Thermal sediment behaviour of Puerto Cuatreros tidal flats

PICCOLO, M.C.; PERILLO, G.M.E.; BEIGT, D.

Mar del Plata

Congreso; 2001. IAPSO -IABO Meeting. The 2001 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 that included also a radiometer. Meteorological data was gathered from an automatic weather station located at less than 5 km from the study site. The thermistors were located at 3 levels below the sediment surface (-0.05 m, -0.15 m, -0.25 m), at one level in the water column, and at one level in the air column (0.05 m). The measuring depth sand heights were selected to provide a detailed information of the temperature variations and gradients within and over the tidal flat, and also to analyse the influence of flooding and exposition of the flats to the atmosphere. Temperature in the intertidal sediments exhibit rapid changes which occur principally during tidal inundation. Vertical gradients of 0.5 ºC/cm were found in the upper 0.25 m layer. Mean thermal diffusivity resulted equal to 0.40 10-6 m2 s-1. Spectral analysis of the sediment temperature time series show the importance of synoptic, diurnal, semidiurnal and tidal time scale processes. Sediment temperature spectra show peaks at 24 and 6 h, confirming that radiation and tides are the driving mechanisms of the thermal behavior over and within the tidal flat.