simultaneous airborne measurements of bro, hobr, brcl and br 2 in the tropics: inorganic halogens...
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Simultaneous Airborne Measurements of BrO, HOBr, BrCl and Br2 in the Tropics: Inorganic Halogens and Subsequent O3
Depletion
Michael Le Breton, Jennifer Muller, Kimberley Leather, Thomas Bannan, Steve Andrews, Shallcross, Asan Bacak & Carl Percival
Outline
• Instrumental setup - CIMS
• Data coverage
• Data results
• Modelling vs measured
• SS O3 depletion
Data coverage
Flight duration CIMS data QCL data SP-2 Notes
B823 03:05 03:05 03:05 03:05 Data still needs to be worked upB824 03:17 03:17 03:17 03:17 QCL Calibration needs to be worked onB825 02:42 02:42 02:42 02:42B826 03:37 04:37 03:37 03:37
B827 03:13 04:13 03:13 03:13
B828 03:05 00:00 03:05 03:05 Power failure pre flight so no CIMSB829 03:20 04:20 03:20 03:20B830 04:23 05:23 04:23 04:23B831 04:10 05:10 04:10 04:10B832 03:45 04:45 03:45 03:45B833 04:00 04:00 04:00 04:00B834 04:00 04:00 04:00 04:00B835 02:00 02:00 02:00 02:00 QCL Calibration needs to be worked onB836 03:55 03:55 03:55 03:55 QCL Calibration needs to be worked on
B837 03:45 03:45 03:45 03:45
B838 02:20 00:00 02:20 02:20 Overheating has affected CIMS data - being worked onB839 03:49 00:00 03:49 03:49 Overheating has affected CIMS data - being worked onB840 04:00 04:00 04:00 04:00 QCL Calibration needs to be worked onB841 03:42 03:42 03:42 03:42B842 03:46 03:46 03:46 03:46B843 03:40 03:40 03:40 03:40B844 03:35 03:35 03:35 03:35B845 03:45 03:45 03:45 03:45B846 04:00 04:00 04:00 04:00
TOTAL 84:15 73:02 83:00 84:1510 minute segments of QCL flights lost where software crashed
% 100% 87% 96% 100%
Chemical Ionisation
A- + B B- + A
reagent ion
molecule to detect
I- + HCOOH → [HCOOH].I-
• Soft ionisation • High sensitivity
• Flexible ionization
• Detect both + and – ions
• ppt, LODs
CIMS measurements
101
102
103
104
105
106
Ion
co
un
ts H
z
300250200150100500x10
3
N2O5-
Br-
I- I
-.H2O
I-.HCl
I-.HCOOH
I-.HNO3
I-.ClNO2
I-.BrO I
-.HOBr I
-.BrCl
I-.Br2 (active bromine)
species seen as mass sensitivity (ion counts per ppt) LOD (ppt)
Formic acid I.HCOOH 173 35 25Nitric acid I.HNO3 190 25 36
Hydrogen chloride I.HCl 162 1.8 4Butanoic acid I.C3H7COOH 215 15 25
Nitrogen pentoxide NO3 62 27 1.9
Nitryl chloride I.ClNO2 208 34 33
Hydrogen cyanide I.HCN 154 33 0.4
Bromine monoxide I.BrO 222/224 16 0.8
Hypobromous acid I.HOBr.H2O 241 50 0.1
Bromine monochloride BrCl 113 50 0.1
Bromine I.Br2 287 100 0.1
I-.HOBr.H2OBrCl-
BrO calibration
NO HOBr , BrCl and Br2 all calibrated on FT
1. BrCl – Cl2 and Br2 gas mixture equilibrate
2. HOBr – AgNO3 (liberates Br)• Mix with CCl4 (Removes Br2)• Quantify with H+ and Br-
3. Br2 – gas mixture and perm tube
Time series example
1.0
0.9
0.8
0.7
0.6
0.5
[BrO
] p
pt
14:00 14:30 15:00 15:30 16:00 16:30
2.4
2.2
2.0
1.8
1.6
[Br2 ] p
pt
1.0
0.9
0.8
0.7
0.6
0.5
[BrC
l] p
pt
14:0013/02/2014
14:30 15:00 15:30 16:00 16:30
[BrCl] ppt
2.8
2.6
2.4
2.2
