bluuebunny/crossref_metadata_2025 huggingface dataset:
UV rocket spectroscopy measurement of the nighttime ozone distribution
Authors: Lean J. L.
Published: February 2008

Nocturnal ozone densities between 32 and 72 km have been derived from observations of the full moon, made by three optical ozone detectors, each comprising three ultraviolet photometers. The three similar detectors were carried on a single spinning rocket, launched at Wallops Island on November 4, 1979. The mean of the three measured ozone profiles is consistent with other nighttime ozone profiles obtained from the LRIR satellite experiment and also from ground based millimeter wave observations. The relative standard error in the mean ozone profile is approximately 5%. At 70 km the ozone concentration of 1.5×109 cm−3 is a factor of three greater than the U.S. Standard Atmosphere, 1976 mid latitude daytime model.
Collinear‐track altimetry in the Gulf of Mexico from SEASAT: Measurements, models, and surface truth
Authors: Thompson J. Dana , Born George H. , Maul George A.
Published: February 2008

From September 17 to October 10, 1978, SEASAT made collinear passes over the Gulf of Mexico. Altimeter data for eight three‐day repeat passes over the eastern Gulf were examined by using an arc segment fitting technique to determine the mesoscale temporal variability of the sea surface. The pattern of sea height variability was then compared with sea height data generated by a numerical model of the Gulf (Hurlhurt and Thompson, 1980) from the simulation of a complete cycle of Loop Current intrusion and shedding of an anticyclonic eddy. The model data was found to match that from the SEASAT altimeter when an anticyclonic eddy separated from the Loop Current and the Loop began to repenetrate into the eastern Gulf. Analysis of sparse ground truth data from ship of opportunity XBTs, satellite infrared imagery of the Loop Current boundary, and synthetic aperture radar (SAR) imagery, also from SEASAT, tend to confirm the circulation patterns deduced from the altimeter data and the numerical model.
SEASAT scatterometer detection of gale force winds near tropical cyclones
Authors: Hawkins Jeffrey D. , Black Peter G.
Published: February 2008

Hurricane center advisories specifying the radius of gale force winds (GFW) in tropical cyclones are severely limited by inadequate data. Their accuracy is especially vulnerable in the data void tropical ocean regions. The SEASAT‐A satellite scatterometer (SASS) sensed surface winds associated with numerous tropical cyclones. Although instrument design ruled out retrieval of winds within the inner core of the storm, surface truth studies indicate SASS can detect the threshold of gale force winds (17–18−1) with an accuracy comparable to the original SEASAT specifications (±2 ms−1 or 10% and ±20°). Accurate and abundant SASS observations were thus used as verification for advisories specifying the radius of gale force winds for tropical cyclones in the Pacific and Atlantic Ocean basins. Advisories were found to consistently overestimate the radius of GFW, often by a factor of two in the Central Pacific. Large asymmetries in the GFW distribution measured by SASS were often in considerable disagreement with symmetric circular and semicircular advisory values. However, advisories that had access to low‐level aircraft data closely matched SASS measured GFW values.
Tropical and mid‐latitude north Pacific sea surface temperature variabililty from the SEASAT SMMR
Authors: Bernstein R. L. , Morris J. H.
Published: February 2008

Sea surface temperature (SST) data from the Scanning Multichannel Microwave Radiometer (SMMR) for the entire SEASAT mission (July 6 to October 10, 1978), was obtained from the SEASAT project office and has been analyzed for the mid‐latitude North Pacific (20°N–50°N, 145°E–130°W), and the eastern tropical Pacific (10°S–20°N, 95°W–145°W). Systematic cross‐scan SST biases were observed in the SMMR data, strongly dependent upon latitude, solar elevation, time of day, and month, The cross‐scan biases are ascribed to incomplete accounting for Faraday rotation of polarized microwave energy propagating upward through the ionosphere. A second systematic SST bias occurred between data of ascending and descending passes nearly 12 hours apart. The bias increased steadily through the mission as the SEASAT orbit moved from 6 A.M./P.M. to 12 A.M./P.M. local sun time coverage. The ascending/descending bias is ascribed to measurements being made at different times in the diurnal cycle of SST. Corrections for the two systematic effects were derived and applied to the SMMR data to produce maps of SST. In mid‐latitude, 10 and 30 day maps of SMMR SST were compared with similar maps produced from routine shipboard SST observations (mostly engine injection temperatures). The monthly SMMR and shipbased maps agreed at the 0.5–0.7°C rms level in July and September, but exhibited a 0.5°C rms scatter about a significant 1.0°C bias in August. The August bias may be a reflection of true midsummer vertical differences in temperature between the 1 cm depth of SMMR observations and the typically 5 m depth of ship observations. Monthly SST anomalies (deviation from climatology) for SMMR and ship exhibited similar patterns, but the SMMR maps appear superior because of their better spatial data coverage. In the eastern tropical Pacific, a sequence of 15 8‐day interval maps were constructed. The maps reproduce known climatological features, in particular the cold tongue of water along the equator. Week‐to‐week variations occur in the intensity of the cold tongue. In addition, wave‐like patterns occur along the meridional gradient just north of the equator, having ∼1000 km wavelength, and propagating west at about 42 km/day.
Sea surface winds from sun glitter observations
Authors: Wald L. , Monget J. M.
Published: February 2008

