GEOPHYSICAL INSTITUTE

of the

UNIVERSITY OF ALASKA

Final Report

Grant NCR "02-001-099, Supplement No. 2

Prepared for

National Aeronautics and Space Administration

and Presented as two papers

to IAGA, Sept. 1973

February 1974

G. G.Principal Ivestigator

Keith B. MatherDirectorGeophysical Institute

(HaSArCR-138156) M E A S U R E M E N T S OF OPTICALAHD M I D D A Y A U R O R A S (Alaska Univ.,|Fairfcanks.) 43 p HC $5.25 CSCL- 04A

H74-22036THRUH74-22038Dnclas

_G3/A3__37_08.6_

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7

COORDINATED ANALYSIS OF AIRBORNE SPECTROPHOTOMETRIC MEASUREMENTS

FROM THE MID-DAY AURORAS . ' ;,

G. G. Sivjee .Geophysical InstituteUniversity of AlaskaFairbanks, Alaska 99701

Early in 1968 and again towards the end of 1969, the National Aeronautics

and Space Administration of USA sponsored a total of forty-two .air flights in

mid- and high-latitude areas specifically for studying atmospheric emissions

from the nightglow and the aurora, as well as events related to magnetic

substorms. Several universities and national as well as industrial research

laboratories participated in these .missions, employing a sophisticated

array of photometers, spectrometers, all-sky cameras, TV cameras, radiometers,

riometers and magnetometers to monitor various high altitude atmospheric

phenomena from an airborne platform. While some participants in the expedition

have reported their findings in the literature, little effort has been expended

in correlated analysis of the massive wealth of data gathered from the airborne

measurements. The aeronomy group at the Geophysical Institute of the University

of Alaska is currently attempting such correlated analysis under a NASA

rsearch grant, and this morning I would like to present to you some preliminary

results of our efforts in this area. .

The data we have analyzed so far come from a half meter Ebert spectro-

photometer, several fixed and tilting interference-filter photometers and

all-sky cameras. In particular, we have looked at measurements made with/:.,

these detectors .in the mid-day auroras and compared them with similar

measurements from the night-time auroras. Figure 1 shows a single scan

output of the spectrometer taken around.Fort" Churchill in a westward, travelling

surge. This spectrum of the auroral emissions in the 3000 to 4000 A is a

representative sample of the several hundred spectra in this wavelength region

obtained in night-time auroras. The most prominent auroral emission features

in this UV spectrum are the N ING, the N 2PG, and N_VK bands as well as some

atomic oxygen and nitrogen lines. Please note the relative intensities of the

(0-0) and (1-1) bands of N«ING system in this spectrum. It is apparent that

the (0-0) band is many times brighter than the (1-1) band, in conformity

with the ratio of population-weighted Frank-Condon factors for the transitions

involved. To demonstrate this more clearly nine scans were summed to obtain

the spectral profiles of the N»ING (0-0) and (1-1) bands shown in Figure 2.

The solid curve is the observed auroral spectrum while the dashed curve

represents a synthetic spectrum constructed assuming 5A resolution for the

spectrometer and vibrational and rotational temperatures of 0 and 250°fe

respectively. While no elaborate care has been taken in comparing the two

spectra, a simple visual matching shows that the observed intensity distri-

bution of these two bands do indeed correspond to the case where all N-

molecules are in the lowest vibrational level and the rotational levels of

the electronic ground state are populated according to a Boltzman distribution

characterized by a rotational temperature of about 250°K. The ratio of the

population weighted Frank-Condon factors for the transitions which produce

the (0-0) and (1-1) bands of N ING is approximately 24.

