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RADC-TR-81-80 has been reviewed and is approved for publication. 


APPROVED: 7 y JfZ 

TERENCE J. ELKINS 

Chief, Propagation Branch 

Electromagnetic Sciences Division 


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c ^JOHN P. HUSS 



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REPORT DOCUMENTATION PAGE 


I i u 


RADC-TR-81-80 


*. TITLE 

VLF/LF REFLECTIVITY OF THE 
POLAR IONOSPHERE 
4 May —20 September 1380 


WMvjm 


READ INSTRUCTIONS 
BEFORE COMPLETING FORM 


RECIPIENT'S CATALOO NUMItN 


t. TVPC OF "(FORT A FCAlOO COVERED 

Scientific. Interim. 


I. RCRFORMINO ORO. REPORT HUNGER 


CT OR ORANT KUMGEACJ 


Robert P. Pagliarulo 
John P. Turtle 
John E. Rasmussen 


Ralph E. Gifford, 
SSgt, USAF 
Wayne I. Klem 


RCRFORMINO ORGANIZATION NAME ANO AOORCU 

Deputy for Electronic Technology (RADC/EEP) 
Hanscom AFB 
Massachusetts 01731 


II. CONTROLLING OFFICE NAME ANO AOORCU 


Deppty for Electronic Technology (RADC/EEP) 
Hanscom AFB 

Massachusetts 01731_ 


MOM I TORINO AOCNCY NAME * AOORBIS (It dltftmt tfm Controlling Office; 


STRlBUTlOK STATEMENT ft thlo Hopoti) 



It. REPORT DATE 

March 1981 


IS. NUMBER OF PAGES 

98 


IS. SECURITY CLASS. (•! th ft topoH) 

Unclassified 


Approved for public release; distribution unlimited. 


17. DISTRIBUTION ST. *4ENT (ol th* obcttocl ontorod In Block 20, It & I It ml from Koport) 


IS. supplementary .CTES 


IS. KEY VORDS fConfimi* on riMti* old* It nocoooory And Identity by Sloe* nuaiSorJ 

VLF propagation 
LF propagation 
t-ower ionosphere 


20. ABSTRACT (Contlnuo on rovotoo old* It nocoooory and Identify by block numbor) 

~~^ This report provides a summary of high-latitude ionospheric reflectivity 
data, as observed by the USAF high-resolution VLF/LF ionosounder operating 
in northern Greenland. Ionospheric reflectivity parameters, including reflec¬ 
tion heights and coefficients, are presented as a function of time of day. 
Riometer and magnetometer measurements of the polar propagation environ¬ 
ment are presented as supplementary data- 

A 


DO 1473 


\ Unclassified 

SECURITY CLASSIFICATION OF THIS PAGE (l»»«n Doto Tlnffd) 























fCCUMITV CUAtttFICATIOM Of TH|» rtHdlm But 


















9 


Preface 


The authors thank in particular Mr. Duane Marshall of Megapulse, Inc., for 
help with the equipment that made the measurements possible, and Mr. Bjarne 
Ebbesen of the Danish Meteorological Institute for the outstanding operation at 
Qanaq, Greenland. 

Appreciation is also extended to the Danish Commission for Scientific Research 
in Greenland for allowing these measurements to be conducted and to JorgenTaagholt 
and V. Neble Jensen of the Danish Meteorological Institute's Ionospheric Laboratory 
for their continued cooperation in this program. 


Accession For 

NTIS ~GRAJsI 
DUG TAB *X] 

Unannounced □ 
Justification_ 


X 


By- 

distribution/ 


Availability Codes 
Avail and/or 
Special 


Dist 


ft 


DTIC 

S ELECTE 

SEP 9 1981 

D 



3 










1. INTRODUCTION 7 

2. OBSERVED WAVEFORMS 9 

2. 1 Weekly Example of Individual Waveforms 9 

2. 2 Three-Dimensional Waveform Presentation 9 



3. REFLECTION HEIGHTS 10 

4. REFLECTION COEFFICIENTS 10 

5. SUPPLEMENTARY INFORMATION 11 

6. IONOSPHERIC DISTURBANCE DATA 11 

7. ADDITIONAL COMMENTS 12 

REFERENCES 95 


Illustrations 


1. 