Solar light reflected by the surface of the sea depends strongly on the sea state which is driven by the wind. The relationship between the reflected light and wind speed is described by the well‐known model of Cox and Munk. Using their model, a method is derived for the retrieval of the synoptic field of wind magnitude from measurements of the glitter pattern from space. This method is applied to data obtained by the TIROS‐N satellite series. Comparison of the wind estimated in this way and the wind derived from isobaric charts shows very close agreement. The method is simple and has application over broad geographical areas.
Some estimates of transport processes in Long Island Sound
Authors: Tolmazin David
Published: February 2008

A parametric description of lateral and vertical oscillatory transport in two segments of Long Island Sound is presented. The vertical eddy viscosity and diffusivity coefficients are estimated on the basis of a model for turbulent kinetic energy transfer. Characteristics of horizontal mixing are examined by means of dimensional analysis. The relative importance of the mechanisms controlling mass distribution in the estuary is evaluated by calculating longitudinal dispersion coefficients in a form introduced by Fisher (1972). It is shown that the mass transport in Long Island Sound is governed mainly by two processes: lateral turbulent dispersion and net longitudinal transport caused by the density gradients.
A vertical section of eddy kinetic energy through the Gulf Stream system
Authors: Richardson Philip L.
Published: February 2008

Ocean current observations made by drifting buoys, SOFAR floats, and current meters are combined to produce the first section of eddy kinetic energy through the Gulf Stream and subtropical gyre along 55°W. Eddy kinetic energy peaks at 2000 cm2 s−2 in the surface Gulf Stream near 39°N and decreases latitudinally and vertically to a low of 0.5 cm2 s−2 in the abyssal gyre interior (4000 m, 28°N). Still further south, eddy energy increases slightly in the region of the North Equatorial Current.
Nimbus 7 SMMR observations of the Bering Sea ice cover during March 1979
Authors: Cavalieri D. J. , Martin S. , Gloersen P.
Published: February 2008

A method of deriving sea ice concentrations from the 0.81‐cm wavelength radiances of the Nimbus 7 scanning multichannel microwave radiometer (SMMR) is described and used in a comparative study of the Bering Sea ice cover during March 1979. Case studies during 2 days in March demonstrate the utility of the SMMR for studying marginal ice zone processes. The first day provides an example of ice divergent conditions with winds from the northeast advecting the ice southwest toward the ice edge. Comparison of the SMMR‐derived ice concentration maps with surface, aircraft, and Tiros‐derived ice charts shows that the microwave data give the ice edge position to within 30 km, corresponding to the highest spatial resolution of SMMR. The, SMMR ice concentrations also give an accurate description of the general morphology of the ice cover including the presence of lee shore polynyas. The second day illustrates the effect of a storm passage on the ice cover. The SMMR ice map for this day correctly describes the retreat of the ice cover and gives the positions of local regions of open water and of high ice concentration within the pack. The two examples show that for the Bering Sea the SMMR algorithm provides accurate large‐scale to mesoscale data on both the ice edge position and the location of low and high ice concentration regions.
Interactions between waves and mean drift in an ice pack
Authors: Mollo‐Christensen Erik
Published: February 2008

In a drifting ice pack, the mean drag depends upon the amplitude of oscillations present, and it reaches a maximum when the amplitude of oscillations along the direction of mean drift equals the drift velocity. The damping of waves entering a pack increases with increasing drift velocity, so waves entering a drifting pack will vary in amplitude because of dissipation. The dispersion of surface gravity waves in an ice pack under compression shows that the group velocity of the waves decreases with increasing mean compressive stress, so there can also be dispersive mechanisms causing wave amplitude variations within the ice pack. The observations in the Norwegian Remote Sensing Experiment, namely that the drag in a drifting pack varied with distance from the pack edge, are in general concord with these results.
Correlative nature of ozone and carbon monoxide in the troposphere: Implications for the tropospheric ozone budget
Authors: Fishman Jack , Seiler Wolfgang
Published: February 2008

The small‐scale vertical variability of tropospheric O3 and CO is examined from a set of simultaneous measurements obtained in July and August 1974, between 55°S and 67°N. From this set of vertical profiles, it is noted that many of the fluctuations are coincident in both species, and a method is presented that quantifies the correlation between the observed O3 and CO variability. A two‐dimensional depiction of the distribution of these O3‐CO correlations shows that there are regions in the troposphere where these trace gases are positively correlated, while at the same time there are preferred locations where these two species are primarily anticorrelated. The regions of anticorrelation are consistent with the traditional picture of the tropospheric ozone cycle, which suggests that this gas is chemically unreactive in the troposphere. On the other hand, the location and magnitude of the region in which these two species are positively correlated suggest that there is considerable in situ production of tropospheric ozone, which is likewise consistent with the more recent interpretation of the tropospheric ozone cycle that shows that this gas is photochemically active in the troposphere. In addition, the existence of a significant in situ source of tropospheric O3 in the northern hemisphere is supported by a modeling study which likewise suggests that the observed hemispheric asymmetry in the distribution of tropospheric O3 is quite likely a result of surface emissions of precursors.
Uranium and plutonium isotopes in the atmosphere
Authors: Sakuragi Y. , Meason J. L. , Kuroda P. K.
Published: February 2008

