摘要:

Experiments involving the production of impulse corona of both polarities within a cloud of droplets atomized from a solution of glycerin and water are described. The observed charging of droplets with radii in the range 2.5 to 15 μ is characterized by a maximum surface charge density that is nearly constant down to about 6 μ and increases for radii below that if other electric and geometric parameters are fixed. The largest surface charge densities observed for droplets with radii above 6 μ are approximately 4×10−6coul m−2for positive corona and −6×10−6coul m−2for negative corona. Our results suggest quite different charging mechanisms for the two corona polarities. With positive corona the droplet charging appears to result from direct interaction between the positive streamers and the droplets. These findings indicate a possible link between the lightning discharge and subsequent rapid cloud

ISSN:0148-0227    

DOI:10.1029/JC075i024p04483

年代:1970

数据来源: WILEY

摘要:

The concentration of atmospheric ions with mobilities above a given value (for example, small ions) can be measured by using a cylindrical capacitor with a segmented electrode where the difference between the segment currents weighted with their reciprocal effective lengths is proportional to the concentration. An experimental arrangement based on this principle is described. The capacitor is furnished with an electrostatic shield to compensate for effects of stray fields. The weighted current difference is measured by a differential electrometer and can be directly recorded. Concentrations can be measured with an accuracy varying from 2.5 to 5%.

ISSN:0148-0227    

DOI:10.1029/JC075i024p04491

年代:1970

数据来源: WILEY

摘要:

Measurements of the charges on individual airborne snow particles showed that they were distributed approximately symmetrically between positive and negative values. The majority of the small charges were negative, however, and the majority of the large charges were positive. The magnitudes of the positive (or the negative) charges tended to follow a log‐normal distribution. The mirror image relationship between the sign of the net charge carried by precipitation and the sign of the atmospheric potential gradient was generally found to hold, but some exceptions were noted. Even in the exceptional cases, however, changes in the atmospheric potential gradient affected the distribution of charge

ISSN:0148-0227    

DOI:10.1029/JC075i024p04499

年代:1970

数据来源: WILEY

摘要:

A description is given of an airborne turbulent flux measurement system consisting of fast response sensors to measure two components of the relative wind velocity, temperature, humidity, and aircraft motion. Its performance and attendant data reduction schemes are illustrated with some data obtained during the Barbados oceanographic and meteorological experiment (Bomex) in May 1969. The nature of typical Bomex data is discussed, using spectra and cospectra obtained through this airborne sensor system.

ISSN:0148-0227    

DOI:10.1029/JC075i024p04506

年代:1970

数据来源: WILEY

摘要:

A wind‐blown water surface can be characterized in terms of a traveling correlation function in which the group and phase velocities are given by the values at the frequency of maximum spectral energy density. The two‐dimensional (space and time) surface displacement correlation function has been measured for low‐divergence wind‐blown waves in a laboratory tank. The measured phase and group velocities of the correlation function agreed with theoretical values for the peak frequency water‐wave component when the measurements were transformed to coordinates that had the velocity of the surface (drift) current. This description, which may be useful in the ocean as well, has recently been used to predict the temporal correlation of sound scattered from a model sea of known three‐dimensional surface correlation function (Clay and Me

ISSN:0148-0227    

DOI:10.1029/JC075i024p04519

年代:1970

数据来源: WILEY

摘要:

Two distinct mechanisms are known to produce positive space charge over the sea. They are the jet‐drop process produced by the bursting of bubbles at the air‐sea interface and the electrode effect, which is the result of the interaction between the geoelectric field and atmospheric ions. There has been uncertainty as to the relative importance of these mechanisms in the electrification measured in beach areas. An experiment was performed on the east coast of Barbados in which atmospheric space‐charge density and potential gradient were measured both inside and outside the surf zone. An abrupt change in both space‐charge density and potential gradient was always observed upon traversing the surf zone, indicating that an amount of positive space‐charge density, at least comparable in magnitude to that associated with the electrode effect outside the zone, was produced inside the zone by the surf. Measurements of Aitken nuclei, conductivity, and small ion density on the shore do not indicate that additional ionization took place in the surf and there were not enough natural small ions available to account for the space charge. These findings led to the conclusion that the bulk of the space charge probably resided on particles that originally left the surf zone by means of the jet‐d

