HOx and NO Observations during INTEX-A - NASA · 2005-04-18 · HO x and NO measurement techniques...
Transcript of HOx and NO Observations during INTEX-A - NASA · 2005-04-18 · HO x and NO measurement techniques...
HOx and NO Observations during INTEX-A
X. Ren J. Mao R. Long R. Lesher W. BruneDepartment of Meteorology
Pennsylvania State University
HOx and NO measurement techniques
• OH and HO2 measurementsATHOS — Airborne Tropospheric Hydrogen Oxides
Sensor– Laser-induced fluorescence (LIF) detection of OH
– Chemically convert HO2 to OH by HO2+NO followed by the detection of OH with LIF
• NO measurementsTEI 42C NO-NOx analyzer
– Chemiluminescence– NO single mode– Online NO span and zero checks
Data Quality
• Data coverage:OH (1 min) - 97%HO2 (1 min) - 95%NO (1 min) - 89%
• Typical uncertainties: HOx ±32% (2σ)NO ±30% (2σ)
• Detection limits: OH 0.01 pptvHO2 0.1 pptvNO 50 ppt
0
5
10
15A
LTP
(km
) ALT P
0
0.2
0.4
0.6
OH
(ppt
v) OH obs
0
20
40
HO
2 (ppt
v) HO2 obs
12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:000
500
1000
NO
(ppt
v)
Hour (UTC)
NO obs
HOx and NO observations (July 22, Flight 11)
HO2 and OH have good precision – sub-minute resolution will be used to examine variability.
Observed & PSS NO vertical profiles
1 10 100 10000
2
4
6
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12
NO (pptv)
ALT
P (k
m)
NO obsNO obs medianNO PSS median
0 1 2 30
2
4
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NO obs / NO PSS
ALT
P (k
m)
The NO values between 2-6 km are around or below the NO detection limit (~50 pptv).
0 20 400
2
4
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12
HO2
Alti
tude
(km
) obsobsmod
0 1 2 3HO2 obs/mod
INTEXINTEXTRACEPPEMTB
• Median observed-to-modeled OH ~ 0.6 at all altitudes.• Median observed-to-modeled HO2 ~ 0.8 up to 8 km.• Behavior is similar to that in TRACE-P.• Large observed-to-modeled OH in PBL correlates to
isoprene (from Jim Crawford) as seen in forests.
0 0.2 0.4 0.60
2
4
6
8
10
12
OH
Alti
tude
(km
)
obsobsmod
0 1 2 3OH obs/mod
INTEXINTEXTRACEPPEMTB
(pptv) (pptv)
• NOx in INTEX-A is greater than in TRACE-P & PEM TB; CO and O3 are similar in INTEX-A & TRACE-P.
• Observed-to-modeled HO2/OH is close to 1 below 7 km, but exceeds 2 above ~9 km.
• HO2/OH deviations appear to be NOx related.
50 1001500
2
4
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10
12
CO (ppbv)
Alti
tude
(km
)
101 102 103
NOx (pptv)50 100
O3 (ppbv)0 50 100 150
0
2
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12
HO2/OH
Alti
tude
(km
)
obsobsmod
0 1 2 3HO2/OH obs/mod
INTEXINTEXTRACEPPEMTB
• Observed-to-modeled OH shows little NOx-dependence.• Observed-to-modeled HO2 grows for NOx > few 100 pptv.• INTEX-A and TRACE-P dependences on NOx are similar.• Observed-to-modeled HO2 < 1 for NOx < few 100 pptv &
> 1 for NOx > few 100 pptv is usually observed by us and a few others.
0.2
0.4
0.6
OH
obsobsmod
100 1020
1
2
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OH
obs
/mod
NOx (pptv)
INTEXINTEXTRACEPPEMTB
20
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HO
2
obsobsmod
100 1020
1
2
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HO
2 obs
/mod
NOx (pptv)
INTEXINTEXTRACEPPEMTB
HO2 versus (PHOx)1/2
• P(HOx) = L(HOx) ∝ [ HO2 ]2, so [ HO2 ] ∝ sqrt {P(HOx)}.• Much HO2 variance can be explained by P(HOx).
0 2000 4000 6000 80000
2
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sqrt [P(HOx)] (sqrt [cm-3 s-1])
HO
2 obs
(x10
8 cm
-3)
HOx observed & modeled comparisons
0.01 0.1 1 100.01
0.1
1
10
OH mod (pptv)
OH
obs
(pp
tv)
median obs/calc =0.58 r2 = 0.64
1 10 1001
10
100
HO2 mod (pptv)
HO
2 obs
(pp
tv)
median obs/calc =0.77 r2 = 0.65
• Solid line: 1:1; dashed lines: obs. uncertainty ±32%.• HOx comparison similar to that in TRACE-P.
Modeled OH production and loss
105 106 107 1080
2
4
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10
12
P(OH) (cm-3)
ALT
P (k
m)
POHPOH medianO1D+H2OPeroxidesHO2+NO
104 106 1080
2
4
6
8
10
12
L(OH) (cm-3)
ALT
P (k
m)
LOHLOH medianOH+COOH+NO2OH+HCHO
Main P(OH) is O1D+H2O (below 5 km) and HO2+NO (above 5 km).Main L(OH) is OH+CO/VOC.
Modeled HO2 production and loss
105 106 107 1080
2
4
6
8
10
12
P(HO2) (cm-3)
ALT
P (k
m)
104 106 1080
2
4
6
8
10
12
L(HO2) (cm-3)
ALT
P (k
m)
PHO2PHO2 medianOH+COHCHO+hvOH+HCHO
LHO2LHO2 medianHO2+NOHO2+O3HO2+RO2
Main P(HO2) is OH+CO. Main L(HO2) is HO2-RO2 self-reactions (below 5 km) & HO2+NO (above 5 km).
O3 budget
0.01 0.1 1 100
2
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P(O3) (ppb hr-1)
ALT
P (
km)
0.01 0.1 1 100
2
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12
L(O3) (ppb hr-1)
ALT
P (k
m)
PO3PO3 medianPO2-HO2PO3-RO2
LO3LO3 medianLO3-O1DLO3-OHLO3-HO2
• Main P(O3): HO2+NO.
• Main L(O3): O1D+H2O (< 5 km) & O3+HO2/OH (> 5 km).
• Net O3 loss at altitudes between 1 km and 5 km.
-0.5 0 0.5 1 1.50
2
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P(O3), L(O3), P(O3)-L(O3) (ppb hr-1)
ALT
P (
km)
P(O3)L(O3)P(O3)-L(O3)
Science questions we hope to answer • General comparisons between observed and modeled HOx
– Were previous observed-to-modeled anomalies also observed in INTEX-A? (e.g., NOx-dependence of observed-to-modeled HO2)
– Can the HOx heterogeneous effects (or lack thereof) be understood?
• High speed photochemistry – one-to-a-few seconds– What are the effects of scale on calculating P(O3) from HO2 & NO?
– Is HOx behavior understood in urban, forest-fire, and long-range regionally transported plumes?
• HOx behavior in the planetary boundary layer– What is the behavior of HOx and P(O3) and vertical distribution in the
boundary layer?– Is isoprene chemistry in forested regions adequately understood?
• Collaborations with many others on these & other questions.