Observation Results

Model Comparisons Instantaneous Ozone Production and Loss

HOx Budget

A case Study on 5/29/2012 (OK Storm)

HOx Photochemistry during DC3Xinrong Ren1*, Jingqiu Mao2, Li Zhang3, David Miller3, William Brune3, and the DC3 science team

1NOAA-ARL and University of Maryland 2NOAA-GFDL and Princeton University 3Pennsylvania State University *Contact: Xinrong.Ren@noaa.gov

Experimental• Campaign: Deep Convective Clouds and Chemistry (DC3)• Location: Salina, Kasas• Period: May-June, 2012• Platform: DC-8• Instruments: Airborne Tropospheric Hydrogen Oxides Sensor (ATHOS)

for OH and HO2 detection based on laser-induced fluorescence (LIF), detection limits: OH = 0.01 pptv; HO2 = 0.1 pptv; uncertainty: ~±40% (2σ confidence).

Airborne OH Reactivity Instrument: 20-s time resolution; uncertainty: ~±1 s-1 (2σ confidence).

Platform: DC-8

Model CalculationsRACM2 photochemical box model (Goliff et al., AE, 2013)

constrained by observed data (DC8 1-min merged data Version R3) of O3, CO, NO, NO2, SO2, H2O2, VOCs (including alkanes, alkenes, aromatics, carbonyls, PAN and other organic nitrates), photolysis frequencies, T, P and humidity. Model output includes time series of OH, HO2, RO2, and other reactive intermediates.

Summary• OH, HO2, and OH reactivity were successfully measured on

the NASA DC-8 during DC3.• A box model based RACM2 was able to reproduce OH and

HO2 generally well, with a median observed-to-modeled ratio of 0.94 for OH and 1.02 for HO2, although the model tends to under-predict HO2 at low altitudes.

• No significant NO dependence in obs-to-mod OH and HO2ratios, although the model tends to slightly under-predict both OH and HO2 when NO levels were greater than 1 ppbv.

• Good agreement between the observed and calculated OH reactivity, with a median obs-to-calc ratio of 1.10. CO, NMHC, and OVOCs dominated OH reactivity.

• In an Oklahoma storm survey on May 29, 2012, the box model was able to simulate OH well but under-predicted HO2in inflow. Excellent agreement was obtained between observed and calculated OH reactivity.

• Main P(HOx) was O(1D)+H2O below 7 km and HCHO+hvabove 8 km. Main L(HOx) was HO2+HO2/RO2 below 10 km and OH + NOx above 10 km .

• A net O3 production of a few ppbv hr-1 below 2 km and above 10 km was observed.

AcknowledgementsThis work was supported by the NASA TCP. We thank theDC-8 management, crew, and support staff during the DC3preparation and deployment, Binh Tran for his help in the fielddeployment, and other participating groups for use of theirdata in this analysis.

Main P(HOx): O(1D) + H2O @ < 7 km HCHO+hv @ >8 kmMain L(HOx): HO2+HO2/RO2 @ < 10 km; OH + NOx @ > 10 km

• In general, measured OH and HO2 agree well with the model calculations within the combined measurement and model uncertainty.

• On average, the model tends to under-predict HO2 at low altitudes.

• No significant NO dependence in observed-to-modeled OH and HO2 ratios. The ratios are slightly less than unit when NO levels were greater than 1 ppbvindicating model over-prediction of OH and HO2.

• Compared to INTEX-A: OH ratio: similar @ 0-10km,

slightly < 1 @ >10km during DC3slightly > 1 @ >10km during INTEX-A

HO2 ratio: significantly > 1 @ >8km during INTEX-A>1 @ < 2km in both studies

• Relatively constant [OH] between 2-10 km and elevated [OH] above 10 km.• [HO2] decreases as altitude increases.• Higher OH and HO2 levels during INTEX-A (July 2004) than during DC3 (May-June, 2012) due to lower solar radiation during DC3, but similar HO2/OH ratios in the two studies.• OH reactivity (OHR): elevated in BL and generally low in the FT. Good agreement with a median obs-to-calc ratio of 1.10. CO, NMHC, and OVOCs are main OHR contributors.• Significant OHR (3-5 s-1) in some outflows was observed.

