Stratéole 2: Long Duration Measurements of Aerosol Profiles in the TTL using the Reeldown Aerosol, Clouds, Humidity, and Temperature Sensor (RACHuTS) and LASP Optical Particle Counter (LOPC)

Abstract:

Stratéole 2 is a multinational effort to study the Tropical Tropopause Layer (TTL) and the tropical lower stratosphere using long duration super pressure balloons. The major objectives of the campaign are to investigate large and small scale atmospheric dynamics in the TTL, stratospheric hydration processes, and vertical transport of TTL aerosol with quasi-Lagrangian measurements of temperature, water vapor, and aerosols, among others. A Reeldown Aerosol, Clouds, Humidity, and Temperature Sensor (RACHuTS) is under development at the Laboratory for Atmospheric and Space Physics (LASP) to obtain vertical profiles from the balloon flight level near the top of the TTL at 17.5 km to a distance of 2 km below the gondola. The profiling unit of RACHuTS contains a FLASH-B hygrometer, a TSEN high precision temperature and pressure sensor, and an 8-channel (0.3 - 5 μm) optical particle counter (OPC). The balloon gondola will also contain the newly developed LASP Optical Particle Counter (LOPC), which has the capability of measuring >32 diameter channels from 0.27 - 13 μm. The combination of the RACHuTS OPC and LOPC on the same platform is expected to provide thousands of in situ profile measurements of aerosol size distributions across the TTL. This unique capability will help understand the transport of tropospheric aerosol across the TTL and into the lower stratosphere. Additionally, the flight level measurements from the LOPC will provide many months of near continuous measurements of lower stratospheric aerosol size distributions around the entire tropical belt. The major Stratéole 2 field campaigns are scheduled for 2021 and 2023 with a smaller proof of concept campaign scheduled for December 2018. Each campaign will provide up to 3 months of continuous measurements, and will capture the stratospheric impact of any volcanic events that occur during the campaign time frame.