Monitoring of earth's atmosphere was conducted for several years utilizing the ITOS series of low-altitude, polar-orbiting weather satellites. A space environment monitoring package was included in these satellites to perform measurements of a portion of earth's charged particle environment. The charged particle observations proposed for the low-altitude weather satellite TIROS N, are described which will provide the capability of routine monitoring of the instantaneous total energy deposition into the upper atmosphere by the precipitation of charged particles from higher altitudes. Such observations may be of use in future studies of the relationships between geomagnetic activity and atmospheric weather pattern developments. Estimates are given to assess the potential importance of this type of energy deposition. Discussion and examples are presented illustrating the importance of distinguishing between solar and geomagnetic activity as possible causative sources. Such differentiation is necessary because of the widely different spatial and time scales involved in the atmospheric energy input resulting from these various sources of activity

Evans, D. S.

Grubb, R. N.

Sauer, H. H.

Williams, D. J.

English

NASA Technical Reports Server

1
 N76 14544
Future Monitoring of Charged Particle Energy
Deposition Into the Upper Atmosphere and
Comments on Possible Relationships Between
Atmospheric Phenomena and Solar and /or
Geomagnetic Activity
D. J. WILLIAMS, R. N. GRUBB, D. S. EVANS, AND H. H. SAUER
National Oceanic and Atmospheric Administration
The Na.tional Oceanic and Atmospheric Administration has been performing routine
monitoring of Earth's atmosphere for several years utilizing the ITOS series of low-altitude,
polar-orbiting weather satellites. A space environment monitoring package has been included
in these satellites to perform measurements of a portion of Earth's charged particle environ-
ment. We describe briefly the charged particle observations proposed for the new low-altitude
weather satellite TIROS N, which will provide the capability of routine monitoring of the
instantaneous total energy deposition into the upper atmosphere by the precipitation of charged
particles from higher altitudes. Such observations may be of use in future studies of the rela-
tionships between geomagnetic activity and atmospheric weather pattern developments. Esti-
mates are given to assess the potential importance of this type of energy deposition. Discussion
and examples are presented illustrating the importance of distinguishing between solar and
geomagnetic activity as possible causative sources. Such differentiation is necessary because of
the widely different spatial and time scales involved in the atmospheric energy input resulting
from these various sources of activity. Examples also are given illustrating the importance of
thoroughly investigating all physical mechanisms that may potentially link the lower atmos-
phere to the varying energy inputs at high altitudes.
I am happy to have this opportunity to describe
and comment briefly on the type and usefulness
of charged particle measurements to be performed
on the proposed TIROS N environmental satellite
program. These measurements, concerning the
energy deposition in the upper atmosphere due to
charged particles, should be of use in future con-
siderations of atmospheric weather phenomena
and their relationship to solar and/or geomag-
netic activity. It should be noted that the TIROS
N environmental satellite program has not yet
been approved and is presently under review by
the Office of Management and Budget.
Figure 1 is a schematic showing the orbit of
the TIROS N spacecraft. The proposed orbit
is circular at an altitude of 1700 km with a
103° inclination, which maintains it in a Sun-
synchronous attitude. A currently operating real-
time data transmission system is illustrated in the
figure. Data are available at the Space Environ-
ment Laboratory in near real -time and are imme-
diately placed into an operational real-time data
base made up of data collected throughout the
solar/terrestrial environment. In addition, the
satellite data recorded throughout the orbit are
available on a longer time basis for research and
archiving.
The satellite is oriented at high latitudes so
that the charged-particle detectors are able to
obtain a measure of the particle pitch angle distri-
155
