bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance characteristics of the electrochemical concentration cell ozonesonde
Authors: Torres A. L. , Bandy A. R.
Published: February 2008

A large number of electrochemical concentration cell ozonesondes were calibrated in relation to an ultraviolet photometric absorption ozone instrument prior to using the ozonesondes in atmospheric soundings. The two methods of measuring ozone were in reasonable agreement on the average, but there was considerable variation from one ozonesonde to another. Averaging the individual linear regressions gives [O3]ECC = 0 ± 8 nbar + (0.96 ± 0.10)[O3]UV, where uncertainties represent 90% confidence limits. Applying individual calibration corrections to atmospheric sounding data reduced the mean difference between Dobson spectrophotometric measurements of total ozone overburdens and corresponding values obtained from ozonesonde data from −8.5 ± 8.2 to −1.4 ± 7.3% for a series of measurements carried out in 1977. Corresponding uncorrected and corrected differences averaged 3.2 ± 9.7 and 1.9 ± 10.6%, respectively, for soundings carried out in 1976.
Longshore currents on the fringe of Hurricane Anita
Authors: Smith Ned P.
Published: February 2008

Subsurface current data from a 2‐week period in August and September 1977 are compared with coastal wind stress and water level data to describe longshore motion in reponse to the passage of Hurricane Anita across the northern Gulf of Mexico. Current meters 2 and 10 m above the bottom 21.5 km off the central Texas Gulf coast indicate strongest speeds of approximately 70 and 80 cm/s, respectively, coinciding closely with the time of maximum wind stress. A qualitative comparison of the variations in sea surface slope and wind stress with the recorded longshore current suggests that both wind stress and the longshore pressure gradient combined to produce the strong flow recorded during the storm but that the pressure gradient was primarily responsible for decelerating the current after the storm made landfall.
Stratospheric‐tropospheric exchange at polar latitudes in summer
Authors: Danielsen E. F. , Hipskind R. Stephen
Published: February 2008

Measurements of ozone number mixing ratio made in the mean troposphere, both within and above the boundary layer, at 60°N latitude over Canada in the summer of 1977, range from <20 to >200 ppb. Isentropic analyses of the dynamic tropopause, on the basis of a potential vorticity threshold, show that the large‐scale anomalies are related to traverses of a multiply folded tropopause; therefore, the large values of ozone are of stratospheric origin. Values <30 ppb are shown to be made directly in the boundary layer or in moist air which can be traced back to a boundary layer. The distinctions between the conventional and dynamic tropopause are discussed, and the use of potential vorticity as a stratospheric tracer is defended.
Predicting fluxes of latent and sensible heat of lakes from surface water temperatures
Authors: Bill R. G. , Cook A. F. , Allen L. H. , Bartholic J. F. , Maki T.
Published: February 2008

Wind velocity, air temperature, and humidity fluctuations were measured over Orange Lake, Florida, using an ultrasonic anemometer‐thermometer and Lyman alpha humidity sensor. Latent and sensible heat fluxes were calculated from the data using the eddy correlation technique. Lake temperature at a 2.5‐cm depth was measured in order to compare eddy correlation results with fluxes and the Bowen ratio predicted by the formulae of Hicks (1975) and Priestley and Taylor (1972) in which temperature is the sole parameter. Bowen ratio results were in good agreement with the formulations of Hicks (1975) and Priestley and Taylor (1972) if property values were evaluated at a temperature intermediate to the lake and 10‐m air temperature. Disagreement with fluxes predicted by Hicks (1975) indicates that such formulations are inadequate for short‐term flux evaluations under the meteorological conditions in which surface water temperature is changing with time.
A comparison of vertical and isopycnal mixing models in the deep sea based on radon 222 measurements
Authors: Sarmiento J. L. , Rooth C. G. H.
Published: February 2008

A two‐dimensional model is developed for the one‐dimensional depth‐dependent distribution of a radioactive tracer with a bottom source (e.g., radon 222) in a weakly baroclinic fluid. The tracer transport away from the boundary is separated into two components with cardinal directions along and perpendicular to isopycnal surfaces in the fluid. Contrary to the case of a strictly one‐dimensional mixing model, where properties such as heat and buoyancy have the same vertical eddy diffusivity as the tracer so that their vertical fluxes are uniquely related, this model yields a relation between vertical buoyancy and heat fluxes and the tracer flux which depends on the relative magnitude of the isopycnal and crossisopycnal diffusivities. To close the problem, we assume that the interior vertical buoyancy flux is balanced by a horizontal cross‐isopycnal Ekman drift at the bottom. As an example, a bottom radon 222 profile (Geosecs station 31) is analyzed. The buoyancy flux implied by the apparent vertical radon 222 diffusivity of 46 cm2 s−1 is 2.1×10−6 cm2 s−3, requiring a bottom friction velocity (u*) of 0.94 cm s−1 to balance it in a one‐dimensional model. In the two‐dimensional isopycnal mixing model the buoyancy flux can take on any value between 0 and 2.1× 0−6 cm2 s−3 with corresponding values for u*, which was not measured, of 0–0.94 cm s−1. For an assumed u* value of 0.1 cm s−1 the cross‐isopycnal diffusivity is 0.5 cm2 s−1, implying a vertical buoyancy flux of 2.3×10−8 cm2 s−3, and the diffusivity parallel to the isopycnals is 3.8×106 cm2 s−1.
Spatial scales of temperature and flow in Drake Passage
Authors: Sciremammano F. , Pillsbury R. D. , Nowlin W. D. , Whitworth T.
Published: February 2008

