bluuebunny/crossref_metadata_2025 huggingface dataset:
transient Workman‐Reynolds freezing potentials
Authors: Caranti J. M. , Illingworth A. J.
Published: February 2008

There are two processes by which Workman‐Reynolds freezing potentials may result in thunderstorm electrification or aircraft precipitation static. One possibility is that charge is transferred when supercooled drops splash on the hailstone or aircraft surface. Alternatively, freezing potentials may develop when cloud droplets freeze on these surfaces and persist long enough to affect charge transfer when ice crystals subsequently collide with the ice‐covered surface. Laboratory experiments on the development of these freezing potentials when bulk supercooled solutions freeze, and when raindrops and cloud droplets freeze on impact with an ice surface, show that (1) any potentials developed are very much smaller than the published values for the quasi‐static case; (2) in situations of atmospheric importance the drops will be supercooled, and such solutions are very much less efficient in developing potentials than non‐supercooled ones; (3) cloud droplets freeze very rapidly, and if any freezing potential develops during this time, then it decays in less than 5 ms and is statistically unlikely to affect charge transfer in subsequent collisions with ice crystals. We conclude that in the atmosphere Workman‐Reynolds potentials do not influence the charge transferred by colliding precipitation particles and briefly consider other relevant mechanisms.
Heat fluxes over the eastern tropical Pacific and aspects of the 1972 El Niño
Authors: Reed R. K.
Published: February 2008

Recently evaluated flux formulas were used with an edited ship‐of‐opportunity data set for the 1970's decade to derive estimates of the individual surface heat fluxes and the total or net surface energy exchange for the eastern tropical Pacific. Absorbed solar radiation is the dominant heat flux in the region, and latent heat exchange is the second most important component; total cloud cover and wind speed are generally the most significant atmospheric variables. Over much of the area, the annual excess of net surface flux appears to be balanced by heat advection in the South Equatorial Current. Although the seasonal cycles of sea surface temperature seem to be produced by variations in net surface flux over parts of the area, they do not appear to balance off Peru and near the equator. Instead, water temperature seems to be noticeably affected by the seasonal cycle of upwelling and advection along the Peru coast. This data set was also used to derive sea surface temperature and net surface heat flux departures from the mean for individual months during the 1972 El Niño. The magnitude and speed of the initial warming along the eastern ocean margin indicate changes in heat content at least an order of magnitude greater than any departures of net surface flux; this fact and the subsequent poleward and westward spreading of warm water support an advective origin, especially Wyrtki's hypothesis of an eastward propagating Kelvin wave. Subsequent changes during an El Niño episode also do not seem to be influenced appreciably by variations in surface heat exchange.
Seasonal, latitudinal, and secular variations in the abundance and isotopic ratios of atmospheric carbon dioxide: 1. Results from land stations
Authors: Mook Willem G. , Koopmans Marjan , Carter Alane F. , Keeling Charles D.
Published: February 2008

Between March 1977 and February 1982, 517 samples of air were collected in 51 glass flasks at four stations in the northern hemisphere near the Pacific ocean and at the South Pole. First, the CO2concentration of each sample was determined by nondispersive infrared gas analysis, and then the 13C/12C and 18O/16O ratios of the cryogenic extracted CO2 were determined with a triple collector mass spectrometer. For each station the secular trend and seasonal variation in 13C/12C ratio have been established as a function of CO2 concentration. The seasonally adjusted 13C/12C ratio is found to have decreased at a rate of about 0.02‰ per ppm increase in the seasonally adjusted CO2 concentration and to vary with latitude as expected if CO2 is being released by fossil fuel combustion in the northern hemisphere and from ocean water near the equator. At the three northernmost stations (La Jolla, California, at 33°N and two Hawaiian stations near 19°N) the 13C/12C ratio of the CO2 added to and withdrawn from the atmosphere during one annual cycle is circa −29‰ with respect to standard PDB, as expected from the exchange of atmospheric CO2 with the carbon of terrestrial plants. Near the equator at Fanning Island (4°N) the similarly computed 13C/12C ratio is −21‰, while at the South Pole it is about −13‰. This suggests that the seasonal variation in the southern hemisphere and tropics is partially a result of oceanic CO2 exchange.
Characterization of aerosols in marine environments (Mediterranean, Red Sea, and Indian Ocean)
Authors: Prodi F. , Santachiara G. , Oliosi F.
Published: February 2008

A study of the aerosol in different marine environments was performed during a scientific cruise on the vessel Salermum from the Mediterranean Sea to the Indian Ocean (January 1 to February 27, 1979). The aerosol particles were sampled on membrane filters and in a single‐stage impactor. The particles on the filters were analyzed for soluble Mg, Ca, K, Na; for mineral aerosol mass concentration; and for chloride particles. An elemental analysis, using the microprobe attached to the scanning electron microscope (SEM), was carried out. The aerosol particle size distribution was determined from the photographs of the filter surface taken by the SEM. The concentration of the ice‐forming nuclei was measured by developing the filters in a static diffusion chamber. Chloride particles were also independently detected on the single‐stage impactor slides. The data, also discussed in association with the atmospheric turbidity measurements taken during the same cruise, give a clear picture of the aerosol characteristics, which reflect in a detailed and sensitive way the origin of the air mass in which they were sampled.
On the motion of suspended sand particles
Authors: Nielsen Peter
Published: February 2008

