Supplementary material to 'A Machine Learning Method for Estimating Atmospheric Trace Gas Concentration Baselines' - Kirstin Gerrand; Elena Fillola; Alistair J. Manning; Jgor Arduini; Paul B. Krummel; Chris R. Lunder; Jens Mühle; Simon O'Doherty; Sunyoung Park; Ronald G. Prinn; Stefan Reimann; Dickon Young; et al. (2025)