P.L. Vidale*, M. Roberts +, L. Shaffrey*, W. Norton and J. Slingo * A. Clayton, M.-E. Demory, J. Donners, I. Stevens, D. Stevens *NCAS-Climate, Walker Institute, University of Reading, UK + UKMO Hadley Centre UJCC-HiGEM: what is in the treasure chest ?

Atmosphere-only integrations: the role of resolution 1 o - 1/3 o ocean model ∆x = 135 km∆x = 90 km ∆x = 60 km 1/3 o ocean model Flux coupler Completed in 2007 Matrix of AMIP2-SST forced integrations with increasing resolution: 25 yrs current climate, completed, climatologies at BADC: 1)Tropical cyclones (PLV) 2)Precipitation intensity and frequency, runoff (M-E Demory)  + Land surface processes (PLV+MED) 3)Mid-latitude storm tracks (Jen Catto, L. Shaffrey) 4)Blocking (MJR, J. Catto) 5)Dust and radiation M.W.) 25 yrs Delta-SST (+4K, -2K), completed, climatologies at BADC Tropical cyclones (PLV) In course: 25-yrs HiGEM-SST -> forcing N216 and N96 Planned in late 2008: Reynolds SSTs (0.25 deg., daily) -> forcing N216 and N96 Main results: < TCs more intense at higher resolution < Upper quantiles of precipitation appear at high resolution < Quality of runoff improves with resolution < Better Atlantic storm tracks at high-res. < Blocking at high-resolution ? < Changes in TC impacts in warmer world ?

Had-Hi-NUGAM, MIROC, ECHAM: 100 most intense Tropical Cyclones in 25 yrs HadGAM-HiGAM-NUGAM tangential wind Hurricane Mitch 850hPa 500hPa 200hPa 850hPa 500hPa 200hPa 850hPa 500hPa 200hPa 135km60kmresolution

Alpine precipitation in MAM

Coupled simulations in current climate 1 o - 1/3 o ocean model ∆x = 135 km∆x = 90 km ∆x = 60 km 1/3 o ocean model Flux coupler Completed in 2007 Matrix of coupled models, with increasing resolution (1.1 and 1.2 formulation): 1.Data: 2.Science TIWs in tropical Pacific: MJR (long-term impacts on climate), J.H. (nature of phenomenon) El Niño: MJR (process and teleconnections in ocean); E-T response to ENSO (UEA) SST bias improvement and its temporal evolution (D. Stevens) TCs (only recently started) MJO (in course) Mid-latitude storms (J.C. + L.S) Coastal upwelling (J.D.) Ocean-atmosphere coupling (D.S. + A.W. + MJR) Agulhas (S.S.) CTL-1.1CTL-1.2 N96-1deg100yrs70yrs N144-1/3deg130yrs70yrs N216-1/3deg~10yrs Cross-coupled55yrs

Main results from coupled work El Niño works in HiGEM ! (MJR draft paper) –Frequency characteristics, termination mechanism Wind stress curl - ocean mixing (DS + A. Dawson, MJR) –Origination mechanism ? TIWs (MJR, JH papers) –move heat meridionally –Ocean-Atmosphere interaction (JH, LS’s main paper) Pacific SSTs improved overall (why ?) Atmospheric variability: improved storm tracks in the Atlantic Wind stress curl and coastal upwelling (JD, DS) Improvements in Agulhas retroflection (SS, HC)

Sea surface height variability

Tropical instability waves Resolved in HiGEM, poorly resolved in HadGEM; Responsible for meridional heat transport in the tropical Pacific Invoked for explaining improved mean state in that region of the ocean, important for El Niño See papers by M. Roberts and J. Harle

Niño3 monthly anomaly spectra: dependence on resolution The low-resolution GCM shows max. power at the wrong frequency. Why ?

