MASSACHUSETTS INSTITUTE OF TECHNOLOGY
LINCOLN LABORATORY
MILLSTONE HILL THClMSON SCATTER RESULTS FOR 1965
J. V. EVANS
Group 21
TECHNICAL REPORT 474
8 DECEMBER 1969
This document has been approved for public release and sale;
its distribution is unlimited.
LEXINGTON
MASSACHUSETTS
The work reported
a center
in this
for research
wi[h the support
IAF 19(628)-5167.
ducument
operated
O( the
Department
This report may be reproduced
E
Perm]ss\on
was performed
by Massachusetts
of
to satisfj’
lsgiven
the
needs
todestroy
at Lincoln
Institute
Air Force
Labomtory.
of Tec’hnolo%b
under
of U. S. Government
Contract
agmi,s.
this document
ii
—,.—.
i:
.. .
,...
ABSTRACT
This
report
presents
F-region
electron
observed during the year 1965 at
the
densities,
and electron
and ion tempermures
Millstone Hill Radar Observatory
by the UHF Thomson (incoherent) scatter radar.
The measurements
(42. 6°N. 71. 5“W)
were made over
48-hour periods that were LIsually scheduled to include the International Geophysical
World days near the center of each month.
occurred
Geomagnetic storm sudden commencements
during m,. of tbe observing periods,
but do not appear to have given rise to
On the other band, measuremems
marked variation of the densities or mmperat.rcs.
made during the progress of a major storm (15-19
pared
with tbc behavior obscrv.d
magnetically
served
quiet,
in 1964.
in the following
1965) exbihit large .banses c.m -
month.
The remaining muntbs were
and the density and temperature behavior were similar
to those ob-
Millstone is a midlatitucfe station exhibiting a characteristic
and ‘csummer” dayTime densify variation.
rapidly
June
around equinox,
thermal structure.
The transition befween these tio iypes occurs
without any corresponding
seasonal change in the F-region
Current ideas concerning tbc mechanisms responsible
othe,r features of diurnal and seasonal variations arc discussed.
Accepted for the Air Force
Franklin C. Hudson
Chief, Lincoln Laboratory Office
“winter”
for this and
CONTENTS
111
Abstract
I,
II,
1
INTRODUCTION
2
EQUIPMENT
2
A,
General
B.
The l+~cording
C.
Spectrum
3
System
Analyzer
5
System
8
111. CIIMERVATIONS
IV.
DATA
A.
.
V.
F-Region
Critical
C.
Electron
and [on Temperatures
(PriOrto.ltllY)
D.
Electron
and Ion Temperatures
(July and I.ater)
RESULTS
C,
VIII.
13
Density
Diurnal
FOR
DENSITY
Plots
and Nighttime
N(h) Profiles
AND
A.
Mean Daytime
B.
Discussion
MAGNETIC
Au*st
B.
June
C.
Discussion
SUMMARY
ION TEMPERATURES
and Nighttime
DISTURBANCE
A.
13
i5
i6
16
‘. 16
16
Discussion
ELECTRON
References
PTOfile
ELECTRON
13. Mean Daytime
VII,
9
Frequency
13. Electron
A.
VI.
9
RED[JCTION
Te and Ti Profiles
EFFECTS
and September
30
30
42
43
43
43
AND
47
CONCLUSIONS
47
49
MILLSTONE
L
HILL THOMSON SCATTER
RESULTS
FOR 1965
INTRODUCTION
This
report
the Thomson
71,50 W).
presents
Earlier
f963i
in relation
to
of special
*0
call,v clisturb ccl conditions.
presented
the
results
The large
reports
volume
publication
that many users
period
Vurther,
transcribing
ing toward
the results
Section
tables
of changes
hcncc,
of these
reports,
the
presenting
h;Iw
for
pub-
betw
of these meas-
of the I.-region.
or have
program
is a continuing
precludes
In this report,
althmgh
graphically,
However,
a single
about 100 entries,
to haw
the graphs
problem
The remedy
for analysis.
figure
and thereby
the major
in computer-usable
*e
we .O,1-
reeognize
corcring
a 24-hour
Pro,ride an in~mense
a“ailable,
even if tal,lcs
encounterecl,
pscsumably
form,
its
ncwd for technical
our results
would prefer
users
there
may be made available.
to the instrumentation
and quantity of the results,
IV is a brief
review
were
sults for electron
density
part of the sunspot cycle,
could be averaged
and ionospheric
to produce
i.e.,
that of
lies in being able
and we are currently
The rqmrtz
both the L’IIF and L-band
made during
the activity
v?ork-
that have influenced
respectively.
in Sec.s.11 and 111.
and \,l present
.Altbough the year
taken during disturbed
in 1964 included
a summary
results
systems.
The results o[tbe L-band
Ii
been reported,
and will not be included here.
1
—-----
re1965
low that most of the data
Sec. VII1 provides
obtained
radar
while Sees.b”
was sufficiently
Some data were
Finally,
ccmtaining the results
1965 have already
procecl”res,
temperatures,
in Sec. VII.
(steerable)
procedure,
made during f965 ancf are described
monthly- means.
and this is discussed
conclusions,
and observing
of the data- redaction
was on the rising
however,
and the means by which
and have presented
the s,ynoptic me8surenlcnt
would not solve
to particular
versions
1965 using
(426” N,
this end.
A number
the quality
each having
the data into a computer
to transmit
during
journals;
most users
Finally,
system
and temper atur’cs,
for the behavior
the,,, i. tal~ular fOrm.
24 tables,
the radar
for the: year
Massachusetts
s such as those made during an eclipse 9 or ma~neti-
of presenting
would prefer
could be included.
theories
in which all the results
begun earlier
Westforcl,
“ne summer and one equinoct ial month,
5-8
have discussed the significance
papers
of data gathered
can represent
sawing in space.
densities
observstio.
in the scientific
sLIcii as this,
tinue the practice
have described
accepted
currently
of the “F-region
Ilill,
and 1964.2 Shorter
for one winter,
3,4
.jourmds.
Other
in scientific
studies
at Millstone
ionospheric
only results
urements
complete
of synoptic
radar
in this series
to determine
ohtiained in the years
each year
lished
scatter
reports
it can be employed
results
the results
[incoherent)
periods,
and some
obtained
using
observations
II.
EQfJfPMENT
A.
General
The radar
summarizes
“d
equipment cmplo>-cci in these observations
the parameters
significantly
the recording
different
of the \-ertic ally directed
in f 965 than from
of signals
at 11,’on magnetic
P.rrnittcda cycle of measurements
sigm+ls reflected
approximately
present
from
90 minutes.
in Sc’c. 13below
While
valuable
an observing
effort,
2} weeks to process,
A second
mit both halves
not recognized
major
,1 major
syst?m
proved
change made in i 965 was
To explore
has’ not previously
recorded
that could be g:lthcred
ciuring a single
to he analj%ed.
4&hour
run usually
tedious
Polarization
Circular
of the spectrum
extract
Transmitter
pulse lengths
Pulse repetition
Rece!ver
fixed parabola
1600 mz
power
frequency
bandwidths
2.5 MW
O. 1-, 0.5-,
and l. O-msec pulses used
50 Hz
25 kHz for O. I-msec pulses
16 kHz for 0.5-
ond 1. O-msec pulses
40 k Hz for recording
System
temperature
Post-detector
integration
‘300” K (monitored
-20
dB
analyzer
the parameters
~f! MHZ
Peak transmitter
required
Z to
to handle.
PARAMETERS OF THE UHF VERTICALLY POINTING
THOMSON SCATTER RADAR
70-m-diameter
of
it was possible
This was done in a manner
to subsequently
Antenna
cillring
of a considerable
TABLE I
Frequency
!, C!
compnncnls
I..ortunately,
improperly.
but only at the expense
was also extremely
macle it difficult
aperture
of the
in a way that was not immediately
change during 4965 was the reconstruction
Effect;ve
“[his scheme
the spectra
been described,
to be one of the lCSS reliable
processing,
so that the scheme
at the time,
I
without making use 0[ this would have taken
the amount of information
s~stcm
spectrum
Table
these were
of its functions.
by computer
of the signal
radar;
pln3-back ancl analysis.
1966-i 968) it malfunctioned
The tapes
previously.$
scatter
in 30 minutes,
amounts of data to he analyzed
the information
amount of extra
outline
(during
large
of interest
increasing
the rccorcii”g
I.atcr
obvio~] .?, causing
to retrieve
a brief
years,
tape for later
Since the rccorclimg
in greatly
period,
the equipment.
previous
to he completed
all the altitudes
has been described
L-IIF Thomson
system
continuous
y)
which.
to Perthough
of electron
and ion temperatures
ing on the results,
from
we describe
The Recording
B.
The receiver
in the Millstone
vided a bandwidth
Figure
(MINCOM
of 250 kHz,
on a iO~-inch
standard
coincident
had seven
channels
of the recording
was employed
separate
the required
channels,
the
band,
purposes,
pulse,
reference
signals
constructed
tone,
(3) WWV timing
were
40-kHz
provided
ther-eafte r.
reference
pro-
two complete
This filter
and (5) start/ 8top signals.
IF and i 00-kHz
some redundancy
signals.
sine-wave
a !. 5-MHz
this recorder
data (i. e.,
and a rapid falloff
three
(2) the spectrum
we employed
A carefully
the recorded
(1) a 100-kHz
At this point,
at 30 ips,
an hour’s
edge of each transmitter
for identification
at IF,
arrangement.
to band-limit
we also recorded
with the leading
to provide
of +-inch
superheterodyne
and integration,
operated
tape (3 M-98i ).
flat to within AI dB over
announcements
the signals
When
us to record
a response
to the wanted IF signals,
to record
reel
7-pole
pulses
has some bear-
is a multiple
at 200 kHz.
sampling
and permitted
1 is a block diagram
filter
radari
to be centered
type CMi 07).
bandwidth,
voice
and since the difficulty
ionospheric
for (+) computer
In order
and (3) the recorder.
Hill
in frequency
made available
bandwidth tape recorder
cycles)
this reason
this change here also.
are converted
outputs were
analyzer,
For
SYStem
employed
in which tbe signals
separate
the spectra.
In addition
(2) sync
signals,
(4)
As the recorder
each recorded
on two
in the event of a poor recording.
