Stratospheric warmings & Ionospheric F2- region Variability: O(1S)dayglow
a proxy to thermospheric dynamics

2014 AOSWA (Asia-Oceania Space Weather Alliance) Workshopon“Space Environment Impacts and Space Weather Forecast Models”
2-5, March 2015, Fukuoka, Japan.

A.K Upadhayaya
CSIR-National PhysicalLaboratory, New Delhi,India

SSW & Ionospheric F2- region Variability: O(1S) dayglow
a proxy to thermospheric dynamics contd……..

Outline of talk : Meteorological Influence on Ionosphere : SSW
 Observations and Results
 F2 region response to geomagnetic disturbances across Indian latitudes:
O(1S) dayglow as a proxy to thermospheric dynamics
 Observations and Results
 Summary & Conclusions

Ionospheric F2- region: Variability and Sudden
Stratospheric Warmings

Objective:
To examine Ionospheric F2- region, variability and sudden
stratospheric warmings

Upadhayaya, A. K., and K. K. Mahajan (2014), Ionospheric F2 region: Variabilityand sudden stratospheric warmings, J. Geophys. Res. Space Physics, 118,
doi:10.1002/jgra.50570.

Introduction
The possibility of links between the meteorological phenomena and the upper
atmosphere have been discussed very profoundly during the last decade (e.g. Hagan etal.,2001; Abdu et al., 2006; Lastovicka ,2006 ; Fuller-Rowell et al.,2008) .
 One of the well known meteorological phenomenon which could be an important agent
in this link is the large meterological variation in the winter time polar stratosphere, called
the sudden stratospheric warming (SSW). During a SSW there is a sudden increase instratospheric temperature, (which could be as large as 70 K), the polar vortex shifts off thepole and the zonal wind (U) become weak. This type of warming is designated as minor.
However, if the vortex breaks up, and the zonal wind (U) changes direction then the event
is designated as a major SSW.
Although there have been some early attempts for identifying any ionospheric response
to meteorological events like the sudden stratospheric warmings from theory, as well asfrom measurements (e.g. Liu and Roble 2002, Kazimirovsky et al., 1971 , Danilov andVanina 2003), the field has seen relatively a vigorous activity only recently.

Continue….
Most of these studies have been confined to the western hemisphere, particularly the 75ºW
meridian. In view of the large longitudinal dependence of the equatorial electrodynamic
perturbations during SSWs, we have attempted to examine ionospheric effects following SSW
events of 2007, 2008 and 2009 in the Asian zone by using ionosonde data from six differentstations. These stations cover a broad latitude range from 23º N to 45º N.
We find there are some perceptible changes in the ionosphere following these warmings atthese stations.
We then compare the magnitude of these changes with the normal day-to-day and hour-tohour variability which exists in the ionospheric F2 region even at times when there are no SSWs
and solar and magnetic indices are quite stable and close to their lowest values.

Observations and Analysis:

In our study for examining the ionospheric response to SSWs, we have used the hourly data of F layer
critical frequency (foF2) from four Japanese stations namely Kokubunji, Okinawa, Yamagawa, Wakkanai
and three Indian stations. Geographic and geomagnetic co-ordinates of these stations along with otherrelevant parameters are given in Table1. The foF2 data are based upon vertical sounding with ionosondes
and have been downloaded from SPIDR web, managed by National Geophysical Data center, Boulder andfrom NICT Japan world data center. The ionosondes at these stations produce ionograms, which arerecorded digitally on a computer storage medium. The digitally-recorded ionograms are collected from eachstation by a central computer and these are reduced to numerical values and to summary plots by anautomatic processing system. In addition to Japanese stations, we have also used the ionospheric datafrom the low-mid latitude station Delhi and the equatorial crest anomaly station Bhopal. These data are
obtained by using digital ionosonde system IPS-71 of Kel Aerospace Ltd.

Table 1. Locations of Ionosonde Stations
StationGeographic
Latitude.

Geographic
Longitude.