The motion of suspended sand particles is studied by means of a new perturbation solution to the equation of motion. In the first approximation, fluid accelerations are neglected so that the relative velocity between sand and water is everywhere equal to the still water settling velocity
. It turns out that some of the most important mechanisms of sediment suspension, such as trapping in vortices, can be derived from this “zero order solution” when the flow structure is given proper consideration. The next level of solutions takes into account the effect of fluid accelerations by including terms of order of magnitude
. As a main result it is shown that pure wave motion does not cause a net reduction of settling velocity of this order of magnitude. Finally the effect of drag nonlinearity is studied for the case of an oscillatory flow. It is shown that this effect is of the order of magnitude ε2 and without practical importance for sediment suspension by waves.
Spectra of humidity, temperature, and wind over the sea at Sable Island, Nova Scotia
Authors: Smith Stuart D. , Anderson Robert J.
Published: February 2008

Spectra and cospectra of humidity, temperature, and wind fluctuations from a series of experiments at Sable Island, Nova Scotia, are sorted into three classes of stability, normalized according to Monin‐Obukhov similarity theory, and compared with other published spectra from both land and water surfaces. The conditions for local isotropy are met at normalized frequencies ƒn≥1 in neutral and unstable conditions and at ƒn≥2 in stable conditions. The downwind spectrum over water in neutral and unstable conditions is lower than over land, while in stable conditions there is no difference. The stable humidity spectrum is found to resemble the temperature spectrum. The stability dependence of humidity and thermal turbulence levels and structure functions is scaled by similarity theory. Dissipation estimates of humidity and temperature fluxes compare well with direct eddy flux measurements, while momentum fluxes are underestimated.
Models of depth‐dependent bioturbation at MANOP Site H in the eastern equatorial Pacific
Authors: Kadko David , Heath G. Ross
Published: February 2008

The vertical distribution of excess 226Ra sorbed to manganese‐rich sediments from a box core taken at MANOP site H (6°34′N, 92°48′W) in the eastern equatorial Pacific can be modeled only if the rate of bioturbation decreases rapidly downward from the seafloor within the upper few centimeters of sediment. Independent bioturbation rates estimated by balancing dissolved and particulate diagenetic Mn fluxes are compatible with the values obtained from the radium model. Such results are consistent with 210Pb and 230Th measurements reported here and with MANOP lander and porewater observations that rapid organic carbon degradation in these sediments consumes oxygen within a few centimeters of the sediment‐seawater interface. The modeled decrease in bioturbation (expressed as a biodiffusion coefficient) is consistent with values of more than 25 cm2/kyr at the surface falling to less than 0.4 cm2/kyr at a depth of 14 cm.
Sea surface temperatures of the coastal zones of France observed by the HCMM satellite
Authors: Deschamps P. Y. , Frouin R. , Crépon M.
Published: February 2008

The Heat Capacity Mapping Mission experimental satellite was launched in April 1978 and provided data until July 1980. Although the basic mission objective was the measurement of diurnal temperature variations of the earth's surface for soil and geology applications, the characteristics of the heat capacity mapping radiometer onboard the satellite (temperature sensitivity of 0.3°C, instantaneous field of view of 0.5 km) also recommended it for use in oceanographic studies. The data acquired during the period from May 1978 to May 1979 were systematically utilized for evaluation of sea surface temperature in French oceanic regions (North Sea, English Channel, Celtic Sea, Bay of Biscay, and western Mediterranean Sea) and for study of sea surface temperature‐related dynamic phenomena. Comparisons were made of the radiometric performance of the heat capacity mapping radiometer to that of the very high resolution radiometer and the advanced very high resolution radiometer onboard meteorological satellites. They demonstrate the decisive gain in quality of the heat capacity mapping radiometer over the very high resolution radiometer and the similarly improved quality of the heat capacity mapping radiometer and advanced very high resolution radiometer for the observation of mesoscale sea surface temperature features. The utilization of available photographic products proved very suitable, since they had been geometrically corrected and enhanced in the sea surface temperature range, consequently avoiding many of those cases requiring involved computer treatment. On the basis of the interpretation of photographic products, conclusions have been drawn regarding several oceanic phenomena: (1) The thermal effluent of the Rhine‐Meuse system is affected by the residual tidal current of the North Sea. The extent of the offshore diffusion of the effluent is influenced by winds from the northeast and west which, respectively, retard or accelerate the residual current; (2) images exhibiting cold water along the edge of the continental shelf strongly support the hypothesis of a mixing process due to internal waves generated by the action of tidal currents at the edge of the shelf; (3) large‐scale eddy structures detected during the summer in the region of the Mediterranean Sea around 6°E and 38°N may be linked to a phenomenon of barotropic‐baroclinic instability; (4) significant diurnal heating of the surface layer (several degrees Celsius) observed in the Mediterranean Sea is related to the presence of weak winds, leading one to interpret with caution the daytime sea surface temperature satellite observations made during the summer period.
The effect of particle size on the light attenuation coefficient of natural suspensions
Authors: Baker Edward T. , Lavelle J. William
Published: February 2008

