The WCRP Core Project Stratosphere-troposphere Processes And their Role in Climate (SPARC) leadership is composed of experts from around the world who dedicate their time to SPARC's international activities. These include the SPARC Scientific Steering Group (SSG), who serve to guide SPARC's scientific focus. SPARC is now accepting nominations (or self-nominations) for SSG membership to serve from January 2019 - December 2021 (initial three-year term can be extended by two additional years). If you are interested please complete the online form here. The deadline for nominations is 30 September 2017.