bluuebunny/crossref_metadata_2025 huggingface dataset:
Plane with protrusions as an atmospheric boundary
Authors: Otterman J.
Published: February 2008

A plane with protrusions is analyzed as a model for remote sensing of the earth's surface and for absorption of solar irradiance at the surface. The model is aimed at representing arid regions where plants form isolated clumps with large interstices of bare soil. The protrusions (plants) are regarded as thin vertical cylinders, and the key parameter s (which is dimensionless) is the sum of vertical cross sections of protrusions over a unit area. Remote sensing from a satellite indicates the plausibility of the model, inasmuch as the model closely reproduces, as a function of the solar zenith angle, the spectral reflectivities measured by LANDSAT over an arid steppe. The explicit expressions for the hemispheric reflectivities indicate a strong dependence of the surface reflectivity of such terrain on the zenith angle. The heating of the protrusions is a very significant part of the daily total surface heating when the noon sun is low. The interactions with the atmosphere are generally different for the protrusions and for the planar surface of the soil. The difference in the interactions is especially pronounced in the arid steppe, inasmuch as the effective thermal inertia of the protrusions (mostly dry bushes) in heat transfer to the atmosphere is very low. This low thermal inertia, and therefore nearly immediate transfer to the atmosphere of the solar irradiance absorbed by the protrusions, is indicated by radiation temperature measurements of the protrusions and of the soil.
Further study of a jet stream‐generated Kelvin‐Helmholtz instability
Authors: Klostermeyer J. , Rüster R.
Published: February 2008

High‐resolution VHF Doppler radar measurements during a jet stream passage reveal radial velocity oscillations produced by a Kelvin‐Helmholtz (KH) instability. A detailed investigation of the velocity data, using digital filters and least squares methods, shows that the growth rate of the KH oscillations decreases linearly with increasing time so that a growth and a decay stage can be defined. During the occurrence of the KHI, the radar signal power is characterized by periodic bursts up to 20 dB above the mean power level. The bursts have a period equal to that of the KH oscillation and are restricted to heights around the critical level at which the KH instability is generated. Model computations indicate that the power bursts are produced by static instabilities which are due to KH‐induced superadiabatic lapse rates. During the growth stage, the vertical profile of the mean wind exhibits characteristic temporal changes that can probably be ascribed to the Reynolds stress of the KH instability. There is some evidence that the observed KH oscillations are parts of a sequence of KH waves initiated by long‐period gravity waves.
Flexural waves in the Ross Ice Shelf
Authors: Williams R. T. , Robinson E. S.
Published: February 2008

Flexural waves related to the ocean swell are identified more than 600 km from the open sea in the Ross Ice Shelf, Antarctica, where the ice cover is in places more than 500 m thick. An equation relating the power spectra of the flexural wave and the ocean swell is derived, based on the continuity of pressure in the fluid layer across the ice front. Correcting for the effect of the ice, the power spectrum of the wave in the ice compares to that of the ocean swell elsewhere in the Pacific Ocean.
Observations of surface and bottom currents in the Beaufort Sea near Prudhoe Bay, Alaska
Authors: Matthews J. B.
Published: February 2008

Surface drifters have been released in the Beaufort Sea near Prudhoe Bay for three consecutive years: 1977, 1978, and 1979. Two releases were made after the shorefast ice had broken up, and one release was made just prior to breakup. All drifter recoveries suggest that the movements result from prevailing wind‐driven currents during the open water season although there are small currents under the ice in winter which probably contribute to the observed movements. Drifters released just before a large storm traveled the greatest distances (335 km) in the shortest time (40 days) with mean velocities close to 10 cm/s. These travel times and computed speeds are consistent with values of 3% of the wind transport over the same period. The statistics of drifter recoveries are comparable to those for coastal regions in North America despite the very sparse population along the arctic coast. For the under‐ice releases, there was a consistent shoreward movement even for drifters released as far as 10 km offshore, indicated by the recovery data. This result suggests that oil released under ice in winter would tend to move shoreward. Subsequently, oil patches would be wind driven after spring breakup of the land‐fast ice.
Diurnal variations of mesospheric ozone using millimeter‐wave measurements
Authors: Wilson W. J. , Schwartz P. R.
Published: February 2008

In March 1979, millimeter‐wave observations of the ozone emission line at 101737 MHz were made to measure the diurnal variations in mesospheric ozone. Changes in mesospheric ozone were measured diurnally for a 10‐day period. The ozone column above ∼76 km rapidly decreased after sunrise to half value within 1 hour and was then followed by a slower (∼8 hours) decrease to an absolute minimum at 1600 hours. At sunset, the ozone column above ∼76 km increased rapidly to its maximum value within 2 hours. In the 48–68 km altitude range, the ozone changes were gradual with a minimum near local noon (1200 hours).
Estimating surface wind direction over drifting open pack ice
Authors: Feldman Uri , Howarth Philip J. , Davies John A.
Published: February 2008