Geometry of the Propagation Path 

8 

2. 

Examples of the Observed Waveforms 

9 

3. 

VLF/LF Reflectivity Data for the Polar Ionosphere, 

DAY 125 (4 May)-DAY 131 (10 May) 1980 

14 

4. 

VLF/LF Reflectivity Data for the Polar Ionosphere, 

DAY 132 (11 May)-DAY 138 (17 May) 1980 

18 


5 


turnout mm, 










\ 

s 



Illustrations 


5. VLF/LF Reflectivity Data for the Polar Ionosphere, 

DAY 139 (18 May)-DAY 145 (24 May) 1980 22 

6. VLF/LF Reflectivity Data for the Polar Ionosphere, 

DAY 146 (25 May) - DAY 152 (31 May) 1980 26 

7. VLF/LF Reflectivity Data for the Polar Ionosphere, 

DAY 153 (1 Jun) - DAY 159 (7 Jun) 1980 30 

8. VLF/LF Reflectivity Data for the Polar Ionosphere, 

DAY 160 (8 Jun) - DAY 166 (14 Jun) 1980 34 

9. VLF/LF Reflectivity Data for the Polar Ionosphere, 

DAY 167 (15 Jun)-DAY 173 (21 Jun) 1980 38 

10. VLF/LF Reflectivity Data for the Polar Ionosphere, 

DAY 174 (22 Jun) - DAY 180 (28 Jun) 1980 42 

11. VLF/LF Reflectivity Data for the Polar Ionosphere, 

DAY 181 (29 Jun)-DAY 187 (5 Jul) 1980 46 

12. VLF/LF Reflectivity Data for the Polar Ionosphere, 

DAY 188 (6 Jul) — DAY 194 <12 Jul) 1980 50 

13. VLF/LF Reflectivity Data for the Polar Ionosphere, 

DAY 195 (13 Jul) - DAY 201 (19 Jul) 1980 54 

14. VLF/LF Reflectivity Data for the Polar Ionosphere, 

DAY 202 (20 Jul) - DAY 208 (26 Jul) 1980 58 

15. VLF/LF Reflectivity Data for the Polar Ionosphere, 

DAY 209 (27 Jul) - DAY 215 (2 Aug) 1980 62 

16. VLF/LF Reflectivity Data for the Polar Ionosphere, 

DAY 216 (3 Aug) - DAY 222 (9 Aug) 1980 66 

17. VLF/LF Reflectivity Data for the Polar Ionosphere, 

DAY 223 (10 Aug) - DAY 229 (16 Aug) 1980 70 

18. VLF/LF Reflectivity Data for the Polar Ionosphere, 

DAY 230 (17 Aug) - DAY 236 (23 Aug) 1980 74 

19. VLF/LF Reflectivity Data for the Polar Ionosphere, 

DAY 237 (24 Aug) - DAY 243 (30 Aug) 1980 78 

20. VLF/LF Reflectivity Data for the Polar Ionosphere, 

DAY 244 (31 Aug) - DAY 250 (6 Sep) 1980 82 

21. VLF/LF Reflectivity Data for the Polar Ionosphere, 

DAY 251 (7 Sep) - DAY 257 (13 Sep) 1980 86 

22. VLF/LF Reflectivity Data for the Polar Ionosphere, 

DAY 258 (14 Sep) - DAY 264 (20 Sep) 1930 90 


6 





VLF/LF Reflectivity of the Polar Ionosphere 

4 May —20 September 1980 


1. INTRODUCTION 

This report provides a summary of high latitude ionospheric reflectivity data, 

as observed by the USAF's high resolution VLF/LF ionosounder operating in northern 
1 2 

