Longitude

About: Longitude is a research topic. Over the lifetime, 2260 publications have been published within this topic receiving 54988 citations. The topic is also known as: angle of longitude.

Orographic Precipitation Modeling with Multiple Linear Regression

Abstract: A multiple linear regression (MLR) model, in conjunction with Geographic Information Systems technology, was used to derive the relationship between annual precipitation and elevation, longitude, and latitude. The island of Crete, in Greece, was used as the case study. A multiscale precipitation analysis was performed on areas ranging from large areas (the whole island and the northern, southern, and eastern parts of the island), to medium areas (watersheds), to small areas (sub-basins). While the MLR annual precipitation estimates (which used elevation, latitude, and longitude information) were found to be more reasonable than estimates obtained using elevation only when applied to the whole island, the difference between the MLR estimates and the elevation-only estimates was smaller when applied to individual watersheds. The MLR provides realistic estimates for mean areal precipitation for the island of Crete: 700±100, 950±150, and 1,300±200 mm for dry, average, and wet years, respectively. Elevation-ra...

Palaeomagnetic record of a late Tertiary field reversal

Abstract: summary. A palaeomagnetic record of a field reversal has been obtained from the Tatoosh intrusion in Mount Rainier National Park (latitude 46° 50° N, longitude 121° 45′W). fie VGP before and after the reversal is conformable with the North American polar wander curve. The reversal in direction is preceded by a decrease in intensity of the NRM of more than an order of magnitude. Immediately prior to the reversal the dispersion of the directions of magnetization increases. The reversal in direction is accomplished by a convoluted VGP path which traverses the Pacific and is somewhat confined in longitude. Subsequent to the completion of the change in direction the field intensity recovers, so that the intensity change takes at least twice as long as the directional change. The definition of the reversal plane in the Tatoosh intrusion gives the orientation of the cooling front at the time the reversal took place. An analysis of the cooling history of the body, in conjunction with the magnetic results, suggests that the body did not cool by simple conduction, and that convective heat transfer by meteoric water is important. This defines a two-stage cooling of the margin. At high temperature rapid cooling takes place as the water chills the hot rock. Later the circulating water in the cracked permeable margin maintains a moderate temperature for long periods. Long vertical cores from the intrusion have revealed a palaeomagnetic record similar to present secular variation records and suggests that some tens of metres of core from intrusive similar to the Tatoosh could give important resolution records of the geomagnetic field. A second reversal record was obtained from the Laurel Hill intrusion near Mount Hood, Oregon (latitude 45° 20′N, longitude 121° 4′W) which is approximately 10 Myr younger. The smoothed VGP paths for the two reversals are essentially identical. Other RN paths from North America appear to favour the Pacific, although the Lake Tecopa record of the last reversal is a notable exception. In comparing all available reversal paths, one finds that although individual paths are confined in longitude, no longitude is uniquely preferred nor does the site uniquely determine a path longitude. There is some preference amongst RN paths to favour the Pacific and the NR the Euroasian landmass, but the limited distribution of observation sites precludes a satisfactory distinction between site control or absolute control in geographical coordinates. Dominantly quadrupolar transitional fields are consistent with the records. Such fields are predicted by a variant of the Steenbeck Krause α2 DC dynamo, but αω dynamos may also exhibit quadrupolar transitional fields as indeed does the Sun. Some stationary nonaxisymmetric component is required to explain non-zero declination of the observed transitional fields.

Man-made e.l.f./v.l.f. emissions and the radiation belts

Abstract: Morphological studies of e.l.f./v.l.f. emissions on the Ariel III and IV satellites indicate that man-made electromagnetic emissions, namely power-line harmonics generated in the industrialised regions of North America and, also, v.l.f. transmissions at 17.8 kHz (NAA) and 16.0 kHz (GBR) in the longitude sector which encompasses the South Atlantic Anomaly, are responsible, at least in part, for the formation of the electron slot (2

Transient eddies in the southern hemisphere of Mars

Abstract: [1] Mars Global Surveyor is providing the first observations of transient eddies in the southern hemisphere of Mars. We derive basic properties of the traveling eddies that appear in midwinter (Ls = 134°–148°) through analysis of radio occultation measurements at 67°–70°S latitude. The dominant mode has a period of ∼2 solar days and a zonal wavenumber s = 3. Strong zonal variations in eddy amplitude signal the presence of a possible “storm zone” at 150°–330°E longitude. Within this longitude band the eddies achieve peak amplitudes at the 300-Pa pressure level of ∼7 K in temperature and 10–15 m s−1 in meridional wind speed. The minimum temperature associated with the eddies is ∼2 K colder than saturation of CO2, close to the threshold where nucleation and growth of new ice particles can occur. A simulation by a Mars general circulation model produces traveling eddies that closely resemble the observations.