Geomagnetic
Latitude

Dip

Trivandrum

8.36ºN

76.6ºE

0.630S

0.50

Bhopal23.29ºN

77.46ºE

14.2°N

33.20

Okinawa

26.60N121.80E

17.00N

36.80

Delhi

28.20N

77.60 E

19.20N

42.4°

Yamagawa

31.2°N

130.6°E

21.7°N

43.8°

Kokubunji

35.71°N

139.49°E

26.8°N

49º

Wakkanai

45.1°N141.7°E

36.4°N

59.3°

We have examined ionospheric response to thefollowing SSW events.
• Winter of 2008-2009• Winter of 2007-2008• Winter of 2006-2007

Summary of stratospheric andgeomagnetic conditions for thewinter of 2008–2009.

Peak of warming: 23-24 Jan 2009

Fig 1. (Top to bottom): Stratospheric temperature at 90°N and 10 hPa (~32 km), zonal mean stratospherictemperature at 60°N–90°N, zonal mean zonal wind at 60°N, planetary wave 1 activity at 60°N
and10 hPa, planetary wave 2 activity at 60°N and 10 hPa, F10.7 index, and Kp index. Lines indicate 30year means of stratospheric parameters, and solid circles indicate data for the winter of 2008–2009.( FromGoncharenko 2010 )Winter of 2008-2009

Quiet period 3-12 Jan 2009 was used to characterize the normal
behavior of quiet-time ionosphere.

Plots of F2 layer critical frequency (foF2) and (ΔfoF2) with days of the year 2009 at (a) Okinawa, (b)Yamagawa and at (c) Kokubunji. Plots of F10.7 (d) and Kp indices (e) with days of the year 2009

Fig 4. Plot of average F2 layer critical frequency (foF2) with days of the year 2009 for forenoon andafternoon. Forenoon foF2 values remain higher than the afternoon for several days after the warming. On
other days forenoon values are lower than the afternoon foF2 values.

Summary of stratospheric andgeomagnetic conditions for the winterof 2007-2008

Quiet period 2-11 Jan 2008 was used tocharacterize the normal behavior ofquiet-time ionosphere.

Same as Figure 1, but for the winter of 2007–2008. Four stratospheric warmings occurred, with peaks on 24January, 6 February, 16 February, and 23 February, 2008.
(From Goncharenko 2010 )Winter of 2007-2008

Plots of F2 layer critical frequency (foF2) and (ΔfoF2) with days of the year 2008 at (a) Okinawa, (b)Yamagawa and at (c) Kokubunji ,(d) Wakkanai (e) Bhopal, and (f) Delhi. Plots of F10.7 (g) and Kp indices(h) with days of the year 2008.

Summary of stratospheric andgeomagnetic conditions forthe winter of 2007–2008.
Peak of warming: 24-27 Feb 2007
2-4 March 2007.

Fig 1. (Top to bottom): Stratospheric temperature at 90°N and 10 hPa (~32 km), zonal mean stratospherictemperature at 60°N–90°N, zonal mean zonal wind at 60°N, planetary wave 1 activity at 60°N
and10 hPa, planetary wave 2 activity at 60°N and 10 hPa, F10.7 index, and Kp index. Lines indicate 30year means of stratospheric parameters, and solid circles indicate data for the winter of 2007–2008).

Winter of 2007-2008

Plots of F2 layer critical frequency (foF2) and (ΔfoF2) with days of the year 2008 at (a) Okinawa, (b)Yamagawa , (c) Kokubunji ,(d) Wakkanai and (e) Bhopal. Plots of F10.7(g) and Kp indices(h) with days ofthe year 2007.

Plots of variation of foF2 (ΔfoF2) fromPlot of 5- point running average of foF2 atnormal quiet period at (a) Bhopal and at Bhopal and Trivandrum along with EEJ(b) Trivandrum along with the EEJ
strength at 14:00 and 16:00 hrs Indian
strength (c) for the first six months ofStandard Time (IST) for first three months of2007
the year 2007

Plot of 5- point running average of foF2 at
Bhopal and Trivandrum along with EEJ
strength at 14:00 and 16:00 hrs IndianStandard Time (IST) for first three months ofthe year 2008(a) EEJ and (b) foF2 over Bhopal duringJanuary to March 2007 and (c, d) theirLomb-Scargle spectral analysis.