Laboratory calibration of a beam transmissometer by using natural sedimentary particles fractionated into seven size classes demonstrates that slopes of light attenuation vs. particle mass concentration regressions systematically vary with the size distributions of the particles. Suspensions with a mean particle size of 8.5 μm attenuate 660‐nm light 15 times more efficiently than suspensions of similar particles with a mean diameter of 48 μm. Theoretical calculations of attenuation, based on scattering by spherical particles with the measured size distributions, underestimate observed attenuation by factors of 2–4, apparently because the nonspherical shape and roughness typical of natural particles create an effective optical diameter larger than that for a sphere of equal volume. These laboratory results agree with the trend established from a survey of published field data showing that calibration slopes experience a steady increase from inshore high‐energy waters, where large particles are common, to offshore low‐energy waters, where large particles are rare.
The stratification and water masses at Drake Passage
Authors: Sievers Hellmuth A. , Nowlin Worth D.
Published: February 2008

The waters at Drake Passage are known to be separated horizontally into four distinct zones of relatively small geostrophic shear by three fronts in which the shear and eastward flow are large. The two northern fronts, Subantarctic Front and Polar Front, that bound the Polar Frontal Zone comprise most of the transport of the Antarctic Circumpolar Current. Vertical sections of closely spaced (∼50 km) oceanographic stations made across Drake Passage in the summers of 1975 and 1976 produced quality measurements of temperature, salinity, oxygen, silicate, nitrate, and phosphate. Based on these data, a traditional description of characteristic distributions is presented. Good sampling resolution in the vertical allows maxima in hydrostatic stability to be traced laterally (approximately along isopycnals) between individual stations. Eleven strata of maximum stability are identified. Most vertically separate distinct water masses. The most pronounced stability stratum is associated with the seasonal pycnocline; north of the Polar Front, it separates the Subantarctic Surface Waters from Subantarctic Mode Water. To the south of the Polar Front the seasonal pycnocline is found slightly above the temperature minimum characteristic of the Antarctic Surface Waters in austral summer. This stability stratum extends northward near the base of the Subantarctic Mode Water. Another stability stratum extending across the entire passage forms the upper boundary for the Circumpolar Deep Water. South of the Polar Front, this stratum is at the base of the Antarctic Surface Water; to the north it is the lower boundary of the Antarctic Intermediate Water. Although Subantarctic Mode Water and Antarctic Intermediate Water are separated by a stability stratum north of the Polar Front, there is no such separation between Antarctic Intermediate Water and the temperature minimum of the Antarctic Surface Water south of the front. This suggests that Subantarctic Mode Water and Antarctic Intermediate Water are distinct and that the latter derives from the surface waters south of the Polar Front. At greater depths a horizontally discontinuous stratum is found between the Upper and Lower Circumpolar Deep Water. Two horizontally continuous stability strata are found near the base of the Circumpolar Deep Water, marking the transition to a high‐silicate variety of denser deep water from the Southeast Pacific Basin. The densest water mass found is Weddell Sea Deep Water, which flows through a gap in the South Scotia Ridge and along the southern Scotia Sea to fill the trough in the southern Drake Passage. It is overlain by a laterally continuous stratum of relative maximum stability.
The distribution of measured and simulated wave heights as a function of spectral shape
Authors: Forristall George Z.
Published: February 2008

First‐order theory predicts that zero‐crossing wave heights should have a Rayleigh distribution, but measured waves are slightly smaller than the theoretical prediction. Suggested explanations for this discrepancy have included the nonlinearity of the wave surface, limitations on height as a result of breaking, and the effect of spectral width. In a recent paper, Tayfun (1981 b) showed that the shape of the spectrum influences the height distribution because the wave envelope has different amplitudes at the time of the crest and trough. We have compared the distribution developed by Tayfun to simulated waves with different spectral shapes as well as to observations and found excellent agreement. The theoretical, simulated, and measured wave height distributions agree to within 1% in height. This result reinforces the conclusion that linear Gaussian simulations can reproduce many features of ocean waves.
The dependence of X band microwave sea return on atmospheric stability and sea state
Authors: Keller William C. , Plant William J. , Weissman David E.
Published: February 2008