An analysis of 3 years of current meter data (1975, 1976, and 1977) from Drake Passage is used to assess the vertical and the horizontal scales of temperature and flow. It is found that temperature and current fluctuations are highly correlated vertically in the mid‐depth range. The only exceptions are in the temperature structure in the upper layers (300–500 m) which is complex and not well correlated with that in the deeper layers and a relative increase in current variability at depths near 3000 m, and below. Most of the measurements were near the southern edge of the Polar Frontal Zone where it is found that the horizontal scales for temperature fluctuations are approximately equal in the through‐ and the across‐passage directions at 100–110 km. If the data from the entire passage is used, this scale is reduced to approximately 80 km. The velocity fluctuations in the through‐ and the across‐passage directions are found to be narrow (of the order of 30–40 km) normal to their flow direction and elongated (55–80 km) parallel to it. These measured spatial scales are shown to be consistent with observations of individual mesoscale disturbances reported from this region of the Antarctic Circumpolar Current. The observed disturbances are generally in the form of meanders or lateral excursions of the narrow current core associated with the polar front or of rings formed from separations of loops of this current. The polar front, and the associated current core, are found to migrate north and south on a time scale of months. A northward shift of the front during the austral winter is indicated in the records from all 3 years. Although the correlations at large separations (>100 km) were generally small, an analysis of their sign structure indicates a small response is present at scales on the order of half the passage width. This response fits into the general zonation pattern found from expendable bathythermograph traces (XBT) and hydrographic surveys.
The role of H2SO4 in stratospheric negative‐ion chemistry
Authors: Viggiano A. A. , Perry R. A. , Albritton D. L. , Ferguson E. E. , Fehsenfeld F. C.
Published: February 2008

Gas‐phase ion‐molecule reactions involving H2SO4 and a variety of positive and negative atmosphericions have been studied by using a flowing afterglow apparatus. These ions include NO3− · nHNO3 (n = 0, 1, 2) and H3O4+ · nH2O (n = 0, 1, 2, 3). All of the negative ions studied react rapidly with H2SO4 to form HSO4− · nHNO3. These reactions establish a lower limit for the electron afiinity of HSO4:4.5 eV. They also indicate that the terminal negative ions in the upper stratosphere will be cluster ions of the type HSO4− · nH2SO4 · mHNO3, which is in accord with recent in situ observations. On the basis of the present laboratory results and the reported in situ ion composition measurements, the H2SO4 concentration at 35 km is estimated to be 6×105±1.6 cm−3. It is found that H2SO4 probably plays very little role in stratospheric positiveion chemistry, since it does not replace H2O in the H3O+ · nH2O ion clusters.
Diurnal fluctuations of Br and I in the tropical marine atmosphere
Authors: Rancher Jacques , Kritz Mark A.
Published: February 2008

Concentrations of Na, Cl, Br and, I in aerosols and in inorganic gases were measured in the marine atmosphere off the west African coast (∼0°N; ∼0°W) in June 1977. During 8 days of the voyage, the meteorological situation was stable and well defined, and there was no precipitation, allowing a steady state analysis to be made of the mean rates of production and removal of the principal constituents of the system. Superimposed on these mean fluxes, strong diurnal fluctuations in the concentrations of Br and I (but not Na or Cl) were observed. Daytime concentrations of gaseous inorganic Br and I were about double their nighttime values. During this same period, the daytime concentrations of particulate Br were about half their nighttime values, while particulate I concentrations showed only small, uncorrelated variations. Analysis of these results suggests that there may be a reversible, day‐night exchange of Br between the particulate and gas phases; for I it is speculated that at night an appreciable fraction of the gaseous inorganic I present existed in a form not efficiently trapped by the LiOH‐impregnated filters of our sampling apparatus.
Experimental evidence of natural sources of CO from measurements in the troposphere
Authors: Marenco Alain , Delaunay Jean Claude
Published: February 2008

A very sensitive method of CO detection in the air, based on gas chromatography, has been developed in view of a study of the natural sources and atmospheric behavior of carbon monoxide. The CO variations found in forest air in France (44°N) and in the Ivory Coast (5°N) confirm the existence of a natural CO formation by vegetation. The similarity of the results suggests a homogeneous abundance in the planetary boundary layer over the continents. The tropospheric measurements are in good accordance with the data published in the literature except for the free atmosphere of the north hemisphere mid‐latitudes where CO mixing ratios (70–110 ppb in oceanic air), inferior to those of Seiler (1974) (200–250 ppb), are obtained. From the CO budget based on various recent results it appears that the CO tropospheric residence time is short, of the order of 0.1 to 0.2 year. Consequently, the latitudinal CO distribution may be explained by the latitudinal repartition of natural sources rather than by the anthropogenic one (CO air concentrations, natural formation, residence time.)
Atmospheric SO2 measurements on Project Gametag
Authors: Maroulis P. J. , Torres A. L. , Goldberg A. B. , Bandy A. R.
Published: February 2008

