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.

Measurements of inner zone electron precipitation

Abstract: Energetic electron (≳0.16 MeV) data taken from November 1972 to April 1973 from over 1000 passes of a low-altitude (∼750 km) noon-midnight polar-orbiting satellite across the L=1.75 field line in both the northern and southern hemispheres have been analyzed for evidence of the longitude and local time distributions in electron precipitation on that field line. The precipitation processes were observed to be weak, at least near local noon and midnight, as evidenced from the negligible fluxes observed at all pitch angles when the conjugate point is below sea level and from the absence of any direct observation of electrons at L=1.75 in the bounce loss cone at all longitudes. By observing quasi-trapped fluxes with a spectrometer having a large geometric factor, a high sensitivity was achieved for detecting electron precipitation and measuring the energy spectra with fine resolution. The data have been analyzed and found to show that prounounced precipitation events near local noon and midnight were a rare occurrence between ∼60°E and ∼100°E. In the ∼100°E to ∼180°E longitude region, significant fluxes of quasi-trapped electrons were often observed with a very pronounced noon-midnight asymmetry. The quasi-trapped fluxes observed locally in this region were often large near midnight but seldom significant near noontime. At longitudes east of 180°E, to the western edge of the South Atlantic Anomaly, the local noontime fluxes of quasi-trapped electrons displayed an abrupt increase and, on the average, were higher than the midnight intensities. In this region the energy spectra of quasi-trapped electrons observed at midnight displayed L-dependent peaks less often than those observed at noontime. These very pronounced longitude and local time variations in the quasi-trapped population provide conclusive evidence that the effectiveness of the electron precipitation mechanism(s) is dependent upon local time, (although without further information, detailed local time distributions in the precipitation mechanisms were not derived). From the electron data it was found that within a given local time and longitude interval the fluxes were widely variable, indicating that the precipitation mechanism(s) were not steady in time. Also, during the time period of observation, the average intensities of the quasi-trapped electrons were higher at times of high negative Dst.

Satellite observations of the Wenchuan Earthquake, 12 May 2008

Abstract: The Wenchuan Earthquake (latitude 310˚ N, longitude 1034˚ E), magnitude 79 according to the United States Geological Survey (USGS) and 80 according to the Chinese Meteorological Authority, occu

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)

Assimilation of Mars Global Surveyor atmospheric temperature data into a general circulation model

Abstract: We examined the observed temperature data from Thermal Emission Spectrometer (TES) between heliocentric longitude L_s = 141° and 146° (∼10 Martian days in northern summer) during the mapping phase, then compared them with the simulated results using the NASA/Ames Mars general circulation model Both show a strong polar vortex at the winter pole, higher equatorial temperatures near the ground and larger tropospheric lapse rates during daytime than at night However, the simulation is colder than the observation at the bottom and top of the atmosphere and warmer in the middle The highest wave activities are found in the polar front in both the simulations and the observations, but it is at a much higher altitude in the former Experiments show that larger dust opacity improves the temperature field in the lower atmospheric levels Using a steady state Kalman filter, we attempted to obtain a model state that is consistent with the observations The assimilation did achieve better agreement with the observations overall, especially over the north pole However, it is hard to make any further improvement Dust opacity is the key factor in determining the temperature field; correcting temperature alone improves the spatial and temporal variations, it degrades the mean state in the south pole Assimilation cannot improve the simulation further, unless more realistic dust opacity and its vertical profile are considered