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Prof. Dr. Stephanie Fiedler

Address Pohligstr. 3, 50969 Köln
Room 3.128
Phone +49 (0)221 470- 3693
Fax +49 (0)221 470-5161
Mail stephanie.fiedlerSpamProtectionuni-koeln.de

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Postal Adress:

Universität zu Köln
Institut für Geophysik und Meteorologie
Pohligstrasse 3
D-50969 Köln

Research Topics

My main research interests in energy meteorology are:

  • Physical processes generating strong winds, e.g., desert-dust storms driven by nocturnal lowlevel jets, extra-tropical cyclones or convectively generated cold pools
  • Aerosol effects on radiation and clouds including radiative forcing calculations for a better understanding of climate change
  • Supply of rain water coupled to the spatio-temporal variability of clouds

I work with numerical modelling of the regional and global climate of Earth, theoretical tools to construct simple models and to understand complex models of the Earth system, as well as groundbased and space-borne observations. Additionally, I gained experience with own measurements, e.g., during ocean expeditions with research vessels.

I give an impression of my work with three lines of research activities in the following.

Anthropogenic aerosols

The magnitude of the radiative forcing of anthropogenic aerosols remains one of the key uncertainties in our understanding of climate change. To better understand the climate model spread in aerosol radiative forcing, I have developed the simple plumes parameterisation MACv2.0- SP for optical properties of anthropogenic aerosol and an associated effect on clouds. The code is currently used in  climate models to perform simulations for the “Radiative Forcing Model Inter-comparison Project” (RFMIP) endorsed by CMIP6. I am leading the coordinated RFMIP study on the aerosol radiative forcing with MACv2-SP (RFMIP-SpAer).
The code of MACv2-SP and the historical data is available as supplement of our GMD article (Stevens et al. 2017) or via input4MIPs. We published the future scenarios for MACv2-SP based on CMIP6 emission data in the supplement of our more recent article (Fiedler et al., 2019).

Contact me, if you would like to be involved in it.

Desert-dust storms

Natural dust aerosols contribute most to the aerosol mass on Earth. Dust aerosols are often emitted in North Africa, but both weather forecasts and climate models are known to have a large spread in dust-emission amounts. To aid model development, I have compiled benchmark climatologies from re-analysis data for different dust-emitting processes in North Africa, e.g., nocturnal low-level jets, mobile cyclones and the post-frontal strengthening of trade winds. Estimates of dust emission amounts associated with these processes have been helpful in evaluating weather and climate models at a process level, e.g., a CMIP5 model. Find out more in my publications.

Ocean expeditions

Desert-dust aerosols are emitted in regions where the observational network is sparse. To help getting more observations, I worked on research vessels to collect atmospheric reference data over oceans. In 2017, I have led an own multi-disciplinary expedition to the North Atlantic with RV Maria S. Merian and observed a continental-scale dust outbreak, currently published in the expedition book in the series "Reports on Earth System Science“ at the Max-Planck-Institute for Meteorology. I talked about our experiences in online blogs for MPI-M, and participated in other outreach projects for inspiring the next generation of scientists.

Current Projects and Collaborations

  • Research area director of „Climate modelling and diagnostics“ of the Hans-Ertel-Centre for Weather Research (HErZ), phase III
  • Chief Energy Meteorologist at the Institute of Energy Economics (EWI) at the University of Cologne
  • Leader of coordinated study with MACv2-SP parameterisation for the Radiative Forcing Model Inter-comparison Project (RFMIP) endorsed by CMIP6

