MINIATURIZED DATA LOGGERS FOR DEEP SEA SEDIMENT TEMPERATURE GRADIENT MEASUREMENTS

Abstract

A new probe for autonomous high precision temperature measurements in deep sea sediments has been developed by Fa. Antares and the University of Bremen and extensively tested during several expeditions. The miniaturized temperature data loggers (MTLs) were constructed to be extremely robust, small (16 cm long) and easy to operate in waterdepths up to 6000 m. The temperature range extends from -5 to +60°C with an absolute accuracy of +/-0.1 K. Higher absolute accuracy requires calibration with a high precision thermometer. The resolution of the A/D converter is 16 bit which leads to a temperature resolution of 0.001 K. The logging duration and sampling rate can be chosen independently. Up to 18 h of measurement are possible with the highest sample rate of 1 s. Data are stored in the non-volatile memory which holds up to 64#800 measurements. The probe is configured and data downloaded without opening the pressure case by using specialized software and interface hardware. The MTLs offer a wide variety of marine science applications wherever a high precision temperature measurement is of interest. Our main application is the investigation of temperature gradients in deep sea sediments where measurements of gradients over a large depth interval are required by fixing loggers on either different kinds of core barrels or on long lances. During four expeditions, we used the loggers to measure sediment temperature gradients in several geological settings. The design of the attachments to the different carriers was varied to optimize the results for different needs. These tests were highly successful and the data of high quality. Therefore the loggers can be recommended for regular use in marine applications.