hox and no observations during intex-a - nasa obs/mod intex intex tracep pemtb • median...
Post on 14-Feb-2020
0 views
Embed Size (px)
TRANSCRIPT
HOx and NO Observations during INTEX-A
X. Ren J. Mao R. Long R. Lesher W. Brune Department of Meteorology
Pennsylvania State University
HOx and NO measurement techniques
• OH and HO2 measurements ATHOS — 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 measurements TEI 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 pptv HO2 0.1 pptv NO 50 ppt
0
5
10
15 A
LT P
(k m
) ALT P
0
0.2
0.4
0.6
O H
(p pt
v) OH obs
0
20
40
H O
2 (p
pt v) HO2 obs
12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 0
500
1000
N O
(p pt
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 1000 0
2
4
6
8
10
12
NO (pptv)
A LT
P (k
m )
NO obs NO obs median NO PSS median
0 1 2 3 0
2
4
6
8
10
12
NO obs / NO PSS
A LT
P (k
m )
The NO values between 2-6 km are around or below the NO detection limit (~50 pptv).
0 20 40 0
2
4
6
8
10
12
HO2
A lti
tu de
( km
) obs obs mod
0 1 2 3 HO2 obs/mod
INTEX INTEX TRACEP PEMTB
• 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 0.6 0
2
4
6
8
10
12
OH
A lti
tu de
( km
)
obs obs mod
0 1 2 3 OH obs/mod
INTEX INTEX TRACEP PEMTB
(pptv) (pptv)
50 100150 0
2
4
6
8
10
12
CO (ppbv)
A lti
tu de
( km
)
101 102 103 NOx (pptv)
50 100 O3 (ppbv)
0 50 100 150 0
2
4
6
8
10
12
HO2/OH
A lti
tu de
( km
)
obs obs mod
0 1 2 3 HO2/OH obs/mod
INTEX INTEX TRACEP PEMTB
• 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.
0.2
0.4
0.6
O H
obs obs mod
100 102 0
1
2
3
O H
o bs
/m od
NOx (pptv)
INTEX INTEX TRACEP PEMTB
20
40
H O
2
obs obs mod
100 102 0
1
2
3
H O
2 ob
s/ m
od
NOx (pptv)
INTEX INTEX TRACEP PEMTB
• 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.
HO2 versus (PHOx)1/2
0 2000 4000 6000 8000 0
2
4
6
8
10
12
14
sqrt [P(HOx)] (sqrt [cm -3 s-1])
H O
2 o bs
(x 10
8 c m
-3 )
• P(HOx) = L(HOx) ∝ [ HO2 ]2, so [ HO2 ] ∝ sqrt {P(HOx)}. • Much HO2 variance can be explained by P(HOx).
HOx observed & modeled comparisons
0.01 0.1 1 10 0.01
0.1
1
10
OH mod (pptv)
O H
o bs
( pp
tv )
median obs/calc =0.58 r2 = 0.64
1 10 100 1
10
100
HO2 mod (pptv)
H O
2 ob
s (p
pt v)
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
105 106 107 108 0
2
4
6
8
10
12
P(OH) (cm-3)
A LT
P (k
m )
POH POH median O1D+H2O Peroxides HO2+NO
104 106 108 0
2
4
6
8
10
12
L(OH) (cm-3)
A LT
P (k
m )
LOH LOH median OH+CO OH+NO2 OH+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
105 106 107 108 0
2
4
6
8
10
12
P(HO2) (cm-3)
A LT
P (k
m )
104 106 108 0
2
4
6
8
10
12
L(HO2) (cm-3)
A LT
P (k
m )
PHO2 PHO2 median OH+CO HCHO+hv OH+HCHO
LHO2 LHO2 median HO2+NO HO2+O3 HO2+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 10 0
2
4
6
8
10
12
P(O3) (ppb hr -1)
A LT
P (
km )
0.01 0.1 1 10 0
2
4
6
8
10
12
L(O3) (ppb hr -1)
A LT
P (k
m )
PO3 PO3 median PO2-HO2 PO3-RO2
LO3 LO3 median LO3-O
1D LO3-OH LO3-HO2
-0.5 0 0.5 1 1.5 0
2
4
6
8
10
12
P(O3), L(O3), P(O3)-L(O3) (ppb hr -1)
A LT
P (
km )
P(O3) L(O3) P(O3)-L(O3)
• 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.
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.
HOx and NO Observations during INTEX-A HO2 versus (PHOx)1/2 HOx observed & modeled comparisons Modeled OH production and loss Modeled HO2 production and loss O3 budget Science questions we hope to answer