Topic
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.
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TL;DR: In this article, high-level balloon data from the region of western Europe through North America to eastern Asia were used to investigate disturbances in the summertime stratosphere from 27-36 km.
Abstract: High-level balloon data from the region of western Europe through North America to eastern Asia were used to investigate disturbances in the summertime stratosphere from 27–36 km. Systematic diurnal variations were found, with amplitudes up to 2 m sec−1, but the patterns were more complex than would be expected from simple tidal theory. Traveling planetary waves were also found at these altitudes, propagating westward at 30° of longitude per day. The waves were detected as periodic oscillations in the u component, with amplitudes up to 4 m sec−1, extending from 25–45N, and from 25–45 km in the vertical. A solution to the barotropic vorticity equation was found which possesses many of the observed features when applied to 10 mb (31 km) data. While it is suspected that both the diurnal wind patterns and the traveling waves are forced by tropospheric disturbances, the causes of neither could be determined.
16 citations
01 Jan 1999
16 citations
TL;DR: In this article, simultaneous measurements of neutral winds from the Doppler shifts of the 15867 K (630. nm) emission of the night sky have been made at two midlatitude stations separated by about 26° in longitude and less than 1° in latitude.
Abstract: Simultaneous measurements of neutral winds from the Doppler shifts of the 15867 K (630. nm) emission of the night sky have been made at two midlatitude stations separated by about 26° in longitude and less than 1° in latitude (39.8° N, 105.5°W and 40.13° N, 79.16°W). Comparison of the measured winds show strong local time correlation and negligible universal time correlation, in particular for meridional winds. This behavior is expected for the thermosphere for solar-minimum, magnetically quiet conditions, when the strongest pressure forces driving the winds are caused by insolation. The results also show the basic assumption of longitudinal or zonal averaging of two-dimensional thermospheric models to be correct for at least the 26° longitudinal separation between the two stations.
16 citations
TL;DR: In this article, it is shown that the cold temperatures associated with the inversions lead to an enhancement in the mean zonal wind in a localized area near the pole, and that this enhancement makes the mean flow barotropically unstable.
Abstract: Infrared and radio observations of the upper cloud region of Venus indicate that the north polar region contains features of large thermal contrast. A cold collar, encompassing a region of temperature inversions, lies between latitudes of about 65 and 75 deg, and a pair of warm features, separated by about 180 deg of longitude and centered near 80 deg latitude, rotate about the pole with a period of about 2.9 days. It is shown that the cold temperatures associated with the inversions lead to an enhancement in the mean zonal wind in a localized area near the pole, and that this enhancement makes the mean flow barotropically unstable. Since data for this region are limited, a model for the thermal structure has been used for calculating growth times and phase periods of the unstable modes. Choosing model parameters to agree as closely as possible with available data, it has been determined that the rotating warm features are likely to be manifestations of barotropically unstable waves.
16 citations
TL;DR: In this paper, the root mean squares (rms) of the adjusted differences, grouped within 2° latitude by 2° longitude boxes, are mapped for the western boundary current regime and adjacent Antarctic Circumpolar Current segment for each southern hemisphere ocean, as well as for the eastern Indian Ocean, where sufficient crossover data are available.
Abstract: GEOS 3 altimeter data are adjusted to minimize differences at the intersections or crossovers between ascending and descending orbits. This procedure removes noise created by orbital uncertainty and permits study of sea level variations without knowledge of the geoid. The root mean squares (rms) of the adjusted differences, grouped within 2° latitude by 2° longitude boxes, are mapped for the western boundary current regime and adjacent Antarctic Circumpolar Current segment for each southern hemisphere ocean, as well as for the eastern Indian Ocean, where sufficient crossover data are available. The rms crossover values are compared to surface-based hydrographic data studies of ocean transients for verification of the altimeter results. The altimeter data clearly reveal reasonable patterns of sea level transients associated with the western boundary currents and Antarctic Circumpolar Current. In addition, the rms values reveal regions of locally amplified tidal features adjacent to the Patagonian coast of Argentina and in the region west of New Zealand. The altimeter data verify and expand on the results of limited surface-based data sets, particularly in the case of the circulation transients south of Madagascar, and southwest of New Caledonia. In the eastern Indian Ocean the altimeter data suggest variable sea level conditions near 10°–20°S, near 20°–30°S, and near 50°S. The last is associated with the Antarctic Circumpolar Current, but the source of the northern variable regions is not clear.
16 citations