I would now like to discuss some of the data obtained from the mid-day

auroras. During two flights from Norway to Greenland and back, the aircraft,

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mid-day section of the oval. An all-sky camera picture of one such aurora

observed at 0845 around IL 80° (Geog. lat. = 79°, Long. = 25°W) is shown•i

in Figure 3. The airplane was flying along a direction slightly north of

west, and the zenith detectors scanned across the auroral patches, shown here,

as the aircraft passed under these auroras. Measurements made with a fixed

multichannel photometer, having the same field of view as the spectrometer,

are presented in Figure 4 which shows the variations in the intensities of the

green and red lines of atomic oxygen as well as the intensities of the N?ING(0-1)

and N^ZPG (0-0) bands. These measurements were made over the area spanning

the invariant latitude from approximately 75° to 82°. Judging by the

relative intensities of the emissions monitored and the morphology of magneto-

spheric charged particles reported in the literature, we infer that the flight

path crossed over from the trapping region through the trapping boundary and

into the cusp region. The ratios of 6300 to 5577 and 4278 changed from about

0.4 and 2.7 equatorward of the trapping boundary to 1.3 and 9.0 in the trapping

boundary and thence to 4.4 and 25.9 in the cusp region. The dashed lines in

Figure 4 enclose the region in which the N.ING band measurements from the

half-meter spectrometer were averaged. Before presenting these measurements,

I would like to show the data from several tilting photometers taken in this

same aurora. Figure 5 presents the variations in the intensities of the

red and green line of atomic oxygen, the Balmer B .line of atomic hydrogen

and the (0-1) band of N.ING. The geometrical shadow height, which varied

from 270 km to 370 km in the period bounded by the dashed line,.is also

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shown. The solar depression angle varied from about 16° to 19° during

the time in which the spectral data were averaged. Also, please note the

appearance of hydrogen emission during this period; the Ik brightness in the

cusp region attained a peak value of about 10R.

Two spectra of the auroral optical emissions, in the 3000 to 4000A '

region, from a mid-day aurora are shown in the next Figure 6. Comparing the

relative intensities of the (0-0) to (1-1) bands we see that this ratio is

much smaller than the value of about 24 found in the night-time auroras. This

is more clearly seen by adding several spectra and displaying only these two

bands. The next diagram (Figure 7) shows the result of adding, all spectrometer

scans obtained between TL 76.5° and 81°. Comparing the intensity of the (1-1)

band to the (0-0) we clearly see a relative brightening of the (1-1) band in

the mid-day aurora. The ratio of the (0-0) to (1-1) band intensities is about

8, i.e., a factor of 3 lower than the value observed in the night-time

auroral spectrum shown earlier. In an attempt to determine the rotational

temperature of the (0-0) band we have constructed synthetic spectra of the

N-ING (0-0) and (1-1) bands at various rotational temperatures for a fixed

vibrational temperature of 0°K. One such synthetic spectrum at 3500°K is

shown in Figure 7. Clearly the rotational temperature of the first

negative bands of N is higher than 3500°K and the vibrational temperatures

of N? must be much higher than 0°K at atmospheric altitudes where optical

emissions from mid-day auroras peak.

In attempting to understand the mechanism which causes such an anomalous

intensity distribution of the N_ING bands we note from Heikkila and Winningham's

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measurements of the particle flux in the cusp region that during magnetically

quiet periods the electrons have characteristic energies of around 100 to

200 eV while the proton energy, is between 300 eV and 1 keV. These particles

will be stopped in the F region where most of the optical emissions in mid-day

auroras must therefore originate. This inference is supported by the airborne

photometric observations showing high ratios of 6300 to 5577 and 4278 in mid-day

auroras. The high altitude of these auroras suggests several mechanisms

which could produce an intensity distribution of N ING bands markedly different

from the values observed in the relatively low altitude night-time auroras.

A 5 6Calculations made by Walker et al. , Jamshidi , and Bauer et al. ,

predict a vibrational temperature of N. ground state much higher than the

translational temperature in the lower thermosphere. Recent calculations of

Breig et al.... which take into consideration the effect of quenching of N.

by atomic oxygen give values ranging from 800 to 2200° for the vibrational

temperature of N? in the 200 to 300 km altitude region of the atmosphere.

