On the Heat Budget for Mount Hope Bay

Abstract

A simple heat budget has been constructed for Mount Hope Bay (MHB) for two one-month periods: winter 1999 (February–March) and summer 1997 (August–September). The box model considered here includes the heat contributions to MHB from the Brayton Point Power Station (BPPS), the exchange across the air–water interface, the Taunton River, and the tidal exchange between MHB and both Narragansett Bay and the Sakonnet River (NB/SR). Comprehensive measurements of MHB temperature fields by Applied Science Associates, Inc., and meteorological data from T.F. Green Airport (Warwick, RI) were used to estimate the different heat flux component contributions. The box model results for winter show that the BPPS heating is balanced (within the uncertainty of the estimates) by air–water cooling alone. The simple winter balance does not hold during the summer, when heat losses due to tidal exchanges between MHB and NB/SR are important. The summer heat budget of MHB—including BPPS heating, air–water cooling and tidal exchange cooling—can be balanced (within the uncertainty of the estimates) by assuming that 3% of the colder NB/SR tidal input water is exchanged with the warmer MHB water during each tidal cycle. The air–water cooling accounts for 84.4% of the total cooling, and the tidal exchange accounts for 15.6% of the total cooling. Taunton River contributions to the heat budget were negligible in both seasons. Analyses show that the model temperature is most sensitive to uncertainty in the measurements used to estimate the air–water heat fluxes—the relative humidity in particular. Thus, local MHB measurements are important for accurate monitoring of the MHB heat budget in the future.