PLUSNet HU-MIT virtual Real-Time Experiment 1 (AREA-HOPS-ESSE)

Acoustic predictions and optimization of the AUV path along the 2D bearings were carried out by Ding Wang and Henrik Schmidt using RAM, with sound-speed field inputs from HOPS predictions.

First, bearing/path 4 is chosen because this is where the acoustic variability and uncertainties are predicted to be the largest, based on one source and signals at four receiver depths (see transmission loss curves) The upwelling front is predicted to be crossing this path along bearing 4 (start of -sustained- upwelling conditions) and the environmental uncertainties are largest there too. Note that sensitivity and uncertainty are different.

Second, a linear programming algorithm that Ding Wang (MIT) is developing was used to select the yoyo pattern along this path 4. The results of the optimization are shown by the path in blue. Note that it captures the thermocline variations and the corresponding acoustic effects.

One source at central PLUSNet location, 4 bearings, 10km range, overlaid on centerography Optimized path for MIT-AUV, based on linear programming and RAM-HOPS predictions. Optimized path for MIT-AUV, based on linear programming and RAM-HOPS predictions. [ZOOM]
Difference in transmission loss (TL) as a function of range, for a source of 400Hz at 10m depth and for four receivers at 37.5, 127.5, 210 and 300 m depth. TL was computed using RAMS. Two HOPS forecast realisations of the sound-speed section corresponding to bearing 4 [Morning and Afternoon] Zoom over 0-100m depths in two HOPS sections. Notice variations in thermocline properties (its slopes, advected plumes and eddies)