Barbara ERVENS

Earth’ atmosphere undergoes continuous changes due to numerous chemical, physical and biological processes. In the current estimates of radiative forcing, clouds and in particular cloud/aerosol interactions represent one of the largest uncertainties. Aerosol particles act as cloud condensation nuclei (CCN) or ice nuclei (IN) that eventually lead to cloud droplets or ice particles, respectively. The aqueous p hase of cloud droplets and wet particles represents a medium where efficient chemical reactions can occur that lead to the modification of the composition of aerosol particles, cloud/rain water and the surrounding gas phase. Less attention has been given to the role of biological processes that occur in clouds. Microorganisms, such as bacteria, cannot not only act as IN but they also utilize organic substrates in cloud droplets and transform them into CO₂ and other products, in competition to chemical processes. Thus, in order to understand the formation, evolution and radiative impact of clouds interdisciplinary efforts are needed to improve upon the description of relevant processes on all scales.

My research focuses on the development and application of small-scale models that describe in detail chemical, microphysical and biological processes in clouds.

Find a complete publication list sorted by topics here.
 

Previous work includes
 

• the development of detailed CHEMICAL mechanisms of reactions occurring in cloud droplets. My early work was the development of the chemical aqueous phase radical mechanism (CAPRAM). In addition, I was one of the first researchers who suggested that in addition to sulfate, also organic aerosol may be formed in cloud droplets and in aqueous aerosol (aqSOA).

• the implementation and analysis of MICROPHYSICAL data and processes in cloud models. We showed that the representation of CCN properties can be largely simplified for most cases. In detailed model studies of ice microphysics, we explored the sensitivities and key parameters of ice nucleation in mixed-phase clouds.

Currently, my work is focused on BIOLOGICAL processes in clouds within the project MOBIDIC (Modeling Biologically-Driven Processes in Clouds) project. We explore by means of model studies on various scales, processes of biological particles (bacteria) in the atmosphere. These processes include emission, dospersion and transport but also bacterial cell growth/multiplication and the utilization of organics by bacteria in cloud water.


 

RESEARCH EXPERIENCE

2021 – present Senior Scientist, National Centre for Scientific Research (CNRS), Institute of Chemistry of Clermont-Ferrand, University Clermont Auvergne,

2018 – 2021     Research Scientist, Institute of Chemistry of Clermont-Ferrand, University Clermont Auvergne

2011 – 2018      Research Scientist III, Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, and NOAA, Earth System Research Laboratory, Chemical Sciences Division, Boulder, CO, USA

2008 - 2011       Research Scientist II, Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, and NOAA, Earth System Research Laboratory, Chemical Sciences Division, Boulder, CO, USA

2005 – 2008      Research Scientist I, Atmospheric Science Department, Colorado State University, Fort Collins, and NOAA, Earth System Research Laboratory, Chemical Sciences Division, Boulder, CO, USA

2002 – 2004      Postdoctoral Fellow, Cooperative Institute for Research in the Atmosphere (CIRA), Colorado State University, Fort Collins, and NOAA, Environmental Technology Laboratory, Boulder, CO, USA

2001 – 2002     Postdoctoral Fellow, Institute for Tropospheric Research, Leipzig, Germany

1998 – 2001      Research Assistant, Institute for Tropospheric Research, Leipzig, Germany

1997 – 1998      Research Assistant, Institute for Physical and Theoretical Chemistry, University Essen, Germany

MOST RECENT PUBLICATIONS

Link to Full publication list (Google Scholar)

Barth, M. C., B. Ervens, H. Herrmann, A. Tilgner, V. F. McNeill, W. G. Tsui, L. Deguillaume, N. Chaumerliac, A. Carlton, and S. M. Lance, Box Model Intercomparison of Cloud Chemistry, J. Geophys. Res., https://doi.org/10.1029/2021JD035486, 2021, in press.

Khaled, A., Zhang, M., and Ervens, B.: The number fraction of iron-containing particles affects OH, HO₂ and H₂O₂ budgets in the atmospheric aqueous phase, Atmos. Chem. Phys. Discuss. [preprint], https://doi.org/10.5194/acp-2021-483, in review, 2021.

Braga, R. C., Rosenfeld, D., Krüger, O. O., Ervens, B., Holanda, B. A., Wendisch, M., Krisna, T., Pöschl, U., Andreae, M. O., Voigt, C., and Pöhlker, M. L., Linear relationship between effective radius and precipitation water content near the top of convective clouds, Atmos. Chem. Phys., 21, 14079–14088, https://doi.org/10.5194/acp-21-14079-2021, 2021.

Pöhlker, M. L., Zhang, M., Campos Braga, R., Krüger, O. O., Pöschl, U., and Ervens, B.: Aitken mode particles as CCN in aerosol- and updraft-sensitive regimes of cloud droplet formation, Atmos. Chem. Phys., 21, 11723–11740, https://doi.org/10.5194/acp-21-11723-2021, 2021.

Braga, R. C., Ervens, B., Rosenfeld, D., Andreae, M. O., Förster, J.-D., Fütterer, D., Hernández Pardo, L., Holanda, B. A., Jurkat, T., Krüger, O. O., Lauer, O., Machado, L. A. T., Pöhlker, C., Sauer, D., Voigt, C., Walser, A., Wendisch, M., Pöschl, U., and Pöhlker, M. L.: Cloud droplet number closure for tropical convective clouds during the ACRIDICON–CHUVA campaign, Atmos. Chem. Phys. Discuss. [preprint], https://doi.org/10.5194/acp-2021-80, 2021, in press.

Zhang, M., Khaled, A., Amato, P., Delort, A.-M., and Ervens, B.: Sensitivities to biological aerosol particle properties and ageing processes: potential implications for aerosol–cloud interactions and optical properties, Atmos. Chem. Phys., 21, 3699 - 3724, https://doi.org/10.5194/acp-21-3699-2021, 2021. (editor's highlight)

Khaled, A., Zhang, M., Amato, P., Delort, A.-M., and Ervens, B.: Biodegradation by bacteria in clouds: An underestimated sink for some organics in the atmospheric multiphase system, Atmos. Chem. Phys., 21, 3123–3141, https://doi.org/10.5194/acp-21-3123-2021, 2021.

Jaber, S., Joly, M., Brissy, M., Leremboure, M., Khaled, A., Ervens, B., and Delort, A.-M.: Biotic and abiotic transformation of amino acids in cloud water: Experimental studies and atmospheric implications, Biogeosciences, 18, 1067–1080, https://doi.org/10.5194/bg-18-1067-2021, 2021.

Jaber, S., A. Lallement, M. Sancelme, G. Mailhot, B. Ervens and A. Delort, Biodegradation of phenol and catechol in cloud water. Comparison with radical chemistry, Atmos. Chem. Phys., 20, 4987–4997, https://doi.org/10.5194/acp-20-4987-2020, 2020.

Ervens, B. and P. Amato, The global impact of bacterial processes on carbon mass, Atmos. Chem. Phys., 20, 1777–1794, doi.org/10.5194/acp-20-1777-2020, 2020.