Rainbuoys - Acoustic Rain Gauges Why ARGs? To estimate rainfall and wind over large areas MOD is interested in the reverse problem – if it’s raining, what will it do to the ambient underwater noise? A hydrophone hangs under the buoy at a depth of up to 30m These buoys use a hydrophone and matched electronics package supplied by the Canadian company Metocean. We have added a data logger and satellite telemetry using Orbcomm Some of you will know that the rain buoy project has been around for a few years Why re-design the buoys?

Acoustic Rain Gauge Attempt to estimate rainfall and wind strength from sound spectrum 16 frequency bins from 500 Hz to 50 kHz Hydrophone hangs 30m under buoy Hydrophone and acoustic processing electronics from Metocean We added data logger and Orbcomm telemetry

Hydrophone A new buoy has been designed by Kev Saw and Ian Waddington Largely plastic Battery pack for 6 months deployment Designed and built in around 3 months in time for Canadian cruise

Mast Design The stainless steel mast holds the Orbcomm and GPS antennas, A flashing light Radar reflector

CFAV Quest (Canadian Forces Auxiliary Vessel) A tad smaller than the Darwin Built in 1969 but recently underwent a major refit 20 berths for scientists, mainly in 2 or 4 berth cabins Designed for quietness Has gas turbine on upper deck for extra quiet running Usually drifts during night

Passing traffic.. MacDonald Bridge Orbcomm worked fine in this position

Deployment Mooring was designed by Ian Waddington Deployment and recovery pretty straightforward Dan Hutt

ARG buoy Orbcomm 3 messages per hour 466 bytes total per hour Panasonic is active for approx. 20 min per hour This is programmed using KXB command If message buffer starts to get full, Panasonic is switched to continuous mode

Land Station Rain Gauge 12 months at SOC Sends 2 messages/hour 294 bytes total per hour Samples rain level and temperature every minute

Land Station Messages

Expanded View – 1 week

Message delays during October-November 02 Maximum delay was 25 hours. Caused by mail server failure at SOC Average delay – 1.22 hours Median delay – 0.25 hours Daily pattern probably caused by interference from Vodaphone paging system

Comparative costs Orbcomm Iridium Receiver + antenna €2000 Airtime €18 per month plus €1.6 per minute Receiver + antenna €1000 Airtime €65 per month flat rate (Same as Iridium with 1 minute per day)

TriAxys Buoy Dan Hutt

Dan Hutt