https://ntrs.nasa.gov/search.jsp?R=19760007456 2020-03-22T18:21:11+00:00Z
156 RELATIONSHIPS BETWEEN SOLAR ACTIVITY AND METEOROLOGICAL PHENOMENA
Orbit 1700 km
Circular 103°
Sun Synchronous
FIGURE 1.—TIROS N spacecraft orbit. It will be launched
in mid 1977. Followup operational spacecraft, will be
launched at 1- to 2-yr intervals. (NESS = National
Environmental Satellite Service; SEL = Space En-'
vironment Laboratory.)
bution at these altitudes. A set of detectors looks
normal to the field line, thereby measuring parti-
cles with a local pitch angle of 90°. An additional
set of detectors is oriented to look upward nearly
along the field line, thereby measuring particles
whose local pitch angles are very small. It is these
latter particles that precipitate directly into the
upper atmosphere and are directly responsible for
such phenomena as polar cap absorption, auroral
displays, and possibly phenomena in the lower
atmosphere. The charged-particle observations
aboard TIROS N therefore allow the measure-
ment of the total instantaneous energy deposition
to the local atmosphere due to charged particles.
Figure 2 shows the energy range to be covered.
This range extends from several hundred to
greater than 109 eV. A variety of detectors (thin
scintillators, solid-state detectors, and Cerenkov
detectors) will be used to cover this energy range
and will be sized to measure energy inputs greater
than or equal to 10'2 ergs/cm2 . s. Details of how
the various energy ranges will be covered and
details of instrument design can be obtained from
the Space Environment Laboratory, Boulder,
Colo.
Because we are proposing to monitor on a rou-
tine basis the energy deposition at the top of the
atmosphere due to charged particles, let us try to
assess its importance. In figure 3, we show a
photograph of an aurora obtained from the DOD
Data Acquisition and Processing Program (DAPP)
satellite on January 11, 1973. Included in the
figure is a summary of estimates of energy depos-
ited by such an aurora into the upper atmosphere.
The upper portion of the auroral photograph is
in the dawn hemisphere, the broad diffused band
near the right-hand portion is near local midnight,
and the two line structures extending to the lower
left of the photograph are in the local, evening
sector. The aurora also can be seen over the polar
cap alined in the noon-midnight direction.
The area of the photograph is approximately
1.4 X 107 km2, with approximately 20 percent of
the area covered with auroral glow. A modest
energy influx during an aurora is approximately
4 ergs/cm2 • s. This value yields a total energy
influx in figure 3 of approximately 10" ergs/s =
10l° W.
We also can estimate the total power dissipa-
tion through joule heating due to ionospheric cur-
rent flow at the 115-km level. Using an iono-
spheric integrated Pederson conductivity for
moderate levels of disturbance of
2a ~ 20 mhos/m
and a nominal potential difference of about 0.015
V/m, a power dissipation of approximately 4.5 X
10"3 W is obtained for a column of 1, m2 cross
section. If this current is flowing within the auro-
ral glow shown in figure 3, a total power dissipa-
tion of approximately 1010 W exists.
Using these estimates, considering the possibil-
ity of current along geomagnetic field lines, and
estimating the volume energy deposition rates due
to auroral particle precipitation, heating rates, of
more than 1000 K per day (1.4 X \Qr- K/s)
result if the assumption is made that this energy
heats the neutral atmosphere at these altitudes
(110 to 125 km). Thus it is apparent from such
estimates that the energy deposition into the
atmosphere at altitudes above 110 km due to
magnetospheric processes exceeds that due to
solar energy flux at high' geomagnetic latitudes.
This should not only cause considerable heating
of the high-altitude neutral atmosphere but may
also generate significant neutral winds at these
altitudes.
The preceding estimates were concerned with
intense particle precipitation due primarily to geo-
magnetic processes. Let us consider an example
of such effects ,due to solar flare activity. In con-
CHARGED PARTICLE ENERGY DEPOSITION INTO' THE UPPER ATMOSPHERE 157
Total Energy Detector
Low Energy
Proton Alpha Telescope
Medium Energy Detectors
( Integral Channels)
High Energy Telescope
(Integral Channels )
Protons i
150 300 600 1.4 66 40
600 1.35 3
Alphas bt
100
140
800
Electrons
Protons
400
600h
Alphas
lOOOt-
600
I c
lOOOh
1 KeV 10 10 100100 1 MeV