Surface wind direction data, vital for the study of drifting pack ice, are not routinely available for polar oceans. These data may be estimated from the difference between the direction of motion of detached ice floes, as determined from sequential satellite images, and the angle of sea ice deflection, which varies with the geostrophic wind speed.
Repeatability and measurement uncertainty of the United States meteorological rocketsonde
Authors: Schmidlin Francis J.
Published: February 2008

Remote temperature measurements from satellites are currently validated by using rocketsonde and radiosonde data. The reliability of the validation is directly dependent upon how well these measurements and those from the satellites represent the atmosphere. Past experience indicates that remote and in situ mean temperatures usually agree within a few degrees, while agreement between individual observations is not as good. It has been suggested that this may be due to atmospheric variability observed by the rocketsonde and radiosonde techniques but unresolved by the satellite. This observed variability, especially when measurements are obtained close in time and space, is of particular concern since this raises the question whether the variability is due to natural atmospheric change or arises from instrumental instabilities. It is shown that the U.S. rocketsonde, the Super Loki Datasonde, provides reliable temperature measurements to about 1°C. A sample of measurements obtained close together in time is analyzed to provide this estimate. It is important that the Middle Atmosphere Program (MAP) take advantage of the rocketsonde's measurement capability not only to validate remote measurements but to obtain detailed measurements of localized phenomena in the middle atmosphere.
Winds and waves (10 min‐30 days) in the mesosphere and lower thermosphere at Saskatoon (52°N, 107°W, L = 4.3) during the year, October 1979 to July 1980
Authors: Manson A. H. , Meek C. E. , Gregory J. B.
Published: February 2008

Winds from a medium frequency (2.2 MHz) radar, operating as a partial reflection drifts system, have been obtained for four seasons of 1979/1980. Harmonic and spectral analyses have been used to provide monthly profiles of zonal and meridional winds, and the amplitudes and phases of 12 and 24 hour tides, at heights from 70 to 110 km. There are distinctive changes in tidal vertical wavelengths and phases between winter‐ and summer‐like months. Fluctuations of the mean daily wind and the tides during the stratwarm of February 1980 are documented. Oscillation of the wind, for all seasons, with periods from 2 to 30 days, are related to Rossby periods for atmospheric normal modes. Energy densities for oscillations appropriate to waves ranging in scale from gravity, through tidal, to planetary waves are evaluated by month and are compared with turbulence parameters for energy dissipation rates and vertical eddy diffusion coefficients. There are winter maxima and summer secondary maxima in both energy densities and turbulence parameters, which suggest a relationship between certain waves and the creation of turbulence.
Measurements of CO and CH4 in the troposphere over Saudi Arabia, India, and the Arabian Sea during the 1979 international summer monsoon experiment (MONEX)
Authors: Newell Reginald E. , Condon Estelle P. , Reichle Henry G.
Published: February 2008

During the 1979 Summer MONEX, 150 air samples collected over Saudi Arabia, India, and the Arabian Sea were analyzed for CO and CH4. Near Dhahran and over the Ganges Valley there were high concentrations of CO, around 300 ppbv, in the boundary layer. Out over the Saudi Arabian desert there was no sharp increase in the boundary layer. It is suggested that these high concentrations originate from pollution sources. Low values of CO, down to 80 ppbv, are found over the Arabian Sea as the monsoon progresses, and these may originate from the southern hemisphere. Methane over Saudi Arabia (1.59 ppmv) is a little higher than that over the Arabian Sea (1.54 ppmv) probably because the latter region is influenced by air from the southern hemisphere.
The solar irradiance from 200 to 330 nm
Authors: Mentall J. E. , Frederick J. E. , Herman J. R.
Published: February 2008

The full disk solar spectrum over the wavelength range 200–330 nm has been measured with a spectral resolution of 0.12 nm. The measurement was performed by using a double monochromator pointed at the sun from a high altitude parachute. Only small corrections were required to account for atmospheric absorption. Good agreement was obtained with previously reported measurements.
Analysis of linear and nonlinear inversion of optical data for a micrometeorological temperature profile
Authors: Mach William H.
Published: February 2008

The practical inversion of optical data for a micrometeorological temperature profile requires a nonlinear inversion of a system of polynomial equations. A method of nonlinear least squares can produce a physically acceptable solution of this nonlinear inversion problem. Because this method, which is demonstrated with the inversion of simulated optical data, does not produce an unique solution, the images of targets are calculated and used to examine the solution. A solution of the nonlinear inversion problem is physically acceptable when these calculated images agree with an independent set of simulated images to within expected errors of measurement. The nonlinear inversion of optical data contaminated with errors is shown not to be a difficult problem, because the numerical method of inversion is designed to find efficiently the coefficients used to represent the temperature profile. The geometric properties of the equations used in the method of inversion are compared for a linear and nonlinear inversion of optical data.
Ocean frontal formation due to shallow water cooling effects as observed by satellite and simulated by a numerical model
Authors: Garwood Roland W. , Fett Robert W. , Rabe Kevin M. , Brandli Henry W.
Published: February 2008

