Publications de Urs Martin Germann

A Characterisation of Alpine Mesocyclone Occurrence

Alexis Berne, Marco Gabella, Monika Feldmann, Urs Martin Germann

This work presents a characterisation of mesocyclone occurrence and frequency in the Alpine region, as observed from the Swiss operational radar network; 5 years of radar data are processed with a thunderstorm detection and tracking algorithm and subsequen ...

2021

Learning about the vertical structure of radar reflectivity using hydrometeor classes and neural networks in the Swiss Alps

Alexis Berne, Floortje Elisabeth Maria Van den Heuvel, Marco Gabella, Urs Martin Germann

The use of radar for precipitation measurement in mountainous regions is complicated by many factors, especially beam shielding by terrain features, which, for example, reduces the visibility of the shallow precipitation systems during the cold season. Whe ...

2020

LMA observations of upward lightning flashes at the Santis Tower initiated by nearby lightning activity

Farhad Rachidi-Haeri, Marcos Rubinstein, Jacopo Grazioli, Mohammad Azadifar, Nikola Besic, Amirhossein Mostajabi, Antonio Sunjerga, Urs Martin Germann

We present in this paper lightning current measurements, LMA (Lightning Mapping Array) data and fast antenna electric fields associated with upward flashes observed at the Santis Tower during summer of 2017. The LMA network consists of six stations that we ...

Elsevier2020

Analysis of the lightning production of convective cells

Farhad Rachidi-Haeri, Marcos Rubinstein, Jacopo Grazioli, Mohammad Azadifar, Nikola Besic, Amirhossein Mostajabi, Antonio Sunjerga, Urs Martin Germann

This paper presents an analysis of the lightningproduction of convective cells. The cells were detected by the MeteoSwiss Thunderstorms Radar Tracking (TRT) algorithm in the course of a lightning measurement campaign thattook place in the summer of 2017 in ...

2019

Polarimetric radar characteristics of lightning initiation and propagating channels

Farhad Rachidi-Haeri, Marcos Rubinstein, Jacopo Grazioli, Mohammad Azadifar, Nikola Besic, Amirhossein Mostajabi, Antonio Sunjerga, Urs Martin Germann

In this paper we present an analysis of a large dataset of lightning and polarimetric weather radar data collected in the course of a lightning measurement campaign that took place in the summer of 2017 in the area surrounding Säntis, in the northeastern p ...

2019

Meteorological Aspects of Self-Initiated Upward Lightning at the Santis Tower (Switzerland)

Farhad Rachidi-Haeri, Marcos Rubinstein, Jacopo Grazioli, Mohammad Azadifar, Nikola Besic, Amirhossein Mostajabi, Antonio Sunjerga, Urs Martin Germann

Interest in exploring the meteorological conditions favoring upward lightning from tall man-made structures has grown in recent years, largely due to the worldwide expansion of wind energy. To this end, instrumented towers existing around the world are the ...

2019

Spatial variability in snow precipitation and accumulation in COSMO–WRF simulations and radar estimations over complex terrain

Michael Lehning, Alexis Berne, Varun Sharma, Franziska Gerber, Nikola Besic, Marco Gabella, Urs Martin Germann

Snow distribution in complex alpine terrain and its evolution in the future climate is important in a variety of applications including hydropower, avalanche forecasting and freshwater resources. However, it is still challenging to quantitatively forecast ...

2018

A severe hail storm in complex topography in Switzerland-Observations and processes

Nikola Besic, Urs Martin Germann

This paper studies a damaging hail storm that occurred on 6 June 2015 in the complex topography of Switzerland. The storm persisted for several hours and produced large hail resulting in significant damage. Storms of comparable severity occur on average on ...

ELSEVIER SCIENCE INC2018

Unraveling hydrometeor mixtures in polarimetric radar measurements

Alexis Berne, Christophe Praz, Josué Etienne Gehring, Jacopo Grazioli, Nikola Besic, Marco Gabella, Urs Martin Germann

Radar-based hydrometeor classification typically comes down to determining the dominant type of hydrometeor populating a given radar sampling volume. In this paper we address the subsequent problem of inferring the secondary hydrometeor types present in a ...

Copernicus GmbH2018

Characterisation of the melting layer variability in an Alpine valley based on polarimetric X-band radar scans

Alexis Berne, Floortje Elisabeth Maria Van den Heuvel, Marco Gabella, Urs Martin Germann

The melting layer designates the transition region from solid to liquid precipitation, and is a typical feature of the vertical structure of stratiform precipitation. As it is characterised by a well-known signature in polarimetric radar variables, it can ...

COPERNICUS GESELLSCHAFT MBH2018

Measurement of Precipitation in the Alps Using Dual-Polarization C-Band Ground-Based Radars, the GPM Spaceborne Ku-Band Radar, and Rain Gauges

Alexis Berne, Peter James Speirs, Marco Gabella, Urs Martin Germann

The complex problem of quantitative precipitation estimation in the Alpine region is tackled from four different points of view: (1) the modern MeteoSwiss network of automatic telemetered rain gauges (GAUGE); (2) the recently upgraded MeteoSwiss dual-polar ...

2017

A radar-based regional extreme rainfall analysis to derive the thresholds for a novel automatic alert system in Switzerland

Alexis Berne, Luca Panziera, Marco Gabella, Urs Martin Germann

This paper presents a regional extreme rainfall analysis based on 10 years of radar data for the 159 regions adopted for official natural hazard warnings in Switzerland. Moreover, a nowcasting tool aimed at issuing heavy precipitation regional alerts is in ...

Copernicus GmbH2016

Hydrometeor classification through statistical clustering of polarimetric radar measurements: a semi-supervised approach

Alexis Berne, Jacopo Grazioli, Nikola Besic, Marco Gabella, Urs Martin Germann

Polarimetric radar-based hydrometeor classification is the procedure of identifying different types of hydrometeors by exploiting polarimetric radar observations. The main drawback of the existing supervised classification methods, mostly based on fuzzy lo ...

Copernicus GmbH2016

Propagation of uncertainty from observing systems and NWP into hydrological models: COST-731 Working Group 2

Eric Martin, Urs Martin Germann

The COST-731 action is focused on uncertainty propagation in hydrometeorological forecasting chains. Goals and activities of the action Working Group 2 are presented. Five foci for discussion and research have been identified: (1) understand uncertainties, ...

2010