 77‐day period (April–June) in 1977. The mean current was southward parallel to the isobaths with speeds of 46 cm s−1 and 18 cm s−1 at 110 m and 380 m depth, respectively. In addition to a semidiurnal tidal signal the current variations appear to be of two primary types. A low‐frequency (10‐ to 16‐day period) variation dominates the current records at both depths and is coherent with the local wind stress. A 2‐ to 4‐day period variation is evident in the measurements at 110 m depth.
The calibration of a hot film turbulence probe
Authors: Lueck Rolf G.
Published: February 2008

The calibration data of two cone‐shaped platinum thin film turbulence probes used for oceanic measurements show that the rate of heat transfer from the film to the fluid is not proportional to U0½ as expected for a constant temperature conical surface. A thermal model of the probes that agrees favorably with the calibration data indicates that this nonproportionality is due to the thermal effect of the glass coating over the film and glass substrate below it. The unsteady heat flux from the film in response to variations in the ambient fluid's speed increases with increasing frequency above 100 Hz. It is shown that the unsteady heat flux is proportional to the unsteady viscous surface stress over the film, which increases in magnitude with increasing value of the frequency parameter ωL/3U0. The ratio of the temperature‐to‐velocity sensitivity is highest at zero frequency.
Radar observations of wave transformations in the vicinity of islands
Authors: Vesecky J. F. , Hsiao S. V. , Teague C. C. , Shemdin O. H. , Pawka S. S.
Published: February 2008

During the West Coast Experiment both in situ measurements (by wave buoys and by pressure arrays) and remote observations (by ground based high‐frequency (HF) radar and by airborne synthetic aperture radar (SAR)) were made to study the effects of offshore islands on the near‐shore wave climate. The radar results reported here concern March 25, 1977, a day of moderate winds blowing out of the west at ∼7 m s−1. The Torrey Pines near‐shore pressure array indicated that the dominant wave period was 7 s arriving with a bimodal directional distribution centered approximately on west and northwest. The overall picture, which emerges from these observations of 7 s period waves, shows a broad, deep‐ocean directional distribution arriving out of the west, being significantly modified as it propagates coastward passing San Clemente and Santa Catalina islands. The salient features introduced by the islands are a window between the islands, where an enhanced wave energy level is observed traveling eastward toward the southern California coast and a large shadow region extending some 50 km east of San Clemente Island in which eastward propagating wave energy is reduced by a factor of about 3. Although reduced in energy level, there are in fact eastward propagating waves in the shadow region where one would expect no eastward traveling waves at all based on geometric arguments. We have made estimates of the eastward moving wave energy introduced into the shadow region by reflection, refraction, diffraction, and wind generation processes, and we find that none of these mechanisms can account for the observed wave energy. SAR observations reveal a significant directional component traveling approximately transverse to the shadow region (parallel to the long dimension of the island). It is possible that nonlinear wave transfer driven by this directional component is the mechanism which produced the aforementioned eastward traveling waves in the shadow region. Further computation, beyond the scope of this paper, is required to evaluate this possibility. Intercomparisons between HF and SAR measurements as well as between radar and in situ observations confirm the current methods used to interpret the radar data. Although this confirmation is reassuring and this study demonstrates the efficacy of SAR and HF wave sensing techniques, research is needed to exploit SAR and HF radars fully as remote sensing tools in physical oceanography.
Characteristics of lightning from frontal system thunderstorms
Authors: Kitterman C. Gill
Published: February 2008

A slowly rotating streak‐camera array was used to photograph lightning flashes to ground from thunderstorms associated with 13 large frontal systems. Photographs of 139 flashes were obtained at Kansas City, Missouri, during 1979. Comparison of the frequency distributions of flash duration between frontal thunderstorms and air mass thunderstorms over nonmountainous terrain showed little difference between the two. However, comparison of the distributions of the number of strokes per flash indicated that frontal thunderstorms produce a greater percentage of high‐order multiple stroke ground flashes than do air mass thunderstorms.
Molecular hydrogen in the urban troposphere: Measurement of seasonal variability
Authors: Scranton Mary I. , Barger William R. , Herr Frank L.
Published: February 2008