Publications

  • Fiedler, S., Crueger, T., D'Agostino, R., Peters, K., Becker, T., Leutwyler, D., Paccini, L., Burdanowitz, J., Buehler, S., Uribe, A., Dauhut, T., Dommenget, D., Fraedrich, K., Jungandreas, L., Maher, N., Naumann, A., Rugenstein, M., Sakradzija, M., Schmidt, H., Sielmann, F., Stephan, C., Timmreck, C., Zhu , X. & Stevens, B.(in press). Simulated tropical precipitation assessed across three major phases of the Coupled Model Intercomparison Project (CMIP). Monthly Weather Review.
  • Orza, J.A.G., Dhital,S., Fiedler, S., Kaplan,M.L., 2020: Large scale upper-level precursors for dust storm formation over North Africa and poleward transport to the Iberian Peninsula. Part I: An observational analysis, Atmospheric Environment, https://doi.org/10.1016/j.atmosenv.2020.117688
  • Fiedler, S., Sokolik, I., 2020: Desert-Dust Aerosols, Reference Module in Earth Systems and Environmental sciences, https://doi.org/10.1016/B978-0-12-409548-9.12413-3
  • Thornhill, G., Collins, W., Olivié, D., Archibald, A., Bauer, S., Checa-Garcia, R., Fiedler, S., Folberth, G., Gjermundsen, A., Horowitz, L., Lamarque, J.-F., Michou, M., Mulcahy, J., Nabat, P., Naik, V., O'Connor, F. M., Paulot, F., Schulz, M., Scott, C. E., Seferian, R., Smith, C., Takemura, T., Tilmes, S., and Weber, J.: Climate-driven chemistry and aerosol feedbacks in CMIP6 Earth system models, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2019-1207, in review
  • Smith, C. J., Kramer, R. J., Myhre, G., Alterskjær, K., Collins, W., Sima, A., Boucher, O., Dufresne, J.-L., Nabat, P., Michou, M., Yukimoto, S., Cole, J., Paynter, D., Shiogama, H., O'Connor, F. M., Robertson, E., Wiltshire, A., Andrews, T., Hannay, C., Miller, R., Nazarenko, L., Kirkevåg, A., Olivié, D., Fiedler, S., Pincus, R., and Forster, P. M., 2020: Effective radiative forcing and adjustments in CMIP6 models, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2019-1212, in review
  • Bellouin, N, Quaas, J., Gryspeerdt, E., Kinne, S., Stier, P., Watson-Parris, D., Boucher, O., Carslaw, K.S., Christensen, M., Daniau, A.-L., Dufresne, J.-L., Feingold, G., Fiedler, S., Forster, P., Gettelman, A., Haywood, J. M., Lohmann, U., Malavelle, F., Mauritsen, T., McCoy, D.T., Myhre, G., Mülmenstädt, J., Neubauer, D., Possner, A., Rugenstein, M., Sato, Y., Schulz, M., Schwartz, S.E., Sourdeval, O., Storelvmo, T., Toll, V., Winker, D., & Stevens, B., 2020: Bounding global aerosol radiative forcing of climate change Reviews of Geophysics,  58, e2019RG000660. https://doi.org/10.1029/2019RG000660
  • Fiedler, S., Kinne, S., Huang, W. T. K., Räisänen, P., O'Donnell, D., Bellouin, N., Stier, P., Merikanto, J., van Noije, T., Makkonen, R., and Lohmann, U., 2019: Anthropogenic aerosol forcing – insights from multiple estimates from aerosol-climate models with reduced complexity, Atmos. Chem. Phys., 19, 6821–6841, doi:10.5194/acp-19-6821-2019.
  • Fiedler, S., Stevens, B., Gidden, M., Smith, S. J., Riahi, K., and van Vuuren, D., 2019: First forcing estimates from the future CMIP6 scenarios of anthropogenic aerosol optical properties and an associated Twomey effect, Geosci. Model Dev., 12, 989-1007, doi:10.5194/gmd-12-989-2019.