The dependence of microwave sea retun at an incidence angle in the Bragg regime on wind speed, atmospheric stability, dominant wave slope, and dominant wave frequency has been measured. The measurements were made from a tower in the Gulf of Mexico with a CW, X band microwave system operating at a 45° incidence angle. Measured microwave parameters were relative cross sections and ocean wave‐radar modulation transfer functions obtained with antennas directed into wind and waves. The data reveal that cross sections increase with decreasing z/L (z being height and L being the Obukhov length) in unstable atmospheric conditions. The rate of increase is much higher than that of surface stress calculated on the basis of present boundary layer models. Furthermore, these data indicate that in near‐neutrally stratified atmospheric conditions, X band cross sections at constant and relatively low wind speeds increase with long‐wave slope, while modulation transfer functions decrease with long‐wave slope. No clear dependence of either parameter on wave slope was observed in highly unstable conditions. The implications of these findings for other microwave frequencies and for scatterometry and microwave imagery of the sea are briefly discussed.
Removal of ambiguity of two‐dimensional power spectra obtained by processing ship radar images of ocean waves
Authors: Atanassov V. , Rosenthal W. , Ziemer F.
Published: February 2008

The usual spatial power spectra of ocean wave images taken from PPI of a ship radar show an ambiguity in the wave propagation direction. A simple numerical procedure is suggested and realized to remove this ambiguity. It makes use of the data from two consecutive turns of the radar antenna as well as of the wave dispersion law. The results obtained show a good agreement with the ground truth.
The geochemistry of inorganic germanium in natural waters
Authors: Froelich Philip N. , Hambrick Gordon A. , Andreae Meinrat O. , Mortlock Richard A. , Edmond John M.
Published: February 2008

We present the initial results from a survey of the distribution of dissolved inorganic germanium in rivers, in the oceans, and in hydrothermal vents and plumes. In the ocean, germanium cycling mimics that of silica, since siliceous organisms incorporate Ge as a trace constituent in biogenic opal. The vertical and horizontal distributions of Ge concentrations in seawater are thus identical to those of silica (Ge/Si ∼ 0.7 × 10−6) and reflect uptake into and dissolution from the frustules of siliceous organisms. Germanium enters the ocean via dissolution of continental and seafloor silicates. The naturally weathered flux from continents to oceans carries a dissolved Ge/Si atom ratio in rivers of about 0.7×10−6, which reflects the ratio in average continental granites. Rivers draining industrial regions with significant coal combustion are contaminated with Ge leached from fly ash particles, resulting in Ge/Si ratios up to tenfold above the naturally weathered background. The flux to the oceans via high‐temperature alteration of seafloor basalts (hot springs) produces a Ge anomaly in hydrothermal plumes over the East Pacific Rise crest (20°S). Combining the observed Ge and 3He anomalies in plumes with 3He/Si observations in hot springs suggests that the Ge/Si hydrothermal flux to the oceans is about 4×10−6, near the ratio for average oceanic basalts (∼2.6×10−6). Vent effluents from the Galapagos hot springs measured directly display Ge/Si ratios of 16×10−6, suggesting that the ratio is variable between vent fields. Metalliferous sediments accumulating on the EPR crest (17°S) are enriched in germanium, suggesting that a fraction of the hydrothermal germanium source on the rise crest is scavenged into these rapidly accumulating iron and manganese hydroxyoxide phases.
A review of mixture theory with applications in physical oceanography and meteorology
Authors: Kirwan A. D.
Published: February 2008

The motivation for this paper is the observation that most problems in physical oceanography and meteorology are concerned with mixtures of two or more constituents. Some diverse examples include seawater, turbidity currents, deforming seabeds containing pore fluids, and air containing all phases of water. In the last 15 years a revolution has occurred in the theoretical continuum approach to mixtures; however, none of this has found its way into the oceanographic or meteorological literature. Thus it is appropriate to compare models arising from this modern approach with the classical results. The major distinction between the two approaches is that the modern theory stipulates equations of motion for each constituent, whereas in the classical result it is assumed that the equations of motion for the mixture suffice for a description of the dynamics. The ramifications of this are explored in several diverse areas in oceanography and meteorology. It is shown that for the hydrothermal‐dynamic description of seawater for purely dynamical purposes the distinction is not important. It is not as clear that this is true for models of fine and microscale processes. The principal difficulty seems to be the parameterization of mixing by Fickian‐type diffusion. Mixture theory provides an alternative that, for special situations, reduces to the Telegraph equation. For models of ocean seabed interactions it seems clear that the modern theory should be utilized. In this regard, some general dynamical models for sediment transport and turbidity currents and viscous porous seabeds are developed. Also, the thermodynamics of a mixture of ice, water vapor, and condensate in the atmosphere is treated from the standpoint of the modern theory.
Measurements of wave attenuation due to a soft bottom: The SWAMP experiment
Authors: Forristall George Z. , Reece Allan M.
Published: February 2008

The Sea Wave Attenuation Measurement Program (SWAMP) was designed to provide measurements of the attenuation of waves as they travel from deep water to relatively shallow water off the Mississippi Delta. The soft bottom was suspected of causing strong attenuation in the area. This effect has now been measured. A wave staff and electromagnetic current meter were used to estimate directional wave spectra at the Cognac platform in 312 m (1025 feet) of water and at platform VV in South Pass Block 27 in 19 m (63 feet) of water. In addition, measurements of vertical bottom motion were made at platform VV. Seven storm periods from Sepember 1979 to February 1981 were studied. The directional spectral comparisons showed that the theoretically calculated refraction and shoaling can explain the changes in the spectra when the wave height is low. However, as the wave height increases, a nonlinear attenuation mechanism becomes increasingly strong. The attenuation is a strong function of deep‐water wave height and a weak function of wave frequency. The bottom motion measurements showed that the bottom moved downward with small amplitude under wave crests.
Vernal circulation in the Gulf of Maine
Authors: Brooks David A.
Published: February 2008