Molecular hydrogen was measured during January–February and June–July 1979 at a monitoring station at the Naval Research Laboratory (NRL), Washington, D.C. Automatic sampling allowed analysis of a sample‐standard pair each 9 min throughout the study period. Results show H2 concentrations ranging from near ‘clean air’ values (0.6 ppmv) to concentrations exceeding 3 ppmv. Maxima appeared and dissipated over periods of a few (3–5) hours, and H2 appeared to correlate well with CO and NOx but poorly with SO2. The bimodal H2 distribution observed in winter follows the traffic patterns near NRL well, but during the summer only the midmorning peak correlated well with traffic; the second H2 concentration peak occurs after the maximum traffic load. On the other hand, the timing of both winter and summer peaks appears to be related to patterns of atmospheric boundary layer formation and decay. The data suggest that H2 in the urban troposphere is largely controlled by periodic motor vehicle input (twice daily) and diurnal loss owing to a meteorological flushing (boundary layer collapse and wind action).
The ocean tide in the southern Ross Sea
Authors: Williams Richard T. , Robinson Edwin S.
Published: February 2008

A survey of the ocean tide in the southern Ross Sea was done by measuring tidal variations of gravity at nine locations on the floating Ross Ice Shelf. Tidal water level fluctuations were calculated from recordings between 29 days and 58 days long of the periodic variation in gravity on the ice shelf surface that is caused by tidal changes in elevation and water mass. Conventional tide gauge measurements from McMurdo Sound were included in the survey. The data indicate that the Ross Sea tide is principally diurnal. Along the northern margin of the Ross Ice Shelf the tropic (diurnal spring) tidal range is between 1 m and
; m. The range increases to more than 2 m in the southernmost part of the Ross Sea. It is more than 3 times larger than the equatorial (diurnal neap) tidal range. Amplitudes of the principal diurnal constituents K1 P1 and O1 are apparently magnified by a condition of diurnal resonance in the Ross Sea. This would be expected because wavelengths of the diurnal harmonic constituents are approximately 4 times the length of the Ross Sea in the direction of propagation. The diurnal constituent amplitudes also appear to vary proportionally with the fourth root of the water depth as predicted from the theory of long wave propagation in a canal. Semidiurnal constituents M2, S2, and N2 have small amplitudes and appear to progress clockwise around amphidromes located beneath the northwestern part of the Ross Ice Shelf.
Tropospheric gas‐phase and particulate nitrate measurements
Authors: Huebert B. J. , Lazrus A. L.
Published: February 2008

Measurements of HNO3 vapor and particulate NO3− were made in 1977 and in 1978 over western North America and the Pacific Ocean, both in the boundary layer and in the free troposphere. The boundary layer HNO3 ranged from <0.01 to 0.86 ppbv, with a median of 0.06–0.08 in remote areas. Free tropospheric HNO3 was more uniform, ranging from <0.03 to 0.54 ppbv with a median of 0.12 ppbv. The lack of an average gradient from 70°N to 55°S at 5–6 km suggests that a dispersed natural NOx source is responsible for this free tropospheric HNO3, rather than an anthropogenic one, since most urban NOx is emitted in the northern hemisphere. This and the large variability of boundary layer HNO3 with proximity to populated areas suggest that much anthropogenic NOx is removed fairly near its source. Particulate nitrate varied from <0.04 to 0.8 ppbm (median 0.11) in the free troposphere and from <0.04 to 3.5 ppbm (median 0.15) in the boundary layer. The molar ratio of vapor to particulate nitrate is generally much larger than 1 in the free troposphere.
Formation and evolution of ultrafine particles produced by radiolysis and photolysis
Authors: Madelaine G. J. , Perrin M. L. , Renoux A.
Published: February 2008

Results are presented, concerning the formation, the size distribution, and the behavior of ultrafine particles produced by α disintegration of actinon and UV irradiation in filtered and natural atmospheric air. The characterization of these particles is obtained by electrical aerosol analyzer and diffusion battery method. Measurements are made in the range between 0.003 and 0.5 μm. Some qualitative indications are obtained on the different mechanisms which govern the evolution of ultrafine particles in the atmosphere (nucleation, coagulation, and condensation).
Measurements of nitric oxide after a nuclear burst
Authors: McGhan M. , Shaw Alan , Megill L. R. , Sedlacek W. , Guthals P. R. , Fowler M. M.
Published: February 2008

