Do optically denser trade-wind cumuli live longer?

We present a detailed investigation of the lifetime of Caribbean trade-wind cumulus clouds and the temporal evolution of their physical properties based on geostationary observations with the Advanced Baseline Imager (Schmit et al., 2017) aboard the GOES-16 satellite during the “ElUcidating the RolE of Cloud-Circulation Coupling in ClimAte” (EUREC⁴A; Stevens et al., 2021) field experiment in winter 2020. A first application of our upgraded cloud-tracking methodology (Seelig et al., 2021) to measurements with a spatio-temporal resolution of 2 × 2 km² and 1 min, respectively, enables the investigation of processes that control the lifetime of shallow marine cumulus clouds. Our analysis reveals that shallow marine cumulus clouds live longer when they span over a surface area that exceeds an order of tens of square kilometers. While these clouds show similar median cloud droplet size and number concentration compared to shorter-lived clouds, they contain more liquid water and, thus, show a cloud optical depth that is increased by about one third. Besides the effect of cloud optical depth, we find that the scale of the atmospheric motions with which the clouds interact is also critical to their lifetime.References:Schmit, T. J., Griffith, P., Gunshor, M. M., Daniels, J. M., Goodman, S. J., and Lebair, W. J.: A Closer Look at the ABI on the GOES-R Series, B. Am. Meteorol. Soc., 98, 681-698, https://doi.org/10.1175/BAMS-D-15-00230.1, 2017.Stevens, et al.: EUREC4A, Earth Syst. Sci. Data, 13, 4067-4119, https://doi.org/10.5194/essd-13-4067-2021, 2021.Seelig, T., Deneke, H., Quaas, J., and Tesche, M.: Life cycle of shallow marine cumulus clouds from geostationary satellite observations, J. Geophys. Res.: Atmos., 126(22), e2021JD035577, https://doi.org/10.1029/2021JD035577, 2021.