The circulation in the Gulf of Maine has an important baroclinic component. It appears to be driven mostly by the density contrast between high‐salinity slope water which enters from the Atlantic and fresher waters which are formed in the Gulf or which enter from the Scotian shelf. Hydrographie surveys in three successive spring seasons suggest that slope water accumulates in Georges Basin, driving a counterclockwise surface circulation which brings Scotian shelf water westward into the Gulf and contributes to the eastward jet along the inner edge of Georges Bank. The slope water also crosses a sill and enters Jordan Basin, where it provides a potential energy source which may enhance a counterclockwise gyre partly driven by nearshore buoyancy sources and perhaps the wind. The coastal limb of the gyre turns offshore east of Penobscot Bay. Part of the separated coastal current recirculates in Jordan Basin, and part of it continues into Wilkinson Basin, generating a clockwise eddy as it passes over Jeffreys Bank. There is little evidence for recirculating surface flow in Wilkinson Basin. Instead, the surface water appears to split into branches feeding the Jordan Basin gyre, the Georges Bank jet, and an export path to Nantucket Shoals. The Jordan and Georges branches seem to be divided by the denser slope water in Georges Basin, and this may be the central process controlling the vernal intensification of the circulation in the Gulf. A more complete dynamical understanding awaits models which include the baroclinic influence of boundary waters.
Summer Arctic sea ice character from satellite microwave data
Authors: Carsey F. D.
Published: February 2008

In situ microwave data for the microscale properties of sea ice are combined with satellite data on the macroscale properties to construct an interpretation method for satellite data on sea ice for the warm season. Scatterometer, or calibrated radar, data give information on ice surface conditions, and radiometer data give information on areal concentrations of ponds and leads. The pond data are determined by examining fractional areas of exposed ice and using parameterized lead areas. These results are used to develop diffuse‐illumination surface albedo estimates for the time of maximum ponding, near day 195, and that of minimum ice cover, near day 258. The estimated ponding albedos range from 0.5 to 0.6, and ice cover minimum albedos range from 0.6 to 0.8. During summer, the 37‐GHz radiometer data are nearly independent of sea ice properties and are dominated by atmospheric and snow cover conditions. Lower‐frequency data are increasingly useful for interpreting ice conditions. Substantial anisotropy in backscatter is recorded in scatterometer data at 14 GHz, with surface resolution of 50 km showing 90° anisotropy in the 0.5–1 dB range. In Nimbus 5 and Seasat data, some variation in satellite‐recorded microwave properties during the period between 195 and 258 cannot be directly interpreted but are thought to be due to weather.
Ventilation of the deep northeastern Atlantic
Authors: Broecker Wallace S. , Rooth Claes , Peng Tsung‐Hung
Published: February 2008

Comparison of the 1973 GEOSECS expedition results from the deep eastern basin of the North Atlantic with those for 1981 TTO expedition reveal no firm evidence for change in NO3, PO4, or a H4SiO4. concentration. While a 2–3 μmol/kg difference is seen for O2, it is more likely experimental than temporal in origin. The combined TTO‐GEOSECS data sets reveal no evidence for ventilation of the bottom waters of the eastern basin by waters from the north.
Long‐range inversions for ocean acoustic tomography
Authors: Malanotte‐Rizzoli Paola
Published: February 2008

Ocean acoustic tomography was proposed by Munk and Wunsch (1979) as a method for making measurements of ocean variability over large areas. After the successful demonstration of the feasibility of the idea in the 1981 three‐dimensional mesoscale experiment (Ocean Tomography Group, 1982) the tomography group has proposed a new experiment to be carried out in 1986 in the eastern Pacific Ocean on ranges as long as the subtropical gyre scale. In this paper the gyre‐scale experiment is simulated in the model ocean, using Holland's eddy‐resolving general circulation quasi‐geostrophic model. The paper addresses the following issues: (1) measurement of the heat content vertical profile horizontally averaged along the tomographic section; (2) adequacy of the linearized inverse over very long ranges and the need for its improvement; (3) possible improvements in the specification of the field statistics to obtain more accurate estimates and to measure properties like average pycnocline trends; (4) relationship of possible range‐dependent information from the inversion to the assigned noise level. The results of the modeling simulation can be summarized as follows: (1) The linearized stochastic inversion needs to be improved for gyre‐scale ranges providing estimates of the average heat content that have warm or cold biases. Iteration is used and shown to provide good estimates of the average heat content. (2) A smaller number of iterations is necessary if the initial estimate is improved. This can be done by including a spatial mean in the horizontal covariance function for regions of the ocean where the energy level in the mean and in the long length scales may be even more important than the mesoscale energy peak. (3) General trends like average pycnocline slopes can be estimated very well by including an inhomogeneous covariance in the inversion. (4) The estimates of the mean heat content values and of the average slopes are rather insensitive to the specified noise level. (5) The type and number of eigenrays used is not a critical factor in the inversion estimates as long as the eigenrays provide a good sampling of the interior water mass. Increasing the number of eigenrays does not significantly improve the estimate of the average values. (6) Range‐dependent information is primarily a function of the assigned noise. For too high a noise the basic quantities that can be measured are the mean value and the average trend.
The signature of El Niño off Oregon, 1982–1983
Authors: Huyer Adriana , Smith Robert L.
Published: February 2008