Particle Energy
FIGURE 2.—Energy coverage of proposed TIROS N space environment monitor.
1000
trast with auroral particle precipitation, which is
confined to a relatively narrow latitude band
(^10°) and may last for hours, particles released
from a solar flare impinge on Earth's atmosphere
over the entire polar cap region and last for sev-
eral days. Thus the time scales for the energy
input are longer and the atmospheric spatial scales
over which the energy input occurs are greater
for solar flare particles than for auroral processes.
In contrast, however, the frequency of occurrence
is greater for auroras than it is for particle-
emitting solar flares.
We shall use the solar flare activity occurring
in August 1972 to obtain an estimate of energy
dissipation into the upper atmosphere over one
polar cap. For the several days during which
intense solar particle activity occurred during the
August 1972 solar exents, a peak energy dissipa-
tion rate into the polar cap of approximately
2 ergs/cm2 • s occrured for a Vfz-hr period. For
the remaining several days of this solar activity,
the energy dissipation rate due to flare-associated
particles was less than approximately 0.2 ergs/
cm2 • s. Using a polar cap area of approximately
2.5 X 1017 cm2 yields a peak energy dissipation
rate over one polar cap of 5 X 1017 ergs/s =
5 X 1010 W. Using the Vi-hr time interval for the
event peak yields a total peak power of 3 X 107
kW hours deposited in an altitude range of 40 to
70 km. This could give a mean heating of the
order of 1° to 3° over the altitude range of
deposition.
We see evidence for significant energy deposi-
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FIGURE 3.—Aurora obtained from the Data Acquisition
and Processing Program (DAPP) satellite on January
11, 1973. The estimated area of the aurora in the
satellite picture is approximately 2.8 X 10" km2. For a
commonly occurring "moderate" aurora, which will
last for several hours, the particle energy deposition is
approximately 4.0 ergs/cm1 . s, or a total power input
of approximately I.I X 1010 W. The ohmic losses due
to the Pedersen currents flowing at 110 to 120 km
may be approximately 1 x io10 W. If these processes
heat the neutral atmosphere at 115 km, the resultant
heating rate would be greater than 1000 K/day.
158 RELATIONSHIPS BETWEEN SOLAR ACTIVITY AND METEOROLOGICAL PHENOMENA
tion in Earth's upper atmosphere due, in this
case, to, particles emitted during a solar flare.
Consequently, the routine observations of such
energy depositions may play an important role in
delineating mechanisms responsible for correla-
tions between atmospheric weather and solar
and/or geomagnetic activity.
In such correlations, it is extremely important
to distinguish between solar activity and geomag-
netic activity because of the vast differences in
the spatial and temporal scales of the energy input
into Earth's, upper atmosphere. At this conference
we are hearing of potential atmospheric responses
ranging in time from several days (corresponding
to the development of atmospheric storm systems)
to 11 to 22 yr (corresponding to correlations with
the solar.cycle) and on to many millenia (corre-
sponding to hypotheses concerned with glacial
advances and recessions). Similarly, the spatial
scales in the atmosphere vary from more or less
localized continental storm systems to global cli-
matic changes.
If causes related to variations in the solar ter-
restrial realm are sought, it is important that the
necessary energy input be compatible with the
atmospheric phenomena being studied. For exam-
ple, any variation in the electromagnetic emission
of the Sun (X-ray, UV, visible, IR, and radio
energy) produces a global variation throughout
Earth's sunlit hemisphere. Consequently, slight
TABLE 1.—Spatial and Temporal Considerations of Energy Inputs to Atmosphere Associated With Solar
and Geomagnetic Activity
Extra-atmospheric activity Time
scale
Atmospheric
spatial scale"
Solar: Millennia(?) Global, direct
Overall change in electromag-
netic emission from the Sun
(includes possible changes in
solar constant)
Overall change in emitted solar Millennia(?) Global, indirect
wind
Number of sunspots*
Solar flare particle emission
Solar flare shock wave
Solar cycle Global, direct, indirect
11 to 22
yr
Days Polar regions, direct
Hours Global, indirect
Potential atmospheric effects
Long-term worldwide climatic changes.
Glacial advances and recessions.
