PD Dr. Silke Trömel

δ is a still underutilized polarimetric variable, which should not be ignored in rainfall retrievals based on specific differential phase KDP and bears valuable microphysical information.

For each overpass of GPM on the region detected by the Bonner radar, two and three dimensional data is created. This provides information about the current precipitation. To compare the GPM and BoXPol data, the polar data of the Bonn radar have to be interpolated on the GPM grid.

Lifecycle analysis of severe convective storms provide a deeper understanding of precipitation processes which can be exploited for nowcasting and model parameterizations.

It is extremely important to know the precise location of rain/snow boundary at the surface and its progression in time, and also to know if, where and when rain changes to freezing rain or ice pellets or other precipitation types.

Object-based analyses of intense hail storms are performed and a hail size discrimination algorithm will be developed in order to distinguish between harmless and threatening hail sizes.

The twin research X-band polarimetric Doppler radars in Bonn (BoXPol) and Jülich (JuXPol, in approx. 50km distance) and overlapping C-band radars of the German Weather Service are exploited to generate local 3D polarimetric composites. A 2D local BoXPol-JuXPol composite is generated operationally (Composite)

The fully equipped storm chaser bus for operation within the common Bonn/Cologne laboratory class and for research experiments includes a trailer equipped with a MicroRainRadar (MRR) and a ceilometer mounted on a steerable platform, a disdrometer, a fish-eye all-sky camera, and standard meteorological instruments (ventilated psychrometer, wind) installed on a telescopic rod, and a pressure sensor.

The twin X-band radar system of Bonn and Jülich is used to develop an empirical approach to quantify the uncertainties of radar based precipitation estimation. The use of two identical radars with a large overlapping area makes it possible to directly compare separate radar measurements in almost the same point in space and time.

Wradlib is an Open Source Library for Weather Radar Data Processing (wradlib). The radar group uses and also extends the library (Kai Mühlbauer, see below)

Convective organizations can be observed on a range of scales from the smaller to the larger ones. The extend to which these organizations are important for climate remains, however, poorly understood. Particularly on the meso or sub-synoptic scales since global models used for climate studies do not include representation of subgrid-scale organization.

To derive reliable relations between reflectivity Z and ice water content IWC is a challenging task, because they strongly depend on the snow habit. Thus, classification and quantification of ice above the freezing level is a new upcoming research topic within the research group.

Multi-sensor observations of anvil mammatus are analyzed in order to gain a more detailed understanding of their spatio-temporal structure and microphysical characterization.

Polarimetric radar measurements enable us to evaluate the representation of cloud and precipitation systems in the respective model and create an observational basis for model improvement.

Rainfall retrievals based on specific attenuation R(A) are less sensitive to variations in drop-size distribution, and unaffected by reflectivity biases due to miscalibration, partial beam blockage, and wet radomes.

The raw moment data is transferred in near-real-time to dedicated processing machines, which perform e.g. preprocessing, filtering, compositing, quantitative precipitation estimation QPE, and visualization on the institute's web-page (Archives).

The variability in raindrop size distributions and attenuation effects are the two major sources of uncertainty in radar-based quantitative precipitation estimation (QPE) even when dual-polarization radars are used. New methods are introduced to exploit the measurements by commercial microwave radio links to reduce the uncertainties in both attenuation correction and rainfall estimation.

Algorithms in use to detect and eliminate backscatter differential phase δ are currently investigated to eliminate inhomogeneities in radar data generated by windmills.