Atmospheric Complexity
The group uses methods from theoretical physics to describe and model atmospheric processes. The aim is to capture emergent aspects, e.g. self-organization, that originate from small scales but can impact on larger scales. We use high-resolution simulations and observational data and make simplified, conceptual, models to capture key aspects of atmospheric complexity.
Workshop on spatial organisation of convection, clouds and precipitation
How do clouds influence the climate system? How do they form intense precipitation? Such questions have challenged atmospheric science for decades. High-resolution simulations and observations bring us closer to answering them, yet, fundamental processes are not understood.

Satellite image by the Global Precipitation Measurement mission (NASA).
This is because clouds organize on a range of scales, scales interact and precipitation is a result of abrupt changes of phases, leading to abruptness, e.g. intermittancy, in the moisture dynamics. Furthermore, convective-type cloud has been shown to produce unexpectedly strong precipitation intensity, not explained by equilibrium thermodynamics.
The team uses methods from theoretical physics to describe and model atmospheric processes. The aim is to capture emergent aspects, e.g. self-organization, that originate from small scales but can impact on larger scales. We use high-resolution simulations and observational data and make simplified, conceptual, models to capture key aspects of atmospheric complexity.
M.Sc. project idea
In simulations, cold pools are found to produce near circular shapes as they spread. In a recent paper, we described this spreading in a simple mathematical model, where circles collide in space to produce new rain cells. A possible MSc project would take this idea further, to allow for a depletion effect, where circles that have spread will make it less likely for new events to occur in the same location.
- Center for Ice and Climate, Niels Bohr Institute
- Danish Meteorological Institute
- Max Planck Institute for Meteorology, Hamburg, Germany
- Swedish Hydrological and Meteorological Institute, Norrköping, Sweden
- University of Adelaide, Australia (Prof. Seth Westra)
- TU Delft and KNMI Netherlands (Kai Lochbihler)
List of relevant publications (chronological order)
- M. B. Fournier and J. O. Haerter, Tracking the gust fronts of convective cold pools (under review)
- J. O. Haerter, Stephen J. Boeing, O. Henneberg, S. B. Nissen, Circling in on convective organization (accepted in GRL, 2019)
- J. O. Haerter, Convective self-aggregation as a cold pool driven critical phenomenon, Geophys. Res. Letts (2019)
- EOS Research Spotlight: Can patches of cold air cause thunderstorms to cluster?
- C. Moseley, O. Henneberg, J. O. Haerter, A statistical model for isolated convective precipitation events, JAMES (2019)
- J. O. Haerter and L. Schlemmer, Intensified cold pool dynamics under stronger surface heating, Geophys. Res. Letts 45 (2018)
- J. O. Haerter, P. Berg, C. Moseley, Precipitation onset as the temporal reference for convective self-organization, Geophysical Research Letters, 44, 12, 6450–6459 (2017), DOI: 10.1002/2017GL073342
- J. O. Haerter, A. Díaz-Guilera, and M. Á. Serrano, Noise-induced polarization switching in complex networks Phys. Rev. E 95, 042305 (2017)
- C. Moseley, C. Hohenegger, P. Berg, J. O. Haerter, Intensification of convective extremes driven by cloud-cloud interaction. Nature Geoscience 9, 748–752 (2016)
- B. Eggert, P. Berg, J. O. Haerter, D. Jacob, and C. Moseley, Temporal and spatial scaling impacts on extreme precipitation. Atmospheric Chemistry and Physics 15 (10) 5957-5971 (2015)
- J. O. Haerter, B. Eggert, C. Moseley, C. Piani, P. Berg, Statistical precipitation bias correction of gridded model data using point measurements. Geophys. Res. Lett., 42, 1–11 (2015).