2.0
1.8
[HO
Br] p
pt
80
60
40
20
[O3]
pp
b6000
5000
4000
3000
2000
1000
Altitu
de
(me
tres
)
BrO Br2
BrCl HOBr O3
Altitude
B823 transit
8000600040002000
0
05:0019/01/2014
06:00 07:00 08:00
dat
80604020
1.5
1.0
0.5
0.0
500400300200100
0
30
20
10
0
altitude [ClNO2] [BrO] [N2O5] [O3]
local time in Kota Kinabalu/Palau
landed in Palau from KK
1.5
1.0
0.5
[BrO
]
80604020
[ClNO2]
8000
6000
4000
2000
altitu
de
size is time (bigger is further into flight)
11
10
9
8
lat
142140138136134132lon
size is alt
1.5
1.0
0.5
0.0
[BrO
] ppt
8000
6000
4000
2000
alti
tud
e (
me
tre
s)
1.51.00.5[BrO] ppt
3020100[ozone] ppb
BrO and O3 data
80
60
40
20
[O3]
pp
b
191817161514131211109876543210B823 B824 B825 B826 B828 B829 B830 B831 B832 B834 B835 B836 B837 B840 B841 B842 B843 B844 B845 B846
KKIA - PGUM
PGUM-TKK
PGUM-PGUM
TKK-TKK
PTRO-PTRO
PGUM-PTRO
TKK-TKK
PTRO-PTRO
PTRO-PGUM
PGUM-PGUM
PGUM-TKK
TKK-TKK
TKK-PGUM
PGUM-PTRO
PTRO-PTRO
PTRO-PGUMPGUM-PGUM PGUM-PGUM PGUM-PGUM
PGUM-PTRO
KKIA - Kota KinabaluPGUM - GuamTKK- ChuukPTRO - Palau
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
[BrO
] pp
t
191817161514131211109876543210Flight number
B823 B824 B825 B826 B827 B829 B830 B831 B832 B834 B835 B836 B837 B840 B841 B842 B843 B844 B845 B846
KKIA - PGUM
PGUM-PGUM
PGUM-TKK TKK-TKK
TKK-TKK
PGUM-PTRO
PTRO-PTRO
PTRO-PTRO PTRO-PGUM
PGUM-PGUM
PGUM-TKK
TKK-TKK
TKK-PGUM
PGUM-PTRO PTRO-PTRO
PTRO-PGUM
PGUM-PGUM
PGUM-PGUM
PGUM-PGUM
PGUM-PTRO
KKIA - Kota KinabaluPGUM - GuamTKK- ChuukPTRO - Palau
O3 loss reactions
1. Br + O3 → BrO + O3
2. Br + DMS → products
3. BrO + HO2 → HOBr
4. BrO + DMS → Br + DMSO
5. HOBr + hν → OH + Br
6. Br2 + hν → Br + Br
7. BrCl + hν → Br + Cl
8. HOBr (wet deposition)→
9. BrCl (wet deposition)→
10. Br2 (wet deposition)→
11. O3 + HO2 → OH + 2O2
12 O3 + hν → O(1D) + O2
13a O(1D) + N2 → O(3P) + N2
13b O(1D) + O2 → O(3P) + O2
13c O(1D) + H2O → OH + OH
14 BrO + CH3O2 → HOBr + CH2OO
15a CH2OO → OH + HO2
15b CH2OO + H2O → HCOOH + H2O
O3 loss reactions
Consider the four loss reactions
11. O3 + HO2 → OH + 2O2
16. O3 + OH → HO2 + O2
12 O3 + hν → O(1D) + O2
13c O(1D) + H2O → OH + OH
1. Br + O3 → BrO + O3
O3 HO2+O3 = k11[HO2][O3]
O3 OH+O3 = k16[OH][O3]
O3 Br+O3 = k1[Br][O3]
F1 =k13C[H2O] / k13a[N2] + k13b[O2] + k13C[H2O]
O3O1D = F1*J12[O3]
SS approx for HO2
We don’t know the wet deposition rate
underestimate of HO2 or lower limit.
[HO2] = J5 [HOBr] / K3[BrO] SS3
[HOBr] = k3[BrO][HO2] / J5 + J8] SS1
[HO2] = J5[HOBr] / K3[BrO] SS2
CIMS case studies
80604020
% loss of O3
6000
4000
2000Al
titud
e (m
etre
s)
O3 + OH
O3 + O1D
O3 + Br
O3 + HO2
Summary and further work
• A suite of inorganics simultaneously measured in tropics on aircraft
• Also have measurements of formic, butanoic, nitric, HCN, ClNO2 and N2O5
• CIMS measurements indicate model underestimates BrO by a factor of 3/4
• Other inorganic halogens underestimated by similar factor
• Free Br dominated by inorganic photolysis
• Inorganic halogen photolysis responsible for up to 20% O3 loss in TMBL