Plot of foF2 for all local times for the first six months of the year 2008

Results:
Based on our investigation on the extent of ionospheric changes observed following the three SSW
events of 2007, 2008 and 2009 using ionosonde data from six different stations in the Asian zone,
the following conclusion are drawn from the analysis.
There are perceptible ionospheric perturbations which can be linked to these warmings.
These perturbations are in the form of enhancements and depressions in foF2 resulting in peakelectron density variations which could be larger than 200% when compared with the normal
magnetically quiet time ionosphere.
The low latitude station Okinawa (26.60N ,121.80E ) showed semidiurnal ionospheric perturbations
during the SSW event of 2009, a feature previously reported from the total electron content
measurements (e.g. Goncharenko et al., 2010b, Liu et al., 2011a, Anderson and Araujo-Pradere,2010, Yue et al., 2010 , Sripathi and Bhattacharyya, 2012). This feature was not found during theSSW event of 2008. On the other hand the “EIA Crest” station Bhopal (23.29ºN, 77.46ºE), showedsome evidence of 6-hour periodicity in ionospheric changes during the SSW event of 2007.
During the SSW event of 2008, ΔfoF2 was predominantly depressed soon after the first warming. In
the other two cases ΔfoF2 was enhanced.
A 13-14 day periodicity in ionospheric perturbations was seen for the SSW event of 2007. Similar
periodicity in ionospheric perturbations has earlier been reported by Fejer et al., 2010, 2011 andSripathi and Bhattacharyya, 2012 during such SSW events. However we found some evidence of 3-4
and 4-5 day periodicities in ionospheric perturbation following the SSW events of 2009 and 2008
respectively.
The highest and lowest values of foF2 during the six month period, January to June for the years
2007, 2008 and 2009 generally occurred during the SSW events at almost all the stations.
In view of the large variability within the ionosphere, it is difficult to quantify the changes as well as
the response times in the ionosphere to these stratospheric warmings.

Acknowledgments.
The authors are thankful to NICT Japan World Data Center for making the ionospheric data available onits web site

F2 region response to geomagnetic disturbances acrossIndian latitudes: O(1S) dayglow as a proxy to thermosphericdynamics

Objective:
F2 region response to geomagnetic disturbances acrossIndian latitudes: O(1S) dayglow as a proxy tothermospheric dynamics

Upadhayaya, A. K JASTP ( 2015)

Introduction

The responses of the upper atmosphere to geomagnetic activity have beenstudied for a long period of time to the present, using experimental techniques aswell as theoretical models. Many reviews on this topic cover the subject in details(e.g., Abdu, 1997; Fuller-Rowell et al., 1997; Rees, 1996; Schunk and Sojka, 1996;
Buonsanto, 1999, Danilov and Lastoviˇcka 2001; Kelley et al., 2011, Balan et al.,2011).
 It is quite often seen that the normal ionospheric variability (which cannot beassociated with an event) is at times even larger than the variability due to atransient (solar storm) or meteorological event. A good part of this unansweredreason for the variability could perhaps be related to possible changes in theneutral composition in thermosphere. While there are daily indices like F10.7 andAp or Kp for solar ionizing radiation and magnetic activity respectively, there arenone to represent daily changes in neutral atmosphere and electrodynamics. Briefly,
this seems to be a major reason for the inability to explain the day-to-day and hourto- hour variability seen in ionospheric F2- layer.
In the present study an attempt is made to examine the response of equatorial
and low latitudes F-region ionospheric parameters (foF2 and h’F) during thedisturbed periods of geomagnetic storms and to investigate the response of green
line dayglow emission under quiet and strong geomagnetic conditions.

Observations and Analysis:
The variation in F2 layer parameters over equatorial stations Thiruvananthapuram (8.5°N, 76.8°E), and low
latitude station, Delhi (28.6°N, 77.2° E) are examined during five geomagnetic storms occurred at different
local times of varying strength. The change in the orientation of Z component of Interplanetary Magnetic
Field (IMF), Bz and variation in Dst index intensity are taken as the indicator of magnetic conditions. Thegeomagnetic storm events occurred during April, October and November - 2001, November-2003 and April2006 having minimum Dst excursion of –271, -148, -221, –422 and -98 nT respectively are considered forthe present study. The NRLMSISE-00 [Picone et al., 2002] and IRI-2007 [Blitza and Reinisch, 2008 ]empirical models which is incorporated in the GLOW model is used to specify the neutral atmosphere andinitial electron density profile with HEUVAC solar flux model (Richard et al., 2006) . The 3- hour indices Ap
are used in NRL MSIS00E for considering the magnetic activity dependence of the neutral constituents andtemperature. The Glow model run is carried out under quiet (Ap=20) and strong (Ap=200) geomagneticconditions in a common medium solar EUV ionizing radiation condition (F10.7=130)

