BrO in the Tropical and Subtropical UTLS

- Introduction BrO conundrum

- CU AMAX-DOAS (BrO, IO, NO2, H2O, O4)

& data status - Robustness of NO2 and

BrO VMR conversion- Comparison of VMRs

from remote-sensing with in-situ and model data

R. Volkamer, S. Baidar, B. Dix, T. Koenig, SY. Wang, J. Schmidt, D. Chen, G. Huey, D. Tanner, A. Weinheimer &

the TORERO and CONTRAST science teamsCU Boulder, Harvard, Georgia Tech, NCAR

TOREROJan/Feb 2012

CONTRASTJan/Feb 2014

BrO overview: observations and models

Theys et al. [2011]

Halogens deplete the O3 column by ~10% in the tropics (Saiz-Lopez et al., 2012)

Satellite: 1-3 x1013 molec cm-2

(Chance et al., 1998; Wagner et al., 2001; Richter et al., 2002; Van Roozendael et al., 2002; Theys et al., 2011)

Ground : 0.2-3 x1013 molec cm-2

(Schofield et al., 2004 , Hendrick et al., 2007; Theys et al., 2007; Coburn et al., 2011; Coburn et al., 2014, in prep.)

Balloon: 0.2-0.3 x1013 molec cm-2

(Pundt et al., 2002; Dorf et al., 2008)

Models: 0.2-1.0 x1013 molec cm-2

(~ 0.2-0.5 ppt)(Saiz Lopez et al., 2012; Parrella et al., 2012) – in the tropics

* 30 sec, ** 60 sec integration time

Passive remote sensing column observationsTrace gases and aerosols

CU-AMAX-DOAS instrument aboard NSF/NCAR GV

University of Colorado Airborne Multi-AXis Differential Optical Absorption Spectroscopy

Sun

elevation angle

height

concentration

solar zenith angle

Volkamer et al., 2009

spectrographs/detectors

Telescope pylon

motionstabilized

Sinreich et al., 2010, ACPCoburn et al., 2011, AMTBaidar et al., 2013, AMTDix et al., 2013, PNASOetjen et al., 2013, JGR

* 30 sec, ** 60 sec integration time

CU-AMAX-DOAS instrument aboard NSF/NCAR GVHardware: new telescope design implemented for CONTRASTSoftware: Autonomous deployment on the NSF/NCAR GV

zenith

nadir

limb

® Successful: more flexibility to record reference spectra® Successful: remote control in flight (RF07)® Primary benefit is added flexibility

CU-AMAX-DOAS data status- premise -

CU-AMAX-DOAS data status

Flight number

AMAX-DOAS data

Final dSCDs mixing ratios major/heavy clouds [%]

RF01 yes yes BrO 39.1RF02 partially yes BrO 17.5RF03 yes yes BrO 59.3RF04 yes yes BrO,IO,NO2 51.2

RF05 yes yes 68.6RF06 yes yes BrO 50.2RF07 yes yes 87.1RF08 no - - -RF09 yes yes 79.6RF10 yes yes 45.2RF11 yes yes 62.6RF12 partially yes 100RF13 yes yes 45.8RF14 yes yes 61.6RF15 yes yes BrO, IO, NO2 62.8

RF16 yes yes 70.5RF17 yes yes BrO,IO 13.8

BrO detection during CONTRAST (RF04)

0.1km 5.5km

13.1km

significant BrO detection above 8km

8.4km

BrO retrieval - robustness

stratospheric correction consistency between references

stratospheric contributions are reliably cancelled out consistent dSCD offset between different reference geometries

BrO retrieval - robustness

comparison with “Aliwell” settings sensitivity to HCHO cross section

BrO fit settings: 3-band analysis; BrO is conservatively bound Including/excluding HCHO has no effect on BrO dSCDs

RF15 NO2 – comparing column and in-situ vmr

very good agreement: RTM control Homogeneity

RF15 NO2 DOAS/CamCHEM

very good agreement: RTM control Homogeneity

RF04 BrO vertical profile

high DoFs; inversion is fully constrained by measurements observed BrO underestimated in upper FT by model