Uranium 234 and 235 were found to be highly enriched relative to uranium 238 in several rain samples collected at Fayetteville, Arkansas, during the months of April and May 1980. The anomalous uranium appears to have originated from the Soviet satellite Cosmos‐954, which fell over Canada on January 24, 1978. The uranium fallout occurred just about the time Mount St. Helens erupted on May 18, 1980. The concentration of 238U in rain increased markedly after the eruption of Mount St. Helens, and it appeared as if a large quantity of natural uranium was injected into the atmosphere by the volcanic eruption. The pattern of variation of the concentrations of uranium in rain after the eruption of Mount St. Helens was found to be similar to that of plutonium isotopes.
Comparison of the TIROS‐N satellite and aircraft measurements of Gulf Stream surface temperatures
Authors: Legeckis Richard , Bane John M.
Published: February 2008

A comparison is made between multi‐channel infrared (3.7 and 11 μm) temperatures measured by the TIROS‐N satellite and aircraft single channel radiometer and AXBT measurements over the Gulf Stream between Cape Hatteras and Savannah, Georgia, on November 27, 1979. After reducing the noise in the 3.7 μm TIROS‐N data, a multi‐channel method is used to estimate the sea surface temperatures. For a temperature band of 19 to 26°C, the estimated and AXBT measurements are in agreement within a standard error estimate of 0.5°C. A bias of 1.2°C was found between the aircraft radiometer and the AXBT measurements, and part of this bias is attributed to radiometer calibration errors.
Latitudinal variation of tropospheric ozone in a photochemical model
Authors: Hameed Sultan , Stewart Richard W.
Published: February 2008

A zonally, vertically, and annually averaged numerical model of trace gases in the troposphere is used to examine the variation of ozone as a function of latitude. Processes included in the ozone budget are a source due to downward transport of ozone from the stratosphere, deposition at earth's surface, north‐south diffusive transport, and photochemical reactions. Sensitivity of calculated ozone concentrations to the latitude variation and magnitude of the stratospheric source is presented. The model indicates a net photochemical source of ozone in the northern hemisphere and a net chemical sink in the tropical latitudes. Calculated variation of ozone concentration with latitude is in qualitative agreement with observations.
Low‐frequency (ƒ≲1 Hz) stratospheric electrical noise measured by balloon‐borne sensors
Authors: D'Angelo N. , Iversen I. B. , Madsen M. Møhl
Published: February 2008

Low‐Frequency (ƒ≲1 Hz) stratospheric electrical noise is occasionally observed by balloon‐borne sensors. The phenomenon occurs 1–3% of the time, with maximum incidence during the morning hours. It appears to be related to fluctuations of the electrical conductivity of the medium around the balloons, produced by air turbulence due to wind shear and/or gravity waves.
The response of Antarctic icebergs to ocean waves
Authors: Wadhams Peter , Kristensen Monica , Orheim Olav
Published: February 2008

The heave, tilt, and strain responses of three Antarctic tabular icebergs to ocean waves were measured during a 1980–1981 cruise of HMS Endurance to the South Atlantic. The three icebergs, located near the South Sandwich and South Orkney islands, were instrumented with accelerometers, tiltmeters, and wire strainmeters, while a Waverider buoy was used to record the ocean wave field. The thickness of the icebergs was surveyed by a helicopter‐borne radio echo sounder. The heave response occurred mainly at the swell period but with outbreaks of bobbing which lasted for a few cycles at a resonant period (about 40 s), which agreed well with the predictions of a numerical finite element model. The roll response occurred mainly at a long resonant period (40–50 s), which again agreed well with the model, but there was also a significant response at ocean wave periods (5–20 s), which exceeded predictions. The strain response had a component at very long periods, which is unexplained by theory, while the surface strain at ocean wave periods agreed with the simple analytical model of Goodman et al. (1980). Using this model it is possible to predict a wave height and period that will cause breakup of the icebergs, and we conclude that swell‐induced breakup is likely to occur during major storms in the open southern ocean.
Vapor phase and particulate selenium in the marine atmosphere
Authors: Mosher Byard W. , Duce Robert A.
Published: February 2008

Particulate and vapor phase selenium sampling was conducted in urban and coastal Rhode Island, at a coastal site in American Samoa, aboard ship in an upwelling area near the Peru coast, and at two sites in the Hawaiian Islands as part of the SEAREX program. Approximately 25% of the atmospheric selenium was found in the vapor phase at all locations with the exception of Peru, where ∼l0% of the total selenium was in the vapor phase, and above the marine boundary layer in Hawaii, where ∼45% of the selenium was in the vapor phase. Vapor phase selenium appears to be produced naturally as well as anthropogenically. An examination of representative worldwide particulate selenium concentrations reveals the remarkably uniform distribution of atmospheric selenium. Concentrations decrease by only about a factor of 100 from urban to remote marine and continental locations. This may be due to the uniform nature of one important vapor phase source of selenium, the ocean. Vapor to particle conversion of this naturally produced oceanic selenium may explain most of the particulate selenium enrichment observed in remote marine areas.
Fifteen‐day observation of mesospheric and lower thermospheric motions with the aid of the Arecibo UHF radar
Authors: Hirota I. , Maekawa Y. , Fukao S. , Fukuyama K. , Sulzer M. P. , Fellous J. L. , Tsuda T. , Kato S.
Published: February 2008