~
E-MHz
(F
AMPLIFIER
2 MHz
.,
?
~
“c””’
&---Bzl
\
i
1
Q
RECTIFIER
,0
COMPUTER
SAMPLING
Iwwv
START? STOP
VOICE
ANNOUNCEMENTS
Fig. 1. Block diagram of receiver output arrangements for UHF Thomson scatter radar recording system.
IF signals were recorded on magnet;c tape for later spectral analysis (carried out with switch in position A).
3
-.
-—-a.,,,
The tape recorder
commenced
ber of minutes
each
[usually
run and were
feature
was started
on a minute mark),
tbe recorder
7),
used on pla,yba.k
could be activated
easy to play over
nals from
different
lyzer.
generator
a given
This timing
not utilizecl
in our work because,
in the recorder
local
oscillator
frequc
(1.0) frequency
the IF signals.
the spectrum
signal
Thus,
analyzer
Two difficulties
the *00-kHz
LO,
tone
MINCOM
CM !07
TAPE
Instead,
from
reference
encountered
this problem,
a narrow-band
pulses
the 10O-kHz
centered
at 2 Mlfz
signal
seriously)
A second
was obtained
2- P[Hz lF
frequencies.
7’
and then
was encountered
2-MHz
REJECT
CRYSTAL FILTER
0
1.8-MHz
MONITOR
[
,. a- M Hz
&M PL(FIER
1
,00-kHr
AMPLIFIER
ii
2-..=
LoCAL
OSCILLATOR
X2
, ,;oE0~:6E
Fig. 2. Block diagram of system employed to recover IF signals from magnetic-tape
recordings
that eliminated
undesirable frequency fluctuations introduced by changes in tape speed.
4
_——,,
_,.” __
... .__
—m.
-.s,-
of
that of the 1.8-MHz
1“
1
to
was that ‘)dropout’;
amplitude-limited,
problem
whose
was then applied
RECORDER
HARD
L, M,TER
a
in sign to those in
!00 kHz
JxK
was
the short-period
spuriom
as well as (less
was severely
This feature
The recovered
which rejected
The first
signal
tone.
in tape speed introduced
A in Fig. 2.
100- kllz tuned amplifier.
a
ana-
tone to synthesize
but opposite
of Fig. 2.
with the scheme
100-kHz
sufficiently
This Z-MHZ
‘100-kHz wide filter
used to control
tone.
reference
Changes
equal in magnitude
the switch to position
by a 7-pole,
it
of the sig-
by the spectrum
the recorded
it did not reduce
in tape speed.
the spectra
that could bold the tape speed con-
a 17-kHz
the two, a new [l? signal
This “search”
thus making
the tapes were
we used the 400-klIz
that were
caused the loss of timing
TO minimize
used to drive
were
by monitoring
of fluctuations
by throwing
was band-limited
governor
num-
thus separated
Of a run.
being examined
pulses derived
a prescribed
of the tape,
to analyze
from
at 1.8 MITT. as shown in I’ig. 2.
by mixing
was independent
in order
recovered
for our purposes,
speed.
?Y ci,at>+?s in this LO signal
frequency
times
a servo-controlled
stant for the full length of a recording
fluctuations
After
tone marks
directions
of the timebase
counted i O-vsec
included
The 60-Hz
and reverse
run several
the portion
generator
of a run (which always
this interval.
to halt the tape at the beginning
Tbe sync pulses
altitudes.
that governed
The tape recorcler
to the beginning
was Stoppecl.
for botb forward
relatively
timing
about 20 sec prior
and a 60-HZ tone marked
in a manner
in
obtaining
adequate
are
present
put.
This
1.8 -MHz
filter
spectral
at the input to the signal
will
signal
produce
of the +.8-MHz
balanced
C.
solved
the problem,
systematic
mixers
deteriorated
at the
obviated
Analyzer
System
The spectrum
analyzer
employed
integrators
center
grators
spectrum.
in 1964i
arranged
switches
summed
Si to S24 were
and stored
consisted
the voltages
(typically
to be stored
6 minutes),
ages at the integrator
at the out-
filtering
to aging of the 1.8-MHz
erroneous
to cover
outputs of these filters
the IF signals
were
The resulting
results
crystal
purity
for the echo
replaced
The filters
either
in ‘1968 with
were
crystal
were
filters
500 Hz in bandwidth
the upper o r lower
connected
This
sideband
to one of two inte-
outputs were
to the filters
voltages
(together
integrators
were
automatically
equal
pulse
with noise ) at the filter
to the filters
At the end of the integration
to stop tbe integration
measured
The switches
to the gated amPlifier
of noise to be applied
integrators.
removed
for a period
the tm.nsmitted
$ through 47,
pulse of equal length applied
caused a sample
in the even-numbered
the gate pulses
applied
at a delay following
signal
in the odd-numbered
oE@-
and recorded
process,
on punched-paper
j.,,,
f,
FILTER
!
‘*W
‘“r=
,EC,,
F,ER
I
d-= I
%
a&rED
DRIVER
AMP~kER
..
L~
GATE
PuLSES
..
..
I
I
1
Block diagram of spectrum
analyzer
employed
5
—
.,—.
from January
3
/,,,!
at a
and
period
and the volt-
INTEGRATOR
Fig. 3.
of the
the spectral
of a hank of 24 single-pole
as shown in Fig, 3.
then thrown and a second
point near the end of the sweep.
appear
Adequate
shown in Fig. 2 were
pulse (O. 5 m- 1,0 msec)
the height of interest.
outputs were
at Z MHz will
S1 to S24.
On each sweep of the timebaee,
to the length of the transmitted
that defined
200 kHz or 2 MHz
this difficulty.
The rectified
via high-speed
If either
spectrum.
* 966, introducing
mixers
and spanned an 1i -kHz window that could be moved
of the signal
of the
but owing either
during
The single
Spectrum
and 48 DC (Miller)
LO signal.
shift in the mean speed of the tape recorder,
frequency.
that Iargely
i. 8 -MHz
(Fig. 2), a CW signal
level
LO signal
at the center
mixer
a spurious
initially
or to a gradual
power
purity for the derived
1
1963 through June 1965.
tape.
The punched-paper
measured
voltages
(7
P
-.s=
Pn
where
eliminated
sPectrum
by recording
averaged
employed
the system
of the spectrum,
made early
frequencies.
origin,
the search
to be measured
simultaneously.
we did not consider
it desirable
to be examined
because,
the predominant
tbe available
scheme
source
48 integrators
we developed
In the modified
rectifiers
The
the second
above,
since
the lower
half
the two halves.
abou< their
that the effect
and average
the
tapes of the IF signals,
that would permit
across
the full 22-kHz
instrumental
between
tbe filter
polarity.
transformer
(Fig. 3) were
differences
scheme
analyzer
only the difference
analyzer,
to drive
replaced
polarized
outputs were
These
to employ
the signal
effects
48 filters
both
windOw
remained
and use
and the nOise
rectifiers.
from
relays
The
In this manner,
these rectifiers
were
(noise ) pulse was applied
we performed
to the filters
treated
applied
shown in Fig. 4 is not immune from
these,
by a pair of full-wave
were
made nearlY
the noise voltage
errors
as DC drifts,
introduced
separate
on each sweep.
6
produced
to the filters
identical
The original
(S1 tO S48) that switched
the signal- plus -noise
with two noise pulses
and, to remove
rectified
rectifiers
both sets of diode rectifiers.
by mercury
subtracted
between
was now performed
gain differences,
and, believing
wo decided
of opposite
these oppositely
Systematic
between
of the filters
the magnetic
the Z4 filters
outlined
in the receiver),
of the spectrum
Accordingly,
voltages
ond pulse was automatically
urement
to analyze
by the synchronous~y
to examine
difference
to the spectrum
spectrum
the same
speed switches
amplifier
Tests
both halves
the precautions
to store
to obtain a set of
for this is shown in Fig. 4.
providing
by employing
between
despite
as first
frequency.
of the response
to distribute
of inaccuracy.
integra-
only the upper half of the signal
this was not certain
required
for a modification
spectrum.
and this was done by
using the computer
a systematic
we began to measure
This change doubled the time
and prompted
(emplOyed
by the asymmetry
howeve~,
runs
and
a running
signal
each
for a time equal to the normal
here to examine
about the radar
At the time,
was of instrumental
These
measurements.
in 1965, disclosed
this was caused
determined
to correct
we thought it would be removed
amplifier
to be folded
in the gains Of the
necessary.
in the integrators
measurements
described
present,
This pro-
only noise would be present,
‘rbe computer
to drift
to all the other
were
runs were
in order
for DC drifts
the integrators
beam parametric
this caLwed the signals
We now believe
the
in the gains of the even and odd
so that calibration
all such drift
to be applied
or differences
pulse out to a delay where
to correct
If an asymmetry
p~lmped electron-
halves
not removed,
and allowing
We later
corrections
squared
as
in the shape of the measured
differences
in both sets of integrators.
the signals
results.
systematic
of a number of such measurements
We normally
center
However,
of the receiver,
noise voltages
thought it necessary
spwctmun.
response
introduced
the first
We also
tion time.
which
pulse and ~n that due to the second.
errors
out by moving
average
voltage
systematic
bandpass
weighted
removing
computer
at each frequency
[1)
due to tbe first
the undesirable
in each pair were
carried
ratio
S+IJ7”
,
combinations.
integrators
using a digital
(vn)z
bY the overall
filter/rectifier
analyzed
the signal-, to-noise
~~+n is the mean voltage
cedure
were
tape was later
and obtained
due to the sec-
by the first
i.e.,
high-
each integrator
pulse.
the drift meas-
per sweep.
by channel-to-channel
calibration
Again,
runs in which only
,a running weighted
w
\
I
.
.
.
.
.
.
