Hans‐Werner Jacobi

Institut de Recherche pour le Développement

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Florent Dominé

Université Laval

M. M. Frey

British Antarctic Survey

Otto Schrems

Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

Lars Kaleschke

Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

M. A. Hutterli

Tofwerk (Switzerland)

Patrick Ginot

Université Grenoble Alpes

Rolf Weller

Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

Samuel Morin

Centre National de Recherches Météorologiques

Paolo Laj

University of Helsinki

Andreas Richter

University of Bremen

Cooperative Institutions

Centre National de la Recherche Scientifique

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Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

Université Grenoble Alpes

University of Colorado Boulder

University of Helsinki

Institut de Recherche pour le Développement

Institut des Géosciences de l'Environnement

Cooperative Institute for Research in Environmental Sciences

Institut polytechnique de Grenoble

Laboratoire de Glaciologie et Géophysique de l’Environnement

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Simulation of the specific surface area of snow using a one-dimensional physical snowpack model: implementation and evaluation for subarctic snow in Alaska

Hans‐Werner Jacobi Florent Dominé William R. Simpson Thomas A. Douglas Matthew Sturm

Abstract. The specific surface area (SSA) of the snow constitutes a powerful parameter to quantify the exchange of matter and energy between the snow and the atmosphere. However, currently no snow physics model can simulate the SSA. Therefore, two different types of empirical parameterizations of the specific surface area (SSA) of snow are implemented into the existing one-dimensional snow physics model CROCUS. The parameterizations are either based on diagnostic equations relating the SSA to parameters like snow type and density or on prognostic equations that describe the change of SSA depending on snow age, snowpack temperature, and the temperature gradient within the snowpack. Simulations with the upgraded CROCUS model were performed for a subarctic snowpack, for which an extensive data set including SSA measurements is available at Fairbanks, Alaska for the winter season 2003/2004. While a reasonable agreement between simulated and observed SSA values is obtained using both parameterizations, the model tends to overestimate the SSA. This overestimation is more pronounced using the diagnostic equations compared to the results of the prognostic equations. Parts of the SSA deviations using both parameterizations can be attributed to differences between simulated and observed snow heights, densities, and temperatures. Therefore, further sensitivity studies regarding the thermal budget of the snowpack were performed. They revealed that reducing the heat conductivity of the snow or increasing the turbulent fluxes at the snow surfaces leads to a slight improvement of the simulated thermal budget of the snowpack compared to the observations. However, their impact on further simulated parameters like snow height and SSA remains small. Including additional physical processes in the snow model may have the potential to advance the simulations of the thermal budget of the snowpack and, thus, the SSA simulations.

Snowpack

Snowmelt

10.5194/tcd-3-681-2009

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Citations (1)

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

Elementa Science of the Anthropocene (2023)

Johannes G. M. Barten L. Ganzeveld Gert‐Jan Steeneveld Byron Blomquist Hélène 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-round flux and concentration observations from the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) campaign and simulations with a single-column atmospheric chemistry and meteorological model (SCM). Based on eddy-covariance O3 surface flux observations, we find a median surface resistance on the order of 20,000 s m−1, resulting in a dry deposition velocity of approximately 0.005 cm s−1. This surface resistance is up to an order of magnitude larger than traditionally used values in many atmospheric chemistry and transport models. The SCM is able to accurately represent the yearly cycle, with maxima above 40 ppb in the winter and minima around 15 ppb at the end of summer. However, the observed springtime ozone depletion events are not captured by the SCM. In winter, the modelled PBL O3 budget is governed by dry deposition at the surface mostly compensated by downward turbulent transport of O3 towards the surface. Advection, which is accounted for implicitly by nudging to reanalysis data, poses a substantial, mostly negative, contribution to the simulated PBL O3 budget in summer. During episodes with low wind speed (<5 m s−1) and shallow PBL (<50 m), the 7-day mean dry deposition removal rate can reach up to 1.0 ppb h−1. Our study highlights the importance of an accurate description of dry deposition to Arctic sea ice in models to quantify the current and future O3 sink in the Arctic, impacting the tropospheric O3 budget, which has been modified in the last century largely due to anthropogenic activities.

Deposition

10.1525/elementa.2022.00086

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Latitudinal distribution of PAN mixing ratios over the Atlantic Ocean

Hans‐Werner Jacobi Rolf Weller Otto Schrems

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Halogens and their role in polar boundary-layer ozone depletion