On the 1978 Global Atmospheric Measurements Experiment of Tropospheric Aerosols and Gases (Gametag) flights, 201 measurements of the tropospheric concentration of SO2 were made over a latitude range 57°S to 70°N. The area sampled included the central and the southern Pacific Ocean and the western section of the United States and Canada. Sulfur dioxide levels averaged 89±69 pptv in the boundary layer and 122±85 pptv in the free troposphere in the northern hemisphere. In the southern hemisphere, SO2 concentrations averaged 57±18 pptv in the boundary layer and 90 ± 21 pptv in the free troposphere. The mean concentration of the continental data was 112±79 pptv in the boundary layer and 160±100 pptv in the free troposphere. The SO2 marine values were 54±19 pptv in the boundary layer and 85±28 pptv in the free troposphere. From a simple chemical model we conclude that a significant amount of background SO2 may originate from the oxidation of OCS.
Atmospheric OCS measurements on Project Gametag
Authors: Torres A. L. , Maroulis P. J. , Goldberg A. B. , Bandy A. R.
Published: February 2008

In the spring of 1978, carbonyl sulfide measurements were made at Drexel University in Philadelphia, Pennsylvania, and on Project Gametag (Global Atmospheric Measurements Experiment of Tropospheric Aerosols and Gases). At Drexel University, measurements were made on 7 days in mid‐March, using a dual‐channel sampling system. These data had a mean concentration and standard deviation of 544±27 pptv on channel 1 and 522±27 pptv on channel 2. In project Gametag, 346 measurements of the tropospheric concentration of OCS were made over a latitude range 57°S to 70°N. Samples were obtained over the central and southern Pacific Ocean and the western sections of the United States and Canada. Overall OCS levels averaged 512 pptv with a standard deviation of 65 pptv and a standard error of the mean of 4 pptv. Carbonyl sulfide levels were statistically the same in the free troposphere and the boundary layer and over continental and marine areas. The apparent north‐south gradient seen in the Gametag data set was attributed to a change in the calibration system as a function of time during the experiment.
Global measurements of aerosols in remote continental and marine regions: Concentrations, size distributions, and optical properties
Authors: Patterson E. M. , Kiang C. S. , Delany A. C. , Wartburg A. F. , Leslie A. C. D. , Huebert B. J.
Published: February 2008

The phase I Gametag (Global Atmospheric Measurements Experiment of Tropospheric Aerosols and Gases) aerosol measurements were designed to provide an initial assessment of the levels, types, and optical effects of tropospheric aerosols in remote marine and continental regions and to examine the possible causal relationships between the observed distributions and the dominant factors controlling aerosol population: chemical and physical transformations, source and sink strengths, and transport. We used size‐number data to determine mass concentrations and to estimate extinction, using nominal optical properties. Filter and impactor data have been used to determine aerosol composition, and correlative aircraft measurements have been used to aid in our data interpretation. Our data have been used to generate latitudinal profiles along our Pacific flight tracks. Our continental measurements, in general, show bimodal aerosol size distributions that reflect different source for each mode. The aerosol population consists primarily of crustal aerosols with r ≥ 0.5 μm and sulfate and combustion aerosols with r < 0.5 μm, with only a minor sea salt component. Owing to vertical mixing, there are no qualitative differences between the boundary layer and the free troposphere. Our data indicate that crustal aerosols represent a significant component of a background tropospheric aerosol in western North America and suggest that the possible contribution of the crustal aerosol to extinction should not be ignored. Pacific marine measurements show a qualitative difference between the boundary layer and the free troposphere. The boundary‐layer aerosol population is dominated by a bimodal sea spray aerosol; optical effects and mass concentration are dominated by a mode with a volume mean radius of ∼1 μm. Our measurements show only a small crustal component of the marine boundary‐layer aerosol. Our data indicate a loss of Cl from the sea spray aerosol, with the greatest loss in the small particles. We have inferred a background concentration of 0.2 ppbm for our measured particles that does not appear to be directly related to the sea spray aerosol. We have identified some of these particles as locally produced secondary aerosols; simultaneous measurements of gaseous species support this interpretation. Our Pacific free tropospheric aerosol measurements show a highly variable aerosol component, with local variations in concentration by 1 order of magnitude within a few kilometers. Our measured total aerosol and crustal component concentrations show a general decrease from north to south. Our lowest mean mid tropospheric concentration was seen south of 20°S; we have identified this mean concentration of 0.08 ppbm as a midtropospheric background aerosol.
Measurements of oxides of nitrogen and nitric acid in clean air
Authors: Kelly T. J. , Stedman D. H. , Ritter J. A. , Harvey R. B.
Published: February 2008

We have measured oxides of nitrogen, nitric acid, and ozone in air at a remote site in the Rocky Mountains west of Boulder, Colorado. The site is infrequently polluted by upslope air movements from the Denver‐Boulder metropolitan area and most often experiences flows of clean air from the west and north. We find NOx (NO + NO2) levels commonly ≈0.2 ppb, with considerable diurnal variation around this mean value, and occasional excursions well below it. Nitric acid (HNO3) levels were <0.03 to 0.1 ppb, and were always smaller than the NOx level. We find the photostationary state equation does not hold in clean air, and we suggest that the deviation from theory may arise from the presence of peroxy radicals.
Radar and acoustic study of lightning
Authors: Holmes C. R. , Szymanski E. W. , Szymanski S. J. , Moore C. B.
Published: February 2008

