Storm-time total electron content and its response to penetration electric fields over South America

1

• Storm-time total electron content and its
  response to penetration electric fields over
  South America
• P. M. de Siqueira, E. R. de Paula, M. T. A. H.
  Muella,
• C. M. Paulo, L. C. Viera
• 09/11/2011

2
Introduction

• We present the response of the ionosphere due to
  the severe magnetic storm of 710 November 2004.
• GPS Total Electron Content (TEC) maps of South
  America region were analyzed.
• Ionospheric vertical drift data obtained from
  Jicamarca ISR are used in the analysis in order
  to verify the disturbed zonal electric fields
  during the superstorm.
• The vertical drifts were also inferred from ?H
  magnetometer data (Jicamarca-Piura) following the
  methodology presented by Anderson et al. (2004).

3
Introduction

• Penetration electric fields were observed by
  comparing the equatorial vertical drifts and the
  Interplanetary Electric Field (IEF).
• TEC maps reveal unexpected plasma distributions
  and TEC levels during the main phase of the
  superstorm on 7 November.
• The results also reveal well known
  characteristics of the plasma distributions on 8,
  9, and 10 November.
• The emphasized features are the expansion and
  intensification of EIA due to prompt penetration
  electric fields on November 9 and the inhibition
  of EIA during post-sunset hours on November 7, 8,
  and 10.

4
General Scenario of the Superstorm First
increase in Sym-H around 12 UT on Nov.
07. Minimum Sym-H -394 nT on Nov. 08, 0555UT.
5

• TEC responses on November 07, 2004.

6
Jicamarca LT UT 5 hours

• Black line (third panel) is referred to modeled
  vertical drifts (using ?H Jicamarca-Piura data in
  a neural network).
• Vertical drifts are smaller compared to quiet
  time before 15 UT and before the SSC.

7
Jicamarca LT UT 5 hours
Daytime negative vertical drifts (DD)

• Prompt Penetration Electric Field (PPEF) event
  occurs from 15 to 17 UT.
• Vertical drifts are negative from 17 to 18 UT.
• SSC occurs around 1830 UT.
• Pre-reversal enhancement (PRE) is present
  (dhF/dt from Jicamarca digisonde).

8
Nov. 06 Nov. 07

• TEC maps
• ? denotes the geographic positions of GPS
  receptors.
• Nov. 06 is the quiet time reference.
• Top 1600 UT (13 LT at Brazil)
• Bottom 1630 UT (1330 LT).
• Higher TEC absolute values on Nov. 07 after the
  PPEF event.
• No significant differences.

9
Nov. 06 (19 LT Brazil) Nov. 07
(19 LT Brazil)

• During PRE hours (after sunset).
• Smaller TEC on Nov. 07 at 19 LT (Brazil)
• EIA crests are diminished.

10
Nov. 06 (20 LT Brazil) Nov. 07
(20 LT Brazil)

• EIA is developed on Nov. 06 at 20 LT (quiet time
  reference).
• EIA disappears on Nov. 07 from 20 LT on (even
  though the occurrence of PRE).
• This is probably due to the smaller vertical
  drifts on Nov. 07 during daytime (being negative
  in some hours).

11

• TEC responses on November 08, 2004.

12
Jicamarca LT UT 5 hours
Daytime drifts

• Flat IEF Ey (IMF Bz near zero during this
  period).
• Daytime vertical drifts near zero during daytime
  (sometimes negative).
• Second panel green line is referred to sunset
  hours denoting a weak PRE (20m/s).
• These vertical drifts reflect the action of
  disturbance dynamo fields.

13
Nov. 06 (12 LT Brazil) Nov. 08
(12 LT Brazil)

• Nov. 06 quiet time reference.
• TEC enhancement confined to the geomagnetic
  equator and magnetic low-latitude.
• Typical effect of disturbance dynamo electric
  fields.

14
Nov. 06 (1830 LT Brazil) Nov.
08 (1830 LT Brazil)

• EIA starting to develop at 1830 LT (Brazil) on
  Nov. 06.
• EIA absent on Nov. 08 and TEC enhancement
  prevails over the geomagnetic equator.

15
Nov. 06 (1930 LT Brazil) Nov.
08 (1930 LT Brazil)

• EIA developed at 1930 LT (Brazil) on Nov. 06.
• EIA also developed on Nov. 08 (1930 LT Brazil).
• The weak PRE occurred on Nov. 08 was efficient to
  develop EIA after 1930 LT.

16

• TEC responses on November 09-10, 2004.

17
Jicamarca LT UT 5 hours

• Second Panel green line is referred to vertical
  drifts measured at Jicamarca ISR.
• Great PPEF event occurs on Nov. 09, from 1930
  UT to 21 UT (vertical drifts reach 120m/s)
  during a recurrent and very intense magnetic
  storm.

18
Nov. 09
Nov. 10
Jicamarca LT UT 5 hours
nighttime

• Vertical drifts quite disturbed on Nov. 10
  (nighttime).
• Daytime vertical drifts (after 12 UT on Nov. 10)
  present a partial recovery to quiet time
  patterns.
• Absence of PRE on Nov. 10.

19
Nov. 06 (12 LT Brazil) Nov.
09 (12 LT Brazil)

• TEC strongly increased on Nov. 09 (12 LT). No
  significant PPEF is identified at this time.

20
Nov. 06 (17 LT Brazil) Nov.
09 (17 LT Brazil)

• TEC strongly increased on Nov. 09 (17 LT). At
  this time occurs the strong PPEF event.

21
Nov. 06 (18 LT Brazil) Nov.
09 (18 LT Brazil)

• Anomalous development of EIA due to the PPEF.
  Intensified crests displaced to higher latitudes.
  

22
Nov. 06 (1830 LT Brazil) Nov. 09
(1830 LT Brazil)

• Anomalous development of EIA due to the PPEF.

23
Nov. 06 (20 LT Brazil) Nov.
09 (20 LT Brazil)

• Anomalous development of EIA due to the PPEF
  prevails until the end of Nov. 09.
• And on Nov. 10...

24
Nov. 06 (13 LT Brazil) Nov.
10 (13 LT Brazil)

• Anomalous TEC distribution on Nov. 10 (during
  partial recovery of vertical drifts).
• Negative phase of ionospheric storm is observed
  at mid-latitudes.
• Distribution of ionization is related to the
  decrease of O/N2 ratio at mid-latitudes.

25
Nov. 06 (19 LT Brazil) Nov.
10 (19 LT Brazil)

• Negative phase of ionospheric storm is still
  observed at mid-latitudes.
• This result prevailed during the whole day.

26

• Composition changes add to electrodynamics
  forcing.
• Nov. 08 Expansion at high latitudes causes
  decreasing in the O/N2 ratio resulting in TEC
  decreases at high to mid-latitudes.
• Nov. 10 Decrease of O/N2 ratio over
  mid-latitudes at South America region causing TEC
  decreases at this region.

From Mannucci et al. 2009 (JGR)
27
Final remarks

• EIA is inhibited on Nov. 07 even though the
  occurrence of PRE then it is probably due to the
  disturbed daytime vertical drifts (smaller
  compared to quiet time).
• Storm time TEC responses are well known on
• Nov. 08 (denoted by disturbance dynamo patterns),
  
• Nov. 09 (denoted by strongly developed EIA due to
  PPEF),
• Nov. 10 (denoted by the late negative phase of
  ionospheric storms over mid-latitudes).
• LISN added to RBMC (IBGE/Brazil) GPS receptors
  provide a good distribution over South America
  which is extremely important for this type of
  research at this region characterized by the SAMA
  and large declination differences.