Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder

Fabian Hoffmann

Fabian Hoffmann is working with Graham Feingold, and others at CIRES and NOAA, to broaden our understanding of clouds in the climate system. He focuses on the process of entrainment and mixing, i.e., the engulfment of cloud-free air into clouds. This processes affect the micro- and macrophysical properties of clouds by changing number and size of droplets, and hence a cloud’s ability to reflect sunlight as well as its probability to produce rain. For this purpose, Fabian is extending his Lagrangian cloud model, a novel method to represent cloud microphysics by individually simulated particles, by a detailed representation of entrainment and mixing. This approach not only fosters our process-level understanding of entrainment and mixing, e.g., on how and where mixing takes place inside a cloud, but also enables an assessment of the macrophysical properties of an entire cloud field, i.e., at a scale at which entrainment and mixing are usually crudely parameterized in other models.

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  • Glassmeier F; Hoffmann F; Johnson JS; Yamaguchi T; Carslaw KS; Feingold G. (Jan 2021). Aerosol-cloud-climate cooling overestimated by ship-track data. Science , 371(6528), 485-+. 10.1126/science.abd3980
  • Unterstrasser, S; Hoffmann, F; Lerch, M. (Oct 2020). Collisional growth in a particle-based cloud microphysical model: insights from column model simulations using LCM1D (v1.0). GEOSCIENTIFIC MODEL DEVELOPMENT , 13(11). 10.5194/gmd-13-5119-2020
  • Hoffmann, F. (Jun 2020). Effects of Entrainment and Mixing on the Wegener-Bergeron-Findeisen Process. JOURNAL OF THE ATMOSPHERIC SCIENCES , 77(6). 10.1175/JAS-D-19-0289.1
  • Hoffmann F; Glassmeier F; Yamaguchi T; Feingold G. (Jun 2020). Liquid Water Path Steady States in Stratocumulus: Insights from Process-Level Emulation and Mixed-Layer Theory. Journal of the Atmospheric Sciences , 77(6), 2203-2215. 10.1175/JAS-D-19-0241.1
  • Maronga, B; Banzhaf, S; Burmeister, C; Esch, T; Forkel, R; Frohlich, D; Fuka, V; Gehrke, KF; Geletic, J; Giersch, S; Gronemeier, T; Gross, G; Heldens, W; Hellsten, A; Hoffmann, F; Inagaki, A; Kadasch, E; Kanani-Suhring, F; Ketelsen, K; Khan, BA; Knigge, C; Knoop, H; Krc, P; Kurppa, M; Maamari, H; Matzarakis, A; Mauder, M; Pallasch, M; Pavlik, D; Pfafferott, J; Resler, J; Rissmann, S; Russo, E; Salim, M; Schrempf, M; Schwenkel, J; Seckmeyer, G; Schubert, S; Suhring, M; von Tils, R; Vollmer, L; Ward, S; Witha, B; Wurps, H; Zeidler, J; Raasch, S. (Mar 2020). Overview of the PALM model system 6.0. GEOSCIENTIFIC MODEL DEVELOPMENT , 13(3). 10.5194/gmd-13-1335-2020
  • Glassmeier, F; Hoffmann, F; Johnson, JS; Yamaguchi, T; Carslaw, KS; Feingold, G. (Aug 2019). An emulator approach to stratocumulus susceptibility. ATMOSPHERIC CHEMISTRY AND PHYSICS , 19(15). 10.5194/acp-19-10191-2019
  • Giersch, S; Brast, M; Hoffmann, F; Raasch, S. (Jul 2019). Toward Large-Eddy Simulations of Dust Devils of Observed Intensity: Effects of Grid Spacing, Background Wind, and Surface Heterogeneities. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES , 124(14). 10.1029/2019JD030513
  • Hoffmann, F; Feingold, G. (Jul 2019). Entrainment and Mixing in Stratocumulus: Effects of a New Explicit Subgrid-Scale Scheme for Large-Eddy Simulations with Particle-Based Microphysics. JOURNAL OF THE ATMOSPHERIC SCIENCES , 76(7). 10.1175/JAS-D-18-0318.1
