Starts 25 Jun 2018
Ends 6 Jul 2018
Central European Time
ICTP
Giambiagi Lecture Hall (AGH)
Strada Costiera, 11 I - 34151 Trieste (Italy)
The climate community is still faced with large uncertainties in estimating possible climate changes in the next decades and quantifying the relative role of anthropogenic contribution to climate change. Although most modern climate models are able to reproduce reasonably well global climatologies and patterns of interannual variations, they still struggle with pervasive biases and the representation of some of the climate phenomena involving the interaction and coupling between the atmosphere, the ocean and the cryosphere. The problem is compounded by the limited understanding of some of the physical mechanisms giving rise to both our present mean climate and its natural variability at different time scales. One possible way forward is the use of a hierarchy of models to tackle the most pressing questions in climate dynamics and modeling. Key among them, is whether the climate is stable, or whether internal feedbacks could lead to tipping points, abrupt changes, and transitions to fundamentally different equilibria. Changes in the oceanic overturning, ice-albedo effects, land-surface and vegetation coupling to the atmosphere, and radiative-convective properties of the atmosphere have all been suggested as possible causes of instability in the climate system. Advances in our understanding, quantification, and modelling of these processes are necessary both for the interpretation of the paleoclimate record and for the projection of possible future climate states. A variety of studies have found that multiple equilibria exist both in highly idealized and more comprehensive models of the climate system. Whether multiple equilibria do exist in state-of-the-art climate models is still a subject of controversy. A fundamental understanding of key processes within a hierarchical modeling framework will eventually translate into a better representation and simulation within state-of-the-art climate models, as it brings new insights for process-based evaluation of climate model reliability and fit for purpose. The use of hierarchies additionally promotes the use of standardized performance metrics and highlights instances when post-processing approaches (e.g. bias correction) or diverse model tuning practices should be explored. The school will be based on lectures on theoretical aspects of atmosphere, ocean and climate dynamics, with a focus on the present state of established knowledge and relevant mechanisms. The topic of the school, Multiple Equilibra in the Climate System, will be the subject of afternoon lectures, giving an overview of the most recent progress and hypotheses suggesting the existence of multiple equilibrium states, and consequences for past and future climates. Afternoons will also be devoted to practical sessions, involving the use of simplified climate models and analysis of relevant data sets. The school will be followed by the 2nd WCRP Grand Challenge Meeting on Monsoons and Tropical Rain Belts. Reliable projections of tropical rainfall changes are key to any climate adaption efforts in a warming world. Yet, our global climate models are a subpar tool for the task: their spatial resolution is too coarse to reproduce the deep convection that produces most rainfall in the tropics, and current parametrizations are inadequate – as signified by persistent biases in the simulation of the annual and diurnal cycles of rainfall in large areas of the oceans and continents, as well as the response to forcing of the past. Nonetheless, tropical rainfall is organized in the large-scale structures of the monsoons and the ITCZ whose dynamics are shaped by large-scale energetic and momentum constraints that involve the global circulation of both the ocean and the atmosphere. This suggests that building a coherent understanding of tropical rainfall can benefit from an understanding of these large-scale influences and their coupling with small scale cloud and precipitation processes. Making this link across scales to improve our understanding and our ability to anticipate future tropical rainfall changes is a key question in climate science. The workshop, building on the knowledge and practical skills acquired during the school, aims to bring together expertise on large-scale atmospheric and oceanic dynamics, small scale cloud and precipitation processes, hierarchical climate modeling and observation. The aim is to both review recent progress on tropical rainfall dynamics and to identify areas where progress is most amenable in the future given the existing and emerging modelling tools and theoretical frameworks. School speakers: Simona Bordoni, CalTech, USA David Ferreira, Reading U., UK In-Sik Kang, SNU, Republic of Korea John Marshall, MIT, USA Franco Molteni, ECMWF, UK Brian Rose, U. Albany, USA Geoff K. Vallis, U. Exeter, UK Shang-Ping Xie, SCRIPPS, USA Workshop speakers: William Boos, U.Cal Berkeley, USA Christian Jakob, Monash U., Australia Mahyar Mohtadi , Marum, Bremen, Germany Sonia Seneviratne, ETH Zürich, Switzerland Hui Su, JPL, USA Andrew Turner, U. Reading, UK Tianjun Zhou, IAP China
**DEADLINE: 01/03/2018**

Organizers

Fred Kucharski (ICTP), Anna Pirani (Universite' Paris-Saclay), Adrian Tompkins (ICTP), Michela Biasutti (Columbia University), Aiko Voigt (KIT), Local Organiser: Riccardo Farneti

Co-sponsors