M
m
fig. 4.
average
of these
ment,
calibration
Instrumental
because
from
observations,
system
noise
and no further
subtraction
probably
eliminated
changes
from July
by the computer
were
to the modified
major
employed
to correct
lower
analyzer
1968.
each signal
measure-
than those of the original
the need fOr twO identical
spectrum
were
1965 through June
system
integrators.
was made prior
The
to tbe July i965
made until July 1968 when an entireIy
new
into operation.
disadvantage
is the difficulty
of the modified
of deciding
Where
system,
tbe relationship
quired
power
spectrum.
signal
voltage
~~ will be much larger
P
#
analyzer
in this scheme
the original
was brought
A major
of spectrum
runs was obtained
errors
the. automatic
changeover
made,
Mock diogr.m
not recognized
between
the signal-to-noise
ratio
than the noise
at the time the change was
the measured
is strong
[ (P#
voltages
and the re-
Pn) >> *1, the measured
so that
[2)
= (T#
n
On the other hand, when the signal-to-noise
ratio
is small
[ (P~/Pn)
<< 1]
(3)
implying
that for small
the transition
results
between
are discussed
signals
the rectifier
these two regimes.
in Sec. IV-C.
behaves
as a square-law
The consequences
device.
of this behavior
Figure
5 shows
on processing
the
L,NELQ
RECTIFIER
RECTIFIER
-3
Fig. 5. 5q.are
signal-to-noise
III.
,.-,
,.-,
UNITS
(~,, n- ~n]’ ARBITRARY
,,
m?
of voltage (obscksa) measured by spectrum analyzer shown in Fig. 4 .s input
ratio. For weak signals, stored voltage wasdire. tly proportional to signal power.
OBSERVATIONS
During
calendar
i ‘?63, observations
month.4
A complete
in 19642 and, as a result,
recording
density
the IF signals
profile
our desire
the time resolution,
erally
reduced
to include
near the middle
urements
made,
tbe absence
of major
activity
over
a single
the Priority
and permitting
48-hour
or Quarterly
Table
periods,
Indeed,
This was reduced
The impetus
through dawn and dusk.
period
magnetic
the average
to I hour
U.
temperature
and
in each month.
International
in
We gen-
Geophysical
World
the days on which meas-
index Kp during these periods.
to he averaged
to obtain the mean monthly
of the data it was evident
of magnetic
disturbances
that only
on the results
TABLE II
PROGRAM
was
of this increase
in Sec. VII.
OBSERVING
By
Kp index was less than 20, indicating
an examination
The effects
per,
for these c~anges
As a result
111summarizes
the results
from
in the case of June was this not permissible.
are discussed
90 minutes.
four times
made per month as shown in Table
and the mean of the planetary
with some confidence.
approximately
tbe time to obtain a complete
of each month.
For the msjorit y of the observing
behavior
required
periods
in 1965 to 30 minutes.
we chose to observe
chose these periods
30-hour
were
processing,
the behavior
Days occurring
were
cycle
observations
for later
follow
made for
observing
fewer
was further
to better
were
AS A FUNCTION
OF YEAR
Year
Length of Each
Observing Period
(hours)
No. of Observing
Periods per Mcmth
Time Token to
Measure One Profile
(hours)
No. of Profiles
Obt.ai ned per Month
1963
30
4
1.5
80
1964
30
2
1.0
60
1965
48
1
0.5
?6
8
--
. ...
.
TABLE ill
INCOHERENT
SCATTER OBSERVATIONS
– 1965
Mean K
End (EST)
Begin (EST)
—
12 January
D
16 February
14 January
1000
18 February
2+
Somewhat disturbed
q
0700
l–
Quiet
1300
8 April
Q
1100
1+
Quiet
13 April
0900
15 April
‘3
0900
1
Quiet
18 May
0800
20 May
0200
l–
Quiet
1100
16 June
2100
5+
20 July
0800
22 July
08Q0
10
Quiet
17 August
08$J0
19 A“gwt
D
0800
3-
Somewhat disturbed
1100
16 September
D
1100
3
Somewhat disturbed
0800
28 October
D
0800
2-
0800
I
D
14 September
Q
26 October
D
16 November
Q
0900
18 November
21 December
>.,
Q
1300
23 December
DATA
A.
Critic81
N
scatter
results
max =
of the critical
frequency
made at Fort
Belvoir,
i.24x
As a first
step,
curves
different
behavior
electron
density
i04(foF2)2
observed
values
only the shape
are established
by assign-
(4)
cm an ionosonde.
good records
Previous
Hill C-4 ionosonde
77” W) have indicated
we chose to employ
were
the Fort
not always
Belvoir
obtained
values
August],
since no obvious
the
at Millstone;
of foF2.
differences
very
weli,
On a number of days
but we did not z-egard the
could be found in the shape of the
In the case of June [Fig. 6(f)],
on tbe i5th and i6th that we made no attempt
9
between
of local time for all the hours of observation,
foF2 did not repeat
or the temperatures.
examinations
with measurements
good correspondence
drawn through the points as shown in Figs, 6(a-1),
as serious,
profiles
density
to derive
electt’ons/cm3
we plotted foF2 as a function
were
are employed
The absolute
using the Millstone
[38° N,
malfunctions,
Nmax,
at Millstone
frequency
measured
20-21 .Tuly and f7-48
so different
Quiet
0
——
of
critical
Virginia
Owing to equipment
in computing
obtained
height profile.
foF2 is the F-layer
(e. g.,
Quiet
0
Frequency
ing a value to the peak density
and smooth
0
REDUCTION
F-Region
hence,
Very disturbed
1
—
of the elect ron-density-vs-
where
0
I200
q
—
The incoherent
two.
0700
6 April
15 J“..
IV.
1100
P
to construct
the behavior
an average
24-hour
was
curve.
.IAN
)2
)’365
.
,3
0
,,,
h
,,
.,0 -14~
o
:
$
..
3
...
. . 4.0 —
..0
.
d“
;:...”.
so
z
!,65
.
00
.
.
‘a
m.
,
cc
..
1
I
I
\
I
1
I
I
I
A’
.0
,.ZO
.48,,
EST
EST
(b)
(a)
8.0
TEEIII
x
I
0
I
,
I
..,2
,
t.,.
(
EST
(c)
Fig. 6(a-1).
F-region
.ritical
freq.encyvs
local
time forperiods
ofobservafionin
1965,
.
. . ..(
%noao
.I
,“.
60
$
~.
.. 4.0
I
I
I
(
1
I
I
,
I
\
1
I
.
,6
!,
0
A
.
. .
““
!965
.
2,
0
. .
..
.
o@
I
,
Iz
16202’
EST
(f)
(e)
20
. . . .
“
0%30
EST
JUL
~.
co”
co
I
(
!
.
. .
. .
00
.
. . .
. .
04e
162024
O+SIZ
15
1
..
,,65
. .
. .
6.0 -22A
.
~.
.
A
:
..
. . 4.0
2
I
I
AA
z..
20
t
[
(
0.,,.
,620*’
o.a,,
t
,
,6Z0’
EST
EST
(h)
(9)
Fig. 6(cJ-1). Continued.
14
,
I
I
I
,
[“”
,,,
.
.,0
Ooco
TImiEL
SW
1965
,4
.
,s
o
A
A
cm
““ . . ...
“’ OOwm
co
~..
m
0
0
$
..
.
Go
-.
4.0 %
o
A
2.
.
27
-i2mcL
=
~
o
Cmm
26
m
Mu
M
“...
. . . . .
00
0
~
0
I
(
.8,,
(
,
,
I
t
!
I
3620”
,s1
EST
(i)
(i)
,.0
t
I
..a~,
,6’”’
EST
(1)
Fig. 6(o-1).
Continued.
Electron
B.
DenSiky PrOfile
Echo power
yield
vs delay observations
an echo power
profile
I
0,5-,
using O.i -,
P~ vs height
and 1. O-msec
pulses
were
combined
to
h from
T,&
I
Ps(h)
(5)
=
h’
where
T ~ is the equivalent
echo temperature
Next,
these
were
power
profiles
to-ion-temperature
observed
corrected
rat io T~/T i obtained
at the completion
for the effect
from
on the scattered
the analysis
of the signal
of the sweep integration.%
power of the electronspectra2
i + (T~/Ti)h
N(h) = ps
These
obtained
corrected
Although
To do this,
profiles
results
aII the power
density
the value of the peak electron
electron
profiles
June,
the accuracy
(Secn,IV-D).
Electron
probably
density Nmax
decreased
i 20-km altitude,
i.e.,
The ratio T~/Ti
to July,
These
curves
(between
above,
temperatures
temperature
were
charts were
of Nmax.
in the values
of
to yield
frequency
the width
for fixed
on the assumption
everywhere
is f OMHz.
and the values
that
This
obtained
T:.
and plotted
in the CIRA
profiles
from
of these quantities
prepared’
used
and smooth
next hand- scaled
being underestimated,
assumed
corrected
on charts,
then determined
by the symbol
these plots was employed
These
values
the same procedures
were
frequency
into hourly groups
to true values
The peak
the power at the center
showing the variation
and are represented
from
introduced
machine-plotted
smooth
and ratio
These
the fixed temperature
scaled
and its shape was
(Sec. C below).
we employed
were
and that the plasma
divided
with re-
This mean pro-
For the data taken since
errors
next drawn through the points and extrapolated
as outlined
electron
(Ref. i ).
of Ti and T~ were
were
altitudes
shape.
averages.
to July)
and ion temperatures
leads to the electron
as fictitious
The values
sity profiles
(Prior
using charts
ion present
of T~/Ti
the scatter
only the hourly
at given
previously,z
owing to systematic
made prior
The electron
by interpolation
of Ti and the ratio T~/Ti
Smooth curves
scaled
30 minutes,
was taken to be the mean of the individual
(to half peak power)
0+ is the predominant
are described
every
to compute
with the average
mean values
the 24 points in each spectrum
and that in the wing).
last assumption
obliged
has been discussed
the measurements
of w~
values
was obtained
in each hour were
drawn through these by eye.
the parameters
and ratio
profiles
and Ion Temperatures
in,1 964.2 That is,
were
obtained
of this procedure
T:/Ti
In analyzing
profile
that we were
to Eq. (6) using the hourly
for the se mean hourly
C.
density
was so large
in height to place the peak at the mean of the peak heights,
according
The accuracy
titious
then assigned
and a mean taken to obtain a profile
was adjusted
corrected
values
were
an independent
spect to the peak,
curves
(6)
m ax 1
via Eq. (4).
of the temperature
file
[
i + (T~/Ti)h
as a function of altitude.
down to a value of 355-K at
i 965 model
atmospheres.
in Eq. (6) to obtain the corrected
were
then employed
to convert
den-
the fic-
viaz
(7)
lm3m
NO
YE* T“(RO
FIT
,E~
TRIAL?
