CRC Report No. A-34 - Coordinating Research Council
CRC Report No. A-34 - Coordinating Research Council
CRC Report No. A-34 - Coordinating Research Council
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April 2005<br />
receptors (Crestline and Lake Perris) stand out as having ambient contributions that are unrelated<br />
to the local emissions. This is because their local emissions are dominated by biogenic sources<br />
(> 65%) whereas the actual contribution of biogenics in the air is less than 10%. This is not due<br />
to chemical removal of biogenic VOCs because experiment 12 was designed to have no chemical<br />
degradation. The reason is that the air concentrations at the downwind receptors are dominated<br />
by transport of emissions (primarily the gasoline and background categories in experiment 12)<br />
from upwind locations. Other receptors show the same type of effects but smaller in magnitude.<br />
90<br />
Experiment 12<br />
Actual Contribution vs. Emissions Contribution<br />
12<br />
Anaheim<br />
80<br />
10<br />
Cr estline<br />
Di amond Bar<br />
Long Beach<br />
Van Nuys<br />
LAX<br />
Hawthor n<br />
8<br />
Lake Per r i s<br />
Actual Contribution (%)<br />
70<br />
60<br />
50<br />
40<br />
30<br />
6<br />
4<br />
2<br />
0<br />
Crestline<br />
Crestline<br />
Lake Perris<br />
Crestline<br />
Van Nuys<br />
Lake Per r i s<br />
Long Beach<br />
Lake Perris<br />
LAX<br />
LAX<br />
Hawthor n<br />
Long Beach<br />
Anahei m<br />
Di amond Bar Hawthor n<br />
Anahei m<br />
Lake Perris<br />
Van Nuys<br />
Crestline<br />
Long Beach<br />
Haw thorn<br />
Diamond Bar<br />
0 2 4 6 8 10 12<br />
Long Beach<br />
Van Nuys<br />
Diamond Bar<br />
Anaheim<br />
LAX<br />
Haw thorn<br />
Gasoline<br />
Diesel<br />
Solvent<br />
Biogenic<br />
Background<br />
CNG and Aged<br />
LPG<br />
1:1<br />
LAX<br />
20<br />
Diamond Bar<br />
Anaheim<br />
Anaheim<br />
10 Van Nuys<br />
Diamond Haw thorn Bar<br />
Crestline<br />
4.23<br />
Diamond Van<br />
Long<br />
Anaheim<br />
Nuys<br />
Beach<br />
Crestline Lake HawPerris<br />
thorn Bar<br />
Long AnaheimDiamond Beach Van Nuys Bar<br />
Lake Perris<br />
0<br />
0 10 20 30 40 50 60 70 80 90<br />
Emissions Contribution (%)<br />
Figure 4-11. Actual and emissions contributions in experiment 12 (with no chemical reactions)<br />
by receptor, averaged over all hours.<br />
The Hawthorn and LAX receptors provide an interesting comparison in Figure 4-11. These<br />
receptors are located in adjacent grid cells and have similar emissions contributions (Figure 4-<br />
10). The actual contributions at Hawthorn and LAX differ more than the emissions<br />
contributions, as seen from Figure 4-11 for the gasoline and background categories. This shows<br />
that averaging emissions over 9 grid cells (i.e., a 15-km square) centered on the receptor does not<br />
describe differences in air composition between LAX and Hawthorn. This discrepancy must be<br />
because the upwind footprint influencing the Hawthorn and LAX receptors is not a 15-km square<br />
around the receptor.<br />
Figure 4-12 compares the actual and emissions contributions in experiment 11, which is similar<br />
to experiment 12 but includes chemical decay. The patterns of deviation from a 1:1 relationship<br />
are very similar in Figures 4-12 and Figure 4-11. This shows that the main reason for actual<br />
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