VCD(0.6±0.3) x1013 molec cm-2 0.2 x1013 molec cm-2

RF15 BrO DOAS/CIMS/CamCHEM along flight track

® DOAS and CIMS agree at theta(max)® DOAS BrO reproduces model gradients® observed BrO ~factor 2.5 higher in stratosphere and >2.5 outside

RF15 BrO: comparing DOAS & CamCHEM

® DOAS BrO follows model gradients but shows higher BrO, particularly in upper FT

TORERO BrO (unexplained BrO) – correlations

• Unexplained BrO in the upper tropical FT:– correlates with uFT exposure, decreasing H2O/O3 ratios (stratospheric tracer)– Is anti-correlated with aerosol SA– BrO in the lower stratosphere seems underestimated

4

3

2

1

0

B

rO (

pp

tv)

0.12 4 6

12 4 6

102

SA (m2 cm

-3)

0.0012 4 6

0.012 4 6

0.12 4 6

V (m3 cm

-3)

3 4 5 6 71

2 3 4 5 6 7

CO / O3 (ppbv ppbv-1

)0.1 1 10 100 1000

H2O / O3 (ppmv ppbv-1

)

100806040200

Upper FT exposure (%)

R2 = 0.87 R

2 = 0.87 R

2 = 0.31 R

2 = 0.91 R

2 = 0.80a b c d e

4

3

2

1

0

B

rO (

pp

tv)

0.001 0.01 0.1 1 10

SA (m2 cm

-3)

10-4

10-3

10-2

10-1

V (m3 cm

-3)

5 6 7 80.1

2 3 4 5 6 7

CO / O3 (ppbv ppbv-1

)0.01

2 4 60.1

2 4 61

2 4

H2O / O3 (ppmv ppbv-1

)

100806040200

Upper FT exposure (%)

RF04RF05 f g h i j

Tropospheric air

Lower stratospheric air

TORERO vertical profiles & comparison with models

GC4s: GEOS-4 Met + 25% Bry in LS (~1 pptv BrO); BM3: Box model with faster het. chemistry.

upper FT: sensitivity to dynamics and Bry in LSEAST: VCD [molec cm-2] NH/SH tropics: (1.5 ± 0.3) x1013 SH sub-tropics: (1.7 ± 0.3) x1013

SH mid-latitudes: (1.0 ± 0.3) x1013

West: VCD [molec cm-2] RF15: (0.6 ± 0.4) x1013 RF04: (0.6 ± 0.3) x1013

Conclusions• BrO is significantly detected above 6 km during RF04 and RF15.

– Retrievals are robust– NO2 shows RTM control and homogeneity for RF15

• Western Pacific: BrO in UT is lower than over the Eastern Pacific, but higher than predicted by models (Western and Eastern Pacific)– BrO VCD is 60% /12% lower than GOME-2, consistent with ground-based

MAX-DOAS data (Theys et al., 2011)– BrO in the lower stratosphere is higher than predicted

• Eastern Pacific: stratospheric sources are underestimated– Elevated BrO is sensitive to BrY in the LS (injected as bromocarbons over

Western Pacific?), and UTLS dynamics (GEOS4/GEOS5). – Stronger convection (GEOS4) leads to improvements in O3 profiles, and

invigorates UTLS transport• Comparison of RF01/RF17 BrO with ground based MAX-DOAS at MLO

presented at AGU 2014

Funding: NSF-CAREER award, NSF-AGS (CONTRAST/TORERO)Acknowledgements: NCAR/EOL, RAF, CONTRAST and TORERO teams

Confirmation of excellent motion control

20

15

10

5

0

Alti

tud

e [k

m]

806040200

Relative Error (%)5x10

4343210

O4 scd [molecule2cm

-5]

EA 0.35 EA -0.35 EA 1 EA -1 EA 2 EA -2

0.4

0.3

0.2

0.1

0.0

Pro

bab

ility

-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 Elevation Angle

1.0

0.8

0.6

0.4

0.2

0.0

Cu

mu

lative den

sity

N = 2262

1σ ~ 0.2O

Þ O4 observations in a Rayleigh atmosphere & GV C-migit sensorÞ Trace gases and aerosol extinction profiles

Technological innovation:Motion stabilization & low RMS

Baidar et al., 2013 AMT Dix et al., 2013 PNAS

20

15

10

5

020

15

10

5

020

15

10

5

0Alt

itu

de

(km

)