Current and conductivity, temperature, and depth (CTD) measurements were made over the Oregon shelf near 43°N between February 1981 and April 1984 as part of a large‐scale west coast shelf experiment (SuperCODE). The data set includes a nearly continuous record of current velocity and temperature over the continental shelf off Coos Bay from May 1981 through January 1984, CTD sections off Coos Bay in January or February of each year from 1981 to 1984, and CTD sections off Newport (44.6°N) in April 1983, July 1983, and April 1984. The latter are compared with sections off Newport made during the previous two decades. Sea level from the Newport tide gage, daily sea surface temperature at Charleston (43.3°N), the alongshore component of the wind stress at 45°N and the large‐scale North Pacific atmospheric pressure pattern provide a climatological perspective. The initial manifestation of El Niño off Oregon was in October 1982: anomalously high sea level, high coastal sea surface temperature, and increased poleward flow. These effects occurred within 1 month of the onset of El Niño off Peru and preceded any local (North Pacific) atmospheric effect by 2–3 months. The anomalous local meteorological conditions, which became manifest in December and January, greatly enhanced the initial effects and inserted their own signal. The first signals of El Niño probably arrived by an oceanic path, but there is no doubt they were subsequently reinforced by anomalous atmospheric conditions.
Spatial and temporal patterns in pigment biomass in Gulf Stream warm‐core ring 82B and its environs
Authors: Smith R. C. , Baker K. S.
Published: February 2008

A chronology of the horizontal and vertical distribution of phytoplankton pigment biomass provides a biological life history of Gulf Stream warm‐core ring 82B. Development of ring 82B is followed through three distinct periods: a winter/early spring period of deep convective overturn with uniform and relatively high pigment concentrations to depths of 400 m, a late spring stratification period with subsurface (20–30 m) pigment maxima and relatively high ring center values compared to surrounding waters, and a Gulf Stream interaction period when ring characteristics are dominated by intrusions of low pigment concentration waters. While the ring maintains a unique identity throughout these periods of its life, prolonged deep vertical mixing as well as episodic interactions with its surroundings have a significant influence on pigment distributions within the ring. These interactions generally enhance pigment biomass compared to the water mass from which it is derived. A consistent feature of pigment distribution is the remarkable coherence between this measure of phytoplankton biomass and the corresponding physical hydrodynamic structure of the upper water column.
Comparative performance of AVHRR‐based multichannel sea surface temperatures
Authors: McClain E. Paul , Pichel William G. , Walton Charles C.
Published: February 2008

A brief outline of the basic concepts of cloud filtering and atmospheric attenuation corrections used in the Multi‐channel Sea Surface Temperature (MCSST) method is given. The operational MCSST procedures and products are described in detail. The comparative performance of AVHRR‐based MCSST'S is discussed via the use of the results of the JPL Satellite‐Derived Sea Surface Temperature workshops. For the four data periods there is surprisingly good correspondence in the sign and location of the major monthly mean SST anomaly features derived from MCSST's and those from a screened set of ship‐based SST's. With the partial exception of the one data period severely affected in some areas by volcanic aerosol from El Chichon eruptions, global statistical measures of the MCSST anomalies relative to the the ship data are as follows: biases, 0.3–0.4°C (MCSST lower than ship); standard deviations, 0.5–0.6°C; and cross‐correlations, +0.3 to +0.7. A refined technique in use with NOAA 9 data in 1985 has yielded consistent biases and rms differences near −0.1°C and 0.5°C, respectively.
Sea surface temperatures from the scanning multichannel microwave radiometer on Nimbus 7
Authors: Milman A. S. , Wilheit T. T.
Published: February 2008

Because of problems with the design and calibration of the scanning multichannel microwave radiometer (SMMR) on Nimbus 7, sea surface temperature (SST) algorithms had to be developed that corrected for instrument effects. Several stages of this development are reported here. The quality of the SST products from the final version is assessed. Thirty‐four months of data have been analyzed; the average SST error is about 1.12°C over the whole globe. The error is smaller in the equatorial region and larger in the northern oceans. The main source of error is due to heating of the SMMR instrument. Specific problems in the design of the instrument are discussed. The details of the SST algorithms are given in an appendix.
Temperature fine‐structure patches near an upper ocean density front
Authors: Marmorino G. O. , Rosenblum L. J. , Dugan J. P. , Shen C. Y.
Published: February 2008

