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1.
The concentration of the KCl solution whose conductivity is that of standard seawater (35 ‰) at 15°C
The concentration of the potassium chloride solution (KCI) which has the same conductivity as15deg C at P79 standard seawater corrected to35.0000permil has been evaluated. The variation of the conductivity ratio of KCI solutions to standard seawater (35permil ) has been measured between 14.8 and15.2deg C for KCI solutions whose concentration varies from 32 to 33 g.kg-1. 相似文献
2.
The absolute electrical conductivity at15deg C of several lots of standard seawater has been measured with great precision as a function of chlorinity. Potassium chloride (KCI) solutions of known concentration and having almost the same conductivity were also measured and the concentration giving the same conductivity at15deg C as35.0000permil standard seawater (Chl =19.37394permil ) was found to be 32.4352 g/kg. 相似文献
3.
The ratiosR_{s,t,o} of electrical conductivity of seawater samples of precisely known salinity to standard seawater at the same temperature have been measured over a wide range of salinities from 0 to42permil S and over the full range of oceanic temperatures from -2 to35deg C. The samples withS<35permil were prepared by accurate weight dilution of standard seawater with distilled water. High salinity samples were prepared by fast evaporation of standard seawater and subsequent weight dilution into the already determined <35permil range. An equation was derived which expresses the S versusR_{s,t,o} relationship very precisely from1-42permil and at all temperatures, i.e.,S = f_{1}(R_{s,t,o}) + f_{2}(R_{s, t,o},t) =Sigma_{n=0}^{5} a_{n}R^{n/2}+ frac{Delta t}{1+kDelta t} Sigma_{n=0}^{5} b_{n}R^{n/2} whereDelta t = t-15deg C,R = R_{s, t.o} ; only the first termf_{1} is required at15deg C. The effeet of temperature on the electrical conductivity of standard seawater was also measured. The ratior_{t} of the conductivity at temperaturet to the conductivity at15deg C (C_{35,t, o}/C_{35,15,o} ) is very aeenrately expressed by a fourth degree equation int . i.e,r_{t}=Sigma_{n=0}^{4} c_{n}t^{n} These two equations are sufficient for all salinity determinations at normal atmospheric pressure. 相似文献
4.
An echo sounder has been developed with features ideally suited to oceanographic and fisheries research. Instruments commonly used for such research are inaccurate, limited in dynamic range, unstable, and generally inflexible. An effort has been made to overcome these deficiencies with the sonar system discussed here. The echo sounder to be described has a time-varied-gain receiver (20 log_{10} R or40 log_{10} R + 2alphaR ) accurate to withinpm0.5 dB over a 100-dB range. The equivalent dynamic range is 140 dB (the ratio of the maximum signal at minimum gain to the equivalent input noise at maximum gain in a 4-kHz bandwidth). The temperature stability ispm0.5 dB from10deg to35deg C at any range. Operating parameters, including frequency, can be easily altered to accommodate a variety of needs. 相似文献
5.
The paper describes a low-power barometer intended for remote weather stations, but also meeting the requirements for manned stations and airports, in which the condensation temperature of carbon disulphide (CS2 ) is used to determine the barometric pressure(p) . A heated cylindrical bulb with a re-entrant well for a thermistor through the bottom and an internal radiation shield is 1/3 filled with CS2 . Helical springs assist CS2 migration on wetted surfaces and allow liquid and vapor to pass one another in the small diameter exit-condenser tube. A miniature Dewar flask gives thermal insulation and a 0.01-mm beryllium-copper diaphragm transmits the external pressure. The condensation temperature is read with a simple Wheatstone bridge and dc amplifier giving an outputV_{0} = 0.5(p- 100 Pa) V. Pulsed power with the pulse length controlled by a second thermistor on the outlet tube is used for efficiency. Long term tests of a number of barometers have given power levels around 40 mW at20deg C and indicated maximum drifts ofpm50 Pa/year,pml0 Pa/day, andpm2 Pa short term. 相似文献
6.
The Practical Salinity Scale (PSS) 1978 is defined only for salinities within the range 2-42. We have investigated the relationship between mass-determined salinity, electrical conductivity, and temperature for salinities between 0 and 2 with the aim of developing an extension to the Practical Salinity Scale 1978. The paper presents our data, on the basis of which the following correction is proposed to extend the validity of the equations defining the scale to the entire 0-42 range:S=summin{i=0}max{5} (a_{i}+b_{i}f(t))R_{t}^{i/2}-frac{a_{0}}{1 + 1.5x + x^{2}}-frac{b_{0}f(t)}{1+y^{1/2} + y + y^{3/2}} wheref(t)=frac{(t-15)}{1 + k(t-15) x=400R_{t} y=100R_{t} and the constanta_{i}, b_{i} , andk are defind by the Practical Salinity Scale 1978. 相似文献
7.