To find the N- vibrational temperature which would produce a ratio of g .

between the, intensities of N-ING (0-0) and (1-1) bands we have calculated

the ratios of the population-weighted Frank-Condon factorjfor these

emissions and the results are displayed in Figure 8. The observed

ratio of about 8 in mid-day auroras corresponds to N« vibrational temperature

of around 2600°K. However, as we saw in the last diagram,, the observed

rotational temperature is in excess of 3500°K whereas the translational

temperature in the F region is about 800°K. Hence, while this effect may

12

Figure 8

13

contribute to the lowering of the (0-0) to (1-1) band-intensities ratio,

it cannot increase the rotational temperature from 800° to more than 3500°K.

A second mechanism is resonant scattering of solar radiation. Vallance

Jones and Hunten observed a ratio of 100?2fi for the intensities of the

(0-1) --and (1-2) bands of N-ING in sunlit auroras peaked around 400 to 500

km, compared to the ratio of 100:11 for non-sunlit aurora. Relative to the

(0-1) band the intensity of the (1-2) band was higher by a factor of 2 in

sunlit aurora and the rotational temperature was around 2200°K. On the

9other hand Broadfoot and Hunten in their studies of the twilight emissions

of NjING (0-0) and (1-1) bands, peaking around 255 km , did not observe a

very drastic change in the ratio of the (0-0) to (1-1) band intensities and

the (0-0) band profile fitted a synthetic spectrum for 1600°K. Satellite

2 • • ' "particle data from the cusp region as well as the observed ratio of 6300

to 4278 in mid-day auroras suggest that the auroral particles in this region

penetrate down to 200 km ., while the shadow height was above 270 kms. This

fact, coupled with the vibrational and rotational temperatures of N. in

mid-day aurora that are observed to be much higher than those found by

investigators in the cases involving resonant scattering of solar

radiation, suggests that resonant scattering may not be the sole source

of the N.ING emissions in mid-day auroras.

Another likely mechanism is that of excitation by slow ions. Earlier I

2mentioned that Winnigham and Heikkila observed l.keV protons in the cusp

region and the airborne photometer measurements in mid-day auroras detected

about 1OR of Hg in the mid-day auroras. Using Eather's value of 1 Hi photon

Q O

for every 10 protons we get a flux of 10 protons/cm, /sec. With such a

2" +large flux of protons it is feasible to excite enough N_ into the B E

state of N« to produce a detectable intensity of N ING emissions. Moore

and Doering's laboratory measurements of the ratios of the N^lNG band as

a function of proton energies predict an intensity ratio of 12 for the (0-0)

to (1-1) bands excited by 1 keV protons. The observed intensity ratio

corresponds to excitation by protons with energies of 100 to 350 eV. This

does not contradict the satellite measurements which show proton energies

of 1 keV since such protons may be more effective in exciting ING bands

when they have slowed down from 1 keV to several hundred electron volts.

Moore and Doering also observed a rotational temperature of 3500°K in

ion excited N21NG bands. However, this high temperature applies only to

rotational levels with K values of greater than 22, the lower rotational^ ' " " . -

levels giving much smaller rotational temperatures. On the other hand, the

mid-day auroral observations show very high rotational temperatures even for

low rotational levels.

At this stage of analysis it is difficult to single out the most important

mechanism for the N-1NG emissions in mid-day aurora. Further analysis of this

data together with other measurements from a couple' of other flights in the

cusp region may enable us to determine the relative significance of each of

the three mechanisms, discussed here, in the mid-day auroras. .

15

REFERENCES .

1. G. G. Sivjee, Analysis of Auroral Data from NASA's 1968 and 1969

Airborne Auroral Expeditions, Semi-Annual Report on NASA/AMES Grant

No. NCR 02-001-099, Suppl. No. 1, Geophys. Inst., Univ. of Alaska, .... ...

June, 1973. . . . '

2. W. J. Heikkila and J. D.,Winningham, Penetration of magnetosheath

plasma to low altitudes through the dayside magnetospheric cusps $

J. Geophys. Res., \7JL» 883 (1971).

3. M. H. Rees, Note on the Penetration of Energetic Electrons into the

Earth's Atmosphere, Planet. Space Sci., 12, 722 (1964).

