Showing papers on "Longitude published in 1969"

Solar Activity and Recurrences in Magnetic-Field Distribution

Abstract: A study of the Mount Wilson magnetic-field synoptic chart material divided into latitude zones for the interval 1959–67, and a comparison of the data with sunspot groups have provided a better understanding of the structure of the background-field pattern and its relation to activity. The interaction of old and new fields within the pattern seems to result in long-lived sections of alternating polarity in both hemispheres. We postulate subsurface sources with rotation periods of about 27 days which produce active regions over a longitude zone of some tens of degrees. There is a tendency for the background-field features with strong fields to resist to some extent the shearing effects of differential rotation. A prediction is made concerning the nature of the interplanetary magnetic field above the ecliptic.

Bathymetric Atlas of the Northcentral Pacific Ocean

Abstract: : The atlas contains 41 bathymetric charts covering the NOrtheastern Pacific Ocean between 4 degrees S and 60 degrees N latitude and from 140 degrees W longitude eastward to the American continental mainland. Sea floor relief is shown by means of 200-fathom contours based on a mean sound velocity of 4800 feet/second. Where sufficient data permits, the 100-fathom and 20-fathom contours are shown. Principal sounding lines used in compilation and analysis of the sea floor relief are indicated by a subdued grey overprint on each chart. The scale of the charts is approximately 1:4,500,000. (Author)

Crustal structure of Northwestern Ontario: Refraction seismology

Abstract: Deep seismic sounding of the earth's crust has been carried out between latitudes 49°30′ N and 51°30′ N, from longitude 93 °W to longitude 96 °W, by means of a refraction survey, using energy from underwater explosions. A two-layer crust was found, with velocities uniform both laterally and vertically within the layers. Velocities found were: Pg = 6.05 ± 0.05 km/s; Sg = 3.46 ± 0.05 km/s; P* = 6.85 ± 0.05 km/s; S* = 4.00 ± 0.05 km/s; Pn = 7.92 km/s; Sn = 4.60 ± 0.08 km/s. The discontinuity separating the crustal layers (called the Intermediate discontinuity) is believed to be similar to the Conrad discontinuity. Contour maps of depths to this discontinuity and the Mohorovicic discontinuity were produced. Average depths (below surface) are: Intermediate = 18.25 km; Mohorovicic = 34.28 km. Average surface elevation is 0.33 km. Velocity averaged vertically through the crust has a mean value over the area of 6.36 km/s. Structures on the discontinuities are related to at least one major surface geological featu...

Studies of auroral hydrogen emissions in west–central Canada. III. Proton and electron auroral ovals

Abstract: A chain of patrol spectrograph stations was operated from 1964 to 1965 to cover the geomagnetic latitude range 55° to 78 °N near geographic longitude 100 °W. Absolute intensities of hydrogen alpha and the OI(λ 5577) lines have been derived from over 7500 spectrograms. From this data, average Hα and λ 5577 zenith intensities, as a function of geomagnetic latitude and time, were derived. Results are also given for these averages for different ranges of Kp index. Plots were made of the λ 5577 intensities from which estimates of the night glow and proton-excited components had been subtracted. It was found that the center of the proton auroral oval lies a few degrees equatorward of that of the electron oval before midnight and crosses somewhat poleward of it after 0100 hours geomagnetic. The average proton and electron precipitation zones overlap considerably. With increasing magnetic disturbance, the proton precipitation zone spreads equatorward and increases considerably in its peak intensity, although its ...

The climate of Gobabeb

Abstract: The Namib Desert Research Station in South West Africa is situated at Gobabeb on the northern bank of the dry Kuiseb River some 60 miles southeast of Walvis Bay and about 35 miles from the Atlantic coast. The geographical coordinates are: Latitude 23i?½ 34' S; Longitude 15i?½ 03' E ; Height above mean sea level 407 m (1335 ft.).

North Polar, South Polar, World Maps and Tables of Invariant Magnetic Coordinates for Six Altitudes: 0, 100, 300, 600, 1000, and 3000 KM.

Abstract: : North Polar, South Polar, and World Maps showing constant invariant geomagnetic latitude lines (at 5 degree intervals except for some midlatitude regions) and constant invariant geomagnetic longitude (at 10 degree intervals) are presented for 6 altitudes; 0, 100, 300, 600, 1000 and 3000 km. Tables of data resulting from calculations of geomagnetic field lines which give the locations of even 5 degree intervals of invariant latitude and even 10 degree intervals of invariant longitude are given. The invariant geomagentic coordinates, the decisions involved in setting up the invariant longitude system and the special features used in the design of the maps and tables are described. (Author)

Gulf Stream thermal gradients from satellite, ship, and aircraft observations

Abstract: Details of the surface horizontal temperature structure of the Gulf Stream are delineated by satellite infrared measurements. Comparisons of satellite results with ship and aircraft data confirm major features of the pattern but do not confirm most of the fine-scale details. The effects of system noise and cloud interference are reduced by analysis of average or high values within half-degree latitude/longitude areas.

A model midnight meridian magnetospheric field.

Abstract: Magnetospheric field configuration in midnight meridian, considering cavity boundary surface and trapping region currents and tail sheet current

Gravity anomalies over the Aleutian Trench

Abstract: In 1964 the USC&GS Surveyor crossed the Aleutian trench 48 times between 165° and 180°W longitude. The data provide a basis for a free-air gravity map, a Bouguer gravity map (density 2.87 gm/cm3), and three possible crustal models that fit the results and available seismic data. The area covered lies west of an earlier gravity survey described by Peter, et al. [1965] of the Aleutian trench between 155°W and 165° longitude and 53° and 55°N latitude. As on the earlier gravity survey, which was also carried out by the U.S. Coast and Geodetic Survey, the observations were made along north-south lines spaced 20 km apart and extending about 200 km south of the island arc.

Crustal structure in Northwestern Ontario: Regional magnetic anomalies

Abstract: A regional aeromagnetic map, portraying the regional magnetic anomaly system in Northwestern Ontario west of longitude 92 °W and south of latitude 55 °N and extending westward into Manitoba to longitude 97 °W (with an additional block bounded by latitudes 54° N and 56 °N and longitudes 97° W and 102 °W) is presented. The map was prepared by multiple application of a two-dimensional smoothing operator applied to data digitized at 3 km intervals from the 1-inch-to-1-mile aeromagnetic map series published by the Geological Survey of Canada. Comparison was made with previous maps overlapping on portions of the area, which had been made by various techniques, including Fourier analysis, fitting of 6th-order polynomials, and photographic reduction. The general features of the anomaly system were found to be similar for all of these techniques. The regional anomaly system is found to be related in some cases to the thickness of the upper crustal layer (defined as lying above the Intermediate seismic discontinuit...

Airborne Magnetic Data across the Tasman Sea

Abstract: THIS communication describes a search for linear magnetic anomalies1 in the Tasman Sea which might indicate present or previous episodes of seafloor spreading. The Tasman Sea lies between eastern Australia and New Zealand, and in this study its boundaries are denned as 20° and 45° S latitude, 145° and 175° E longitude (Fig. 1).