An attempt was made to have a continuous observation of the zonal wind component in the tropical mesosphere and lower thermosphere for 15 days of August 1–15, 1980, with the aid of the UHF radar at Arecibo (18°N). By using the wind data, together with additional data obtained from meteorological rockets, meteor radar, and Tiros‐N satellite, analyses were made of the time‐mean zonal wind profile, tides, long‐period waves, and short‐period gravity‐type waves, respectively. There appears a remarkable day‐to‐day variation of the zonal wind throughout the region between 70 and 95 km with a characteristic time scale of about 5 days, indicating the passage of traveling planetary‐scale waves in the summertime tropical middle atmosphere. It was also found that the short‐period oscillation with a time scale of a few 10 min appears intermittently in association with the strong vertical shear of the background flow. This oscillation is considered to be the manifestation of the Kelvin‐Helmholtz type instability in the lower thermosphere.
CO2 measurements with an infrared laser spectrometer on flask samples collected at Jungfraujoch high‐altitude research station (3500 meters asl) and with light aircraft up to 8000 meters over Switzerland
Authors: Zumbrunn R. , Friedli H. J. , Neftel A. , Rauber D.
Published: February 2008

We discuss the use of an infrared laser spectrometer for CO2 concentration analysis of flask samples. The precision of the system is 2.5‰, or 0.75 ppm. A series of monthly measurements at the Jungfraujoch high‐altitude research station, Switzerland (3500 m asl), is discussed together with vertical profiles up to 8000 m asl.
Ozone transport by diabatic and planetary wave circulations on a β plane
Authors: Rood Richard B. , Schoeberl Mark R.
Published: February 2008

A β plane model is used to study the transport of ozone and a tracer distributed like ozone. In the first experiment, ozone is transported with a time dependent diabatic circulation in a β channel. Increase in the ozone column density occurs principally through downward advection from the high altitude source region into the lower stratosphere. Compared with observations, the maximum in the total ozone field occurs too late and is too large. Transient planetary waves produce large temporary increases in total ozone near the pole during sudden warming events, but permanent increases are much smaller. Warmings which penetrate below the chemical transition region (major warmings) are most effective in changing the zonal mean ozone distribution. Combining the sudden warming and diabatic circulations simulates many of the observed features of the seasonal changes in total ozone at high latitudes. The diabatic circulation provides the major enhancement of the ozone column density while the transient planetary waves move ozone to high latitudes. This result suggests sudden warmings can play an important role in our understanding of the fluctuations in total ozone, and the final warming may be the key event which determines the date and magnitude of the spring maximum.
Eddy energy of the northwest Atlantic and Gulf of Mexico determined from GEOS 3 altimetry
Authors: Douglas B. C. , Cheney R. E. , Agreen R. W.
Published: February 2008

From May 1975 to October 1978 the GEOS 3 satellite altimeter made numerous repeated observations of sea surface topography in the northwest Atlantic and Gulf of Mexico. By comparing members of about 1000 collinear pairs of altimeter profiles, we have determined mesoscale sea height variability and eddy kinetic energy in these ocean regions. Our results agree qualitatively with estimates made from traditional oceanographic surveys, but significant quantitative differences exist in certain areas, especially in the Gulf Stream between Florida and Cape Hatteras where the altimetric results show less variability. The reason for this appears to be due to differences in spatial sampling. Historical oceanographic measurements are relatively sparse and must be aggregrated into small geographic boxes to compute variability statistics. Results therefore represent a combination of temporal and spatial variability. In contrast, repeated satellite altimeter tracks provide point measurements of changes of sea height and slope. This enables determination of temporal variability alone, a quantity more representative of eddy energy. It is important to make this distinction between space and time because in regions of strong horizontal gradient such as the Gulf Stream, spatial variability can exceed the temporal component. In mid‐ocean where spatial variability is negligible, altimetric and oceanographic results are in excellent agreement.
Properties of multilayered cloud systems from satellite imagery
Authors: Coakley James A.
Published: February 2008

The spatial coherence method for obtaining fractional cloud cover from satellite imagery is extended to the case of multilayered cloud systems. Examples are presented in which simultaneous observations at 3.7 μm and 11 μm are used to solve a system of linear equations for the nonoverlapped fractional cover contributed by each of two layers. The retrieval relies on the assumption that the clouds reside in distinct, well‐defined layers and are optically thick at the wavelengths of observation. Simultaneous observations at 3.7 μm and 11 μm of the separate layers indicate that the assumptions are generally valid. Owing to the reflection of solar radiation at 3.7 μm by low‐level water clouds, the method is limited to nighttime observations.
A new type of overshoot phenomenon in wind wave development and its implication in remote sensing of the ocean
Authors: Huang Norden E. , Parsons Chester L. , Long Steven R. , Bliven Larry F. , Zheng Quanan
Published: February 2008