  • Maahn, M; Hoffmann, F; Shupe, MD; de Boer, G; Matrosov, SY; Luke, EP. (Jun 2019). Can liquid cloud microphysical processes be used for vertically pointing cloud radar calibration?. ATMOSPHERIC MEASUREMENT TECHNIQUES , 12(6). 10.5194/amt-12-3151-2019
  • Hoffmann, F; Yamaguchi, T; Feingold, G. (Jan 2019). Inhomogeneous Mixing in Lagrangian Cloud Models: Effects on the Production of Precipitation Embryos. JOURNAL OF THE ATMOSPHERIC SCIENCES , 76(1). 10.1175/JAS-D-18-0087.1
  • Goren, T., Jan Kazil, Fabian Hoffmann, Takanobu Yamaguchi, Graham Feingold. (Jan 2019). Anthropogenic Air Pollution Delays Marine Stratocumulus Breakup to Open Cells. , 46(23). 10.1029/2019GL085412
  • Noh, Y, D Oh, F Hoffmann and S Raasch. (Nov 2018). A Cloud Microphysics Parameterization for Shallow Cumulus Clouds Based on Lagrangian Cloud Model Simulations. JOURNAL OF THE ATMOSPHERIC SCIENCES , 75(11). 10.1175/JAS-D-18-0080.1
  • Schwenkel, J, F Hoffmann and S Raasch. (Sep 2018). Improving collisional growth in Lagrangian cloud models: development and verification of a new splitting algorithm. GEOSCIENTIFIC MODEL DEVELOPMENT , 11(9). 10.5194/gmd-11-3929-2018
  • Hoffmann F. (Jul 2017). On the limits of Kohler activation theory: how do collision and coalescence affect the activation of aerosols?. Atmospheric Chemistry and Physics , 17(13), 8343-8356. 10.5194/acp-17-8343-2017
  • Hoffmann F; Noh Y; Raasch S. (Jul 2017). The Route to Raindrop Formation in a Shallow Cumulus Cloud Simulated by a Lagrangian Cloud Model. Journal of the Atmospheric Sciences , 74(7), 2125-2142. 10.1175/JAS-D-16-0220.1
  • Unterstrasser S; Hoffmann F; Lerch M. (Apr 2017). Collection/aggregation algorithms in Lagrangian cloud microphysical models: rigorous evaluation in box model simulations. Geoscientific Model Development , 10(4), 1521-1548. 10.5194/gmd-10-1521-2017
  • Spiga A; Barth E; Gu Z; Hoffmann F; Ito J; Jemmett-Smith B; Klose M; Nishizawa S; Raasch S; Rafkin S. (Nov 2016). Large-Eddy Simulations of Dust Devils and Convective Vortices. Space Science Reviews , 203(1-4), 245-275. 10.1007/s11214-016-0284-x
  • Hoffmann F. (Jan 2016). The Effect of Spurious Cloud Edge Supersaturations in Lagrangian Cloud Models: An Analytical and Numerical Study. Monthly Weather Review , 144(1), 107-118. 10.1175/MWR-D-15-0234.1
  • Hoffmann F; Raasch S; Noh Y. (Apr 2015). Entrainment of aerosols and their activation in a shallow cumulus cloud studied with a coupled LCM-LES approach. Atmospheric Research , 156, 43-57. 10.1016/j.atmosres.2014.12.008
  • Maronga B; Gryschka M; Heinze R; Hoffmann F; Kanani-Suehring F; Keck M; Ketelsen K; Letzel MO; Suehring M; Raasch S. (Jan 2015). The Parallelized Large-Eddy Simulation Model (PALM) version 4.0 for atmospheric and oceanic flows: model formulation, recent developments, and future perspectives. Geoscientific Model Development , 8(8), 2515-2551. 10.5194/gmd-8-2515-2015
  • Hoffmann F; Siebert H; Schumacher J; Riechelmann T; Katzwinkel J; Kumar B; Goetzfried P; Raasch S. (Jan 2014). Entrainment and mixing at the interface of shallow cumulus clouds: Results from a combination of observations and simulations. Meteorologische Zeitschrift , 23(4), 349-368. 10.1127/0941-2948/2014/0597