The Urban Climate Observatory (UCO) Berlin for integrative research on atmospheric processes in cities

The Urban Climate Observatory (UCO) Berlin, Germany, is an open and long-term infrastructure for integrative research on urban climate, hydro-meteorology, and air quality. Quality-controlled observations are carried out to study interactions between atmospheric processes and urban structures, as well as climate variability and climate change in urban environments. It enables multi-scale, three-dimensional atmospheric studies, integrating observational and numerical modelling methods. The UCO Berlin includes the following components:The Urban Climate Observation Network (UCON) Berlin provides long-term observations of atmospheric variables (e.g., air temperature, relative humidity, precipitation) in the urban canopy layer at various locations since the 1990s. Since 2015 freely-available data from private weather stations in Berlin and surroundings have systematically been collected via crowdsourcing.Two radiation- and energy-balance towers in distinctly-different urban settings measure four-component radiation fluxes, turbulent fluxes of sensible and latent heat, and carbon-dioxide fluxes using eddy covariance systems since 2014 and 2018. One tower is an associate site of the European research infrastructure Integrated Carbon Observation System (ICOS) and part of the national ICOS-D network (ID: DE-BeR). The seasonal development of the vegetation in the visible and near-infrared range is observed at both locations using PhenoCams (phenocam.nau.edu).Ground-based remote sensing is used to study the urban boundary layer and beyond since 2017. Two Doppler-wind lidar systems provide profiles of horizontal and vertical wind speed and direction, as well as information on atmospheric turbulence. Cloud height, cloud cover, and aerosol layers are recorded with ceilometers in an urban and a non-urban setting. A microwave radiometer provides vertical profiles of air temperature and absolute humidity. Finally, an X-band Doppler weather radar with dual polarization for precipitation research is in operation since autumn 2022.This contribution provides an overview of the UCO Berlin and uses selected findings to highlight benefits of the multi-scale observations for urban atmospheric research.