Measurements with a towed thermistor chain have been used to map temperature fine‐structure variability along vertical sections through a frontal shear zone in the seasonal thermocline of the Sargasso Sea. Fine‐structure levels with 1–3 m horizontal wavelengths were normalized with local values of the vertical fine‐scale stratification to give values of normalized fine‐structure variance. Patches of increased levels of normalized variance were found to occur throughout the thermocline but were most extensive in the frontal zone where Richardson numbers (7‐m by 450‐m averages) were lowest (<1). The largest patches were 5–10 m in vertical extent and horizontally coherent over distances of several kilometers. Away from the frontal zone, patches tended to be smaller and were fewer in number. Simultaneous microstructure measurements along two depths were spatially correlated with the fine‐structure patches, implying that many patches were areas of increased mixing intensity. No consistent relationship was found between the patches and features in the vertical stratification, such as inversion zones or sheets and layers. Internal wave overturns on the scale of a few meters high by 10 m in the horizontal were found within the larger patches, suggesting that wave breaking, perhaps enhanced by the background shear, may be an ingredient in the formation or maintenance of some patches.
A note on the Charleston Gyre
Authors: McClain Charles R. , Atkinson Larry P.
Published: February 2008

The deflection of the Gulf Stream caused by a topographic feature—the Charleston Bump, located offshore of Savannah, Georgia—results in a quasi‐stationary cyclonic eddy—the Charleston Gyre which is situated over the continental slope east of Charleston and Cape Romain. Occasionally, the upwelling associated with this eddy produces an enhancement in the surface layer primary production that is great enough to be detected by the Nimbus 7 coastal zone color scanner (CZCS). In this note a CZCS image with simultaneous hydrography, current, and wind observations is presented that documents an unusual manifestation of the gyre. In addition to the CZCS image a Seasat synthetic aperture radar (SAR) image is included that clearly indicates the presence of the eddy adjacent to the Gulf Stream front.
Radon 222 in the benthic boundary layer
Authors: Sarmiento Jorge L. , Biscaye Pierre E.
Published: February 2008

A detailed survey of radon 222 and temperature profiles of the benthic boundary layer in the Hatteras Abyssal Plain shows a strong correlation between the structure of both. The apparent vertical diffusivities estimated from radon 222 are of the order of 50 cm2 s−1 in the mixed layer, and of the order of 1 cm−2 s−1 above it. One profile appears to have been taken in a frontal zone where isotherms dip sharply into the sediments. This is the only profile where there is significant penetration of radon above the mixed layer. Several other profiles suggest that the temperature may take longer than several radon half‐lives to adjust to new mixing and advection regimes. In such cases, one often sees considerable structure in the radon profile within the region where the potential temperature is well mixed.
An optical study of the water masses of the Gulf of Maine
Authors: Spinrad Richard W.
Published: February 2008

Optical studies of the suspended load in the Gulf of Maine have been performed in conjunction with hydrographic and biological analyses between late winter and early fall. Major particle sources are coastal runoff, benthic resuspension, and biological activity. Analysis of the optical efficiencies of the particles suggests that runoff and resuspension sources are restricted to the nearshore and shallow regions. The variabilities in the coupling and discoupling of the optical and hydrographic features of the Gulf demonstrate that advection is primarily responsible for the distribution of clear water masses, while settling, vertical mixing, and productivity are the processes behind the distribution of particles.
The necessity for a new parameterization of an empirical model for wind/ocean scatterometry
Authors: Woiceshyn Peter M. , Wurtele Morton G. , Boggs Dale H. , McGoldrick Lawrence F. , Peteherych Steven
Published: February 2008

This study reveals that the power‐law form of the Seasat A scatterometer system (SASS) empirical backscatter‐to‐wind model function (SASS 1), when combined with the sum‐of‐squares (SOS) wind retrieval algorithm, does not uniformly meet the instrument performance specification requirements. Analysis indicates that the horizontally polarized (Hpol) and vertically polarized (Vpol) components of the benchmark SASS 1/SOS wind retrieval system relating signal strength (backscatter) to wind speed yield self‐consistent results only for a small mid‐range of speeds at larger incidence angles and for a somewhat larger range of speeds at smaller incidence angles. An approach is presented that differs from previous calibration studies: here the internal Vpol versus Hpol consistency of the model is examined by the use of a set of pairwise collocated SASS‐produced winds, where one member of a wind pair (UVV) derives from only Vpol backscatter measurements and the other (UHH) from only Hpol measurements. This data set was created by extracting from the Seasat mission Geophysical Data Record (GDR) data base all pairs of SASS winds of the form (UVV, UHH) such that UVV and UHH are observations separated by no more than 5 min and 50 km. The set contains 377,289 such pairs. Comparisons of SASS 1/SOS derived wind data with wind data taken off the coast of Scotland during JASIN and with wind data from NDBO buoys off the U.S. Atlantic, Pacific, and Gulf coasts further underscores the shortcomings of the SASS 1/SOS wind retrieval system. These in situ wind comparisons to SASS indicate geographical differences in the retrieved scatterometer winds that are potentially attributable to environmental differences such as sea surface temperature. Taken together, the in situ comparisons to SASS, and the SASS Hpol to Vpol wind intercomparison indicate that the SASS 1/SOS wind retrieval system appears deficient in retrieving some winds, particularly from backscatter measurements made at higher incidence angles. We also find that Hpol backscatter measurements show greater sensitivity than Vpol backscatter measurements to wind speed variations above 10 m s−1, while the reverse holds for wind speeds less than 10 m s−1. It should be emphasized that it is the geophysical algorithms that lead to the errors cited here, not the instrumentation or the principles of scatterometry. In displaying these sources of error we have been obliged to outline the algorithmic methodology in a manner of presentation not previously attempted either in the published literature or in the voluminous code documentations. We hope that this material will be of value in itself to users of scatterometer data who seek to enhance their understanding of how such data are derived.
Mesoscale and synoptic scale features of North Pacific weather systems observed with the scanning multichannel microwave radiometer on Nimbus 7
Authors: Katsaros Kristina B. , Lewis Robert M.
Published: February 2008