Greenland. * As shown in Figure 1, the transmitter is located at Thule Air Base, 
Greenland (76° 33'N. Lat., 68° 40'W. Long. >, and the receiving site is 106 km 
north at the Danish Meteorological Institute's Ionospheric Observatory in Qanaq, 
Greenland (77° 24'N. Lat., 69° 20'W. Long., Geomagnetic Lat. 89° 06'N). The 
ionoaounding transmissions consist of a series of extremely short (approximately 
100 uaec) VLF pulses, precisely controlled in time, and radiated from a 130 m 
vertical antenna. At the receiving site, orthogonal loop antennas are used to sepa¬ 
rate the two polarisation components of the ionospherically reflected skywave signal. 
One antenna, oriented in the plane of propagation, is used to sense the groundwave 
and the transmitted or "parallel" polarization component of the skywave. The second 
loop, nulled on the groundwave, senses the converted or "perpendicular" polarization 
skywave component. The signal from each of the antennas is digitally averaged to 

(Received for publication 20 March 1981) 

1. Lewis, E.A., Rasmussen, J.E,, and Kossey, P. A. (1973) Measurements of 

ionospheric reflectivity from 6 to 35 kHz, J. Geophys, Res. fg; 19. 

2. Kossey, P. A., Rasmussen, J.E., and Lewis, E. A. (1974) VLF pulse iono¬ 

sounder measurements of the reflection properties of the lower ionosphere, 
Akademie Verlaq, COSPAR, July. 


7 





WEST LONGITUDE 



Figure 1. Geometry of the Propagation Path 

improve the signal-to-noise ratio of the individual received waveforms before they 
are recorded on magnetic tape. An example of the observed waveforms is given in 
Figure 2. where the "parallel" waveform (Figure 2a) consists of a groundwave propa¬ 
gated pulse, a quiet interval containing low level, off path groundwave reflections, 
followed by the first-hop parallel skywave component. The perpendicular waveform 
is shown in Figure 2b. 

Ionospheric reflection parameters are derived by computer processing of the 
ground and ionospherically reflected waveforms with allowance made for factors 
such as ground conductivity and antenna patterns (see Section 4). 


8 







******* 


-•MONOWAVE 


PARALLEL 5*Y WAVE 
COMPONENT 



0. "PARALLEL* WAVEPORM SENSED (V THE LOOP ANTENNA ORIENTED 
IN THE PLANE OP PROPAGATION 

vr PERPENDICULAR SKYWAVE 
\COMPONENT_ 

b. “PERPENDICULAR 1 WAVEPORM UNICO IT THE LOOP ANTENNA 
ORIENTED PERPENDICULAR TO THE PLANE OP PROPACATION 


| * . ' - i —" | . F 

100 200 MO 400 SO© 

TIME - MICROSECONDS 


Figure 2. Example of the Observed Waveforms 


Although the data are recorded about once per minute, for this report the wave¬ 
forms are averaged into 2-hr time blocks with the exception of the three-dimensional 
waveform presentations (Section 2.2). The resulting information is presented in a 
weekly format (Figures 3 through 22 as described below). 


2. OBSERVED WAVEFORMS 

2.1 Weekly Example of Individual Waveforms 

In part A of Figures 3 through 22, a set of averaged parallel and perpendicular 
waveforms is presented for the time block centered near local noon of the indicated 
day. Each of these waveforms is comprised of 256 digitally averaged points spaced 
2 /isec apart. In part B of the figures, the groundwave Fourier amplitudes are shown 
as a function of frequency. Although the data presented in parts C through L of the 
figures are generally limited to frequencies in the first, or principal, lobe of the 
spectrum, information at higher frequencies can be used when sufficient signal-to - 
noise conditions exist. There is, however, a frequency range around each spectral 
null where insufficient signal exists for measurements. 

2.2 Thrce-Duneiutonal Waveform Pr Mentation 

A three-dimensional display of the recorded || waveforms covering each weekly 
period is shown in Part R of each figure and the corresponding J_ waveforms are 
shown in Part S. For these plots the data has been averaged into 15-min time blocks. 















