WGNE Systematic Errors Workshop: Grand and Other Challenges Christian Jakob, ARC Centre of Excellence for Climate System Science, Monash University, Melbourne, Australia

Challenges - The expectations Predict weather not just flowExtend the range of useful predictions Predict weather not just flow Support adaptation and mitigation decisions Courtesy of WMO Hurrell et al, BAMS 2009

The WCRP Grand Challenges ✤ Cryosphere in a Changing Climate ✤ Regional Climate Information ✤ Sea-Level Rise and Regional Impacts ✤ Clouds, Circulation and Climate Sensitivity ✤ Changes in Water Availability ✤ Science Underpinning the Prediction and Attribution of Extreme Events

The Common Challenge: ✤ Not a single one of these grand challenges an be met without models! ✤ All of them will require major improvements to models! ✤ Those improvements will need to be made in areas of long-standing systematic model errors! ✤ A MAJOR CHALLENGE: Diagnose, understand and ALLEVIATE key systematic model errors in support of all other challenges.

Challenges - An example No major breakthroughs from CMIP3 to CMIP5!

A survey on key model issues in 2010 concluded: > 130 responses, some by individuals, many by groups, most major centres are represented

✤ “Classic” physics problems (clouds, precipitation, land, ocean mixing, model biases, tropics, polar climate etc) dominate the key problem replies over more recent “headline” ESM issues such as carbon, aerosols etc. ✤ Lack of observations, poor interactions between communities and lack of suitable methods rank equal as the key obstacles. ✤ Better use of available resources (especially obs) and more integrated research teams rank first among the solutions just before new observations and better model experiments. Program structures (weather/climate, flexibility, new groups) rank next and well ahead of issues like resolution and computing. A survey on key model issues in 2010 concluded:

The climate change building Creative Commons

The model development house The Seventies and Eighties Atmosphere Land

Atmosphere Land Ocean and Sea Ice Aerosols The Eighties and Nineties The model development house

Atmosphere Land Ocean and Sea Ice Aerosols Carbon Chemistry Services Today Solution Strengthen the foundations of the existing house. The model development house

Model Overall assessment Find processes and phenomena of relevance Perform process studies (model + observations) Select suitable process studies Design model improvements Data community Model user/ evaluation community Model development community Application NWP; seasonal; climate Tuning (important but limited insight) Great insight but of potentially limited importance Model development is a community effort

My hopes for the workshop ✤ Identify key areas for model improvement. ✤ Discuss new diagnostic techniques in support of model applications and DEVELOPMENT. ✤ Bring weather and climate communities closer together. ✤ Bring model diagnosticians, observationalists and model developers closer together - Wednesday is Hug-a-model-developer day! ✤ Do good science and have fun!