Rain rates, wind speeds, and vertically integrated values of both atmospheric water vapor and cloud liquid water content were obtained from the brightness temperatures measured by the Scanning Multichannel Microwave Radiometer (SMMR) on the Nimbus 7 satellite during the winter of 1979. We examine their spatial relationship to wintertime midlatitude cyclones and a shortwave trough over the North Pacific Ocean as they approach the west coast of North America. Cold fronts are found to be located near the edge of the strongest gradient in integrated atmospheric water vapor. The rain rates exhibit patterns that bear a strong relationship both to the shortwave trough and to the cold fronts. Mesoscale features such as frontal undulations and rain cells are indicated in the rain rate data, even though the sensor resolution is marginal for such features. Rain rates are in reasonably good agreement with rain gage measurements on the coast. Furthermore, the onset of rain on the coast agrees with the timing found by simple advection of the SMMR observed rain areas, suggesting their possible future use in forecasting the timing of coastal rain events. Wind speeds ranging from 5 to 15 m/s in a region surrounding a cold front agree with surface observations. Cloud liquid water content exhibits patterns that are consistent with the frontal cloud patterns and with the analysis of the shortwave position.
Problems and future directions in remote sensing of the oceans and troposphere: A workshop report
Authors: Atlas David , Beal Robert C. , Brown Robert A. , De Mey Pierre , Moore Richard K. , Rapley Christopher G. , Swift Calvin T.
Published: February 2008

This paper attempts to identify the gaps and limitations in our ability to remotely sense the oceans and troposphere from air and space platforms. We set down the directions that offer solutions and new opportunities for advancing the state of the art. The needs are clearly related to the scientific problems. Special attention is given to the synergistic benefits of simultaneous observations because of the interdependence of the remotely sensed parameters and the problem areas to which they are directed. Emphasis is also given to the adaptation of spaceborne remote sensing to aircraft platforms and vice versa. The problem areas covered are (1) directional ocean wave spectra, (2) ocean surface winds, (3) ocean circulation, (4) sea ice, (5) a subset of atmospheric measurements, and (6) air‐sea interaction.
A diagnostic investigation of kinetic energy budgets in a numerical model
Authors: Hall Melinda M.
Published: February 2008

Data from a three‐layer quasi‐geostrophic eddy‐resolving general circulation model have been used to investigate the downstream convergence of kinetic energy in the model's analog of the Gulf Stream, as well as the kinetic energy budgets of the adjacent recirculation region. It is found that the downstream convergence of kinetic energy in the decelerating part of the jet is balanced primarily by ageostrophic flow against a pressure gradient, which may be interpreted as the sum of (1) a divergence of pressure work fluxes and (2) as conversion of kinetic to available potential energy in the region. In the western part of the recirculation there is an opposite tendency for conversion of available potential energy to kinetic energy, as this flow feeds the accelerating Gulf Stream. The analysis also suggests that instabilities are primarily barotropic in the decelerating jet region and baroclinic in the eastern recirculation regime. However, the two regions are coupled energetically, implying that a channel model enclosing the jet, thereby excluding energetic exchanges through its boundaries, may be inappropriate for investigating the instabilities of the jet.
Reduction of weather effects in the calculation of sea ice concentration from microwave radiances
Authors: Gloersen P. , Cavalieri D. J.
Published: February 2008

A technique is presented which improves existing methods of calculating sea ice concentrations from microwave radiances by reducing weather‐related effects over open ocean areas and in the vicinity of marginal sea ice zones. Winds, atmospheric water vapor, cloud liquid water, and rain increase the microwave emission over these regions and thus result in erroneous values of computed sea ice concentration. The method described is based on the microwave spectral properties of sea ice and ice‐free ocean and utilizes ratios of the polarized radiances at the 0.81‐cm (37 GHz) and 1.7‐cm (18 GHz) wavelengths. Following a discussion of the physical basis for this technique, examples are provided which demonstrate its utility. While the technique was developed for use with the Nimbus 7 scanning multi‐channel microwave radiometer data, it is applicable also to data from other microwave radiometers operating in a similar wavelength range.