- C. Moseley, P. Berg, J. O. Haerter, Probing the precipitation life‐cycle by iterative rain cell tracking. Journal of Geophysical Research: Atmospheres 118 (24), 13,361–13,370 (2013)
- P. Berg, C. Moseley, J. O. Haerter, Strong increase in convective precipitation in response to higher temperatures, Nature Geoscience 6, 181-185 (2013)
- Nature Research Highlight: Harder rains in a hotter climate, Nature 494, 284 (2013)
- C. Piani and J. O. Haerter, Two dimensional bias correction of temperature and precipitation copulas in climate models, Geoph. Res. Lett. 39, L20401 (2012)
- C. Chen, J. O. Haerter, S. Hagemann, C. Piani, On the contribution of statistical bias correction to the uncertainty in the projected hydrological cycle, Geophysical Research Letters, 38, L20403 (2011)
- S. Hagemann, C. Chen, J. O. Haerter, J. Heinke, D. Gerten, C. Piani, Impact of a Statistical Bias Correction on the Projected Hydrological Changes Obtained from three GCMs and Two Hydrology Models, Journal of Hydrometeorology, 12, 556-578 (2011)
- P. Berg and J. O. Haerter, Unexpected increase in precipitation intensity with temperature — A result of mixing of precipitation types?, Atmospheric Research, DOI: 10.1016/.atmosres.2011.05.012 (2011)
- J. O. Haerter, S. Hagemann, C. Moseley, C. Piani, Climate model bias correction and the role of timescales, Hydrology and Earth System Sciences, 15, 1065-1079 (2011)
- C. Piani, G. P. Weedon, M. Best, S. M. Gomes, P. Gomes, S. Hagemann, J. O. Haerter, Statistical bias correction of global simulated daily precipitation and temperature for the application of hydrological models, Journal of Hydrology, 395, 199-215 (2010)
- J. O. Haerter, P. Berg and S. Hagemann, Heavy rain intensity distributions on varying time scales and at different temperatures, Journal of Geophysical Research, 115, D17102 (2010)
- C. Piani, J. O. Haerter and E. Coppola, Statistical bias correction for daily precipitation in regional climate models over Europe, Theoretical and Applied Climatology, DOI: 10.1007/s00704-009-0134-9 (2010)
- J. O. Haerter, E. Roeckner, L. Tomassini, Jin-Song von Storch, Parametric uncertainty effects on aerosol radiative forcing, Geophysical Research Letters, 36, L15707 (2009)
- P. Berg, J. O. Haerter, P. Thejll, C. Piani, S. Hagemann, J. H. Christensen, Seasonal characteristics of the relationship between daily precipitation intensity and surface temperature, Journal of Geophysical Research, 114, D18, DOI:10.1029/2009JD012008 (2009)
- J. O. Haerter and P. Berg, Unexpected rise in extreme precipitation caused by a shift in rain type?, Nature Geoscience, 2, 372 (2009)
Further publications by team members
For a full list of publications for each of the team members, please refer to their respective publication lists.
Congrats to Herman!
For a very successful thesis defense. Best wishes for the future.
Feb 20th, 2019
Thesis defense by Herman Fuglestvedt
Niels Bohr Institute, Blegdamsvej 17, Aud D
Feb 20th, 2019, 10 a.m.
Title: A Conceptual Model for Self-Organisation of Precipitating Convection
Jan 24th, 2019
Paper accepted in the Journal of Advances in Earth System Modeling (JAMES)
Jan 10th, 2019
Marielle successfully defended her M.Sc. thesis, congratulations and all the best for the future!
Thesis title: Tracking Convective Cold Pools - A study of cloud interactions
Dec 10th, 2018
Marielle will hand in her MSc thesis on Dec 18th, and her thesis defense will be on Jan 10th, 10 a.m. in Auditorium D.
Thesis title: Tracking Convective Cold Pools - A study of cloud interactions
Nov 1st, 2018
Enrico Maria Fenoaltea start a MSc project on human decision making under complex circumstances, using the example system chess.
Big welcome!
>> read more
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Sept 1st, 2018
Christian starts a MSc project in Atmospheric Complexity.
Welcome to the team!
>> read more
Sept 1st, 2018
Christian starts a MSc project in Atmospheric Complexity
Welcome to the team!
>> read more
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May 31, 2018: New paper published in Geophysical Research Letters:
Jan O. Haerter & Linda Schlemmer: Intensified cold-pool dynamics under stronger surface heating
key result: A new feedback between precipitation and cold pool dynamics, which could explain the super-Clausius-Clapeyron increase of convective precipitation extremes.

Histograms of near-surface temperature. Note the broadening in the course of precipitation (details: GRL)
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May 28, 2018: Bettina Meyer will join the Atmospheric Complexity group as a postdoc on June 15th, welcome!
Bettina has recently completed her Ph.D. at ETH Zürich in collaboration with Caltech.
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May 4, 2018: Experimental Economics meets Statistical Physics
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Apr 26, 2018: A warm welcome to Kai Lochbihler from TU Delft/KNMI, who will be visiting our group for several weeks. We will be collaborating on convective organization in a range of systems.
Kai is currently a Ph.D. student with Geert Lenderink (KNMI) and Pier Siebesma (TU Delft).
He has worked on extreme convective precipitation and the possible exceedance of the Clausius-Clapeyron relation.
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Apr 25, 2018: Olga Henneberg will be giving a talk at the AMS meeting in Vancouver in July: "From Cold Pool Interaction to Extreme Precipitation"
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Apr 25, 2018: Thanks to all for the great workshop on convective self-organization!
We hope that this event has helped bring about new ideas and get people together.
