Based on the physics of Newton and Laplace, the big brass tide-predicting machine designed by Lord Kelvin was crucial for the success of the Normandy invasion in World War II. Along the entire French coast of the English Channel the vertical range from low tide to the next high tide exceeded 6 meters. At low tide those large tidal ranges exposed long stretches of beach that Allied soldiers would have to cross under heavy German fire. German Field Marshal Erwin Rommel, believing the Allies would therefore have to carry out their amphibious assault at high tide, built thousands of underwater obstacles in the intertidal zone, positioned so as to be covered by midtide and, unseen, rip out the bottoms of Allied landing craft. But Allied aerial reconnaissance spotted the obstacles and recognizing their purpose changed their invasion plan, making its success even more dependent on accurate tide predictions.
The talk will describe the history of our understanding of the tide since ancient times and the development of the tide prediction techniques that resulted in the creation of a brass analog tide predicting machine made up of dozens of gears and pulleys. Its use in making the tide predictions for the secret amphibious landings on the beaches of Normandy will be detailed, including the story of how the harmonic constants put on the machine were developed, and how accurate the predictions were on that fateful day that began the freeing of Nazi-occupied Europe in the spring of 1944. Dr. Parker will end the talk by putting tide prediction and its special nature in the context of other aspects of marine prediction and the greater difficulty in predicting storm surges, waves (and rogue waves), tsunamis, El Nino, and climate change.
Bruce Parker is the former Chief Scientist of the National Ocean Service in NOAA, and is presently a Visiting Professor at the Center for Maritime Systems at the Stevens Institute of Technology. He has a Ph.D. in physical oceanography from The Johns Hopkins University. Dr. Parker is the author of the recent book The Power of the Sea - tsunamis, storm surges, rogue waves, and our quest to predict disasters, which includes the story of the tide predictions for D-Day and a history of tide prediction. He is also the former Director of the Coast Survey Development Laboratory, former Director of the World Data Center for Oceanography, a former Principal Investigator for the NOAA Global Sea Level Program, and at one time ran the U.S. national tides and currents program. His awards include the U.S. Department of Commerce Gold Medal and Silver Medal, the NOAA Bronze Medal, and the Commodore Cooper Medal from the International Hydrographic Organization.
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