During 1975 and 1976 an FPS‐18 radar with a 10.9‐cm wavelength was used to study lightning in thunderclouds over Langmuir Laboratory in central New Mexico. The radar antenna beam was pointed at a thundercloud, and then held fixed for extended periods. With this system radar echoes from 156 lightning flashes were detected at altitudes ranging from 5 to 14 km above sea level. About one‐half of the lightning echoes were detected at altitudes greater than 8 km at temperatures less than −20°C. The lightning echoes were strong but transient with durations between 10 and 600 ms. The echo extents along the fixed radar beam ranged from <300 to >2000 m. Most of these echoes rose to peak intensity in less than the 1 ms pulse‐repetition period of the radar and showed fine‐structure fluctuations of the order of 5 to 10 dB with decay time constants of about 2 ms. The durations of the sustained lightning echoes show no correlation with the final echo‐decay times. The electric‐field changes (measured at the Laboratory) that were associated with the lightning echoes observed at the higher altitudes often show a final slow, continuing variation that suggests that continued ionization may extend the echo‐decay time. The thunder produced by the high‐altitude discharges was weak and often was not detected from lightning echoes originating at altitudes greater than 9 km. We infer that the in‐cloud portion of a lightning discharge is a tortuous set of small‐diameter channel elements; that ion‐recombination times are in the order of milliseconds; and that channel temperatures of about 3000°K and electron densities of about 1016 m−3 are often maintained for the duration of the lightning echo by a continuing discharge process.
Characteristics of the Great Whale River plume
Authors: Ingram R. Grant
Published: February 2008

Observations of the motion field and dilution effects associated with the plume of Great Whale River in Hudson Bay are presented for both open water and ice‐covered conditions. In the summer months a distinct plume of about 100 km2 in area is formed offshore which is characterized by a 1–2 m thickness and large velocities directed away from the river mouth in contrast to slower currents parallel to the shore in the ambient waters underneath. Surface drifter results suggest that the outer boundary of plume may be a zone of frontal convergence. Under ice‐covered conditions the plume was significantly thicker and extended much farther offshore in spite of a marked reduction in river runoff at this time.
Semi‐implicit finite element methods applied to the solution of the shallow water equations
Authors: Malone Frank D. , Kuo John T.
Published: February 2008

Semi‐implicit time integration schemes have been combined with finite element space discretization in developing a numerical scheme for the solution of the classical shallow water equations. The principal advantages of this approach are twofold: first, a highly variable gridding capability that allows selective regions of high resolution to be constructed within the computing domain, and second, the use of large time steps chosen on the basis of accuracy rather than by a Courant‐type restriction on their magnitude. The method will be useful in computing the low‐frequency–long wave motions driven by tides and wind on continental shelves and in marginal seas where higher grid resolution is necessary to describe adequately the nearshore dynamics. Application of the methodology is demonstrated by the calculation of the currents and sea surface heights in a hypothetical shelf domain that is driven by a single consituent deep ocean tide.
Some effects of suspended sediment stratification on an oceanic bottom boundary layer
Authors: Adams Charles E. , Weatherly Georges L.
Published: February 2008

A suspended‐sediment‐induced, stably stratified oceanic bottom boundary layer is examined with the Mellor‐Yamada level II turbulence closure model. The boundary layer equations are coupled through the eddy diffusion coefficients for momentum and mass. The bottom boundary layer of the Florida Current is modeled using flow and sediment properties as input parameters. Model results indicate that the boundary layer response to a suspended sediment concentration gradient is to reduce appreciably the level of turbulence. Turbulent kinetic energy and eddy conductivity are reduced by about 40% and 25%, respectively, and bottom stress is reduced by approximately 45%. Increases of veering angle of ≅5°, together with enhancement of the Ekman‐like nature of the current spiral with sediment‐induced stability, are noted. The boundary layer adjusts to the reduced turbulence level by a decrease in the slope of the velocity profile and by diminution of the thicknesses of the boundary layer and contained logarithmic layer by as much as 50%. The predictions are consistent with findings from studies of stably stratified atmospheric boundary layers and sediment‐carrying channel flows. The velocity field near the bottom of a neutrally stratified bottom boundary layer is governed by the relationship U = (u*/κ) ln z/z0. To recover the predicted velocity distribution from this relationship in the sediment‐stratified case, von Karman's constant κ must be reduced by about 15%. The model, however, treats κ as an internal constant. Similarity theory suggests that a more appropriate expression for the near‐bottom velocity field in the sediment‐stratified bottom boundary layer is U = (u*/κ)(ln z/z0 + A ∫Z0z dz/L(z)) where the Monin‐Obukhov length L = z/Rƒ, A = 5.5, and Rf is the flux Richardson number. For the thermally stratified atmospheric boundary layer, L(z) is nearly constant, which yields the familiar log‐linear profile. Our model predicts that in the sediment‐stratified bottom boundary layer, L is nearly linear in z (i.e., Rƒ ≅ const). This yields U ≅ (u*/k′) ln z/Z0, where κ′ = κ/(1 + ARƒ) and κ′ may be interpreted as a modified von Karman constant. The results suggest that u* values inferred from logarithmic speed profiles in sediment‐laden flows may be significant overestimates of the actual u*.
Radiative‐photochemical response of the mesosphere to dynamical forcing
Authors: Frederick John E.
Published: February 2008

