Publications associées à Masse d'air

Turbulence in the Strongly Heterogeneous Near-Surface Boundary Layer over Patchy Snow

Michael Lehning, Dylan Stewart Reynolds, Michael Haugeneder

The near-surface boundary layer above patchy snow cover in mountainous terrain is characterized by a highly complex interplay of various flows on multiple scales. In this study, we present data from a comprehensive field campaign that cover a period of 21 ...

2024

Brown carbon absorption in the Mediterranean basin from local and long-range transported biomass burning air masses

Athanasios Nenes

This study examines the impact of light absorption from biomass burning (BB) brown carbon (BrC) in the Mediterranean basin from local and distant fire incidents during a typical fire season in August 2019 and under severe fire activity in August 2021. The ...

Elsevier2023

A Case Study on Drivers of the Isotopic Composition of Water Vapor at the Coast of East Antarctica

Michael Lehning, Armin Sigmund, Riqo Chaar

Stable water isotopes (SWIs) contain valuable information on the past climate and phase changes in the hydrologic cycle. Recently, vapor measurements in the polar regions have provided new insights into the effects of snow-related and atmospheric processes ...

AMER GEOPHYSICAL UNION2023

Assessing the simulation of snowfall at Dumont d'Urville, Antarctica, during the YOPP-SH special observing campaign

Alexis Berne, Etienne Gabriel Henri Vignon

The performance of a set of atmospheric models and meteorological reanalyses in the representation of precipitation days in Antarctica is assessed using ground-based observations such as a precipitation gauge and a Micro Rain Radar during the Year Of Polar ...

WILEY2023

Study of backward Brillouin scattering in gas-filled anti-resonant fibers

Luc Thévenaz, Malak Mohamed Hossameldeen Omar Mohamed Galal, Li Zhang

Brillouin scattering in gas shows unmatched gain properties in hollow-core optical fibers filled at high pressure. Here, the gain characteristics are studied for two common gases, namely, N2 and CO2, which show distinct features and are compared to expecte ...

2023

Spatio-Temporal Dynamics of Snow on Central Arctic Sea Ice and its Implications

David Nicholas Wagner

This thesis presents a comprehensive investigation of the interaction between precipitation and wind-induced erosion and deposition of snow on Arctic sea ice. The study uses observations from the 2019-2020 MOSAiC expedition and makes use of the 3D snow cov ...

EPFL2023

Aerobiology over the Southern Ocean – implications for bacterial colonization of Antarctica

Julia Schmale

Parts of the Antarctic are experiencing dramatic ecosystem change due to rapid and record warming, which may weaken biogeographic boundaries and dispersal barriers, increasing the risks of biological invasions. In this study, we collected air samples from ...

2022

Intensification of sub-daily rainfall extremes in a low-rise urban area

Gabriele Manoli

Short-duration extreme rainfall events are the main trigger of flash and pluvial floods in cities. Depending on the local climate zone and urban fabric that affect meteorological variables such as air temperature, humidity, and aerosol concentration, the b ...

2022

Endogenous O-17 Dynamic Nuclear Polarization of Gd-Doped CeO2 from 100 to 370 K

David Lyndon Emsley, Snaedis Björgvinsdóttir, Moreno Lelli, Michael Allan Hope, Georges Guévork Jean-Jacques Menzildjian, Bowen Zhang, Zhuoran Wang

O-17 NMR is an invaluable tool to study the structure and dynamics of oxide materials but remains challenging to apply in many systems. Even with isotopic enrichment, studies of samples with low masses and/or concentrations of the active species, such as t ...

2021

Introducing CRYOWRF v1.0: multiscale atmospheric flow simulations with advanced snow cover modelling

Varun Sharma, Michael Lehning, Franziska Gerber

Accurately simulating snow-cover dynamics and the snow-atmosphere coupling is of major importance for topics as wide-ranging as water resources, natural hazards and climate change impacts with consequences for sea-level rise. We present a new modelling fra ...