Laboratory measurements using both wave probes (contact and optical) and radar confirm the existence of a new type of overshoot phenomenon in the wind‐wave development processes. This type of overshoot which occurs at gravity‐capillary wavelengths is practically a function of local wind stress only. It is named the overshoot phenomenon of the third kind. With the existence of this overshoot it becomes obvious that the past assumed simple power law relationship between the rms value of surface slope at a fixed wavelength and the wind stress is untenable. Since such a relationship is one of the key assumptions invoked in the development of algorithms used to date in scatterometry, we have reexamined the published scatterometer data and pointed out the implications of this overshoot phenomenon. Recommendations for improvement of the performance of the scatterometer are also made in light of our new understanding of the wind‐wave development processes.
On the local meteorology at the marginal ice zone of the Bering Sea
Authors: Reynolds Michael
Published: February 2008

In March 1981, detailed meteorological observations were made at the marginal ice zone in the Bering Sea during a period of northerly winds. A 20% increase in wind speed from 90 km inside the edge to 90 km over the ocean was observed. The temperature increased from −11°C to −5°C, and the boundary layer height over the ocean increased from 450 m to 600 m. Data support the concept of a diverging (accelerating) flow. A simple integrated slab model of the atmospheric boundary layer which includes the effects of clouds, surface heat flux, and radiative cooling is applied to the conditions of the marginal ice zone. The model shows that most of the observed variation in the marginal ice zone can be explained by drag variation over the ice and heat flux over the open ocean. Heat flux in the marginal ice zone and cloud processes affect the results only slightly.
The variation of sea surface temperature in 1976 and 1977: 2. The simulation with mixed layer models
Authors: Miyakoda K. , Rosati A.
Published: February 2008

In connection with a study of the extreme weather events over the North American continent in January, 1977, analyses were performed to investigate characteristic properties of spatial and temporal variation of sea surface temperature for the years of 1976 and 1977, using world distribution of sea surface temperature described in the accompanying paper, part 1. The time evolution of ocean temperature patterns for these years are displayed by latitudinal distribution diagrams of sea surface temperature, and longitude‐time (Hovmöller) diagrams. Gill‐Turner's integral model and Mellor‐Durbin's turbulence closure model of the mixed layer were applied to calculate the sea surface temperature anomaly in the northern hemisphere, using realisitic atmospheric forcing. Increase of time variability of the external forcing leads to an appreciably improved simulation of the sea surface temperature anomaly fields. Both models gave reasonable predictions for about 5 months in winter time, if the realistic external forcings were specified.
Formation of thermoclines in zero‐mean‐shear turbulence
Authors: Thompson Rory O. R. Y.
Published: February 2008

Heating q at the surface of a turbulent and initially unstratified ocean may form a thermocline if strong enough. It is proposed here that the heating is strong enough if turbulence occurs infrequently enough past some depth not to transport heat downward. Turbulence is taken not to occur if the gradient Richardson number Ri = N2/(uz2 + Vz2) rises above a critical value of 0.25. The probability that this occurs becomes very small when and where the population Richardson number
is greater than about 1.33. This traps the heat above that layer, increasing
and forming a thermocline. Let stirring action K be generated at a depth D below heating, and scale the heating as B = gαq/ρcp. Then the population Richardson number criterion translates: if H = BD4/K3 < Hc ≈ 1.6, a thermocline will form above the stirring (“tidal friction”). If H < Hc, no thermocline will form above the stirring, but after a time 0.9(K/B)1/2, the thermocline will form at a depth 0.6D+2.2(K3/B)1/4 below the stirring (“wave breaking”). These theoretical results match experimental results of Hopfinger and Linden (1982).
The response of the coastal boundary layer to wind and waves: Analysis of an experiment in Lake Erie
Authors: Schwab David J. , Meadows Guy A. , Bennett John R. , Scnultz Howard , Liu Paul C. , Campbell Joan E. , Dannelongue Herve H.
Published: February 2008

Wind, waves, currents, and water levels were measured near Lake Erie's southeastern shore during fall 1981. Data were recorded continuously at a wave research tower 6 km offshore at three Waverider buoys deployed around the tower and at three current meter moorings along a transect between the tower and the shore. During four storm episodes, wave and current data were also recorded from a dense array of instruments along a transect across the surf zone. A statistical analysis of the deep water data was performed, and histograms of meteorological parameters, wave parameters, and water level slope were plotted as a function of wind direction. The atmospheric boundary layer was usually unstable; on the average, the water was 2–3°C warmer than the air. This was true for all wind directions. At the tower the highest waves were associated with the greatest fetch distances to the WSW and WNW directions. The longest period waves were also associated with these wind directions. The mean water level slope was opposite the mean wind direction. This discrepancy is most likely due to small leveling errors in the water level gages. The variation of currents with wind direction was also examined. The currents are strongest when the winds are from the west, the quadrant with the strongest wind speeds. However, there are strong currents (5–10 cm/s) for all wind directions. The deep water currents are basically shore parallel, with the onshore/offshore component averaging 39% of the root mean square longshore component. Analysis of the four storm episodes reveals the influence of the offshore currents on the flow regime within the surf zone. Quantitative estimates of the longshore momentum balance outside the surf zone show wind stress and pressure gradient to be the dominant dynamic terms. Inside the surf zone, the radiation stress, wind stress, and bottom stress terms all have comparable effects and are usually larger than the acceleration and pressure gradient terms. In between, there is evidence of longshore flow reversals in the breaker zone and the effect of seiche‐induced offshore currents on the near‐shore flow regime.
Estimates of the relative roles of diapycnal, isopycnal and double‐diffusive mixing in Antarctic Bottom Water in the North Atlantic
Authors: McDougall Trevor J. , Whitehead J. A.
Published: February 2008

