weekend effect hypotheses
DESCRIPTION
Weekend Effect Hypotheses. Air Resources Board Cal/EPA Leon Dolislager Air Pollution Research Specialist Atmospheric Processes Section. Weekend Effect. WE Effect Working Group. Purpose Investigation of cause(s) Coordination of research Sharing of results Web Page - www.arb.ca.gov/ - PowerPoint PPT PresentationTRANSCRIPT
Weekend Effect Hypotheses
Air Resources Board
Cal/EPA
Leon Dolislager
Air Pollution Research Specialist
Atmospheric Processes Section
0
30
60
90
120
150
180
210
Nu
mb
er
of
Da
ys
19651967
19691971
19731975
19771979
19811983
19851987
19891991
19931995
19971999
Year# of days when [O3] > 0.1945 ppm3-year moving average
STAGE 1 OZONE EPISODESSouth Coast Air Basin, 1965-2000
0.000
0.050
0.100
0.150
0.200
0.250
0.300
1980 1982 1984 1986 1988 1990 1992 1994 1996 1998
Year
Ozo
ne (
pp
m)
Weekday
Weekend
Major Emissions Source Region: L.A. - N. Main St.
0.000
0.050
0.100
0.150
0.200
0.250
0.300
1980 1982 1984 1986 1988 1990 1992 1994 1996 1998
Year
Ozo
ne
(p
pm
)
Weekday
Weekend
Downwind Receptor Region: Riverside
Weekend Effect
WE Effect Working Group Purpose
Investigation of cause(s) Coordination of research Sharing of results
Web Page - www.arb.ca.gov/ aqd/weekendeffect/
weekendeffect.html
Weekend vs. Control Strategy
Hypotheses of WE Effect NOX-reduction NOX-timing Carryover near the ground Carryover aloft Increased weekend emissions Decreased absorption of UV
sunlight
NOX-reduction
Fujita et al. 2000
a. O3 accumulation rate = [O3(max) - O3 (t NO=O3)]/(tO3max - t NO=O3)
Azusa, Summer 1995
0.00
0.04
0.08
0.12
0.16
0.20
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour (PDT)
O3
, N
O a
nd
NO
2*
(pp
m)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
CO
(p
pm
)
WE O3 WD O3 WE NO WD NO
WE NO2* WD NO2* WE CO WD CO
Carry Over O3, NO2, and PANHONO and HCHO NO, CO, and VOC
O3 Inhibition
(due to NO titration)
O3 Accumulat ion a
t = tO3max - tN O=O3
Post Maximum O3
Declining photolysis rate, increasing mixing and ventilation,
and titration of O3 by f resh NO emissions
CO
NO2
NO
O3
t NO=O3 on weekdays
t NO=O3 on weekends
2
NOX-reduction
Source: Adapted from Winner, Cass, and Harley (1995)as presented in Finlayson-Pitts and Pitts (2000), page 898.
NOX-timingFreeway traffic by day-of-week normalized to a midweek daily total of one
million vehicles; composite of 11 sub-regions of the South Coast Air Basin
0
10000
20000
30000
40000
50000
60000
70000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the Day
Tota
l Veh
icle
Co
un
t (p
er h
ou
r)
Sun Mon Tue-Thu Fri Sat
NOX-timingFreeway traffic by day-of-week expressed as percent of the midweek value;
composite of results for 11 sub-regions of the South Coast Air Basin
0%
20%
40%
60%
80%
100%
120%
140%
160%
180%
200%
220%
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the Day
Veh
icle
Co
un
t R
elat
ive
to M
idw
eek
Sun Mon Fri Sat
Carryover near groundCarbon monoxide profiles by day of week at Anaheim,
based on data for the May – October ozone seasons of 1996-1998.
0.000
0.200
0.400
0.600
0.800
1.000
1.200
1.400
1.600
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the Day
Mea
n C
arb
on
Mo
no
xid
e (p
pm
)
Sun Mon Tue-Thu Fri Sat
Carryover aloftUCD [O3] @ El Monte, 9/28/97
0
1000
2000
3000
4000
5000
6000
0 20 40 60 80 100 120 140 160 180 200
[Ozone] in ppb
Alt
itu
de
(fee
t M
SL
)
UCD a.m.
UCD a.m. (2)
UCD p.m.
UCD p.m. (2)
Increased WE emissions
Decreased UV absorption
Summary Plausible
NOX-reduction - likely NOX-timing - likely Carryover aloft Increased UV - unlikely Carryover at ground - unlikely
Not Plausible Increased emissions