ISSN:0148-0227    

DOI:10.1029/JC075i024p04525

年代:1970

数据来源: WILEY

摘要:

Formation of the Blake outer ridge by differential deposition of sediment on a relatively flat‐lying floor (horizon A) is discussed on the basis of the hydrodynamic interaction of two oppositely directed currents, which are decelerated in the interaction zone and diverted to a final direction taken to be the trend of the Blake outer ridge. If one or both of the currents carry sediment, deposition occurs preferentially in the region of decelerated flow, so that sediment distribution is governed by the steady‐state velocity field. Streamlines and isotachs computed from a model of two‐dimensional streamline flow are found to be consistent with the known sediment distribution; they require upstream current widths in substantial agreement with estimated widths of the Florida Current and the Western Boundary Undercurrent. The results suggest further that the Florida Current contributes relatively coarse sediment; the undercurrent, very fine sed

ISSN:0148-0227    

DOI:10.1029/JC075i024p04530

年代:1970

数据来源: WILEY

摘要:

Many of the recent high‐resolution seismic reflection profile data substantiate the depositional nature of the Blake‐Bahama outer ridge and show that its sedimentary structure is quite complex. The structure is revealed principally by the configuration of two prominent acoustic reflectors observed above horizon A, which are referred to as reflectors X and Y. Layer A‐X is shown to have been deposited preferentially along the ridge axis; thus, the over‐all shape of the ridge was established. Two major sedimentary regimes are distinguished above reflector X: a “northern” regime, which mantles the crest of the northern half of the ridge, and a younger “southern” regime, which laps onto the northern and creates sharp unconformable contacts in some localities. The most important of these contacts divides the regimes at latitude 30°15′N and suggests that the post reflector X depositional history of the ridge north and south of this lat

ISSN:0148-0227    

DOI:10.1029/JC075i024p04539

年代:1970

数据来源: WILEY

摘要:

The δ18O range inGlobigerinoides rubrafossils in a Sigsbee knoll core indicates a temperature range of about 5°C for the Gulf of Mexico during the Pleistocene age. By use of the empirically determined temperature dependence of δ13C of photosynthetically fixed carbon and by use of observed values for various sediment cores, a temperature range up to 35°C is suggested. A greater contribution of terrestrially derived light organic carbon during the cold relative to the warm periods may explain the anomalous carbon‐isotope‐derived paleotemperature range for the Gulf of

ISSN:0148-0227    

DOI:10.1029/JC075i024p04557

年代:1970

数据来源: WILEY

摘要:

Constituents of the marine atmosphere were collected on shallow trays exposed to onshore winds on the windward coast of the Island of Oahu. Upon addition of distilled water to the trays the collected materials formed organic monomolecular films on the water surface, and the curves for film pressure versus area for these films were determined at the field site. The monolayer studies indicated the presence of weakly surface‐active organic compounds and hydrocarbons as well as strongly adsorbed, highly polar species. Simultaneous collections of oceanic particulate matter were made with a high‐volume air sampler with glass fiber filters. The organic material was extracted from the filters with chloroform and analyzed for specific fatty acids by gas chromatography. The ratios of the quantities of the principal fatty acids found in the air samples were similar to previously reported fatty acid ratios from sea surface samples collected at the air‐sea interface. It was concluded that the ocean appears to be a major source of airborne maritime organic matter. The implications of these data to sea fog and haze stabilization are disc

ISSN:0148-0227    

DOI:10.1029/JC075i024p04561

年代:1970

数据来源: WILEY