3. REFLECTION HEIGHTS 

The group mirror height (GMH) of reflection was obtained by determining the 
group delay of the skywave relative to the groundwave and attributing the time 
difference, by simple geometry (assuming a sharply bounded mirror-like ionos¬ 
phere) to a difference in propagation distance. As discussed in Lewis et al, 1 the 
group delay can be defined as the rate of change of phase with frequency. For the 
GMH data presented in this report, a finite frequency difference of 1.0 kHz was 
used, and the corresponding phase difference as a function of frequency for the 
groundwave and both skywave signals was obtained by Fourier analysis of the 
respective pulses. The GMH calculations took into account ground conductivity 
(10 mho/m is assumed), and the corrections of Wait and Howe were applied. 
Group mirror heights, obtained from the parallel and perpendicular waveforms, 
are plotted as a function of frequency in parts C and D of Figures 3 through 22. The 
GMH's are also presented as a function of time-of-day for the average frequency of 
16.5 kHz in figure parts E and I, The parallel GMH's in part E are shown along 
with an average reflection height for reference purposes. Each point of the refer¬ 
ence height is a weekly average, by time block, for the 7 -day period indicated. The 
corresponding perpendicular GMH's, part I of the figures, are also shown with the 
weekly average for comparison. Part G gives the average, by time block, for the 
daily parallel GMH data of part E, and part K gives the corresponding perpendicular 
GMH averages from the daily data of part I. 

4. REFLECTION COEFFICIENTS 

Assuming that the ionosphere acts as a "mirror" at the GMH, plane wave re- 

4 

reflection coefficients were obtained by comparing the ratio of the skywave Fourier 
amplitude at a specific frequency to that of the groundwave, taking into account 
wave spreading, earth curvature, ground conductivity, path lengths, andantcr.ia 
patterns including ground image effects. 

The reflection coefficient n R t | was obtained from analysis of the parallel sky- 
wave component and is plotted as a function of frequency in part C of Figures 3 
through 22. The )| R|| coefficient for 16 kHz is plotted as a function of time-of-day 
in part F along with the average of the indicated week for reference purposes. 

3. Wait, J. R., and Howe, H. H. (1956) Amplitude and Phase Curves for Ground- 

Wave Propagation in the Band 200 Cycles per Second to 50o Kilocycles ^ 

Kat. Bur, Stand. U. S. Circ. No. 674. 

4. Budden, K.G. (1961) Radio Waves in the Ionosphere, p. 85, Cambridge 

University Press, London. 


10 











From the perpendicular skywave pulse, the coefficient |j Ri^ was obtained and 
appears as a function of frequency in part D. The 16 kHzilRx is shown along with 
its reference in part J. Parts H and L present the average, by time block, of the 
dailyjjRji and u Rj^ data presented in parts E and J, respectively. 

For certain coefficient data points, plotted as asterisks (*), the reflection 
coefficient appears without a corresponding GMH. For these particular data, only 
the skywave-groundwave ratios could be obtained as the skywaves were too weak to 
provide reliable group delay information. The reflection coefficients were there¬ 
fore estimated using a nominal GMH of 80 km in the calculations. These estimated 
coefficient values are included in the averages presented in parts H and L. but the 
assumed heights are not used in the GMH averages shown in parts G and K. 


5. SUPPLEMENTARY INFORMATION 

For purposes of comparison and interpretation, certain supplementary data are 
presented. Part M of the figures shows the magnitude of the horizontal component 
of the polar magnetic field as recorded on a three-axis fluxgate magnetometer and 
part N presents 30-MHz riometer data, an indicator of D-region particle precipita¬ 
tion. These supplementary data were recorded at 30-sec intervals by RADC/EEP 
at Thule AFB; the curves represent the average of 10-min periods. The solar 
zenith angle is given in part O of Figures 3 through 22 for the indicated mid-week date. 


6. IONOSPHERIC DISTURBANCE DATA 


During the period covered by this report, solar activity continued at a low level. 
The strongest event recorded occurred on 17 July (DAY 199). Although no riometer 
data were available for plotting, it is known that absorption reached 2 dB on 18 July 
(DAY 200). The effects of other smaller energetic particle events can be seen in 
the data beginning on the following dates. None of these events produced more than 
0. 5 dB riometer absorption. 


