1. Preeti Bhaneja Terry Bullett November 8, 2011
Detection of Spread-F and foF2 values using Digisonde and VIPIR instruments
Good Afternoon. My name is Preeti Bhaneja and I am from the CIRES group. My talk is about comparing solar cycle and seasonal variations of MSF using data from 4 different ionosonde stations.
Preeti Bhaneja
Terry Bullett
November 8, 2011 1

2. Index Introduction Data Analysis – methodology Data Presentation
Summary of ionosonde study at midlatitude regions.
Future Work
I will go over …. 2 2

3. Introduction
Ionospheric irregularities are temporal and spatial variations of the electron density lasting from a couple minutes to a few hours.
Midlatitude Spread F (MSF) and Equatorial Spread F (ESF) are fundamentally different due to their different magnetic geometry; horizontal magnetic lines at equatorial region and dip angle exceeds 45° at midlatitude regions.
ESF is generally caused by Rayleigh Taylor instability, bubbles and large plumes.
MSF is caused due to gravity waves causing ionospheric layers to move creating density perturbations.
How the MSF and ESF vary with different seasons will be shown in this presentation.
This is the map of North-America, showing the 4 ionosonde stations from where data has been obtained. All these sites vary geographically and have different latitudes, longitudes and declination angles. From East we have Wallops, Dyess, Boulder and Vandenberg.
The declination varies from -11 for Wallops to +14 for Vandenberg. 3 3

4. Data analyzed for these stations:
Introduction
Data analyzed for these stations:
Stations
Latitude
Longitude
Declination
Dip
Wallops Island, Virginia
37.95°
74.5°
-11°
65.3°
Dyess, Texas
32.4°
99.8°
6.9°
66.5°
Boulder, Colorado
40°
105.3°
10°
60.7°
Vandenberg, California
34.8°
120.5°
13°
58.7°
Jicamarca, Peru
12°S
76.8° 3° 1° 4 4

5. Data Analysis - Non-spread Ionogram
The O mode trace for an ionogram on a day with no spread F is shown -
This is an ionogram for a clear day, represented by a single trace. Each trace has multiple pixels, which are a function of frequency and height.
Midlatitude Non-Spread F event on 20 November 2004 at 6 UT.
Equatorial Non-Spread F event on 5 June 2010 at 2 UT.
Ionogram traces have a finite thickness due to the finite bandwidth of the ionosonde. This is an instrument effect. 5 5

6. Data Analysis - Ionogram for a spread event (Midlatitude Region)
Ionograms obtained for spread F show thickness or spread in the F region which is more than that obtained for a normal ionosphere.
A thickness or a spread in the trace observed in the ionogram, signifies a MSF event. It signifies a irregularity or instability in the ionosphere.
Midlatitude Spread F event on 1 November 2003 at 6 UT.
This is an ionosphere effect and signifies irregularities in the plasma densities in the ionosphere. 6 6

7. Data Analysis - Range & Frequency Spread F and foF2
Data Analysis - Range & Frequency Spread F and foF (Midlatitude Region)
The spread F observed on ionograms can be classified as range or frequency spread.
Range spread F* refers to
a condition in which there
are multiple echoes at
different ranges for
each frequency.
Frequency spread F* refers
to the case in which
multiple echoes at
different frequencies for each range.
*Definitions different than URSI
The MSF can be classified into range and frequency spread F.
Range spread F is …..
Frequency spread F is ….. 7 7

8. Data Analysis - Range & Frequency Spread F and foF2
Data Analysis - Range & Frequency Spread F and foF (Midlatitude Region)
The software analyzes the ionogram and determines the location of box 1 and box 2.
The height and width of box 1 is fixed.
The height and width of box 2 varies with the values of foF2 and hF2.
Edge detection is done on both the boxes to find the bottom side of box 1 and right side of box 2.
Large pixel counts in box 1 correspond to range spreading.
Large pixel counts in box 2 correspond to frequency spreading.
The threshold levels for boxes have been chosen by visually inspecting large number of ionograms.
Algorithms have been written to determine the location of box 1 and box 2.
Height and width….
Edge detection ….
Pixel counts are compared to set threshold values determined by random eyeballing of several ionograms. 8 8

9. Data Analysis - Ionogram for a spread event (Equatorial Region)
Different kinds of spread are observed on ionograms generated from Jicamarca data.
Range Spread,
Range and Frequency Spread
Spread in a form of big blob
The MSF can be classified into range and frequency spread F.
Range spread F is …..
Frequency spread F is ….. 9 9

10. Data Analysis - Spread F Measurement (Equatorial Region)
The location, height and width of box is fixed.
Large pixel counts in box correspond to spread event.
The threshold levels for boxes have been chosen by visually inspecting large number of ionograms.
Spread events have been quantified, and type of spread is not distinguished.
foF2 is not measured for spread cases due to lack of clear trace.
Algorithms have been written to determine the location of box 1 and box 2.
Height and width….
Edge detection ….
Pixel counts are compared to set threshold values determined by random eyeballing of several ionograms. 10 10

11. Data Analysis - foF2 Measurement (Equatorial Region)
Similar analysis as used for midlatitude region data, is used for equatorial region data.
The height and width of boxes 1 and 2 are changed for equatorial region.
Edge detection is done on both the boxes to find the bottom side of box 1 and right side of box 2.
foF2 is determined for non spread events.
Algorithms have been written to determine the location of box 1 and box 2.
Height and width….
Edge detection ….
Pixel counts are compared to set threshold values determined by random eyeballing of several ionograms. 11 11