Combination of the chemical continuity equation for odd oxygen with the second law of thermodynamics yields analytic solutions which describe the coupled behavior of temperature and ozone perturbations in response to an externally specified forcing. The results appear in a form which allows easy physical interpretation of the coupling between radiative and photochemical processes. When the forcing is chosen to mimic a planetary scale wave, the theory shows that photochemical acceleration of radiative damping reduces the amplitude of the temperature perturbation by an amount which increases with the wave period. Although ozone fluctuations are anti‐correlated with those in temperature, minima in ozone do not coincide exactly in longitude with temperature maxima. The percentage variation in ozone increases upward and is always larger than that in temperature at the same pressure. This demonstrates that variations in ozone on constant pressure surfaces may serve as a sensitive indicator of wave activity in the mesosphere.
Global OH distribution derived from general circulation model fields of ozone and water vapor
Authors: Allam R. J. , Groves K. S. , Tuck A. F.
Published: February 2008

The variability of OH computed with a photochemical steady state model from general circulation model fields of ozone and water vapor is examined. Multivariate regression analysis is used to obtain values of parametric coefficients for the variables upon which the OH field principally depends, and conclusions are drawn about the longitudinal phase relations between these variables for various pressure levels.
Forest vegetation as a sink for atmospheric particulates: Quantitative studies in rain and dry deposition
Authors: Russell Irving J. , Choquette Carl E. , Fang Shih‐Lieh , Dundulis William P. , Pao Andrew A. , Pszenny Alexander A. P.
Published: February 2008

Radionuclides in the atmosphere are associated with nonradioactive air particulates and hence serve to trace the fluxes of air particulates to various surfaces. Natural and artificial radioactivities found in the atmosphere have been measured in vegetation for 10 years to elucidate some of the mechanisms of acquirement by forest trees of atmospheric particulates. Whole tree analysis, in conjunction with soil assay, has served to establish the fraction of the flux of radionuclides retained by above‐ground tissues of a forest stand. Interpretation is facilitated because most radionuclides in the atmosphere are superficially acquired. Typically 5–20% of the total open field flux is retained by the forest canopy in a moderately rainy climate (120 cm/year). Short‐lived daughters of radon give a dry deposition velocity of particulates in the Aitken size range of 0.03–0.05 cm/s, thus permitting an estimate of transient removal by forest canopies by dry deposition of this size fraction.
Concurrent lightning flashes on two television transmission towers
Authors: Kitterman C. Gill
Published: February 2008

A slowly rotating streak camera array was used to photograph lightning flashes to two television transmission towers separated by 1.13 km. In 42 hours of thunderstorm observation the towers were struck by 36 flashes. Eighteen of the flashes occurred in pairs, with a discharge beginning on both towers within an average of about 40 ms. Duration of the two flashes in each pair overlapped, so there was always an interval during which both flashes were in progress. Tendency of the concurrent flashes to group in time, three pairs in 11 min and four pairs in about 1 hour, suggests that unique meteorological conditions may have to prevail for their production. The lack of consecutive flashes separated by intervals of tens or hundreds of milliseconds is consistent with the hypothesis that the second flashes of concurrent pairs may have been triggered by the first.
The collision‐induced linewidths of chlorine and bromine monoxide perturbed by nitrogen
Authors: Doraiswamy S. , Mehrotra S. C.
Published: February 2008

By using the semiclassical, perturbative theory formulated by Mehrotra and Boggs, the J and temperature dependence of line width parameter is computed for ClO‐N2 and BrO‐N2 systems. The temperature dependence is found to be J dependent. As per these calculations the value of the line width parameter for the ClO‐N2 system is at least 35% higher at the temperature T = 300°K, and also the temperature dependence is different from that of the value of Waters et al. However, this disagreement is within the uncertainty range stated by them.
A shallow northeastward current in the North Pacific
Authors: Kenyon Kern E.
Published: February 2008

A permanent large‐scale longitudinal maximum of sea surface temperature at mid‐latitudes in the eastern North Pacific is explained by a permanent circulation. One part of the circulation consists of a northeastward current near the surface, which extends diagonally from low latitudes on the western side to mid‐latitudes on the eastern side of the basin, and a southwestward return flow on either side and underneath the northeastward current. The other part of the circulation consists of mid‐latitude eastward and low latitude westward surface currents. The complete circulation is driven by the wind and by the sun, and it conserves mass and transports heat and eastward angular momentum poleward, as required of the ocean. The seasonal east‐west movement of the longitudinal temperature maximum is explained by the north‐south movement of the diagonal circulation, which follows the seasonal movements of the sun and wind systems. Seasonal variations in the complete circulation are consistent with the balances of mass, heat, and eastward angular momentum being satisfied throughout the seasonal cycle.
On the relationship between the large‐scale property variations and fine structure in the Circumpolar Deep Water
Authors: Georgi Daniel T.
Published: February 2008

