High Definition Sounding System (HDSS) for airborne atmospheric profiling in Tropical Cyclones (TCs) and severe weather

A promising new dropsonde atmospheric profiling system, referred to as the High Definition Sounding System (HDSS) manufactured by Yankee Environmental Systems (YES, Inc.), has recently been developed and undergone test deployments from the CIRPAS Twin Otter, NASA DC-8 and NASA WB-57 offshore from California between Monterey and San Francisco, over the northeast Pacific offshore from Baja California and over the western Gulf of Mexico off the south Texas coast, respectively. Designed for high-altitude, rapid-fire deployments from manned and unmanned aircraft, the HDSS uses an Automated Dropsonde Dispenser (ADD) to deploy the new eXpendable Digital Dropsonde (XDD). Manufactured without a parachute, the XDD is designed for two different fall rates: fast-fall (ballistic) mode (30 m/s) or slow-fall (spiral) mode (15 m/s).

For the Twin Otter deployments, multiple intercomparisons of 10 XDD's were obtained with 14 NCAR/Vaisala RD-94 dropsondes and multiple NDBC surface moored buoys during two flight days. Results show good comparison of mean pressure, temperature, humidity and wind vector parameter profiles and electronic noise probability distributions. XDDs also provide measurements of SST throughout the profile with those near the surface showing excellent agreement with NDBC buoy SSTs (within 0.1 C). For the DC-8 deployments, done from 42K ft, XDD sonde data reception over distances in excess of 150 km using the HDSS was demonstrated for 6 sonde deployments, with each XDD also observing SST during the profile descent, including observations near the surface at extreme range. Good agreement between these multiple mean profiles was observed along with reduced noise variance over that observed during the Twin Otter deployments. XDD sonde deployments from the WB-57 flying at 65 K ft over the western Gulf were compared with radiosonde releases at Brownsville and Corpus Christi with results once again showing good agreement as well as low random noise. Results from deployments in rain regions will also be discussed.