Development and Testing of the AXBT Realtime Editing System (ARES)

Casey Densmore, WHOI, Department of Physical Oceanography, Woods Hole, United States, Elizabeth Sanabia, US Naval Academy, Department of Oceanography, Annapolis, MD, United States and Steven R Jayne, WHOI, Department of Physical Oceanography, Woods Hole, MA, United States
The AXBT Realtime Editing System (ARES) was developed as a standalone system to process and quality control temperature-depth profiles from Airborne eXpendable BathyThermographs (AXBTs). Using ARES, AXBT data transmitted to the aircraft via VHF are first demodulated and digitized using a software-defined radio receiver, and then passed directly to the computer, bypassing any additional external hardware (e.g. audio recorders or proprietary receivers). The ARES software runs a fast Fourier transform to determine peak frequency and converts the frequency-time series to a temperature-depth profile using predefined fall-rate and temperature-frequency equations. Once data collection is completed, the raw temperature-depth profile is passed through a series of automated quality control algorithms designed to remove most of the subjective decision-making required by users in manual AXBT profile revision systems such as SASEA. These algorithms remove spikes, detect bottom strikes and erroneous features caused by VHF interference or faulty probes, and compare the temperature-depth profile to climatology, before displaying the profile to the user for additional manual editing. The profile quality control system was evaluated with over 1,000 previously collected AXBT profiles and had a 97% automation success rate, resulting in a 5% increase in the number of profiles of sufficient quality to be transmitted to the Global Telecommunication System. Additionally, the system was tested while collecting data from AXBTs deployed onboard USAF 53rd Weather Reconnaissance Squadron (“Hurricane Hunter”) missions into category-5 Hurricane Dorian (2019) in parallel with a pre-existing AXBT processing system, and the success of this operational test was evaluated.