7 June (DAY 159, Figure 7) 

21 June (DAY 173, Figures 9-10) 
29 June (DAY 181, Figure 11) 

6 July (DAY 188,( Figure 12) 


17 July 
6 Aug 
14 Aug 
31 Aug 


(DAY 199, Figures 13-14) 
(DAY 219, Figure 16) 
(DAY 227, Figures 17-19) 
(DAY 244, Figure 20) 


The transient effects of Sudden Ionospheric Disturbances (SID) can be seen in many 
of the three-dimensional waveform plots. These short-lived events were particu¬ 
larly evident during the week 11 May (DAY 132) — 17 May (DAY 138), Figure 4. 


11 








During ionospheric disturbances when enhanced ionization causes a lowering 
of the reflection heights, the skywave moves closer to the groundwave and can 
merge with constant off-path groundwave reflections (described in Section 1, Intro¬ 
duction). During these periods, the off-path reflections are computer subtracted 
from the waveforms to avoid contamination of the skywa”e data. This subtraction 
technique was used in the parallel and perpendicular waveform data for the weekly 
periods beginning on: 

DAY 153 (Figure 7) DAY 209 (Figure 15) 

DAY 167 (Figure 9) DAY 216 (Figure 16) 

DAY 174 (Figure 10) DAY 223 (Figure 17) 

DAY 181 (Figure 11) DAY 230 (Figure 18) 

DAY 188 (Figure 12) DAY 237 (Figure 19) 

DAY 195 (Figure 13) DAY 244 (Figure 20) 

DAY 202 (Figure 14) 

7. ADDITIONAL COMMENTS 

5-21 

This report is one of a series. Comments and suggestions for improving 
its usefulness should be addressed to the Propagation Branch (EEP) Electro¬ 
magnetic Sciences Division, Deputy for Electronic Technology (RADC/EEP), 

22 

Hanscom AFB. Massachusetts 01731. A report has been published which gives 

a detail description of the VLF/LF propagation disturbances produced by energetic 

4-14 

particle events during the period 1974 - 1977. 

(Because of the large number of references cited above, they will not be listed here. 
See References, page 94.) 


12 

























Figure 3. VLF/LF Reflectivity Data for the Polar Ionosphere. DAY 125 (4 May)—DAY 131 (10 May) 1980 (Cont) 













Figure 3. VLF/LF Reflectivity Da 
DAY 125 (4 May) - DAY 131 (19 Ma 
Part S. J. Waveform Display 


17 


for the Polar Ionosphere 
1980 (Cont) 


















I? 



19 


Figure 4. VLF/LF Reflectivity Data for the Polar Ionosphere. DAY 132 (11 May) - DAY 138 (17 May) 1980 (Cont) 



















Figure 4. VLF/LF Reflectivity Data for the Polar Ionosphere 
DAY 132 (11 May)-DAY 138 (17 May) 1980 tCont) 

Part R. i| Waveform Display 













•CCM M»* 


4 


200 500 

TiW 



figure 4, VLP/DF Reflectivity Data for the Polar ionosphere, 
DAY 132 (11 May) — DAY 138 (17 May) 1980 (Cont) 

Part S, X Waveform Display 


2 

























•e 5. VLF/L.F Reflectivity Data for the Polar Ionosphere, DAY 139 (18 May) — DAY 145 (24 May) 1980 (Cont) 


















(UfltH '«»*>*. 




Figure 5. VLF/LF Reflectivity Data for the Polar Ionosphere 
DAY 139 (18 May)-DAY 145 (24 May) 1980 (Cont) 

Part R, || Waveform Display 
























igure 6. VLF/LF Reflectivity Data for the Polar Ionosphere, DAY 146 (25 May) — DAY 152 (31 May) 1980 
















































le P< 









































r2rSjg£~ 





















iwnurtM Vomiiiw <«• 


Js I 




1NSI9JJ4M3 Ul43)li3V ’¥• 


mi in am i m«i 


mi tit am i mi 


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_«■** *<p « 



* " ,l iui»"wonft“owi£i 0 Jnow >' 0 


mi w m i mi 


mi III 1M I mi 




OE'O OZ’O 01-0 

(i-0IX)30fundM« 


*U*U» 


igure 8. VLF/LF Reflectivity Data for the Polar Ionosphere. DAY 160 (8 Jun) — DAY 166 (14 Jun) 1980 







