Whitehead and Worthington (1982) have measured the fluxes of heat and salt due to the northward flow of Antarctic Bottom Water through a passageway 300 km wide between the Ceara Rise and the Mid‐Atlantic Ridge at about 4°N. Downstream of this “sill” the temperature and salinity of the underflowing water increase, and Whitehead and Worthington have described this change as being due to “downward” fluxes of heat and salt across isothermal surfaces. We consider the relative roles of three separate mixing processes to these “downward” fluxes of heat and salt across isotherms, and we use this information to decide between Whitehead and Worthington's two separate estimates of the volume transport of Antarctic Bottom Water: one based on current meter data, and the other based on geostrophic calculations. The slope of the θ‐S locus of bottom water as it moves northward past the equator provides a valuable extra constraint on the relative importance of the three mixing processes. We conclude that the dominant mixing process is diapycnal (i.e., cross‐isopycnal) turbulent eddy diffusion and that the geostrophic data set of Whitehead and Worthington is consistent with the mixing ideas presented here, whereas their current meter data set is not.
On the electromagnetic fields induced by oceanic internal waves
Authors: Chave Alan D.
Published: February 2008

Model spectra for the electric and magnetic fields induced by oceanic internal waves are obtained by combining Green function solutions to the two electromagnetic modal equations with the Garrett‐Munk kinematic description of the internal wave field. The poloidal magnetic mode is dominant at frequencies above 3f, where f is the local Coriolis frequency, and self and mutual induction are not important over this range. The toroidal magnetic mode is increasingly important at frequencies below 3f and is sensitive to the conductivity structure below the seafloor for nearinertial frequencies. The moored electric field is shown to be largely a measure of the local velocity field at high frequencies. The vertical electric field is sensitive to the horizontal velocity field, while the horizontal electric field primarily reflects the vertical velocity field and is quite small at the seaearth and sea‐air interfaces. The magnetic field is a measure of the spatially averaged velocity field and is dominated by the poloidal magnetic mode. Electromagnetic boundary effects reduce the horizontal magnetic spectrum by decades at the seafloor and sea surface. At the seafloor and sea surface, internal wave‐induced magnetic fields are within an order of magnitude of their externally induced counterparts, while in the ocean's interior, internal waves are probably the largest source of magnetic signals in the period range one day to one hour. The internal wave‐induced electric field is not measurable except in the vertical component.
Spatial variation of sea surface temperature and flux‐related parameters measured from aircraft in the JASIN Experiment
Authors: Liu W. Timothy , Katsaros Kristina B.
Published: February 2008

Spatial variation of some parameters measured on two aircraft flying 100‐km box and 200‐km triangular patterns at low levels in the atmospheric boundary layer during the Joint Air Sea Interaction Experiment in the North Atlantic was studied. The variation should be representative of summer conditions in mid‐latitude oceans. The variance density of remotely sensed sea surface temperature, corrected for sky reflection, is found to depend on the one‐dimensional wave number raised to the power of approximately −5/3. Nonuniform clouds add low‐frequency variance to observations of a downward looking radiometer and result in steeper slope of the spectra of uncorrected sea surface temperature. Turbulent fluxes of momentum, sensible heat, and moisture were determined with the bulk formulae from the parameters (wind speed, temperature, specific humidity, and sea surface temperature) measured from the aircraft. The averages of these fluxes over each flight leg were compared with the fluxes determined from the parameters averaged over the same leg. The difference is negligible, showing that spatially averaged observations, such as those from spaceborne sensors, can be used in the bulk formulae to evaluate the fluxes.
Drifter observations of coastal surface currents during CODE: The method and descriptive view
Authors: Davis Russ E.
Published: February 2008

Observations of near‐surface coastal currents were made off the Northern California coast during the Coastal Dynamics Experiment (CODE) by using 164 current‐following drifters. Viewed as flow visualization descriptions, the results disclose a number of energetic mesoscale features that dominate across‐shelf transport. Examples of eddies, jets, convergences and across‐shelf “squirts” are shown and related to moored current observations, wind forcing, and mesoscale features observed in satellite surface temperature imagery. Convergences appear to be most common when currents reverse following relaxation of normally upwelling‐favorable winds. Squirts are apparently the cause of cold water plumes extending away from the coast; they appear most frequently at coastal promontories.
Waves and longshore currents: Comparison of a numerical model with field data
Authors: Wu Chung‐Shang , Thornton Edward B. , Guza R. T.
Published: February 2008