Measurements of ozone and nitric oxide in a nuclear cloud 7 days after the explosion are reported. No measurable increase above ambient density of either ozone or nitric oxide was found. Results from a chemistry model of the cloud do not agree with the measurement unless ‘nonstandard’ assumptions are made with regard to the operating chemical processes. A number of possible explanations of the results are discussed.
Improved airborne measurements of OH in the atmosphere using the technique of laser‐induced fluorescence
Authors: Wang Charles C. , Davis L. I. , Selzer P. M. , Munoz Robert
Published: February 2008

Improvements in the fluorescence technique for OH measurements in the atmosphere are described, and results of airborne measurements are presented. Previous fluorescence measurements are also discussed in the light of current understanding.
On the depth interpolation of repeated hydrographic data
Authors: Frankignoul Claude
Published: February 2008

A new method is presented for the depth interpolation of hydrographic data below the level of direct seasonal influence. It consists of interpolating (here, linearly) the departures of individual station data from a mean profile that has been estimated by cubic spline smoothing from an ensemble of stations occupied at the same or nearby locations. Repeated temperature profiles taken at the Panulirus station off Bermuda are used for illustration. The rms interpolation error is estimated for a very large number of temperature measurements between 220 and 2000 m and compared to rms interpolation errors obtained with other methods. The new scheme performs best, particularly in data sparse regions. The interpolation method currently used at the National Oceanographic Data Center and the Aitken‐Lagrange interpolation yield a 30% larger rms interpolation error; the interpolation error for linear interpolation is more than 80% larger. The applicability of the interpolation method using the mean profile is also tested in the case where only a few stations are available to define the mean. Although the error reduction is smaller, the method still performs best when sets of four or more stations are available.
A wintertime temperature inversion in Kootenay Lake, British Columbia
Authors: Wiegand Ronald C. , Carmack Eddy C.
Published: February 2008

We describe the wintertime development and persistence of an anomalous temperature inversion layer in a deep temperate lake with emphasis on the roles of convective mixing and river‐induced circulation. The layer is about 20 m thick, 100 km long, and lies at a depth of 60–80 m. The destabilizing temperature distribution is compensated by a very weak (0.015 ppt) salinity increase across the inversion layer. We observe that neither the energy available from the wind nor the buoyancy extracted at the surface via a negative heat flux are sufficient to penetrate the depth of the inversion. Calculations of a thermal diffusion coefficient for this layer indicate a weak turbulent exchange below the halocline. Lake overturn does not follow the classical pattern of surface processes driving complete winter mixing; rather, full circulation is made possible only by the input of relatively saline river water.
Wind wave directions determined from synthetic aperture radar imagery and from a tower in Lake Michigan
Authors: Schwab David J. , Shuchman Robert A. , Liu Paul C.
Published: February 2008

Directional wave spectra calculated from digitized synthetic aperture radar (SAR) images of waves on Lake Michigan are compared to a wave directional spectrum determined from measurements taken at a tower and to a one‐dimensional spectrum determined from a Waverider buoy. The comparison is within one frequency band for peak energy frequency and within 20° for direction, but the SAR image intensity spectrum does not have the same shape as a wave height spectrum. Wave refraction directions observed in the SAR spectra are within 10° of classical wave refraction calculations.
Stratospheric odd‐nitrogen: NO measurements at 51°N in summer
Authors: Ridley B. A. , Hastie D. R.
Published: February 2008

The altitude distribution of nitric oxide was measured during three balloon flights in August 1976 and 1978. Median values of the volume mixing ratio at 18, 24, 30, and 34 km were 0.4, 1.4, 6.5, and 13 ppb, respectively. The data are discussed in relation to an average profile of nitrogen dioxide measured for this season and latitude and in relation to current one‐dimensional models of the stratosphere.
Nitric oxide from nitrite photolysis in the central equatorial Pacific
Authors: Zafiriou O. C. , McFarland M.
Published: February 2008

