Building an Advanced Urban Model to learn about heat island effects and
derive mitigation strategies
Providing a climate data web portal with historical local weather
Climate change has changed the scope for Weather Services around the world. For a long time, it was about the precision of the weather forecast itself only - which had to remain very general most
of the time with one temperature covering a whole big city. The facts have been known all the time that there are big temperature differences between downtown and peripheral suburban areas. In a
pre climate crisis period, this didn't matter too much except in very rare record cases: If a nightly minimum was 21 degrees in the city itself and 15 in the outskirts, no direct danger for human
health was to be considered.
In the present and future environment these differences do and will matter - not only for meteorological reasons, but also environmentally. That is because of local differences in the amount of
pollution which is also gradually changing away from known patterns. Particulate matter from traffic slowly becomes less relevant in city centers, at the same time the promotion of wood stoves in
many countries overcompensates this improvement and deteriorates air quality from the urban periphery.
These areas of increased pollution will be transported across the city and a thorough knowledge of small scale air currents then becomes especially necessary not only to forecast but also to
alert people in a hotter and dirtier environment. Particulate matter in the winter and ozone in the summer will be the leading polluters of the future.
Meteologix and the Kachelmann GmbH are determined to help authorities with all challenges which may arise in the future: Knowing, where not to build in order not to block fresh air
corridors. Knowing, where life will only be sustainable by adding climate neutral A/C to existing buildings in high temperature areas and many more use cases.
We are grateful that the EU is funding the project "Next Generation City Climate Services Using Advanced Weather Models and Emerging Data Sources", or CityCLIM for short, as part of its Horizon
program. The aim of the project is to develop a cloud-based platform that provides various weather and climate services specifically for metropolitan areas based on data from weather models,
Earth observation and ground measurements. The project is being realised by a consortium of companies in collaboration with scientific working
groups and four European pilot cities.
Meteologix is proud to be part of the consortium and will develop a 100x100 m resolution model ("UltraHD") and a Climate Web Portal among other goals in the project.
task leader of the Advanced Urban Weather Model Dr. Stefan Horn:
"The UltraHD is the final link in a model chain, designed to provide operational weather forecasts at an unprecedented resolution. The model chain is driven by the best global forecast systems
available, enriched with the 1km Swiss SuperHD model to already provide one of the best high resolution forecasts available on the market. This chain is now extended with the UltraHD model to
gain insight into mixing and transport processes on the urban scale.
As a so called large eddy simulation model (LES) the UltraHD is capable of resolving turbulent motions in the planetary boundary layer. These motions, driven by surface friction, moisture and
heat fluxes in interaction with the surrounding weather situation play an important role in the distribution of heat, moisture and pollutants. Operational weather forecasts using a fully
compressible fluid dynamic model on this scale are computationally very demanding and are up to now avoided, using statistical downscaling approaches instead. Urban areas develop their own air
flow in certain situations, creating non-linear feedbacks on turbulent and laminar structures which is likely not covered adequately by statistical downscaling.
That is why the UltraHD model was designed to utilize the extensive power of latest acceleration hardware (GPUs) to provide fully featured meteorological simulations on very high resolution at
reasonable costs. Beside the turbulent motions, phase transitions of water, like evaporation, condensation and freezing processes, play a crucial role in boundary layer dynamics and the surface
energy budget. Those processes are represented using a state of the art two moment microphysical scheme. With that the UltraHD model will provide details in clouds and radiation. Addressing
another important question of urban health and risk management, the model also contains a suite of prognostic equations capable to reflect pollution and atmospheric chemistry processes in the
Meteologix, it's the third H2020 project after Automat and Cross-CPP. Project coordinator of Meteolologix’ contribution to CityCLIM Miriam Kachelmann:
“This project comprises a strong consortium with a tremendous amount of
expertise and experience in the field. Together with the OHB group, we will be able to connect and bundle already existing data from space and air in a generic climate platform that will make
this data easier accessible for further exploitation and usage. We will involve citizen directly into the discussion and process of scientific data collection together with the partners from the
Helmholtz institute (UFZ) and the 4 pilot city partners (RTL Luxembourg, Region of Central Macedonia, Valencia and Karlsruhe). Our long-term partners from ATB provide excellent expertise in
conceptualisation and implementation of the envisioned services and have a vast experience in the support of project coordination, which is lead by OHB Systems. The University of Valencia will
support the OHB group in processing the air- and space-borne data with their extensive skill set in data calibration and validation, urban thermal field variation mapping algorithm development
for SUHI analysis.
Thus, Meteologix AG (and the Kachelmann GmbH) are proud partners of this
innovative consortium and are looking forward to work on these important objectives to mitigate the effects of climate change.”
CityCLIM already started on 1 October 2021 and will now be implemented over a period of 36 months in total.