1. Mid-latitude Electron Density Variations Under Magnetospheric Substorm Conditions As Determined From Istanbul Dynasonde Observations
Aysegul Ceren MORAL, Zerefsan KAYMAZ, Emine Ceren KALAFATOGLU
Istanbul Technical University, Turkey
Corresponding author:

2. Summary and Conclusions
OUTLINE
Purpose
Data
Summary and Conclusions
General trends
Daily variations
Monthly variations
Seasonal variations
Substorm effects
Literature work
Case studies
Electron density height profiles
Model comparison
Moral, Kaymaz, Kalafatoglu AOGS 2014 Sapporo Japan July-1 Aug 2014

3. INTRODUCTION
Magnetospheric substorms are the means to transfer energy from the magnetosphere into the ionosphere. 
The energetic particles and auroral electrons from the magnetosphere precipitate along the field lines and deposit their energy as heat at around E-region heights, 120 kms. 
This increases the ionization in the E layer and above, and the temperature as a consequence of Joule heating.
In this project, we study the variations in the F2 layer under the substorm conditions, using Istanbul Dynasonde electron density observations.
Moral, Kaymaz, Kalafatoglu AOGS 2014 Sapporo Japan July-1 Aug 2014

4. Ionosonde System at ITU
The Dynasonde
operating since October 2012
located within the ITU campus in Istanbul (41N, 29E)
Run by Space Weather Lab at ITU
ionograms at every 4 min resolution. 
NeXtYZ software (Nikolay Zabotin, University of Colorado)
79 ionospheric parameters for E and F2 layers including
critical frequency (foF2, foE)
Critical height (hmFo, hmE)
total electron content (TEC),
electron density profile
Moral, Kaymaz, Kalafatoglu AOGS 2014 Sapporo Japan July-1 Aug 2014

5. DATA Use foF2, hmF2 and electron density (ne)
Determine the storm/substorm conditions
Mid-latitudes, İstanbul:
Geographic Latitude: 42o,
Geomagnetic Latitude: 35o
The effects of substorms
positive and a negative deviation from a quiet day variation.
Dst < -40 nT disturbed i.e. Storm conditions
AE > 100 nT disturbed, Auroral substorn conditions
Studied two cases where we have seen the positive and negative phases
Preliminary results are presented
Moral, Kaymaz, Kalafatoglu AOGS 2014 Sapporo Japan July-1 Aug 2014

6. Examples from Literature
TEC contours
Latitudes from
Narssarssuaq (63o)
Goose Bay (60o)
Sagamore Hill (54o)
KSFC (42o)
4 days interval
Subtract: Storm day-Quiet day
Positive phase
(Red contours)
Higher density than that in quiet day
1 day
Negative phase
(Blue contours):
Lower density than that in quiet day
3 day
Mendillo, 2006, Reviews of Geophysics, 44, RG4001
Positive phase
Negative phase
İstanbul Geomagnetic Latitude (35o)
Moral, Kaymaz, Kalafatoglu AOGS 2014 Sapporo Japan July-1 Aug 2014

7. Substorm Signatures
Classified the signatures observed during substorms
5 types were recognized
Prölls, G.W., (1995), In Handbook of Electrodynamics, vol.2, ed. H.Holland
Moral, Kaymaz, Kalafatoglu AOGS 2014 Sapporo Japan July-1 Aug 2014

8. General trends Daily Monthly Seasonal
Moral, Kaymaz, Kalafatoglu AOGS 2014 Sapporo Japan July-1 Aug 2014

9. AN EXAMPLE IONOGRAM: 21 April 2013
09 UT
12 LT
21 UT
00 LT
Moral, Kaymaz, Kalafatoglu AOGS 2014 Sapporo Japan July-1 Aug 2014

10. MONTHLY VARIATION: f0F2 2012 foF2 Sep Nov Oct May Apr Mar Jun Jul Aug
Feb
Jan
Dec
Moral, Kaymaz, Kalafatoglu AOGS 2014 Sapporo Japan July-1 Aug 2014

11. SEASONAL VARIATION 2012 f0F2 foF2 hmF2 foF2
High daytime electron density at spring noon
Lowest night time electron density during winter nights
Lowest daytime electron density in summer
High fluctuations in summer
hmF2
Lowest hegihts during summer daytime
Fall
Spring
Winter
Summer
Fall
Spring
Winter
Summer
Moral, Kaymaz, Kalafatoglu AOGS 2014 Sapporo Japan July-1 Aug 2014