  • Mauritsen, T., Bader, J., Becker, T., Behrens, J., Bittner, M., Brokopf, R., Brovkin, V., Claussen, M., Crueger, T., Esch, M., Fast, I., Fiedler, S., Popke, D., Gayler, V., Giorgetta, M., Goll, D., Haak, H., Hagemann, S., Hedemann, C., Hohenegger, C., Ilyina, T., Jahns, T., Jimenez Cuesta de la Otero, D., Jungclaus, J., Kleinen, T., Kloster, S., Kracher, D., Kinne, S., Kleberg, D., Lasslop, G., Kornblueh, L., Marotzke, J., Matei, D., Meraner, K., Mikolajewicz, U., Modali, K., Möbis, B., Müller, W., Nabel, J., Nam, C., Notz, D., Nyawira, S., Paulsen, H., Peters, K., Pincus, R., Pohlmann, H., Pongratz, J., Popp, M., Raddatz, T., Rast, S., Redler, R., Reick, C., Rohrschneider, T., Schemann, V., Schmidt, H., Schnur, R., Schulzweida, U., Six, K., Stein, L., Stemmler, I., Stevens, B., von Storch, J., Tian, F., Voigt, A., de Vrese, P., Wieners, K.-H., Wilkenskjeld, S., Roeckner, E. & Winkler, A., 2019: Developments in the MPI-M Earth System Model version 1.2 (MPI-ESM1.2) and its response to increasing CO2, J. Adv. Mod. Earth Syst., 11, 998-1038. doi:10.1029/2018MS001400.
  • Fiedler, S., 2018. Expedition to the North Atlantic with RV MARIA S. MERIAN. Berichte zur Erdsystemforschung, 211, doi: 10.17617/2.3006588. [full text]
  • Crueger, T., Giorgetta, M. A., Brokopf, R., Esch, M., Fiedler, S., Hohenegger, C., Kornblueh, L., Mauritsen, T., Nam, C., Naumann, A.K., Peters, K., Rast, S., Roeckner, E., Schmidt, H., Sakradzija, M., Vial, J., Vogel, R., and Stevens, B., 2018: ICON-A, the atmosphere component of the ICON Earth System Model. Part II: Model evaluation, J. Adv. Mod. Earth Syst., doi:10.1029/2017MS001233.
  • Giorgetta, M. A., Brokopf, Crueger, T., R., Esch, M., Fiedler, S., Helmert, J., Hohenegger, C., Kornblueh, L., Koehler, M., Manzini, E., Mauritsen, T., Nam, C., Rast, S., Reick, C., Reinert, D., Schmidt, H., Sakradzija, M., Schnur, R., Silvers, L., Wan, H., Zaengl, G., Stevens, B., 2018: ICON-A, the atmosphere component of the ICON Earth System Model. Part I: Model description, J. Adv. Mod. Earth Syst., 10, doi: 10.1029/2017MS001242.
  • Fiedler, S., Kinne, S., and Jansen, F., 2017: Column-integrated optical measurements of aerosol, water vapour and clouds, Chapter in: Wiltshire, K.H, Brodte, E.M., Wilson, A., and Lemke, P., 2017: The Expedition PS102 of the Research Vessel Polarstern to the Atlantic Ocean in 2016, Berichte zur Polar- und Meeresforschung - Reports on polar and marine research, Alfred Wegener Institute for Polar and Marine Research, 713, 99 p.
  • Pokharel, A. K., Kaplan, M. L., and Fiedler, S., 2017: The Role of Jet Adjustment Processes in Sub-Tropical Dust Storms, J. Geophys. Res. - Atmos., 122, 12,122-12,139, doi:10.1002/2017JD026672.
  • Pokharel, A. K., Kaplan, M. L., and Fiedler, S., 2017: Sub-Tropical Dust Storms and Downslope Wind Events, J. Geophys. Res. - Atmos., 122, 10, 191 -10205, doi:10.1002/2017JD026942.
  • Stevens, B. and S. Fiedler, 2017: Reply to "Comment on 'Rethinking the Lower Bound on Aerosol Radiative Forcing'". J. Climate, 30, 6585-6589, doi:10.1175/JCLI-D-17-0034.1.
