Showing papers on "Longitude published in 1972"

Global Climatic Data for Surface, 800 mb, 400 mb: July.

Abstract: : The document is the second publication in the effort to gather, in one common format, the most representative global climatologies of certain seasonal meteorological variables. From selected data sources, the July global distributions of pressure, temperature, wind, and moisture are reconstructed for the three atmospheric levels. These data are supplemented by presentations of the global distributions of albedo, cloudiness, evaporation, precipitation, and selected elements of the surface heat balance. All data are interpolated at the 4-deg latitude by 5-deg longitude global grid used in the Mintz-Arakawa model. They are given in the form of both tabulated values and machine-analyzed maps.

On Determining the Electron Density Distribution of the Solar Corona from K-Coronameter Data

Abstract: The electron density distribution of the inner solar corona (r ⩽ 2 R ⊙) as a function of latitude, longitude, and radial distance is determined from K-coronameter polarization-brightness (pB) data. A Legendre polynomial is assumed for the electron density distribution, and the coefficients of the polynomial are determined by a least-mean-square regression analysis of several days of pB-data. The calculated electron density distribution is then mapped as a function of latitude and longitude. The method is particularly useful in determining the longitudinal extent of coronal streamers and enhancements and in resolving coronal features whose projections on the plane of the sky overlap.

Propagation of Pc 1 hydromagnetic waves across North America

Abstract: The apparent horizontal group velocity of hydromagnetic (hm) waves of natural origin near 1 Hz was found to be about 2.3 × 10³ km/sec from simultaneous measurements made in Hawaii, Alaska, Washington, Colorado, and Quebec. The signal seemed to move essentially westward into the dark hemisphere from the dawn terminator and showed a dispersion of about a 0.5-sec recurrence period per hertz emission frequency per degree longitude. Problems of computations of magnetospheric properties from the hm wave characteristics are discussed.

Venus: topography revealed by radar data.

Abstract: Surface height variations over the entire equatorial region on Venus have been estimated from extended series of measurements of interplanetary radar echo delays. Most notable is a mountainous section of about 3-kilometer peak height located at a longitude of 100 degrees (International Astronomical Union coordinate system). The eastern edge has an average inclination of about 0.5 degrees, which is unusually steep for a large-scale slope on Venus. The resolution of the radar measurements along the surface of Venus varied between about 200 and 400 kilometers with a repeatability in altitude determination generally between 200 and 500 meters. The mean equatorial radius was found to be 6050.0±0.5 kilometers.

Twenty-seven-day recurrences in the solar-wind speed - Mariner 2.

Abstract: Results of an autocorrelation analysis of the Mariner 2 data concerning solar-wind speed obtained in late 1962. A statistically significant correlation associated with the solar rotation has been found near a lag of 27 days; however, the amplitude of the correlation is only about 0.4, in essential agreement with measurements of Vela 2 and 3 during the period from July 1964 to July 1967. The relatively modest correlation is interpreted to mean that a number of speed structures observed by Mariner 2 did not endure for more than one solar rotation; those structures that did endure evolved significantly in shape, amplitude, and solar longitude from one solar rotation to the next. The analysis also shows that typical solar-wind structures occupied about 30 to 45 deg in solar longitude near 1 AU.

Magnetic-field anomalies in the lunar wake.

Abstract: The interplanetary magnetic field is only slightly perturbed by the presence of the moon in the solar wind flow. A statistical study of umbral increases and of penumbral variations was conducted with respect to variation in the solar wind plasma value beta, the distance from the moon, and the selenographic longitude of the limb regions of the lunar surface in the solar wind flow. All lunar wake anomalies show a strong positive correlation with the plasma value beta, while only penumbral increases show a marked variation with distance from the moon. There is no clear correlation of penumbral anomaly occurrence with selenographic longitude of the exposed lunar limb in the solar wind flow.

Periodicities in the longitude distribution of sunspots.

Abstract: It is well known to the observer of sunspots that the spots seem not to be randomly distributed on the solar surface but rather occur at an increased rate at distances of 180° of each other on the same hemisphere while northern and southern hemispheres are independent. The following investigation - based on observational data of rotations No. 1457–1568 (1962–1970) shows four main results:

POGO observations of the equatorial electrojet

Abstract: During intervals in 1967 to 1970, the OGO-4 and 6 spacecraft made over 2000 traversals over the equatorial electrojet in the altitude range 400-800 km when local times were between 9 and 15 hours. These spacecraft carried total field magnetometers making measurements to an accuracy of 2 gamma with a sample rate greater than once a second. Delta F values, the deviations from these observations, were formed from an internal reference model. The results were plotted for a 30 deg band about the equator, and the characteristics of the electrojet effect in the data were investigated. This effect was characterized by a sharp negative V-signature of some 16-19 deg in width and a variable amplitude. The position of this minimum was found to lie within 0.5 deg of the dip equator. A slight northward shift was noted at the longitude of Huancayo. The jet amplitudes were normalized to 400 km amplitudes and observed to be highly variable in time. Amplitudes over the longitude range 50 to 90 deg W averaged 60% higher than elsewhere, as expected, due to the weaker main field. However, though the scatter of amplitudes is high, the expected minima in east Asia was not evident. It was speculated that this could be due to a less conducting upper mantle in this area.