Sunlight photolyzes nitrite in seawater: NO2− + HOH + hv = NO + OH + OH−. We studied nitrite loss and nitric oxide production attributed to this reaction in surface waters of the equatorial Pacific near 170°W. Net photochemical loss rates of 2–15% per day were derived from two different types of laboratory incubation experiments. The net nitrite loss rate in the surface water of this region is calculated to average 4 × 10−13 mol l−l s−l during the day, or ∼6 × 10−2 mol m−2 y−1. Nitric oxide was detected in situ with a floating gas‐seawater equilibrator. NO was always detectable in nitrite‐containing seawater during the day but was undetectable at night or in nitrite‐free water. Near sunrises and sunsets the estimated NO vapor pressure, pNO(sea) covaried with the ambient UV insolation in air according to log pNO(sea) = a log UVair + b. Best‐fit values to the in situ data indicate a ≈ 1 with r2 ≥ 0.9; simple kinetic models rationalize a values of O, ½, or 1. During the day, pNO(sea) averaged ∼3.1 × 10−8 atm, corresponding to ∼4.6 × 10−11 M [NO]aq. The ambient atmospheric pNO was ∼104 ‐fold lower, implying a substantial seawater supersaturation and a sea → air flux. From the stagnant‐boundary layer model and our measurements, we estimate ∼2 × 10−16 mol 1−1 s−1 (∼1.3 × 108 molecule cm−2 s−1) of NO efflux in daylight, an insignificant NO loss from the sea. The photochemical NO source and the estimated dark reaction sink are, within the accuracy of the data, in balance. These results provide evidence for the presence of NO, a free radical, in surface seawater. They substantiate that photochemical reactions produce measurable concentrations of reactive intermediates in surface seawater and that these enter into rapid secondary reactions. These processes may reach sufficient intensity to provide significant effects, such as sea → air fluxes.
214Bi/214Pb activity ratios in the atmosphere
Authors: Rangarajan C. , Eapen C. D.
Published: February 2008

The ratios of 214Bi to 214Pb in the surface atmosphere at Bombay on the west coast of India have been measured. In all, about 500 measurements were carried out at the ground surface and on top of a building 20 m high. The analysis techniques consisted in the least squares resolution of the alpha decay curves of high volume air filter samples counted by using large ZnS scintillation detectors. The collection and counting periods were optimized for minimizing the errors. The sample collection procedure consisted in taking a morning and an afternoon sample everyday. The measured ratios varied from 0.3 to 1.0, the average values being in the range 0.6–0.9. The afternoon ratios were generally higher than were the morning values. The data also showed that during late winter and spring the ratios reached the minimum values observed during the year. The possible reasons for the variations in the measured ratios are discussed.
Further measurements of carbon dioxide concentration and flux in a large agricultural region of the Great Plains of North America
Authors: Verma Shashi B. , Rosenberg Norman J.
Published: February 2008

Observations of CO2 concentration and flux made from June through September 1978 are reported for an area of typical agricultural land use in the east central Great Plains of North America (Mead, Nebraska). Data are compared with earlier observations made at the same site. An increase in carbon dioxide concentration of about 0.9–1.2 ppm per year has occurred in the intervening 5 years. This increase is in agreement with other globally distributed CO2 concentration measurements in oceanic and polar regions. Flux calculations were based on measurements made at elevations sufficiently high above the ground so that they represent an integration of the carbon dioxide exchange of the region generally rather than of a single field or crop. CO2 flux rates were greatest around middle to late July. The annual minimum in carbon dioxide concentration occurs during the same period. These observations suggest a distinct peak in photosynthetic activity in the region at this time. Not all crops behave in the same way, however. Large area CO2 flux estimates based on an extrapolation of data from individual crops or fields should be avoided.
Scattering from volume variability
Authors: Goodman Louis , Kemp Kenneth A.
Published: February 2008

