Hurricane and Severe Storm Sentinel (HS3): Mission Summary and Initial Result

Abstract:

The HS3 objectives are:

• To obtain measurements in the hurricane environment in order to identify the role of key factors such as large-scale wind systems, Saharan air masses, African Easterly Waves and their embedded critical layers.

• To observe and understand the three-dimensional mesoscale and convective-scale internal structures of tropical disturbances and cyclones and their role in intensity change.

The mission objectives were addressed using two Global Hawk (GH) Unmanned Airborne Systems (UASs) with separate comprehensive environmental and over-storm payloads. The GH flight altitudes (>17 km) allow overflights of most convection and sampling of upper-tropospheric winds. Deployments from Goddard’s Wallops Flight Facility and ~26-hour flight durations provided coverage of the entire Atlantic Ocean basin, and on-station times up to 6-20 h depending on storm location. Deployments were in September of 2012 and late-August to late-September 2013-2014.

Measurements from the Environmental GH Payload

• Continuous sampling of temperature and relative humidity in the clear-air environment from the scanning High-resolution Interferometer Sounder (S-HIS).

• Full tropospheric wind, temperature, and humidity profiles from the Advanced Vertical Atmospheric Profiling System (AVAPS) dropsonde system, which is capable of releasing up to 89 dropsondes in a single flight.

• Aerosol and cloud layer vertical structure from the Cloud Physics Lidar (CPL).

Measurements from the Over-Storm GH Payload

• Three-dimensional wind and precipitation fields from the High-altitude Wind and Rain Airborne Profiler (HIWRAP) conically scanning Doppler radar.

• Surface winds and rainfall from the Hurricane Imaging Radiometer (HIRAD) multi-frequency interferometric radiometer.

• Temperature, water vapor, and liquid water profiles, rain rates, and vertical precipitation profiles from the High-Altitude MMIC Sounding Radiometer (HAMSR).

The talk will discuss the flights that were conducted and summarize early results related to:

• Nadine’s (2012) interaction with the Saharan Air Layer

• Outflow structure as revealed by dropsondes and CPL

• Environmental conditions in weakly developing and non-developing storms in 2013

• Initial results for 2014 cases