  • Fiedler, S., Stevens, B., Mauritsen, T., 2017: On the sensitivity of the anthropogenic aerosolforcing to model-internal variability and parameterizing a Twomey effect, J. Adv. Mod. Earth Syst., 9, doi:10.1002/2017MS000932.
  • Stevens, B., Fiedler, S., Kinne, S., Peters, K., Rast, S., Müsse, J., Smith, S. J., and Mauritsen T., 2017: Simple Plumes: A parameterization of anthropogenic aerosol optical properties and an associated Twomey effect for climate studies, Geosci. Model Dev. 10, 433-452, doi:10.5194/gmd-10-433-2017.
  • Fiedler, S., Knippertz, P., Woodward, S., Martin, G., Bellouin, N., Ross, A., Heinold, B., Schepanski, K., Brich, C., Tegen, I., 2016: A process-based analysis of dust-emitting winds in the CMIP5 simulation of HadGEM2-ES, Clim. Dyn., 46: 1107. doi:10.1007/s00382-015-2635-9.
  • Huneeus, N., Basart, S., Fiedler, S., Morcrette, J.-J., Benedetti, A., Mulcahy, J., Terradellas, E., Pérez García-Pando, C., Pejanovic, G., Nickovic, S., Arsenovic, P., Schulz, M., Cuevas, E., Baldasano, J.M., Pey, J., Remy, S., and Cvetkovic, B., 2016: Forecasting the North African dust outbreak towards Europe in April 2011: a model intercomparison, Atmos. Chem. Phys., 16, 4967-4986, doi:10.5194/acp-16-4967-2016.
  • Fiedler, S., Kaplan, M., Knippertz, P., 2015: The importance of Harmattan surges for the emission of North African dust aerosol, 2015, Geophys. Res. Let., 42, 9495-9504, doi:10.1002/2015GL065925.
  • Evan, A., Fiedler, S., Zhao, C., Menut, L., Schepanski, K., Flamant, C., Doherty, O., 2015: Derivation of an observation-based map of North African dust emission, Aeolian Res., 16, 153-162, doi:10.1016/j.aeolia.2015.01.001.
  • Schepanski, S., Knippertz, P., Fiedler, S., Timouk, F., Demarty, J., 2014: The sensitivity of nocturnal low-level jets and near-surface winds over the Sahel to model resolution, initial conditions and boundary-layer setup, Quart. J. R. Met. S., doi:10.1002/qj.2453.
  • Fiedler, S., Schepanski, K., Knippertz, P., Heinold, B., Tegen, I., 2014: How important are cyclones for emitting mineral dust aerosol in North Africa?, Atmos. Chem. Phys., 14, 8983-9000, doi:10.5194/acp-14-8983-2014.
  • Evan, A., Flamant, C., Fiedler, S., Doherty, O, 2014: An analysis of aeolian dust in climate models. Geophys. Res. Lett., 41, doi:10.1002/2014GL060545.
  • Heinold, B., Knippertz, P., Marsham, J. H., Fiedler, S., Dixon, N. S., Schepanski, K., Laurent, B., Tegen, I., 2013: The role of deep convection and low-level jets for dust emissions in West Africa, J. Geophys. Res., 118, 4385–4400, doi:10.1002/jgrd.50402.
  • Fiedler, S., Schepanski, K., Heinold, B., Knippertz, P., Tegen, I., 2013: Climatology of nocturnal low-level jets over North Africa and implications for modeling mineral dust emission, J. Geophys. Res., 118, 6100–6121, doi:10.1002/jgrd.50394.
  • Pietikainen, J.-P., O’Donnell, D., Teichmann, C., Karstens, U., Pfeifer, S., Kazil, J., Podzun, R., Fiedler, S., Kokkola, H., Birmili, W., O’Dowd, C., Baltensperger, U., Weingartner, E., Gehrig, R., Spindler, G., Kulmala, M., Feichter, J., Jacob, D., Laaksonen, A., 2012: The regional aerosol-climate model REMO-HAM, Geosci. Model Dev., 5, 1323–1339, doi: 10.5194/gmd-5-1323-2012.