The recent revival and strong motivation for research in middle atmospheric electrodynamics can be attributed, in large part, to the discovery of large (V/m) electric fields within the lower mesosphere during the decade prior to MAP. Subsequent rocket soundings appeared to verify the preliminary findings. During the MAP era, more sophisticated techniques have been employed to obtain measurements which respond positively to criticisms of earlier results, and which provide more insight regarding the character of the fields. The occurrence of mesospheric V/m electric fields now seems to require the presence of aerosols, of local winds and related dynamics, and of an atmospheric electrical conductivity less than 10(-10)S/m. Furthermore, new theoretical ideas describing the origin of the V/m fields are consistent with the measurements. The current status of results regarding V/m fields in the middle atmosphere is reviewed in light of the more widely accepted electric field structure for this region from rocket, balloon and modeling results

Goldberg, R. A.

English

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178
N89- 29 87 9
6. MIDDLE ATMOSPHERE ELECTRODYNAMICS (MAE)
6.1 MIDDLE ATMOSPHERIC ELECTRODYNAMICS DURING MAP
R. A. Goldberg
NASAX}oddard Space Fright Center
Laboratory for Extraterrestrial Physics
Greenbelt, MD 20771 USA
The recent revival and strong motivation for research in middle atmospheric
electrodynamcis can be attributed, in large part, to the discovery of large (V/m) electric fields
within the lower mesosphere during the decade prior to MAP. Subsequent rocket soundings
appeared to verify the preliminary findings. During the MAP era, more sophisticated
techniques have been employed to obtain measurements which respond positively to criticisms
of earlier results, and which provide more insight regarding the character of the fields. The
occurrence of mesospheric V/m electric fields now seems to require the presence of aerosols,
of local winds and related dynamics, and of an atmospheric electrical conductivity less than
10 -10 S/re. Furthermore, new theoretical ideas describing the origin of the V/m fields are
consistent with the measurements. The current status of results regarding V/m fields in the
middle atmosphere is reviewed in light of the more widely accepted electric field structure for
thisregion from rocket,balloon and modeling results.
WHAT IS MIDDLE ATMOSPHERE ELECTRODYNAMICS ?
* Study of the middle atmospheric electrical environment including :
• Electric fields
• Bulk ion properties
• Charged aerosols
• Free electrons
• Current flow, etc.
• Recent problems under study include :
• Existence and characteristics of large (V/m) E fields.
• A.C. and D.C. E fields related to thunderstorms and lighting.
• E field and plasma perturbations associated with waves and turbulence.
• Modification of MAE parameters by high energy events such as REP's.
Figure I. Middle atmospheric electrodynamics (MAE) is concerned with the study of the
middle atmospheric electricalenvironment including electricfields,bulk ion properties,
charged aerosols,freeelectrons,currentflow,etc.Itisparticularlyconcerned with the manner
in which theseparameters affectmiddle atmospheric coupling with other regions of the near
earth environment and on how the region affectstransmission of electromagnetic waves or
other electricalsignals travelingthrough it. Many of the recent topics receiving attention
through dedicated rocketand balloonprograms are listedin the figureand willbe discussedin
furtherdetailin the fourreview papers which follow. This paper concentrateson theevolution
of our knowledge regarding the apparent large(V/m) electricfieldswhich are occasionally
observed in the lower mesosphere.
https://ntrs.nasa.gov/search.jsp?R=19890020508 2020-03-20T00:41:43+00:00Z
179
H, km
,80
0 LT DATE
/I -- 1 0330. 26 APR 1972
-60 2 0339, 20 0CT1972
0248, 31 MAY 1974x 1345, 21 DEC 1974
-50
40
30 l_
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I I 1 I I l I
-6 -4 -2 0 2 4 6 8
E,V" m"1
Figure 2. Discovery of the vertical Vim fields is attributed to Bragin et al. [1974] and Tyutin
[1976], who reported four rocket measurements of them using field mills abroad the payloads.
The figure displays three night and one day measurements, with the latter occurring at a higher
altitude. The fact that all flights showed existence of the V/m field led the above authors to
conclude that this was a permanent feature of the region, always contained within a region
having a characteristic half width of about 10 km. Bragin, Yu. A., et al., Cosmic Res., 12,
279, 1974; Tyutin, A. A., Cosmic Res., 14, 132, 1976.
180
90
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-2 -1 0 1 2 3 4 5 6 7 8
ANTENNA POTENTIAL (VOLTS)
"'AUROZONE I1""
POKER FLAT, ALASKA:
1 2052 LST, 21 MAR. 1978
"QUIET'"
2 0026 LST, 27 MAR. 1978
"'DISTURBED"
3 0140:30 LST, 29 MAR. 1978
"'REVERSED'"
4 0649 LST. 29 MAR. 1978
"DAY"
OTHER FLIGHTS
8 1050 50 LST, 26 FEB. 1979
CHUKUNI LAUNCH RANGE
6 0600 LST, 27 FEB. 1979
CHUKUNI LAUNCH RANGE
7 0430 LST, 16 SEPT. 1979
WALLOPS ISLAND, VIRGINA
8 1125:25 LST, 16 FEB. 1980
SAN MARCO RANGE, KENYA
9 2030 LST, 16 FEB. 1980
SAN MARCO RANGE, KENYA
Figure 3. Hale et al. [1981] reported results of nine separate rocket flights carry,ing.an
asymmetric probe technique to measure vertical electric fields at several different locauons, but
could only detect Vim fields in two cases. They concluded that the fields were relatively in
frequency, and certainly not a permanent feature of the region. Measurement of a vertical V/m
field was also made by Maynard at Wallops Island, Virginia [Maynard et al., 1981] using a
sophisticated three-dimensional boom-mounted probe array. Hale, L. C., et al., Geophy$.
Res. Lett., 8, 927, 1981; Maynard, N. C., et al., Geophys. Res. Lett, 8, 923, 1981.
181
33.015 33.107
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Figure 4. The first rocket measurements of large (V/m) horizontal electric fields were made on
