OThree Chemistry Modeling of the Sept ’00 CCOS Ozone Episode: Diagnostic Experiments—Round 2 Central California Ozone Study: Bi-Weekly Presentation 4 T. W. Tesche Dennis McNally 15 December 2003

OThree Chemistry CAMx Diagnostic Runs: Rounds 1-2 CAMx Diagnostic Runs: Rounds 1-2  Round 1 Diagnostic Sensitivity Runs (across-the-board scalar changes) [presented at 3 Dec ’03 Bi-Weekly Call]  Run B (interim base case)  Run Bn3 (anthropogenic NOx emissions increased by factor of 3)  Run Bv3 (anthropogenic VOC emissions increased by factor of 3)  Run Bn3v3 (anthro VOC & NOx emissions increased by factor of 3)  Round 2 Diagnostic Sensitivity Runs (across-the-board scalar changes) [new for 23 Dec ’03 Bi-Weekly Call]  Run Bnp3v3 (NOx decreased, VOC increased by factors of 3)  Run B No Dry Deposition (dry deposition zeroed-out)  Objectives  ‘Bounding’ simulations to assess model response (overall and in SJV) to precursor emissions and key process changes.  Pertinent emissions sensitivity and process change simulations performed in previous (e.g., SARMAP) and ongoing CCOS (e.g., Bay Area) modeling studies examined also.

OThree Chemistry CAMx4 Diagnostic Experiments: Round 2

OThree Chemistry 18 Sept ’00 Ozone Peaks in the SJV

OThree Chemistry 19 Sept ’00 Ozone Peaks in the SJV

OThree Chemistry 20 Sept ’00 Ozone Peaks in the SJV

OThree Chemistry Spatial Mean Ozone Time Series: SJV Domain Base B Sens Bn3: (NOx up x3)

OThree Chemistry Spatial Mean Ozone Time Series: SJV Domain Sens Bv3: (VOC up x3) Sens Bn3v3: (VOC, NOx up x3)

OThree Chemistry Spatial Mean Ozone Time Series: SJV Domain Sens Bnp3v3: (VOC up x 3, NOx down x3) Sens B No Dry Dep:

OThree Chemistry Hourly Ozone on 18 Sept ’00: 1500 PST Base B Max Obs: ppb Max Pred: 96.1 ppb

OThree Chemistry Hourly Ozone on 18 Sept ’00: 1500 PST Sens Bn3 Max Obs: ppb Max Pred: 93.3 ppb Anthropogenic NOx Emissions Increased by Factor of 3

OThree Chemistry Hourly Ozone on 18 Sept ’00: 1500 PST Sens Bv3 Max Obs: ppb Max Pred: ppb Anthropogenic VOC Emissions Increased by Factor of 3

OThree Chemistry Hourly Ozone on 18 Sept ’00: 1500 PST Sens Bn3v3 Max Obs: ppb Max Pred: ppb Anthropogenic NOx & VOC Emissions Increased by Factor of 3

OThree Chemistry Hourly Ozone on 18 Sept ’00: 1500 PST Base Bnp3v3 Max Obs: ppb Max Pred: ppb Anthropogenic NOx Decreased, VOCs Increased by Factors of 3

OThree Chemistry Hourly Ozone on 18 Sept ’00: 1500 PST Base B No Dry Dep Max Obs: ppb Max Pred: ppb Base B with Dry Deposition Set to Zero

OThree Chemistry Ozone Time Series: Parlier (045) Base B Sens Bn3: (NOx up x3)

OThree Chemistry Ozone Time Series: Parlier (045) Sens Bv3: (VOC up x3) Sens Bn3v3: (VOC, NOx up x3)

OThree Chemistry Ozone Time Series: Parlier (045) Sens Bpn3v3: (VOC up x3; NOx dn x3) Sens B No Dry Dep:

OThree Chemistry Ozone Time Series: Arvin (029) Base B Sens Bn3: (NOx up x3)

OThree Chemistry Ozone Time Series: Arvin (029) Sens Bv3: (VOC up x3) Sens Bn3v3: (VOC, NOx up x3)

OThree Chemistry Ozone Time Series: Arvin (029) Sens Bpn3v3: (VOC up x3; NOx dn x3) Sens B No Dry Dep:

OThree Chemistry Findings of Round 2 Diagnostic Runs  Runs are diagnostic only; not intended to imply California inventories possess factor of 3 systematic errors across all categories.  Scalar increases (by factor of 3) in anthropogenic VOC and/or NOx inventories yield much greater ozone changes compared with MM5 sensitivity experiments.  Factor of 3 increase in NOx emissions substantially degrades model performance in the SJV and across the 4 km domain.  Factor of 3 increase in VOC emissions improves model performance statistically and graphically in the SJV; improvements across the 4 km domain are less.

OThree Chemistry Findings (cont.)  Factor of 3 VOC & NOx increases do not yield significant model performance improvement  Factor of 3 increase in VOC and decrease in NOx systematically degrades model performance  Removal of dry deposition process systematically degrades model performance  Of all the runs performed thusfar in Rounds 1 and 2, the VOC x3 scaleup run (Bv3) offers the most insight into the potential reasons for the current systematic underprediction of ozone in the Sept ’00 episode; particular focus is being placed in the ongoing Process Analysis activities on the role of VOC emissions in producing ozone in the SJV.