Acoustic scattering cross sections for medium fluctuations are derived from the funadmental wave equation. Analysis of the effect of a finite scattering volume is made. Fluid velocity fluctuations are shown to produce no backscatter at scattering angle θ = 180° independent of the statistical form of the velocity field and valid for both atomspheric and oceanic cases. Scattering cross sections for the atmospheric and oceanic cases are compared. Temperature fluctuations for the atmospheric case result in a scattering cross section proportional to a cos2 θ factor whereas for the oceanic case no such factor arises. Using a cylindrically symmetric form about the vertical direction for temperature fluctuations, explicit expressions for the angular dependence of the scattering cross sections are obtained. These results depend strongly on the parameter α, the ratio of the vertical length scale of the temperature variability to the horizontal length scale. For a typical echo sounder operating at 20 kHz, scattering strengths based on observed one dimensional spectra of temperature microstructure are of order −120 dB if isotropy is assumed (α = 1). For the layered case, where the horizontal scale of the variability is larger than the horizontal dimension of the scattering volume, the same values of variability yield, scattering strengths are of order −70 dB. These results can be applied at other frequencies provided the medium variability spectrum is known.
Current structure on the Long Island inner shelf
Authors: Han Gregory C. , Mayer Dennis A.
Published: February 2008

Current velocity records from a deployment of 17 current meters across a ridge and swale topography with a 5 m amplitude, 6.5 km off the coast of Long Island, were analyzed to determine the interaction between the flow field and the topography which might maintain these special bottom features. No first‐order interactions were found; the flow field was generally parallel everywhere. Correlation, coherence, and empirical orthogonal modal (EOM) analysis showed no significant differences between meters as a function of alongshore or cross‐shore separation. EOM analysis showed that 79% of the variance was in the first barotropic mode with a strong vertical shear that was probably related to friction. Tide and wind response models can replicate about 64% of the variance in the alongshore velocity, of which about 30–40% is tidal. The residual record, uncorrelated to wind or tide, shows the effect of alongshore variations in the pressure field following a storm event by reversing the flow opposite to the diminishing wind stress. By regression of the averaged alongshore bottom velocities to wind stress, a linear bottom friction coefficient of 0.14 cm s−1 is found, which is in agreement with previous estimates, and a time average alongshore pressure gradient of 0.3 × 10−7 is found which is an order of magnitude smaller than previous estimates. By scaling the results of the wind response model, the linear bottom friction coefficient is also found to be 0.14 cm s−1.
Fronts, stratification, and mixing in Long Island and Block Island sounds
Authors: Bowman Malcolm J. , Esaias Wayne E.
Published: February 2008

Spatial patterns of bulk stratification in Long Island and western Block Island sounds observed near the fall equinox of 1978 show a strong correlation (r = 0.79) with contours of the h/U3 stratification index derived from tidal stream and depth charts. The index delineates stratified, transitional, and mixed regions with apparent good accuracy, with the marginally stratified frontal zones being characterized by log10 h/U3 ∼ 1.5 m−2 s3. These results and theoretical considerations suggest that the index may be a useful parameter in corroborating and predicting frontal boundaries in other moderately stratified estuaries where local buoyancy fluxes are derived from fresh water sources.
Spectroscopic measurements of the vertical column, abundance of hydroxyl (OH) in the earth's atmosphere
Authors: Burnett Clyde R. , Burnett Elizabeth B.
Published: February 2008

Extensive new information on the daytime column abundance of atmospheric OH is presented from Spectroscopic observations of sunlight absorption by the P1(I)A2Σ+ – X2π(0, 0) transition of OH at 3081.7 Å, taken with a Pepsios spectrometer. The observations were made from the NOAA Aeronomy Observatory at Fritz Peak, Colorado, between December 1976 and December 1979. An overall seasonal dependence on the depth of penetration of the solar ultraviolet flux, which is believed to initiate the photochemistry of daytime OH, was found. The overall averaged data is represented by an empirical curve, N(sec χ), where χ is the solar zenith angle, showing an overhead sun maximum abundance of 7.1 × 10l3/cm2, decreasing to 4.9 × 1013/cm2 at sec χ = 2.0. The OH abundance and the sec χ variation agree reasonably well with predictions given by recent theoretical models of the stratosphere and mesophere and with the analysis of earlier in situ measurements of stratospheric and mesospheric OH by Anderson. An OH abundance increase of about 1 × 1013/cm2 per year is found for the 1976–1979 period. There was a seasonal variation in 1978 with a 25–30% decrease from a springtime maximum to a fall minimum. The 1978 abundances also show a 30–40% diurnal oscillation whose cause is as yet undetermined. This effect is shown to be dependent on solar flux on both a diurnal and an annual basis, and the 1978–1979 observations exhibit additional long‐term changes, possibly related to the solar cycle, which will be monitored in future work.
Return stroke velocity measurements in two triggered lightning flashes
Authors: Hubert P. , Mouget G.
Published: February 2008

