Instrumentation Specifications

Meteorological Airborne Science INstrumentation (MASIN) equipment on the BAS Twin Otter VPF-AZ

Total Temperature	Goodrich Rosemount Probes mounted on the nose. A non de-iced model 102E4AL and a de-iced model 102AU1AG logged at 0.7Hz.
Altitude and Air Speed	Static and Dynamic pressure from the aircraft static ports and heated pitot tube, logged using Honeywell HPA sensors at 5Hz.
Cooled-Mirror Hygrometer	A Buck 1011C cooled mirror hygrometer is fitted. Chamber pressure and mirror temperature are recorded at 1Hz. A Rosemount mounted Vaisala Humicap sensor is also logged.
Radiometers	Eppley PIR and PSP sensors fitted to the roof and underside of the aircraft. Logged at around 10 Hz.
Infra-red Thermometer	Heimann model KT19.82 infra-red thermometer mounted in the floor hatch panel. There is a solenoid-operated, ambient temperature, black-body calibration target that can be brought into view during flight. Data are recorded at around 10Hz.
Laser Altimeter	A Riegl LD90-3800VHS-FLP Laser Altimeter is fitted in the floor hatch. Returns up to a few hundred metres are possible depending on the surface at repetition frequencies up to 2 kHz.
Cameras	Two Sony DV-tape cameras can be used. One downwards looking mounted in the camera hatch, one forward looking mounted in the cockpit. A Canon EOS7D with 15mm lens can be triggered to take 18MP images at up to 1 frame/sec.
Laser Scanner	A Riegl Q240 Laser scanner has been used for mapping sea ice.
Radar Altimeters	Data are recorded from the aircraft’s two radar altimeters at around 10Hz. These have a range of 1000m with a wider beam compared to the laser altimeter.
Turbulence Probe	A NOAA/ARA BAT ‘Best Aircraft Turbulence’ probe is fitted on a boom extending forward from the roof of the aircraft. This 9 hole probe records pressures and exposed thermocouple temperatures for measuring turbulence by eddy covariance in conjunction with attitude measurements. 3-axis accelerometer data are also recorded from the BAT Probe. Heaters are fitted inside the hemisphere to enable the instrument to be usable even after encountering icing.
GPS Position	Around 5m position accuracy recorded at 10Hz from the JAVAD 4-antenna GPS attitude system. For greater accuracy this is supplemented by a Trimble 5700 survey system using an antenna mounted above the laser altimeter and processed in kinematic mode with a second ground based unit.
GPS Attitude and Reference System	A JAVAD AT4 4-antenna GPS system records heading, pitch and roll at 20Hz and velocites at 10 Hz. Antennas are permanently fitted to each wingtip and fore and aft of the fuselage.
Inertial Attitude and Heading Systems	Aircraft attitudes and rate of change are recorded from the aircraft avionics Litef AHRS system. This is converted from ARINC format at 64Hz. There is also an OXTS Inertial+ GPS linked INU available which stores data internally.
Wing Hardpoints	Both wings have hardpoints, zivko carbon fibre pylons and cabling to accept PMS footprint instruments.
Cloud Probe	An under-wing pylon mounted Droplet Measurement Technologies CAPS Probe comprises of a 2D imaging probe(25µm–1550µm), aerosol spectrometer (0.5μm–50μm) and liquid water content probe (0.01–3.0g/m3). The probe has a dedicated logging PC and comprehensive instrument de-icing heaters.
Closed Path water vapour and CO2 sensor	A LICOR LI-7000 closed path infra-red gas analyser is fitted. Sampling is from a Rosemount inlet and readings are triggered at 50 Hz.
Aerosol Inlet	A Brectel Model 1200 Isokinetic Inlet is currently being fitted. >95% efficient for 0.01μm to 6μm.
Condensation Particle Counter	A TSI 3010 CPC can be rack fitted.
Aerosol Spectrometer	A Grimm model 1.109 portable aerosol spectrometer. 31 channels 0.25μm to 32μm.
Central Logging System	All instruments apart from the CAPS probe are logged to a single rack PC using Labview and associated National Instruments hardware including networked compact Fieldpoint modules in the roof and floor. The logging can be monitored and controlled from the main rack in the cabin as well as a remote touch screen in the co-pilot’s seat. CAPS has a dedicated computer. Dual KVM switches allow both the rear operators screen and the cockpit display to switch to either PC.