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NCAR GPS dropsonde
Operational For Field Campaigns
Available for field campaigns. NCAR has one AVAPS system, which can be used in NCAR’s C-130 or G-V, or by the scientific community in other aircraft, such as the NASA DC-8. Request procedure is available to logged-in users only. Please create an account (if you don’t have one) and log in to see this information. Web site : http://www.eol.ucar.edu/instrumentation/sounding/dropsonde
Airborne Measurements
The NCAR GPS Dropsonde system has dramatically extended the envelope of atmospheric profiling capabilities. The GPS Dropsonde system has enabled a new mode of observations to support numerical weather prediction by providing data where it is most needed over areas where data is either non-existent or at a minimum (e.g. oceans, Polar areas, or data sparse land areas).The GPS Dropsonde system is NCAR/EOL’s Advanced Vertical Atmospheric Profiling System (AVAPS).
Dr. Steve Cohn – Facility Manager
In-Situ Sensing Facility, Earth Observing Laboratory/NCAR
Foothills Laboratory 3450 Mitchell Lane Boulder, CO 80301
Terry Hock
Earth Observing Laboratory 3450 Mitchell Lane Boulder, Colorado 80301
303 497 8767
DimensionsGPS dropsonde size : 2.75 inches (6.98 cm) diameter by 16 inches (40.6 cm) long.
WeightGPS dropsonde weight : <400 gms
Power Source Type9 volt Lithium battery pack (3 – cells)
Inlet AperturesDifferential pressure or spring loaded launch tube penetration of lower portion of aircraft
Heating/Cooling RequirementsNone
Airspeed/Altitude Requirements1) Global operation, at altitudes up to 24 km., 2) Deployment of dropsondes at indicated airspeeds up to 250 kts.
Operators RequiredOne
Ground RequirementsNo special requirements.
Suitable PlatformsNOAA : G-IV, P-3’s DLR : Falcon research aircraft USAF Reserve Hurricane Hunters : WC-130H & WC-130J AES Canada : Convair 580 research aircraft UK Met Office : C-130 NCAR : G-V & C-130
Data System1) The aircraft data system can receive and process data from four GPS dropsondes simultaneously. 2) Simple Graphical User Interface (GUI). 3) Continuously output real-time PTH and wind for each channel to the aircraft computer systems as the dropsondes are descending. 4) Operation on aircraft with or without aircraft data system. 5) The most significant feature of the AVAPS data system is its ability to receive and process data from up to 4 dropsondes simultaneously, which is essential for obtaining a fine horizontal distribution of soundings. Launch procedures are simple enough to allow releases less than 20 seconds apart. 6) The aircraft hardware is typically composed of a Personal Computer, color monitor, telemetry chassis and printer. The hardware is designed for installation into a standard 19-inch rack. The system also requires a GPS antenna mounted on the top of the aircraft and a UHF antenna, for receiving the dropsonde signal, mounted on the bottom of the aircraft. If available, an RS232 connection to the main aircraft data system for flight level information is highly desirable.
Measured ParameterPTH, wind
Measurement TechniqueAfter launch, the software processes PTH and GPS data from up to four dropsondes via the Dropsonde Telemetry Chassis and 16-port I/O panel. Both PTH and wind data are available every 0.5 s, although because they are obtained from independent modules, the
Operational Mode
Time Resolution0.5s
Horizontal ResolutionWith the 4 channel data system up to 4 dropsondes can be released at a 20 second interval, the horizontal resolution depends on the aircraft speed.
Other Resolution0.5 second sample rate from the falling dropsonde for wind and thermodynamic data.
PrecisionRange & Pressure: 1080-100 hPa, Range & Temperature: -90 to +60 C, Range & Humidity: 0-100%, Range & Horizontal Wind: 0-200 m/s, Resolution & Pressure: 0.1 hPa, Resolution & Temperature: 0.1 C, Resolution & Humidity: 1.0%, Resolution & Horizontal Wind: 0.
AccuracyAccuracy & Pressure: ± 1.0 hPa, Accuracy & Temperature: ± 0.2 C, Accuracy & Humidity: ± 5%, Accuracy & Horizonal Wind: ± 0.5 m/s
RangeThe GPS dropsonde can operate out to a telemetry range of 325 km.
Calibration MethodThe GPS dropsondes are calibrated at the factory.
LimitationsThe four channel data system limits the number of dropsondes in the air to four.at one
Hock, T. F., and J. L. Franklin, 1999: The NCAR GPS dropwindsonde. Bull. Amer. Meteor. Soc., 80, 407-420.
NCAR/EOL provides the operator for the AVAPS system.
8 Sep 2009 10:03