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Title: Powerpoint template for scientific poster


1
MIDLATITUDE SPREAD F P. Bhaneja1, G. D. Earle1,
R. L. Bishop2 (1) William. B. Hanson Center for
Space Sciences, University of Texas at Dallas,
(2) AeroSpace Corp.
ABSTRACT This research involves a case study of
Midlatitude Spread F (MSF) at Wallops Island
(37.8N, 75.5W) using ionosonde data. Software
has been developed in MATLAB to detect the edges
of the O-Mode traces, so that range and frequency
spreading can be objectively identified. A
separate algorithm is used to identify sporadic E
conditions. The intent is to determine the
seasonal variation of MSF over a complete solar
cycle from 1995-2005. The correlation between MSF
and geophysical parameters such as, Kp, Ap, DST,
Bz, F10.7 and sunspot number, and between
sporadic E and MSF is to be determined. An
initial study using data from 2001-2004 indicates
that MSF occurs most frequently over Wallops
Island in the autumn months.
PROGRAM EXPLANATION An autonomous computer
algorithm has been developed to identify range
and frequency MSF. Figure 3 shows how the
ionograms are processed and figure 4 shows a flow
chart describing the algorithm.
  • FUTURE WORK
  • Correlation between various geophysical indices
    and MSF
  • will be studied.
  • Correlation between sporadic E and midlatitude
  • spread F is also to be investigated.
  • A sample plot with all the indices, spread
    duration, time and
  • sporadic E is shown in figure 10.
  • Future work will involve assimilating the data
    from all
  • months in 1995-2005 into plots like that shown
    in
  • figure 10.
  • A booklet with collection of these plots will
    form the basis of
  • further research on obtaining a statistical
    analysis of
  • midlatitude spread F over Wallops Island, and
    may reveal
  • seasonal and solar cycle-related trends.

FIGURE 6. The plot shows the percentage of spread
days in each month for the year 2002.
FIGURE 7. The plot shows the percentage of spread
days for months of Jan-Aug for the year 2003.
INTRODUCTION Ionospheric irregularities are
temporal and spatial variations of the electron
density lasting from a couple minutes to a few
hours. In the lower latitudes of the F region of
the ionosphere, these irregularities are called
Equatorial Spread F. Occurrence of similar
irregularities in the midlatitude F region is
also called spread F, but at the midlatitudes the
mechanism of formation of spread F is not well
understood. Gravity waves are widely recognized
as a potential cause of these density
perturbations in the F region. Ionograms obtained
for spread F show thickness or spread in the F
region in figure 1, which is significantly more
than that obtained for a normal ionosphere as
shown in figure 2. The spread observed on the
ionograms can be classified as range or frequency
spread depending on whether the signal is spread
in range or frequency. This corresponds to spread
in depth and width respectively on an ionogram.
FIGURE 3. Midlatitude Spread F event. The plot
shows the boxes drawn to help identify both range
spread (box 1) and frequency spread (box 2).
FIGURE 8. The plot shows the percentage of spread
days in each month for the year 2004.
  • The weighted percent average for these four years
    is plotted
  • in figure 9.

FIGURE 10. Geophysical indices, spread
occurrence, duration, time and sporadic E are
shown for one month (November 2004).
FIGURE 9. The plot shows the weighted percent
average of spread days in each month for the
years 2001 -2004.
  • FUTURE EXPERIMENT DESCRIPTION
  • A rocket launch will be conducted in the fall of
    2006 to collect
  • data on midlatitude spread F and get more
    insight in this
  • instability.
  • The experiment will have both ground based and
    rocket based
  • measurements.
  • This will collectively form a quantitative
    analysis of the F
  • region radio propagation and TID environment
    with the in-situ
  • data giving a better picture and an in-depth
    look into the cause
  • of midlatitude spread F.

FIGURE 4. Flowchart for the code that identifies
spread ionograms, identifying both range and
frequency spread.
  • DATA PRESENTATION
  • Data for four years (2001- 2004) have been
    collected and
  • plotted.
  • The percentage of MSF occurrence for each month
    of
  • available data for these four years is plotted
    and shown in
  • figures 5 through 8.
  • A spreading event is classified as 1 or more
    ionograms with
  • spreading evident, where 15 minutes is the
    normal
  • ionogram cadence.

DISCUSSION As shown in figures 5-9, there is
substantial variability from month to month and
year to year in MSF occurrence. The fall season
appears to have the highest incidence of MSF,
which may be related to the relationship between
the local magnetic field and the nightime
terminator Earle et al., 2006. A geometry in
which these are aligned allows efficient electric
field mapping between conjugate hemispheres,
which may be important to the generation of MSF.
Alternatively, the high incidence of
thunderstorms in the spring and fall season at
Wallops Island may be related to enhanced MSF
probabilities. Finally, Bowman, 1994 has shown
that MSF is more prevalent in periods with low
F10.7 solar flux levels. This correlation will be
investigated in our future work, as will
correlations with sporadic E Cosgroove
Tsunoda, 2004.
FIGURE 1. Midlatitude Spread F event for a 15
minute sweep on 2 October, 2002. Only the O-Mode
trace is shown.
WORKS CITED 1. Bowman, G.G., Short-Term Delays in
the Occurrence of Mid-Latitude Ionospheric
Disturbances Following Other Geophysical and
Solar Events, J.Geomag. Geoelectr., 46,
297-309, 1994. 2. Cosgrove, R.B., and R.T.
Tsunoda, Instability of the E-F coupled nighttime
midlatitide ionosphere, J. Geophys. Res.,
doi10.1029/2003JA010243, 2004. 3. Earle, G.D.,
A.M., Mwene, and J.P. McClure, A global study of
nighttime midlatitude topside spread echoes,
submitted to J.Geophys. Res., 2006.
FIGURE 5. The plot shows the percentage of spread
days for months of Sep-Dec for the year 2001.
ACKNOWLEDGMENTS
This research has been
supported by NASA grant NNG04WC19G. The data for
all the plots have been provided by NGDC, SPIDR
and SPDF. We would also like to thank Terry
Bullett, Ray O Conkright, Rob Redmon for all
their help.
FIGURE 2. Same format as figure 1 for a normal
quiescent ionosphere on the same night.
Non-Spread Event.
FOR FURTHER INFORMATION Please contact
pxb049000_at_utdallas.edu. This poster is available
on-line at www.utdallas.edu/pxb049000
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