Indirect Determination of Surface Heat Fluxes in the Northern Adriatic Sea via the Heat Budget

R.P. Signell (1), J.W. Book (2), H. Perkins (2), S. Carniel (3), J. Chiggiato (4), J. D. Doyle (5), J. Pullen (5), and A. Russo (6)


(1) U.S. Geological Survey, Woods Hole, MA
(2) NRL, Stennis Space Center, USA
(3) CNR-ISMAR Venice, Italy
(4) ARPA Emilia Romagna, Bologna, Italy
(5) NRl, Monterey, USA
(6) University of Ancona, Italy

Modelling the process of dense waters formation and spreading in the northern Adriatic Sea is a challenging task. As direct measurements of fluxes in such a large area are difficult to be carried out, meteorological models have to be employed in order to make information available about dominant winds, temperature, cloud conditions, etc. Part of the difficulty consists indeed in correctly determining the magnitude and location of strong cooling events associated with bora winds, intense dry winds from the northeast with strong spatial gradients resulting from orographic effects. Clearly, this directly reflects on the quality of resulting surface heat fluxes that are forcing the ocean surface and consequently on the resulting circulation induced.
We implemented the Regional Ocean Model System (ROMS) forced by atmospheric fields provided by the Limited Area Model-Italy (LAMI) model, and calculated the heat budget for the Northern Adriatic, i.e. a region of approx. 20000 km2 north of Senigallia-Susak transect. We found that the heat content of the region is nearly completely controlled by surface heat fluxes, with advective heat fluxes by ocean currents through the Senigallia-Susak section playing a minor role.
This suggested the possibility of assessing changes of heat content in the Northern Adriatic from satellte SST imagery and in situ CTD and ADCPs data, deployed in the region during fall 2002-winter 2003. Such a data-derived direct estimation of heat content, expressed as equivalent surface fluxes, is then compared to that obtained implementing ROMS using LAMI atmospheric values via bulk formulae, and that obtained forcing ROMS directly with LAMI turbulent fluxes (no modelled SST feedback).