Dr Sean Healy is a senior scientist in the ECMWF satellite section. He joined ECMWF in 2003 after 7 years at the Met Office. Dr Sean Healy has worked on the applications of GNSS-RO measurements since 1996, starting with the validation of GPS-MET measurements. He subsequently co-developed the first "1D-Var" retrieval codes for GNSS-RO measurements and performed information content studies. He then designed and implemented the GNSS-RO refractivity assimilation system used operationally at the Met Office until 2010, and the bending angle assimilation system used operationally at ECMWF. He has written a two-dimensional GNSS-RO bending angle operator, and has contributed to publications on NWP, climate monitoring and reanalysis applications of GNSS-RO. More recently, he co-authored a paper on the use of the Ensemble of Data Assimilations (EDA) approach to estimate the scaling of GNSS-RO impact with observation number.