4. C. G. Walker, R. S. Stolarski and A. F. Nagy, The Vibrational Temperature

of Molecular Nitrogen in the Thennosphere, Ann. Geophys., 25, 831 (1969).

5. E. Jamshidi, Vibrational Temperature of N. in the E and F region, Master's-" \ • • - . . •

Thesis, Wayne State Univ., 1971.

6. E. Bauer, R. Kummler and M. H. Bortner, Internal Energy Balance and

Energy Transfer in the Lower Thermosphere, Appl. Optics,'J.O, 1861 (1971).

7. E. L. Breig, M. E. Brennan and R. J. McNeal, :Effect of Atomic Oxygen on the

N- Vibrational Temperature in the Lower Thermosphere, J. Geophys. Res.,

28, 1225 (1973).

8. A. Vallance Jones and D. M. Hunten, Rotational and Vibrational Intensity

Distribution of'the First Negative N2 Bands in Sunlit Auroral Rays, Can.

J. Phys., 38, 458 (1960).

9. A. L. Broadfoot and D. M. Hunten, N- Emission in the Twilight, Planet.

Space Sci., 14, 1303 (1966).

16

10. R. E. Eather, Auroral Proton Precipitation and Hydrogen Emissions, Rev.

Geophys., 5_, 207 (1966).

11. J. H. Moore, Jr., and J. P. Doering, Vibrational Excitation in Ion-Molecule

Collisions: H , H-, He , N , N , and Electrons on N-, Phys. Rev., 177,

218 (1969).

17

A) .

. OPTICAL AURORA AND ITS RELATIONSHIP

TO MEASUREMENTS FROM SATELLITES,

VHF RADAR AND INCOHERENT SCATTER RADARS

. G. J. Romick

Geophysical InstituteUniversity of AlaskaFairbanks, Alaska 99701

Invited Paper given at the LAGA General Assembly in Kyoto, Japan,September 10-21, 1973 . .

INTRODUCTION 'Papers previously presented in this session and in others yesterday

have discussed many different coordinated programs and their results.

Here, I will attempt to classify the types of coordinated programs that

are possible and illustrate some of them with a few examples that have

taken place in Alaska during the last few years.

In general there are three classes of coordinated programs.

Each is illustrated in Table 1, listed in .order of increasing rela-

tionship between the cooperating groups or individuals. Coincident

data acquisition programs refer to the gathering of data from different

instruments which by chance were operated during a particular event.

The resultant analyses combine the available data to more completely

describe the event. Much of the past analysis of ground and satellite

data or satellite to satellite data falls in this category. Although

at times frustrating and time consuming, the results of these types of. • •'. 9

coordinated analyses are quite useful.

Scheduled data acquisition from numerous instruments in operation

requires collaboration among individuals prior to the occurrence

of a particular event. Many of the coordinated studies today use this

scheme. Satellite emphemeris data are made available to ground based .

experimenters and coordination of ground observations with known

rocket launches, aircraft flights, and satellite overpasses are planned.

Similarly, involvement of radars, and other instruments used to record

magnetic activity are included in this type of program before a particular

series of observations. . . . . • . . \ • .

.Planned experiments represent the direction of.future.programs..

19

Large scale programs involving the coordination of- different groups

to attack specific problems are being planned and observations using.

•

specific instruments for specific information are being contemplated.

The A-E satellite illustrates this concept. The whole space shuttle

observatory concept is being planned using this approach not only on

board the satellite, but between the satellite and ground stations as

well. As examples of some of these types of .programs I will present

some that have occurred in recent years and describe one particular study

in somewhat greater detail.

Figure 1 illustrates the various major facilities in Alaska used

for auroral studies in the last few years. Other ground stations north

of Fort Yukon are not indicated on this map but also provide routine

data such as all-sky camera photographs, 3 component magnetometer observa-

tions and riometer information primarily under the guidance of various

principal investigators at the Geophysical Institute. There are also

many geophysical parameters measured at the Institute that are not

included in this figure but which aid in the assessment of the geophysical

environment surrounding a particular event.

