Pinzón's path plans for the first transoceanic glider Scarlet Knight RU-27 derived from ESEOO's regional ocean model forecasting data of an inertial oscillations field in the NE Atlantic

Abstract

Unmanned Underwater Vehicles (UUVs) are used in Oceanography due to their relative low cost and wide range of capabilities. Gliders, being UUVs change their buoyancy to dive and climb describing a vertical saw tooth route. It produces an effective but low horizontal speed. As result it makes them strongly sensitive to the ocean dynamic, and therefore might have to adapt the heading using confident 4D current data sets. In this paper, it is outlined the first transoceanic path planner software for glider piloting for named Pinzon in honor of the captain of La Pinta (1492-93) Martin Alonso Pinzon. Pinzon path planner was engineered to assist RU-27 Scarlet Knight navigation of the first transatlantic glider flight (221 days, 7409 km). She crossed an inertial oscillation during her last stint in the NE Atlantic domain (1st Nov- 4th Dec 2009). Pinzon path planner integrated a novel path planning algorithm called CTS-A* (Constant-Time Surfacing A*) that managed real time 3D current fields (1º/20) forecast (+3 days) provided by the ESEOAT regional ocean model in the North East Atlantic´s domain. Pinzon/ESEOAT planning outputs were validated with those provided by the RU27 ground true paths. He was programmed allowing any bearing angle and integrating each 8 hours (RU-27 surfacing period), the ground true given by the glider location each 8h/surfacing. Pinz´on managed continuous space and time domains with realistic and validated hourly forecasts (3-days) of different oceanographic variables provided by the Spanish ESEOO Regional Ocean Forecasting System (IBI Myocean). Results showed that hourly ESEOAT 3D (Myocean IBI) forecasts captured the high current variability (inertial oscillations) reported by RU-27 on the 14ºW to 12ºW arriving Spain. Pinz´on provided confident routes that were confirmed by the ground true paths reported by the glider before her recovering in the Spain´s ZEE (4th Dec 09)5. This combination of path planning tools has shown to be especially useful for future long range transoceanic glider missions (Challenger glider mission6).