A two‐dimensional numerical model is used to predict the shoaling and breaking of surface gravity waves, and the resulting longshore currents, for 5 days of the Nearshore Sediment Transport Study Santa Barbara experiment. Data with incident waves having narrow‐banded frequency and directional spectra are selected for comparison in accord with the model assumptions of unidirectional and monochromatic waves. The rms wave height is used for expressing wave energy in the calculations. The current model includes bottom friction, lateral mixing, and nonliner convective accelerations. The extensive field measurements of waves, including quantitative directional information, and longshore current distributions are used to test the model results. The predicted rms wave heights are consistent with the measurements. By tuning the model with field data of longshore currents, the comparison between the model and data shows good agreement, and the obtained values of free parameters are relatively constant for the five experiment days.
The utility of multiple tracer distributions in calibrating models for uptake of anthropogenic CO2 by the ocean thermocline
Authors: Peng Tsung‐Hung , Broecker Wallace S.
Published: February 2008

Two‐dimensional thermocline ventilation models for the temperate North Atlantic with differing circulation patterns were calibrated to yield a tritium distribution similar to that observed during the GEOSECS survey. These models were then run for 3He, bomb‐produced 14C, radiokrypton, and freons. They were also run for the uptake of fossil fuel CO2. While the models differ significantly in their ability to match the observed 3He and 14C distributions, these differences are not large enough to clearly single out one model as superior. This insensitivity of tracer‐to‐tracer ratio to model design is reflected by the near identity of the fossil fuel CO2 uptake by the various models. This result suggests that the uptake of CO2 by the sea is limited more by the rates of physical mixing within the sea than by gas exchange across the sea surface. If so, then the hope that models employing outcropping isopycnals will enhance the CO2 uptake by the sea and thereby lead to a narrowing in the gap that exists for anthropogenic CO2 budgets is not well founded. The interim strategy of using reservoir models calibrated by tracer distributions appears to be sound.
Small‐scale cyclones on the periphery of a Gulf Stream warm‐core ring
Authors: Kennelly Maureen A. , Evans Robert H. , Joyce Terrence M.
Published: February 2008

Small‐scale cyclones found around Gulf Stream warm‐core ring 82B are investigated by using infrared satellite images and current information obtained with an acoustic‐Doppler velocimeter. Currents in these cyclones reveal speeds ranging from 20 to 80 cm/s. One small cyclone or “ringlet” found in June 1982 was studied extensively by removing the basic rotational velocities of 82B. The azimuthal velocity field for this ringlet was used with the gradient current equation to calculate the absolute dynamic topography at 100 dbar. It was found that the ringlet was 13 dyn‐cm lower than its surroundings. In addition, neglect of the centrifugal term would have changed the dynamic topography of the ringlet by 30%. From a comparison with CTD data the absolute reference level was determined, and a vertical profile of horizontal currents was calculated for the ringlet. Other cyclones were found throughout the slope water region around warm‐core ring 82B with observable lifetimes of 1 to 2 weeks. The northeast quadrant of 82B was a favored generation site for ringlets. Two cyclones were observed to form in this region and were advected anticyclonically around 82B. Typically, at any one time, six cyclones with diameters of approximately 40 to 50 km can be detected north of the Gulf Stream by using satellite images.
A wind‐induced mesoscale eddy over the Vancouver Island continental slope
Authors: Thomson Richard E. , Gower James F. R.
Published: February 2008

We use Nimbus 7 coastal zone color scanner imagery and direct oceanic measurements to investigate an extensive mesoscale circulation pattern that developed off the coast of Vancouver Island, British Columbia, in July 1979. Particular emphasis is on a well‐defined cyclonic eddy that formed in 1000 m of water over the central portion of the continental slope. Characteristic features of the eddy included a core diameter of 25 km, a vertical scale of 500 m, azimuthal current speeds of 0.20±0.05 m s−1, and an alongshore propagation speed of 1.7±0.6(×10−2) m s−1. According to our interpretation, the eddy, and the attendant mesoscale circulation pattern, evolved through mixed barotropic‐baroclinic instability of a poleward flowing coastal “jet” that had been generated during a 1‐week period of strong 0(10 m s−1) southeast winds. Formation of the eddy appears to have taken place 5–7 days after onset of the jet and may have been triggered through perturbation of the mean flow by a 0(10‐km) “bump” in the continental slope. Results imply that eddylike circulation observed off the coast of Vancouver Island is frequently initiated by “local” alongshore winds rather than through instability of the prevailing California Current regime, as previously suggested in the literature. The results also indicate that thermal imagery often fails to delineate major oceanic surface features off the coast.
Flow of electrical current from world ocean to atmosphere
Authors: Blanchard Duncan C.
Published: February 2008

The positively charged drops from bubbles bursting at the surface of the sea produce a flow of current from the world ocean to the atmosphere. The charge flux has been measured to be about 4×10−11 C m−2 s−1. Multiplying this by the latest estimates of the area covered by whitecaps on the world ocean between 70°N and 70°S latitude gives a maximum current of 130 A.
Instabilities in a rotating fluid with constant shear
Authors: Criminale W. O.
Published: February 2008