PARABOL.
P = bo+ b,f
eb,+’
COMPUTE
YES
cOMPUTE
~
ccTRY
8
}
G-J:,HIH’D
!S PEAK
WITHIN I“Hz
m,
c
NO
HAVE 2
POINTS
YE,
0’CENTERYES“EN‘EM0vED7
OFMbTRIX?
c~G:TE
OUT
OF PEN
w
R
NO
>
ANY
4X
MEAN
t’
Fig. 7. L.gi c fl
This section
was
w
diagram
employed
of part of computer
to
fit
parabola
to
wing
program empl eyed to
of
spectrum
in
way
process
signal
spectra
that would eliminate
to
obtain
temperature
spurious points.
measurements.
This
expression
higher
values
is believed
probably
only at altitudes
D.
Spectra
first
T;
These
(10 or more
Ti and T:/Ti.
to at least
graphical
method:
spurious
points.
,,,
expressions
i.e.,
deviations,
points.
to the remaining
substantially
for drifts
and channel-to-
In the $ourse
in time taken toubtain
of developing
the nonlinear
and the echo Wwer
the spectra
hence,
“oltage
always
as the square
tion would be correct,
of the signal-to-noise
be zchieved
nately,
log,
be greater
and a proper
ratio
would be to adopt some
this could not readily
coded on the punched-paper
tape,
be done.
The effect
T~/Ti
of interpreting
to be overestimated,
the two effects
these assumptions
in em-or.
and, again,
result~
pulses,
and after
signals
in error.
will be chiefly
before
relation
he interassump-
some
knowledge
altitudes.
Unfortu-
tape but in a separate
1.0 msec)
was en-
the O.5-msec
measure-
or
pulses.
Eq. (2) will be to cause
will be least
interpreted
Therefore,
in T& since
“sing
Eq. (3), Ti
the effects
to cause parts of the Ti curve
July,
Con-
the best that could
with 1, O-msec
The error
[Eq. (3)].
neither
would require
Eq. (2) to interpret
altitudes
analyzer
tbm noise,
voltages
altitudes,
law at these middle
Fur strong
we rec-
the signal-to-noise
on the punched-paper
using the incorrect
results
obtained
of the echo power
As tbe length of the pulse (O. 5
one another.
provided
we knew that
weaker
that the measured
T& should not be greatly
on the temperature
By comparing
power
made at greater
weak signals
and an entirely
analyzer,
invariably
of the spectrum
and Ti to be underestimated.
tend to compensate
will be overestimated
were
At intermediate
we chose to employ
ments and Eq, (3) for the measurements
as cmtl<iied. in
this program
Since this was not available,
intermediate
sdopted
tbe temperatures,
with the earlier
requiring
was not recorded
was then
by the new spectrum
using 0, 5-msec
interpretation
a paraboM ~~~
than a cer-
The computer.. program
in complexity,
measured
pulses)
[Eq. (2)].
at each frequency.
the height of the spectrum
hence,
than unity,
root of tbe echo power
by more
the edges of the .Spectrum,
the delay,
to determine
voltage
(225 km),
ways. .@f rejecting
values.
upon experience
examined
using the earlier
gain differences
grew
of
in this way was
The parabola
,.,alue.
could be taken as the best estimate
altitude
values
Zm.m the final procedure.
Despite
program
(using 1-msec
deviated
rejected,
chanw:l
968.
the signal
Based
at high altitudes
at the lowest
would nearly
preted
the computer
between
(Sec. H-C),
the measured
versely,
ratio
relation
obtained
to temperature
To locate
the program
temperature
polynomial
or in the wing of the spectrum,
the half-peak
until mid-i
expressions
fo? various
was in devising
7 shows i“ schematic
was net obtained
ognized
reduction
the computer
high-order
than could he achieved
and all. such points were
Figure
of all these .requirements,
savings
important
The philosophy
Thus,
these into analytic
obkained by fitting
better
with machine
See; :li:: As a result
ersion
by the computer.
and width parameters
satisfa~toryv
immense
were
to three ..poirhs nearest
to correct
but at
gathered.
hand analysis,
the heig!it of one of the wings in the spscirum;
line was fitted
was also required
this is probably
were
test was then made to see if zmy points
tain number of standard
x t O-i “K cm3,
of ratio and width computed
Thus, to find the height in the center
refitted
a straight
analyzed
and inserted
to the values
encountered
to the points.:A
to determine
,.
In practice,
completely
and ~,
of the ratio
i percent,
The rna,jor. d.iffimdty
was fitted
analytic
The conversion
accurate
were
of l~h
terms]
(T&/N) <2
few useful measurements
t~’e same as in the earlier
the parameters
and Ti.
expressions
provided
(July and Later)
in July and later
for this was basically
estimated
to yield
and Ion Temperatures
obtained
accurate
Te to be overestimated.
above about 700 km where
Electron
employed
to be reasonably
causes
it appears
that the error
is
of
to he
largest
in the region
300 to 500 km where
sate for this when constructing
used to correct
the electron
as the data taken prior
The accuracy
The largest
the spectrum
numbers
less
V.
of measurements.
were
RESULTS
A.
Diurnal
over
mean profiles
were
was the random
associated
range
the systematic
300 to 500 km; hence,
reported
herein.
used to correct
we place
Unfortunately,
the electron
with
by averaging
taken in July and later,
in the altitude
curves
error
has been
these
density
profiles.
DENSITY
Plots
electron
the height interval
density
profiles
obtained
intbe
of constant electron
manner
density
i50 to 650km and O to 24 hours EST.
month of June [Fig. 8(f)]
where,
to plot the 48-hour
owing to the markedly
period
loss of much of the last Iz-hours’
constructed
to compen-
in the same manner
and this could be reduced
than on any others
in Figs. 8(a-1) as contours
necessary
These
corrected
to July to obtain temperatures
For the measurements
the random errors
ELECTRON
The mean hourly
presented
prior
in the measurements
pm sent also in the T&/Ti
FOR
curves.
themselves
width and shape parameters,
on these measurements
uncertainties
temperature
and were
employed
uncertainty
(in Ti) exceeded
reliance
profiles
We attempted
to July.
discussed.2
large
the mean hourly
density
of the procedures
determining
errors
Ti has been underestimated,
temperature
in full.
profiles
averaged
over
behavior
equipment
data during this period,
in See, IV are
plasma
frequency)
The only except ion to this is the
different
Unfortunately,
outlined
(actually,
from
day-to-day,
malfunctions
it was
caused the
To obtain this plot [Fig. 8(f)],
intervals
of 2 hours in order
to reduce
we
the uncer-
tainty in the measurements.
i
B.
Me8n Daytime
For
some
purposes,
use than tbe complete
density
curves
Figs. 9(a-k)
and Nighttime
the electron
time
There
.
.
density
provided
1000to
These
in which the latter
is a noticeable
increase
discussed
earlier
smaller
C.
and less
some period
were
intbe
themselves
curvature
The effect
constructed
computed,
average
are presented
from
i.e.,
in
the hourly
aver-
by averaging
the
of hmax and Nmax.
for the region
We believe
through Eq. (6),
were
are of greater
we computed
above bmax intbe
this tO be caused by the errOrs
cause the density
is not present
at night,
daytime
tithe
ratiO
to be progressively
overesti-
since then T~/Ti
tends to be
Discussion
A single
of the winter
daytime
tween i200 and 1300 hours.
at sunset which is probably
summer.
over
Accordingly,
altitude-dependent
The main features
of 1964.
which,
altitude.
averaged
averages
these the mea.n values
for July onward [Figs .9( f-k)].
mated with increasing
profiles
by Figs. 8(a-1).
i500 and 2400 to 0300 EST and these
respectively.
shapes and assigning
profiles
T:/T,
history
for the periods
andi O(a-k),
ages in the same manner
profile
N(h) Profiles
maximum
Above
enon to the rapid decrease
rise.5
however,
counterpart
observed
in Te occurring
This suggestion
.
in <965 differ
density
there
of a second
.—
from
those
usually
be-
peak occurring
evening increase observed in
40
we attribute this phenom-
eclipse,
at sunset and the redistribution
has produced
little
is found to occur
is evidence
of the marked
during a solar
46
—-
observed
in the peak electron
hmax,
the winter
Based upon the behavior
which this gives
diurnal behavior
a spirited
discussion
of the ionisation
to
in the literature
that
,,,
,LA,MA
,,66
FREQuENCY (MHz)
0,
,00 -
600 —
%
,
:
,Ca
.
:
.
?00
,0 0
048!2
,6~M
,*T
(a)
*LAW.
FREQuENCY (MHZ)
.,
,00 -
z.
:
.00
:
,Co
?co
I
I
046!,
,.20*”
EST
(.)
(b)
Fig. 8(o-1). Contour ofconstant
formeos.rements
made in 1965.
plosmafrquency
observed
as functions
of height and local time
17
, .,..,m,,%,
I
I.48,.
\62024
EST
E,,
(.)
(d)
...
,,
!5-,7
WM ,969
PLASMA FREQuX.CYIMHZI
K
EST
(f)
Fig. 8(cI-1).
Continued
48
ml
,.0
w
Jk
600 —
,.0
*.*
,.5
,$
,,.
s..
,,0
!5
\
3.5
g
:
,00
ii
.
4.0
4.5
,.0
300
t..”
.
5.5
.--=.
3.0
~
J--
I,
\
,Cc
/
_/’
\
@
WAS..
I
0.81z
<
/
I
IS
J“L !,.5
F. EQUENCY (MHZ)
I
1
202
,s1
,s7
(h)
(9)
I
.484.
f.,.,,
,,1
(i)
(i)
Fig. 8(a-1).
Continued.
<9
(k)
I
I
oaf,
,,2024
EST
‘oom
,.0
,0,
([)
,0.
E,T
Fig. 8(wl).
Continued.
20
.00
TEEi3
14EAN MYT4ME PROFILE
(4000-$500
UT)
JANUARY ,965
600
I
5
> 400
%
r
\
Fired,. 4.6 x 405 ELECTRW/Cm3
,0,
(0)
lmm
I
MEAN DAYTIME ,Immt
(1000-1,00
EST)
8-0 APR)L 1965
\
t
“,1
2
s
7,.2.50
RELATIVE
1
DENSITY
mr
[PMCM
(c)
(b)
Fig, 9(a-k).