Figure 8. VLF/LF Reflectivity Data for the Polar Ionosphere, 
DAY 160 (8 Jun) - DAY 166 (14 Jun) 1980 (Cont) 

Part S. Waveform Display 


‘'rt; 























VLF/LF Reflectivity Data for the Polar Ionosphere, 

























































gure 10. VLF/LF Reflectivity Data for the Polar Ionosphere, DAY 174 <22 Jun) DAY 180 (28 Jun) 1980 (Cont) 




















45 


































200 500 

u«f Mjctoyaam 


Figure 11. VLF/LT Reflectivity Data for the Polar Ionosphere 
DAY 181 (29 Jun) — DAY 187 (5 Jul) 1980 (Cont) 

Part S. I Waveform Display 



































Figure 12. VLF/LF Reflectivity Data for the Polar Ionosphere, 
DAY 188 (6 JuD-DAY 194 (12 Jul) 1980 (Cont) 

Part R. || Waveform Display 












IDCAt W»N — 



6 


”1 - 1 - 1 

kOO 200 500 

tiuf UKMWCCkOS 


Figure 12. VLF/LF Reflectivity Data for the Polar Ionosphere 
DAY 188 (6 Jul)-DAY 194 (12 Jul) 1980 (Cont) 

Part S. X Waveform Display 













t>. Ctour Mltltot uni CTI OK HEIGHTS AND ASSOC* MtO AC Hi HI ON COCffl CHVS f *0* CULM S«1W DATA 

Figure 13. VLF/LF Reflectivity Data for the Polar Ionosphere, DAY 195 (13 Jul) — DAY 201 (19 Jul) 1980 






Figure 13. VLF/LF Reflectivity Data for the Polar Ionosphere. DAY 195 (13 Jul) - DAY 201 (19 Jul) 1980 (Cont) 




























I " -- T-1-1-T" 

0 100 200 SOO 400 

HM uutQUCWl 


Figure 13. VLF/LF Reflectivity Data for the Polar Ionosphere, 
DAY 195 (13 Jul)-DAY 201 (19 Jul) 1980 (Cont) 

Part S. J.Waveform Display 


57 







(Ml IHUt I •»> 

o 



Mil Ml M I »•* 







14. VLF/LF Reflectivity Data for the Polar Ionosphere, DAY 202 (20 Jul) — DAY 208 (26 Jul) 1980 (Cont) 

























Figure 14. VLF/LF Reflectivity Data for the Polar Ionosphere 
DAY 202 (20 Jul) - DAY 208 (26 Jul) 1980 (Cont) 

Part R. || Waveform Display 



















































0 


~l -1-—I— 

>00 ZOO 500 

111* - *UCSW0A3> 


Figure 15. VLF/LF Reflectivity Data for the Polar Ionosphere, 
DAY 209 (27 Jul) - DAY 215 (2 Aug) 1980 (Cont) 

Parts. J.Waveform Display 






5 










<j¥«gS &***»&&£ 


Figure 16. VLF/LF Reflectivity Data for the Polar Ionosphere, DAY 216 (3 Aug) DAY 222 (9 Aug) 1980 (Cont) 



















VJHMMAtMUUNtt 



0 


IIV* »W(S0il(‘JK6> 


Figure 16. VLF/LF Reflectivity Data for the Polar Ionosphere 
DAY 216 (3 Aug) - DAY 222 (9 Aug) 1980 (Cont) 

Part S. 1 Waveform Display 


































6 


“i-1 i- 

WO 200 WO 4 

IU* • MdWCOttl 


Figure 17. VLF/LF Reflectivity Data for the Polar Ionosphere, 
DAY 223 (10 Aug)-DAY 229 (16 Aug) 1980 (Cont) 

Part S. XWaveform Display 


































Figure 18. VLF/LF Reflectivity Data for the Polar Ionosphere 
DAY 230 (17 Aug) - DAY 236 (23 Aug) 1980 (Cont) 

