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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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Journal ArticleDOI
TL;DR: In this paper, the authors present the observations of the ^3He-rich event of 2010 February 7, which was detected at all three spacecraft when they spanned 136° in heliographic longitude.
Abstract: A prevailing model for the origin of ^3He-rich solar energetic particle (SEP) events attributes particle acceleration to processes associated with the reconnection between closed magnetic field lines in an active region and neighboring open field lines. The open field from the small reconnection volume then provides a path along which accelerated particles escape into a relatively narrow range of angles in the heliosphere. The narrow width (standard deviation 60°. We present the observations of the ^3He-rich event of 2010 February 7, which was detected at all three spacecraft when they spanned 136° in heliographic longitude. Measured fluences of ^3He in this event were found to have a strong dependence on longitude which is well fit by a Gaussian with standard deviation ~48° centered at the longitude that is connected to the source region by a nominal Parker spiral magnetic field. We discuss several mechanisms for distributing flare-accelerated particles over a wide range of heliographic longitudes including interplanetary diffusion perpendicular to the magnetic field, spreading of a compact cluster of open field lines between the active region and the source surface where the field becomes radial and opens out into the heliosphere, and distortion of the interplanetary field by a preceding coronal mass ejection. Statistical studies of additional ^3He-rich events detected at multiple spacecraft will be needed to establish the relative importance of the various mechanisms.

136 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used homogeneity tests of long seasonal temperature series from Sweden, Denmark, Finland, and Norway indicate that homogeneous series are rare and that an abrupt change of the relative mean level is a much more common type of nonhomogeneity than a gradual change.
Abstract: Homogeneity tests of long seasonal temperature series from Sweden, Denmark, Finland, and Norway indicate that homogeneous series are rare and that an abrupt change of the relative mean level is a much more common type of nonhomogeneity than a gradual change. Furthermore, negative shifts were 20% more common than positive shifts. Homogenized temperature anomaly series that were constructed for six 5 degrees latitude x 5 degrees longitude grid boxes indicate that the temporal pattern of temperture changes has been similar in different parts of Sweden since 1861. The annual mean temperature over Sweden was found to have increased by 0.68 degrees C from the period 1861-1890 to 1965-1994. The corresponding changes for the seasons were: +0.18 degrees C (winter), +1.40 (spring), +0.42 (summer) and +0.60 (autumn). A direct comparson shows that non-homogeneities in the temperature series from individual grid boxes in a global data set can be as large as the total changes observed. We estimate that a 95 per cent confidence interval for the error, due to non-homogeneous long station records, in estimates of hemispheric temperature changes over land regions since the period 1861-1890 is +/-0.1 degrees C for the Northern Hemisphere and the globe and +/-0.25 degrees C for the Southern Hemisphere. For a region consisting of about five grid boxes, this error is +/-0.5 degrees C. The large non-homogeneities in individual grid-box series in the global data set is partly a consequence of the fact that homogeneous climate data are not always easily available for the open research community. We urge that efforts are made to improve this situation.

134 citations

Journal ArticleDOI
TL;DR: SMS-1 infrared brightness was estimated subjectively for each 1° square for the area from the equator to 20°N latitude and from 10°E to 30°W longitude for Phase III of GATE and the previous interphase period at 6 h intervals as discussed by the authors.
Abstract: SMS-1 infrared brightness was estimated subjectively for each 1° square for the area from the equator to 20°N latitude and from 10°E to 30°W longitude for Phase III of GATE and the previous interphase period at 6 h intervals. Each grid square was assigned one of the following brightness categories: 0, no clouds or clouds with low tops; 1, clouds with tops at middle heights; or 2, clouds with coldest tops—presumably of convective origin. The percentage of area covered by category 2 clouds was then computed for squares 3° an a side. The data were filtered with respect to time to isolate 3–4 day period wave-related oscillations. In addition, over 160 individual cloud clusters, including a special type of “squall” cluster, were identified in the IR images and tracked on a 3 h basis. A progressive pattern of 3–4 day period fluctuations in convective activity was observed. A comparison of this pattern with time-filtered 700 mb wind data indicates a correspondence of convective activity to wave trough a...

134 citations

Book ChapterDOI
01 Jan 2001
TL;DR: In this paper, the absolute accuracy in estimating latitude (as defined by physical constraints) that is achievable using the astronomical equations is addressed, and a new approach is proposed to minimize the variability of latitude estimations.
Abstract: Methods to calculate an animal’s position from light-level data collected by archival tags (geolocation by light levels) have been employed by wildlife researchers and the engineers who design the tags for over a decade. The problem of estimating longitude proved easy to solve, but accurate latitude estimates remain elusive. This paper addresses the absolute accuracy in estimating latitude (as defined by physical constraints) that is achievable using the astronomical equations and offers a new approach to minimize the variability of latitude estimations.

134 citations

Journal ArticleDOI
01 Jul 2003-Icarus
TL;DR: In this paper, the authors used a simple application of classical tidal theory to identify the dominant tidal modes and obtain results consistent with those of General Circulation Models and hence complements them.

133 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023240
2022432
202142
202042
201960
201851