Long-term worldwide climatic changes.
Glacial advances and recessions.
Shorter term climatic changes, for
example, the 20- to 22-yr cycle of
U.S. High Plains droughts. Motion
of atmospheric jet stream.
Atmospheric storm system develop-
ment. Isolated, unique atmospheric
phenomena.
Atmospheric storm system develop-
ment. Isolated, unique atmospheric
phenomena.
Geomagnetic: Hours
Aurora (precipitated particles and
currents in substorms)
Magnetic storms Days
Narrow latitude band Atmospheric storm system develop-
(^10°) at high latitudes. ment. Isolated, unique atmospheric
Night side. Direct. phenomena.
Wide latitude band at mid- Atmospheric storm system develop-
latitudes. Global. Direct. ment. Isolated, unique atmospheric
phenomena.
' Direct = energy from given phenomena applied directly to the 'atmosphere. Indirect = energy from given phe-
nomena applied indirectly to the atmosphere; for example, solar wind energy applied through magnetospheric coupling
to the atmosphere.
b
 As indication of overall solar activity.
CHARGED PARTICLE ENERGY DEPOSITION INTO THE UPPER ATMOSPHERE 159
changes in the solar constant over long periods of
time might provide a more appropriate mechanism
to explain long-term global climatic variations.
Table 1 is a rough attempt to block out atmos-
pheric spatial and temporal scale sizes associated
with a few examples of solar and geomagnetic
activity. It is not intended to imply cause and
effect but simply to emphasize the spatial and
temporal scales of atmospheric energy input asso-
ciated with various types of solar and geomag-
netic activity.
Finally, in attempting to understand many of
the correlations being presented, it is necessary
to examine all possible mechanisms that may con-
ceivably provide a connection between the lower
atmosphere (^10 km) and solar and geomag-
netic activity. For example, it has been long
known that atmospheric turbulence is capable of
producing upward-traveling acoustic gravity waves
that can carry significant amounts of energy into
the high altitude (^100 km) regions. If this
occurs under conditions of marginal stability in
the geomagnetic particle population, these waves
could conceivably create turbulence in the iono-
sphere at the foot of the geomagnetic field lines
and initiate instabilities leading to enhanced parti-
cle precipitation. Note that such possibilities are
maximized when enhanced geomagnetic activity
is imminent and when large atmospheric storm
systems are developing, and would naturally lead
to positive correlations under conditions set forth
in many reported studies. Ionospheric effects of
this type apparently have been observed (Bauer,
1957, 1958; Davies and Jones, 1971, 1973) and,
in one case, interpreted as upward/propagating
acoustic gravity waves setting the ionosphere at
200-km altitude into large-scale vertical oscilla-
tions having periods of several minutes (Davies
and Jones, 1973). Mechanisms such as this should
be identified, assessed in importance, and clearly
separated in correlations of atmospheric weather
development with solar and/or geomagnetic activ-
ity. Only then will the reality of solar activity and
geomagnetic effects on Earth's weather and cli-
mate be established.
ACKNOWLEDGMENTS
We would like to acknowledge the U.S. Air
Force, Air Weather Service, and the World Data
Center A, National Oceanic and Atmospheric
Administration, Boulder, Colo., for providing the
DAPP satellite photo in figure 3.
REFERENCES
Bauer, S. J., 1957, "A Possible Troposphere-Ionosphere
Relationship," J. Geophys. Res., 62, p. 425.
Bauer, S. J., 1958, "An Apparent Ionospheric Response
to the Passage of Hurricanes," J. Geophys. Res., 63,
p. 265.
Davies, K., and John E. Jones, 1971, "Ionospheric Dis-
turbances in the F2-Region Associated With Severe
Thunderstorms," J. Almos. Sci., 28, (2), pp. 254-262.
Davies, K., and J. E. Jones, 1973, "Acoustic Waves in
the Ionospheric F2-Region Produced by Severe Thun-
derstorms," J. Atmospher. Terr. Phys., 35, pp. 1737-
1744.


Future monitoring of charged particle energy deposition into the upper atmosphere and comments on possible relationships between atmospheric phenomena and solar and/or geomagnetic activity

Future monitoring of charged particle energy deposition into the upper atmosphere and comments on possible relationships between atmospheric phenomena and solar and/or geomagnetic activity

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