Summary of the Magnetic storm events.
SSC*Minimum Dst(EMT(EMT=UT+5)

Year

MonthBegin Day

2001

04

112100-271

2001

1124

1000-221

2001

1010025-148

2003

1120

1700-422(nT)The variations under strong geomagnetic conditions causes
a decrease in production processes for the reaction
N2(A3Σu+) to atomic oxygen, which lead to a decrease inemission rates of greenline dayglow emission

In the thermosphericemission peak region(150–175km) there arethree important
reactions which
contribute to theproduction of O(1S).
These sources are
dissociative
recombination (O2+ +e), energy transferfrom N2(A3Σu+) toatomic oxygen(N2(A3Σu +) +O) andthe photoelectron
excitation of atomic
oxygen (e + O).

Summary and Conclusions:
•••

•

•

The responses of F-region ionospheric parameters (foF2 and h’F) to geomagnetic storm at equatorial
and low latitude stations are anti-correlated. A correlation coefficient varying from 0.44 to 0.62 wasobserved in ΔfoF2 between equatorial and low latitude station Thiruvananthapuram and Delhi for thefive storm event considered. The reaction as seen at different ionospheric stations may be quite
different during the same storm depending on both the geographic and geomagnetic coordinates of thestation, storm intensity and the storm onset time.
It is observed that the maximum deviation in F2 layer characteristic parameters (foF2 and h’F) isobserved during the recovery phase of the storm. This indicates that ionospheric response is seen afterfew hours from the SSC of the storm and this time will in- turn depend on thermospheric dynamics.
The variation in modeled greenline dayglow intensity at thermospheric peak height at equatorial andlow latitude stations during these five storm events by in large showed a decrease coinciding with theonset of the storm. Variations of about 23 to 40 % in modeled greenline dayglow intensities wereobserved for the five storm events considered. Largest variation in the O(1S ) intensity was seen for theseverest of the storm considered.
The variations under different geomagnetic conditions causes a decrease in production processes forthe reaction N2(A3Σu+) to atomic oxygen, which lead to decrease in emission rates of greenline dayglowemission.
The updated GLOW model results shows that thermospheric peak of greenline dayglow emission showsa response to changing geomagnetic conditions, therefore greenline dayglow emission can be apotential candidate to be considered as a proxy to the thermospheric dynamics. However, the validationof above results is constrained due to lack of observations which will be taken up in future.Thanks for you kind attention
Looking forward to collaborations…

The three main contributing reactions responsible for production of redline dayglow
emission are :1. The dissociative recombination (shown in green)
O2+ + eth  O( 1D) + O(3P)
2. The photoelectron impact on atomic oxygen (shown in blue)
O(3P) + eph O(1D) + eph
3. Photo dissociation of molecular oxygen (shown in yellow)
O2 + hυO(1D) + O(3P)It can be seen from Fig. 3 that when the activity changes from low to high the ratio of concentration ofatomic oxygen increases by a factor of 1.5, molecular oxygen by a factor 2.1 and molecular nitrogen by afactor of 4.3. As seen, the large increase in photo dissociation reaction under strong geomagnetic
activity is primarily because of increase in O2 concentration (which roughly increases by a factor of 4.3).
The decrease in contribution from dissociative reaction is attributed to a decrease in electron
concentration during high geomagnetic activity this result was reported by Culot et al., 2005. It has beenfound that the quenching of O(1D) excited state with molecular Nitrogen is the main dominating
deactivation process leading to loss under strong geomagnetic conditions. So loss due to this reaction
balances the increase in production due to other sources and thus results in a constant emission rate ofO(1D) under varying geomagnetic conditions. Similar results with small variations in magnitudes ascompared to our model study were also reported by Culot et al. 2005. In their report they have used
one-dimensional fluid/kinetic model code (TRANSAR) to simulate the effects of varying geomagnetic
activity on green and redline emissions. They have shown that the variation of green line intensity
follows well the variation of the magnetic activity, but that the intensity of redline does not vary in anextent that could be measured or modelled. These observed results are also in accordance to the WINDII
observations (Shepherd et al. 993).