(1) Aerosol effects on convective storms in a warmer climate (2) Lagrangian analysis of two flavours of Central European heatwaves: formation under Omega blocking vs. initiation by subtropical ridges (3) Analysis and correction of MJO related errors in subseasonal ECMWF ensemble forecasts (4) High-Resolution Modeling of Outdoor Human Thermal Comfort in complex Urban Environments using a Multiscale Deep-Learning Approach
 

(1) tbd (2) Serial clustering of multiple impact-related hazards in Germany (3) tbd (4) tbd

 
 

At temperatures between -40°C and 0°C, clouds can be mixed phase, so called because they consist of a mixture of both liquid cloud droplets and ice crystals. This type of cloud is especially poorly represented in climate models. One of the reasons is that both hydrometeors are assumed to be homogeneously mixed in global models, but observations show that ice and liquid are heterogeneously mixed and exist in separate "pockets". This difference in the 3-dimensional spatial distribution of ice and liquid is important to assess and quantify precipitation, cloud processes, radiative properties, and consequently their impact on climate change. The present study aims to better characterize mixed phase clouds and especially the spatial distribution of the thermodynamic phase and understand how meteorology, air parcel transport and aerosols impact it.
 
We defined a parameter to describe the spatial distribution of liquid and ice phases within mixed-phase clouds from observations from the space-based lidar CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarisation). We spatially and temporally collocated the satellite measurements with reanalysis retrievals of aerosol concentration and meteorological parameters from ERA5 (European Centre for Medium-Range Weather Forecasts Reanalysis v5) and MERRA-2 (Modern-Era Retrospective analysis for Research and Applications, version 2) and then applied a multi-linear linear regression fit to quantify the influence of the external parameters on the spatial distribution of the cloud phase up to first order. A second part of the study focuses on ground-based measurements from the North Slope Alaska Station (NSA), where the transport of air parcels is analysed according to cloud type.
 
Focusing on the Arctic region, the results show that temperature is the most important parameter influencing the liquid-ice interface: for example, clouds with a temperature above 265 K have seven times more liquid-ice interfaces and are more homogeneously mixed than clouds with a temperature below 253 K. Black carbon concentration are also important parameters to describe the phase distribution. At NSA, clouds associated with higher transport may be more heterogeneously mixed. The results could be used to refine the parameterisation of clouds in models and their impact on climate change. 

(1) tbd (2) Innovative climate indices to support adaptation strategies at local level - a participatory approach (3) ICON simulations for Swabian MOSES (4) The TEAMx (Multi-scale transport and exchange processes in the atmosphere over mountains – programme and experiment) observational campaign

Since October 2023, a high-resolution urban climate analysis – based on the air flow model FITNAH-3D has been available for Heidelberg, which covers the city area with a spatial resolution of 5 x 5 m.  The results can be used to derive statements about the current microclimatic state and the expected change in the quality of living and local climate comfort for citizens and residents. 
The new screening tool (the so-called climate scanner) allows the display of microclimatic effects of individual measures (tree planting, green facades, etc.) or changes to the position of existing buildings "instantly" via a GIS-interface - without the need for high-performance computing. This enables a fact-based assessment of climate adaptation measures even before the planning process, which in turn prevents costly subsequent adjustments.
The tool is based on an artificial intelligence which is built on a neural network that combines the results of the Heidelberg urban climate analysis with a large number of different urban climate analyses in Germany.

(1) Physical constraints on the stratospheric injection of trace gases from wildfires (2) tbd (3) Assessing the Impacts of Hailstorms in a future climate - first results (4) tbd

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(1) tbd (2) Impacts of Hailstorms on agricultural products (3) tbd (4) tbd