In many ways it is obvious that the operation of all of the facilities

indicated in Figure 1 to their maximum capability would require an enormous

staff. In this regard it is of interest to note in Table II the various

groups which through the 1971-1973 period have been active in coordinated

studies using these facilities. Not all of these groups have made simul-

taneous measurements and even within .this small community some of the

interrelationships fall under the coincidence category. However, the

expertise, equipment and funding represented by this group is certainly

20

larger than that of any single organization and the need for coordinated

efforts is plain.

Discussion of-Various Programs

In many of the studies associated with the various facilities in

Alaska, we use optical triangulation techniques to determine the position

of the aurora in order to place the other measurements in the perspective

of the overall auroral morphology (Romick & Belon, 1967). The optical

data used for this purpose is either that from the meridian scanning

photometer at one of the prominent auroral emissions (5577 01 or 4278 N?),

or the All-Sky Camera. Figure 2.shows the simple triangulation geometry in

a geomagnetic meridian plane through two stations and illustrates how both

height, latitude and perhaps even the vertical luminosity profile can be ob-

tained The use of this technique is illustrated in Figure 3, where we

have plotted the location versus time of all discrete peaks of auroral 5577 01

luminosity seen along the meridian on March 9, 1972. Also indicated are

the times when either rockets or satellites acquired data in the vicinity

of the field stations. The local magnetic K index is also indicated.

Notice that one can immediately tell in what type of activity the events

occurred and what type of auroral activity immediately preceded or followed

the measurements. Poleward and equatorward expansions in the evening .

sector are obvious in this type of plot.. Another example of a different

day is shown in Figure 4. The equatorward motion and rapid poleward expansion

are quite easily seen. Figure 5 shows the all-sky camera pictures covering

the same period as in Figure 4, and illustrates that the rapid poleward

expansion was due to a westward traveling surge moving through the meridian.

Figure 6 shows the relationship of the Chatanika Incoherent Scatter Radar

in this event to the visual aurora. The amplitude of the electron density

21

is plotted along the field line intersection with the radar beam and

shows how well'-the peaks in electron density match the auroral forms

within the beam throughout the period. We are still in the process of

comparing the details of the electron density to the observed optical

data at various wavelengths.

Another type of study is shown in Figure 7, Romick and Sharp 1972.

This illustrates a satellite pass across Alaska and the regions of

precipitation measured by the satellite. The oval was deduced by the

ground.magnetometer data. Optical 3, 4278, 5577, and 6300 data from

the ground were also obtained. Figure 8 shows the energy flux detected on

board the satellite, and illustrates the typical evening sector morphology

relating the incident protons and electrons across the oval and the

position of the > 130 kev electron trapping boundary. From these

satellite proton data we have calculated the H0 intensity which should .be

observed. Figure 9 compares the calculated values with those actually seen

after correction for scattering, extinction and path length effects.

The relationship is quite good and indicates that.present theory is ade-

quate to explain the emission considering the present state of our ability

to perform absolute calibrations of both particle detectors and optics

independently. .

Another type of coordinated experiment in which numerous instruments- f . ' • ' •

participated occured on March 16, 1972 Hunsucker, et al., 1972. Figure 10 .

contains a portion of the data that-shows the comparison of the electron

density measured by AFCRL on a rocket by two different techniques and that

measured by the Chatanika incoherent scatter radar. As seen, the comparison

is quite good over the whole altitude range. There are many other coordinated

studies that are going on involving the various groups previously indicated. . .