Volumetric analysis is used to quantify the observed changes in the Circumpolar Deep Water (CDW) potential temperature/salinity relationship along the axis of the Antarctic Circumpolar Current. A marked increase occurs in the CDW potential temperatures and salinities in the South Atlantic. However, the vertical density distribution is not significantly affected: The volume of water in the deep water density class intervals remains virtually unchanged. Lateral mixing with the warmer and saltier North Atlantic Deep Waters (NADW) and the colder and fresher Antarctic deep waters appears responsible for this change. Temperature and salinity inversions have been observed on continuous salinity‐temperature‐depth soundings in much of the South Atlantic. This fine structure, presumably the signature of lateral mixing and not of internal wave origin, is particularly evident in the southwestern Argentine Basin, where 0.5°C temperature inversions with 50–200 m vertical scales are found at the depth of the NADW/CDW confluence, between 1500 and 2500 m. To quantify the intensity of the fine structure the temperature‐gradient variance in the 32–256 m vertical wavelength band is calculated for data from the southwest Argentine Basin the Drake Passage, Scotia Sea, the central and eastern Atlantic, and the southwest Indian Ocean. The largest variance levels occur in the Argentine Basin, the smallest in the Drake Passage, while those in the central Atlantic are intermediate. The temperature‐gradient variance data from the Argentine Basin are then used to estimate the lateral temperature flux in the NADW/CDW confluence with a statistical model developed by Joyce (1977). The calculated quantities are small; the lateral temperature flux is of the order of 4 × 10−4°C m s−1 and the lateral diffusivity of order 40 m2 s−1. The data are also used to calculate heat flux divergences. The close agreement between the heat flux divergence calculated from the temperature changes of the CDW core and the divergence calculated with the fine structure data suggest that lateral mixing accounts for the large‐scale property changes observed in the CDW core.
Balloon‐borne measurements of the small ion concentration
Authors: Rosen J. M. , Hofmann D. J.
Published: February 2008

Balloon‐borne measurements of the small ion concentration were made using a Gerdien condenser. The instrument differs from others in that a lobe pump was used to draw air through the ion collector thus insuring a well‐known and constant flow rate. The profiles were found to be quite repeatable over a 2‐year period (1977–1979). In contrast to previous data the new profiles are much smoother and show only a small decline in concentration above the ion density maximum. It is believed that this discrepancy can be attributed to a poorly known and variable flow rate in the older instruments.
Observations of clear air turbulence and winds with the Millstone Hill radar
Authors: Watkins B. J. , Wand R. H.
Published: February 2008

The Millstone Hill 440 MHz radar at Westford, Massachusetts, has been upgraded for studies of turbulence and winds in the troposphere and lower stratosphere. Useful data have been obtained up to 20 km altitude. The radar has been operated with a peak pulse power of 1–1.5 MW, a pulse length of 10 μs and a pulse repetition of 500 Hz. The 150‐foot diameter steerable antenna has been used differently in three types of experiments, (1) Antenna azimuth scans with fixed elevation, (2) elevation scan with fixed azimuth, and (3) fixed antenna. Azimuth scan experiments can obtain both the horizontal and the vertical wind components. Antenna elevation scans have been used to investigate the horizontal structure of turbulence. The fixed antenna experiments provide maximum time resolution and are useful for studying the occurrence of waves. Waves in both the velocity and Cn2, the refractive index turbulence structure constant, have been frequently observed at heights near the tropopause and below. The waves have periods 10–20 min and have been interpreted as internal gravity waves. The largest amplitude waves have been found to occur (1–2 km) below the level of a velocity shear. Waves generally persist for several cycles. By using the antenna elevation scan method, the level of turbulence (as measured by the Cn2 value) has been measured at points separated by 10–20 km. Horizontal patches of turbulence have been found that appear to move with the wind.
Dynamical regime of the lower thermosphere over east Siberia
Authors: Kazimirovsky E. S.
Published: February 2008

Some main results of experimental investigations of the dynamical regime of the lower thermosphere over east Siberia (85–95 km) are presented. Regular measurements of horizontal ionospheric drifts by the radio‐physical method of closely spaced receivers by using a long wavelength transmitter operating at a frequency of 200 kHz have been carried out near Irkutsk during 1975–1979. The seasonal and interannual variations of the prevailing wind (zonal and meridional), and amplitudes and phases of semidiurnal tides, are investigated. Planetary waves with periods of 1–30 days and internal gravity waves with periods of 20–80 min are found in the wind field. Comparison with results of analogous measurements in central Europe reveals a longitudinal effect on the dynamical regime of the mid‐latitude lower thermosphere.
Long‐term variations in the stratosphere of the northern hemisphere during the last two sunspot cycles
Authors: Naujokat Barbara
Published: February 2008

