CAM 4 Update The plan Phil Rasch What

CAM 4 Update • The plan Phil Rasch – What is happening over the next 2. 5 days – Review of progress over last year – What remains to be done before CAM 4 – Last minute tweaks to Agenda? Comments? Questions?

Agenda Outline • Tuesday PM & Wednesday joint with Chemistry and Climate WG • Tuesday PM – – Overview – Update on Aerosols/Clouds for CAM 4 – 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 CAM 3. 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 CAM 4 – 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 CCSM 3. 5) (DONE, predicted or prescribed fuctionality. now the preferred dataset, coupled 0. 5 x 0. 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, 1 st fully coupled simulations in place) • Complete the Assessment of Morrison/Gettelman microphysics (mostly • Revised gravity wave and orographic wave breaking formulations • Complete the Assessment of Hybrid Isentropic coordinates (Papers in DONE, papers submitted, indirect effects being assessed, coupling with UW scheme in process [some surprises]) (works, but not yet exploited) 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 CAM 4 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 • 20 m 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-T 85 is equivalent to FV-1. 0 x 1. 25 -EUL-T 42 is equivalent to FV-2. 0 x 2. 50 -EUL-T 21 is NOT equivalent to FV-4. 0 x 5. 0 Day 9 baroclinic wave test case Williamson (2007), submitted to TELLUS. Jablonowski and Williamson, Q. J. R. Meteorol. Soc. (20

EUL-T 31 is used for paleoclimate applications Is there a FV resolution resembling EUL-T 31? Day 9 baroclinic wave test case

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

Efficiency Standalone CAM (not idealized) • FV-2. 7 x 3. 3 is approximately 55% more expensive than EUL-T 31 • FV-2. 7 x 3. 3 is approximately 54% less expensive than FV 1. 9 x 2. 5. Settings FV-2. 7 x 3. 3 : dt = 30 min. (10 min. dynamics dt) FV-1. 9 x 2. 5 : dt = 30 min. (7. 5 min. dynamics dt) EUL-T 31 : 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 geoengineering • Starts around now • Contact me: Phil Rasch, <pjr at ucar. edu>, 303 -497 -1368