Publications related to Eddy covariance

On the importance of the humidity flux for the surface mass balance in the accumulation zone of the Greenland Ice Sheet

It is highly uncertain how the humidity flux between the snow surface and the atmosphere contributes to the surface mass balance (SMB) of the interior Greenland Ice Sheet (GrIS). Due to sparse observations, evaluations of the simulated humidity flux are li ...

Copernicus Gesellschaft Mbh2024

Assessing sublimation during snow transport and sublimation effects on the isotopic composition of water vapor

Armin Sigmund

Sublimation influences the water storage in snow covers and glaciers, which is important for water use and projections of the sea level rise. Yet, it is challenging to quantify sublimation for large areas or in conditions of snow transport. In-situ measure ...

EPFL2023

Low ozone dry deposition rates to sea ice during the MOSAiC field campaign: Implications for the Arctic boundary layer ozone budget

Julia Schmale, Ivo Fabio Beck, Hélène Paule Angot

Dry deposition to the surface is one of the main removal pathways of tropospheric ozone (O3). We quantified for the first time the impact of O3 deposition to the Arctic sea ice on the planetary boundary layer (PBL) O3 concentration and budget using year-ro ...

2023

Spatial Variability of Turbulent Mixing From an Underwater Glider in a Large, Deep, Stratified Lake

Alfred Johny Wüest, Damien Bouffard, Sébastien Lavanchy, Oscar Rodrigo Sepúlveda Steiner, Bieito Fernandez Castro, Alexander Lebaron Forrest

Recent efforts using microstructure turbulence measurements have contributed to our understanding of the overall energy budget in lakes and linkages to vertical fluxes. A paucity of lake-wide turbulence measurements hinders our ability to assess how repres ...

AMER GEOPHYSICAL UNION2023

Evaluation of 30 urban land surface models in the Urban-PLUMBER project: Phase 1 results

Gabriele Manoli, Matthias Roth

Accurately predicting weather and climate in cities is critical for safeguarding human health and strengthening urban resilience. Multimodel evaluations can lead to model improvements; however, there have been no major intercomparisons of urban-focussed la ...

Wiley2023

A Novel Method to Quantify Near-Surface Boundary-Layer Dynamics at Ultra-High Spatio-Temporal Resolution

Michael Lehning, Dylan Stewart Reynolds, Tobias Jonas, Michael Haugeneder

The lateral transport of heat above abrupt (sub-)metre-scale steps in land surface temperature influences the local surface energy balance. We present a novel experimental method to investigate the stratification and dynamics of the near-surface atmospheri ...

SPRINGER2023

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

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

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

The role of air-sea fluxes for the water vapour isotope signals in the cold and warm sectors of extratropical cyclones over the Southern Ocean

Josué Etienne Gehring, Irina Gorodetskaya

Meridional atmospheric transport is an important process in the climate system and has implications for the availability of heat and moisture at high latitudes. Near-surface cold and warm temperature advection over the ocean in the context of extratropical ...

Copernicus Gesellschaft Mbh2021

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

Impact of evapotranspiration on the local microclimate

Jean-Louis Scartezzini, Dasaraden Mauree, Silvia Coccolo

Climate change is having and will have drastic consequences for high density populated areas such as cities. There is thus a need to develop more tools to evaluate new strategies for adaptation to and mitigation of changing temperatures. Additional functio ...

2019

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

Improving surface heat flux estimation for a large lake through model optimization and two-point calibration: The case of Lake Geneva

David Andrew Barry, Ulrich Lemmin, Damien Bouffard, Andrea Cimatoribus, Abolfazl Irani Rahaghi

Net Surface Heat Flux (SurHF) was estimated from 2008 to 2014 for Lake Geneva (Switzerland/France), using long‐term temperature depth profiles at two locations, hourly maps of reanalysis meteorological data from a numerical weather model and lake surface w ...

Association for the Sciences of Limnology and Oceanography (ASLO)2018

Large-scale and meso-scale surface heat flux patterns of Lake Geneva

Abolfazl Irani Rahaghi

Diverse studies have confirmed the adverse impact of global climate change in lakes. In order to establish effective water quality management policies, it is essential to understand how the heat exchange between the atmosphere and the lake evolves under th ...

EPFL2018

Small-scale spatio-temporal dynamics of snowmelt and its influence on runoff generation in a high Alpine catchment

Tristan Jonas Brauchli

Snow is one of the most complex materials occurring in nature. In clouds, it can be seen either as a crystal with various shapes or as a freshwater resource that will fall down to the Earth's surface. Once on the ground, it can be described as a thermodyna ...

EPFL2018

How do patchy snow covers affect turbulent sensible heat fluxes? – Numerical analysis and experimental findings

Michael Lehning, Sebastian Schlögl

The surface energy balance of a snow cover significantly changes once the snow cover gets patchy. The substantial progress in knowledge about the surface energy balance of patchy snow covers is a mandatory requirement to reduce biases in flux parameterizat ...

2017

How do Stability Corrections Perform in the Stable Boundary Layer Over Snow?

Michael Lehning, Wolf Hendrik Huwald, Sebastian Schlögl, Koichi Nishimura

We assess sensible heat-flux parametrizations in stable conditions over snow surfaces by testing and developing stability correction functions for two alpine and two polar test sites. Five turbulence datasets are analyzed with respect to, (a) the validity ...

2017

Evaporation from cultivated and semi-wild Sudanian Savanna in west Africa

Marc Parlange, Natalie Claire Ceperley, Theophile Mande, Nicolaas Cornelis van de Giesen

Rain-fed farming is the primary livelihood of semi-arid west Africa. Changes in land cover have the potential to affect precipitation, the critical resource for production. Turbulent flux measurements from two eddy-covariance towers and additional observat ...

European Geosciences Union2017

Measurement of the impact of buildings on meteorological variables

Jean-Louis Scartezzini, Dasaraden Mauree, Laurent Deschamps, Pierre Loesch, Paul Becquelin

A meteorological tower was installed on the EPFL campus in a semi-urban environment for the high frequency monitoring of the micro-climate. This project was done in the larger framework of the measurement of the meteorological profiles and also a quantific ...

2017

Adapting tilt corrections and the governing flow equations for steep, fully three-dimensional, mountainous terrain

Wolf Hendrik Huwald, Marc Parlange, Holly Jayne Oldroyd, Eric Richard Pardyjak

In recent studies of atmospheric turbulent surface exchange in complex terrain, questions arise concerning velocity-sensor tilt corrections and the governing flow equations for coordinate systems aligned with steep slopes. The standard planar-fit method, a ...

2016

Turbulent Transport in Complex, Alpine Environments

Holly Jayne Oldroyd

Turbulent exchanges between the atmosphere and the underlying surface transport heat, moisture, momentum and pollutants, and thus understanding them is crucial to water resource management, meteorological predictions, climate modeling, wind energy producti ...

EPFL2015