Environmental Engineering Reference
In-Depth Information
3. Results and Analysis
Preliminary WRF output comparisons show small differences in mean absolute
error (MAE) at the 12 km grid resolution domain ( Fig. 2) with the WRF/NLCD
run slightly better in most of the eastern part of the domain but slightly worse in
the middle part where shrublands and grasslands dominate. Note that these differ-
ences are very small due, in part, to the soil moisture nudging scheme in the PX
LSM that minimizes biases in 2-m temperature and mixing ratio. Largest
difference between CMAQ outputs is in the bi-directional NH3 surface flux because
this is closely related to landuse, especially crops which results in a significant
difference in NH 3 air concentrations ( Fig. 2 right panel).
Ammonia Concentration Difference
NLCD - GLCC
0.004
0.002
0.000
-0.002
-0.004
ppm
-.3
-.2
-.10
0.0
.1
.2
0.3
Fig. 2. WRF and CMAQ comparisons. Difference in 15-day mean absolute error in 2-m
temperature for WRF/NLCD - WRF/GLCC (left) and difference in ammonia concentration at 20
UTC on August 20, 2006 for CMAQ/NLCD - CMAQ/GLCC (right)
4. Conclusions and Future Studies
The preliminary model results from WRF and CMAQ with the new high resolution
land cover data are encouraging. We expect much greater improvement for higher
grid resolution model runs (4 and 1 km). We are also developing Biogenic Emission
Landcover Data version 4 (BELD4) land use data from 2001 30 m NLCD, 2001
1 km MODIS, USDA FIA data, and USDA National Agricultural Statistics (NASS)
crop data, which are planned to be the input to estimate biogenic emissions from
both the Model for Gaseous and Aerosols from Natural (MEGAN) sources and the
Biogenic Emission Inventory System (BEIS).
 
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