• ' • • : ' ' . 2 2 - : • • ' ' • ' " • ' . . ' . , •

The remainder of this presentation will concentrate on one preliminary

study, in which I am particularly interested. It involves coordination .

of the analysis of data from a satellite, V11F radar and optical and

magnetic observations, C^omick, et al 1973. Figure 11 presents six all

sky camera photographs during.the passage of satellite 1971-89a which

was instrumented with particle detectors by Lockheed Palo Alto Research

Laboratory. Of particular interest here is the >130 kev electron detectors

and the C and I boundaries which refer respectively to the cosmic ray

background and the boundary where the 20 and 90 pitch angle detector

fluxes were equal (isotropic). The radar echo is that obtained by the

.50 mHz NOAA radar in Anchorage. The optical data were obtained by the

Geophysical Institute at Ester Dome or Fort .Yukon, Alaska. During the

spring of 1972, there were nine simultaneous radar-satellite events

and in all cases the radar echo was equatorward of the C trapping

boundary. On three events, the range in the diffuse echo lay between the

C and I boundaries. Notice the difference in position of the C boundary

on the different All-Sky camera prints in Figure 11. On March 7, the

boundary lies just equatorward of the bright arc and so also does the

radar echo. On March 16, however, the C boundary and echo lie far equatorward

of the bright arc. On other days the relationship is not as clear but

the echo always appears equatorward of the. C boundary.. We can see this

more clearly on the map type presentation shown in-figure 12, for March 7,- a " . - . . .

9, 14 and 18. To study these events further, we decided to investigate^

the relationship of the trapping boundary position to substorm activity

and DST. Figure 13 illustrates our findings with these preliminary set

of data. The invariant latitudes of .the C boundary .plotted vs. Q midnight

23

or Q indicates a possible relationship with before and after westward

surge activity but the basic problem with the use of K type of indices is

shown. One can have either high or low values of Q or K with high negative

values of DST, and thus some confusion may occur. In contrast, the plots

bf'C and"I""Boundary position with DST indicate a clear substorm related

effect in that for a given value of DST the position of the trapping

boundary moves poleward after the expansive phase of the substorm. To

us this implies that the motion of this boundary is .a dynamic feature of

the substorm and we feel that the use and correct interpretation of the VHF

radar may allow us to follow this dynamic motion within individual events.

CONCLUDING STATEMENT

I have tried to illustrate through individual examples some of

the results available in coordinated programs which involve satellites,

radars ground optical instrumentation, and other types of observing

facilities. I hope it is clear to everyone that it will take more of these

types of programs to solve the basic problems in the study of atmospheric

and magneto-spheric geophysics. "

24

Table I

1) COINCIDENCE DATA ACQUISITION

2) SCHEDULED DATA ACQUISITION

3) PLANNED EXPERIMENT

COMBINED ANALYSIS

COORDINATED PROGRAMS•

COORDINATED COOPERATIVE PROGRAMOF DATA ACQUISITION AND ANALYSIS

25

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26

Romick, G. J. and A. E. Belon, Spatial variation of auroral luminosity,

Plan. Space Sci., 15, 475-493, 1967.

Romick, G. J. and R. D. Sharp, Correlations of satellite and ground obser-

vations of aurora on February 19, 1972 SA-53, Transact AGU, 53, November

1972. . . ':..,

Romick, G. J., W. E. Ecklund, B. Balsley, R. Greenwald and W. Imhof, The

interrelationship between the > 130 kev electron trapping boundary,

diffuse VHF radar echoes and the visual aurora, J. Geophys. Res.,

in press, 1974.

Hunsucker, R. D., A. H. Steinfeld, G. J. Romick, A. .E. Belon, H. F. Bates,

W. L. Ecklund, B. B. Balsley, R. A. Greenwald and R. Tsunoda, Structure

and dynamics of ionization and auroral luminosity.during the auroral

display of March 16, 1972 near Chatanika, Alaska, SA-48, Transact 64,

53, November 1972..-.. . .... ... . .,,,.,:

27

Figure 1. Schematic representation of the distribution of various scientific

facilities in Alaska

Figure 2. Triangulation geometry illustrating how the height, latitude and. /

volume emission rate within an aurora can be deduced from two

stations along a geomagnetic meridian. -

Figure 3. Latitudinal positions of discrete aurora plotted versus time on

March 9, 1972. Also indicated are the times of closest approach

of two satellites and the times at which rockets were launched

from Poker Flat Range.

Figure 4. Latitudinal position of discrete aurora plotted versus time on

February 17, 1972.