12. Storm/Substorm Relation
Using Dst and AE magnetic indices, we have determined two strong magnetospheric substorm
Then we selected a very quiet day
We investigated the variations in foF2 and TEC for these two days by subtracting the quiet day variation from disturbed day variation
Dif=Disturbed – Quiet
Positive differences mean foF2 is higher during disturbed days
Negative differences mean foF2 during disturbed days is lower than foF2 observed during quiet day.
Case selection is based on
Dst < -40 nT  Storm
AE > 100 nT  Auroral Substorm
Dif > 0  Positive Phase
Dif < 0  Negative Phase
Moral, Kaymaz, Kalafatoglu AOGS 2014 Sapporo Japan July-1 Aug 2014

13. CASE 1: 17 MARCH 2013 Positive phase
Moral, Kaymaz, Kalafatoglu AOGS 2014 Sapporo Japan July-1 Aug 2014

14. CASE 1: 17 MARCH 2013 Difference 12 UT
Moral, Kaymaz, Kalafatoglu AOGS 2014 Sapporo Japan July-1 Aug 2014

15. CASE 2: 14 NOVEMBER 2012 Positive phase Negative phase
Moral, Kaymaz, Kalafatoglu AOGS 2014 Sapporo Japan July-1 Aug 2014

16. CASE 2: 14 NOVEMBER 2012 Difference
Moral, Kaymaz, Kalafatoglu AOGS 2014 Sapporo Japan July-1 Aug 2014

17. Differences Positive Phase Negative Phase Time UT Dst AE Dif. foF2 4
-10 42
-0.07 6 -7
111
-0.08 13
-88
986
2.29 18
-99
1452
0.56 21
-132
836
1.11
Positive Phase
Time UT
Dst AE
Dif.
foF2 3
-77
936
0.17 4
-92
1009
0.65 9
-100
627
-2.18 12
-73
152
-0.87 18
-50 63
0.96
Negative Phase
Moral, Kaymaz, Kalafatoglu AOGS 2014 Sapporo Japan July-1 Aug 2014

18. Electron density Height Profiles: Comparisons with models Case-1: March 17, 2012
Positive phase
IRI: International Reference Ionosphere
TIEGCM: Thermosphere Ionosphere Electrodynamics General Circulation Model

19. Electron Density Height Profiles: Comparisons with models Case-2: Nov 13-14 2012
Negative phase
Moral, Kaymaz, Kalafatoglu AOGS 2014 Sapporo Japan July-1 Aug 2014

20. SUMMARY & CONCLUSIONS
Preliminary results from Istanbul, Turkey, Dynasonde
foF2 variations: daily, monthly, seasonal
High fluctuations both in foF2 and hmF2 are seen during the summer months with less electron density compared to those of winter time.
Indicating the role of the atmospheric dynamics during the summer months
Storm/substorm effects on ionospheric density over Istanbul, a midlatitude station
Presented 2 Case study
(Disturbed – Quiet) day differences
Positive/negative differences corresponding to changes in Dst and AE
Positive phase  1 day or a little over 1 day (extending to the next day)
Electron densities are higher by about %17 during positive phase at 12:00 UT noon
Largest differences were found during the mid-day (12 noon) and afternoon times extending toward dusk (06 UT)
Negative phase  1 day
Electron densities are lower by about %17 during negative phase at 09:00 UT
Moral, Kaymaz, Kalafatoglu AOGS 2014 Sapporo Japan July-1 Aug 2014

21. SUMMARY & CONCLUSIONS Future Work;
Height profiles were compared with model results.
IRI underestimates height of the peak electron density closer to the observations
These are expected as the model does not include magnetosphere-ionosphere coupling
TIEGCM model gives closer agreement with observations during the positive phase of the storms
It overestimates the height of the electron density peak during the positive phase
TIEGCM overestimates both the peak electron density and the height during the negative phase of the substorms
Future Work;
Statistical studies on the response of the ionosphere to substorms still continue
2012 and 2013 complete statistics
Moral, Kaymaz, Kalafatoglu AOGS 2014 Sapporo Japan July-1 Aug 2014

22. ACKNOWLEGDEMENTS
This study has been supported by Turkish Scientific and technological Council (TUBITAK), project No= 113Y213
Moral, Kaymaz, Kalafatoglu AOGS 2014 Sapporo Japan July-1 Aug 2014

23. Thank you for your attention !...
Moral, Kaymaz, Kalafatoglu AOGS 2014 Sapporo Japan July-1 Aug 2014