Mean daytime de:si~
profiles; these plots obtained by averaging all measurements
between 1000 and 1500 EST. Nmox is mean peek density during this time period.
Zi
“t
—
\
200
I
Fimo,
3,35 x
d cLEcmo
Ns/m3
.,..
‘(
o
/
1
\
I
1
1 1 1111
,71.=5.
{,
I
1 I
I
II!
ref.,
[wc,”ll
RCLAT,VE DENsITY
(9)
loco
~
OAYT!ME
PROFILE
[(000-1500
EST)
,E,TwBER
1965
6m.z : ,3
h.,”
. 3,2 x ++,.,,.,0.s/.”’3
/
1
,
1
1
.,!..,
! 1 1 I II
,,,.
(”,
1
205.
1
1
I
. @
Ewmowc.’
,00
/“
t
1
7.
L
“1
1
z
1
1
,,,.,,
C’GISIT” (Percent]
1
II
1 I
7,02.50
”,
,,.,1,,
(i)
(h)
Fig. 9(a-k).
Continued.
23
1
,,.,!,.!,
1
1 1
11
701c
\
(i)
L
i.,,
5.2
x ,05 m,cmo.v+
/
I
,..-.
,2
(k)
L
t
Fig. 9(a-k).
Continued.
24
\
800
~
.s.,
NIGHTTIME PROFILE
(2$00-0500
EST)
,* N”An” ,,65
\
(a)
MEAM NIGHTTIME PROFILE
,2!00 -0300
EST)
.-e
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\
“f
,
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II
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, L
I
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I
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= 1.! x
DE I+S!TY
{9,,.”11
I
I I Ill
,,m-~
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@CL
ECTRONS/Cm3
\
(.)
(b)
Mean
nighttime@wity
Fig. 10(a-k),
betwee. 2100 a.d0300
EST. N
i.,”
profiles;
Inox
these
plots
obtained
by
averaging
is mean peak density during this time period.
25
all
measurements
I
I
Ill
TO,,
.
.,,,
ii..,
.
\
200
NIGHTTIME PROFILE
(?lO. -0300
,s, !
,,-!5
iPRIL 1965
1
,,2 x
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KTRrJNs/cm3
;
t
1
1
o
I
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.,,,7
1 I \ II
,
!0
)., DEmsll”
I
m
1 I 1 (1
m
70 +.,
IWm.tl
(d)
!00
-
ME,,
N,OH, T>ME PROFILE
(2100 -0s00
ml)
, ,“LY (,s5
.0.
~
. .0 0
~
‘1
“!
‘$
-
fima, . ,.6 x ,Os ELW,0N5/Cm3
\
Fmo,
/
t
1
a
1
I
I
,7!
1 I II
.,,.,,,,
1
020
1
1
1 1
m
I L
!.
O, NSIT” (Owe”!)
(e)
26
,.36
x,05C,ECTRONS/mB
0-”
.00
:
~ ...
:
Y
.,.,
l\
N,G”,TIME PROFILE
,,,00 -0300
EST)
MJGU,T ,965
Nm.x= ,,7xm~mcTRoN5/m3
I
/
1
1
o
{z
t
! I 1 Ill
,74.
ms.
RELUT, VE DENS(TY [PWWI1
1
I
1
I
I
Ill
m4,
(9)
\
I
I 1 1
,7
)11
!
I
\
!...,,
RELATIVE Oc.sl.Y
1 I 1
~.
W,,”,,
(i)
(h)
Fig.
10(.a-k).
Continued.
27
.mr
.,,.
H,G”TT,ME PROFILE
121.0-0300
EST)
,OVEMBER 1,65
(i)
\
C,”ot
. ,,6 xm. CL
EC,.OWG.,
/’”
“,
I
*
I
I
I
57,.
R, L.TIVE
1 Ill
C.c.ml”
1
20s0
1
I
1
I IL
m!.
.,.,
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{,erGe.t)
.“.
1
Lt!&!EJ
NIWTTIME
PROFILE
(2!,0 -0300 Em>
C’ECEMOER 1965
~
;’””
(k)
ire.,. ‘,5.!0$ ELECTROWCF
/-”
m.
}
Fig,
Io(a-k).
Continued.
28
is too extensive
attempt
to review
here,
However,
to model the phenomenon
ity equation
we may
using a time-dependent
has been performed
by Thomas
electron
and ion temperatures
based
produce
the evening
but a later
increase,
the
Millstone
model
points as follows.
An
solution to the electron density continu12
employing
a simple
model for the
and Venables
upon
the salient
summarize
observations.
model
This
in which the electron
failed
temperature
to re-
was allowed
to govern
the loss rate according to the laboratory
results of Schmeltekopf,
et al., ‘13 did produce
-—
i4
maximum.
i5
Kohl and King,
and Kohl, ~ al.,~6 have argued that neutral winds, which serve to drive
an evening
ionization
sities,
down the field
lines
during the daytime
are set up in the upper atmosphere.
the wind direction,
recombination
which causes
rate.
The evening
variation
depress
maximum
Strobeli7
treatment of the problem seems
18
$t_Q.,
who solved the time-dependent
and Sterling,
of winds,
the original
and the variation
explanation
of ionization.
height of the layer
s ity.6
peak to be raised
This feature
8(1 ),
seems
during winter
from
the c~njugate
scatter
of the plasma
19,
by the F-region.
ionization
of Millstone,
for the F-region
thought to reach
density
understood,
During
summer,
winter
to summer
behavior
Figs. 8(c) and 8(d).
March,
and summer
Reasons
day electron
(i)
density
lines
mnlit
drifts).
throughout
in den-
excite
is tbe source
complicated
at sunset.
quite rapidly
of signals
c?n act as a sOurce Of
the downward
sunset,
of the ionization
temporal
flux is
and thereafter
decrease
seen in these
morning
hours is not
and spatial
variation
of
peak usually
reaches
Tbe transition
from
a maximum
before
the characteristic
around equinox as may be seen by comparing
behavior
is encountered
from
mid-October
through
through September.
maximum
have been discussed
composition
blow away from
of higher
by means of incoherent
in the early
is thought to be caused by either
hemisphere
Hill
in winter.
at the layer
mid-April
that
(Direct
at Millstone
in the spectra
At equinox,
about 1 hour after
of ionization
the night.
arriving
that the $fltonOsphere
for their occurrence
winter
diffusion
This was accomplished
much of the night.
density
from
into regions
that
for the
when it was recognized
of photoelectrons
night.
change in the neutral
winds which in the summer
the
a redistribution
it is necessary
of downward
lines that the photoelectrons
evening
in summer
in terms
remains
detection
maximum
occurs
behavior
for the summer
a summer-to-winter
down the field
to Millstone
from
about by the more
At Millstone,
to indicate
is the predawn increase
sunset,6 was discarded
it is believed
the electron
including
appear
for it in these data is found in Figs. 8 (k) and
tube that must occur
noon, and a second much larger
out by
equation
electrodynamics
diurnal behavior
If the protono sphere
of the field
this idea.
in f965 than in + 964, and is thought to disappear
the reason
but may be brought
the temperature
as that observed,
in
of lower
pronounced
throughout
increases,
supports
continuity
den-
a reversal
to have been carried
Both studies
(or possibly
a peak of 1040 electrons/cm2
or less monotonically.
nocturnal
electron
Best evidence
point during the winter
For the latitude
more
conjugate
observations
scattered
by winds
conjugate
of this has been obtained
from
in that the rapid fall in Te initiates
an increase
for this phenomenon,
following
the region
temperature.
of the winter
far less
offered
the pi-otonosphere
evidence
feature
at sunspot maximum.
An explanation
from
com-ect
to obtain as large
A second anomalous
completely
of electron
is partially
However,
results
of hmax seen in Figs. 8(a-1)
The most comprehensive
effects
the midday
to be driven up the field lines to regions
the ionization
The general
and thereby
above.
The depressed
or both the following
of the atmosphere,z
f‘23
mid-
effects:
or (2) nentral
the equator at noon and drive ionization
15
rates.
Experimental
evidence favoring
recombination
29
.
.. .
.—
the first
I
of these
carried
explanations has been obtained in the L-band incoherent scatter observations
41,24
These appear to indicate that, relative to atomic oxygen (0+),
out at Millstone.
mole cular
ions (02+ and NO+) are present
the 10Ss of ionization
largely
proceeds
to greater
altitudes
via the charge
in summer
exchange
than in winter.
Since
reaction
0+ + N2 -NO++O
NO++
this suggests
is lower
N+
e-
O+hu
(8)
that the abundance of the ionizable
in summer
1).ncan”
species
recently
reviewed
all tbe explanations
concluded
that a variation
in the neutral
composition
suggested
that the change in composition
is brought
mer to winter
hernispbere,
If this is the case,
and that a rapid changeover
sphere
causes
Changes
lence,
in the relative
and becomes
neutral
better
collision
frequency
forms
Continuation
are probably
transport
as the sun moves
and
of O from
13e
the sum-
(i) and (2) are related,
into the northern
could also be bmugbt
ceases
to be mixed
its own hydrostatic
for such changes from
at ‘t15 km,
anomally,
hemi-
incoherent
of these
studies,
needed to resolve
equilibrium
scatter
studies
together
the relati”e
about by
due to turbudistribution.
of the ion-
with more
importance
and
of the
effects.
scatter
measurements
seasonal
the seasonal
anonmlly.
ELECTRON
A.
AND
ION
t? the density
and local
results
is found,
it seems
inadequate
to account for
TEMPERATURES
we attempted
of Figs. 8(a-1),
Te and Ti Profiles
to present
i,e.,
our temperature
as isothermal
results
contours
in a manner
drawn a. functions
analogous
of height
This work has not been altogether
very rewarding
since, apart from somewhat
4,6
we tend to find that the temperatures
remain fairly constant
bebavior in winter,
complicated
the daytime
two regimes
urements.
and again during the
is sufficiently
in presenting
to a single
the results
In addition,
true at dawn,
altitude
in order
where
and nighttime
tbe transition
it is properly
it has been necessary
to obtain adequate
time
for i 965, we have plotted only tbe average
(4000 to 4500 EST)
and i2(a-k),
nighttime.
rapid that it is doubtful whether
This is especially
ments restricted
(Zi 00 to 0300 EST).
