Corrections to Bottom Pressure Records for Dynamic Temperature Response

Abstract

Factory calibration of Digiquartz? transducers allows for static temperature corrections, assuming that the temperature changes slowly enough during deployment that the gauge is always in thermal equilibrium. Deep ocean bottom pressure recorders used by the NOAA/PMEL Tsunami Project are sometimes deployed in environments where assumptions of thermal equilibrium do not hold. In these cases the static temperature correction is not sufficient; pressure signals arise that are due purely to dynamic changes in the temperature of the gauge itself. Previous authors have determined the dynamic response of a transducer by subjecting it to known temperature-forcing functions in the laboratory and measuring the pressure response. The authors have developed a method of estimating the temperature response by relating the pressure signal to the time derivative of temperature. This relationship has been explored both with field and laboratory data. Once the parameters describing this relationship have been determined, pressure records can be corrected for dynamic temperature effects. For one particular deployment at the Loihi Seamount in Hawaii, pressure ?noise? in the 2?120-min period band has been reduced from 8 mb to less than 1 mb.