Rationale for the measurement of open-ocean tsunami signatures are presented, and available pertinent data are reviewed. Models for tsunami signature and background noise are proposed in order to synthesize an optimum tsunami receiver. Using these models, the minimum tsunami amplitude (in cm) to yield the probability of correct tsunami detectionP_{D} = 0.999 and probability of false alarmP_{F} = 10^{-3} is found to be0.718/sqrt{f_{0}} , wheref_{0} is the tsunami dominant frequency (in cycles/h). A realizable receiver is proposed and its performance is evaluated using actual tsunami signatures. It is demonstrated that the detection of a tsunami with an average amplitude as small as 0.7 cm is possible for theP_{D} andP_{F} as above. Simulation results using synthesized background noise are shown. Tidal effects on the receiver performance also are considered and are found negligible for a certain range of the receiver parameters, resulting in a considerable reduction of the signal processing required. 相似文献
8.
Radar backscatter measurements from the ocean were made at 13.9 GHz from Skylab. The radar signal increased rapidly with wind speed over the entire range of winds encountered, and for angles of incidence of30deg and larger. Signals observed were normalized to a nominal incidence angle (from values withinpm2deg of the nominal) and to a nominal upwind observation direction, using a theoretical model that has been verified as approximately true with aircraft experiments. The wind speed was regressed against the resulting scattering coefficientssigma^{0} and the values ofbeta in windpropto sigma^{0beta} were obtained for incident angles of1deg , 17deg , 32deg , 43deg, and50deg , and for vertical, horizontal, and cross polarizations. For the three larger angles,beta varies from 0.3 to 0.6. Observations during the summer and winter Skylab missions were treated separately because of possible differences caused by an accident to the antenna between the two sets of observations. The results are in general agreement with the theory [26] in all cases, with the winter and cross-polarized agreement somewhat better than that for summer like-polarized data. The "objective analysis" method used for determining "surface-truth" winds in the Skylab experiment was tested by comparing results obtained at weather ships (using all other ship reports to produce the analysis) with the observations made by the weather ships themselves. In most cases, the variance about the regression line between objective analysis and weather-ship data actually exceeded that about the regression line between objective analysis and backscattcr data! 相似文献
9.
A new spectrum model for the ocean surface is proposed. We determine the two unknown parameters in this spectrum by fitting it to radar observations. We find that this spectrum combined with two-scale scattering theory can predict much of the observed dependence of the radar cross section on radar frequency, polarization, angle of incidence, and wind velocity at incidence angles in the0deg-70deg range. The spectrum model is combined with a model for swell to examine the effect of swell on the radar cross section. We find that the effect of swell is significant for low radar frequencies (L band) and near normal incidence but can be nearly eliminated by using higher frequencies (K_{u} band) and large angles of incidence (approx 50deg ). 相似文献
10.
Systems of identical precisely spaced bubbles or similar monopole scatterers in water-e.g., inflated balloons or thin-walled shells-insonified at frequenciesomega_{SR} dose to their fundamental radial resonanceomega_{0} (bubble) frequency may themselves display resonance modes or superresonances (SR's) [1]. Ordinary single-bubble resonances magnify the local free-field pressure amplitudep_{1} by a factor(ka)^{-1} ,a being the radius andk the wavenumber in water: for air bubbles or balloons in water, this factor is of the order of 70. Under SR conditions each member of the system amplifies the local free-field amplitude by a further factor of order(ka)^{-1} . Depending upon geometry and other constraints, the pressure fieldP_{SR} on the surface and in the interior of each scatterer will then be in the range of10^{3}p_{1} to5 times 10^{3} p_{1} . This paper investigates the sensitivity of this phenomenon to small departures from the ideal model. In particular, it examines the effect of small differences in scatter positioning and volumes in the context of an SR system consisting of two bubbles/balloons close to the boundary of a thin elastic plate overlying a fluid half-space. It is found that, to observe the SR phenomenon, radii and positions should be controlled to within approximately 1/2 percent.P_{SR} is also sensitive to the angle of incidence of the plane wave train. For the simple system examined here, this sensitivity is considerable for either flexural wave trains or volume acoustic waves incident upon the bubble/ balloon pair (doublet). Practical uses of the phenomenon may range from the design of passive high-Q acoustical filter/amplifiers and acoustical lenses to improved source efficiencies. 相似文献
11.
The author has developed a new thermometer with a time constant of about 0.5 ms as a part of his two-phase alternating current bridge. The thermometer permits the application of a Pt-wire with a low resistance of about 10-50 mOmega . A resolution of less than 0.001 K in the range of40deg C can be reached. Properties, experiments, and results from measurements with this fast thermometer are described. 相似文献
12.