Planetary Pressure Wave of 4- to 5-Day Period in the Tropics

Abstract: Surface pressure data during the Inter- employed. The phase spectrum shows that the 4 to national Geophysical Year period for 76 stations in the 5-day oscillations result from a westward moving wave tropical zone 20°N-200S have been examined to investi- having a periodicity of 4-5 days and wave number 1. gate the propagation characteristics, if any, of the 4- to The direction of propagation is identical in both hemi- 5-day pressure oscillations. Cross-spectrum analysis with spheres and shows no inclination to latitude circles. a first-difference filter and the Tukey window has been In a recent paper, Misra (1971) presented evidence for the global scale of an atmospheric pressure oscillation of 4- to 5-day periodicity. A plot of the phase difference against the longitude difference for stations arranged in zonal belts demonstrates the existence of a westward propagating wave having periodicity of 4-5 days and wave number 1. The wave was earlier evidenced in an analysis by Wallace and Chang (1969), who used data for a few stations north of the Equator. The present paper examines more closely the behavior of this wave propagation in the tropical zone 20°N-200S.

Ionospheric Shock Front from Apollo 15 Launching

Abstract: IONOSPHERIC perturbations observed at Fort Monmouth, New Jersey, over a distance of more than 1,200 km following the launch of Apollo 14 were attributed1 to the arrival of an atmospheric shock front which splits2 at ionospheric heights into ion acoustic and normal acoustic modes. An opportunity to repeat these observations was provided by the launching of Apollo 15 on July 26, 1971, at 0834 EST. Ionograms were taken at our station (74: 07:52 W longitude; 40:23:25 N latitude). Ionograms taken simultaneously at Wallops Island (75:29 W longitude; 37:51 N latitude) were made available by courtesy of National Oceanic and Atmospheric Administration (NOAA). We converted all ionograms to true-height.

Latitude determination from calculated azimuth and observed altitude

Abstract: It may be required to determine the astronomical position of a place for surveyor other purposes. The commonly accepted methods for latitude make use of meridian or near meridian stars; ex-meridian methods are used for longitude and for azimuth. Since the formula for calculating azimuth is a function of latitude, it can be used to determine the latitude if the true azimuth is already known, and this could be described as an ex-meridian method for latitude.

A Nomogram for Look Angles to Geostationary Satellites

Abstract: TA chart is presented that allows for the rapid determination of the azimuth and elevation to a geostationary satellite, given the satellite longitude and the latitude and longitude of the ground site.

Some Aspects of the Day‐to‐Day Variability of the Equatorial Anomaly: American and Japanese Sectors

Abstract: The day-to-day variability observed in the structure of the equatorial anomaly during a period of high solar activity is investigated. Using hourly values of ƒ0F2 observed at a number of ionosonde locations in the American and Japanese longitude sectors during 1958, the structure of the equatorial F2 region has been obtained on an hourly basis for an entire year. It is observed that the equatorial anomaly shows considerable day-to-day fluctuations in both its structure and its diurnal development. The anomaly is generally best developed in the evening hours, and day-to-day changes in the time of best development are typically on the order of 2 to 4 hr. It is observed that the time when the anomaly attains its maximum development is not the same on both sides of the magnetic equator, although this time is closer to coincidence during the equinoctial months than during the solstices. Also during the equinoctial months, the anomaly crests tend to be more symmetric about the equator than during the solstices. The relative magnitudes of the crests display a noticeable changeover with time during the northern solstice in both longitude sectors. The crest on the winter side of the magnetic equator is larger during the day, and the summer crest is larger at night. The exact time that this changeover occurs varies on the order of 5 to 7 hr on a day-to-day basis. During the southern solstice this crest changeover is observed only in the Japanese sector.

