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Effect of solar proton events and medium energy electrons on the middle atmosphere
using a 3D Whole Atmosphere Community Climate Model with D region ion-neutral chemistry
Wuhu Feng1,2, Tamás Kovács1, John M.C. Plane1, Martyn P. Chipperfield2,
Pekka T. Verronen3, Monika Andersson3, David A. Newnham4, Mark Clilverd4, Daniel R. Marsh5
1 School of Chemistry, University of Leeds, UK
3 Finnish Meteorological Institute, Helsinki, Finland
5 National Center for Atmospheric Research, Boulder, USA
1. Introduction
2 NCAS, School of Earth and Environment, University of Leeds, UK
4 British Antarctic Survey, Cambridge, UK
[email protected], [email protected], [email protected]
2. 3-D Atmospheric Models
It is crucial to understand the sources of odd nitrogen
NOx (NO, NO2) and odd hydrogen HOx (OH, HO2)
since they play important roles in the chemistry of
stratospheric and mesospheric O3. In the middle and
upper atmosphere, NOx and HOx are produced
directly through the interactions of ionizing particles
with atmospheric gases. During solar proton events
and geomagnetic activities, the enhanced ionizations
produce a large amount of NO in the middle
atmosphere by complex ion chemistry. Recently we
have developed a new coupled ion-neutral chemical
model for the ionospheric D region (altitudes ~50 - 90
km) based on the Sodankylä Ion and neutral
Chemistry (SIC) model and 3D Whole Atmosphere
Community Climate Model (WACCM), termed as
WACCM-SIC. Here we describe the three different
WACCM model developement with detailed D
chemistry (WACCM-SIC now includes an extra 306
ion-neutral and ion-recombination reactions of neutral
species, positive/negative ions and electrons).
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Whole Atmospheric Commnity Climate Model uses NCAS CESM framework.
Option of data assimilation from available meteorological analyses.
Detailed dynamics/physics/chemistry from surface up to 140 km.
1.9ox2o horizontal resolution and 88 vertical levels.
Ion chemitry and other key parameters (Solar cycle, Solar Proton Events etc.).
Three additonal developmented versions including D region chemistry:
a) WACCM-D: 307 reactions of postive/negative ions (Verronen et al., 2016);
b) WACCM-SIC: Full SIC chemistry (Kovacs et al., 2016);
c) WACCM-rSIC: a reduction of SIC chemistry using Simulation Error
Minimization Connectivity Method (Kovacs et al., 2016) .
For the WACCM-D, WACCM-SIC and WACCM-rSIC, the productions of NOx
and HOx due to MEE are now included.
Ionosation rates for electron engery range (30-1000 keV) are now also
considered for WACCM-SIC and WACCM-rSIC.
WACCM, WACCM-D, WACCM-rSIC, WACCM-rSIC have done to investigate
the impact of a medium SPE of 15-17 January 2005.
WACCM-SIC and WACCM-rSIC model simulations with or without MEE have
been performed to investigate the effect of MEE of 2013-2015 on the middle
atmospheric species (NOx, HOx, HNO3 and ozone).
3. SIC, rSIC for SPE condition
Fig1. Major neutral/ion profiles from SIC and rSIC.
181 reactions are identified for rSIC to simulate
well compared with full SIC mechanism with 5%
tolerance for important species in the D-region.
SIC chemical reactions, mechanism reduction and simulation conditions
Method: Determination of the summed square of the normalized Jacobian
elements of the concentrations
An element of the Jacobian ci f j f j ci 
shows how much the rate of formation of the species j will change on the
2
N 

concentrations of species i.
f
 ci j 
Bi  
j 1
Verronen et al.,
JAMES, 2016.
 f c 
 j i
The summed square of changes (Bi) represents the direct relationship
between the rate of concentration change of species i and the rate of
concentration change of the (j=1,…,N) important species. Species with
large Bi values are closely linked to the important species therefore their
presence is necessary in the model. Then iteration is done as follows: in
each step the actual highest Bi is added into the summation and new B is
calculated. Iteration is repeated until a gap appears in the Bi values.
Species having Bi values above the gap are closely linked to the important
species: these are the necessary species.
4. Rapid NO increase after SPE event
5. Rapid NO2 increase after SPE event
8. Solar cycle impact
Fig.2. Polar region NO (60-90o N) profile during January 2005. NO
production (loss) is mainly due to positive (negative). NO reacts
with major negative ions (O-, CO3-, ClO-) in D region.
7. Rapid OH increase after SPE event
Fig.5 Similar as Fig. 2, but for OH. OH is also influenced by
negative ion reactions of O-, OH- and CO3-.
Fig.3 Similar as Fig. 2, but for NO2. Larger NO2 increase in WACCM
can be explained by the missing of anion chemistry. WACCM-D
has not included O2+ and N2 clusters of proton hydrates.
8. Rapid O3 decrease after SPE event
Fig.6 Similar as Fig. 2, but for O3. Importance to include the
important reactions for positive cluster ions and negative ions in
the model to better simulate the mesospheric ozone.
Selected date for reduction:
29.10.2003. Maximum of large SPE (Oct/Nov 2003)
Selected date for model simulation:
January 2005. Medium SPE
Selected initial important species:
Neutrals: HNO3, O3, H2O2, NO, NO2, HO2, OH, N2O5
Ions: O2+, O4+, NO+, NO+(H2O), O2+(H2O), H+(H2O),
H+(H2O)2, H+(H2O)3, H+(H2O)4, O3-, NO2-, O-, O2-, OH-, O2(H2O), O2-(H2O)2, O4-, CO3-, CO3-(H2O), CO4-, HCO3-,
NO2-, NO3-, NO3-(H2O), NO3-(H2O)2, NO3-(HNO3), NO3(HNO3)2, Cl-, ClOSelected D-region altitudes for the reduction:
60km, 70km, 80km, 90km
WACCM-SIC and WACCM-rSIC are described in details
in Kovacs (GMDD, 2016).
6. HNO3 increase due to D chemistry
9. Summary and conclusion
Fig.4 Similar as Fig. 2, but for HNO3. Negative ion
chemistry causes significant HNO3 enhancement.
Most formation is from H+(H2O)m+NO3-(HNO3)m.
Reduction of HNO3 is mainly due to reactions with
NO3-(H2O), NO3-(HCl), CO3-, O-, O2- and Cl-.
9. Impacts of MEE on NO
Fig.7 Time series of partial column abundance of NO
measured by Halley microwave radiometer and
simulated by WACCM with/without MEE. Model
gives a reasonable NO simulation during a quite
geomagnetic activity condition in 2014 but largely
underestimates the enhancement of NO for the
moderate and strong geomagnetic conditions.