STFC RAL methane retrievals from IASI on board MetOp-B, version 2.0

This Infrared Atmospheric Sounding Interferometer (IASI) methane dataset contains height-resolved and column-averaged volume mixing ratios of atmospheric methane (CH4) retrieved from the IASI instrument on the MetOp-B satellite. It also includes column-averaged water vapour (H2O), a scale factor for the HDO (water vapour isotopologue) volume mixing ratio profile, surface temperature, effective cloud fraction, effective cloud-top pressure and scale factors for two systematic residual spectra which are jointly retrieved from the spectral range 1232.25-1290.00 cm-1. This dataset was produced by Version 2.0 of the Rutherford Appleton Laboratory's (RAL's) IASI optimal estimation scheme to retrieve methane, which takes as input temperature and water vapour profiles and surface spectral emissivity pre-retrieved by RAL's Infrared and Microwave Scheme applied to IASI, MHS and AMSU-A on MetOp-B. The dataset additionally contains selected a priori values and uncertainties adopted in the optimal estimation scheme and retrieval output diagnostics such as the retrieval cost and the averaging kernels. Development of the Version 2.0 scheme and its application to MetOp-A (2007-2017, http://dx.doi.org/10.5285/f717a8ea622f495397f4e76f777349d1) was funded by the National Centre for Earth Observation (NCEO) under the UK Natural Environment Research Council (NERC) with additional funding from EUMETSAT. Adaptation to MetOp-B and production of the IASI MetOp-B methane dataset 01/2018-03/2021 were funded by NCEO and ESA Contract No. 4000129987/20/I-DT Methane+. Data were produced by the United Kingdom Research and Innovation (UKRI) Science and Technology Facilities Council (STFC) Remote Sensing Group (RSG) at the Rutherford Appleton Laboratory (RAL).