Local energy exchanges in a shallow, coastal lagoon: Winter conditions

A 110-day time series of estuarine water temperature is used to verify a numerical model of local air-water heat exchanges under winter conditions in a shallow, bar-built estuary on South Florida's Atlantic coast. Quasiperiodic frontal passages during the winter of 1977–1978 produce cycles of heating and cooling over time scales of about a week. Temperatures decrease 4–7°C during the first few days following frontal passages. Model results suggest that the daily net water temperature change is most strongly correlated with, and therefore primarily in response to sensible and latent heat fluxes. Heating by insolation and cooling by longwave radiation are substantial, but in both cases the correlation with the net daily temperature change is not statistically significant. Conductive exchanges with the underlying sediments appear to play a minor role in the estuarine heat budget. The root-mean-squared error of simulated water temperatures asymptotically approaches a value of approximately 10°C for time intervals of between 2 and 30 days.