Title: MCIP2AERMOD: A Prototype Tool for Preparing Meteorological Inputs for AERMOD
1MCIP2AERMODA Prototype Tool for Preparing
Meteorological Inputs for AERMOD
- Neil Davis and Sarav Arunachalam
- Institute for the Environment
- University of North Carolina at Chapel Hill
- Roger Brode
- U.S. Environmental Protection Agency
- Presented at the
- 7th Annual Models-3 CMAS Users Conference
- October 6-8, 2008
2Motivation
- Meteorological fields are key inputs for air
quality modeling - NWS data typically used in AERMOD modeling have
some limitations - Observed sites may be far from source location,
espl. RAOB sites - Wind measurements at ASOS locations have large
number of calm measurements - Gridded meteorological models potentially helpful
- For Hybrid (combining regional and local-scale)
modeling, a consistent set of meteorology for
CMAQ and AERMOD simulations is desirable - Avoids inconsistent meteorological fields
confounding differences in AQM outputs - EPA is exploring utilizing gridded met data and
created MM5 AERMOD tool, which was helpful in
developing this tool - Using MCIP outputs helps using either MM5 or WRF
to drive AERMOD - No transition needed down the road
3FAA Modeling Approach
4Approach
- Created Fortran-based utility with EDSS/Models-3
I/O API library - Process 2002 MM5 simulations at 12-km through
MCIP 2.3 - Use grid cell containing AERMOD source region for
both surface and upper air fields - No interpolation is performed
- Make use of METCRO2D, METCRO3D, METDOT3D, and
GRIDDESC files from MCIP output - Use all available fields directly from MCIP
output as these are the values CMAQ will be using - Only calculate variables which are not in MCIP
output - Adjust for AERMOD time requirements (LST, some
parameters require noon LST values)
5Met Fields Directly from MCIP
- Sensible Heat Flux
- Surface Roughness Length
- Surface Friction Velocity
- Wind Speed / Direction
- Temperature
- Surface Pressure
- Cloud Fraction
- Monin Obukhov Length
- Convective Velocity Scale
- Convective Mixing Height
- Mechanical Mixing Height
- Notes
- Some massaging of these variables performed
- Maximum / minimum thresholds
- Units conversion
- Mechanical Mixing height is both used directly
and calculated - Calculated only for convective conditions
6Fields Calculated in MCIP2AERMOD
- Mechanical Mixing Height
- Relative Humidity
- Potential Temperature gradient above convective
mixing height (VPTG), or lapse rate above mixing
height - Bowen Ratio
- Albedo
7AERMOD Study Location
- Red Airport Location
- Blue NWS Surface Site
- Green RAOB Site
- T.F. Green Airport in Providence, Rhode Island
8Evaluation Simulations
- Developed AERMOD simulations for several
pollutants using both AERMET and MCIP2AERMOD
meteorological outputs - Benzene, Formaldehyde, Primary EC, PM2.5
- Will focus on PEC in this presentation
- Emissions inputs created using the FAA EDMS model
to provide hourly emissions estimates of aircraft
activity at airport - 2002 NWS values were processed through AERMET
with constant surface characteristics in time and
space - Midday Albedo 0.5
- Daytime Bowen ratio 1.0
- Surface Roughness 0.1
- Receptors were placed at the center of every
census tract within a 50-km radius as well as at
routine AQ monitor locations - Our evaluation will look at comparing both
meteorology fields as well as the AERMOD
concentrations from both simulations - Diurnal plots are calculated using averages of
annual data
9Evaluation of met. fields (1 of 4)
Surface Temperature
- Very high correlation between NWS and MCIP data
- Diurnal and monthly patterns match very well
- MCIP is slightly cooler overall
10Evaluation of met. fields (2 of 4)
Mechanical Mixing Height
- MCIP produces lower mixing heights at night than
NWS, but higher mixing heights in general - MCIP also produces higher mixing heights during
summer months - High correlation, but MCIP results seem to fall
into discrete bins
11Evaluation of met. fields (3 of 4)
Wind Speed
- Shows stronger winds with NWS data, both diurnal
and seasonal - NWS data is grouped into threshold values
- High correlation overall
12Evaluation of met. fields (4 of 4)
Wind Rose
- NWS has more calms
- MCIP has fewer high wind values
- Directionally MCIP shows more south westerly flow
13Meteorology comparison
- Good agreement across most variables
- Comparison of vertical data unavailable, due to
lack of data in the NWS simulation - AERMET only calculates the lowest level values
when onsite data is not included - Common meteorological parameters (i.e., Temp,
pressure, winds) show more agreement than other
parameters - MCIP precipitation and clouds show large
discrepancies compared to NWS values (not
presented here)
14Evaluation of AERMOD outputs for PEC (1 of 5)
- Only slight differences can be seen here
- Most perceivable changes occur away from the
airport, deceptive due to log scale
15Evaluation of AERMOD outputs for PEC (2 of 5)
Zoomed-in domain
- Significant changes in airport vicinity
- MCIP-based AERMOD shows higher concentrations
16Evaluation of AERMOD outputs for PEC (3 of 5)
Annual Average Absolute Difference
- Maximum change of 0.1 ug/m3
- Largest changes to the North of the airport
- MCIP shown to have larger concentrations
17Evaluation of AERMOD outputs for PEC (4 of 5)
Comparison of Monthly Means
- MCIP data always higher
- Largest differences in the winter months
18Evaluation of AERMOD outputs for PEC (5 of 5)
Additional comparisons
- NWS has more lower concentration values
- MCIP has higher maximum concentrations
- Median, 25th and 75th percentiles are similar
- Good correlation overall
19Discussion
- New prototype tool developed to use gridded
meteorology (from either MM5 or WRF) for AERMOD - Evaluation of tool performed for AERMOD study of
T.F. Green (Providence) airport emissions of
several pollutants - Comparison of meteorological fields showed
reasonable agreement for most variables - Only limited comparison of upper air data was
possible - MCIP2AERMOD meteorology lead to higher
concentrations throughout the domain for PEC - Despite magnitude differences, correlations were
high between model simulations - Evaluation of outputs for other pollutants showed
similar patterns - Evaluation of AERMOD outputs with RIDEM field
study at T.F. Green is ongoing
20Future Work
- Complete evaluation of AERMOD inputs and outputs
using RIDEM field study data for 2005 - Explore sensitivity of AERMOD to different
physics options in MM5 (or WRF) - Additional tests in MCIP2AERMOD
- Include only noon time Bowen ratio
- Investigate interpolation
- Allow user to override surface parameters
- Set AERMET surface fields to be closer in
agreement to the MCIP values and reevaluate - Develop hybrid calculations of CMAQ and AERMOD
using consistent meteorology
21Acknowledgments
This work was funded by the FAA, under Grant
No.03-C-NE-MIT, Amendment No. 027 (w/ UNC-CH
Subaward No. 5710002072) 06-C-NE-MIT,
Amendment No. 002 (w/ UNC-CH Subaward No.
5710002208) 07-C-NE-UNC, Amendment No.
001 The Local Air Quality project is managed by
Mohan Gupta.
Any opinions, findings, and conclusions or
recommendations expressed in this material are
those of the author(s) and do not necessarily
reflect the views of the FAA, NASA or Transport
Canada.