During the winter season, infrared data from meteorological satellites reveal the outline of the Little Bahama Bank and the Great Bahama Bank as cold areas conforming almost precisely to the bathymetry as outlined by the 20 m contour line. During the summer season the effect is reversed and the Banks appear as warm areas, distinct from the deeper water that surrounds them. This paper investigates the winter season phenomena by using a one‐dimensional numerical model to calculate the heat and salt budgets for a variety of atmospheric scenarios including a sudden air temperature drop over the banks as a result of cold frontal passage. It is found that such an event results in shallow water cooling producing distinct temperature fronts and mild salinity fronts. Increased wind speed, under low humidity conditions, maximizes the effect.
On the dynamics of the ice sheets
Authors: Halfar P.
Published: February 2008

A similarity solution of the equation that describes the time evolution of an ice sheet is obtained by separation of variables. It describes the motion of an initial δ function ice sheet distribution and is asymptotically stable with respect to all perturbations that leave the total volume invariant. Homogeneity in one horizontal direction is assumed.
Steady state spectral density of gravity‐capillary waves
Authors: West Bruce J.
Published: February 2008

The linear coupling model of Miles and Phillips for the air‐sea interaction is generalized to include the average effect of the nonlinear interactions in the dynamic equations for the gravity‐capillary waves. The linearized dynamic equations are stochastic with solutions that have stable moments. In particular, a steady state power spectral density for the water wave field is calculated exactly in the context of the model for various wind speeds.
The influence of corona space charge on a direct measurement of atmospheric potential
Authors: Willett John C.
Published: February 2008

The error introduced into a tethered‐balloon measurement of the atmospheric potential by the plume of space charge drifting downwind from the conducting tether is analyzed. A number of simplifying assumptions yield a mathematically tractable model capable of placing an upper bound on the relative magnitude of this error in terms of the height achieved by the balloon. Relaxing the most severe of these assumptions allows more realistic error estimates at the expense of some loss of rigor. It is concluded that an altitude of between one and two conductivity scale heights is sufficient to reduce the error below 10%.
Model spectrum of magnetic induction caused by ambient internal waves
Authors: Petersen Robert A. , Poehls Kenneth A.
Published: February 2008

Internal waves propagating in electrically conductive seawater induce weak secondary magnetic fields in the presence of the earth's magnetic field. The two‐dimensional (frequency and wave number) magnetic induction spectrum caused by ambient internal waves is estimated by using the Garrett and Munk model spectrum of ocean internal waves. Because it involves convolution integrals over depth, the magnetic induction model spectrum depends on good estimates of the vertical coherence of internal wave motion. It is demonstrated that the vertical coherence scaling predicted by the Garrett and Munk model shows adequate agreement with field measurements. The predicted power spectral levels of magnetic induction are sufficiently large that magnetometry is a potentially useful oceanographic tool.
Gas exchange dependency on diffusion coefficient: Direct 222Rn and 3He comparisons in a small lake
Authors: Torgersen T. , Mathieu Guy , Hesslein R. H. , Broecker W. S.
Published: February 2008

A direct field comparison was conducted to determine the dependency of gas exchange coefficient (kx) on the diffusion coefficient (Dx). The study also sought to confirm the enhanced vertical exchange properties of limnocorrals and similar enclosures. Gas exchange coefficients for 222Rn and 3He were determined in a small northern Ontario lake, using a 226Ra and 3H spike to gain the necessary precision. The results indicate that the gas exchange coefficient is functionally dependent on the diffusion coefficient raised to the 1.22+ > 12−35 power (kx = ƒ(Dx1.22)), clearly supporting the stagnant film model of gas exchange. Limnocorrals were found to have gas exchange rates up to 1.7 times higher than the whole lake in spite of the observation of more calm surface conditions in the corral than in the open lake.
Total ozone‐solar activity relationship
Authors: Reber C. A. , Huang F. T.
Published: February 2008

Nearly 6 years of global ozone monthly mean data from the Nimbus 4 BUV instrument are compared with monthly values of solar activity using 10.7‐cm flux (F(10.7)) as a parameter. Several techniques are explored in calculating the correlation between the two data sets, and all yield relatively high correlations, ranging from R = 0.68 for ‘raw’ monthly means to 0.94 using a 6‐month running mean for each data set. It is shown, however, that the bulk of the correlation is due to the long‐term decreasing trends in both data sets. When the long‐term trends are removed, a cross‐correlation analysis produces a maximum with no phase shift or with the ozone variations leading the solar variations by 1 month, thus reducing the likelihood of a cause and effect relationship on time scales of this order. Considering the current uncertainty in the long‐term stability of the BUV instrument, and the resulting uncertainty in any long‐term trend derived from its data, it is unrealistic to draw firm conclusions about a solar cycle influence on total ozone from this satellite data set.
Gulf of Cadiz water observed in a thermocline eddy in the western North Atlantic
Authors: Zantopp Rainer , Leaman Kevin
Published: February 2008

