ASIMET Modules
close-up of ASIMET modules on tower of discus buoy
Close-up of ASIMET modules on tower of three-meter discus buoy.
VOS Columbus Florida
VOS Columbus Florida bow mast
Close-up of VOS Columbus Florida bow-mast with first-generation ASIMET modules installed.

The Air-Sea Interaction METeorology (ASIMET) System

Technical documentation relating to buoy-mounted and shipboard ASIMET sensors is available from the WHOI Design Group for Electronics (DGE) Web page.

The Air-Sea Interaction Meteorology (ASIMET) system is a suite of meteorological and sea surface sensors that are deployed with different housings and packaging depending on the application. ASIMET modules (one or more sensors plus front-end electronics) may be self-powered and self-logging, connected to a central power supply and logger, or both. Together, these modules measure Air temperature (AT), specific humidity (SH), sea surface temperature and conductivity (SST, SSC), wind speed and direction (WSPD, WDIR), barometric pressure (BP), shortwave radiation (SWR), longwave radiation (LWR), and precipitation (PRC). These variables are used to compute air-sea fluxes of heat, moisture and momentum using bulk aerodynamic formulas.

On buoys, modules are packaged in titanium cylinders that include provisions for batteries and internal logging. Buoy modules are typically deployed in pairs, with 6 meteorological module pairs mounted on the buoy tower and a pair of temperature-conductivity sensors attached to the bridle leg. A central logger records one minute data from all the modules on a common time base, and also creates hourly averaged data that are transmitted to shore via Argos satellite telemetry.

On ships, the same sensors and electronics are used for all of the variables except SST, but with different packaging. The wind module is in a titanium housing like that used on buoys, but without an internal compass. Sensors for RH, AT, SWR, LWR and PRC are packaged together in a splash-proof fiberglass box. The BP sensor is in a second fiberglass box that also houses the central logger. All of these sensors are mounted on the ship’s bow mast. Power comes from a battery canister at the base of the mast. SST is an inside-hull mounted sensor placed just below the waterline of the ship (with magnets) that uses the ships hull as an acoustic path for sending data to the bow mast (SSC is not measured). Data are recorded once per minute in the logger, and a subset is sent by radio to the bridge every 6 minutes. The NOAA SEAS (Shipboard Environmental (Data) Acquisition System) incorporates these data into automated hourly weather reports from the ship to the National Weather Service.
See instructions on reading internally-stored flash card data.

Last updated: March 5, 2008