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Your search keyword '"Cathrine Lund Myhre"' showing total 2 results
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1. A vegetation control on seasonal variations in global atmospheric mercury concentrations

Author

Ingvar Wängberg, Cathrine Lund Myhre, Lynwill Martin, Casper Labuschagne, Aurélien Dommergue, Katriina Kyllönen, Johannes Bieser, Martin Jiskra, Thumeka Mkololo, Olivier Magand, Michel Ramonet, Doug Worthy, Jeroen E. Sonke, Daniel Obrist, Katrine Aspmo Pfaffhuber, Ralf Ebinghaus, Géochimie des Isotopes Stables Non-Traditionnels, Géosciences Environnement Toulouse ( GET ), Institut de Recherche pour le Développement ( IRD ) -Université Paul Sabatier - Toulouse 3 ( UPS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut de Recherche pour le Développement ( IRD ) -Université Paul Sabatier - Toulouse 3 ( UPS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ), Desert Research Institute ( DRI ), GKSS-Research Center, Institute for Coastal Research, South African Weather Service ( SAWS ), Centre National de la Recherche Scientifique ( CNRS ), Laboratoire de glaciologie et géophysique de l'environnement ( LGGE ), Observatoire des Sciences de l'Univers de Grenoble ( OSUG ), Université Joseph Fourier - Grenoble 1 ( UJF ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes ( UGA ) -Université Joseph Fourier - Grenoble 1 ( UJF ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes ( UGA ) -Centre National de la Recherche Scientifique ( CNRS ), Géosciences Environnement Toulouse (GET), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), University of Basel (Unibas), University of Massachusetts [Lowell] (UMass Lowell), University of Massachusetts System (UMASS), Helmholtz-Zentrum Geesthacht (GKSS), Norwegian Institute for Air Research (NILU), IVL Swedish Environmental Research Institute Ltd, Finnish Meteorological Institute (FMI), Climate Research Division [Toronto], Environment and Climate Change Canada, South African Weather Service (SAWS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), ICOS-RAMCES (ICOS-RAMCES), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut des Géosciences de l’Environnement (IGE), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Recherche pour le Développement (IRD)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), European Project: 265113,EC:FP7:ENV,FP7-ENV-2010,GMOS(2010), European Project: 657195,H2020,H2020-MSCA-IF-2014,MEROXRE(2015), European Project: 258537,EC:FP7:ERC,ERC-2010-StG_20091028,MERCURY ISOTOPES(2010), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Swedish Environmental Research Institute (IVL), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])

Subjects
[ SDU.OCEAN ] Sciences of the Universe [physics]/Ocean, Atmosphere, 010504 meteorology & atmospheric sciences, Birkenesobservatoriet, chemistry.chemical_element, 010501 environmental sciences, Atmospheric sciences, Photosynthesis, 01 natural sciences, Kvikksølv, Latitude, medicine, [ SDU.ENVI ] Sciences of the Universe [physics]/Continental interfaces, environment, Atmosphere and climate, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Birkenes Observatory, Southern Hemisphere, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Northern Hemisphere, Primary production, Mercury, 15. Life on land, Seasonality, medicine.disease, Atmosfære og klima, Mercury (element), chemistry, 13. Climate action, Atmospheric chemistry, General Earth and Planetary Sciences, Environmental science
Abstract

International audience; Anthropogenic mercury emissions are transported through the atmosphere as gaseous elemental mercury (Hg(0)) before they are deposited to Earth’s surface. Strong seasonality in atmospheric Hg(0) concentrations in the Northern Hemisphere has been explained by two factors: anthropogenic Hg(0) emissions are thought to peak in winter due to higher energy consumption, and atmospheric oxidation rates of Hg(0) are faster in summer. Oxidation-driven Hg(0) seasonality should be equally pronounced in the Southern Hemisphere, which is inconsistent with observations of constant year-round Hg(0) levels. Here, we assess the role of Hg(0) uptake by vegetation as an alternative mechanism for driving Hg(0) seasonality. We find that at terrestrial sites in the Northern Hemisphere, Hg(0) co-varies with CO$_2$, which is known to exhibit a minimum in summer when CO$_2$ is assimilated by vegetation. The amplitude of seasonal oscillations in the atmospheric Hg(0) concentration increases with latitude and is larger at inland terrestrial sites than coastal sites. Using satellite data, we find that the photosynthetic activity of vegetation correlates with Hg(0) levels at individual sites and across continents. We suggest that terrestrial vegetation acts as a global Hg(0) pump, which can contribute to seasonal variations of atmospheric Hg(0), and that decreasing Hg(0) levels in the Northern Hemisphere over the past 20 years can be partly attributed to increased terrestrial net primary production.

