Behavior of the total electron content over three stations of

the LISN zoneM. Mosert1, M. Gende 2 ,C. Brunini2, R.Ezquer3,4

1 Instituto de Ciencias Astronómicas, de la Tierra y del Espacio (ICATE)-CONICET- UNSJ, Avda. España 1512 (Sur), 5400 San Juan, Argentina, [E-mail: mmosert@icate-conicet.gob.ar]

2Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata- CONICET, La Plata, Argentina

3CIASuR, Facultad Regional Tucumán, Universidad Tecnológica Nacional, Tucumán, Argentina.

4 Laboratorio de Ionósfera, Dpto. de Física, FACET, UNT- CONICET, Tucumán, Argentina

LISN 2 Workshop 7-11 November, 2011, Sao Jose Dos Campos, Brazil

In this talk

We analyze the behavior of total electron contentusing data from Jicamarca (-12.0°S; 283°E); Tucuman (-26.9°S; 294.6°E) and El Leoncito, SanJuan (-31.5°S; 290.4°E). The database includes TEC measurements obtained from Digisondeobservations (ITEC) and GPS signals (GPSTEC). The day to day variability is analyzed.

Comparisonsbetween observations and the IRI –2007predictions are also done.

Data Used

Station Lat. Long. Years Rz12

Jicamarca -12.0° S 283° E 2001-2008 HSA-LSA

Tucuman -26.9°S 294.6°E 2008 LSA El Leoncito -31.5°S 290.4°E 2008 LSA

Representative months: January (summer), April (fall), July (winter) andOctober (spring)

Universal Time: 00 to 23

Data Used

ITEC: (h= 1000 km) obtained from digisonde ionograms using the true height inversion program NHPC (Reinisch and Huang, 1983; Huang and Reinisch, 1996)

GPSTEC: Vertical TEC derived from oblique GPS signals using La Plata Ionospheric Model, LPIM (Brunini et al, 2001)

IRITEC: (h =1000 km) obtained from IRI-2007 version (3 Topside options: IRI-2001, IRI-2001

corrected and NeQuick).

Our analysis

1. Behavior of GPSTEC over Jicamarca , Tucumán and El Leoncito, San Juan

2. Behavior of ITEC over Jicamarca

3. Analysis of topside electron density profiles

1. Behavior of GPSTEC over Jicamarca, Leoncito and Tucuman

Seasonal Variations – 2008 (Rz12= 2.8)

Fig. 1

0 2 4 6 8 10 12 14 16 18 20 220

5

10

15

20

25

30

35

40 El Leoncito (San J uan)

GP

ST

EC

[TE

CU

]

UT0 2 4 6 8 10 12 14 16 18 20 22

0

5

10

15

20

25

30

35

40J icamarca

GP

ST

EC

[TE

CU

]

UT

0 2 4 6 8 10 12 14 16 18 20 220

10

20

30

40

50Tucumán

GP

ST

EC

[TE

CU

]

UT

Summer Equinox Winter

Latitudinal Variations – GPSTEC - 2008 (Rz12= 2.8)

Fig. 2

0 2 4 6 8 10 12 14 16 18 20 220

5

10

15

20

25

30

35

40 January

GP

ST

EC

[TE

CU

]

UT0 2 4 6 8 10 12 14 16 18 20 22

0

5

10

15

20

25

30

35

40 April

GP

ST

EC

[TE

CU

]

UT

0 2 4 6 8 10 12 14 16 18 20 220

5

10

15

20

25

30

35

40 July

GP

ST

EC

[TE

CU

]

UT

0 2 4 6 8 10 12 14 16 18 20 220

5

10

15

20

25

30

35

40 October

GP

ST

EC

[TE

CU

]

UT

Jica Leon Tuc

2. Behavior of ITEC over Jicamarca

Seasonal Variations

Solar Activity Variations

Day to Day Variability

Comparisons between observations and IRI predictions

0 2 4 6 8 10 12 14 16 18 20 220

20

40

60

80

100 January

ITE

C[T

EC

U]

UT0 2 4 6 8 10 12 14 16 18 20 22

0

20

40

60

80

100April

ITE

C[T

EC

U]

