urbisphere-Berlin Campaign: Investigating Multiscale Urban Impacts on the Atmospheric Boundary Layer
Daniel Fenner, Andreas Christen, Sue Grimmond, Fred Meier, William H. Morrison, Matthias Zeeman, Janet F. Barlow, Joern Birkmann, Lewis Blunn, Nektarios Chrysoulakis, Matthew Clements, Russell Glazer, Denise Hertwig, Simone Kotthaus, K. König, Dana Looschelders, Zina Mitraka, Dimitris Poursanidis, Dimitris Tsirantonakis, Benjamin Bechtel, Kit Benjamin, Frank Beyrich, Ferdinand Briegel, Gregor Feigel, Carlotta Gertsen, Nimra Iqbal, Jonas Kittner, Humphrey Lean, Yiqing Liu, Zhiwen Luo, Megan McGrory, Swen Metzger, Matthew Paskin, Marvin Ravan, Thomas Ruhtz, Bethany Saunders, Dieter Scherer, Stefán Thor Smith, Megan Stretton, Katja Trachte, Melania Van Hove
Abstract
Abstract For next-generation weather and climate numerical models to resolve cities, both higher spatial resolution and subgrid parameterizations of urban canopy–atmosphere processes are required. The key is to better understand intraurban variability and urban–rural differences in atmospheric boundary layer (ABL) dynamics. This includes upwind–downwind effects due to cities’ influences on the atmosphere beyond their boundaries. To address these aspects, a network of >25 ground-based remote sensing sites was designed for the Berlin region (Germany), considering city form, function, and typical weather conditions. This allows investigation of how different urban densities and human activities impact ABL dynamics. As part of the interdisciplinary European Research Council Grant urbisphere , the network was operated from autumn 2021 to autumn 2022. Here, we provide an overview of the scientific aims, campaign setup, and results from 2 days, highlighting multiscale urban impacts on the atmosphere in combination with high-resolution numerical modeling at 100-m grid spacing. During a spring day, the analyses show systematic upwind-city-downwind effects in ABL heights, largely driven by urban–rural differences in surface heat fluxes. During a heatwave day, ABL height is remarkably deep, yet spatial differences in ABL heights are less pronounced due to regionally dry soil conditions, resulting in similar observed surface heat fluxes. Our modeling results provide further insights into ABL characteristics not resolved by the observation network, highlighting synergies between both approaches. Our data and findings will support modeling to help deliver services to a wider community from citizens to those managing health, energy, transport, land use, and other city infrastructure and operations. Significance Statement A yearlong field campaign with a dense and systematic network of sites provides comprehensive measurements of the atmospheric boundary layer to gain deep knowledge of urban–rural and intraurban variability of surface–atmosphere exchanges. Understanding these is of high relevance for developing next-generation numerical weather prediction and climate models. We showcase the campaign and highlight synergies between ground-based and satellite observations and high-resolution numerical weather prediction modeling on two example days. Our findings show multiscale interactions between city and atmosphere, including urban-induced effects beyond the city’s boundaries (“urban plume”) and urban impacts under heatwave conditions. These results are important for developing dynamic modeling frameworks, which will help in delivering services to make cities more resilient.