Abstract
During the CalNex (California Research at the Nexus of Air Quality and Climate Change) field study in May-June 2010, measurements of volatile organic compounds (VOCs) were performed in the Los Angeles (LA) basin onboard a NOAA research aircraft and at a ground site located in Pasadena. A weekday-weekend effect in ozone, caused by lower NOx emissions due to reduced diesel truck traffic in the weekends, has been previously observed in Los Angeles and other cities. Measurements in the Caldecott tunnel show that emission ratios of VOCs do not vary with the day of the week, but measurements during CalNex2010 show a VOC weekday-weekend effect through faster photochemical processing at lower ambient NOx mixing ratios. Ambient VOC enhancement ratios of long-lived species such as benzene are the same between weekdays and weekends, whereas enhancement ratios of short-lived species, such as trimethyl benzene, are up to a factor of three lower on weekends. Based upon the observed differences in VOC enhancement ratios to CO, we determine that photochemical processing was on average 65%-75% faster on weekends during CalNex2010, which indicates that ambient OH radical concentrations were larger by this factor causing the observed change in VOC composition. A box model calculation based on the Master Chemical Mechanism was used to verify the increase in photochemical processing in the weekends. Key PointsSpatial and temporal photochemical processing in Los AngelesVOC weekday-weekend effectFaster photochemistry in weekends
| Original language | English (US) |
|---|---|
| Pages (from-to) | 5018-5028 |
| Number of pages | 11 |
| Journal | Journal of Geophysical Research C: Oceans |
| Volume | 118 |
| Issue number | 10 |
| DOIs | |
| State | Published - May 27 2013 |
Fingerprint
Keywords
- Faster photochemistry in weekends
- Spatial and temporal photochemical processing in Los Angeles
- VOC weekday-weekend effect
ASJC Scopus subject areas
- Atmospheric Science
- Geophysics
- Earth and Planetary Sciences (miscellaneous)
- Space and Planetary Science
Cite this
Photochemical aging of volatile organic compounds in the Los Angeles basin : Weekday-weekend effect. / Warneke, Carsten; De Gouw, Joost A.; Edwards, Peter M.; Holloway, John S.; Gilman, Jessica B.; Kuster, William C.; Graus, Martin; Atlas, Elliot L; Blake, Don; Gentner, Drew R.; Goldstein, Allen H.; Harley, Robert A.; Alvarez, Sergio; Rappenglueck, Bernhard; Trainer, Michael; Parrish, David D.
In: Journal of Geophysical Research C: Oceans, Vol. 118, No. 10, 27.05.2013, p. 5018-5028.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Photochemical aging of volatile organic compounds in the Los Angeles basin
T2 - Weekday-weekend effect
AU - Warneke, Carsten
AU - De Gouw, Joost A.
AU - Edwards, Peter M.
AU - Holloway, John S.
AU - Gilman, Jessica B.
AU - Kuster, William C.
AU - Graus, Martin
AU - Atlas, Elliot L
AU - Blake, Don
AU - Gentner, Drew R.
AU - Goldstein, Allen H.
AU - Harley, Robert A.
AU - Alvarez, Sergio
AU - Rappenglueck, Bernhard
AU - Trainer, Michael
AU - Parrish, David D.
PY - 2013/5/27
Y1 - 2013/5/27
N2 - During the CalNex (California Research at the Nexus of Air Quality and Climate Change) field study in May-June 2010, measurements of volatile organic compounds (VOCs) were performed in the Los Angeles (LA) basin onboard a NOAA research aircraft and at a ground site located in Pasadena. A weekday-weekend effect in ozone, caused by lower NOx emissions due to reduced diesel truck traffic in the weekends, has been previously observed in Los Angeles and other cities. Measurements in the Caldecott tunnel show that emission ratios of VOCs do not vary with the day of the week, but measurements during CalNex2010 show a VOC weekday-weekend effect through faster photochemical processing at lower ambient NOx mixing ratios. Ambient VOC enhancement ratios of long-lived species such as benzene are the same between weekdays and weekends, whereas enhancement ratios of short-lived species, such as trimethyl benzene, are up to a factor of three lower on weekends. Based upon the observed differences in VOC enhancement ratios to CO, we determine that photochemical processing was on average 65%-75% faster on weekends during CalNex2010, which indicates that ambient OH radical concentrations were larger by this factor causing the observed change in VOC composition. A box model calculation based on the Master Chemical Mechanism was used to verify the increase in photochemical processing in the weekends. Key PointsSpatial and temporal photochemical processing in Los AngelesVOC weekday-weekend effectFaster photochemistry in weekends
AB - During the CalNex (California Research at the Nexus of Air Quality and Climate Change) field study in May-June 2010, measurements of volatile organic compounds (VOCs) were performed in the Los Angeles (LA) basin onboard a NOAA research aircraft and at a ground site located in Pasadena. A weekday-weekend effect in ozone, caused by lower NOx emissions due to reduced diesel truck traffic in the weekends, has been previously observed in Los Angeles and other cities. Measurements in the Caldecott tunnel show that emission ratios of VOCs do not vary with the day of the week, but measurements during CalNex2010 show a VOC weekday-weekend effect through faster photochemical processing at lower ambient NOx mixing ratios. Ambient VOC enhancement ratios of long-lived species such as benzene are the same between weekdays and weekends, whereas enhancement ratios of short-lived species, such as trimethyl benzene, are up to a factor of three lower on weekends. Based upon the observed differences in VOC enhancement ratios to CO, we determine that photochemical processing was on average 65%-75% faster on weekends during CalNex2010, which indicates that ambient OH radical concentrations were larger by this factor causing the observed change in VOC composition. A box model calculation based on the Master Chemical Mechanism was used to verify the increase in photochemical processing in the weekends. Key PointsSpatial and temporal photochemical processing in Los AngelesVOC weekday-weekend effectFaster photochemistry in weekends
KW - Faster photochemistry in weekends
KW - Spatial and temporal photochemical processing in Los Angeles
KW - VOC weekday-weekend effect
UR - http://www.scopus.com/inward/record.url?scp=84881141870&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84881141870&partnerID=8YFLogxK
U2 - 10.1002/jgrd.50423
DO - 10.1002/jgrd.50423
M3 - Article
VL - 118
SP - 5018
EP - 5028
JO - Journal of Geophysical Research: Oceans
JF - Journal of Geophysical Research: Oceans
SN - 2169-9275
IS - 10
ER -