Model Simulation of tropospheric BrO
Xin Yang, J. Pyle and R. Cox
Center for Atmospheric ScienceUniversity of Cambridge
7-9 Oct. 2007. Frascati, Italy
Basic model information• Model: a 3D global chemical transport model, p-TOMCAT, with detailed
bromine chemistry [Yang et al., JGR, 2005].
• Br sources: 6 bromocarbons and sea salt from both open ocean and polar sea ice surface due to wind-driven production. A new size-dependent Br depletion factor for sea salt aerosols
• Br-Chemistry: adding 3 heterogeneous reactivations on aerosols, such as HBr+HOBr—Br2+H2O
• Forcing field: ECWMF reanalysis data (every 6hrs)
• Resolutions: T42 (2.8x2.8 degrees) x 31 vertical layers
• Simulation period: 1998
• Output frequency: 2hrs (to match GOME SZA for BrO)
HBr, HOBr, Br2
wet or dry deposition
Bromine chemical scheme in p-TOMCAT model
BrO
Br
BrONO2
HOBr
Br2
O3
NO, OH, RO2, BrO
NO2
HO2,RO2
HO2, RO2, HCHO, RCHO
hv
hv, OH
hv
hv
BrNO2
NO2 hv
hv
HBrOH
BrO
Br
hv
Cloud particles
HNO3
Sea salt aerosols
N2O5
Ocean, land, polar sea ice
CH3Br, CHBr3,CH2Br2, CH2BrCl,CHBr2Cl, CHBrCl2
OH hv
Ocean sea salt
~0.62 TgBr/yr
~1-2 TgBr/yr
Sea ice sea salt
Comparison with GOME in March
The upper figure is the simulated monthly mean (March) daytime (9am-3pm) tropospheric column BrO(×1013 molecules/cm2 ). The bottom figure is GOME BrO – trop+strat
Basically, the model captured the main feature of the GOME BrO in arctic with large level along Arctic coasts and over northern American (Good).
An exception is over Greenland sea where model see a big BrO but GOME did not (Good or bad?)
Satellite is less sensitive over open water?
In SH, its autumn tropospheric BrO is about 2 × 1013 molecules/cm2, about 2 times of NH autumn level (Good)
In the tropics, the lowest tropospheric BrO is 0.5 × 1013 molecules/cm2
Comparison with GOME in Sep.
• Basically, the model captured the main structure of the ring-like high BrO around Antarctic during SH spring. Good
• The simulated BrO in SH spring is higher than that in the NH spring. (Bad ?)
• If model problem: • 1) overestimated Br depletion
factor for seasalts • 2) not including humidity effect on
sea salt production
• If true: underestimated by satellite due to less ice cover in Southern Ocean
• • In NH, its autumn tropospheric
BrO is about 1 × 1013 molecules/cm2, which is only half of SH autumn level (Good).
Over Barrow
0
2
4
6
8
10
12
14
0 50 100 150 200 250 300 350
Julian Day
Ve
rtic
al c
ou
lum
n B
rO (
*1E
13
mo
lec
/cm
^2
)
GOM E BrO over Barrow
SNOW run BrO
SEA ICE run BrO
OCEAN run brO
no-HET run BrO40
50
60
70
80
90
100
0 200
J ulian day
y = 0.436x - 0.2225R2 = 0.2078
02468
10121416
0 5 10 15GOME BrO
SN
OW
run
BrO
In the NHOver Alert (82N, 62W)
0
1
2
3
4
5
6
7
8
9
10
0 30 60 90 120 150 180 210 240 270 300 330 360
Julian day
Co
lum
n B
rO
GOME
Model
40
50
60
70
80
90
100
0 50 100 150 200 250 300
Julian day
SZ
A
GOME
Model
y = 0.8548x - 1.9117
R2 = 0.3298
0
2
4
6
8
10
0 2 4 6 8 10
GOME
Mo
del
Over NyAlesund (79N, 12E)
0
2
4
6
8
10
12
14
16
0 30 60 90 120 150 180 210 240 270 300 330 360
Julian day
Col
umn
BrO
GOME
Model40
50
60
70
80
90
100
0 50 100 150 200 250 300
Julian day
SZ
A
GOME
Model
y = 1.1359x - 2.8656
R2 = 0.3558
0
2
4
6
8
10
12
14
16
0 2 4 6 8 10
GOME
Mo
del
Over Summit (72N,38W)
0
1
2
3
4
5
6
7
8
9
0 50 100 150 200 250 300 350
Julian day
Col
umn
BrO
GOME
Model
40
50
60
70
80
90
100
0 100 200 300 400
Julian day
SZ
A
GOME
Model
y = 0.3233x - 0.6274
R2 = 0.1812
0
1
2
3
4
5
6
0 2 4 6 8 10
GOME
Mo
de
l
Over Harestua (60N, 11E)
0
1
2
3
4
5
6
7
8
0 30 60 90 120 150 180 210 240 270 300 330 360
Julian day
Col
umn
BrO
GOME BrO
Model BrO
30
40
50
60
70
80
90
100
0 100 200 300
Julian day
SZ
A
GOME
Model
y = 0.5045x - 1.0852
R2 = 0.1709
0
2
4
6
8
0 2 4 6 8
GOME
Mo
del
Over Harestua (60N, 11E)
0
1
2
3
4
5
6
7
8
0 30 60 90 120 150 180 210 240 270 300 330 360
Julian day
Co
lum
n B
rO
GOME BrO
Model BrO
Comparison between ground-based UV-vis and modeled tropospheric and stratospheric BrO columns.
