CAM 4 Update Phil Rasch The plan – What is happening over the next 2.5 days – Review of progress over last year – What remains to be done before CAM4 – Last minute tweaks to Agenda? Comments? Questions?

Agenda Outline Agenda Outline Tuesday PM & Wednesday joint with Chemistry and Climate WG Tuesday PM – –Overview –Update on Aerosols/Clouds for CAM4 –Reception Wednesday AM –Aerosol/Clouds Applications –Radiation Wednesday PM –Convection

Agenda Outline – Pt II Thursday AM –WACCM –General Interest Presentations Thursday PM –General Interest Presentations –Updates From other WGs –General Discussion & Closing Friday AM –Extra-Terrestrial applications of CAM

April 2007 SSC - CAM 4 Update Phil Rasch Defined CAM3.5, an interim model for use in BGC development. – Revised deep convection 3 candidate schemes (Neale/Richter, Zhang, Wu/Zhang) ‏ extremely careful evaluation procedure developed Neale Richter scheme selected for 3.5, but this does not imply that it will be used in CAM4 – Change to location of call to cloud fraction calculation (better physical justification) ‏ – Freeze dried clouds

As of April 2007 SSC Next Steps (nearly in the bag) ‏ Move forward in aerosol formulation: – merger of CGD & ACD bulk aerosol formulation (these aerosols will be used for transient simulations with CCSM3.5) (DONE, predicted or prescribed fuctionality. now the preferred dataset, coupled 0.5x0.5 also done) – integrate with new microphysics & Ghan droplet activation( ‏ DONE) Complete the Assessment of UW PBL and Shallow convection schemes (mostly DONE, papers in prep, 1st fully coupled simulations in place) Complete the Assessment of Morrison/Gettelman microphysics (mostly DONE, papers submitted, indirect effects being assessed, coupling with UW scheme in process [some surprises]) Revised gravity wave and orographic wave breaking formulations (works, but not yet exploited) Complete the Assessment of Hybrid Isentropic coordinates (Papers in prep, On Hold)

(As of April 2007) Next Steps (likely changes, but final outcome uncertain ) ‏ Explore horizontal and vertical resolution sensitivities (need to increase level of interaction with the DOE effort) (working, time for more focus on vertical) Ghan aerosol formulation desirable, interim aerosol solution (by Rasch, Mahowald, Hess, Barth, Bond) is the backup (Progress, but not there yet) Radiation – AER RRTM (Progress, but not there yet) – Assessment of change in representation still taking place – new radiative transfer API in development – Connections with microphysics, aerosols – Sub-column generator – BUGSrad (current implementation not ready) – ??

(Comments following April 2007 SSC meeting) Next Steps (very uncertain) subgridscale water variability (Little Progress) – sub-column generator – radiation --> heating & photolysis – microphysics alternate deep convection schemes – Zhang? – Bretherton? – Emanuel?

Time Schedules First Milestone for CAM4 completion was Jan 2008 First delay --> March 2008 Second delay --> October 2008 Loss of Collins, Hack in the Climate Modeling Section (CMS). Peter Lauritzen (numerical methods expert) joins CMS from ASP Rasch starts Sabbatical March 2008 –BUT I WILL CONTINUE BEING ENGAGED! CMS Attempting to refill Collins’ Position Hack on leave. –No immediate opportunity to refill position Redirection of Software Engineering group resources

Unresolved issues PBL developments –Visit last summer by Svensson, Holtslag & Park to work with Rasch and Large on PBL –Improvements to UW scheme, & sfc exchange parameterizations –Revised Holtslag and Boville scheme Improved entrainment formulation for top of PBL 20m thick surface layer (31 layer model) Coupled simulation looks very interesting. Little improvement in standalone CAM, but interesting coupled simulations! Opportunity to choose the best of both schemes

Low resolution CAM -Preliminary results Peter Hjort Lauritzen NCAR

In idealized test cases (adiabatic baroclinic wave and aquaplanet) -EUL-T85 is equivalent to FV-1.0x1.25 -EUL-T42 is equivalent to FV-2.0x2.50 -EUL-T21 is NOT equivalent to FV-4.0x5.0 Williamson (2007), submitted to TELLUS. Day 9 baroclinic wave test case Jablonowski and Williamson, Q. J. R. Meteorol. Soc. (2006)

EUL-T31 is used for paleoclimate applications Is there a FV resolution resembling EUL-T31? Day 9 baroclinic wave test case

Aqua-planet simulations (Neale & Hoskins, 2000) SURFACE PRESSURE Meridional eddy statistics Zonal averages ZONAL SURFACE STRESS Global average

Efficiency Standalone CAM (not idealized) FV-2.7x3.3 is approximately 55% more expensive than EUL-T31 FV-2.7x3.3 is approximately 54% less expensive than FV1.9x2.5. Settings FV-2.7x3.3 : dt = 30 min. (10 min. dynamics dt) FV-1.9x2.5 : dt = 30 min. (7.5 min. dynamics dt) EUL-T31 : dt = 30 min. Default IO settings, 30 day run on one node on Bluevista

Phil Rasch Post-doc Advert I have an opening for a post-doc to work on two projects: –Mimicing domain averaged Cloud Resolving Model behavior using Statistical Learning Theory –Exploring Climate Change mitigation through geo- engineering Starts around now Contact me: Phil Rasch,,