Simple instrumentation for measuring temperature gradients at the sea-air interface, including the results of Winter 1964/65 measurements

Abstract

Very little information is available on the temperature differences in the first several centimetres of air above the sea surface and the first few centimetres of water below the sea surface. Data of this kind are important in helping to understand heat exchange between the sea and the atmosphere. They may also be a significant factor in the phenomena of sonar surface-reverberation. A series of measurements is now underway to determine the magnitude and fluctuations of these temperature gradients during hourly, daily and seasonal intervals. These are being made in the open sea off the Ligurian Coast of Italy at about 34 deg 54.7'N, 9 deg 45'E. The gradients are measured with respect to the actual undulating surface of the sea. The instrumentation being used is described. The measurements made during the winter of 1964-65 have revealed the following: (1) A mean, hourly average-air-gradient of +1.6 deg C/10 cm, with an rms fluctuation of 0.6 deg C/10 cm. (2) A mean, hourly average-water-gradient of +0.086 deg C/10 cm, with an rms fluctuation of 0.025 deg C/10 cm. (3) On the average, the temperature difference in the first 10 cm of air above the sea-air interface was 2/3 of the temperature difference in the first 4.5 m.