By Hendrick et al., ACP-2007-0224.
1998
In the SH
Over Neumayer (70S, 8W)
0
2
4
6
8
10
12
0 30 60 90 120 150 180 210 240 270 300 330 360
Julian day
Col
umn
BrO
GOME
Model40
50
60
70
80
90
0 100 200 300 400
Julian day
SZ
A
GOME
Model
y = 0.4275x + 0.8503
R2 = 0.0393
0
2
4
6
8
10
12
0 2 4 6 8 10
GOME
Mo
del
Over Arrival Height (78S, 170E)
0
2
4
6
8
10
12
14
16
0 30 60 90 120 150 180 210 240 270 300 330 360
Julian day
Col
umn
BrO
GOME
Model 40
50
60
70
80
90
0 100 200 300 400
Julian day
SZ
A
Series1
Series2
y = -0.7881x + 7.8051
R2 = 0.1024
0
2
4
6
8
10
12
14
16
0 2 4 6 8 10
GOME
Mo
del
Over Alert (82N, 62W)
0
1
2
3
4
5
6
7
8
9
10
0 30 60 90 120 150 180 210 240 270 300 330 360
Julian day
Co
lum
n B
rO
GOME
Model
Over NyAlesund (79N, 12E)
0
2
4
6
8
10
12
14
16
0 30 60 90 120 150 180 210 240 270 300 330 360
Julian day
Col
umn
BrO
GOME
Model
Over Summit (72N,38W)
0
1
2
3
4
5
6
7
8
9
0 50 100 150 200 250 300 350
Julian day
Co
lum
n B
rO
GOME
Model
Over Harestua (60N, 11E)
0
1
2
3
4
5
6
7
8
0 30 60 90 120 150 180 210 240 270 300 330 360
Julian day
Co
lum
n B
rO
GOME BrO
Model BrO
Over Neumayer (70S, 8W)
0
2
4
6
8
10
12
0 30 60 90 120 150 180 210 240 270 300 330 360
Julian day
Col
umn
BrO
GOME
Model
Over Arrival Height (78S, 170E)
0
2
4
6
8
10
12
14
16
0 30 60 90 120 150 180 210 240 270 300 330 360
Julian day
Co
lum
n B
rO
GOME
Model
Satellite can not see BrO explosions happened in early spring in the SH (?!)
This is consistent with ship measurement by Wagner et al., ACP, 2007
Zonal mean BrO (pptv)
O3 loss (%)
Possible further collaboration
We hope to work together with scientist in this fields to validate our model through more comparisons with derived-BrO data from both satellite and ground based measurements. These comparisons can be in short time scale, such as daily variation, or in long time scale, such as seasonal or year-to-year variation, even in long term trend.
We hope TEMIS to supply more satellite column BrO data on global scale for further comparison, especially over the sites where high BrO events frequently happen, such as coastal regions of Arctic, Hudson bay, in SH over Weddle Sea and Rose Sea.
We also hope observers to pay some attentions on the ‘potential high BrO plumes’ over regions where are open water in local spring. For example, over Greenland Sea and off the main ice sheet in the Southern Ocean.
Thanks
Invitation by TEMIS/SEA
EU project THALOZ
NCAS/NERC, UK
Ozone loss
0
10
20
30
40
50
60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90
Julian day
Co
nc
en
tra
tio
n/w
ind
sp
ee
d
960
970
980
990
1000
1010
1020
1030
1040
Pre
ss
ure
(h
pa
)
O3 (SNOW run, ppbv)O3 (SEA ICE run, ppbv)O3 (OCEAN run. ppbv)O3 (no-HET run, ppbv)BrO (SNOW run, pptv)Brx (SNOW run, pptv)Model 10m wind (m/s) Observed daily mean wind (m/s)Observed max. wind (m/s)Model surface pressure (hpa)
Vertical diffusion and emission effects on O3 loss
0
20
40
60
80
100
120
140
160
180
82 83 84 85 86 87 88 89 90
Julian day
Br
sp
ec
ies
co
nc
en
tra
tio
n (
pp
tv)
0
5
10
15
20
25
30
O3
co
nc
en
tra
tio
n (
pp
bv
)
BrOx (no diff. and no emission)
BrOx (no diff. but w ith 1/10 emission)
Brx (no diff. but w ith 1/10 emission)
O3 (SNOW run)
O3 (no diff. and no emission)
O3 (no diff. but with 1/10 emission)