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Concept

Graupel

Related publications (19)

Impact of intercepted and sub-canopy snow microstructure on snowpack response to rain-on-snow events under a boreal canopy

Michael Lehning, Nander Wever, Daniel Nadeau, Adrien Michel

Rain-on-snow events can cause severe flooding in snow-dominated regions. These are expected to become more frequent in the future as climate change shifts the precipitation from snowfall to rainfall. However, little is known about how winter rainfall inter ...

2024

Highly Hygroscopic Aerosols Facilitate Summer and Early‐Autumn Cloud Formation at Extremely Low Concentrations Over the Central Arctic Ocean

Julia Schmale, Andrea Baccarini

Arctic clouds are sensitive to atmospheric particles since these are sometimes in such low concentrations that clouds cannot always form under supersaturated water vapor conditions. This is especially true in the late summer, when aerosol concentrations ar ...

2024

Snowfall microphysics: a dual-frequency and Doppler spectral radar perspective

Anne-Claire Marie Billault--Roux

Snowfall is an essential component of the hydrological cycle, as it is involved in most precipitation on Earth, either directly as snow falling to the ground or indirectly as rain melted from snow. At the same time, the ice phase of clouds and precipitatio ...

EPFL2023

Snow transport in extreme environments: from small to large scale modeling

Daniela Brito Melo

The cold regions on Earth, such as the polar and high mountain regions, are snow covered for at least a part of the year. These snow-covered surfaces are highly dynamic, particularly under the influence of strong winds. The aeolian or wind-driven transport ...

EPFL2023

Highly Active Ice‐Nucleating Particles at the Summer North Pole

Julia Schmale

The amount of ice versus supercooled water in clouds is important for their radiative properties and role in climate feedbacks. Hence, knowledge of the concentration of ice-nucleating particles (INPs) is needed. Generally, the concentrations of INPs are fo ...

2022

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

Alexis Berne, Etienne Gabriel Henri Vignon, Josué Etienne Gehring

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

Modeling snow saltation: the effect of grain size and interparticle cohesion

Varun Sharma, Michael Lehning, Francesco Comola, Armin Sigmund, Daniela Brito Melo

This dataset includes the parallel application and the main results supporting the research article "Modeling snow saltation: the effect of grain size and interparticle cohesion" published at the Journal of Geophysical Research: Atmospheres.The code is a f ...

2021

Three-dimensional and real-scale modeling of flow regimes in dense snow avalanches

Johan Alexandre Philippe Gaume, Betty Sovilla, Xingyue Li

Snow avalanches cause fatalities and economic loss worldwide and are one of the most dangerous gravitational hazards in mountainous regions. Various flow behaviors have been reported in snow avalanches, making them challenging to be thoroughly understood a ...

2021

Evidence of Strong Flux Underestimation by Bulk Parametrizations During Drifting and Blowing Snow

Michael Lehning, Wolf Hendrik Huwald, Varun Sharma, Jérôme François Sylvain Dujardin, Francesco Comola, Armin Sigmund, Daniela Brito Melo

The influence of drifting and blowing snow on surface mass and energy exchange is difficult to quantify due to limitations in both measurements and models, but is still potentially very important over large areas with seasonal or perennial snow cover. We p ...

2022

Unsupervised classification of snowflake images using a generative adversarial network and K-medoids classification

Alexis Berne, Jussi Sakari Leinonen

The increasing availability of sensors imaging cloud and precipitation particles, like the Multi-Angle Snowflake Camera (MASC), has resulted in datasets comprising millions of images of falling snowflakes. Automated classification is required for effective ...

2020

Implications of observation-enhanced energy-balance snowmelt simulations for runoff modeling of Alpine catchments

Alain Michel Prenleloup

Snow is an important component of the water balance of many mountain watersheds worldwide. In a warming climate, snowmelt modeling and consequent soil water input, is often challenged by complex conditions such as rain-on-snow situations. This is why detai ...

ELSEVIER SCI LTD2019

Analysis of the lightning production of convective cells

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

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

Variations in Snow Crystal Riming and ZDR: A Case Analysis

Alexis Berne, Christophe Praz

A case study in terms of variations in differential reflectivity Z(DR) observed at X band and snow crystal riming is presented for a light-snow event that occurred near Greeley, Colorado, on 26-27 November 2015. In the early portion of the event, Z(DR) val ...

2018

Fragmentation of wind-blown snow crystals

Michael Lehning, Johan Alexandre Philippe Gaume, Francesco Comola, Enrico Paterna

Understanding the dynamics driving the transformation of snowfall crystals into blowing snow particles is critical to correctly account for the energy and mass balances in polar and alpine regions. Here we propose a fragmentation theory of fractal snow cry ...

2017

Upscaling the evolution of snow microstructure : from 4D image analysis to rigorous models

Quirien Eibhilín Krol

Snow microstructure and its evolution play an important role for various applications of snow physics in cryospheric sciences. The main modes of microstructure evolution in snow are referred to as isothermal and temperature gradient metamorphism. The forme ...

EPFL2017

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 radar and in situ observations of riming and snowfall microphysics during CLACE 2014

Alexis Berne, Jacopo Grazioli, Luca Panziera

This study investigates the microphysics of winter alpine snowfall occurring in mixed-phase clouds in an inner-Alpine valley during January and February 2014. The available observations include high-resolution polarimetric radar and in situ measurements of ...

Copernicus Publications2015

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

Use of a multilayer snow model to assess grazing conditions for reindeer

Michael Lehning

High-density snow layers deteriorate grazing conditions for reindeer during winter. We compare two different methods for identifying past winters with difficult grazing conditions for reindeer in Kautokeino, northern Norway. A long-term climate analysis ba ...

Int Glaciol Soc2013