Part R. || Waveform Display 


































Figure 19. VLF/LF Reflectivity Data for the Polar Ionosphere, DAY 237 (24 Aug) — DAY 243 (30 Aug) 1980 (Cont) 











tfCAl WA 



0 


Figure 19. VLF/LF Reflectivity Data for the Polar ionosphere, 
DAY 237 (24 Aug) - DAY 243 (30 Aug) 1980 (Cont) 

Part R. 11 Waveform Display 


80 























le P< 













83 


CftOOP «IRR(* KIO-TS W * ) W fSOW PfftXttlCUM WY**Vf MTA ' * #vt RACC it.Aliraw.»««NDICUAB.om 














Ilk* Wfk9ttU»C* 


Figure 20. VLF/LF Reflectivity Data for the Polar Ionosphere, 
DAY 244 (31 Aug) - DAY 250 (6 Sep) 1980 (Cont) 

Part S. J_ Waveform Display 









21. V LB'/ LF Reflectivity Data for the Polar Ionosphere, 


























Figure 21, VLF/LF Reflectivity Data for the Polar Ionosphere 
DAY 251 (7 Sep) - DAY 257 (12 Sep) 1980 (Cont) 

Part S, J_ Waveform Display 




























0 


200 500 

fiw VknO'“i«W 


Figure 22. VLF/LF Reflectivity Data for the Polar Ionosphere 
DAY 258 (14 Sep) - DAY 264 (20 Sep) 1980 (Cont) 

Part R. 11 Waveform Display 




















t 


References 


1. Lewis, E.A., Rasmussen, J.E., and Kossey, P. A. (1973) Measurements of 

ionospheric reflectivity from 6 to 35 kHz, J, Geophys. Res . ,£8:19. 

2. Kossey, P. A., Rasmussen, J.E., and Lewis, E. A. (1974) VLF pulse iono- 

sounder measurements of the reflection properties of the lower ionosphere, 
Akademie Verlaq, COSPAR, July. 

3. Wait, J. R., and Howe, H. H. <1956) Amplitude and Phase Curves for Ground- 

Wave Propagation in the Band 200 Cycles per Second to 500 Kilocycles, 

Nat.' Bum Stand. U.S. Circ. No. 574. 

4. Budden, K.G. (1961) Radio Waves in the Ionosphere , p. 85, Cambridge 

University Press, London,' 

5. Rasmussen, J.E., McLain, R.J., Capt, USAF, and Turtle, J.P, (1976) 

VLF/LF Reflectivity of the Polar Ionosphere, 19 January — 2 March 1975, 

APCRL-TB-'7S-0045, ADA022674. 

6. Rasmussen, J.E., McLain, R.J., Capt, USAF, and Turtle, J.P. (1976) 

VLF/LF Reflectivity of the Polar Ionosphere, 2 March—3 May 1975, 

RADC-TR-76-146, AD A026465, 

7. Rasmussen, J.E., McLain, R.J., Capt, USAF, Turtle, J.P., and 

Klemetti, W. 1. (1976) VLF/LF Reflectivity of the Polar Ionosphere, 

4 May —5 July 1975 , RADC-TR-/6-270, AD A034023. 

8. Rasmussen, J.E., McLain, R.J., °apt, USAF, Turtle, J.P., and 

Klemetti, W. I. (1976) VLF/LF Reflectivity of the Polar Ionosphere, 

20 July - 20 September~l97 5, RADC-TR-V6-327, ADA036913, 

9. Rasmussen, J.E., McLain, R.J., Capt, USAF, Turtle, J.P., and 

Klemetti, W.I. (1976) VLF/LF Reflectivity of the Polar Ionosphere, 

21 September — 3 January 1976, RADC-TR-76-378, AD A037794. 

10. Rasmussen, J.E., Turtle, J, P., Pagliarulo, R.P., and Klemetti, W.I. (1977) 
VLF/LF Reflectivity of the Polar Ionosphere, 4 January —3 July 1976, 

RADC-TR-77-68, AD A040920.- 


95 






References 


11. Rasmussen, J.E., Turtle, J.P., Pagliarulo, R.P., and Klemetti, W. I. (1977) 

VLF/LF Reflectivity of the Polar Ionosphere, 1 August 1976 — 1 January 1977, 
H7fDc^ir^7^T4TrwM?io , 5o-:— -- , 

