Marlin-Yug

New version of Iridium SVP-BTC80 RTC/GPS has been deployed in the Black Sea

15.12.2009

Three Iridium SVP-BTC80 RTC/GPS drifters were tested in the Black Sea during August-November 2009. New version of drifters is the quasi-Lagrangian barometric buoy equipped with 80-m temperature-profiling chain and Iridium modem of satellite communication for near-real time data transfer. This experiment was provided to try the new version of temperature-profiling drifters as well as evaluate the way of 3D measurements by set of drifters of temperature profiles variability within active layer.

The Iridium SVP-BTC80 RTC/GPS temperature-profiling buoy has the following features:

The drifter is a quasi-Lagrangian buoy with Holey-Sock drogue to follow closely with velocity and direction of subsurface currents.
The buoy is equipped with digital temperature-profiling chain. The chain has 16 temperature sensors and depth sensor at the end of chain. Quantity and locations of temperature sensors can be varied according to request of customer.
The buoy includes the GPS receiver with fast reacquisition of a GPS signals to be in operation after long being submerged.
The buoy has the barometric pressure sensor, which provides accurate measurements of pressure, when any weather and wave conditions.
Inserted Real Time Clock (RTC) has the GPS synchronization for different application, for example, to get data samples at round hours, i.e. at XX:00, XX+1:00, etc.
Regular repetition period of samples is 60 minutes. If necessary, the period can be decreased down to 15 minutes without loss of data set continuity.
Time delay between measurement and moment, when data is delivered to a user, is no longer than 5 minutes. Usually, the delay is 2-3 minutes independently of buoy location in the Ocean.
If deflection of chain from vertical orientation takes place under influence of shift currents, the depth of each temperature sensor is calculated inside buoy and data of measurements are transmitted with pairs: Ti – Hi, where Ti is temperature measured and Hi is calculated depth of temperature sensor.
The theoretical lifetime of drifter is at the level of 10 months. This value was experimentally confirmed during evaluation of the buoy in Atlantic Ocean.

Range of Iridium SVP-BTC80 RTC/GPS applications:

Composite real-time monitoring of the Ocean active layer.
Investigation with high space-time resolution of thermodynamic activity within active layer, for example: variability of temperature vertical profiles in mixed layer, season thermocline, cold intermediate layer.
Synchronous temperature measurements by set of drifters to get 3D view of temperature profiles variability within active layer.
Study of daily, seasonal and interseasonal thermodynamical variability in active layer.
Investigation of thermal power accumulation and consumption within the active layer, when appearance, evolution and passing of hurricanes.
Evaluation of vertical and horizontal heat transfer within active layer.

Some preliminary results of deployment are shown below.

Near-inertial oscillations in the Black Sea, traceable by means of 3 buoys with 30-min GPS locations

Temperature profiles measured by buoy with 30-min samples

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