Stratospheric geopotential height and temperature data of three levels are examined for the period 1957–1979. By using a low‐pass filter for each time series at a 10°‐by‐10° latitude‐longitude grid, longterm variations over the northern hemisphere are obtained, whose amplitudes and phases depend on latitude and longitude as well as on the height level. Analyses of differences between sunspot maximum and minimum are made, looking for a possible solar relationship. It cannot be proved that convincing statistical evidence exists for such relationships because of the few degrees of freedom in the highly autocorrelated data series. However, these hemispheric analyses are presented in the hope that they may help lead to an understanding of relations, if they do exist, that can be supported on physical, rather than statistical, grounds.
Global ozone long‐term trends from satellite measurements and the response to solar activity variations
Authors: Keating G. M. , Lake L. R. , Nicholson J. Y. , Natarajan M.
Published: February 2008

Analysis of global ozone variations for the period April 1970 to December 1975 was performed by using the reprocessed Nimbus 4 backscattered ultraviolet (BUV) measurements of total ozone. A correlation coefficient of 0.97 is found between the 6‐month running mean of global mean total ozone (filtered for mean semiannual, annual, and quasibiennial variations) and the 10.7‐cm solar activity index. Correcting ozone for a time‐dependent latitudinal bias relative to Dobson ozone measurements reduces to 2–3% the global mean ozone variation over the solar cycle. The solar ultraviolet variability required in a one‐dimensional time‐dependent radiative photochemical model to account for the observed ozone variation appears to be consistent with recent solar UV observations.
Stratospheric observations of the attenuated solar irradiance in the Schumann‐Runge band absorption region of molecular oxygen
Authors: Frederick J. E. , Hudson R. D. , Mentall J. E.
Published: February 2008

A spectrometer flown on the first Solar Absorption Balloon Experiment (SABE‐1) observed the attenuated solar irradiance between 184 and 202 nm from an altitude near 40 km. These measurements provide a check on the absorption cross sections of molecular oxygen in the spectral region of the Schumann Runge bands. Comparison of the measurements with calculations based on cross sections derived from laboratory data shows a general agreement although the irradiance measurements have large error bars near the centers of the absorption bands. The results imply that the 184–200 nm solar irradiance that penetrates to the stratosphere can be computed to an accuracy of ±30% or better by using presently available cross sections.
OCS photolysis and absorption in the 200‐ to 300‐nm region
Authors: Rudolph R. Neil , Inn Edward C. Y.
Published: February 2008

A continuum source with three different interference filters and two different monochromatic sources were used to photolyze OCS in the region from 200 nm to 300 nm. The total quantum yield for the production of CO was measured, and the results indicate a primary quantum yield of 0.72±0.08. Absorption cross sections for OCS measured at 0.5‐nm intervals are reported as well as the percent change in absorption upon cooling to 195°K. The structured features in the absorption are reinvestigated and discussed.
An energetics total load sediment transport model for a plane sloping beach
Authors: Bailard James A.
Published: February 2008

Bagnold's energetics‐based total load sediment transport model for streams is used as a basis for the development of a total load model of time varying sediment transport over a plane sloping bed. In both the bedload and suspended load, the transport rate vectors are found to be composed of a velocity‐induced component directed parallel to the instantaneous velocity vector and a gravity‐induced component directed down slope. The model is applied to idealized surfzone conditions, leading to estimates of the local longshore and onshore‐offshore sediment transport rates as well as the equilibrium beach slope as a function of the local wave and current conditions. The model is combined with a nonlinear longshore current model and spatially integrated to obtain predictions of the total longshore transport rate as a function of the incident wave conditions. The results support the general form of the wave power equation except that the wave power coefficient is no longer constant but is instead a complex function of the incident wave and beach characteristics.
Calculating the oceanic CO2 increase: A need for caution
Authors: Shiller Alan M.
Published: February 2008

A number of workers have presented calculations attempting to show the anthropogenic CO2 increase in the ocean. These workers back‐calculate the CO2 concentration of a water parcel to when it was at the sea surface by using well‐known ratios to correct for chemical changes induced by biological decomposition. Because of the potential significance of these CO2 back‐calculations, their limitations are examined here. In the Antarctic Intermediate Water, which has served as a primary testing ground for these backcalculation models, mixing is seen to significantly alter chemical concentrations. However, previously used mixing corrections are shown to have little effect on an analogous back‐calculation of preformed nitrate. Additionally, the results of the CO2 back‐calculations are probably too high for the water mass in question. Thus the ability of these methods to provide reliable estimates of the oceanic CO2 increase is in doubt.
Rocket measurements of the distribution of water vapor in the stratosphere at high latitudes
Authors: O'Brien R. S. , Evans W. F. J.
Published: February 2008

Two measurements of the altitude distribution of stratospheric water vapor have been made with a rocket‐borne infrared photometer, which measures long path atmospheric absorption of the solar beam in the 2.7‐μm spectral region. The photometer was flown from Cape, Parry, Canada (latitude 70.2°N, longitude 124.6°W), on December 6, 1974, and from Kiruna, Sweden (latitude 67.9°N, longitude 21.1°E), on March 13, 1975, at sunset. These measurements indicate that the water vapor mixing ratio increases from approximately 1.5 ppmv at the tropopause to approximately 8 ppmv at 50 km and then decreases at higher altitudes. These features are consistent with current theoretical considerations of the stratospheric water vapor distribution and with the results of other experimental investigations. A source region from methane oxidation at higher altitudes and a sink near the tropopause are suggested. A computer simulation of laboratory measurements indicated that the wings of the water vapor lines in the 2.7‐μm region are super‐Lorentzian. This super‐Lorentzian behavior of the line wings was incorporated in the analysis of the atmospheric measurements.
A note on the observed diurnal and semidiurnal rainfall variations
Authors: Hamilton Kevin
Published: February 2008

