Earth System Modeling at UCLA Applications and Further Developments

2. Earth System Modeling at UCLA Applications and Further Developments Carlos Roberto Mechoso Department of Atmospheric Sciences, University of California Los Angeles, USA Goal:Develop and apply to problems of climate change a model that describes the coupled global atmosphere - global ocean system, including chemical tracers. Each model component designed for high-performance parallel internal execution and as a Common Architecture Component (CCA), and integrated in NASA’s ESM Framework. www.atmos.ucla.edu/~mechoso/esm

3. Atmospheric General Circulation Model (AGCM) Atmospheric Chemical Tracer Model (ACTM) Data Broker Oceanic General Circulation Model (OGCM) Oceanic Chemical Tracer Model (OCTM) UCLA Earth System Model Stage 3 Model elements: • UCLA AGCM with upgraded PBL parameterization • LANL version of Parallel Ocean Program (POP) upgraded to hybrid vertical coordinates (HYPOP) • UCLA ACTM (which can include up to 64 species) • JPL Ocean Chemical Transport Model • MIT and MOM OGCMs as options

4. Stratocumulus clouds play key roles in the climate system. Global climate models have serious difficulties in simulating these clouds. ENSO simulations and predictions can be greatly improved by improving model performance with tropical stratocumulus decks.

5. UCLA AGCM v7.5 R. Terra, 2002

6. Diurnal Cycle in Amazonia 4:00pm In Amazonia during the monsoon season, rainfall peaks at around 2 pm and convection peaks a few hours later. 2:00pm

7. The model captures the early afternoon peak of precipitation over the continental areas with monsoon circulations

9. A particular event Events in 20 years Sea surface temperature at equator 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 Simulated Year 140 160 180 200 220 240 260 280 Longitude Below average Above average -1.50 -1.25 -1.00 -0.75 -0.50 -0.25 0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 The highly realistic ENSO produced by the coupled AGCM/OGCM was obtained through extensive model development and numerical experimentation allowed by the efficient model codes developed under this project. (Contour interval: 0.50C left, 0.250C right )

11. The First Comprehensive Picture of Chlorofluorocarbons in the Atmosphere National Aeronautics and Space Administration Earth Science Enterprise Thirty-five year long simula-tions with the UCLA ESM yielded a comprehensive 3-D picture of the evolution in the atmosphere of 20 million tons of chlorofluorocarbons (CFCs) released since 1965, and subsequent chemical reactions. By simulating the full stra-tosphere rather than just the lower stratosphere where most CFC break-up occurs, the results significantly narrow uncertain-ties in CFC lifetimes. Percent CFC-11 emissions rate for 1965–1996. The highest emissions cluster over major industrial areas in the eastern United States and western Europe. (M. Gupta, R. P. Turco, C. R. Mechoso, and J. A. Spahr, 2001, JGR - Atmospheres.)

12. CFC-12 Evolutions in Selected Locations Validation for the simulations came from a network of eight surface observation stations, including the five Advanced Global Atmospheric Gases Experiment (AGAGE) stations. The results typically differed by just a few percentage points from each station’s readings. After 1997, all simulations show decreases in CFC-12, while the data show continued increases.

13. Methodology for concurrent execution of ESM components Atmospheric surface fluxes that drive the ocean are produced by the model component known as AGCM/Physics; sea surface temperatures (SSTs) that drive the atmosphere are produced by the ocean model component known as OGCM/Baroclinic.

14. Coupling between ESM components • Data transfers between ESM components are handled by Data Brokers. • One type is a Centralized Data Broker (CDB), which assembles the entire data field from a producer on a single processor before sending it to consumers. • CDBs can introduce performance bottlenecks and have processor memory limitations. • In view of these considerations, we have developed the UCB/UCLA Distributed Data Broker.

15. Distributed Data Broker Function To handle distributed data exchanges between the ESM component. Major Tasks • Gather information from each model component (may have been decomposed into many subdomains running at different processors). • Convert data resolutions, units…, etc. andredistribute them to the needed model components. • Keep track of coupling sequence, such as how often AGCM needs sea surface temperature, and which processors have those information.

16. Distributed Data Broker (DDB)Components • Communications Library General communication routines to manage the data exchanges based on standard communication toolkits (PVM(current), MPI (proposed), etc). • Model Communications Library Callable routines for registering and exchanging information between model components. • Data Translation Library Routines for data regridding.

19. Reported Performance: 40 GFLOPS (2001)

20. UCLA ESM Component Structure UCLA ESM Application Component Coupler Component UCLA Atmospheric Model Component CCSM Coupler LANL Ocean Model Component UCLA Chemistry and Aerosol Model LANL Sea-Ice Model Component

21. Check-Point • Code optimization and parallelization completed to a level acceptable with (1) research objectives, (2) available computer resources. • Case studies completed that demonstrate good model performance. • Perceived need to “modularize” major model components in order to facilitate implementation of model upgrades designed both in house and at other development groups.

22. Earth System Modeling Application ESMF_AppComp Coupled atmosphere / ocean simulation driver ESMF_CplComp Coupler Component performs data transformations and transfers between atmosphere and ocean Components ESMF_GridComp ESMF_GridComp NCAR/LANL CCSM NCEP Forecast NCEP Forecast UCLA AGCM atmosphere MIT OGCM ocean

24. CCA ESM Prototype Palette Arena Run Atmos Produce Driver Driver Consume Ocean Ocean Atmos GO Run Ocean Run Atmos Atmos Atmos Driver Produce DDB DDB Consume DDB Process Set A Produce Run Ocean Consume Ocean GO Run Atmos Run Ocean Driver Produce Consume DDB Process Set B

25. Summary • An ESM (ocean-atmosphere dynamics and chemistry) has been developed for high performance computers. • The ESM includes a novel Distributed Data Broker, a flexible, high-level syntax for coupling components of multidisciplinary applications. • The ESM is been applied to ENSO predictability and the evolution of chemical tracers (CFCs, Rn) in the atmosphere. • The ESM code is been integrated in NASA’s ESM Framework. Model components are been designed as Common Architecture Components (CCA).