MTSAT FoR is within ±30° lat/lon of SSP. All metadata files of Aqua granules data are downloaded from NASA GES DISC to specify AIRS granules which cover the FoR. Granule data of AIRS L1b which satisfy the condition are downloaded from NASA GES DISC. MTSAT HRIT images closest in time to the centre of each AIRS data granule are selected.