Figure 5. All-sky camera photographs showing the development of a substorm

as seen in the evening sector at Ft. Yukon, Alaska, corresponding

to the time interval illustrated in Figure 4.

Figure 6. The Chatanika Incoherent Scatter Radar observations of electron

density along the radar beam in the aurora observed in Figure 5.

The amplitude of the electron density is plotted along the field

line intersection the radar beam. The aurora is between the

vertical lines.

Figure 7. Relationship between the observed electron and proton particle

precipitation and the position of the statistical oval for the

STP-71a Satellite pass on 19 February 1972 (Romick and Sharp,

._ 1972)... . •".

Figure 8. Total proton and electron energy fluxes observed as a function

of geomagnetic latitude for the satellite pass .in Figure 6

Figure 9.- Calculated (thin line).and observed (solid line) H8 intersecting

.. with corrections for path length, atmospheric extinction and

scattering . (dots) calculated data used the proton fluxes in -' ..••-•..

: . - Figure.8. ' ' . • • ' • ' . . -;•'. '-.-•''•.•,.? ''• .. / .,' '.' ~'/•'.

Figure 10. . Electron density measured as a function of altitude by rocket11-

techniques and simultaneous Incoherent Scatter Radar (Hunsucker

et al., 1972).

Figure 11. All sky camera data showing the relationship between the > 130 •

kev electron boundaries £ and J^ the 50 mHz radar echoes and the

visual aurora. On March 7, the lower border of the aurora north

of the zenith is outlined. On March 14, the £ boundary is north

of the field of viev of the camera. The ;white dots in the S, .SW

and SE at Ft. Yukon and Ester Dome are reflections off the plastic

dome (Romick et al., 1973).

Figure 12. Maps, of the relationship between the observed positions of the

trapping boundaries for > 130 kev electrons, 50 mHz radar echoes,

and the actual position of visible aurora at 110 km (Romick et al.;

1973). ,

Figure 13. Plot of the invariant latitude of the 130 keV trapping boundaries

[cut off (C) and isotropic (I)] versus magnetic indices using data

from magnetic midnight (Q) or local region (Q ) and DST and

divided into before (circles) and after (dots) westward traveling

surge activity (Romick et al., 1973). •

Satellite

Figure 1. Schematic representation of the distribution of various scientific

facilities in Alaska '

LATITUDINAL VARIATION, p

200km.

100 km

A

HEIGHT (h)

EARTH SURFACE

64 COLLEGE

2.0

1.5

0.5 -

65° - 66° FT YUKON 67°GEOMAGNETIC LATITUDE, 9

2.0

1.5

<.o

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30 60 90

COLLEGE

90-60 30 0

FT. YUKON

Figure 2. Triangulation geometry illustrating how the height, latitude and

volume emission rate within an aurora can be deduced from two

stations along a geomagnetic meridian. .

1500

1430

1400

1330

1300

1230

1130

1100

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MARCH 9. 1972257° East Geomagnetic Longitude

1 1

• . PFNT-33

AMEL-4

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62 63 64 | 65 66 f 67 68 69EDO FTYGeomagnetic Latitude (Dipole)

70 72

Figure 3. Latitudinal positions of discrete aurora plotted versus time on

March 9, 1972. Also indicated are .the times of-closest approach

of two satellites and the times at which rockets Xv-ere. launced

from Poker Flat Range. . ...

1000

0930

•0900

£i-"5 0830env_<D

0800

0730

0700

February 17, 1972257° East Geomagnetic Longitude

66 t 67FTY

68 69 70

Geomagnetic Latitude (Dipole)71

Figure A. Latitudinal position of discrete aurora plotted versus time on

February 17, 1972. ; ' . \ ' ' • ;

XCD

0

72

0800

0858

0917

0901

February 17, 1972Ft. Yukon, Alaska

U.I

0830 0849

0908

0855

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0921 0925- 093

Figure 5. All-sky camera photographs showing the development of. a substorm

as seen in the evening sector at Ft. Yukon, Alaska, corresponding

to the time interval illustrated in Figure 4.

