I L M AT I E T E E N L A I T O S
METEOROLOGISKA INSTITUTET
F I N N I S H M E T E O R O L O G I CA L I N S T I T U T E
Changes in HOx and NOy Species During Solar Proton Events:
Analysis and Parameterization
Pekka T. Verronen, Finnish Meteorological Institute, Earth Observation, Helsinki, Finland
Ralph Lehmann, Alfred Wegener Institute for Polar and Marine Research, Potsdam, Germany
Shuhui Wang, Michelle L. Santee, Gloria L. Manney, Jet Propulsion Laboratory, Pasadena, CA, USA
Contact: [email protected]
Abstract. In the middle atmosphere, enhanced ionization by precipitating particles leads to changes in minor neutral composition through ion chemistry. For example, nitrogen
and water vapor molecules are dissociated, and odd hydrogen (HOx = H + OH + HO2) and odd nitrogen (NOx = N + NO + NO2) species are produced. Increase in HOx and
NOx concentrations can then boost the catalytic reaction cycles that destroy ozone.
In this paper, we utilize the Sodankylä Ion and Neutral chemistry model (SIC), which combines ion and neutral chemistry for particle precipitation studies. Based on an
analysis of the SIC chemistry, we demonstrate how positive ion chemistry produces NOx and HOx, while negative ion chemistry redistributes NOy species by converting NOx
and N2O5 to HNO3 and NO3). Recent SIC results on OH and HNO3 during solar proton events are presented, including comparisons with satellite instruments. We put forward
an improved parameterization, which takes into account both positive and negative ion chemistry and can be used to model the effects of particle precipitation.
THE SIC MODEL
MODEL-SATELLITE COMPARISON
ION CHEMISTRY PARAMETERIZATION
Above: The production rates of, e.g., OH and HNO3 can be calculated from SIC model results considering production (P ) and loss
(L) processes. Below: Examples of P/Q number, NH, January, Q =
100 cm−3s−1.
Above: Aura satellite on orbit with Microwave Limb Sounder (MLS)
on board. Below: NH polar HNO3 from MLS. Note the increase
during the solar proton event (middle panel).
Above: SIC model input/output diagram. Below: part of the SIC
positive ion scheme, and two examples of reaction pathways leading to H, OH, and HNO3 production.
Below: SIC-MLS comparison of HNO3 at 80◦N/75◦W.
06−Dec−2006
09−Dec−2006
85
85
80
80
75
75
75
70
70
70
SIC
MLS
80
Altitude (km)
11−Dec−2006
85
−− 0.005
−− 0.010
−− 0.022
−− 0.046
65
65
65
60
60
60
55
55
55
50
50
50
45
45
45
40
−2
0
2
Mixing ratio (ppbv)
40
−2
4
0
2
Mixing ratio (ppbv)
−− 0.100
−− 0.147
−− 0.215
−− 0.316
−− 0.464
−− 0.681
−− 1.000
hPa
40
−2
4
0
2
Mixing ratio (ppbv)
4
Below: SIC-MLS comparison of OH in December 2006. Note the
good agreement in daytime. SIC overestimates OH at nighttime on
Days 8 and 15.
→
→
→
→
− ∆E)
10
x 10
MLS
SIC with SPE
SIC without SPE
8
6
4
2
0
05
→
→
→
→
OH at 71 km
6
OH (1/cm3)
N2 + p (E)
N+
2 + O2
O+
2 + O2 + M
O+
4 + H2 O
...
+
O2 (H2O)2 + H2O
+
H3O (OH)H2O + H2O
H+(H2O)3 + H2O + M
H+(H2O)4 + e−
−−−
Net : H2O
−
+
N+
+
e
+
p
(E
2
O+
2 + N2
O+
4 +M
O+
2 (H2O) + O2
06
07
08
09
10
11
12
13
14
H3O (OH)H2O + O2
+
H (H2O)3 + OH
H+(H2O)4 + M
H + 4H2O
−−−
→ OH + H
6
17
18
19
Night
Daytime
4
2
0
−2
−4
05
06
07
08
09
10
11
12
13
Day in 2006/12
14
15
16
17
18
90
90
80
80
70
70
60
50
50
40
30
30
SIC
MLS
0
2
4
6
OH (1/cm3)
8
Below: A diagram of hydrogen and nitrogen conversions due to
ionic reactions. The species in the gray boxes are affected by positive ion chemistry, while NOy redistribution by negative ion chemistry
affects the species inside the blue box. NO, HNO3, and H2O are directly affected by both positive and negative ion chemistry. Note
that all-neutral reactions, e.g. production of NO from N(2D), are not
included in the diagram.
60
40
20
19
08−Dec−2006 12:00:00
Altitude (km)
Altitude (km)
−
+
N+
+
e
+
p
(E − ∆E)
2
O−
2 + O2
O−
3 + O2
CO−
3 + O2
NO−
3 + CO2
NO−
3 (H2O) + M
NO−
3 (HNO3) + H2O
HNO3 + HNO3 + 4H2O
−−−
→ OH + HNO3 + O2
→
→
→
→
→
→
→
→
16
Difference: SIC − MLS
6
x 10
08−Dec−2006 03:35:00
N2 + p+(E)
O2 + O2 + e−
O−
2 + O3
O−
3 + CO2
CO−
3 + NO2
NO−
3 + H2 O + M
NO−
3 (H2O) + HNO3
+
NO−
(HNO
)
+
H
(H2O)4
3
3
−−−
Net : H2O + O3 + NO2
15
+
OH (1/cm3)
+
Below: Example of P/Q tables, numbers given with respect to altitude, ionization rate, solar zenith angle, and season of year.
SIC
MLS
10
6
x 10
20
0
2
4
6
OH (1/cm3)
8
10
6
x 10
References
• P.T. Verronen et al., Nitric Acid Enhancements in the Mesosphere During the January 2005 and December 2006 Solar Proton Events, J. Geophys. Res., 116, D17301, doi:10.1029/2011JD016075, 2011.
• P.T Verronen et al., About the increase of HNO3 in the stratopause region during the Halloween 2003 solar proton event, Geophys. Res. Lett., 35, L20809, doi:10.1029/2008GL035312, 2008.
• P.T. Verronen et al., Production of Odd Hydrogen in the Mesosphere During the January 2005 Solar Proton Event, Geophys. Res. Lett., 33, L24811, doi:10.1029/2006GL028115, 2006.