12. Rasmussen, J.E., Turtle, J.P., Pagliarulo, R.P., and Klemetti, W. 1. (1977) 

VLF/LF Reflectivity of the Polar Ionosphere, 2 January —30 April 1977, 

R'ADC-TR -77 -T5TTATyiV(r47m- 

v 

13. Rasmussen, J.E., Turtle, J.P., Pagliarulo, R.P., and Klemetti, W. I. (1977) 

VLF/LF Reflectivity of the Polar Ionosphere, 1 May— 3 September 1977, 

IFADCTin ’T^rA'DiVOSms;- 

14. Pagliarulo, R. P., Turtle, J. P., Rasmussen, J.E., and Klemetti, W. I, (1978) 

VLF/LF Reflectivity of the Polar Ionosphere, 4 September — 31 December 1977, 
rAdC-TR- 78-95, ADA0e09l8. 

15. Pagliarulo, R. P., Turtle, J, P., Rasmussen, J.E., and Klemetti, W. I. (1978) 

VLF/LF Reflectivity of the Polar Ionosphere, 1 January —22 April 1978, 

RA'DC -TR^7 8 - IBB," A D“SU5253^- 

16. Pagliarulo, R. P., Turtle, J, P., Rasmussen, J.E., Cooley, R. L., TSgt, and 

Klemetti, W. I. (1979). VLF/LF Reflectivity of the Polar Ionosphere, 

23 April — 2 September"T978 , RADC-TR-79'~100,' ADA074782.- 

17. Pagliarulo, R.P., Turtle, J. P., Rasmussen, J.E., Cooley. R. L., TSgt, and 

Klemetti, W. I, (1979) VLF/LF Reflectivity of the Polar Ionosphere , 

3 September—30 December 1976, RaDC-TR-79-178. 

18. Pagliarulo, R. P., Turtle, J. P., Rasmussen, J.E., Cooley, R. L., TSgt, and 

Klemetti, W. I. (1979) VLF/LF Reflectivity of the Polar Ionosphere, 

31 December-5 May 1979, RADC-TR-79-273, AD A083240. 

19. Pagliarulo, R. P., Turtle, J. P., Rasmussen, J.E., Cooley, R. L., TSgt, and 

Klemetti, W. I. (1980) VLF/LF Reflectivity of the Polar Ionosphere, 

6 May — 1 September 1979 , KADC-Tk- 80-12, AD Ao9l09l. ~ 

20. Pagliarulo, R. P., Turtle, J. P., Rasmussen, J.E., and Klemetti, W. I. (1980) 

VLF/LF Reflectivity of the Polar Ionosphere, 2 September— 22 December 1979, 

TTADC^nrwnHs:- 

21. Pagliarulo, R. P., Turtle, J. P., Rasmussen, J.E., and Klemetti, W. I. (1980) 

VLF/LF Reflectivity of the Polar Ionosphere, 6 January —3 May 1980, 

HAD'C-Tir-80 -29S7"Ar "A094104.- -- 

22. Turtle, J.P., Rasmussen, J.E., Klemetti, W. I. (1980) Effects of Energetic 

Particle Events on VLF/LF Propagation Parameters, 1974-1977, 

RADC-TR-80-307. 




% 


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\ 

\ MISSION 5 

\ of \ 

*> Rome Air Devebjrment Center £ 

\ RAVC plant and executes KM With, development, tut and i 

• 4e£ec ted acquisition programs in Support: of Command, Control 5 

$ Communications and Intelligence (C 3 I) activities. Technical ? 
% and engineering support within areas of technical competence C 
s -ts provided to ESV Program Offices (POs) and other ESV § 

^ elements. The principal technical mission areas are & 

k communications, electromagnetic guidance and control, sua - ss 
j vcillance of ground and aerospace objects, intelligence data 

• collection ana handling, information system technology, v 

t ionospheric propagation, solid state sciences, microwave 
6 physics and electronic reliability, maintainability and 
\ compatibility. 




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