weekend effect research
DESCRIPTION
Weekend Effect Research. Ozone Precursor Trends (Chapter 5.2) April 13, 2000. Ozone Precursor Trends. Objectives of trend analysis: ID response of ozone to precursor changes ID spatial & temporal changes ID changes in chemistry. Ozone Precursor Trends. Methodology: - PowerPoint PPT PresentationTRANSCRIPT
Weekend Effect Research
Ozone Precursor Trends(Chapter 5.2)
April 13, 2000
Ozone Precursor Trends
Objectives of trend analysis:
ID response of ozone to precursor changes
ID spatial & temporal changes
ID changes in chemistry
Ozone Precursor Trends
Methodology: hrly mean CO, NOX, NO, NO2, & O3, 1980-97
Day of Week (DOW) -- Tue-Thur = mid-week
averaged into 6 equal Periods of Day (POD)
running 3-year means
Ozone Precursor Trends
ID response of ozone to precursor change
SoCAB peak ozone has declined steadily
PM ozone declined in most areas of SoCAB
ozone decline for WDs appears WEs
Ozone Trends in SoCAB
0
10
20
30
40
50
60
70
80
90
Co
nce
ntr
ati
on
(p
ph
m)
19651967
19691971
19731975
19771979
19811983
19851987
19891991
19931995
1997
Year
Annual Maximum Mean of Top30 Days 3-year mean
Ozone Trends
Hawthorne, 1200-1600 PST
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997
Year
[O3
] in
pp
m
Sun3 Sat3 md-wk3 Sunday Saturday mid-week
Ozone Trends
Riverside-Rubidoux, 1200-1600 PST
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997
Year
[O3
] in
pp
m
Sun3 Sat3 md-wk3 Sunday Saturday mid-week
Ozone Precursor Trends
ID spatial & temporal changes
mid-day NOX trends generally similar by DOW
4-8 a.m. NOX trend often nearly flat in 1990s
O3 DOW “crossover” in late 1980s in eastern SoCAB
Ozone Precursor Trends
Los Angeles-N. Main, 1200-1600 PST
0.00
0.02
0.04
0.06
0.08
0.10
1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997
Year
[NO
x] i
n p
pm
Sun3 Sat3 md-wk3 Sunday Saturday mid-week
Ozone Precursor Trends
Hawthorne, 0400-0800 PST
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997
Year
[NO
x] i
n p
pm
Sun3 Sat3 md-wk3 Sunday Saturday mid-week
Ozone Trends
Upland, 1200-1600 PST
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997
Year
[O3
] in
pp
m
Sun3 Sat3 md-wk3 Sunday Saturday mid-week
Ozone Precursor Trends
ID changes in chemistry:
mid-AM NOX trend often flat but late-AM & early-PM NOX & NO2 down in 1990s
NO2 trends by DOW match NOX trends by DOW at most sites - NO2/NOX constant by DOW during late-AM & early-PM
Ozone Precursor Trends
Riverside-Rubidoux, 0400-0800 PST
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997
Year
[NO
x] i
n p
pm
Sun3 Sat3 md-wk3 Sunday Saturday mid-week
Ozone Precursor Trends
Riverside-Rubidoux, 1200-1600 PST
0.00
0.01
0.02
0.03
0.04
0.05
1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997
Year
[NO
2]
in p
pm
Sun3 Sat3 md-wk3 Sunday Saturday mid-week
Ozone Precursor Trends
Initial Findings: peak ozone down irrespective of NOX trend
ozone WE Effect much greater in 1990s than earlier but no commensurately greater NOX WE Effect
DOW “crossover” (WE > WD) has now occurred at all sites in SoCAB
Ozone Precursor Trends
Recommendation:
Investigate cause of step-wise change in mid-day ozone concentrations around 1989 as it accounts for much of ozone improvement and seems stronger for WDs than WEs.