Triggered lightning experiments at St. Privat d'Allier (France) enabled the three‐dimensional return stroke velocity VRS and the electric current intensity, I, to be measured simultaneously for two multistroke triggered flashes. For the first strokes, VRS = 6.1 ± 1.5 107 m/s with Imax = 19.5 ± 1 kA and VRS = 6.1 ± 1 107 m/s with Imax = 8.2 ± 2.5 kA in reasonable agreement with current theory. For nine subsequent strokes with rise time shorter than 1.5 μs, Imax lies between 3.1 ± 0.9 and 16.6 ± 5 kA and VRS between 6.1 ± 1 and 17.4 ± 3 107 m/s. The latter values are 2 or 3 times higher than was predicted.
An approach to determining pathways and residence time of groundwaters: Dual radiotracer dating
Authors: Gupta S. K. , Lal D. , Sharma P.
Published: February 2008

In a highly dispersive groundwater flow system (D/ux ≫ 1), application of piston flow model leads to considerable overestimation of flow velocity. In the case of semiconfined aquifers, the flow velocity is further overestimated due to addition of relatively young water through leakage from overlying shallow aquifers. In this paper we discuss how, based on simultaneous measurements of two radiotracers of widely differing half lives, one can obtain meaningful estimates of the aquifer parameters, namely, the flow velocity, dispersion coefficient, and the leakance. We have studied the behavior of a radiotracer by using the diffusion‐advection equation for the steady state groundwater movement through porous media and analyzed the propagation of the radiotracer along the direction of flow in the aquifer for different aquifer parameters and tracer half‐lives. Uncertainties arising due to nonradioactive loss of radiotracers are discussed in detail. The errors in the estimation of the mean dispersion time (D/u2) arising from (1) finite errors in the measurement of radiotracer concentrations and (2) finite nonradioactive loss of the tracers in the aquifer have been evaluated. These calculations allow one to select a suitable ‘pair’ of radiotracers for a given field situation.
CACGP symposium
Authors: Cicerone Ralph J.
Published: February 2008

This is the last of four issues to have a section devoted to papers presented at the Symposium on Budget and Cycles of Trace Gases and Aerosols in the Atmosphere. (Journal of Geophysical Research, 85, August 20, 1980, contained the first group of papers; October 20, 1980, contained the second; and December 20, 1980, contained the third.) Held August 12‐18, 1979, in Boulder, Colorado, the symposium was part of the Fourth International Conference of the Commission on Atmospheric Chemistry and Global Pollution (CACGP). The principal convenor of the symposium was the past CACGP Secretary, P. Goldsmith, of the Meteorological Office, Bracknell, United Kingdom; his efforts were complemented by the past CACGP President, E. A. Martell, of the National Center for Atmospheric Research, Boulder, Colorado.
Correction [of “Atmospheric N2O mixing‐ratio data”]
Authors: Goldan P. D. , Kuster W. C. , Schmeltekopf A. L. , Fehsenfeld F. C. , Albritton D. L.
Published: February 2008

All of our previously published atmospheric N2O mixing ratio data must be divided by 1.07 to correct for an error that we have recently discovered in our 1975 N2O primary standard. This problem was uncovered during intercomparison of our electron‐capture, gas‐chromatographic measurement technique for N2O with a newly developed infrared absorption technique (Connell et al, 1980). The salient features of this intercomparison, the subsequent recalibration of our standards for N2O, CFCl3, and CF2Cl2, and the consequences of the correction required for our N2O data are summarized here.
Distribution of microbubbles in coastal waters
Authors: Mulhearn P. J.
Published: February 2008

Likely mechanisms for bubble generation and persistence in the ocean are discussed. It is suggested that the larger bubbles (radius >60 μm) may be generated continuously by decaying matter on the sea floor, but that smaller ones (radius <60 μm) persist indefinitely, once formed, because of surfactant coating and attachment to particles. Simple mathematical models for these hypotheses are constructed and found to compare favorably with the data of Medwin (1970).