The observation of an isolated lens with a layer of constant temperature, salinity, and density within the upper thermocline of the southwestern Sargasso Sea is reported. Temperature and salinity as well as a high oxygen content indicate the Gulf of Cadiz as the area of formation. The age of the lens appears to be 3–4 years. Atmospheric conditions are favorable for deep convection in the Gulf of Cadiz during winter months, but no dramatic event could be detected. The hydrographic and dynamic background of the lens in the Antilles Current area is discussed with reference to Iselin's (1936) standard data.
On the sea level forcing of the Mid‐Atlantic Bight
Authors: Hopkins T. S.
Published: February 2008

The Mid‐Atlantic Bight circulation is discussed with particular comment directed toward the role of the parabathic pressure gradient. A distinction is made between external and local sea level forcing. External forcing consists of an oceanic boundary condition on the sea level gradient. The shelf response to this is geostrophic: the diabathic component drives the parabathic flow, and the parabathic component drives diabathic flow. The latter, together with the bottom stress generated by the former and the physical dimensions of the shelf, determine the degree of convergence or divergence within the shelf volume, which, in turn, determines the sea level dependence required to satisfy continuity over the shelf. Local forcing due to the wind stress, the internal field of mass, and the total bottom stress, in conjunction with local bathymetry, determines the extent of local convergence or divergence, and as a consequence, generates additional sea level distortion. Conceptually, local and external forcing can be considered as independent although they are, in fact, coupled through bottom stress and internal field of mass adjustment.
Response of Florida Atlantic shelf waters to Hurricane David
Authors: Smith Ned P.
Published: February 2008

Water level data, bottom pressures and temperature, and current records are used to document the response to Hurricane David of inner and middle shelf waters along the Atlantic coast of Florida near latitude 27°30′N. Available data records extend from well before the storm to well after its passage on September 3, 1979, to put hurricane effects in proper perspective. Highest water levels recorded in the Fort Pierce Inlet nearby indicate values about 60 cm above normal high water levels. Bottoms pressure fluctuations corrected for atmospheric pressure variations suggest a storm surge over the inner shelf of approximately 100 cm above the normal high water mark. Longshore current components over both the inner and the middle shelf rise briefly to about twice the normal maximum speeds. A distinct upwelling event is recorded in both inner and middle shelf waters as the storm moved through the study area. Near‐bottom temperatures along the 10‐ and 26‐m isobaths decrease to just under 17°C and 9°C, respectively, and remain low for a period of about a week. Temperature variations in near‐surface waters over the middle shelf are dominated by near‐inertial period internal wave activity and hurricane effects are negligible. Data suggest that hurricane effects in the hydrographic variables were apparent for only 1–2 weeks following the passage of a storm.
The temperature dependence of the rate constant for the reaction of hydroxyl radicals With nitric acid
Authors: Kurylo Michael J. , Cornett Kenneth D. , Murphy Jennifer L.
Published: February 2008

The flash photolysis resonance fluorescence technique has been used to measure the rate constant for the reaction
products over the temperature range 225–443 K. The data below room temperature can be fit to the expression k1 = (1.05±0.40) × 1014 exp [(759±100)/T] cm3 molec−1 S−1. This equation, however, markedly underestimates the values of k1 above 300 K. An interpretation of the behavior is presented, and implications of these values for k1 on stratospheric reaction cycles are discussed.
Aircraft sampling of the sulfate layer near the tropopause following the eruption of Mount St. Helens
Authors: Lezberg Erwin A. , Otterson Dumas A. , Roberts William K. , Papathakos Leonidas C.
Published: February 2008

Twenty‐three filter sampling flights of the NASA Lewis F‐106 aircraft, were conducted in the Great Lakes region between June 4 and December 23, 1980, following the major eruption of Mount St. Helens (Washington State) on May 18. The IPC‐1478 filters were exposed over an altitude range spanning the local tropopause. A filter sample exposed above the tropopause on June 5 indicated a sulfate level of 50 times the baseline measurements, which is consistent with the trajectory predictions of the leading edge of the cloud on its second transit around the earth. Subsequent measurements over a period of 7 months revealed the existence of a layer of sulfate above the tropopause that decayed to a level of about 4 times previously measured background levels by the beginning of August. Concentration of nitrate above the tropopause exhibited considerable variability and showed some enhancement compared with previously measured concentration levels. On the basis of the null results of X ray fluorescence measurements, there is no evidence of ash particle concentrations >3.4 μm/m3 persisting in the layer above the tropopause following the second transit of the cloud.
Transient radiative influences of cumulus clouds on surface temperature and fluxes
Authors: Bradley S. G.
Published: February 2008

Diurnal or static solutions are usually considered for radiative forcing of surface temperature. In this paper, short‐time solutions, applicable to radiative transients caused by cloud motion, are described for both land and ocean surfaces. The short‐time approximation predicts surface temperature changes independent of sensible and latent heat fluxes. The theory suggests the ocean skin temperature will have a response shorter than 10 s and so will follow changes in downward longwave flux. The theory is supported by results from airborne remote radiation measurements beneath clouds. Over the land deduced thermal inertia values agree closely with those predicted from geological data. Oceanic observations allow a viscous layer thickness to be estimated which is in agreement with previous direct findings. Measured temperature excursions demonstrate that cloud‐related radiative forcing is significant and should be considered in boundary layer models which incorporate clouds.
Power plant induced rainfall modification: Field studies and nonparametric tests
Authors: Patrinos A. A. N. , Miller R. L. , Saylor R. E.
Published: February 2008