Air Motions in the Tropical Stratosphere Deduced from Satellite Tracking of Horizontally Floating Balloons

Abstract: Between June and November of 1970, 26 constant level balloons were released from Ascension Island (8 S) for flight at 30 and 50 mb. The balloons were positioned by the Interrogation, Recording and Location System (IRLS) aboard the Nimbus D satellite. In general, balloon positioning appeared to be accurate to within a few kilometers, although occasionally there was doubt as to whether the balloon position was to the right or left of the satellite subtrack. Eight of the flights at 50 mb and three of the flights at 30 mb were tracked for more than one month, and one 50 mb flight was tracked continuously for more than 5 months while making 7 circumnavigations of the Earth. From the satellite-determined 12-hourly balloon positions in the tropics, 223 smoothed 24-hour-average zonal and meridional winds were obtained at 30 mb and 693 such winds were obtained at 50 mb. Near the equator the balloons moved from east to west at a speed of about 23 ms−1 at 50 mb and 28 ms−1 at 30 mb, while undergoing a mean northward drift of approximately 0.1 ms−1. The northward drift was a maximum in the Northern Hemisphere winter, suggesting a weak upward extension of the Hadley Cell to 50 mb. Superimposed on this drift were oscillations in meridional velocity of about 2-month period, with these oscillations also most pronounced in the Northern Hemisphere winter. Small (1–3 ms−1) short-period fluctuations in meridional velocity were evident directly above the equator at 50 mb. These waves appear to move westward at speeds of 30–40 ms−1 and to have a wavelength of about 90° longitude. They were responsible for transporting small amounts of westerly momentum into the winter hemisphere. Fluctuations in zonal velocity (Kelvin waves) were also delineated by flights near the equator. These waves appear to move eastward at speeds of 30–40 ms−1 and to have a wavelength of 360° longitude. Some comparisons are made between these IRLS data and the data obtained from GHOST balloon flights at the same heights in early 1969.

Large-Scale Magnetic Fields and Activity Patterns on the Sun

Abstract: The recent results concerning the large-scale magnetic field and solar activity distribution are summarized. The static characteristics for three types of such large-scale features are given: (a) Giant regular structures (super-supergranules) are probably the largest elements in the hierarchy of solar convective cells, which can be defined in the solar atmosphere for example, by magnetic field patterns, faculae, calcium flocculi, and the organization of active regions, (b) Active longitudes are the longitude sectors with grouped activity and concentrated magnetic fields. The grouping lasts in the same sector for many successive rotations. These active longitudes may have different rates of shift in heliographic longitude per rotation in a given system of coordinates. They are demonstrated not only on magnetic synoptic charts arranged by latitude zones but may also be followed on Zurich Heliographic Maps of the Photosphere for at least four cycles. This means that the organization of activity and fields in streams or active longitudes does not change during several tens of years and proceeds in the same way following the same rules of development, (c) Active latitudes may also play a role in the formation of large-scale patterns.

Spatial Variations in Atmospheric Predictability

Abstract: Calculations are made with the NCAR six-layer general circulation model to determine the time evolution of errors initially confined to a region 4000 km in diameter superimposed upon real global data. Three experiments are made to distinguish between the effects of an error located initially on the northern or southern sides of the jet stream or in the tropical area. Results show that the largest error centers generally evolve in the jet stream; however, the propagation rate is much less than advection effects would suggest. Coverage of the Northern Hemisphere is accomplished as much by propagation across the north pole and via the tropical belt as it is via the jet stream. It is not complete even after seven days. As a whole the tropics are more sensitive than the middle latitudes to initial errors. Cross-equatorial effects are most pronounced at and just east of the initial longitude of the error.

Initial development of the June 1971 South Equatorial Belt disturbance on Jupiter.

Abstract: Photographs taken with the Catalina 61-inch reflector from June 21 through July 10, 1971 have permitted study and measurement of early developments of a major South Equatorial Belt (SEB) disturbance. High resolution photographs of the disturbance were obtained on seven nights during the 19-day interval. The first photograph at 04:38 UT on June 21 recorded the initial outbreak at 79.5 deg longitude (System 2), and -14 deg Zenographic latitude. From this point, dark spots moved along the SEBs towards increasing longitude. The preceding white spot had an initial period of 9h54m32.5 tor-3.5s, and retrograding dark spots on the SEBs a mean period of 9h58m30s.5 tor- 7s. The feature from which all the spots emerged had a rotation period of 9h55m29s tor- 2.5s, and is close to the System 3 radio period of 9h55m29.73s tor- 0.04s derived by Carr.

Solar Activity in McMath Region 10789 During Disk Passage, 12 to 15 June 1970.

Abstract: : Less than half a dozen longitude-identified active regions in the (current) 20th sunspot cycle produced 90 or more solar eruptions during disk passage. Besides a high flare-burst productivity, each of these was identified with energetic particle emission. A recent one of these regions was centered aroung longitude 226 degrees (17 degrees N latitude) in McMath region 10789, with central meridian passage on 16.8 June 1970. It is shown that the region which spawned an unusually high burst-to-flare ratio on 13 June had the maximum radio brightness at both 10.7 and 20 cm lambda in this brief interval. (Author Modified Abstract)