Publications related to Tornado vortex signature

Wind Transport of Snow Impacts Ka- and Ku-band Radar Signatures on Arctic Sea Ice

Marc Schneebeli Zeugin, David Nicholas Wagner

Wind transport alters the snow topography and microstructure on sea ice through snow redistribution controlled by deposition and erosion. The impact of these processes on radar signatures is poorly understood. Here, we examine the effects of snow redistrib ...

2023

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

Identification of snowfall microphysical processes from Eulerian vertical gradients of polarimetric radar variables

Alexis Berne, Josué Etienne Gehring, Etienne Gabriel Henri Vignon, Noémie Planat

Polarimetric radar systems are commonly used to study the microphysics of precipitation. While they offer continuous measurements with a large spatial coverage, retrieving information about the microphysical processes that govern the evolution of snowfall ...

COPERNICUS GESELLSCHAFT MBH2021

Characteristics of different charge transfer modes in upward flashes inferred from simultaneously measured currents and fields

Marcos Rubinstein, Mohammad Azadifar, Farhad Rachidi-Haeri, Davide Pavanello, Lixia He, Qi Li

The authors present an analysis of different charge transfer modes during upward negative flashes. The analysis includes a total number of 94 pulses that occurred during two upward negative flashes recorded at the Säntis Tower. The pulses included 59 mixed ...

2020

Polarimetric radar characteristics of lightning initiation and propagating channels

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

Statistical analysis of the spatial and temporal variability of polarimetric weather radar signals in the Alps

Floortje Elisabeth Maria Van den Heuvel

The accurate estimation of precipitation quantities arriving at the ground in complex terrain such as the Alps is complicated by many factors. The orography interacts with atmospheric flow and thus influences the spatial and temporal distribution as well a ...

EPFL2019

Modeling of Different Charge Transfer Modes in Upward Flashes Constrained by Simultaneously Measured Currents and Fields

Mario Paolone, Marcos Rubinstein, Mohammad Azadifar, Farhad Rachidi-Haeri, Davide Pavanello, Lixia He, Qi Li

The purpose of the paper is to investigate charge transfer modes in upward lightning flashes by means of numerical simulation constrained by concurrent observations of electromagnetic fields and currents. In particular, we focus on different types of pulse ...

2018

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

From model to radar variables: a new forward polarimetric radar operator for COSMO

Alexis Berne, Daniel Wolfensberger

In this work, a new forward polarimetric radar operator for the COSMO numerical weather prediction (NWP) model is proposed. This operator is able to simulate measurements of radar reflectivity at horizontal polarization, differential reflectivity as well a ...

Copernicus GmbH2018

A polarimetric radar operator to evaluate precipitation from the COSMO atmospheric model

Daniel Wolfensberger

Weather radars provide real-time measurements of precipitation at a high temporal and spatial resolution and over a large domain. A drawback, however, it that these measurements are indirect and require careful interpretation to yield relevant information ...

EPFL2018

Retrieval of the raindrop size distribution from polarimetric radar data using double-moment normalisation

Alexis Berne, Timothy Hugh Raupach

A new technique for estimating the raindrop size distribution (DSD) from polarimetric radar data is proposed. Two statistical moments of the DSD are estimated from polarimetric variables, and the DSD is reconstructed using a double-moment normalisation. Th ...

Copernicus GmbH2017

Detection and characterization of the melting layer based on polarimetric radar scans

Alexis Berne, Daniel Wolfensberger, Danny Eddy Scipion Castillo

Stratiform rain situations are generally associated with the presence of a melting layer characterized by a strong signature in polarimetric radar variables. This layer is an important feature as it indicates the transition from solid to liquid precipitati ...

Wiley-Blackwell2016

Hydrometeor classification from polarimetric radar measurements: a clustering approach

Alexis Berne, Devis Tuia, Jacopo Grazioli

A data-driven approach to the classification of hydrometeors from measurements collected with polarimetric weather radars is proposed. In a first step, the optimal number of hydrometeor classes (nopt) that can be reliably identified from a large set of pol ...

Copernicus Gesellschaft Mbh2015

Polarimetric weather radar : from signal processing to microphysical retrievals

Jacopo Grazioli

Accurate modelling of liquid, solid and mixed-phase precipitation requires a thorough understanding of phenomena occurring at various spatial and temporal scales. At the smallest scales, precipitation microphysics defines all the processes occurring at the ...

EPFL2015

Accuracy of Phase-Based Algorithms for the Estimation of the Specific Differential Phase Shift Using Simulated Polarimetric Weather Radar Data

Alexis Berne, Jacopo Grazioli, Marc Schneebeli Zeugin

The specific differential phase shift on propagation K-dp is widely employed in the study of precipitation, although little is known about the effective accuracy of its estimates. The aim of this letter is to analyze the quality of K-dp estimates, using re ...

Ieee-Inst Electrical Electronics Engineers Inc2014

Improved Estimation of the Specific Differential Phase Shift Using a Compilation of Kalman Filter Ensembles

Alexis Berne, Jacopo Grazioli, Marc Schneebeli Zeugin

A new algorithm for the accurate estimation of the specific differential phase shift on propagation (K-dp) from noisy total differential phase shift (Psi(dp)) measurements is presented for data acquired with a polarimetric weather radar. The new approach, ...

Institute of Electrical and Electronics Engineers2014

Influence of the Subgrid Variability of the Raindrop Size Distribution on Radar Rainfall Estimators

Alexis Berne, Joël Jaffrain

This work aims at quantifying the variability of the parameters of the power laws used for rain-rate estimation from radar data, on the basis of raindrop size distribution measurements over a typical weather radar pixel. Power laws between the rain rate an ...

American Meteorological Society2012

High-resolution vertical profiles of polarimetric X-band weather radar observables during snowfall in the Swiss Alps

Michael Lehning, Alexis Berne, Marc Schneebeli Zeugin

An X-band polarimetric radar was deployed in the eastern Swiss Alps at an altitude of 2133 m. Radar measurements were complemented with several weather stations deployed in an altitude range from 1500 to 3100 m as well as with a fixed GPS ground station th ...

Amer Meteorological Soc2012

Quantification of the Small-Scale Spatial Structure of the Raindrop Size Distribution from a Network of Disdrometers

Alexis Berne, Joël Jaffrain

The spatial structure of the raindrop size distribution (DSD) conveys crucial information for reliable quantitative estimation of rainfall using remote sensing techniques. To investigate this question, a network of 16 optical disdrometers has been deployed ...

American Meteorological Society2012