The results from the first 18 months of a field study of power plant induced rainfall modification are presented. This study, a part of the Meteorological Effects of Thermal Energy Releases (METER) Program, employs a network of 49 recording raingages and four recording windsets situated around the Bowen Electric Generating Plant in northwestern Georgia. The results are based on the data from the period February 1978 to August 1979. The analysis was based on a nonparametric statistical approach and primarily compared medians and dispersions of rainfall distributions. The comparisons were performed in a control‐target framework, and the data were stratified according to various storm types. The tests failed, in most cases, to detect an effect. The risk of concluding an effect when in fact there is none was 5%.
Ionospheric correction for SEASAT altimeter height measurement
Authors: Lorell Jack , Colquitt Elodie , Anderle Richard J.
Published: February 2008

The ionosphere effect on signal speed, and hence on the SEASAT radar altimeter measurement, is directly proportional to the columnar electron content of the ionosphere. This paper contains a description of the Faraday rotation technique used by the SEASAT project to measure the ionosphere and of the mapping scheme used to map the measurements to the spacecraft location. In addition, it describes the evaluation procedure used for validation and accuracy assessment.
SEASAT altimeter timing bias estimation
Authors: Marsh J. G. , Williamson R. G.
Published: February 2008

The calibration of the altimeter observation time tags to the millisecond level of accuracy is fundamental to the processing of the data. Initial analyses of the SEASAT altimeter data indicated the presence of a time calibration bias which produced altimeter measurement errors in excess of a meter. A technique has been developed for the solution of the time tag bias based upon the analysis of sea surface height discrepancies at ground track intersections. This technique has permitted very good separation of the dominant once per revolution ephemeris error, which amounts to about 1.5 m rms, from the timing error signature. Furthermore, the technique does not depend upon the availability of precise geoid data. The application of this technique to a global set of SEASAT altimeter data covering the time period of July 28–August 9, 1978, has resulted in a value of −81.0±2 ms for the time tag bias. This value agrees to within 2.9 ms of the value derived at the University of Texas from a similar analysis of the altimeter data. Furthermore, these values corroborate the revised value of −79.4 ms derived at NASA/Wallops Flight Center and the Johns Hopkins University/Applied Physics Lab from a reexamination of the internal instrument time delays. The modeling of oceanic tides and the orbit computations are the major error sources in these analyses.
Comparison data for SEASAT altimetry in the western North Atlantic
Authors: Cheney Robert E.
Published: February 2008

The radar altimeter flown on SEASAT in 1978 collected approximately 1000 orbits of high‐quality data (5–8 cm precision). In the western North Atlantic these data have been combined with a detailed gravimetric geoid in an attempt to produce profiles of dynamic topography. In order to provide a basis for evaluation of these profiles, available oceanographic observations in the Gulf Stream/Sargasso Sea region have been compiled into a series of biweekly maps. The data include XBT's, satellite infrared imagery, and selected trajectories of surface drifters and subsurface SOFAR floats. The maps document the known locations of the Gulf Stream, cyclonic and anticyclonic rings, and mid‐ocean eddies during the period July–October 1978.
Modification of the surface elevation probability distribution in ocean swell by nonlinear spectral broadening
Authors: Janssen Peter A. E. M. , Komen Gerbrand J.
Published: February 2008

In this paper we investigate the effect of the Benjamin‐Feir instability on the surface elevation probability distribution. A uniform wave train is unstable to modulational perturbations, giving rise to sidebands in the spectrum of the surface elevation (hence a broadening of the spectrum). Since these sidebands are phase‐locked, one should therefore expect deviations from the Gaussian probability distribution. To calculate the surface elevation probability distribution, we assume that the end state of the instability is given by a stable cnoidal wave solution. The present effect could play a role in nature; especially, it may be relevant for the description of swell.
Relations between characteristic sea wave parameters
Authors: Boccotti Paolo
Published: February 2008

In the stationary Gaussian model of a sea state the ratio between mean zero‐upcrossing wave amplitude and rms free surface displacement is always less than (π/2)1/2, approaching it when the bandwidth tends to zero (narrow band). This is a further argument for a recent explanation given by Longuet‐Higgins of a discrepancy between wave data from the Gulf of Mexico and predictions through the narrow band Gaussian model.
A Monte Carlo approach to the computation of refraction of water waves
Authors: Bouws Evert , Battjes Jurjen A.
Published: February 2008