These
explored
to carry
resolution.8
temperature
are given
between
tbe
in these measout measureAccordingly,
PrOfiles
fOr the
in Figs. Ii(a-k)
respectively.
When drawing
(indicated
peratures
velocity
winds has been provided by 1%-ench inco27
IIowever,
alnear the F-region
peak.
time.
throughout
daytime
drift
neutral
of the wind velocity
and Nighttime
years,
involving
of vertical
variation
28
Mean Daytime
In previous
ments
about by global
then it may be that effects
abundance of O to NZ in the Fi-region
measurements,
seasonal
tbe two types of behavior.
one in which each species
though some
VI.
(02 and N2)
is the only one that will fit all the facts.
wind pattern
between
Support for the second explanation
herent
to molecular
for tbe F-region
(near 110 km) at which the atmosphere
has found evidence
rocket
various
in the global
the abrupt transition
a change in the altitude
WeJdteufe12’
(0) relative
than in winter.
these curves,
by the vertical
are essentially
we have been guided by the height resolution
bars)
as well as the belief
that electron,
the same below about <30 km (Refs.
30
of the measure-
ion, and neutral
14, 29, and 30).
Therefore,
temboth
(a)
Me..
daytime
electronand
ion-temperature
profiles.
These plots obtained by averaging
Fig. 1 I(a-k),
all measurements belween 1000 and 1500 EST. Bars denote height of exploring pulse.
From July onwards,
ion temperature between 300 and 500 km has been underestimated
(see Sec. IV-D).
3i
,
)
0
1
...
1
1
!
sw
1
f200
1
1
1
,6.0
TEMPERA,”,,
1
‘am
1
1
1
‘w
“m
[w)
(c)
!3-$5 Am,,
t
ma
!OOO-! 500
1965
EST
I
1
I
{
o
tllllllll
.0.
800
120.
le..
TEMPERATURE 1°Kl
(d)
Fig,
1I
(a-k).
32
Continued.
z.~
24m
2“00
1
0
I
1
1
4CU
1
1
8..
1
!
1
1
I
t2..
l-o
TEMPFRAT”RC {W
I
=..
1
1
,4W
1
I
(
,4~
I
1
p,,.
1
(.)
,.,
!..,
JULY $965
moo -1500 E3T
I
~
.
so. –
:
.
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..0 -
xc –
,
I
.
.Ca
,
em
1
,
,
,
,
!200
IWa
TEMP6RAT”RE PK1
I
~
(f)
Fig. I l(a-k).
Continued.
33
.,
z...
3-
AUGUST
,000 -t50C
1965
EST
,00 —
:
6“0
‘i
$
Y
i
40. —
200 —
I
\
..0
0
I
1
8.0
)
1
120.
i
I
I
I
.. . .
1
~
t
1
1
‘*”
‘am
I
,4~
z...
TEMPERATURE {-K)
(9)
(
,F,,EM8ER
,,65
moo -,500
,s7
am —
I
:
60”
:
;
.m —
200 —
1
“
,
.0.
1
I
*CO
1
1
1
1*OO
I
!600
1
TEMPERATURE VK]
(h)
Fig. 11(a-k).
Continued.
34
1
moo
1
em
T/
t
J
J%’”
.
“t
t
0
I
400
1
800
I
1
1600
TEMPERATURE
1
\
1
1
I
\
I
I
I
f,.,
mm
‘“w
‘m”
(T1
(i)
‘“””r
‘
-iIEmzl
4 ‘00”-”00
‘“
-
,
1
I
,
m
\
1200
,sOO
K1.!FCRhT”,,
?0
(i)
Fig.
Continued.
11 (a-k).
35
I
‘“m
1
I
400
1
,800
!.00
mzml
%=3’%
t
1
we
1
o
,
I
em
1
I
!.W
I
TEMPERATURE
l~K1
I
,
moo
I
I
I
2.W
,400
2,M
(k)
Fig. 1 I (.-k).
Continued.
!00.
T@!mL
JANUARY
2!00-0300
1965
EST
m. —
/
~
‘OO
k
g
I
:
400 —
.0. —
1
400
1
“
I
1
SW
1
1
!200
1
!
1
I
,600
1
,~
1
z~oo
1
1
1800
TEMPERATURE W
-.1
(a)
Fig.
12(a-k).
cdl meawreme”ts
Mean
nighttime
behveen
2100
electronand
0300
and
E5T.
ion-temperature
Bars
denote
36
profiles.
height
of
These plots obt~ined
exploring
pulse.
by averaging
-
F,,WA,Y
2400-0300
,,.5
EST
. ‘“””E
~
,
/“
/
/
1
a
I
I
1
4,,
1
I
s00
I
1
!?00
I
1
!600
TEMPER AT” RE (°K1
(c)
Fig.
12(a-k).
Continued
37
I
1
*W
{
,4w
1
I
‘mo
—
!3-!5
APRIL
2100-0300
!965
E*T
,00 —
.
:
6C0 —
:
*
‘
+00 —
200 —
)
mm
I
!600
,,0.
I
I
2400
(
1
mm
TEMPERATURE lPK1
(d)
.
f
.00
1
I
ma
1
I
!m.
I
,..
1
!..0
Pm ATui7E (P.)
(e)
Fig.
12(a-k).
Continued
38
I
I
2...
I
I
24..
I
1
.~o
)
.
!
I
800
1
,..
)
I zoo
!
i
I
1600
1
2000
1
1
1
I
’400
I
2’00
TEMPERATURE lPK1
(f)
,06.
~
r---”--”””””’”
AUGUST
2,00-.300
800
~~~
0
I
4..
1965
EST
1
1
80.
I
j...
!
!20C
TEMPERATURE 1.K1
(9)
Fig,
Iz(a-k).
Continued.
39
1
,@o
1
1
2“00
1
“0”
,.00
Tmm
,,,,,.,.,
*,,5
2100-0300
800
EST
[
I
,,00
1
I
!600
T.M,CRAT”R
1
!
2400
I
2000
1
1
2*OO
E [r. )
(h)
OCTOBER
800
o
I
$965
2,00-0300
EST
[
1
1
400
1
1
1
eca
1
I
!200
1
Mm
I
TEMPERATURE PK]
(i)
Fig.
12(a-k).
Continued.
40
1
mm
I
1
24~
I
1
,~.
I
,“””
=
1
40.
.
1
,.0
I
1
1
1600
I
I2..
TEMPERATURE
I
.000
I
1
\
z...
I
2*OO
I
(w}
(i)
DCCEM8ER
,965
2100-0300
EST
[
.0.
t
0
1
1
.OO
1
1
S@
1
,200
1
1
,..0
TEMPERATURE ?K]
(k)
Fig.
12(a-k).
Continued.
1
I
ZOO.
I
1
MO.
1
1
2,.0
~
Te and Ti have been extrapolated
downward
at 420 km in the CIRA
atmospheres.
,
For
the daytime
1965 model
results
obtained
after
to the value of 355-K employed
June [Figs.
ii (f -k)],
the curve
for Ti has been drawn
through the point at 225 km, and then taken higher than the plotted values
underestimate
“cry
in Ti (Sec. IV-D),
However,
it seems
as the temperature
to compensate
doubtful that this portion
for the
of the curve
is
accurate
as the exospheric
temperature
during these months is thought to have been of the
Ii
of 800a K or higher.
As noted earlier,
the electron temperature
should be substantially
order
independent
of the error
Discussion
B.
The temperature
the photoelectrons
energy
escaping
behavior
created
to escape
photoelectrons
ters
in Ty
the local
ionosphere
the conjugate
electrons.
ionosphere.
in the electron
ducted into the ionosphere
that the escaping
of the escape
energy
of these?5’37
included.
theory
some of its energy
on the order
the effects
via Coulomb
temperature
gave rise
behavior
escape
sophistication
However,
This
encoun-
directly
gradients
to
seen
to a heat flux con-
(Ref?,, 7 and 31), and assumed
Recent
thermal
ionosphere.
to be given
theoretical
estimates
32-35
support to this conclusion.
of photoelectron
and the measurements.
daytime
of 5 X i 09 eV/cm2/sec
of the F-region
the enormous
is presumed
that this effect
has been made with the Millstone
Despite
photo ionization
postulated
m upward flux of
to the conjugate
in the protonospbere
of the energy
Some of
have sufficient
during the daytime,
to account for the large
we earlier
flux have given general
comparison
Thus,
previou.sly.4
in the atmosphere
the protonosphere
flux was even larger.
A number of studies
direct
completely.
The balance
In order
temperature,
has been discussed
of ion production
that traverses
flux deposits
with the ambient
at Millstone
in the process
is established
photoelectron
observed
of the magnitude
have been carried
out in which a
35-37
In the mgst recent
measurements.
and fine-structure
of these
models,
these may simply
cooling
of oxygen
were
remain
between
differences
result
from
uncertainties
both
the
in the
cross
sections,
collision cross sections,
and other parameters
that were em35
ployed in the calculations.
For example,
it was found that the results of the two studies differ
35
more widely between themselves
than with the measurements.
One phenomenon
existing
models
ticles.
