Description =========== 1. convective activity ---------------------- I use at the moment the SEVIRI brightness temperature (BT) at 10.8 um which is, for opaque clouds, a good proxy for cloud-top temperature. Following Schroeder et al. (2009), I take a threshold of 230 K and call the frequency to fall below the threshold "convective activity". The threshold itself might be chosen differently. There is some variation in literature, e.g. Tobin et al. (2012) took 240 K for the definition of convective aggregation whereas Machado et al. (1998) as well as Machado and Laurent (2004) applied two different threshold of 245 and 235 K, respectively, to identify and track tropical convective of the Americas. 2. liquid-water cloud frequency ------------------------------- To get an impression about the representation of liquid-water clouds in the ICON simulations, especially concerning the Stratocumulus fields in the Southern subtropical Atlantic, I use again BT at 10.8 um and select the interval between 250 and 290 K. Ocean surfaces are typically warmer, land at night might be not. Hence, there is a change of misdetections over land at night. In addition, I set a threshold to two BT differences, the first is the difference between BTs measures or simulated at 10.8 and 12.0 um, the second the difference between 8.7 and 10.8. All three considered channels are in the atmospheric window which means that they are less affected by atmospheric absorption. For BT 10.8 - 12.0, I take a upper threshold of 1 K. Clearsky is typically larger due to the slightly higher and that's why colder emission height of the 12.0 um channel. For BT 8.7 - 10.8, I set an upper threshold of 0 K. Ice cloud tend to have more positive values and liquid-water clouds more negative due to spectral differences in scattering and absorption properties. I not sure if this introduced threshold scheme fits to the standard cloud classification methods... 3. water-vapor related activity ------------------------------- These fields are constructed from the 6.3 um SEVIRI channel. This channel is heavily affected by water vapor absorption and peaks in the upper troposphere. As consequence, only high clouds appear in the BT6.2. In the current version, I applied lower and upper thresholds of 235 and 245 K to highlight (i) high cloud-affected or moist region or (ii) dry patches which are especially good to visualize the propagation of equatorial waves. References ------------ Machado, L., Rossow, W., Guedes, R. and Walker, A., (1998): Life cycle variations of mesoscale convective systems over the Americas. Mon. Wea. Rev., {126}, p. {1630-1654}. Machado, L. A. T. and Laurent, H., (2004): The Convective System Area Expansion over Amazonia and Its Relationships with Convective System Life Duration and High-Level Wind Divergence. Mon. Wea. Rev., 132, p. 714-725. Schroeder, M., Koenig, M. and Schmetz, J., (2009): Deep convection observed by the Spinning Enhanced Visible and Infrared Imager on board Meteosat 8: Spatial distribution and temporal evolution over Africa in summer and winter 2006. J. Geophys. Res., {114}, p. D05109. Tobin, I., Bony, S. and Roca, R., (2012): Observational Evidence for Relationships between the Degree of Aggregation of Deep Convection, Water Vapor, Surface Fluxes, and Radiation. J. Climate, American Meteorological Society, 25, p. 6885–6904.