The equations describing refraction of water waves are based on the geometrical optics approximation, in which wave rays are calculated independently of each other. For this reason the model reacts sensitively to small variations in depth as well as in incident wave frequency and direction. This leads to an uncertainty in the interpretation of the location of individual rays, particularly in cases of large travel distances through regions with weakly irregular bottom topography, as in shelf seas. In this paper, this uncertainty is taken into account from the outset by treating the results of the ray calculations as a case of statistical sampling, in which a tradeoff is made between resolution and confidence. To this end, the area being studied is divided into a number of subregions (bins), in each of which the total wave energy is estimated from the rays passing through it, each ray being considered as a carrier of a certain amount of wave power. The size of the bins determines the spatial resolution. It must be chosen in conjunction with the discretization intervals for ray separation, frequency, and direction, considering also the propagation distance, the length scale of the target area, and the bottom topography. This is illustrated with an example from JONSWAP.
Turbidity in the western basin of Lake Erie
Authors: Paul John F. , Kasprzyk Robert , Lick Wilbert
Published: February 2008

Turbidity data from the Oregon, Ohio municipal water intake in the Western Basin of Lake Erie for the years 1976 through 1979 were examined. A relatively simple formula for the turbidity as a function of bottom shear stress due to wave action and sediment loading from the Maumee River was developed. Excellent agreement was found between the observed and calculated turbidities for all years examined. The results demonstrate that (1) turbidity is directly related to wave action and the resulting bottom stress, (2) sediments from the Maumee River significantly contribute to the amount of entrainable sediment near the Oregon intake, (3) the transport of suspended solids from the Maumee River to the Oregon intake is a significant factor in causing high turbidity, and (4) there is reasonable equality between turbidity in NTU units and suspended sediment concentration in units of milligrams per liter.
Arctic sea ice distribution at end of summer 1973–1976 from satellite microwave data
Authors: Carsey F. D.
Published: February 2008

Passive microwave data at 1.55 cm collected by the Nimbus 5 Electrically Scanning Microwave Radiometer are analyzed to determine the areal extent and distribution of Arctic sea ice at the time of transition from summer melt to fall freeze up of years 1973–1976. While regional variations are great, the total areal coverage of ice‐laden sea changes interannually only about 2% from 7×106 km2. Ice surviving the summer melt has a mean concentration of 0.74 and a volume of 15.8×103 km3, both somewhat lower than earlier estimates. Multiyear ice concentrations were measured by examining on grid cells of 200 km dimension of brightness changes associated with freezing of leads. A significant spatial variation in multiyear ice emissivity was observed which brought about spatial brightness variation comparable to that caused by typical mixtures with open water and first‐year ice. Measurement errors made the detail of interannual changes in emissivity suspect.
An upper ocean moored current and density profiler applied to winter conditions near Bermuda
Authors: Eriksen Charles C. , Dahlen John M. , Shillingford John T.
Published: February 2008

A new moored instrument which makes repeated high vertical resolution profiles of current, temperature, and salinity in the upper ocean over extended periods was used to observe midwinter conditions near Bermuda. The operation and performance of the instrument, called the profiling current meter (PCM), in the surface wave environment of winter storms is reported here. The PCM profiles along the upper portion of a slightly subsurface mooring by adjusting its buoyancy under computer control. This design decouples the instrument from vertical motions of the mooring induced by surface waves, so that its electromagnetic current sensor operates in a favorable mean‐to‐fluctuating flow regime. Current, temperature, and electrical conductivity are (vector) averaged into contiguous preselected bins several meters wide over the possible profile range of 20‐ to 250‐m depth. The PCM is capable of collecting 1000–4000 profiles in a 6‐ to 12‐month period, depending on depth range and ambient currents. A variety of baroclinic motions are evident in the Bermuda observations. Upper ocean manifestations of both Kelvin and superinertial island‐trapped waves dominate longshore currents. Vertical coherences of onshore current and temperature suggest that internal wave vertical wave number energy distribution is independent of frequency but modified by island bathymetry. Kinetic energy in shear integrated over a 115.6‐m‐thick layer in the upper ocean is limited to values less than or equal to the potential energy required to mix the existing stratification. Mixing events occur when kinetic energy associated with shear drives the bulk Richardson number (defined by the ratio of energy integrals over the range profiled) to unity, where it remains while shear and stratification disappear together.
Marine aerosol chemistry at Cape Grim, Tasmania, and Townsville, Queensland
Authors: Andreae Meinrat O.
Published: February 2008

