Michael Prather (PI)
University of California Irvine
mprather@uci.edu

Development and Error Analysis of Key Model Components for GMI and GMAO

UC Irvine proposes a range of core developments and scientific studies directly with GMI that also support GMAO development.  The effort includes delivery of core modules and datasets (consistent with the ESMF), analysis of errors in these modules, and some specific scientific applications.  Over the next three years, GMI should lead the international community in quantifying the errors in CTM simulations for realistic case studies.  The ability to simulate atmospheric composition accurately (or at least to quantify one's errors) is critical to both GMAO and GMI, and it is expected that the UCI development and evaluation of specific modules related to chemistry, radiation and transport will contribute to this accomplishment.  As part of a GMI study to quantify the difference between the GMI and UCI CTMs doing 'identical' simulations, UCI stumbled upon relatively large tracer-transport errors in one or both of the models.  UCI will continue to pursue the 'doubling to convergence' studies with both UCI and GMI CTMs, not only to quantify this one source of error in both CTMs but also provide a strategy for how best to evaluate similar sources of error associated with model resolution.  Depending on results from the error analysis, we intend to provide an ESMF-compliant UCI tracer-transport core model as a possible alternative GMI core. Photolytic rates are a cornerstone of GMI and any predictions of atmospheric composition.  UCI proposes to maintain up-to-date photolysis rates for the GMI model using fast-JX (developed at UCI); to identify alternative J-values to quantify uncertainties (e.g., through IPMMI studies, cross-sections, algorithms, etc.); and to define scientific studies to propagate such uncertainties and thus constrain errors due photolysis (e.g., coupled stratosphere and troposphere during Pinatubo). The GMAO thrusts require a solid core of chemistry-transport modeling in addition to traditional general circulation modeling.  The UCI efforts in GMI to evaluate errors in tracer transport and photolysis should impact GMAO development, and UCI will ensure that not only the analyses, but also the modules for tracer transport and photolysis are developed under the ESMF guidelines for use as alternative modules. Under current GMI support UCI has supplied the Oslo/EC met fields to GMI for the year-2000 comparison (i.e., different met fields meant to simulate the same time period).  These EC pieced-forecast met fields have done a stunning job of simulating tropospheric and stratospheric ozone during the TRACE-P mission and they are available at native T42L40 resolution for 1997, 2000, and 2001.  Following the GMI year-2000 study, UCI will work with U. Oslo to obtain a continuous set of such met fields from 1997 and to prepare them in a suitable GMI format.  UCI would like to revisit its TRACE-P analysis with GMI using the alternative met fields, and to develop an AURA simulation/analysis using Oslo/EC met fields for year 2005.  UCI began work on GMI primarily with support from NASA's ACMAP for its CTM science and  model development, and with small GMI support for directed GMI tasks.  UCI expects to reverse this arrangement when the current ACMAP grant expires.  Thus, the projected funding for years 2 and 3 assumes that GMI takes over the primary model development at UCI (e.g., fast-J, tracer error analysis) and that ACMAP renewed funding supports at best some focused atmospheric chemistry applications.

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