Collaborative Research: General Purpose Tool for Acoustic Remote Sensing and Mapping of Hydrothermal Flow

Rutgers University New Brunswick, New Brunswick NJ

Investigators

Abstract

Proposal - 0136768 0136644 The goal of this proposal is to develop and fabricate an acoustic remote sensing and mapping tool dedicated to studying hydrothermal flow at the seafloor. The new system will be deployable on a variety of ROVs, deep towed platforms, and stationary seafloor observatory networks for the study and detection of high and low temperature hydrothermal flow regimes. The sensor will implement two new acoustic methods that will enable detection and quantitative mapping of diffuse hydrothermal flow at the seafloor using acoustic scintillation thermography (AST) and volumetric studies of plume particle distributions and flow above the seafloor. These methods have been demonstrated using a commercial sonar system mounted on the ROV Jason during three previous experiments. The proposed sensor will improve upon the operational and technical limitations of the commercial system and enable long time scale experiments and larger-scale surveys using a variety of platforms. In addition, the sensor proposed will enable high quality scientific data collection and analysis thus providing a flexible test bed for new acoustic methods and applications of remote sensing to hydrothermal flow. The system will be compatible with available and proposed seafloor observatories, enabling interactive operation via the Internet. This proposal is the product of an ongoing collaboration between groups at Rutgers (Rona et al.) and the Applied Physics Laboratory of the University of Washington (APL-UW, Jones et al.) and arises from our experience in using commercial sonars for hydrothermal observations. The proposed instrumentation development is central to the goal of the PIs to observe focused and diffuse hydrothermal flow over long time periods. Design, fabrication, and local testing will be the responsibility of APL-UW whereas, the Rutgers group will contribute to the process of developing system specifications from scientific measurement requirements and will conduct the field tests, including analysis of test data. The new remote sensing tool will enable measurements of plume flow variability at long time scales (of order 1 year). Such scales are important in studies on the response of hydrothermal flow regimes to tidal forcing as well as to volcanic and tectonic events. The sensor will enable the implementation of new acoustic detection and mapping techniques for characterizing diffuse flow over large regions (10s of km2) of interest. It is proposed that this instrument will also enable studies of net heat flux from hydrothermal systems and its relation to geophysical, oceanographic, and biological processes.