Variations in upper troposphere and lower stratosphere (UTLS) composition and temperature exert a pronounced impact on Earth’s overall radiative balance and, in turn, on surface climate and climate feedbacks. While satellite limb sounding instruments provide the best combination of vertical resolution and global coverage in the UTLS, their vertical resolution is too coarse to fully characterize the steep gradients present in the UTLS.
Here, we discuss measurements from the Airborne Scanning Microwave Limb Sounder (A-SMLS). A-SMLS was developed at NASA's Jet Propulsion Laboratory (JPL) under the NASA Instrument Incubator Program (IIP-2007 and IIP-2013) and updated under the Airborne Institute Technology Transition program (AITT-2019). A-SMLS builds on heritage from the Microwave Limb Sounder instruments on NASA's Upper Atmosphere Research Satellite (UARS, 1991--2000) and Aura (2004--) missions.
UTLS processes such as convective outflow, long-range pollution transport, troposphere-stratosphere exchange, volcanic plumes, and pyrocumulonimbus, strongly influence climate and air quality but remain incompletely understood. A-SMLS aims to shed light on these key UTLS processes through suborbital measurements onboard the ER-2 and WB-57 platforms, while further driving microwave limb sounder technology development.