Development of a new Lagrangian float for studying coastal marine ecosystems

This paper presents an overview and initial testing results for a shallow water Lagrangian float designed to operate in coastal settings. The presented effort addresses the two main characteristics of the shallow coastal environment that preclude the direct of use of many successfully deep water floats, namely the higher variation of water densities near the coast compared with the open ocean and the highly varied bathymetry. Our idea is to develop a high capacity dynamic auto-ballasting system that is able to compensate for the expected seawater density variation over a broad range of water temperatures and salinities while using measurements of both pressure and altitude above the bottom. The major components of the float consist of a Netburner micro processor, rechargeable lithium ion battery system, piston style volume changing mechanism, sensors for pressure and altitude, and a safely system for recovery and emergency conditions. Results are presented for field tests that verify the performance of the float for a variety of behaviors that are of general utility for both water tracking an profile sampling.