Generation of harmonics by sea breeze in nontidal water bodies

The sea breeze introduces harmonics of its diurnal cycle into water bodies, which can be notable for strong sea breeze and microtidal and nontidal con ditions. The harmonics can be of the same magnitude as those produced by bo ttom friction and dominate those produced by nonlinear terms in the equatio ns of motion. A closed-form analytic solution of the linearized depth-avera ged equations of motion including friction is discussed for the situation o f a sea breeze blowing on an idealized one-dimensional basin of constant de pth. The solution reveals the generation of odd harmonics introduced by the quadratic wind stress and role of (linearized) friction. Sea-breeze forcin g on the idealized basin is numerically modeled, and agreement with the ana lytic solution is found. The numerical model is then run with quadratic bot tom friction and nonlinear terms to compare relative contributions to the g eneration of harmonics. Harmonics of the water motion are distinguished as forced, or arising from the wind forcing, and as response, or arising from the interactions within the water. The hydrodynamics of Baffin Bay, Texas, are modeled and spatial variation and relative strength of the harmonics in vestigated. Baffin Bay is a large shallow embayment with a weak connection to the Gulf of Mexico that experiences a strong southeast wind and sea bree ze during the summer. The wind induces even and odd forced harmonics throug h the combined quasi-steady southeast wind and sea breeze. At Baffin Bay, r atios of the semidiurnal to diurnal amplitudes of water level and current s peed are found to be comparable to M-4/M-2 ratios for U.S. Atlantic coast e mbayments.