William R. Simpson R. von Glasow Katja Riedel P. S. Anderson Parisa A. Ariya

Abstract. During springtime in the polar regions, unique photochemistry converts inert halide salts ions (e.g. Br−) into reactive halogen species (e.g. Br atoms and BrO) that deplete ozone in the boundary layer to near zero levels. Since their discovery in the late 1980s, research on ozone depletion events (ODEs) has made great advances; however many key processes remain poorly understood. In this article we review the history, chemistry, dependence on environmental conditions, and impacts of ODEs. This research has shown the central role of bromine photochemistry, but how salts are transported from the ocean and are oxidized to become reactive halogen species in the air is still not fully understood. Halogens other than bromine (chlorine and iodine) are also activated through incompletely understood mechanisms that are probably coupled to bromine chemistry. The main consequence of halogen activation is chemical destruction of ozone, which removes the primary precursor of atmospheric oxidation, and generation of reactive halogen atoms/oxides that become the primary oxidizing species. The different reactivity of halogens as compared to OH and ozone has broad impacts on atmospheric chemistry, including near complete removal and deposition of mercury, alteration of oxidation fates for organic gases, and export of bromine into the free troposphere. Recent changes in the climate of the Arctic and state of the Arctic sea ice cover are likely to have strong effects on halogen activation and ODEs; however, more research is needed to make meaningful predictions of these changes.

Ozone Depletion

Oxidizing agent

Atmospheric chemistry

10.5194/acpd-7-4285-2007

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Citations (53)

Measurements of hydrogen peroxide and formaldehyde exchange between the atmosphere and surface snow at Summit, Greenland

Atmospheric Environment (2002)

Hans‐Werner Jacobi M. M. Frey M. A. Hutterli Roger C. Bales Otto Schrems

Snowpack

Diel vertical migration

Deposition

10.1016/s1352-2310(02)00106-1

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Citations (121)

The French contribution to the atmospheric and cryospheric component of an Arctic Observatory

HAL (Le Centre pour la Communication Scientifique Directe) (2010)

Hans‐Werner Jacobi Philippe Ciais Jean‐Claude Gascard Kathy S. Law Valérie Masson‐Delmotte

Component (thermodynamics)

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Chemical reactions on frozen water surfaces: Environmental consequences

Hans‐Werner Jacobi

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Atmospheric chemical processes and air-snow interactions

M. A. Hutterli Roger C. Bales J. McConnell M. M. Frey Deirdre Belle‐Oudry

H2O2 and HCHO concentrations measured in snowpits and in a shallow core at Siple Dome are presented and discussed in respect topost-depositional processes. Air-firn transfer studies show that physical uptake and release of HCHO and H2O2 by the snow significantlyaffect their concentrations preserved in firn and ice on one hand and atmospheric concentrations on the other hand. Numerical modelssimulating this air-snow transfer successfully reproduce HCHO and H2O2 concentration profiles in snowpits at various Antarctic sites,among other Siple Dome. Sensitivity studies revealed the relative importance of atmospheric concentration, temperature and accumulationrate on the concentrations preserved in ice cores and represent another step towards the quantitative reconstruction of the atmosphericHCHO and H2O2 concentrations and the closely linked oxidizing capacity of the atmosphere based on ice core records. Due to therelatively low accumulation rate and high temperatures at Siple Dome, H2O2 is not well preserved in the firn and ice and drops belowdetection limit with increasing depth. HCHO is low as well, but still above detection limit. The modeling studies and measurements frompits and shallow cores indicate that the Inland Ice core would have the potential to become the best Antarctic HCHO and H2O2paleoclimate record.

Firn

Ice core

Dome (geology)

Rainbow

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Reactions on surfaces of frozen water : Importance of surface reactions for the distribution of reactive compounds in the atmosphere = Reaktionen an gefrorenem Waser : Bedeutung von Oberflächenreaktionen für die Verteilung von reaktiven Verbindungen in der Atmosphäre

Hans‐Werner Jacobi

10.2312/bzpm_0573_2008

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Are photochemical processes on the snow surface important for the exchange of H2O2 and HCHO between the atmosphere and snow

Hans‐Werner Jacobi M. A. Hutterli M. M. Frey Roger C. Bales Otto Schrems

Hydrogen peroxide (H2O2) and formaldehyde (HCHO) are importantreactive intermediates characterizing the oxidation capacityof the atmosphere. Moreover, both compounds are also preservedin ice cores an could be used to reconstruct past atmosphericcompoistions if a quantitative analysis of ice core profilesis possible. While transfer models including only physical processes(e.g. deposition, emission, precipitation, diffusion) have beensuccessfully used to interpret H2O2 and HCHO profiles in shallowice cores at different Arctic and Antarctic locations, recentexperiments have demonstrated that active photochemistry occursabove the snow and within the firn pore space of the upper layersof the snow pack influencing at least nitrogen containing compounds.Therefore, we performed several experiments like gradient measurements,firn air measurements, and snow chamber experiments at Summit,Greenland, to further investigate the impact of these photochemicalprocesses on the boundary layer composition, concentrationsin the snow, and the transfer between both compartments. Wewill present results of combined gradients and firn air measurementsto analyze and quantify fluxes of H2O2 and HCHO in the boundarylayer. In addition, we will compare the fluxes with photochemicalproduction and destruction rates and discuss the implicationsfor snow-enhanced photochemistry for the atmosphere-to-snowtransfer of both compounds.

Firn

Ice core

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