NASA DC-8

ATHOS inlet

Laser and electronics

0 0.2 0.4 0.6 0.80

2

4

6

8

10

12

OH (pptv)A

LTP

(km

)

0 10 20 30 40

HO2 (pptv)0 100 200 300

HO2/OH

DC3 1-minDC3 medianINTEX-A

Fig. 1 Instrumentation of ATHOS aboard the NASA DC-8.

Fig. 2 Vertical profiles of observed OH, HO2, and HO2/OH during DC3. For comparison, the same vertical profiles are plotted for flights out of the St. Louis area during INTEX-A.

108oW 102oW 96oW 90oW 84oW 78oW 30oN

33oN

36oN

39oN

42oN

0

20

40

60

[HO2] pptv

Fig. 3 Vertical profiles of observed and calculated OH reactivity during DC3. Pie chart shows the contributions to OHR from observed OH reactants.

Fig. 4 Flight track color-coated with HO2 mixing ratio during DC3.

0 1 2 3 4 50

2

4

6

8

10

12

[OH-obs]/[OH-mod]

ALTP

(km

)

0 1 2 3 4 5[HO2-obs]./[HO2-mod]

DC3 1-minDC3 medianINTEX-A

0 5 10 15 20 25 300

1

2

3

4

5

6

7

8

9

OH reactivity (s-1)

ALT

P (

km)

OHR calcOHR obsOHR obs medianOHR calc median

CO 27%

NOx 4%

NMHC 37%

OVOCs 19%

Others 13%

• Main P(O3): HO2+NO and RO2+NO

• Main L(O3): O3+HO2 and O(1D)+H2O

• Net P(O3): close to zero between 4-10km; a few ppb h-1 in UT/BL

10-2 10-1 100 1010

2

4

6

8

10

12

P(O3) (ppb hr-1)

ALT

P (

km)

PO3

PO3 median

PO3-HO2

PO3-RO2

10-2 10-1 100 1010

2

4

6

8

10

12

L(O3) (ppb hr-1)

LO3

LO3 median

LO3-O1D

LO3-OH

LO3-HO2

0 5 100

2

4

6

8

10

12

P(O3)-L(O3) (ppb hr-1)

104 105 106 1070

2

4

6

8

10

12

P(HOx) (cm-3 s-1)

ALTP

(km

)

PHOxPHOx medianO(1D)+H2OHCHO+hvH2O2+hv

103 104 105 106 1070

2

4

6

8

10

12

L(HOx) (cm-3 s-1)

LHOxLHOx medianHO2+HO2/RO2HO+HO2OH+NOx

0.01 0.1 1.00.01

0.1

1.0

OH mod (pptv)

OH

obs

(pp

tv)

median obs/calc =0.94r2 = 0.88

1 10 100 1

10

100

HO2 mod (pptv)

HO

2 obs

(pp

tv)

median obs/calc =1.02 r2 = 0.58

0.1

1

5

OH

obs

/mod

0.1

1

10

HO

2 obs

/mod

1 10 100 1000 100000.1

1

10

NO (pptv)

HO

2/OH

obs

/mod

0

0.2

0.4

[OH]obs pptv

[OH]mod pptv

0

20

40

[HO2]obs pptv

[HO2]mod pptv

0

5

10

OHR-obs s-1

OHR-mod s-1

0

50

100

150

[O3] ppbv

10

100

1000

10000

10

100

1000

10000

[HCHO] pptv[Isoprene] pptv

20:00 21:00 22:00 23:00 00:00 01:000

2

4

6x 10

-5

Time of May 29, 2013 (UTC)

J(O1D) s-1

[NO] pptv[NO2] pptvALTP m

Inflow Anvil

Abstract # A41B-0040