FN Archimer Export Format PT J TI Shore and bar cross-shore migration, rotation, and breathing processes at an embayed beach BT AF BLOSSIER, B. BRYAN, K. R. DALY, C. J. WINTER, C. AS 1:1;2:2;3:1,3;4:1; FF 1:;2:;3:;4:; C1 Univ Bremen, Ctr Marine Environm Sci, MARUM, Bremen, Germany. Univ Waikato, Coastal Marine Grp, Fac Sci & Engn, Hamilton, New Zealand. Inst Univ Europeen Mer, UMR 6538, LGO, Plouzane, France. C2 UNIV BREMEN MARUM, GERMANY UNIV WAIKATO, NEW ZEALAND UBO, FRANCE UM LGO IF 3.337 TC 25 UR https://archimer.ifremer.fr/doc/00638/75014/75649.pdf LA English DT Article DE ;embayed beach;nearshore sandbars;beach rotation;beach breathing;coupled behavior;EOF analysis AB A principal component analysis (PCA) is used to decompose data on the coupled morphodynamics of the shoreline and nearshore sandbar of a typical single-barred embayed beach (Tairua Beach, New Zealand). Dynamic patterns are classified into simultaneous modes, where the bar and shoreline move at the same time, and nonsimultaneous modes, where the shore moves independently from the bar, and vice versa. Two simultaneous modes accounting for 65% of the variance of the shoreline and barline dominate the system. One mode describes inverse shoreline and sandbar cross-shore migrations (alongshore averaged), occurring with simultaneous rotations in the same direction. The other mode accounts for migration in the same direction accompanied by variations of the barline curvature (similar to 'breathing modes' previously described in embayed beach shoreline modeling studies). Two nonsimultaneous modes of lesser importance account separately for independent shoreline and barline rotations (10 to 15% of the variance explained). A PCA applied to the shore and sandbar behaviors modeled by four standard equilibrium models simulating shore and sandbar cross-shore migrations and rotations show that these are interrelated because of a correlation between wave energy and direction. Shore and bar rotations are coupled partially because the shape of the bay induces a correlation of their respective drivers, the wave angle of incidence and the alongshore gradient of wave energy. However, this correlation depends on the wave energy. This, in combination with different shore and sandbar response times (quantified using the models), also explains the independent rotations reflected by the nonsimultaneous modes. PY 2017 PD OCT SO Journal Of Geophysical Research-earth Surface SN 2169-9003 PU Amer Geophysical Union VL 122 IS 10 UT 000415149000001 BP 1745 EP 1770 DI 10.1002/2017JF004227 ID 75014 ER EF