During September 1979, aerosol samples were collected at two coastal sites in the southern hemisphere: Cape Grim, Tasmania, in the southern temperate latitudes, and Townsville, Queensland, in the subtropical region. Cascade impactors and stacked filter units were used for sampling. The samples were analyzed for the light elements (6 ≤ Z ≤ 19) by proton elastic scattering analysis (PESA) and for the heavier elements (Z ≥ 12) by PIXE. As anthropogenic and continental influences are essentially nonexistent along the track of airmasses for several days before they reach Cape Grim, this site is ideally suited for the study of purely marine airmasses. Sulfur at this site is dominated by seasalt, and the submicron sulfur particle mode universally encountered in the southern tropics and the northern hemisphere is almost not detectable here. It can be shown, however, that sulfur in excess of the amount accounted for by seasalt is present in all size fractions. Calcium appears enriched relative to seasalt on all particle sizes. Chlorine shows no net depletion; there may be chlorine enrichment on the intermediate particle sizes combined with losses on the largest and finest particles. Light element analysis of the submicron aerosol showed significant amounts of organic carbon (∼0.3 μg/m3); black soot carbon was not visible in samples from Cape Grim during clean air conditions. Stoichiometric relationships between the light elements suggest that most of the nitrogen and sulfur are present in the form of ammonium sulfate. At Townsville, periods of strong continental influence alternated in the synoptic cycle with marine dominated airmasses. Evidence of biomass burning was present in the form of elevated concentrations of submicron potassium and of soot carbon. Chlorine is not depleted in the large particles. The submicron fraction shows evidence of chlorine loss, which is partially compensated by chloride gain on the smallest particles during the influence of biomass burning. Sulfur has a significant anthropogenic component even under marine conditions. Airmass origin and heavy metal abundance support long‐range transport of sulfur and some heavy metals. At all times a strong submicron mode of sulfur was present at Townsville; stoichiometric calculations suggest that it exists in the form of neutral sulfates.
Sea spray: A further look
Authors: Wu Jin
Published: February 2008

Earlier laboratory and oceanic results on parametric descriptions of concentrations and sizes of spray droplets are critically compared. This summary also encompasses mechanism of spray production, conditions of spray inception, and various distributions of droplets in both laboratory tanks and the field. These results are then used, along with further analyzed calculations of droplet motion in the turbulent surface layer, to relate sea spray to other oceanographic phenomena.
Sources of background current in thr ECC ozonesonde: Implications for total ozone measurements
Authors: Thornton Donald C. , Niazy Nagla
Published: February 2008

The source of the background current in the usual operation of the electrochemical concentration cell ozonesonde is the reduction of tri‐iodide (iodine) normally present in the cathode solution. We can explain the time variations in the background current by the slow rates of solution mass transport and of heterogeneous electron transfer for tri‐iodide. Oxygen does not contribute to the background current through reaction with iodide to produce tri‐iodide. Direct reduction of oxygen at the cathode is negligible once the electrodes have been exposed to iodide for 24 hours. The present background current correction is altitude‐dependent, since it is based on an assumed sensitivity of the electrochemical concentration cell to oxygen. If the background current is independent of altitude and of oxygen, a constant, uncorrected, background current of 0.1 μA would produce an error of +5.5% for the total ozone value of the electrochemical concentration cell for a typical mid‐latitude total ozone value of 0.345 atm cm.
Circulation in the Hudson Shelf Valley: MESA physical oceanographic studies in New York Bight, 1
Authors: Mayer Dennis A. , Han Gregory C. , Hansen Donald V.
Published: February 2008

Over 900 days of current velocity data were obtained at mainly two locations in the inner and outer Hudson Shelf Valley (HSV). The large cross‐axis depth gradients in the HSV, together with the strong winter cyclones and the baroclinic density distribution over the shelf, are primarily responsible for the major circulation features observed in the valley. CSTD data from 12 cruises and meteorological data from JFK International Airport and an environmental buoy were collected concurrently with the current meter data. Although the mean cross‐shelf pressure gradient is generally seaward in the Middle Atlantic Bight, it is shoreward in the HSV below the level of the adjacent continental shelf (shelf horizon), thus imposing a bias toward upvalley flow. The average velocity below the surrounding shelf horizon in the HSV is upvalley or shoreward (west‐northwestward ≈ 290° T) in the range of 2–5 cm/s. The circulation in the HSV is seasonal and individual events can drastically alter the mean picture. The several day average upvalley flow can sometimes approach 20 cm/s when intense winter cyclones pass over the bight and can sometimes also be directed downvalley depending upon the path of the winter cyclone. A topographically controlled barotropic flow commonly opposes the dominant (southeast‐ward) wind direction even near the surface in the winter. In the context of circulation on the open shelf, upvalley (downvalley) flow events generated by winter cyclones are associated with reduced (enhanced) southwestward flow or flow reversals that are northeastward in the lower half of the water column at LTM, a typical mid/shelf site (Mayer et al., 1979). Current meter data suggest that whether or not reversals occur on the open shelf depends upon the interannual variability of the winter wind regime. Upvalley flow events are not confined only to the winter (unstratified) season but are stronger in the winter and can last for several days and longer. During the summer (stratified) season the maximum horizontal KE in the upper part of the water column shifts from the meteorological forcing band, characteristic of winter, to diurnal inertial and semidiurnal frequencies. In the diurnal band there appears to be a strong relationship between the diurnal wind and currents near the surface in the HSV as well as on the open shelf (LTM). The structure of the semidiurnal motions in the inner valley where the depth gradients are larger than in the outer valley has a significant depth dependence unlike most regions on the shelf, i.e., during all times of the year the semidiurnal tidal ellipse is anticlockwise in the lower 20 m of the water column.
Ice nucleus characteristics of Mount St. Helens effluents
Authors: Schnell R. C. , Pueschel R. F. , Wellman D. L.
Published: February 2008