UT

0 2 4 6 8 10 12 14 16 18 20 220

20

40

60

80

100July

ITE

C[T

EC

U]

UT0 2 4 6 8 10 12 14 16 18 20 22

0

20

40

60

80

100 October

ITE

C[T

EC

U]

UT

Median Mean

ITEC – Median or Mean values? Jicamarca 2002 (Rz12= 102)

F

Fig. 3

Jicamarca 2006 (Rz12=16)

0 2 4 6 8 10 12 14 16 18 20 220

10

20

30

40

50 JanuaryIT

EC

[TE

CU

]

UT

0 2 4 6 8 10 12 14 16 18 20 220

10

20

30

40

50

60 April

ITE

C[T

EC

U]

UT

0 2 4 6 8 10 12 14 16 18 20 220

10

20

30

40

50 July

ITE

C[T

EC

U]

UT

0 2 4 6 8 10 12 14 16 18 20 220

10

20

30

40

50October

ITE

C[T

EC

U]

UT

Median Mean

Fig. 4

-2 0 2 4 6 8 10 12 14 16 18 20 22 24

0

20

40

60

80

100ITEC - April 2002

ITE

C[T

EC

U]

UT

ITECMed Qup Qlo

0 2 4 6 8 10 12 14 16 18 20 220

20

40

60

80

100ITEC - January 2002

ITE

C[T

EC

U]

UT

ITECMed Qup Qlo

0 2 4 6 8 10 12 14 16 18 20 220

20

40

60

80

100ITEC - July 2002

ITE

C[T

EC

U]

UT

ITECMed Qup Qlo

0 2 4 6 8 10 12 14 16 18 20 220

20

40

60

80

100ITEC - October 2002

ITE

C[T

EC

U]

UT

ITECMed Qup Qlo

Fig 5 .Jicamarca- Medians and Quartiles- 2002 (HSA)

0 2 4 6 8 10 12 14 16 18 20 220

10

20

30

40

50ITEC - January 2006

ITE

C[T

EC

U]

UT

ITECMed Qup Qlo

0 2 4 6 8 10 12 14 16 18 20 22

0

10

20

30

40

50

60ITEC - April 2006

ITE

C[T

EC

U]

UT

ITECMed Qup Qlo

0 2 4 6 8 10 12 14 16 18 20 220

10

20

30

40

50ITEC - July 2006

ITE

C[T

EC

U]

UT

ITECMed Qup Qlo

0 2 4 6 8 10 12 14 16 18 20 220

10

20

30

40

50ITEC - October 2006

ITE

C[T

EC

U]

UT

ITECMed Qup Qlo

Fig 6. Jicamarca- Medians and Quartiles- 2006 (LSA)

0 2 4 6 8 10 12 14 16 18 20 220

10

20

30

40

50ITEC - January 2007

ITE

C[T

EC

U]

UT

ITECMed Qup Qlo

0 2 4 6 8 10 12 14 16 18 20 220

10

20

30

40

50ITEC - April 2007

ITE

C[T

EC

U]

UT

ITECMed Qup Qlo

0 2 4 6 8 10 12 14 16 18 20 220

10

20

30

40

50ITEC - July 2007

ITE

C[T

EC

U]

UT

ITECMed Qup Qlo

0 2 4 6 8 10 12 14 16 18 20 220

10

20

30

40

50ITEC - October 2007

ITE

C[T

EC

U]

UT

ITECMed Qup Qlo

Fig. 7 . Jicamarca- Medians and Quartiles- 2007 (LSA)

0 2 4 6 8 10 12 14 16 18 20 220

10

20

30

40

50

60

70

80

90

100 2006 (LSA)

ITE

C[T

EC

U]

UT

Fig. 8

0 2 4 6 8 10 12 14 16 18 20 220

10

20

30

40

50

60

70

80

90

1002002 (HSA)

ITE

C[T

EC

U]

UT

Jan April July Octu

Jicamarca ITECSeasonal Variations 2006 (Rz12= 16) – 2002 (Rz12= 102)

0 2 4 6 8 10 12 14 16 18 20 220

10

20

30

40

50ITEC - Jicamarca 2007 (LSA)

ITE

C[T

EC

U]

UT

Jan April July Octu

Fig. 9.