\

O9I6 - OiKV U r O9 l - o*'6~ a r.

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Figure 6. -The Chatanika Incoherent Scatter Radar .observations of electron

density along the radar beam in .the aurora observed in Figure 5.

The amplitude of the electron density is plotted along the field

line intersection, the radar beam. The aurora is between the '

vertical lines. . " • .. - . . . . . . . . - .

Figure 7. Relationship between the observed electron and proton particle

precipitation arid the position of the statistical oval for the

STP-71a Satellite pass on 19 February 1972 (Romick and Sharp,

1972).

Projection of SatellitePath along GeomagneticField to Earth Surface

.1.25

o

1.00

I

§75

I0)

-50.50

Jli

dp Latitude 64.5°. 6 ' 65.5° 66° 66.5° , 67° 67.5° 66° 685° 69° 695° 70°

UT (sec) 62 52 42 -32 22 12 34002 92 82 72 . 62 52

. 09:27:02 UTFigure 8. Total procon and electron energy fluxes observed as a function

of geomagnetic latitude for the satellite pass in Figure

Extinction and Path LengthCorrected Ground Observations of Hft

20°

Scattering Corrected

from Satellite Proton Data\ i i i

d p - L a t i t u d e . 63.5° 64° 64.5° 65° 65.5° €6° 66.5° 67° 675° 68° 68.5° 69° 69.5° 70°UT ( sec) 34082 72 62 .52 42 .32 22 12 34002 92 82 72 62 39952

09'27.'O2 UT

Figure 9. Calculated (thin line)'and observed (solid line) H3 intersecting

with corrections for path length, atmospheric extinction and

-...-• scattering (dots) calculated data used the proton fluxes in

. Figure 8. ,

ICO

130

O 120

110

100 —

so

1C r.'.Af.CM i«J72

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cl) A v

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NUMBER DENSITY PER cm

105

3 :

Figure 10. Electron density^measured as a function of altitude by rocket

techniques and simultaneous Incoherent Scatter Radar (Hunsucker

et al., 1972).

1972

ESTER DOME FT YUKON

March 70904 UT

March 140846 UT

March 180825 UT

March 90941 UT

March 160927 UT

April 70808 UT

RadarEcho

Geomagnetic

Figure 11. All sky camera data showing the relationship between the > 130

. kev electron boundaries £ and £, the 50 mHz radar echoes and the

j visual aurora. On March 7, the lower border of. the aurora north

of the zenith is outlined. On March 14, the £ boundary is north

of the field of. view of the camera. The white dots in the S, SW

and SE at Ft. Yukon and Ester Dome are reflections off the plastic

; dome (Ro;nick et al. , 1973) ... ,, . : .

\ \ x-MO km Satellite Track

Radar Az.\ no kmSatelliteJrack ."

Ft

Bright Auroral Arc .

:BrightStructured Glow

March 9, 1972 —0941:19 UT

March 7, 19720903:52 UT

168° 160° 152° 144Geographic Longitude

168° 160= 152° 144°Geographic Longitude

:ry Weak Glow

. 1 [Diffuse Glow

March 14, 1972 •0846 :06 UT

March 18, 1972 - -0825:06 UT

163C . ?0= 152C 144Geographic Longi tude : .; ? • • ' . Geographic Longitude

Figure 12. Maps of the relationship between the observed positions of the

trapping boundaries for > 130 kev electrons, 50 mHz radar echoes,

and the actual position of visible aurora at 110 km (Romick et al.,

1973).

2030 - 2230 MLT

Invariant LatitudeCutoff Boundary for> 130 KeV Electrons

Invariant LatitudeIsotropic Boundary for > 130 KeV Electrons

76

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0 -10 -20 -30 -40 -50

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Hourly Average DST

Figure 13. Plot of the invariant latitude of the 130 keV trapping boundaries

[cut off (C) and isotropic (I)] versus magnetic indices using data

from magnetic midnight (0^) or local region (QL) and DST and

divided into before (circles) and after (dots) westward traveling

surge activity (Romick et al., 1973).