Aerosols were studied in situ and captured on membrane filters from an aircraft flown around Mount St. Helens during its phreatic period in April 1980. Bulk samples of volcanic ash were collected at ground level 120 km downwind on May 19, 1980 and reaerosolized in a laboratory in ash cloud simulation studies. The aerosol and/or ash samples were tested for ice nucleus (IN) activity using four different IN measurement systems (NCAR acoustical counter, bulk drop freezing, NCAR dynamic thermal diffusion chamber, and filter drop freezing). Although threshold IN activity was observed at −8°C in bulk ash, in aerosols there were few IN active at temperatures warmer than −12°C. At −12°C, IN concentrations were less than 0.4 l−1 (400 m−3) even when the aerosol concentrations were as high as 3000 μg m−3. At aerosol concentrations of 500 μg m−3 and less, the IN content of the ash was below background threshold temperatures of −18°C.
On the formation of surface to bottom fronts over steep topography
Authors: Hsueh Y. , Cushman‐Roisin Benoit
Published: February 2008

Imposed horizontal density differences in a laterally unbounded rotating fluid across a bottom of variable depth lead to the formation of surface to bottom fronts with enhanced asymmetry. In a two‐layer fluid, the down‐slope spillage of heavy fluid leads to greater lower layer penetration than the extent of upper layer advance in the opposite direction. These finite amplitude movements generate barotropic flows that have the same direction as the velocity in the layer that thins as a result of the movement. Lower‐layer movements up the depth gradient enhance the generation of lower‐layer flow due to vortex foreshortening and favor a barotropic flow in the same direction. In contrast, lower‐layer movements down the depth gradient enhance the upper‐layer flow for the same reason and favor a barotropic flow in the direction of that flow. Extended down‐slope movement of heavy fluids also leads to the formation of isolated heavy fluid lens over the bottom, within which the flow is reminiscent of observed bottom currents such as that associated with the cold, dense Norwegian Sea water south of the Denmark Strait (Smith, 1976). In addition to bodily displacing the front in the Ekman sense, uniform surface stress directed with deep (shallow) fluid to the right flattens (sharpens) the front. The displacement of the front as a whole also gives rise to additional vortex stretching that leads to further deviation from symmetry in the cross‐front distribution of the barotropic transport.
A preliminary global oceanic cloud climatology from satellite albedo observations
Authors: Hughes N. A. , Henderson‐Sellers A.
Published: February 2008

A pilot study has lead to the establishment of a preliminary predictive relationship for cloud amount as a function of satellite observed system albedo. The United States Air Force 3D‐nephanalysis cloud archive is used as the source of cloud data and is compared with monthly mean system albedo values calculated by NOAA/NESS from the NOAA satellite scanning radiometer data at a resolution of 2.5° by 2.5°. The predictive relationship is applied to ocean areas to produce new global oceanic cloud climatologies.
Use of SEASAT Synthetic Aperture Radar and LANDSAT Multispectral Scanner subsystem data for Alaskan glaciology studies
Authors: Hall Dorothy K. , Ormsby James P.
Published: February 2008

SEASAT synthetic aperture radar (SAR) and LANDSAT multispectral scanner subsystem (MSS) data of three areas in Alaska were studied in order to determine what hydrological information could be extracted using digital data from both sensors. The first area is located in northern Alaska and contains numerous thaw lakes. The other areas contain valley glaciers in the Alaska Range and a piedmont glacier (Malaspina), in south central and southern Alaska, respectively. SAR and MSS subscenes of the thaw lakes and subscenes of the Malaspina Glacier were digitally registered. Registration of the data in the Alaska Range study area was not feasible due to a lack of sufficient tie points resulting from shadowing and layover effects in the SAR data. Results of the data obtained from the thaw lake study area showed that the location and identification of some older remnant lake basins were more easily determined in the registered data using an MSS/SAR overlay than in either SAR or MSS data alone. Separately, both the SAR and the MSS data were useful for determination of surging glaciers based on their distinctive medial moraines, and LANDSAT data were useful for locating the glacier firn zone. In the analysis of the Malaspina Glacier scenes, the SAR data were useful for locating heavily crevassed ice beneath glacial debris, and LANDSAT provided information concerning the extent of the debris overlying the glacier. Together, the data set gave a good representation of the extent of the glacier and crevasse patterns.
M2 ocean tide at Cobb Seamount from SEASAT altimeter data
Authors: Brown R. D.
Published: February 2008

SEASAT altimetry, reduced to sea surface heights and harmonically analyzed at the frequencies of the dominant tidal components, provides a direct measurement of M2 ocean tide parameters near Cobb seamount in the northeast Pacific. Comparison of these altimetric tide parameters with those determined from a bottom pressure gauge located on the summit of Cobb seamount shows fair agreement in amplitude (43 cm versus 81 cm) and good agreement in Greenwich phase angle (243 versus 242 degrees). The precision of the altimeter solution is estimated at 8 cm in amplitude and 10 degrees in phase angle.