Published
2018
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2. Jury is still out on the radiative forcing by black carbon

Author

Olivier Boucher, Rong Wang, Bjørn Hallvard Samset, Øivind Hodnebrog, Gunnar Myhre, Nick Schutgens, Cathrine Lund Myhre, Philip Stier, Yves Balkanski, Johannes Quaas, Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Modelling the Earth Response to Multiple Anthropogenic Interactions and Dynamics (MERMAID), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Center for International Climate and Environmental Research [Oslo] (CICERO), University of Oslo (UiO), Fudan University [Shanghai], Earth and Climate, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)

Subjects
Physics, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Mass absorption, Multidisciplinary, 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Carbon black, 010501 environmental sciences, Radiative forcing, Atmospheric sciences, 01 natural sciences, Aerosol, Complement observations, 13. Climate action, Climate impact, 0105 earth and related environmental sciences
Abstract

International audience; Peng et al. (1) conclude that a fast increase in the mass absorption cross-section (MAC) of black carbon (BC) in urban environments leads to significantly increased estimates of the BC radiative forcing (RF). Their chamber measurements are highly valuable and complement observations performed in ambient conditions, but their "enhancement factor" relative to an unspec-ified baseline may not be directly comparable to values used or simulated in global aerosol models. MAC, a key parameter in our understanding of the net BC climate impact, is indeed a more relevant quantity to examine. A fast MAC enhancement in polluted environments as the BC gets coated with organic and inorganic species is consistent with recent findings (2, 3). Global models used in AeroCom [table S1 in Peng et al. (1), ref. 4] have an average MAC of ∼8 m 2 ·g −1 at 550 nm. This value is reflecting reported measurements, although there is a large spatial and seasonal variability in ambient MAC for aged particles, with values of ∼10 m 2 ·g −1 at a rural Northern Chinese site (2) (at 678 nm); 6-14 m 2 ·g −1 at rural, urban, and high-altitude Indian locations (5) (at 678 nm); and ∼6 m 2 ·g −1 at an Arctic site (6) (at 522 nm). Coating of BC by soluble species not only enhances absorption of solar radiation but also reduces the BC atmospheric lifetime (7). Fig. 1 shows an offset between the increase in average MAC value with faster BC aging and an overall shorter BC lifetime, resulting in a near-constant BC aerosol absorption optical depth and RF with aging time. Furthermore, current global aerosol models frequently have a too long BC lifetime and consequently overestimate BC concentrations downwind from source regions (8). According to Peng et al. (1), their BC absorption enhancement factor of 2.4 is also an upper bound, only reached after 5 (Beijing) to 18 (Houston) h, and possibly longer in cleaner environments. Such timescales are not small compared with the BC atmospheric lifetime of 3-5 d, especially considering that dilution effects may lengthen the aging timescale in the real atmosphere compared with the static chamber measurements performed by Peng et al. It is unclear how representative these measurements are for global and annual averages, but we know that generalizations can introduce serious errors due to spatial and temporal sampling issues (9). This implies that a simple scaling of the BC RF by the absorption enhancement factor measured by Peng et al.-as performed by the authors in their table S1 and figure 4, and extended in the commentary (10)-is overly simplistic. In conclusion, although we welcome the advances made by Peng et al., their conclusion of a +0.45 [0.21-0.80] W·m −2 additional RF due to a large BC enhancement factor is premature. The jury is still out on the question of the net climate impact of BC and how much climate cobenefit will result from the necessary mitigation of BC emissions. Reducing the uncertainty on the BC forcing requires better constraining BC MAC and atmospheric lifetime in global aerosol models.

Published
2016
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