Check back for slides and photos of this event on the webpage below.
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Dec 15, 2017: Jan receives ERC Consolidator Grant
We are thankful for this generous grant offered by the European Commission!
“Complex Fluids” brings together the complex systems and geophysical fluid dynamics fields. The focus is on talks with a conceptual modeling view on complexity, e.g. as arising in earth's atmosphere and ocean, in biology, or within the solid earth.
Sign up for the mailing list
We encourage subscription to the Complex Fluids mailing list, to receive information about upcoming seminars.
For suggested speakers and queries please contactJan O. Haerter, Peter Ditlevsen, Markus Jochum, Joachim Mathiesen, Eigil Kaas, or Mogens H. Jensen.
Scope
The scope of this seminar is to encourage models that describe complex processes in fluids, e.g. those involving some type of emergent aspect, self-organization, bistability, oscillations, scale interactions, long-ranged order, you name it ;) Examples are bistability in the climate system, convective processes, extreme events, self-similarity and pattern formation in geology or atmospheric processes, interactions and feedbacks between atmosphere and biosphere, etc.
Conceptual models
We are interested in conceptual (but not necessarily complicated) models that are able to capture the core dynamical processes and (some of) the feedbacks in a fluid dynamical system, without getting lost in comprehensive models and many parameters. The sacrifice may sometimes be, that not all processes are considered, and that quantitative detail is missing.
The gain however lies in the theoretical understanding of the model and thereby at least some aspects of reality. We therefore encourage talks that offer a speculate, provocative view on crucial processes, e.g. in the climate system, that are currently not well understood or uncertain.
When and where
Wednesdays at noon (communal informal lunch). Presentations start around 12:30 and normally take around 45 minutes. Initially, the seminar will be approximately twice per month.
Where? Kc7, C-floor of K-building, Blegdamsvej 17, 2100 København Ø.
Jan O. HaerterNiels Bohr Institute University of Copenhagen |
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Workshop on spatial organisation of convection, clouds and precipitation
The workshop talks will be on the following themes:
- Detecting and understanding regimes of organisation
- Organisation as a tool for model evaluation
- Introducing organisation in climate models
Organisation Committee: Jan Härter, Bettina Meyer, Chiel van Heerwaarden, Franziska Glassmeier, Leif Danby, Steef Böing
This workshop aims to provide a platform to present ongoing work and open questions about organised and self-organised phenomena in cloud fields. We want to bring together the communities working on climate physics, statistical mechanics and meso-scale meteorology. The workshop will be organised around 3 topics, mentioned below with some examples of the type of questions we would like to address.
Some of the presentations will be on convection, but we are keen to also involve scientists working on related topics, such as soil-moisture and ocean (e.g. ocean mixed-layer) feedbacks.
A) Detecting and understanding regimes of organisation
- How can we quantify organisation?
- How can we detect the existence of specific regimes of organisation?
- What ingredients are required to model the emergence and evolution of organisation?
- What can we learn from simplified models?
- What is the role of feedbacks through, for example, the soil-moisture and the ocean mixed-layer?
- Is machine learning a suitable tool to address these questions?
B) Organisation as a tool for model evaluation
- What are suitable diagnostics for evaluating organisation in models (examples could be potential vorticity and its spatial structure, and measures of instability in the presence of shear)?
- What diagnostics are currently used for meso-scale meteorology?
- Can diagnostics of organisation be used to constrain climate sensitivity and extreme events?
C) Introducing organisation in climate models
- At what resolution is there a need for a below grid-scale representation of organised structures, including gravity waves, unresolved updraughts, cold pools and meso-scale circulations?
- Can we represent subgrid organisation in climate models in a crude manner, or do the details matter?
- How can we ensure such a representation is scale-adaptive and does not deteriorate simulations as resolution continues to increase?
Date: May 27-29 2020
Venue: Niels Bohr Institute, Blegdamsvej 17, 2100 Copenhagen, Denmark
Contact: Jan Härter, haerter@nbi.ku.dk
Submission of abstracts and posters is open until January 15, 2019
Registration fee: 150€
Researchers
Internal scientists
Name | Title | Phone | |
---|---|---|---|
Härter, Jan Olaf Mirko | Associate professor | +45 93 56 57 36 | |
Meyer, Bettina | Postdoc | +45 353-33921 |
External scientists
Navn | Titel | Telefon | |
---|---|---|---|
Faranak Tootoonchi | Ph.d. student (external) | +45 353-20566 | Uppsala University |
Peter Berg | Collaborator | External collaborator | |
Christian Højer Skjellerup | M.Sc. student | ||
Mikkel Svendsen | M.Sc. student | ||
Enrico Maria Fenoaltea | M.Sc. student |