Fig. 10

0 2 4 6 8 10 12 14 16 18 20 220

20

40

60

80

100July

ITE

C[T

EC

U]

UT

0 2 4 6 8 10 12 14 16 18 20 220

20

40

60

80

100 January IT

EC

[TE

CU

]

UT

0 2 4 6 8 10 12 14 16 18 20 220

20

40

60

80

100 April

ITE

C[T

EC

U]

UT

0 2 4 6 8 10 12 14 16 18 20 220

20

40

60

80

100 October

ITE

C[T

EC

U]

UT

2006 2002

Jicamarca ITEC – Solar Activity Variations

Day to Day Variability

Variability indexes

Standard Deviations (SD)V%: Standard Deviations % = (SD/mean) * 100

Upper and lower quartilesCup= upper quartile/median Cup >1Clo= lower quartile/median Clo <1

Variability index: Cup-Clo

0 2 4 6 8 10 12 14 16 18 20 220,5

1,0

1,5

2,0

2,5

3,0

3,5

January

Ind

exe

s C

up

an

d C

lo

UT

0 2 4 6 8 10 12 14 16 18 20 220,5

1,0

1,5

2,0

2,5

3,0

3,5

July

Ind

exe

s C

up

an

d C

lo

UT

0 2 4 6 8 10 12 14 16 18 20 220,5

1,0

1,5

2,0

2,5

3,0

3,5 Abril

Ind

exe

s C

up

an

d C

lo

UT

0 2 4 6 8 10 12 14 16 18 20 220,5

1,0

1,5

2,0

2,5

3,0

3,5 Octubre

Ind

exe

s C

up

an

d C

lo

UT

Clo Cup

Fig. 11

Jicamarca - ITEC – 2006 (LSA: Rz12= 16)Variability indexes Cup and Clo

0 2 4 6 8 10 12 14 16 18 20 220,5

1,0

1,5

2,0

2,5

3,0

3,5 January

Ind

exe

s C

up

an

d C

lo

UT

0 2 4 6 8 10 12 14 16 18 20 220,5

1,0

1,5

2,0

2,5

3,0

3,5 July

Ind

exe

s C

up

an

d C

lo

UT

0 2 4 6 8 10 12 14 16 18 20 220,5

1,0

1,5

2,0

2,5

3,0

3,5 April

Ind

exe

s C

up

an

d C

lo

UT

0 2 4 6 8 10 12 14 16 18 20 220,5

1,0

1,5

2,0

2,5

3,0

3,5 October

Ind

exe

s C

up

an

d C

lo

UT

Clo Cup

Jicamarca - ITEC – 2002 (HSA: Rz12= 102)Variability indexes Cup and Clo

Fig. 12

Fig. 13

Jicamarca – ITEC – 2002 (HSA) / 2006(LSA)Variability index V%

0 2 4 6 8 10 12 14 16 18 20 220

20

40

60

80

100

120

140

160

180

200

220January

V%

UT

0 2 4 6 8 10 12 14 16 18 20 220

20

40

60

80

100

120

140

160

180

200

220April

V%

UT

0 2 4 6 8 10 12 14 16 18 20 220

20

40

60

80

100

120

140

160

180

200

220July

V%

UT0 2 4 6 8 10 12 14 16 18 20 22

0

20

40

60

80

100

120

140

160

180

200

220 October

V%

UT

2002 2006

Comparisons between ITEC and IRITEC predictions

Fig. 14

Jicamarca - IRITEC predictions 2006 Rz= 16

0 2 4 6 8 10 12 14 16 18 20 220

5

10

15

20

25

30

35

40 January

ITE

C[T

EC

U]

UT0 2 4 6 8 10 12 14 16 18 20 22

0

5

10

15

20

25

30

35

40 April

ITE

C[T

EC

U]

UT

0 2 4 6 8 10 12 14 16 18 20 22-10

-5

0

5

10

15

20

25

30

35

40 July

ITE

C[T

EC

U]

UT

0 2 4 6 8 10 12 14 16 18 20 22-10

-5

0

5

10

15

20

25

30

35

40October

ITE

C[T

EC

U]

