Validation Activities for the Level 2 Geophysical Products of the EUMETSAT Polar System-Second Generation (EPS-SG) Visible/Infrared Imager (METimage)

摘要

The EPS-SG Visible/Infrared Imaging mission is dedicated to supporting the optical imagery user needs for Numerical Weather Prediction (NWP), Nowcasting (NWC) and climate in the 2020 onwards timeframe. The VII mission is fulfilled by the METimage instrument, to be embarked on the Metop-SG-A satellites. METimage will fly in the mid-morning orbit of the Joint Polar System, whilst the early-afternoon orbits are served by the JPSS (U.S. Joint Polar Satellite System) Visible Infrared Imager Radiometer Suite (VIIRS). METimage is a cross-purpose medium resolution, multi-spectral optical imager, measuring radiation emitted and reflected by the Earth from a low-altitude sun synchronous orbit with a minimum swath width of 2700 km. The top of the atmosphere outgoing radiance will be sampled every 500 m (at nadir) with measurements made in 20 spectral channels ranging from 443 nm in the visible up to 13.345 μm in the thermal infrared. The following METimage geophysical products will be generated and validated by EUMETSAT: ? Cloud mask ? Atmospheric motion vectors. ? Cloud top height, microphysics and volcanic ash. ? Cloud top pressure using the oxygen-A band. ? Total precipitable water vapour from METimage visible/near-infrared bands. ? Total precipitable water vapour from METimage thermal infra-red bands This paper focuses on the validation activities planned for the METimage geophysical products to ensure they meet user requirements for the lifetime of the mission. The validation of level 2 variables relies on the availability of simultaneous and independent data providing the same information on the same horizontal scale. Validation methods include inter-comparisons with other validated missions through simultaneous nadir overpasses (both low Earth orbit and geostationary), comparisons with ground based observations, and short term weather forecasts. The level 2 product performance will be validated with respect to user requirements for all geographic regions and seasonal v