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, the effects of 10 climatological and persistence variables (latitude, maximum wind speed, 12-h change of maximum wind speeds, longitude, distance to land, Julian date, sea surface temperature, speed of movement, zonal component of motion, and meridional components of motion) on changes of intensities of tropical cyclones over the eastern North Pacific Ocean were examined for the periods 1982-87 and 1988-93.
Abstract: The effects of 10 climatological and persistence variables (latitude, maximum wind speed, 12-h change of maximum wind speed, longitude, distance to land, Julian date, sea surface temperature, speed of movement, zonal component of motion, and meridional component of motion) on changes of intensities of tropical cyclones over the eastern North Pacific Ocean were examined for the periods 1982–87 and 1988–93. Backward multiple regressions were performed to relate these 10 variables to changes in maximum intensity (as determined by wind speed) over periods ranging from 12 to 72 h. Latitude, maximum wind speed, and the 12-h change of maximum wind speed were the most significant variables. Each of the 10 variables was statistically significant at the 95% level at one or more of the time periods. Speed of movement, the component of motion, and the meridional component of motion were the least significant factors. The statistical relationships were tested using independent data from 1994. The mean absolut...
15 citations
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TL;DR: In this paper, a total of 108 separate TDIM simulations for different ionospheric conditions were used to elucidate the high-latitude ionosphere trends and show the UT dependence and spatial variability of the ionosphere.
15 citations
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TL;DR: In this paper, the changes in intensity of the nucleon and meson components of cosmic rays during a cruise of the Canadian Naval Icebreaker Labrador into the Arctic, through the North West Passage, and circumnavigating the North American Continent were measured.
Abstract: Measurements have been taken on the changes in intensity of the nucleon and meson components of cosmic rays during a cruise of the Canadian Naval Icebreaker Labrador into the Arctic, through the North West Passage, and circumnavigating the North American Continent. The geomagnetic latitudes covered extend from 18°N. to 89°N. The latitude knee is clearly shown at a geomagnetic latitude of about 52° in the case of the nucleon component and less definitely between 40° and 50° in the case of the meson component. The rigidity of particles arriving in a vertical direction at 52° is 2.1 Bv. and at 45° is 3.7 Bv. Meyer and Simpson have shown that changes in the primary spectrum between 1948 and 1954 probably extend up to these rigidities and such changes should, therefore, be observable at sea level. The longitude effect at low latitudes is clearly shown by differences in intensity between the measurements on the east and west sides of North America. In the case of the meson component, the magnitude of the longit...
15 citations
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TL;DR: In this paper, upper air data obtained from 32 equatorial stations, 1973-87, show that 70 mb wave intensity over the Maritime continent varied annually with largest amplitude in NH late winter and spring, but the seasonal cycle of intensity was not uniform in the tropics.
Abstract: Meridional wind oscillations of 3-6 day period are common in the equatorial lower stratosphere. Upper air data obtained from 32 equatorial stations, 1973-87, show that 70 mb wave intensity over the Maritime continent varied annually with largest amplitude in NH late winter and spring, but the seasonal cycle of intensity was not uniform in the tropics. Time series of meridional velocity and its spatial coherence suggest that 70 mb wave packets were local in longitude and episodic in time.
15 citations
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TL;DR: In this article, the authors examined the four-peaked structure in the observed topside ion density and its manifestation as longitudinal structures in total electron content (TEC) over South America and found that the TEC in the whole latitude distribution is larger over the east coast than over the west coast of South America.
Abstract: [1] Recent observations of the low-latitude ionospheric electron density revealed a four-peaked longitudinal structure in the equatorial ionization anomaly when plotted at a constant-local-time frame. It was proposed that neutral wind-driven E region dynamo electric fields due to nonmigrating tidal modes are responsible for this pattern. We examine the four-peaked structure in the observed topside ion density and its manifestation as longitudinal structures in total electron content (TEC) over South America. The strong longitudinal variation in TEC characterized by larger value over Brazilian eastern longitude sector as compared to that over the Peruvian western longitude is modeled using the Sheffield University plasmasphere-ionosphere model (SUPIM) aiming to identify the control factors responsible for the longitude variation. We found that the SUPIM runs using as input the existing standard models of vertical drift, and thermospheric winds do not explain the TEC longitudinal structure. Realistic values of these control parameters were generated based on the strong vertical drift longitudinal variation as determined from magnetometer and Digisonde data and appropriately adjusted winds (horizontal wind model). These realistic vertical drifts together with the modified thermospheric wind, when used as input to the SUPIM, are found to satisfactorily explain the longitudinal differences in the TEC and topside ion density (Ni) over South America. The study shows that the TEC in the whole latitude distribution is larger over the east coast than over the west coast of South America and that the vertical drift and thermospheirc winds control the longitudinal four wave structure in the TEC and Ni.
14 citations