The Feedback_low simulations are part of the Stratospheric Aerosol Geoengineering Large Ensemble project (GLENS) (reference)
using the NCAR Community Earth System Model with the Whole Atmosphere Community Climate Model as its atmospheric component. The Feedback_low simulations are a 3-member ensemble of stratospheric sulfate aerosol geoengineering simulations between 2020-2099 that instead of injecting sulfur dioxide at about 5km altitude above the tropopause at 4 latitudes, as done in GLENS, it injects at 1km altitude above the tropopause at the same 4 latitudes in order to keep global mean surface temperatures and temperature gradients at 2010-2030 levels.