Climate change 1 o - 1/3 o ocean model ∆x = 135 km∆x = 90 km ∆x = 60 km 1/3 o ocean model Flux coupler Completed in 2007 Coupled HiGEM simulations with +2% CO2/year 1.Data: HiGEM1.1 transient currently reached 4xCO2 (~70yrs) Stabilised and run for 30 years at 2 and 4x CO2 (starting now) 2.Science: Ocean heat uptake What do tropical cyclones look like at 2-4x CO2 *** ? ENSO Sea-ice Precipitation extremes *** What happens in the upwelling regions ? Suppressed upwelling -> nutrient limitations -> biological deserts ? *** Require ensemble High and dry. The least biologically productive regions of the ocean -the subtropical gyres (darkest blue)- are getting bigger. Jeffrey Polovina of the U.S. National Marine Fisheries Service in Honolulu, GRL, 2008

Submitted proposals regarding HiGEM VOCALS (T. Toniazzo) Polar lows (K. Hodges) Decadal variability (Rowan Sutton’s NERC post-doc) NCEO: HiGEM-NUGEM model-to-satellite simulators (ISCCP-Calypso-CloudSat-EarthCARE), under the aegis of CFMIP-II; Exploring a consortium to study weather and climate extremes (with Edinburgh, Oxford)

Gaps in science WWBs -> ENSO Ocean heat uptake –mixed layer –overturning and heat transport Sea ice Precipitation excess, latent heat, radiation MJO Initialisation (ocean and sea-ice) Vertical mixing in the ocean (1.1 vs. 1.2) Regionalisation of impacts

The SST improvement mystery

Other activities Nature and impacts of tropical cyclones: –Multi-scale model intercomparison with Japanese groups (PLV, JS) –Development of TC proxies for low-res GCMs (JS, PLV) –Willis cat modelling (J. Strachan) Ocean Physics developments (Ian Stevens) 1%/yr CO2 transient simulation ? SSTs and Indian monsoon teleconnections in N216 AMIP (G. Martin) NAO in HiGEM_1.1 (A. Scaife, S. Keeley) Seasonal prediction (S. Keeley) Coupling of tropical convection and precip (G. Yang) MJO (P. Inness)

Outlook for HiGEM1-NUGEM We will need to base decisions on: –UJCC+HiGEM science –HadGEM3 configuration –Practice in other climate modelling groups –HECToR / Earth Simulator 2 / Reading BG resources Building HiGEM2 Priority areas: –Ocean-atmosphere (e.g. TC-ocean interaction) –Climate change –Ensembles –Regionalisation of impacts

Progression of UK Climate Models J. Slingo/PLV Atmospheric component resolution costs: physics costs not included Resolution increase = more CPU / shorter simulation COUPLED MODELSHadCM HadCM HadGEM HiGEM 2005 HadGEM HiGEM Atmosphere~300km 19 levels ~300km 19 levels ~135km 38 levels ~90km 38 levels ~90km 70 levels ~60km 70 levels Ocean2.5 0 x levels x levels 1 0 x 1 0 (1/3 0 ) 40 levels 1/3 0 x 1/ levels 1/2 0 x 1/ levels 1/4 0 x 1/ levels Flux Adjustment?YesNo Computing (excl. physics)1800 (excl. physics) 1000s years Runs on a PC 10s years Requires major supercomputer ∆x = 135 km∆x = 90 km∆x = 60 km∆x = 270 km UKMO NWP resolution until end of 2006 Model built for Earth Simulator work

What is the role of resolution in climate research ? 1 o - 1/3 o ocean model ∆x = 135 km∆x = 90 km ∆x = 60 km 1/3 o ocean model Flux coupler Completed in 2007 Matrix of coupled models, with increasing resolution: 1.What is the impact of resolving eddies in the ocean ? 2.What is the impact of resolving weather ? 3.What are the crucial scales for proper coupling ? 4.What are the emerging processes ? Vertical resolution is fixed: 38 atmospheric levels, 40 oceanic levels Hundreds of years of simulation have been completed on L-H experiments, including AMIP2

Tropical cyclones