Document Detail


Variability of observed low-altitude astronomical refraction (LAAR) from different geographic locations: progress toward a global map of LAAR variability.
MedLine Citation:
PMID:  16201426     Owner:  NLM     Status:  PubMed-not-MEDLINE    
Abstract/OtherAbstract:
The variability of the astronomical refraction of the setting Sun as measured from Holetown, Barbados, West Indies, is compared to sunset refraction measured from Edmonton, Alberta, during the same time of year. At about 13 degrees N latitude, Holetown experiences a marine tropical climate, while Edmonton (53 degrees N) has a subarctic continental climate. The 17 sunsets recorded from Holetown between 27 December 2003, and 21 February 2004, and between 25 and 30 December 2004, show a mean astronomical refraction of 0 degrees .475 and standard deviation of 0 degrees .012. The 26 sunsets recorded from Edmonton between 31 December 1992, and 17 February 1993, show a mean astronomical refraction of 0 degrees .699 and standard deviation of 0 degrees .118. The Barbados mean is significantly less than the Edmonton mean, while the variability of the Barbados data is an order of magnitude less than the Edmonton data. The variability of refraction appears to be strongly correlated with the variability in the surface vertical temperature gradient recorded on the same day as the sunset observations. This suggests that mapping of the geographic distribution of low-altitude astronomical refraction variability could be based on climatology of the surface vertical temperature gradient.
Authors:
Russell D Sampson; Edward P Lozowski; Hans G Machel
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Applied optics     Volume:  44     ISSN:  0003-6935     ISO Abbreviation:  Appl Opt     Publication Date:  2005 Sep 
Date Detail:
Created Date:  2005-10-05     Completed Date:  2005-11-15     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0247660     Medline TA:  Appl Opt     Country:  United States    
Other Details:
Languages:  eng     Pagination:  5652-7     Citation Subset:  -    
Affiliation:
Department of Physical Sciences, Eastern Connecticut State University, Willimantic, Connecticut 06226, USA. sampsonr@easternct.edu
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