two separate nights at Andoya, Norway, in 1980 [Maynard ¢t al., 1984]. The field directions
(E) were found to anticorrelate with atmospheric wind directions (W) determined from
simultaneous meteorological rockets. Furthermore, although energetic pardcl¢ events were in
progress during both measurements, the fields were observed to occur below those heights
where significant ionizing radiations had penetrated, which helped contribute to the conclusion
that electrical conductivities above 10--10 S/m would probably not support such fields.
Maynard N. C., ¢t al., ./. Atmos. Terr. Phys., 45, 807, 1984.
8,
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TIME SINCE LIFTOFF (S)
Figure 5. Kelley et al. [1983] also reported detection of an apparent Vim field near 66 kin,
using two sets of boom-mounted probes orthogonal to a rocket payload, each pair of different
length. They found the field measured by the shorter booms to be of higher magnitude than
that measured across the longer separation, leading them to conclude that the measurement was
invalid, probably contaminated by wake effects and other sheath induced charge distributions.
They al,so inferred that all previously reported measurements should be subject to closer
scrutiny to establish their validity. Kelley, M. C., et al., Geophys. Res. Lett., I0, 733, 1983.
182
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Figure 6. In defense of his earlier measurements, Hale [1984] showedtwo independent pairs
of measurements made from Poker Fiat, Alaska, in 1982. On each rocket, Hale measured
vertical electric fields with both an asymmetric double probeand a symmetric boom-mounted
probe technique. On both flights, each approachmeasuredlarge verticalelectric fields between
60 and 70 km of equivalent shape and magnitude, showing consistency between the two
approaches. Later Maynard [1986] showed that an anomolously large electric field would be
measured with his instrument prior to its detachment from the main rocket payload, but that
once separated and in the normal operating mode, measurement values returned to anticipated
levels. This implied that with proper care in design and applications, reliable measurements
should be expected with his technique. Hale, L. C., Adv. Space Res., 4, 175, 1984;
Maynard, N.C., in Rocket Techniques, Handbook for MAP, Vol. 19, 1986.
183
E
Eo
10-1
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Eo = -7.2 V m -1
U = 50ms !
o = 10 -1° S m -1
n+ = 100 cm -3
, I , I I I , ,J==ll
10 -3 10 -2 10 -1 1
m_/m +
Figure 7. More recently, Curtis [1987] has produced a theory which can generate the large
horizontal electric fields given the presence of horizontal winds, of charged aerosols for which
the negative and positive species are of slightly different mass, and of an atmospheric electrical
conductivity which is relatively low (<10 -10 S/m). The plot shows the derived relationship for
changes in the electric field caused by variations in the negatively-to-positively charged aerosol
mass ration, with the displayed values for number density, wind velocity, and conductivity, as
boundary conditions. It is important to note that a very large electric field can be maintained
until the mass ratio becomes very close to unity. If valid, this theory offers encouragement for
the reality of the V/m horizontal electric field measurements. Curtis, S. A., IAGA Abstracts,
CEDAR Symposium, IUGG 19th General Assembly, Vancouver, B.C., August 1987.
184
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I I I I I
.lZ ELECTRIC FIELD (DAUGHTER)
I I I I I
PHOTOMETER #1 (MOTHER)
i i i i i
120,
°°f4O2O
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I I I I I
ALTITUDE
I I I I I
I I I I I
160 180 200 220 240
SECONDS SINCE LAUNCH
140 260
Figure 8. In July 1986, vector electric field measurements were made within a noctilucent
cloud (NLC) [cf. Goldberg, 1987]. The Maynard technique was employed including
deployment of the electric field array (daughter) from the main payload (mother). Displayed
are two components of the electric field measured in the payload coordinate system,
photometer measurements to demonstrate cloud passage [G. Witt, University of Stockholm,
private communication] and altitude. The figure illustrates changes in both components of the
electric field during passage through the NLC. Future measurements of this type in
coordination with simultaneous measurements of winds and particulate size within NL s
should help validate the Curtis theory (Figure 7). Goldberg, R. A., Proceedings of the 8th
ESA Symposium on European Rocket and Balloon Experiments and Related Research, p. 159,
ESA 5,°-270, 1987.
185
WHERE ARE MAE E FIELD STUDIES GOING?
• Further experiments to validate the large (V/m) E fields are needed.
• Tests of the theoretical explanation will be attempted in a noctilucent
cloud environment.
• Expansion of the studies is required to determine the frequency, extent,
and importance of the large (V/m) E fields is required.
Figure 9. Further experiments are needed to validate the large V/m electric fields. If real, they
offer an important mechanism for coupling electrodynamic effects down to tropospheric
altitudes, by generating electrical currents which could significantly contribute to the global
electric circuit. Such contributions would in turn be modulated by incoming radiations during
high latitude disturbances, which would cause conductivity enhancements that might reduce or
eliminate the electric fields altogether. The importance of such effects is dependent on the
frequency and extent of such fields, which must still be determined. Finally, new theoretical
ideas regarding the origin of V.m fields in the mesosphere can be checked through carefully
planned experiments in NLC, which contain all the essential ingredients proposed by the
theory.


Middle Atmosphere Electrodynamics (MAE). Middle atmospheric electrodynamics during MAP

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