20

15

10

5

020

15

10

5

080400

BrOBox-AMF (350 nm)

12080400IO

Box-AMF (440 nm)

a b

e f

i j

m n

q r

RF01

RF04

RF05

RF12

RF14

12

8

4

012

8

4

012

8

4

0

Alt

itu

de

(km

)

12

8

4

012

8

4

00.80.60.40.20.0

BrOAveraging kernel

1.00.80.60.40.20.0IO

Averaging kernel

DoF = 12.9DoF = 17.8

DoF = 22.2 DoF = 22.8

DoF = 19.3 DoF = 19.8

DoF = 12.7 DoF = 14.0

DoF = 12.5 DoF = 14.0

c d

g h

k l

o p

s t

Robustness of the BrO dSCD retrievals

• References: consistent dSCD offset between different geometries• MBL limb, zenith, -10EA reference contain variable amount of Ring• BrO in MBL: no evidence in our spectra (upper limit ~ 0.5 pptv)• BrO fit settings: 3-band analysis; BrO is conservatively bound• Including/excluding HCHO has no effect on BrO dSCDs

15

10

5

0

-5

BrO

dS

CD

(101

3 m

ole

c cm

-2)

1614121086420

BrO dSCD - limb reference (1013

molec cm-2

)

Measurements:

RF05 EA-10 ref ( )RF12 EA-10 ref ( )RF12 Zenith ref ( )

b

RTM:

zenith w/ 0.0 pptv BrO in MBL zenith w/ 0.5 pptv BrO in MBL zenith w/ 1.0 pptv BrO in MBL EA-10 w/ BrO profile in RF05 EA-10 w/ BrO profile in RF12

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0BrO

op

tica

l d

ensi

ty (

10-3

a.u

.)

14121086420

Altitude (km)

RF05

3-band analysis RMS BrO OD

Aliwell et al settings RMS BrO OD

c15

10

5

0

-5

BrO

dS

CD

- n

o H

CH

O

(101

3 m

ole

c cm

-2)

14121086420-2

BrO dSCD with HCHO (1013

molec cm-2

)

RF01RF04RF05RF12RF14

Slope Intercept R2

0.91±0.05 1.18±0.40 x1013

0.991

0.98±0.08 0.07±0.58 x1013

0.999

1.00±0.06 -0.14±0.38 x1013

0.999

0.98±0.09 -0.42±0.44 x1013

0.998

0.91±0.08 0.16±0.38 x1013

0.915

d

40

30

20

10

0

Alt

itu

de

(km

)

0.12 4 6 8

12 4 6 8

102

Box-AMF

RF12 EA-10 MBL Limb MBL Zenith

a

15

10

5

0

-5

BrO

dS

CD

(101

3 m

ole

c cm

-2)

1614121086420

BrO dSCD - limb reference (1013

molec cm-2

)

Measurements:

RF05 EA-10 ref ( )RF12 EA-10 ref ( )RF12 Zenith ref ( )

b

RTM:

zenith w/ 0.0 pptv BrO in MBL zenith w/ 0.5 pptv BrO in MBL zenith w/ 1.0 pptv BrO in MBL EA-10 w/ BrO profile in RF05 EA-10 w/ BrO profile in RF12

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0BrO

op

tica

l d

ensi

ty (

10-3

a.u

.)

14121086420

Altitude (km)

RF05

3-band analysis RMS BrO OD

Aliwell et al settings RMS BrO OD

c15

10

5

0

-5

BrO

dS

CD

- n

o H

CH

O

(101

3 m

ole

c cm

-2)

14121086420-2

BrO dSCD with HCHO (1013

molec cm-2

)

RF01RF04RF05RF12RF14

Slope Intercept R2

0.91±0.05 1.18±0.40 x1013

0.991

0.98±0.08 0.07±0.58 x1013

0.999

1.00±0.06 -0.14±0.38 x1013

0.999

0.98±0.09 -0.42±0.44 x1013

0.998

0.91±0.08 0.16±0.38 x1013

0.915

d

40

30

20

10

0

Alt

itu

de

(km

)

0.12 4 6 8

12 4 6 8

102

Box-AMF

RF12 EA-10 MBL Limb MBL Zenith

a