UT

ITEC IRI-NeQ IRI-2001 IRI-2001corr

0 2 4 6 8 10 12 14 16 18 20 22

0

20

40

60

80

100April

ITE

C[T

EC

U]

UT

0 2 4 6 8 10 12 14 16 18 20 22

0

20

40

60

80

100July

ITE

C[T

EC

U]

UT

Jicamarca 2002 – ITEC / IRITEC

Fig. 15

0 2 4 6 8 10 12 14 16 18 20 220

20

40

60

80

100January

ITE

C[T

EC

U]

UT

3. Topside Electron Density Profiles

450

500

550

600

650

700

750

800

850

900

950

1000

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

UT 13.59

Nx105[cm-3]

h[k

m]

450

500

550

600

650

700

750

800

850

900

950

1000

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

UT 14.29

Nx105[cm-3]

h[k

m]

500

550

600

650

700

750

800

850

900

950

1000

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

UT 17.17

Nx105[cm-3]

h[k

m]

500

550

600

650

700

750

800

850

900

950

1000

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

UT 18.02

Nx105[cm-3]

h[k

m]

IRI01C IRINQ IRI01 ISR

Fig. 16

Jicamarca 13/11/2001 (Rz12= 111)

350

400

450

500

550

600

650

700

750

800

850

900

950

1000

-2 0 2 4 6 8 10 12 14 16

UT 14.00

Nx105[cm-3]

h[k

m]

350

400

450

500

550

600

650

700

750

800

850

900

950

1000

-2 0 2 4 6 8 10 12 14 16

UT 15.00

Nx105[cm-3]

h[k

m]

400

450

500

550

600

650

700

750

800

850

900

950

1000

0 2 4 6 8 10 12 14 16 18 20

UT 16.00

Nx105[cm-3]

h[k

m]

IRI01C IRINQ IRI01 ISR

Fig. 17

Jicamarca 11/06/2002 (Rz12= 102)

300

350

400

450

500

550

600

650

700

750

800

850

900

950

1000

0 2 4 6 8 10

UT 05.49

Nx105[cm-3]

h[k

m]

250

300

350

400

450

500

550

600

650

700

750

800

850

900

950

1000

0 2 4 6 8 10

UT 11.35

Nx105[cm-3]

h[k

m]

IRI01C IRINQ IRI01 ISR

Fig. 18

Jicamarca 15/04/2004 (Rz12= 42)

350

400

450

500

550

600

650

700

750

800

850

900

950

1000

0 2 4 6 8 10

UT 20.00

Nx105[cm-3]

h[k

m]

350

400

450

500

550

600

650

700

750

800

850

900

950

1000

0 2 4 6

UT 22.42

Nx105[cm-3]

h[k

m]

IRI01C IRINQ IRI01 ISR

350

400

450

500

550

600

650

700

750

800

850

900

950

1000

0 2 4 6

UT 23.13

Nx105[cm-3]

h[k

m]

Fig. 19

Jicamarca 28/06/2006 (Rz12= 16)

300

350

400

450

500

550

600

650

700

750

800

850

900

950

1000

0 2 4 6

UT 03.50

Nx105[cm-3]

h[k

m]

300

350

400

450

500

550

600

650

700

750

800

850

900

950

1000

0 2 4 6

UT 04.07

Nx105[cm-3]

h[k

m]

300

350

400

450

500

550

600

650

700

750

800

850

900

950

1000

0 2 4 6

UT 14.03

Nx105[cm-3]

h[k

m]

350

400

450

500

550

600

650

700

750

800

850

900

950

1000

0 2 4 6

UT 16.29

Nx105[cm-3]

h[k

m]

IRI01C IRINQ IRI01 ISR

Fig. 20

Jicamarca 30/06/2006 (Rz12= 16)

Summary

A study of the behavior of the total electron content (TEC) has been done using measurements obtained at Jicamarca, Perú (12.0 S; 283.0 E) and at Tucumán (26.9 S; 294.6 E ) and El Leoncito, San Juan (31.5 S; 294.6 E ), Argentina. The database includes TEC data derived from ground-based ionosonde data (ITEC) and from GPS satellite signals (GPSTEC). The diurnal, seasonal, solar activity variations and the day to day variability have been analyzed. Comparisons with the predictions of the last version of the International Reference Ionosphere model (IRI-2007) are also done.

