A New Quasi-Horizontal Glider to Measure Biophysical Microstructure

Abstract

his study describes the development of a new tethered quasi-horizontal microstructure profiler: the Turbulence Ocean Microstructure Acquisition Profiler?Glider [TurboMAP-Glider (TMG)]. It is a unique instrument, capable of measuring ocean microstructure (temperature and turbulent velocity shear), chlorophyll, and turbidity simultaneously through a quasi-horizontal perspective. Three field experiments were carried out near Joga-shima, Japan, to test the TMG flight performance, and those results as well as comparisons with a laser-based vertical profiler, TurboMAP-L (TM), are described here. The TMG was capable of flying with an angle of attack of less than 25° and was reasonably stable for up to 300 m horizontally over 100-m depth. Some new and relevant empirical results about quasi-horizontal application of high-resolution chlorophyll-a fluorescence sensors are presented. The ratio between the Thorpe length scale and the Ozmidov length scale was used as a tracer to demonstrate that most of the TMG density inversions are due to horizontal variability and not to vertical overturning. These waveform structures are probably due to the horizontal inhomogeneity of the density field and are likely caused by internal waves.