Channel capacity in bits per joule 总被引：1，自引：0，他引：1
Underwater acoustic telemetry has a total input energy constraint, since the energy is stored in the transmitter's batteries. This work is primarily rephrasing the work in channel capacity in terms ofC_{J} bit/J as compared toC bit/s, to emphasize the energy efficiency and to deemphasize the speed of the telemetry. The energy channel capacityC_{J} , for any waveform channel with well-defined capacityC bit/s at signal powerS watts, is defined asC/S bit/J. It is shown that for coherent binary frequency shift keying (BFSK) and waveform channels, the supremum ofC_{J} overS is approached asS approaches zero. For the Gaussian channel the best coding uses narrow bands with the highest S/N. 相似文献
13.
The conductivity ratio of diluted and concentrated standard seawater has been measured very accurately in a salinity range from 0 to42permil and at temperature from -1 to30deg C. All the data have been fitted into polynomials which are compared with previous data. The specific conductance of seawater is deduced and a polynomial for the full range of salinity and temperature is proposed. Data presented in this paper have been used, with those of Dauphinee presented in this issue, to elaborate the new "Practical Salinity Scale 1978." 相似文献
14.
Dauphinee T. Klein H. Kirby C. Kathnelson J. 《Oceanic Engineering, IEEE Journal of》1983,8(4):288-292
A new portable salinometer has been developed which is based On a direct determination of the conductivity ratioR_{t} = (C_{x}/ C_{s})_{t} of sample(x) to standard(s) seawater in a dual-cell, continuous-flow system. The new salinometer requires only 10 ml of unknown and much less of standard, drawn from the source bottles through fine Teflon tubes, to obtain complete flushing and several repeat readings to the order ofpm0.001 , in salinity. The system is autobalancing over the full range of conductivity ratio from 0 to 1.3 and in the future will be direct reading in salinity units. The amount of standard water required is so low that standard water ampoules, at the rate of l/day, can be used as the source. The method used offers a possibility of a direct measurement of salinity in the ocean by measuringR_{t} in situ. 相似文献
15.
The history of the definition of salinity and the methods of computing It are traced from the beginning of the twentieth century until the present. Difficulties that have arisen in existing practices are discussed, in particular, the situation regarding reduction of in-situ CTD observations. The Practical Salinity Scale 1978 is an attempt to remove the shortcomings; it has been recommended for international acceptance. The basis for this new scale is an equation relating the ratio of the electrical conductivity of the seawater sample to that of a standard potassium chloride solution (KCI) at15deg C atmospheric pressure. The samples used were prepared from standard seawater diluted with distilled water or evaporated by weight. Finally, the set of new equations for CTD data reduction is given, based upon the work of authors whose papers are appearing elsewhere in this volume. 相似文献
16.
Microwave scattering signatures of the ocean have been measured over a range of surface wind speeds from 3 m/s to 23.6 m/s using the AAFE RADSCAT scatterometer in an aircraft. Normalized scattering coefficients are presented for vertical and horizontal polarizations as a function of incidence angle (nadir to55deg ) and radar azimuth angle (0deg to360deg ) relative to surface wind direction. For a given radar polarization, incidence angle, and azimuth angle relative to the wind direction, these scattering data exhibit a power law dependence on surface wind speed. The relation of the scattering coefficient to azimuth angle obtained during aircraft circles (antenna conical scans) is anisotropic and suggests that microwave scatterometers can be used to infer both wind speed and direction. These results have been used for the design of the Seasat-A Satellite Scatterometer (SASS) to be flown in 1978 on this first NASA oceanographic satellite. 相似文献
17.
《Oceanic Engineering, IEEE Journal of》1982,7(2):75-82
A triaxial set of underwater receiving coils was developed and tested. The receiving system was used jointly with an underwater, calibrated, horizontal, electric dipole source in studies of extremely low-frequency electromagnetic propagation. This paper discusses the electromechanical design of the receiver and tethering system and addresses system sensitivity and noise levels. The receiving system was used successfully in a series of measurements, in spite of serious motion noise contamination. A stationary system sensitivity of5 times 10^{-4} gamma/sqrt{Hz} was achieved. 相似文献
18.
《Oceanic Engineering, IEEE Journal of》2008,33(2):224-231
19.
During the West Coast Experiment in March 1977, a test was conducted to ascertain the effectiveness of using remote sensing techniques to estimate sea surface temperature (SST) from infrared (IR) emissions of the sea surface. Aircraft flights were made over three buoys moored in southern California coastal waters, and data was collected of sea surface emissions at thermal IR wavelengths (7.95-13.5 mu m). SST obtained from the remote sensing measurements were compared with in situ SST measured with thermistors mounted on the buoys. The remotely determined SST were from1.4-2.9deg C lower than the in situ measurements. Several factors are discussed that could account for the differences. 相似文献
20.
《Oceanic Engineering, IEEE Journal of》2009,34(1):83-92