Thermal sediment behaviour of Puerto Cuatreros tidal flats.

PICCOLO, M CINTIA; PERILLO, GERARDO M. E.; BEIGT, DÉBORA

Mar del Plata

Congreso; Joint IAPSO-IABO Assemblies, 2001: An Ocean Odyssey; 2001

IAPSO-IABO

The thermal features of the air (and water) over a tidal flat and within the sediments are described.Data were collected at Puerto Cuatreros (Bahía Blanca Estuary, Argentina) tidal flat during one year.Soil and water (or air) temperatures were measured continuously employing a thermistor chain thatincluded also a radiometer. Meteorological data was gathered from an automatic weather stationlocated at less than 5 km from the study site. The thermistors were located at 3 levels below thesediment surface (-0.05 m, -0.15 m, -0.25 m), at one level in the water column, and at one level in theair column (0.05 m). The measuring depth sand heights were selected to provide a detailedinformation of the temperature variations and gradients within and over the tidal flat, and also toanalyse the influence of flooding and exposition of the flats to the atmosphere. Temperature in theintertidal sediments exhibit rapid changes which occur principally during tidal inundation. Verticalgradients of 0.5 ºC/cm were found in the upper 0.25 m layer. Mean thermal diffusivity resulted equalto 0.40 10-6 m2 s-1. Spectral analysis of the sediment temperature time series show the importanceof synoptic, diurnal, semidiurnal and tidal time scale processes. Sediment temperature spectra showpeaks at 24 and 6 h, confirming that radiation and tides are the driving mechanisms of the thermalbehavior over and within the tidal flat.