FESSTVaL: connecting dense surface networks, supersites and citizen to catch atmospheric variability at kilo- and subkilo-meter scales

FESSTVaL, the Field Experiment on Submeso Spatio-temporal Variability in Lindenberg took place in summer 2021 in Germany. Initially proposed by modellers to peer into the lifecycle of convective cold pools, it led observationalists design new instruments and new retrieval algorithms to catch variability at kilometer scales. Those included self-designed autonomous cold pool loggers (APOLLOs), self-built weather stations (MESSIs) and novel gust wind retrievals. FESSTVaL connected cheap, numerous surface observations, with a network of 182 instruments deployed in a 15-km radius around Lindenberg, with expansive vertically profiling instruments, deployed at three supersites. To augment the spatial coverage of the surface network, FESSTVaL connected to citizen and involved them in the measurement process. With its focus on observing the summertime boundary layer and its variability at kilometer scale, FESSTVaL also bridged between the numerous past field campaigns on either micro- or meso-scale phenomena. Not to forget that FESSTVaL took place around the supersite of the German Weather Service and benefitted from the connection between basic research and operational application, both on the observational and modelling side. In this talk, I’ll show how FESSTVaL connected communities and, from a process point of view, scales and which results were achieved. In particular FESSTVaL provided for the first time unprecedented highly-resolved spatio-temporal cold-pool structures, both in the horizontal and in the vertical dimension, associated with overpassing convective systems. FESSTVaL also captured the effects of the atmosphere on cold pool characteristics as well as the effects of cold pools on land surface properties.