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CRC NARSTONortheast Modeling Study

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Work performed with Alpine Geophysics, STI, and PSU ... 36-km, 12-km, and 4-km nests. G:crca24CMAS_workshopCMAS_CRC_NARSTO.ppt ... – PowerPoint PPT presentation

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Title: CRC NARSTONortheast Modeling Study

1
CRC NARSTO-Northeast Modeling Study

Ralph E. Morris, Edward Tai, and Greg Yarwood
ENVIRON International Corporation
101 Rowland Way
Novato, California 94945
Models-3 Users Workshop hosted by CMAS
October 21-23, 2002
Research Triangle Park, North Carolina

2
Acknowledgements

Coordinating Research Council (CRC) Atmospheric
Impacts Committee (Brent Bailey, Coordinator)
Work performed with Alpine Geophysics, STI,
and PSU
NARSTO acknowledged for data collection and
analysis activities and comments
MM5 data provided by Nelson Seaman at PSU
NARSTO Data Analysis Study directed by Till
Stoekenius at ENVIRON

3
Purpose

Investigate sensitivity of photochemical grid
models to inputs and options using the extensive
July 1995 NARSTO-Northeast database
Photochemical Grid Model (CMAQ vs CAMx)
Meteorological Model (MM5 vs RAMS)
Level of FDDA in MM5
VOC and/or NOx Emission Reductions
Grid Resolution (12-km vs 4-km)
Chemical Mechanism (CB-IV vs SAPRC97)
Advection Solver (Bott vs PPM vs Smolarkiewicz)

4
Overview of Approach

Minimize any interpolation of met data
LCP grid for MM5 met PSP grid for RAMS met
MM5 run with 3 levels of FDDA
Analysis Nudging (AN) only
AN and Observation Nudging (ON)
AN, ON, and VAD nudging (FOBS)
CMAQ and CAMx sensitivity runs
36-km, 12-km, and 4-km nests

5
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6
Emissions Processed by EMS95
7
Difficulties Encountered/Lessons Learned

Emissions Numerous delays were encountered
waiting for the latest emissions that were not
substantially different from the draft values.
CMAQ QSSA Chemistry Solver QSSA chemistry solver
is slow, inaccurate, and may go unstable so
should not be used.
MAQSIP Modeling System STI had difficulties
getting MAQSIP to work which was believed to be
due to not using the MAQSIP version of MM5.
Layer 1 Vertical Diffusivities Both CMAQ (MCIP)
and CAMx (MM5CAMx) modeling systems were updated
during then study with a minimum layer 1 KV.

8
Ozone Hourly Time Series in NYC
SubdomainCAMx/MM5, CAMx/RAMS, CMAQ/MM5
9
Daily Maximum Ozone -- July 14, 1995
CAMx/MM5 CMAQ/MM5
CAMx/RAMS
10
Daily Maximum Ozone -- July 15, 1995
CAMx/MM5 CAMx/RAMS CMAQ/MM5
11
12-km vs 4-km Grids-- CMAQ July 14, 1995
12
12-km vs 4-km Grids -- CAMx July 14, 1995
13
12-km vs 4-km Grids -- CMAQ July 15, 1995
14
12-km vs 4-km -- CAMx July 15, 1995
15
Comments on Grid Resolution Sensitivity

July 12-14 CMAQ and CAMx 4-km ozone estimates
more like each other than their 12-km parent
4-km ozone estimates generally lower than 12-km
CMAQ 4-km ozone smoother due to KH inversely
proportional to grid spacing
July 15, 1995 very different response to 4-km
grid
MM5 4-km grid explicitly resolves convective
activity with downdrafts etc.
Many other desirable features in MM5 4-km fields

16
MM5 12-km vs 4-km Wind Field 07/15/95
17
Emission Reduction Sensitivity Tests

Investigate sensitivity of ozone responses to 50
NOx and/or 50 VOC anthropogenic emission
reductions
Photochemical model CMAQ vs. CAMx
Grid resolution 12-km vs. 4-km (NOx only)
Chemical mechanism CB-IV vs SAPRC97
Advection Solver Bott vs Smolarkiewicz
Low-level vs Elevated NOx
Design Value Scaling for Four NE Sites

18
50 Anthropogenic VOC Reduction
19
50 Anthropogenic NOx Reduction
20
Emission Reduction Sensitivity Conclusions

NOx reductions result in wide-spread decreases in
ozone except in urban cores where increases
sometimes occur
VOC reductions result in ozone reductions in
urban cores but little change elsewhere
CAMx/MM5 is more VOC sensitive than either
CMAQ/MM5 or CAMx/RAMS
SPARC97 chemistry is more VOC sensitive than
CB-IV
Use of a 4-km grid increases the NOx disbenefits
in CAMx/MM5 but has less effects in CMAQ/MM5

21
Overall Conclusions

QSSA chemistry solver is slow and inaccurate and
should not be used
Smolarkiewicz advection solver is overly
diffusive and should not be used
CMAQ horizontal diffusion coefficient
parameterization that is inversely proportional
to grid resolution negates many of the benefits
of high resolution grids
Meteorological modeling of convective activity
should be studied for air pollution modeling
Ozone Design Value scaling can be very different
using different models