Earlier investigations of the diurnal and semidiurnal rainfall variations are extended with an analysis of hourly rainfall data at 735 stations in the United States and Puerto Rico. Interesting findings include a confirmation of the remarkable tendency (observed earlier by Lindzen (1978) and Hamilton (1981)) for the semidiurnal component of tropical rainfall to peak at roughly 0330 (and 1530) LT. It also appears that (at least over the United States) this 0330 phase (or one slightly later) is quite typical of the midlatitude region as well. The significance of these findings for the theory of the semidiurnal atmospheric tide is discussed.
Global lightning distributions at dawn and dusk
Authors: Turman B. N. , Edgar B. C.
Published: February 2008

Global lightning distributions for the period August 1977 to June 1978 have been obtained from lightning sensors on Defense Meteorological Satellite Program (DMSP) flights 2 and 3. Seasonally averaged trigger rates are calculated for 10°×10° cells on the earth, an area roughly equal to the resolution limit of the sensors. These data indicate that 37% of global lightning activity originates over the oceans at dawn, and this fraction drops to 15% at dusk. The seasonally averaged mean global lightning flash rate varies by about 10% through the year, with an absolute value within the range of 40–120 flashes per second.
Results of an international workshop on atmospheric electrical measurements
Authors: Rosen J. M. , Hofmann D. J. , Gringel W. , Berlinski J. , Michnowski S. , Morita Y. , Ogawa T. , Olson D.
Published: February 2008

An Atmospheric Electrical Measurements Workshop was conducted at the University of Wyoming in which balloon borne comparisons of ionization, conductivity, ion density, air‐earth current, and electric field measurements were made. After some deliberation there now appears to be relatively good agreement between the various experimental groups with a major exception being the ion density measurements. The source of this discrepancy is perhaps the poorly defined flow rate through some types of ion counters. Another important experimental result indicates that the direct measurements of air‐earth current are almost exactly one half the value calculated from the total conductivity and electric field profiles. The values of the small ion mobility calculated from the workshop data suggest a relatively constant value to about 30 km, the maximum altitude of the soundings.
Lead precipitation fluxes at tropical oceanic sites determined from 210Pb measurements
Authors: Settle D. M. , Patterson C. C. , Turekian K. K. , Cochran J. K.
Published: February 2008

Concentrations of lead, 210Pb, and 210Po were measured in rain selected for least influence by local sources of contamination at several tropical and subtropical islands (Enewetak; Pigeon Key, Florida; and American Samoa) and shipboard stations (near Bermuda and Tahiti). Ratios expressed as ng Pb/dpm 210Pb in rain were 250–900 for Pigeon Key (assuming 12% adsorption for 210Pb and no adsorption for lead), depending on whether the air masses containing the analyzed rain came from the Caribbean or from the continent, respectively; about 390 for the northern Sargasso Sea downwind from emissions of industrial lead in North America; 65 for Enewetak, remote from continental emissions of industrial lead in the northern hemisphere; and 14 near Tahiti, a remote location in the southern hemisphere where industrial lead emissions to the atmosphere are much less than in the northern hemisphere. (The American Samoa sample yielded a higher ratio than Tahiti; the reason for this is not clear but may be due to local Pb sources.) The corresponding fluxes of lead to the oceans, based on measured or modeled 210Pb precipitation fluxes, are about 4 ng Pb/cm2y for Tahiti, 10 for Enewetak, and 270 for the Sargasso Sea site, and between 110 to 390 at Pigeon Key.
Coastal ocean current response to storm winds
Authors: Gordon R. L.
Published: February 2008

Design of offshore structures requires knowledge of the appropriate current profile to be used in conjunction with the design wave. Accurate determination of the current profile will depend on reliable current models. Vertical transfer of momentum in storm‐driven current models is commonly treated either by using eddy viscosity or by assuming ‘slab‐like’ mixed layer flow. These two fundamentally different approaches predict different current speeds and profiles during severe storms. The existing data base is inadequate to determine which approach is better, but most existing data sets are subject to one or more of four limitations that can lead one improperly to interpret the data as supporting the existence of current velocity shear in otherwise uniform mixed layers. One‐dimensional slab models are found to compare favorably with observed wind‐driven currents at the Ocean Test Structure in the Gulf of Mexico (deployed in 20 m deep water). By using some reasonably simple assumptions, these slab models are able to replicate many of the significant features of a wide range of different responses. The character of the response appears to depend on an interaction of stratification and topography. Barotropic responses are characteristic of typical coastal responses; currents are oriented longshore and are in phase with the wind. Baroclinic responses are dominantly inertial as might be expected in the deep sea, but with an additional near‐bottom cross‐shore counter flow. The structure of one observed barotropic response is compared in detail to predictions of both slab and eddy viscosity models and found consistent with a slab model and inconsistent with eddy viscosity models. Shear observed during this event was not significantly different from zero, but was significantly below estimated shear predictions of four eddy viscosity models given the peak 0.4 N/m2 wind stress.