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WRF-STILT: Progress Report

WRF-STILT: Progress Report. Jan 2007 Top-level slides provided by Janusz Eluszkiewicz and Thomas Nehrkorn Atmospheric & Environmental Research, Inc. 131 Hartwell Ave Lexington, Massachusetts 02421 www.aer.com. WRF-STILT Coupling: Current Tasks. Coupling of WRF with STILT

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WRF-STILT: Progress Report

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  1. WRF-STILT: Progress Report Jan 2007 Top-level slides provided by Janusz Eluszkiewicz and Thomas Nehrkorn Atmospheric & Environmental Research, Inc. 131 Hartwell Ave Lexington, Massachusetts 02421 www.aer.com

  2. WRF-STILT Coupling: Current Tasks • Coupling of WRF with STILT • Mapping of variables and data format conversions • Use of time-averaged momentum flux variables for improved mass conservation • Use of convective mass fluxes for vertical particle redistributions • Sensitivity testing and model evaluation • Sensitivity of trajectories and footprints to: • Treatment of convection • Model resolution • Effects of different Met Drivers (WRF, BRAMS, FNL…)

  3. WRF-STILT Coupling: Current Tasks • Sensitivity testing and model evaluation (cont) • Comparison of simulated and observed CO2 • Effect of met drivers (trajectories) on fit to observations • Effect of other inputs on fit to observations: • Computation of PBL height • Computation of radiative forcing • Vegetation type and other biosphere parameters • Evaluation of relative contributions of near- and far-field GEE, respiration, and other sources and sinks

  4. WRF-STILT Coupling: Future Tasks • Examine Role of Data Assimilation • WRF v2.2 supports analysis and observation nudging • +: Improved fit to observations • - : may degrade mass conservation of model solution • - : requires manual tuning of nudging parameters • WRF-4dvar (under development) provides a possible alternative • +: Analysis is a model solution, satisfies mass conservation • +: Tuning can be based on climatological or ensemble-based error statistics • - : requires significant personnel and computer resources • AER has experience in both approaches, has worked with NCAR on (MM5) 4dvar development

  5. WRF-STILT Coupling: Argyle Results • Obs exhibit nighttime spikes not reproduced by simulations • Sims exhibit occasional lows (< 340 ppm) • Common to WRF and BRAMS • NLDAS SWF tends to lower them further • Artificially replacing “mixed forest” with “deciduous” eliminates some lows

  6. WRF-STILT coupling: Argyle Results • The spike on July 4, 02Z caused by uptake in mixed forest - a case of extreme sensitivity to surface typing

  7. Footprints: WRF/Nested/BRAMS

  8. Water, ice, urban, other Grassland Cropland Savanna Shrubland Mixed Forest Deciduous Forest Subtropical evergreen Dry temperate evergreen Wet temperate evergreen Boreal evergreen

  9. SWF: WRF/Nested/BRAMS WRF40 may have hit a sunny spot, but… • BRAMS even sunnier • Replacing “mixed” with “deciduous” reduces uptake

  10. WRF/STILT Coupling: Reversibility • WRF dramatically improved over FNL. • BRAMS runs not practical (~ weeks to generate a comparable figure).

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