Applications of FCI near-IR 0.91µm channel for detection of low-level humidity

Up until the introduction of Meteosat Third Generation FCI instrument, the concept of low-level moisture estimation using solely data from imagers on board GEO satellites was to a high degree limited to so-called split window difference, i.e. difference in the brightness temperatures (BT) between two IR channels in ‘atmospheric WV window’ spectral region. Perhaps the biggest down side of this approach is the fact that BT difference relies heavily on the vertical temperature profiles of the atmosphere (the temperature of moisture level), also few other factors like aerosol presence play role.

Introduction of water-vapour absorption channel in the near infra-red (NIR) spectral region avoids the dependency on any temperature profiles, plus it provides even higher spatial sampling on the full disc domain. Hence the novel NIR0.91 FCI channels is seen as one of the crucial tools for nowcasting of severe storms, i.e. assessment of pre-conditions and moisture feeding dynamics of convective systems. The concept of NIR low-level moisture estimate and recent findings through a proxy data will be discussed.

It is worth adding that this is the first time that NIR0.9 channel is introduced with one of the major meteorological GEO satellite imagers, globally. Hence the importance for early discussions on potential capabilities.