Using an instability problem as the basis, Gammelsrød (1975) developed a rationale for Langmuir circulation. By means of a solution that is valid even for the nonlinear system, the proposed problem is reexamined from a more general point of view, including conditions or restrictions on the mean flow variables and scales, and it is found that, although the instability is possible, it is not particularly applicable to the situation envisioned. Salient other possibilities with respect to the stability for this important model are also discussed.
Wave refraction in an ocean front
Authors: McLeish William , Ross Duncan B.
Published: February 2008

Side‐looking airborne radar near Cape Hatteras, North Carolina, recorded images of ocean waves, wind streaks, and intermediate water bodies within the Gulf Stream front. In the enclosed Waters of Pamlico Sound the radar images showed good accuracy in defining directions and distinguished waves from wind streaks at overlapping frequencies in the spectrum. In passing through the cyclonic Shear in the Gulf Stream front, waves from both sides turned to their left and so specified their directions of propagation. Differences between spectra obtained across the front are in accord with current refraction theory. An inverse wave refraction calculation furnished current shear values from which horizontal profiles of water velocity were compiled. The total calculated velocity change of 1.5 m/s is similar to previous measurements. A secondary front near shore contained a velocity difference of 0.25 m/s. Velocity changes across the Gulf Stream front were correlated with temperature changes. The radar there showed bands of high reflectivity at the edges of intermediate water bodies, whose temperature differences implied very small velocity steps. Increased roughness at the intermediate water boundaries was attributed to current interaction with waves.
Theory of acoustic measurement of internal wave strength as a function of depth, horizontal position, and time
Authors: Flatté Stanley M. , Stoughton Roland B.
Published: February 2008

High‐frequency (≳ 1 cpd) variations in travel time of acoustic transmissions over ocean mesoscale distances are known to be dominated by the effects of internal wave displacements of the sound speed stratification (Flatté et al., 1979; Flatté, 1983a). Variations in the difference in travel time between transmissions in opposite directions along the same path (reciprocal transmissions) are dominated by internal wave currents [Munk et al., 1981]. We investigate the usefulness of a two‐mooring acoustic system for determining the statistical variances of internal wave displacements and currents as a function of depth, geographical position, and time. We find that Statistical fluctuations in the internal wave field itself prevent recovery of range‐dependent information between the two moorings. However, range‐averaged information can be obtained about mean energy level and about vertical energy migration. We find that uncertainties in the buoyancy and sound speed profiles do not significantly affect the usefulness of the method.
A numerical study of the effects of anomalous North Atlantic atmospheric conditions on the infrared measurement of sea surface temperature from space
Authors: Minnett P. J.
Published: February 2008

A line‐by‐line radiation transfer model is used to simulate the brightness temperatures measured in the atmospheric “window” between 10 and 13 μm by the advanced very high resolution radiometer (AVHRR/2) on the NOAA 7 satellite. The atmospheric properties are described by a large set of marine radiosonde profiles over the NE Atlantic Ocean and characterize the month of July. The effects of anomalous atmospheric conditions on the brightness temperatures are simulated by independently adjusting the humidity and temperature profiles, and it is found that the consequences of humidity anomalies are greater if they occur at height (pressure of <850 mbar), whereas temperature anomalies have greater effect if they are in the lower troposphere. Sea surface temperature (SST) retrieval coefficients, optimized for these July conditions, are derived and tested against simulated brightness temperatures derived using a “withheld” set of profiles and found to be accurate. Mean errors of several tenths of a kelvin were found when other, nonoptimized coefficients, taken from the literature, were applied to the original July conditions. The mean errors in SST derived using the optimized coefficients can also be a few tenths of a kelvin in extremely anomalous atmospheric conditions. These errors are large enough to be of concern to climate researchers but probably too small to permit direct verification by comparison with currently available conventional SST measurements.
Mesoscale ocean eddy measurements by multibeam altimetry
Authors: Lee Hyo Sang , Parsons C. L.
Published: February 2008

A multibeam microwave radar altimeter concept is numerically simulated to evaluate its capability to remotely sense mesoscale oceanographic features and eddies in particular. The study tests the sensitivity of the sensor to variations of systematic and environmental parameters, including sensor attitude angle, sensor position, and system errors. A novel concept of computing eddy vorticity from the multibeam data is explored. Application of this concept to the detection of simulated ocean eddies in the presence of tracker noise gives excellent results; the technique is shown to be simple and accurate. The minimum size of the eddy detectable by the multibeam altimeter is presented for a given performance characteristic of the radar.
An important scientific controversy: Oceanic CO2 fluxes
Authors: O'Brien James J.
Published: February 2008

The following three papers [Broecker et al., this issue; Smith and Jones, this issue; Wesely, this issue] are a detailed discussion between the oceanographic geochemical community and the physical oceanographic air‐sea interaction community. It is my opinion that these papers provide for the general scientific community an in‐depth review of the methods to estimate CO2 fluxes across the sea surface.

The differences between the two scientific groups were brought to my attention when we received the original manuscript submitted by and finally published by Smith and Jones [1985]. During the review process, all geochemists criticized the manuscript and all physicists applauded it. W. Broecker was invited to provide a response to Smith and Jones [1985] and they and Wesely et al. [1982] were invited to provide replies to Broecker et al. [this issue].