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on measurements of the tide at churchill, hudson baySince the late 1990s the semi-diurnal tide at Churchill, on the western shore of Hudson Bay, has been decreasing in amplitude, with M(sub 2) amplitudes falling from approximately 154 cm in 1998 to 146 cm in 2012 and 142 cm in 2014. There has been a corresponding small increase in phase lag. Mean low water, decreasing throughout most of the twentieth century, has levelled off. Although the tidal changes could reflect merely a malfunctioning tide gauge, the fact that there are no other measurements in the region and the possibility that the tide is revealing important environmental changes calls for serious investigation. Satellite altimeter measurements of the tide in Hudson Bay are complicated by the seasonal ice cover; at most locations less than 40% of satellite passes return valid ocean heights and even those can be impacted by errors from sea ice. Because the combined TOPEX/Poseidon, Jason-1, and Jason-2 time series is more than 23 years long, it is now possible to obtain sufficient data at crossover locations near Churchill to search for tidal changes. The satellites sense no changes in M(sub 2) that are comparable to the changes seen at the Churchill gauge. The changes appear to be localized to the harbour, or to the Churchill River, or to the gauge itself.
Document ID
20170002390
Document Type
Reprint (Version printed in journal)
Authors
Ray, Richard D.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
March 21, 2017
Publication Date
February 10, 2016
Publication Information
Publication: Atmosphere-Ocean
Volume: 54
Issue: 2
ISSN: 0705-5900
Subject Category
Earth Resources and Remote Sensing
Report/Patent Number
GSFC-E-DAA-TN40261
Distribution Limits
Public
Copyright
Other