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WCRP Grand Challenge on

Clouds, Circulation and Climate Sensitivity

Sandrine Bony & Bjorn Stevens, Schloss Ringberg, March 2014

http://www.wcrp-climate.org/index.php/gc-clouds

WCRP mission :

To promote and coordinate climate research at the international level

What WCRP is good at :

Facilitating the development of scientific networks and communities

(e.g. workshops, field experiments)

Coordinating and leveraging efforts

In practice :

Implemented through core projects and working groups

WCRP is us !

Momentum and ideas from the community (e.g. CMIP, satellite simulators)

Where WCRP could be more helpful :

Defining collective priorities

Maintaining focus on critical problems and facilitating cross-cutting research

→Grand Challenges

WCRP Grand Challenges :

High priority, exciting research areas that are critical for climate science,

that require international partnership and coordination, and for which targeted

research efforts are likely to lead to significant progress over the next 5-10 years.

Six WCRP Grand Challenges :

GCs are meant to be both highly specific and highly focused,

to tackle specific barriers preventing progress.

- Regional Climate Information

- Sea-level Rise and Regional Impacts

- Cryosphere in a Changing Climate

- Changes in Water Availability

- Prediction and attribution of extreme events

- Clouds, Circulation and Climate Sensitivity

An opportunity to :

1. promote exciting research on critical science problems

2. identify specific barriers, gaps, missing connections

3. articulate science questions

which are most exciting, important, opportune

+ would benefit from international coordination

4. leverage and strengthen existing activities

A good timing :

strong inter-connected community, observational and modeling opportunities,

scientific maturity (e.g. use of a model hierarchy)

As a community, let's take the chance to do something with it !

WCRP Grand Challenge onClouds, Circulation and Climate Sensitivity


A few starting thoughts...

White paper draft : http://www.wcrp-climate.org/index.php/gc-clouds

Contours of this Grand Challenge

.... posed here in very broad terms

.... the goal of this workshop is to sharpen and to articulate this Grand Challenge

around a few specific science questions



1. How do clouds affect climate sensitivity and hydrological sensitivity ?

2-4.5C

IPCC 2013

How to improve :

- Physical understanding of cloud feedbacks & drivers of hydrological changes

- Interpretation of model spread and of major model-data discrepancies

Can we better connect to :

- Observations / proxies of past climate changes

- Model development



2. How do clouds couple to the atmospheric circulation?

Arakawa (WMO, 1975) : “... the modelling of time

dependent clouds is perhaps the weakest aspect of

the existing general circulation models and may be

the most difficult task in constructing any reliable

climate model”

Have we overlooked this problem for too long?

New opportunities ? (e.g.CRMs over large domains)Do we have adequate observations ?Link to model development ?



3. How to interpret climate and climate change patterns ?

?

Knutti & Sedlaceck 2012

Can we physically explain the robust and non-robust patterns?

Interpretation in terms of circulation ?

Role of cloud processes in climate patternsand variability ?

Stevens & Bony 2013

CMIP5 aqua-planets



4. How can observations of the recent and longer past (proxies) help ?

Do we have adequate observations we need to tackle these science questions ?

If not, which ones do we need ?

Can we better link “ideas” or “physical understanding” to “data” ?



5. How to accelerate model development and improvement ?

Persistent biases in climate and NWP models :

- physical / dynamical interpretation ?

- role of cloud and convective processes ?

Can we foster model development by connecting it

more strongly to :

- understanding of how the climate system works

- observations and LES/CRM analysis

- exciting science questions

WCRP-WWRP survey


Three themes

+ B3. Educational component ?

Two cross-cutting approaches

Grand Challenge Coordination :Sandrine Bony (LMD/IPSL, France) and Bjorn Stevens (MPI, Germany)

A1. Climate Sensitivity (Temperature & Precipitation)

A2. Coupling Clouds To Circulation

A3. Changing Patterns

B1. Leveraging the Past Record

B2. Towards More Reliable Models

We propose to articulate this Grand Challenge

around five main initiatives


Grand Challenge Coordination :Sandrine Bony (LMD/IPSL, France) and Bjorn Stevens (MPI, Germany)

A1. Climate Sensitivity (Temperature & Precipitation)Steven Sherwood (UNSW, Australia) and Mark Webb (Met Office, UK)

A2. Coupling Clouds To CirculationDargan Frierson (U Washington, US) and Pier Siebesma (KNMI, Netherlands)

A3. Changing PatternsTed Shepherd (U Reading, UK) and Adam Sobel (Columbia U, US)

B1. Leveraging the Past RecordRobert Pincus (NOAA, US) and Masa Kageyama (LSCE/IPSL, France)

B2. Towards More Reliable ModelsChristian Jakob (Monash U, Australia) and Masahiro Watanabe (U Tokyo, Japan)

Enjoy the Workshop !

6 Grand Challenges for the next decade

wcrp grand challenge on clouds, circulation and climate ... › ... › gc_intro_bony.pdf · grand...

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