THE GLOBAL MODELING INITIATIVE (GMI): PAST CURRENT AND FUTURE ACTIVITIES

1. THE GLOBAL MODELING INITIATIVE (GMI): PAST CURRENT AND FUTURE ACTIVITIES Jose M. Rodriguez RSMAS/MAC University of Miami Jrodriguez@rsmas.miami.edu

2. OUTLINE • Motivation and history of GMI • Model description/past and ongoing work • Future goals-Relationship to GEOS-CHEM

3. GENESIS OF GMI (I) • In 1994, NASA’s Atmospheric Effects of Radiation Program (AEAP) realized the need to utilize 3-D CTMs in the assessment of the impact of both subsonic (upper troposphere) and proposed supersonic (lower stratosphere) aircrafts. • Previous assessments with 2-D models had pointed out a fundamental difficulty: WHY DO MODELS WITH SIMILAR INPUTS YIELD DIFFERENT RESULTS? This was very difficult to diagnose with completely separate 2-D models. Several orders of magnitude harder with 3-D models. • Assessments are labor intensive, and would be even more for 3-D models. • True assessments would in principle require an understanding of model performance against observations.

4. GENESIS OF GMI (II) • Solution: Integrate a 3-D CTM with the following elements: • “Modular” structure: Capability to exchange different model components (for example, met. Fields, advection algorithm, chemical modules…) to examine impact of each model component. • Structure integrated maintained at “core” institution (LLNL until now). • Modules and diagnostics provided by members of a GMI Science Team • Assessments carried out at core institution. • Model analysis and results “certified” by Science Team. • Use of model by Science Team members. • An assessment model parallel to research models.

5. DEVELOPMENT OF EFFORT • “Stratospheric” version of model integrated for participation in Supersonic assessment (Kawa et al., 1999). • AEAP program cancelled by NASA Code R (Aeronautics) in 1999. • Model “dormant” until effort was transferred to Code Y (ACMAP) in 2001. • Science Team reconstituted in 2001. Continued work in the stratosphere and integration of tropospheric version. • “Core” institution changed to NASA/GSFC in April 2003. Susan Strahan Project Manager. Tom Clune directing computational efforts. (Larger core team at Goddard).

6. CURRENT GOALS OF GMI • Provide an assessment tool for NASA assessment commitments: aircraft, but also WMO, IPCC, air quality? • Understand and quantify uncertainty and variability in model assessment simulations through testing and diagnosing of algorithms in a common modeling framework, and comparison to observational database (Assessment science). • Testbed for specific algorithms and implications of observations. • Provide user support to Science Team members and community (simulations, diagnostics, use of model by Science Team members).

8. BRIEF MODEL DESCRIPTION/ACTIVITIES (I) • STRATOSPHERE • Use met. fields from GEOS-STRAT, MACCM3 and GISS-II’ from ground to stratopause (23 to 46 levels, depending on model. Degraded to 4x5 in CTM. • “Grading” of performance for above met. Fields in tracer simulations (Douglass et al., 1999) • Solver from Ramaroson (1993), tested against SMVGEAR. • “Consensus” stratospheric chemistry from Goddard, Livermore… • PSC mechanism from D. Considine (Considine et al., 2000). • Tested advection algorithms (SLT, Lin and Rood, SOM). Settled for Lin and Rood (Rotman et al., 2000). • Prescribed aerosols and water. • Supersonic assessment (Kawa et al., 1999; Kinnison et al., 2000). • Recent simulations of stratospheric ozone (2000-2030) with fvDAS and fvGCM (Douglass, Strahan, Considine, ms in preparation).

9. BRIEF MODEL DESCRIPTION/WORK (II) • TROPOSPHERE • Use same set of meteorological fields: GEOS-STRAT, MACCM3, GISS-II’. • SYNOZ and NODOZ (ie., SYNOZ for NOx). • Lightning source from Price (1990), modified by Pickering. • Emission inventories, dry/wet deposition, chemical mechanism from GEOS-CHEM. • Aerosols prescribed from LLNL model (Chuang) • Aerosols microphysics being integrated (Penner). Intercomparison of microphysical modules from Penner, Weisenstein (AER), and McGraw (Brookhaven). • Full-chemistry simulation for above 3 fields and 1996-1997 conditions. Evaluation of model performance (Logan). Comparison to GEOS-CHEM results (Logan, Rodriguez, Randall Martin). • Subsonic Assessment for UEET (Rodriguez).

10. FUTURE DIRECTIONS: SHORT TERM. • Transition to GSFC by end of summer. • Construction of GMI web site (gmi.gsfc.nasa.gov) • User support at GSFC. • Assessment of aircraft aerosol impact for UEET. • Hindcast of stratospheric ozone. • Further analysis of numerical issues in model (resolution, TPCORE versions). • Integration of coupled stratospheric-tropospheric model. • Continued validation of tropospheric model. • Evaluate uncertainties due to dry/wet depostion processes, boundary layer parameterization. • Upgrade of microphysics. • Dependence of O3 and aerosol radiative forcing on meteorological fields, other processes? (IPCC). • First indirect effect? (Aerosol-cloud interactions).

11. GMI AND GEOS-CHEM (OR OTHER MODELS). • GMI has profited from GEOS-CHEM research efforts (“research” model vs. “assessment” model). • Algorithms • Model evaluation (Logan) • Comparison of GMI and GEOS-CHEM results (Logan, Martin). • Emphasis on user support will hopefully help GEOS-CHEM efforts • Testbed capabilities • Expand research efforts • Understanding of model/version differences.