Synoptic events during MOSAiC and their Forecast Reliability in the Troposphere-Stratosphere System


SynopSys exploits routine meteorological weather observations from the MOSAiC expedition, remote sensing data products, and meteorological forecast data to detect and characterize synoptic events in the Arctic and evaluate their influence on mid-latitudes. We implement a diagnostic framework that will advance our knowledge on dynamical processes in the coupled troposphere-stratosphere system. A particular focus lies in the evaluation of enhanced predictive capability through a synergistic and unique set of measurements in the Arctic and a better representation of physical processes in weather forecast models. As well documented, the Arctic region is undergoing rapid change in a warming climate. This has many implications for mid-latitude climate and consequently on the future social, economic, and political development in both regions. Improving weather forecast taking into account the coupling of the Artic and mid-latitudes is thus essential.


SynopSys is a collaborative project involving Alfred Wegener Institute, University of Bremen and Deutscher Wetterdienst. The collaboration enables a unique integration of specific expertise in Arctic research, data analysis, remote sensing and numerical weather prediction.

Alfred Wegener Institute

Alfred Wegener Institute

Unversity of Bremen

German Weather Service

Department Research and Development

Principal Investigator: Alexander Cress

Post Doc: NN


SynopSys is structured in four work packages. Each of them serves as a main objective of the project.

WP1 Synoptic events in a large-scale context

  • Detection and evaluation of events in measurements and forecast data

  • Assessment of forecast skill

  • Dedicated experiments with the ICON weather forecast system, e.g. data denial experiments

  • Exploring data driven methods

  • Extended analysis of events in reanalysis products reaching beyond the Arctic and the year of the MOSAiC expedition

WP2 Assessment of ozone data and study of troposphere-stratosphere interaction

  • Improvement and validation of remote-sensing ozone products

  • Analysis of interaction between stratosphere and troposphere

WP3 Analysis of processes and process understanding

  • Development of diagnostics based on potential vorticity

  • Process-based analysis of the interaction between troposphere and stratosphere in a synoptic context

  • High resolution process studies with the ICON model in limited area mode

  • Attribution of forecast errors to potential model improvements

WP4 Sensitivity and impact studies

  • Sensitivity experiments with improved parametrizations in the ICON model

  • Assessment of improved forecast capabilities and their impact


SynopSys members meet regularly to coordinate their progress and ideas. Here we list the past and future meetings of the whole consortium.

Kick-off Meeting


  • Get to know each other
  • Talks from each Partner
    • SynopSys overview, first look at events and potential process studies (Ralf)
    • Process understanding from high resolution regional modelling (Annette)
    • Experiences of data assimilation and model performance in the Arctic during YOPP (Alexander)
    • Potential of satellite ozone observations for studies of troposphere-stratosphere exchange on different spatial scales (Mark/Alexey)
  • Data management and data exchange
  • Upcoming milestones and reporting
  • Potential joint publications
  • Outreach activities

Group photo from online meeting

Next Meeting is planned for July/August, when all positions will be filled.


  • Overland, J. E., Ballinger, T. J., Cohen, J., Francis, J. A., Hanna, E., Jaiser, R., ... & Zhang, X. (2021). How do intermittency and simultaneous processes obfuscate the Arctic influence on midlatitude winter extreme weather events?. Environmental Research Letters.
  • Köhler, R., Handorf, D., Jaiser, R., Dethloff, K., Zängl, G., Majewski, D., & Rex, M. (2021). Improved Circulation in the Northern Hemisphere by Adjusting Gravity Wave Drag Parameterizations in Seasonal Experiments With ICON‐NWP. Earth and Space Science, 8(3), e2021EA001676.
  • Feng, W., Dhomse S. S., Arosio, C., Weber, M., Burrows, J. P., Santee, M. L. and Chipperfield, M. P.: Arctic ozone depletion in 2019/20: Roles of chemistry, dynamics and the Montreal Protocol, Geophys. Res. Lett., 48, e2020GL091911, doi:10.1029/2020GL091911, 2021.
  • Weber, M., Arosio, C., Feng, W., Dhomse, S., Chipperfield, M. P., Meier, A., Burrows, J. P., Eichmann, K.-U., Richter, A. and Rozanov, A.: The unusual stratospheric Arctic winter 2019/20: Chemical ozone loss from satellite observations and TOMCAT chemical transport model, J. Geophys. Res. Atmos., 126, e2020JD034386, doi:10.1029/2020JD034386, 2021.


SynopSys is funded by the Federal Ministry of Education and Research (BMBF) as a grant to advance the scientific exploitation of the MOSAiC expedition under the umbrella of “Mare:N − Coastal, Marine and Polar Research for Sustainability Research” in the framework “Research for Sustainability” (FONA3). The funding period started in November 2020 and ends in October 2024.


Dr. Ralf Jaiser
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research
Telegrafenberg A45
14473 Potsdam, Germany
+49 331 288-2167