12. Data Presentation - Data Description
Data processed :
Wallops, Dyess, and Vandenberg :
Boulder :
Jicamarca :
We consider only night-time data from 7 PM-5 AM LT.
The digisonde produces ionograms every 15 minutes, 24 hours a day : 44 ionograms/night .
The VIPIR produces ionograms every 1 minute, 24 hours a day : 720 ionograms/night .
Raw data were obtained in binary format and filtered and processed to generate ionograms for statistical analysis.
This was done for all 4 stations and data for 4 solar cycles have been processed and analyzed for midlatitude region.
Similar analysis with change in box locations have been done for Jicamarca data. 12 12

13. Data Presentation – Prototype Plot (midlatitude)
The spread F events, the onset times, duration and type of spread F are determined and
these values are stored in a text file.
Monthly plot shown for December 2009 using data from Wallops Island.
An example, monthly plot for Dec 2009 from Wallops is shown. It shows the MSF for each month.
Black bars are range spread F, and white bars are frequency spread F.
Similar plots have been obtained for all months for all years of available data for the 4 sites. 13 13

14. Data Presentation – Solar Cycle Variation (MSF)
Number of Spread F Days/Year for an entire solar cycle from No
Plot shows solar cycle variation. An unusual solar minimum. Black for range and white for frequency.
More MSF for solar min and less for solar max.
Most spread F events occur during solar minimum. 14 14

15. Data Presentation – Seasonal Variation (MSF)
Average Number of Spread F Days/Month for an entire solar cycle from
Seasonal pattern….a little tricky.
Wallops – more MSF during Oct-Dec and March
Dyess – more MSF during Dec-Jan
Boulder – more MSF during April- May and Sept
Vandenberg- more MSF during April-Sept and Dec. 15 15

16. Data Presentation – Prototype Plot (equatorial)
The spread F events, the onset time, duration and spread F are determined and these values are stored in a text file.
Monthly plot shown for July 2011 using data from Jicamarca.
An example, monthly plot for Dec 2009 from Wallops is shown. It shows the MSF for each month.
Black bars are range spread F, and white bars are frequency spread F.
Similar plots have been obtained for all months for all years of available data for the 4 sites. 16 16

17. Data Presentation – Seasonal Variation (ESF)
Average Number of Spread F Days/Month for
Seasonal pattern….a little tricky.
Wallops – more MSF during Oct-Dec and March
Dyess – more MSF during Dec-Jan
Boulder – more MSF during April- May and Sept
Vandenberg- more MSF during April-Sept and Dec. 17 17

18. Data Presentation – Comparison Plot (midlatitude)
The foF2 values determined for digisonde data and compared again ARTIST scaled values.
These values are also checked against manually scaled ionogram values.
The plot shows daily foF2 variation for March 16, 2010.
An example, monthly plot for Dec 2009 from Wallops is shown. It shows the MSF for each month.
Black bars are range spread F, and white bars are frequency spread F.
Similar plots have been obtained for all months for all years of available data for the 4 sites. 18 18

19. Data Presentation – Comparison Plot (midlatitude)
The foF2 values determined for both digisonde and VIPIR data are compared again ARTIST and ESIR scaled values.
These values are also checked against manually scaled ionogram values.
ESIR gives incorrect foF2 values for most of the time and even skips scaling at night-time hours.
The plot shows daily foF2 variation for August 10, 2011.
An example, monthly plot for Dec 2009 from Wallops is shown. It shows the MSF for each month.
Black bars are range spread F, and white bars are frequency spread F.
Similar plots have been obtained for all months for all years of available data for the 4 sites. 19 19

20. Data Presentation – Comparison Plot (equatorial)
The foF2 values determined for digisonde data and compared again ARTIST.
These values are also checked against manually scaled ionogram values.
The ARTIST attempts to scale even the spread ionograms where the foF2 is not visible or clear.
The plot shows daily foF2 variation for January 1, 2011.
An example, monthly plot for Dec 2009 from Wallops is shown. It shows the MSF for each month.
Black bars are range spread F, and white bars are frequency spread F.
Similar plots have been obtained for all months for all years of available data for the 4 sites. 20 20

21. Summary of ionosonde study for MSF
Solar Cycle Variation
Spread F occurs more frequently and lasts longer for solar min.
Seasonal Variation
The 4 stations show different seasonal variation patterns. This may be due to the local angle of declination.
Stations
Latitude
Longitude
Declination
Seasonal
(more MSF)
Wallops Island, Virginia
37.95°
74.5°
-11°
Vernal equinox, winter
Dyess, Texas
32.4°
99.8°
6.9°
Winter solstice
Boulder, Colorado
40°
105.3°
10°
Early summer, autumn equinox
Vandenberg, California
34.8°
120.5°
13°
Summer, winter solstice 21 21

22. Future Work
Differentiate ESF into quantity and quality….statistics on ESF occurrence and the type of spread F.
Determine a statistical study of ESF using digisonde and VIPIR data.
Determine the reasons for various kinds of spread in ESF.
Find a accurate way to measure foF2 value. 22

23. Acknowledgements
Work in cooperation with NGDC/NOAA.
QUESTIONS ???

24. Extra