These
that has recently
is the importance
encounters
they cause a portion
b’dckscatteredi’’
local
serve
come to light and is not adequately
of elastic
to limit
the escape
of the flux of photoelectrons
The albedo
of the atmosphere
many of the photoelectrons
to make several
their
into the F- region
the ene?gy
or penetrating
of the escaping
and suggests
line?’
served
at high altitudes
The photoelectron
served
is still
is deposited
flux,
from
the conjugate
photoelectrons
will deposit
is possibly
traversals
accurately
hemisphere
their
to be
energy
in the
as high as 0.5 (Ref. 41] causing
of the protonoiphere
before
losing
This must cause a larger
at one end.
to appear
in any of the
and neutral par34
In addition,
as pointed out by Nisbet.
in the form
flux can he determined
than was previously
from
of heat conducted
the temperature
all
fraction
of
along the field
gradient
ob-
thought,
escape
sunlit and supplies
directly
the protonosphere
more
included
photoelectrons
flux is believed to be responsible
for the high temperatures
ob4,6,7
during the winter nights
because at this time the region conjugate to
at Millstone
Millstone
photoelectrons
that the escape
between
arriving
38-40 so that not all the arriving
ionosphere.
energy
encounters
in the local
is on the order
heat to the protono sphere.8
ionosphere
by arriving
of half the daytime
42
It is not certain
photoelectrons,
value.7
Observations
how much heat
but heat conducted
of the plasma
from
lines
in the spectrum
conclusively
lines
of the
that
are observed
deposit
During
temperature
the F-region
hydrostatic
pressure
MAGNETIC
during
the winter
nights
shou,
numbers. $9 However,
pksma
energy
the photoelectrons
off”
(convection)
below.
with electron
the daytime
to a
to warm the F-region
temperature
as it
as Te 512 , the lowering
the proton osphere
of
to continue
altitudes
of Millstone,
hut quite important
DISTURBANCE
between
20,42
Ackiitimv+l heat is brought into the P-region
20
under the influence of the reduced
sunset.
to lower
to persist
of the protono sphere.
is heated during
continues
the heat 10Ss, permitting
For the latitude
conduction,
appears
by the cooling
the protonosphere
for many hours after
than thermal
A.
difference
and at nighttime
varies
“chokes
of electrons
I’-region
that whatever
temperature
and Rowhill,42
Since the heat conductivity
via transport
Vfl.
a small
above that of the F-region,
the F- region
effective
the
in significant
high altitudes.
nights,
out hy Geisler
temperature
to warm
from
Millstone
hmax F2, indicating
at rather
the summe~
signals
do reach
and ions and this is thought to be maintained
As pointed
cools.
scatter
only above
is introduced
electrons
Thomson
photoelectrons
this process
20
is thought to be less
nevertheless.
EFFECTS
August and September
The average
magnetic
I<p figures
In August and September,
were followed
a direct
by disturbed
comparison
recomputed
the first
quiet and disturbed
periods.
111are for the entire
observations
‘rhe results
were
months therefore
quiet and disturbed
and nighttime
days,
in Table
These
of consecutive
the daytime
given
24-haursl
temperature
afford
periods.
averages
are presented
period
relatively
of observation
quiet periods
the opportunity
In order
to do this,
fOr these mOnths,
in Figs. i 3(a-b)
tmd
for making
we have
separating
tl?e
and ‘14(a-b) for the two
months.
The August storm
.,
sudden commencement
this, comparison
appears
to have been one of the principal
of Fig, ‘13(a) shows little difference
f 7 and i8 August,
The slightly
lower
may have been caused by the slightly
~t $imuld seem
that the observations
commencement
averaged
for significant
over
the periods
in Fig. 53(b).
increase
There
in electron
The September
electron
higher
electron
conducted
appears
to be a distinct
temperature
storm
ohsemed
densities
to have been too short for
between
increase
as encountered
encountered
distribution,
although the ion temperature
[Fig. ‘14(a)].
A comparison
changes
dots
of the nighttime
observed
on
day [Fig. ‘13(a)]
on that day [Fig. 6[h)].
9 August
is compared
but no dramatic
in September
1964 (Rrf
and lasted
about 4 days.
of the storm
and the daytime
to have been produced
appear
behavior
and i8-i
in the ion temperature
at nighttime
the commencement
significant
on the storm
with a
Despite
too soon after the sudden
44
to have taken place.
The behavior
began at 0954 f?ST on ‘f 5 September
the time interval
5 days.
on +8 August followed
heating of the atmosphere
seems
B.
of i965 (Ref. 43),
between the daytime temperatures
temperature
2100 to 0300 EST for the nights of ‘t7-i8
again,
also shows little
storms
(SC) at 0840 EST on i8 August and lasting for the following
to he higher
10).
43
Ilcrc
obser”atmns
in the temperature
on the disturbed
for quiet and disturbed
periods
day
[Fig. 14(1>)]
difference.
June
As already
noted,
A sudden commencement
the observations
occurred
made in June were
xt -0600
the most disturbed
EST on 15 June, hut the magnetic
43
for the entire
indices
year’
Ap and K p
I
J---J.
t
,:00
t
,:00$
TEMPERATURE
(a)
o
I
I
,00
I
1800
TEMPERATURE
~)
~g.
13(a-b).
Kp
is mean
Comparison
value
of
Kp
of
index
mean
over
temperature
these
time
~
,;oor
I
Daytime.
I
,200
,
,;OO ~
[°K1
J
I
3000
I
,400
I
leK)
Nighttime.
profiles
intervals.
44
for
quiet
and
disturbed
periods
in
August.
I
sEPTEMBER
,000-,500
$965
EST
M SEPTEMBER
?, = 2-
,5
ij
:}
SEPTEMBER
= 5-
:}
2.0
[
I
1
6.0
0
1
I
1zoo
,,00
TEMPER&TURE
[°K1
I
,400
I
,000
(Q) Daytime.
I
,00
0
(b)
Fig.
14(a-b).
~p is me..
Comparison
of
mean
temperature
I
,*OO
I
)m.
TEMPERATURE
1°K1
I
,..,
,000
Nighttime.
profiles
value of Kp index over these time intervals.
45
for quiet and disturbed
periods in September.
reached
erably
their highest
depressed
sunset.
suggesting
Millstone.
and July.
At nighttime,
on ib June.
Figures
Here,
the electron
15(a-b)
the storm
The electron
density
with that on the 15th [Figs,
density
that the trough of low ionization
had been increased
increased.
values
compared
compare
effects
to anomalously
observed
the average
are clearly
and the electron
[The June values
fell
for the period
around
for the time of year.
45
Alouette
had moved over
and nighttime
temperatures
During the daytime,
reduced.
of Ti are not plotted
on the 16th was consid-
except
low values
by the satellite
daytime
evident.
temperature
observed
6(f) and 8(f)]
At nighttime,
in Fig. i 5(b) because
for .1une
the ion temp~rature
Te and Ti were
both
they fall on the July Te
curve. ]
)0.0
JUNE/JULY
4000!500
1965
EST
.)
I
0
600
I
I
,,00
!,.0
TEMPERATuRE
[-K
I
r
?.00
,00.
I
2.00
I
I
300,
)
(a) Daytime.
,000
wNE(JULY 1965
2100-0300 EST
0
I
em
I
,2,,
I
,,00
TEMPERATURE
[~K1
(b) Nighttime.
fig. 15(a-b).
ComFmrison of mean temperature profi Ies for June
Kp is mean value of Kp index over these time intervals.
(disturbed
days) and July (quiet cloys).
46
---- –—-———i
~.-..-....--...-,*-
C.
Discussion
In agreement
of disturbed
conditions
temperature,
(i. e.,
is to raise
at altitudes
below
nce
with conclusions
to disappear
10
earlier,
the exospheric
This seems
since at this
very
that the principal
temperature,
temperstur.es
clear
altitude
It appears
neutral
where the ion and neutral
about 400 km).
seems
reached
from
are substantially
Fig. 15(a).
the electr’on
daytime
and consequemly
Above
temperature
effect
the iml
the same
-600 km, this differe-
begins
to govern
the
ion
temperature,
A reduction
did occur
to
have
in June t 965.
formed
been
a result,
electron
temperature
chving to the expansion
higher
the electron
than in July,
ceeds
in the daytime
was not observed
of the neutral
in JmIe than in July [compare
density
N ia actually
higher
This would lead to increased
at a rate proportional
local
to N2(Te
– Ti)/T~/z,
maximum
observed
in September
atmosphere,
hut
i 964,
the F-1ayer
appears
Figs. 8(f) and (g) or 9(d) and (e)].
at altitudes
cooling
in the range
of tbe electrons
As
300 to 500 km in June
by the ions,
which pro-
and may account for the decrease
in electron
temperature.
The very
large
evening
that at sunset on both days the layer
tral wind velocity
The very
proposed
or,
as seems
likely,
large,
either
as a result
the action of an east-west
of increased
electric
neu-
‘
field.
low peak electron density observed
on i 6 June prior to sunset supports the view
25
46
Norton,
and others that at midlatitudes
the storm time behavior z-esem -
then often encountered.
the seasonal
anomally,
transition
These
high electron
because
authors
namely,
The June 1965 nighttime
August
height was very
more
to the fact
by Ouncan,
bles the winter-to-summer
very
on $5 and fb June must be attributed
attribute
a decrease
behavior
temperatures
abnormally
the storm
in the ratio
closely
were
low F-region
densities
to the same basic
that observed
in September
are
cause as
of O to Nz (and 02) at F-region
resembles
encountered.
behavior
electron
heights
‘1964 in that
On the other hand, this was not observed
in
[Fig. ?i3(b)]
although the average Kp “alue was 50 in both cases.
We speculate that in June
45
which appears to mark the boundary between the regular midla.titude iono 47
and the irregular
polar region,
moved southward over Millstone.
Norton and Marovich
the ionization
sphere
trough,
have observed
that the trough appears
higti plasma
August
temperatures
exist
to be associated
inside
the trough,
and June nights could be explained
with the midlatitude
If this is the case,
by different
locations
red arc,
and that
the difference
between
of tbe trough with respect
the
to
Millstone.
VIff.
SUMMARY
The Millstone
AND CONCLUSIONS
Hill UHF Thomson
1965 to obtain F-region
were
usually
made for 48-hour
month,
Magnetic
(August
and September)
type behavior
ing months,
previous
density
the magnetic
scatter
densities
periods
radar
evident
prior
was operated
routinely
and ion temperatures.
on the Geophysical
sudden commencements
and immediately
system
and electron
occurred
World
Days near the middle
during two of the observing
to the observations
in June.
only in the case of the June measurements.
activity
was low and the results
throughout
Measurements
differ
little
from
of each
periods
However,
storm-
During
the remain-
those observed
the
(sunspot minimum),
is a midlatitude
beha”ior,
of electron
storm
is clearly
year
Millstone
electron
density
station that exhibits
with a rapid transition
is not accompanied
between
by marked
a characteristic
winter
the two near equinox.
variations
in either
and summer
This
seasonal
the electron
electron
variation
or the ion
47
..—_.._ . .,
. .,,_.__,-_
._
temperatu~c,
The depressed
a change in the neutral
results
is still
composition
lacking.
tYPe of composition
electron
The
change,
density
encountered
of the atmosphere,
storm behavior
but in extreme
observed
although
is thought to rcs!dt
confirnmtim
transport
of the turbopau. sealtitude have both been advanced as mechanisms
from
of this from
in June is thought to represent
Global
t’orm,
in summer
of atomic
oxygen
which produce
Imcket
the same
and changes
this composition
change.