The results show that the total electron content increases gradually from hours of minimum TEC (05-06 LT) in all the seasons reaching maximum values around midday. At sunset the TEC values begin to decrease reaching minimum values around sunrise. The TEC measurements generally show lower values in winter than in summer. The winter-summer differences are not so evident in the year of low solar activity. The largest daytime peak values are observed in the two equinoctial months.The IRI predictions generally overestimate the total electron content during nighttime and underestimate during daytime.Taking into account that the most contribution of TEC comes from the topside electron density profile, these results suggest that the discrepancies between IRI predictions and TEC measurements are due to the shape of the topside profile assumed by the model. In general NeQuick topside option follows better the ISR data.

Final Comments

Taking into account these results additional efforts are being done in order:

(a)To improve the modeling of the electron density profile.

(b) To advance in the formulation of a day to day variability model.

and some comments about the new ionosone installed at Tucuman.

B. San Martin

B. Belgrano(IAA)

Tucumán 2(CIASUR-FRT and UTN)

La Plata(GESA-UNLP)

Operative ionospheric stations

Tucumán (-26.9º S , 294.6º E) is placed near the Southern crest of the equatorial anomaly.

Since 1957 to 1987 ionospheric measurements were obtained with the analogue ionosonde of the Ionospheric Station of National University of Tucumán (UNT).

In 2007, within the Italian-Argentine collaboration supported by the Istituto Italo Latino Americano (IILA), an Advanced Ionospheric Sounder (AIS) built at the Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, was installed at the Upper Atmosphere and Radiopropagation Research Center (Centro de Investigación de Atmósfera Superior y Radiopropagación – CIASUR) of the Tucumán Regional Faculty of the National Technological University (UTN). That ionosonde is equipped with Autoscala, software able to perform an automatic scaling of the ionograms.

Figure 1 shows AIS, the antenna and an ionogram obtained at CIASUR.

Fig. 1. AIS, the antenna and an ionogram obtained at CIASUR

SF and ScintillationsSF and Scintillations

Tucuman received power from PRN 02 Noche del 07/11/07

20

25

30

35

40

45

25 25,5 26 26,5 27 27,5 28 28,5 29 29,5 30

UT

Rcv

d P

wr

(dB

)

1 1:30 2 2:30 UT

1:45 UT

Satélite 2

22:45 LT

Tucuman Recived Power from PRN 23Noche del 16/Abril/2008

20

25

30

35

40

45

50

27 27,1 27,2 27,3 27,4 27,5 27,6 27,7 27,8 27,9 28

UT

Rcv

d P

wr

(dB

)

3:45 UT

Satélite 230:45 LT

Tucuman Received Power from PRN 19Noche del 16/Abril/2008

20

25

30

35

40

45

50

27,5 28 28,5 29UT

Rcvd

Pw

r (d

B)

4:00 UT

Satélite 13

1:00 hs LT

First results

The data recorded by the AIS-INGV/Autoscala system installed at CIASUR showed ionograms with possible additional stratifications, different to E, F1 and F2 layers (Pezzopane et al 2007).

Fig. 2 shows an example were a F1.5 additionalstratification is observed.

Fig. 2. Ionograms recorded on 23 September 2007 from 14:05 to 14:45 UT by the AIS-INGV ionosonde installed at Tucumán, and autoscaled by Autoscala. The development and decay of a F1.5 additional stratification are highlighted using open circles. (From Pezzopane et al 2007)

First results

Range spread-F (RSF) and occurrence of “satellite” traces prior to RSF onset were also studied with AIS measurements.(Cabrera et al., 2010).

Fig. 3 shows a case where ST and RSF are observed.

Fig. 3. Sequence of ionograms recorded on 4 September 2007 showing (a) diffuse trace in the second order mode, (b) ST appearance adjacent to the low- frequency end of the first order mode, (c) RSF commencement, and (d) RSF fully developed. (From Cabrera et al, 2010)

Acknowledgments

We gratefully acknowledge to FAPESP for the financial support and to INPE for hosting this event in particular to Eurico di Paula.

The authors wish to thank to the staff of the JRO for the use of ISR data.

Obrigado!!