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Posted 1/28/2009 Printable Fact Sheet

Aerial Reconnaissance Weather Officer Computer

The ARWO software and communication lines have made tremendous advances in hurricane reconnaissance data collection aboard the Air Force Reserve's fleet of WC-130J aircraft.


The Weatherbird computer software enables the ARWO operator to monitor atmospheric conditions, both numerically and graphically, near the WC-130J and transmit this data to monitoring stations on the ground. Atmospheric and aircraft flight data are sampled six times per second at flight level and formulated into 10-second averaged data sets by a signal conditioner. The software then uses the 10-second data to compute numerous higher level meteorological parameters, such as pressure, altitude, temperature, and dew point, all of which can be displayed and stored. The 10-second data is averaged into 30-second averages, which are then formulated into data messages, called High Density Observations each containing 10 minutes worth of information. The HDOBS are automatically sent to the National Hurricane Center in Miama via satellite communications, where they are fed directly into the NHC computers and are instantly available to hurricane forecasters as analysis and forecasting tools.

Finally, the software serves as a storage and transmission facility for data messages. Vertical sounding messages (referred to as DROPs) are produced by AVAPS (see below for more information), while horizontal observations (referred to as RECCO) and Vortex Data Messages are produced by the Weatherbird software. RECCO messages contain both sensed and subjective data collected by the ARWO at flight level, while VDMs are hurricane eye reports of location and intensity. All messages can be retrieved, edited and restored by the ARWO and finally sent to the customer via the satellite communication system. Plain language "administrative" messages can also be sent via satellite communications, enabling direct and fast communication between the mission ARWO and forecasters at the National Hurricane Center.


Aircraft position and flight-level wind information is provided by the CNIU. The main CNIU component is a GPS navigation unit which can pinpoint a position accurately to within one mile after an average 10-hour hurricane reconnaissance mission. This position and wind data is also stored by each controller and is included in the HDOBS messages.

The mission Aerial Reconnaissance Weather Officer can manipulate the stored data in a variety of ways. It can be displayed in various digital formats or graphically depicted in time series or position plots. The speed and flexibility with which data can be viewed aid the ARWO's analysis and decisions, dramatically improving his ability to maintain control of the mission in the rapidly changing environment of a hurricane.


The SATCOM consists of an onboard transceiver and antenna, plus a reciprocating station located on the ground. There are currently two operational ground stations; one at the National Hurricane Center and the other at Keesler Air Force Base, Miss. Messages passed are automatically displayed on the respective receiving station's computer monitor. An acknowledgment of receipt of a message is automatic and is instantaneously relayed to the sending station by the receiving station. This enhances the book keeping process by the ARWO on the aircraft and ensures that none of the critical hurricane reconnaissance data is lost in space.


The Advanced Vertical Atmospheric Profiling System marks a tremendous advance in hurricane reconnaissance data collection aboard the Air Force Reserve's fleet of WC-130J aircraft. AVAPS is a self-contained atmospheric profiling system, installed in two standard 19-inch racks, that records current atmospheric conditions vertically below the WC-130J aircraft as a deployed sonde falls to the surface. AVAPS consists of expendable sondes, a Dropsonde Telemetry Chassis, high power computer, and a color monitor.


The GPS sonde is a lightweight instrument package that is launched from the WC-130J aircraft. As it descends from aircraft altitude (5,000 - 38,000 feet) to the surface, at about 2500 feet per minute, it measures and transmits current pressure, temperature, humidity, wind speed and direction, and GPS position information to AVAPS hardware in the aircraft every 0.05 seconds. The sonde also receives GPS navigation signals from at least four GPS satellites, and measures the Doppler shift of each signal. Up to four sondes can be deployed simultaneously. AVAPS receives this data, processes it, then displays the time from launch, raw weather data, number of GPS satellites being tracked, and geopotential altitude for each sonde deployed. The raw and processed data are also written to the computer's internal hard drive. After the drop has ended, the data files can be printed and data can be analyzed by the ASPEN program.


After drop termination, the Weather Loadmaster uses the ASPEN program to analyze and edit the collected weather data and formats the data to a standard code. The edited and formatted message is then ready for transmission to the ground station via SATCOM. ASPEN is a highly complex computer program that is used for the analysis, plotting, transmission, and quality control of AVAPS sounding data. Due to the very hectic and busy nature of the hurricane reconnaissance mission, ASPEN was specially designed to operate as automatically as possible, while allowing the user to have full control over the quality control methods. If at any time the processing needs to be modified, the user, who is a highly trained airborne meteorologists, can change the quality control parameters and reprocess the data as many times as necessary.

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