In contrast
behavior
to the uncertainties
of the electron
understood.
Although
onstrated,
employed
we feel
density,
a per?ect
both to higher
mining
to permit
met recently
observations
source
theory
are capable
of the F-region
seems
magnitude
governing
the
reasonably
well
has not yet been demof various
pzrametcrs
error.
of a number of improvements
(b) improvements
and (c) increased
by the construction
the mechanisms
and measurement
the absolute
of remaining
altitudes,
(at low altitudes)
concernit,g
structure
concerning
at Millstone
the ion temperature,
ments were
the thermal
is the chief
and lower
exist
match between
that uncertainty
in the theory
The measurements
tensions
that still
in accuracy
time and height resolution.
of a new spectrum
using short-pulse
analyzer,
autocc>rrelation
including
– especially
(a) exin deter-
Most of these requireand by modifications
methods
measurements,
ACKNOWLEDGMENTS
J. Morin,
and
The invaluable assistance of W. A. Reid, J. H. McNl*lly,
at the Millsmne Hill Radar Observatory in maintaining, modifying, and operating the radar equipment for these measurements is
gratefully acknowledged. R. Julian and ]. Moriello contri!sdted extensively to the data reduction by writing the computer program employed
to analyze the measured signal spectra. J. K. Upham carried out the
computer processing of these data, while the data reduction requiring
handanalysis was chiefly performed by Misses D. Tourigny, F. Angier,
and L, Zak. The constant support of P. B. Sebring is also gratefully
acknowledged.
others
48
-,.._—
of spectrum
REFERENCES
1. J, V. Evans, “Ionospheric Backscatter Observations at Millstone Hill,” Technical
Report 374, Lincoln Laboratory, M. 1.T. (22 Jm.ary 1965), DDC AD-6166~7.
2. —,
“Millstone Hill Thomson Scatter Results fOI 1964,” Technical Report 430,
Lincoln Laboratory, M. 1.T. (15 November 1967), DDC AD-668436.
3.
—,
Planet.
Space Sci.
~,
DDC AD-616607.
1031 (1965),
‘4, _,
Planet. Space Sci. ~,
5. _,
J. Geophys. Res. ~,
1175 (1965), DDC AD-61431O.
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J. Geophys. Res. ~,
4331 (1965), DDC AD-623606.
7,
_,
8. —
9.
_,
Planet. Space Sci. ~,
1387 (1967).
1557 (1967).
, J. Geophys. Res. u, 3489 (1968), DDC AO-673605.
J. Geophys. Res. 7Q, 131 (1965), DDC AD-613886.
10.
, J. Geophys. Res. ~,
11. _
and L,P, Cc,.x, J. Geophys.
2726 (1965), DDC AD-621233.
7&, 159 (1970), DDC AD-703492.
Res.
12. G. R. Thomas and F.H. Venahles, J. Atmos. Terrest.
13. A. L. Schmeltekopf, F. C. Fehsenfeld,
Sci. Q, 401 (1967).
14. G, R. Thomas, J. Atmos. Terrest.
62~ (1967).
G. 1. Gilrnan and E. E. Ferguson, Planet. Space
Phys. a,
15. H. Kohl and J.W. King, J. Atmos. Terrest.
16. H. Kohl, J. W. King and D. Eccles,
phys. ~,
1429 (1968).
Phys. ~,
1045 (1967).
J. Atmos. Terrest.
Phys, ~,
1733 (1968).
17. D. F. Strobel, ,0. the Ionospheric F2-Layer and Its Maintenance at Night by Thermospheric Winds ,“ PhD. Thesis, Department of Applied Physics, Harvard University (1968).
18. D. L. Sterling, W. B. Hamon, R.]. Moffett and R. G. Baxter, Radio Sci. ~, 1005 (1969).
19. J,V. Evans and I.J. Gastmin, J. Geophys. Res. ~,
20. A. F. Nagy, P. Bauer and E. G. Fontheim,
807 (1970).
J. Geopl,ys. Res. L?, 6259 (1968).
21. W, Rishbeth and C. S. G. K. Setty, J. Atmos. Terrest.
Phys. a.
263 (1961).
22. J. W. Wright, J. GeoPbYs. Res. Q, 4379 (1963).
23. W. Becker, Electron Densify Profiles in tie Ionosphere and EXOSP&S.
(North-H.lland Publishing Co., Amsterdam, 1966), p. 218.
‘
24. J. V. Evans, ]. Geophys. Res. ~,
3343 (1967), DDc AD-658912.
25. R. A. Duncan, J. Atmos. Terrest.
Phys. Q, 59 (1969).
J. Frihagen, ed.
26. P. Waldteufel, personal communication (1969).
27, G. Vasseur, J. Atmos. Terrest.
Phys, ~,
28. _,
Phys. (in press,
J. Atmos, Te,re$t.
397 (1969).
1970).
29. H. cam-u, M. Petit and P. Waldteufel, J. Atmos. Terrest.
30. R, H. Wand and F. W. Perkins, J. Geophys. Res.
~,
31. J. V. Evans and G.P. Mantas, J. Atmos. Terrest.
32. E.G. Fontheim, A.E. Beutler and A.F.
Nagy,
Ann.
Phys. ~,
6370 (1968).
Phyi. 30, 563 (1968).
Geophys. ~,
489 (1968).
33. M. L. Duboin, G. Lejeune, M. Petit and G. Weill, J. Atmos. Terrest.
34. J. S. Nisbet, J. Atmos. Terrest.
Phys. Q,
351 (1967).
Pbys. 3!!, 299 (1968).
1257 (1968).
35. A. F. Nagy, E, G. Fontheim, R. S. Stolarski and A. E. Beutler, J. Geopbys. Res. ~,
4667 (1969),
I
36. A. Dalgarno, M. B. McElroy and J. C. G. Walker,
37. A. Dalgarno, hi. B. McElroy,
1371 (1968).
Planet. Space Sci. ~,
331 (1967).
M.H. Rees and J. C. G. Watker, Planet. Space Sci. @,
38. P.M. Banks and A. F. Nagy, J. Geophys. Res. ~,
49
1902 (1970).
39.
R. J. Cicerone
40.
B.C. Narasinga
41. R. J. Cicerone,
and S. A. Bowhill,
Radio Sci. ~, 49 (1970).
Rao and E.J. R, Maier,
]. Geophys. Res
Phys. ~,
J. Geophys, Res. 7J, 975 (1966).
VIII,
800 (1968).
—
45. D. B. Muldrew, J. Geophys. Res. ~, 2635 (1965).
44.
L. G. Jacchia, Space Res.
46, R.B.
47.
1970).
private communication (1969).
42. J. E. Geisler and S. A. Bowhill, J. Atmos. Terrest.
43. J, V. Lincoln,
(in press,
Norton, Proc. IEEE g,
1147 (1969).
R. B. Norton and E. Marovich, Proc. IEEE ~,
1
,.,’
50
1158 (1969).
119 (1965).
. . . . .... . .. . . .... . ... ..
00CUMENT
(Sawrl,,
1.
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.l.,sl!l
NO
<s.!,.”
L. CT, VtTY
of ,1,1.,
b.adr
(Cormrate.wth
.[
ebe,,..,
and
CONTROL DATA - R&D
Indexing
Mmofe,
ion must
b.
entered
or)
2..
when
the
..,0,,
overall
raw?,
,EC”,,
T”
i.
CIa$elfied)
CL ASS,
F3CATION
Unclassified
Lincoln Laboratory,
M. 1.T.
2b. 0.0”,
None
3. REPORT TITLE
Millstone Hill Thomson Scatter Results for 1965
$. IJ.SC.(P7,VE .o’r E5 (Type 01mporlandincl.sfve dales)
J
Technical Report
,. AU?. O.<S1(L.. * “m*, f,rel “m., i.ll;.W
Evans, John V.
i
7..
,, REPORT OATS
TOTAL
NO.
8 December 1969
9.,
3.,
,.
CONTRACT
,FZOJECT
OR
NO.
GRANT
0,
,..,
s
7b.
NO.
OF
NO.
QRIGINATOR>S
AF 19(628)-5167
REFS
4?
56
REPORT
‘
NUMBER(S)
Technical Report 474
649L
,h.
OTHER
REPORT
assjgned
. .
this
.0(S1
{A,!,
ofhecoumber.
that
ma,
be
ra.oort)
ESD-TR+9-3S7
d.
!0. .v.l..,,
LITY/., ulT10l0.
PJO,lcE5
This docwr+ent has been approved for public release and sale; its distribution is unlimited.
1. 5UPPLEME.T&RY NOTES
,2,
Ae,
MILITARY
ACTIVITY
Air Force Systems Command, USAF
None
,.
sPONSOR(NG
TRAc,
This report presents F-region electron densities, and electron and ion temperatures observed
during the year 1965 at the Millstone Hill Radar Observatory (42. 6°N, 71.5° W) by the UHF Thomson
(incoherent) scatter radar. The measurements were made over 48-hour periods that were usually
scheduled to include tie International Geophysical World days near fbe center of each month. Geomagnetic storm sudden commencements occurred during two of the observing periods, but do not
appear to have giVen rise to marked variation of fhe densities or temperatures,
On the ofher hand,
measurements made during the progress of a major storm (15-19 June 1965) exhibit large changes
compared with fhe behavior observed in fhe following month. The remaining
months were magmetical.ly quiet, and tie density and temperature
behavior were similar to those observed in 1964.
Millstone is a midlatitide
station exhibiting a characteristic
“winter” and “summer”
daytime density
variation.
The transition between tlwse two types occurs rapidly around equinox, without any corresponding seasonal change in the F-region thermal structure. Current ideas concerning the mechanisms responsible for fhis and other features of diurnal and seasonal variations are discussed.
1,
KEY
‘//0.0S
Millstone radar
F -region
diurnal variations
electron density
ionospheric scatter
seasonal variations
5i
temperature effects
spectrum analyzers
UNCLASSIFIED
Security Classification
. --- .—.,
—-z