Providential Tides: the Double Low Water of Narragansett Bay

We investigate a mechanism for producing double-lows and double-highs in the semi-diurnal tide by selective amplification of higher harmonics in a resonant gulf. A double low water is observed at Providence, RI, near the head of Narragansett Bay on days when there is a flattening of the low water tidal curve at Newport, at the mouth of the bay. The flattening is caused by an unusually large quarter-diurnal component to the tide at Newport. The quarter diurnal component has the right phase (a maximum close to the time of the minimum in the semi-diurnal tide) to produce a prolonged flattening of the tidal curve around low water. The natural period of Narragansett Bay (for quarter-wavelength resonance) is close to 4 h and the quarter diurnal tide is amplified, relative to the semi-diurnal tide, within the bay. The selective amplification of the higher harmonic further prolongs the flattening effect at Providence and, occasionally, is sufficient to create a double low water at the head of the bay from quarter and semi-diurnal tides alone. More often, though, a sixth-diurnal harmonic produced within the bay, added to the flattened low water at Providence, creates the double low water. This mechanism of selective amplification of tidal harmonics could be relevant to double tides elsewhere

Crystal constructions in Number Theory

Weyl group multiple Dirichlet series and metaplectic Whittaker functions can be described in terms of crystal graphs. We present crystals as parameterized by Littelmann patterns and we give a survey of purely combinatorial constructions of prime power coefficients of Weyl group multiple Dirichlet series and metaplectic Whittaker functions using the language of crystal graphs. We explore how the branching structure of crystals manifests in these constructions, and how it allows access to some intricate objects in number theory and related open questions using tools of algebraic combinatorics

Cross-shoreface Suspended Sediment Transport : A Response to the Interaction of Nearshore and Shelf Processes, Fall 1994 Duck, NC Field Experiment

Deployment : The tripods were assembled, tested and secured onboard the RIV Sea Diver, which left the Little Creek Amphibious Base in Norfolk, Virginia early on 26 September. While underway to the deployment site, the continuous surface water conductivity and temperature survey was run and several CTD casts were made. The tripods were deployed on 26 September and secured to the sea floor with sand anchors by VIMS divers. The R/V Sea Diver then began the series of on/off shore transects at the tripod deployment site for approximately 12 hours. The vessel returned to port on 27 September . Recovery: The tripod recovery cruise began late on 21 October and repeated the underway data collection scheme of the September cruise. On October 22 divers removed the sand anchors and the tripods were recovered without incident. The on/off shore transects were repeated and transit to port occurred on 23 October