2023

Sources, Occurrence and Characteristics of Fluorescent Biological Aerosol Particles Measured over the Pristine Southern Ocean

Julia Schmale, Andrea Baccarini, Robin Lewis Modini, Sebastian Johannes Heinz-Josef Landwehr, Alireza Moallemi

In this study we investigate the occurrence of primary biological aerosol particles (PBAP) over all sectors of the Southern Ocean (SO) based on a 90-day dataset collected during the Antarctic Circumnavigation Expedition (ACE) in austral summer 2016-2017. S ...

2021

Radar measurements of blowing snow off a mountain ridge

Michael Lehning, Wolf Hendrik Huwald, Josué Etienne Gehring, Benjamin Andreas Walter

Modelling and forecasting wind-driven redistribution of snow in mountainous regions with its implications on avalanche danger, mountain hydrology or flood hazard is still a challenging task often lacking in essential details. Measurements of drifting and b ...

2020

Diel quenching of Southern Ocean phytoplankton fluorescence is related to iron limitation

Nina Schuback

Evaluation of photosynthetic competency in time and space is critical for better estimates and models of oceanic primary productivity. This is especially true for areas where the lack of iron (Fe) limits phytoplankton productivity, such as the Southern Oce ...

2020

Synoptic conditions and atmospheric moisture pathways associated with virga and precipitation over coastal Adelie Land in Antarctica

Alexis Berne, Etienne Gabriel Henri Vignon, Nicolas Jean François Jullien

Precipitation falling over the coastal regions of Antarctica often experiences low-level sublimation within the dry katabatic layer. The amount of water that reaches the ground surface is thereby considerably reduced. This paper investigates the synoptic c ...

2020

Hybrid multiple-site mass closure and source apportionment of PM2.5 and aerosol acidity at major cities in the Po Valley

Athanasios Nenes, Spyros Pandis

This study investigates the major chemical components, particle-bound water content, acidity (pH), and major potential sources of PM2.5 in major cities (Belluno, Conegliano, Vicenza, Mestre, Padua, and Rovigo) in the eastern end of the Po Valley. The measu ...

ELSEVIER2020

Pressure Drop and Convective Heat Transfer in Different SiSiC Structures Fabricated by Indirect Additive Manufacturing

Sophia Haussener, Ehsan Rezaei, Alberto Ortona, Maurizio Barbato

The microstructure of porous materials has a significant effect on their transport properties. Engineered cellular ceramics can be designed to exhibit properties at will, thanks to the advances in additive manufacturing. We investigated the heat and mass t ...

ASME2020

The vertical structure of precipitation at two stations in East Antarctica derived from micro rain radars

Alexis Berne, Jacopo Grazioli

Precipitation over Antarctica is the main term in the surface mass balance of the Antarctic ice sheet, which is crucial for the future evolution of the sea level worldwide. Precipitation, however, remains poorly documented and understood mainly because of ...

Copernicus GmbH2019

Investigation of snow melt dynamics and boundary layer processes over a melting snow surface

Sebastian Schlögl

In this thesis, we investigate the surface energy balance of a snow pack for a continuous and a patchy snow cover. Snow surface temperatures have been validated to assess the accuracy of the surface energy balance of a continuous snow pack for individual p ...

EPFL2018

Representation of Horizontal Transport Processes in Snowmelt Modeling by Applying a Footprint Approach

Michael Lehning, Sebastian Schlögl, Charles Fierz

The energy balance of an alpine snow cover significantly changes once the snow cover gets patchy. The local advection of warm air causes above-average snow ablation rates at the upwind edge of the snow patch. As lateral transport processes are typically no ...

FRONTIERS MEDIA SA2018

Wind-packing of snow: How do wind crusts form?

Christian Gabriel Sommer

Wind-packing of snow is the process responsible for the formation of wind slabs and wind crusts. These are hard layers of well-sintered snow often found in the snowpack in mountains as well as in polar regions. Wind-packing affects the local mass balance, ...

EPFL2018