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Solar and Space Physics: A Science for a Technological Society
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SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY
oscillations in the magnetosphere are observed. These occur when the MI system is strongly driven by a
steady solar wind and seem to rely on superfluent nightside outflows of ionospheric O + .
8.3.2 Solar-AIM Coupling
The past decade marked the 23rd solar cycle on modern record. Notable events included a number of
powerful geomagnetic storms, two separate sunspot maxima, and a very deep solar minimum. With observations from an array of space- and ground-based instruments unprecedented in their capabilities, solar
cycle 23 is the first cycle since the initial detection of coronal mass ejections (CMEs) in the early 1970s in
which a complete record of CMEs, coronal hole distributions, and solar wind data are all available over
the whole cycle. The availability of simultaneous space- and ground-based data covering the Sun-Earth
space has made solar cycle 23 solar storms and geomagnetic activity one of the best sets of events to
analyze. It has been possible to assemble atmospheric, ionospheric, magnetospheric, interplanetary, and
solar data on 88 CME storms during solar cycle 23. Many more events of enhanced geomagnetic activity
were observed during this cycle associated with corotating interaction regions (CIRs)/high-speed solar wind
streams (HSS) related to low-heliolatitude distributions of persistent coronal holes.
A few of the CME storms were considered “great” storms that led to unexpected or emergent behavior
in the AIM system. Ionosphere observations indicated the emergence of a daytime super-fountain effect
lifting the ionosphere to new heights and increasing its total electron content by as much as 250 percent.
Also observed were very large amplitude traveling ionospheric disturbances (Figure 8.3), new ionosphere
layers, and very different behavior in equatorial plasma irregularities.
The atmosphere responded with dramatic changes in neutral composition, winds, temperature, and
mass density. Thermosphere mass density at 400 km increased by over 400 percent during these great
storms while experiencing exceptionally fast recovery times, indicating a unique overcooling effect. The
CIR/HSS storms were predominant during the declining and minimum phase of the solar cycle, producing
an entirely different response in the AIM system. Where CME storms lasted a few days and were episodic,
CIR/HSS storms lasted for more than a week and recurred for many solar rotations—in some instances
sustaining common periodicities for an entire year. This has led to the discovery in atmosphere and ionosphere data sets of pervasive periodicities at subharmonics of the ~27-day solar rotation period during solar
cycle 23 (Figure 8.4). Unfortunately, although CHAMP, COSMIC, and ground-based platforms provided
new discoveries in terms of total neutral and plasma density responses of the AIM system to the various
solar disturbances noted above, only sparse measurements were made of the key parameters (e.g., winds,
plasma drifts, neutral and ion composition) needed to understand these responses. It is a high-priority goal
of the next decade to gain this understanding.
8.3.3 Meteorology-AIM Coupling
One of the most exciting developments in recent years has been a new realization of the direct and
strong impact of tropospheric weather and climate on the upper atmosphere and ionosphere. The connection has been elicited, first, from measurements of the ionospheric density near the equator by NASA IMAGE
and TIMED satellites, showing large changes in the structure of the ionosphere on seasonal timescales. This
signature has subsequently been observed in upper-thermospheric composition and temperature. The clear
correspondence demonstrated in this confluence of efforts has energized the study of atmospheric wave
coupling to space plasma. Other observations and model studies have unequivocally revealed that Earth’s
IT system owes a considerable amount of its longitudinal, local time, seasonal-latitudinal, and day-to-day
variability to atmospheric waves that begin near Earth’s surface and propagate into the upper atmosphere.
Solar and Space Physics: A Science for a Technological Society
158
SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY
oscillations in the magnetosphere are observed. These occur when the MI system is strongly driven by a
steady solar wind and seem to rely on superfluent nightside outflows of ionospheric O + .
8.3.2 Solar-AIM Coupling
The past decade marked the 23rd solar cycle on modern record. Notable events included a number of
powerful geomagnetic storms, two separate sunspot maxima, and a very deep solar minimum. With observations from an array of space- and ground-based instruments unprecedented in their capabilities, solar
cycle 23 is the first cycle since the initial detection of coronal mass ejections (CMEs) in the early 1970s in
which a complete record of CMEs, coronal hole distributions, and solar wind data are all available over
the whole cycle. The availability of simultaneous space- and ground-based data covering the Sun-Earth
space has made solar cycle 23 solar storms and geomagnetic activity one of the best sets of events to
analyze. It has been possible to assemble atmospheric, ionospheric, magnetospheric, interplanetary, and
solar data on 88 CME storms during solar cycle 23. Many more events of enhanced geomagnetic activity
were observed during this cycle associated with corotating interaction regions (CIRs)/high-speed solar wind
streams (HSS) related to low-heliolatitude distributions of persistent coronal holes.
A few of the CME storms were considered “great” storms that led to unexpected or emergent behavior
in the AIM system. Ionosphere observations indicated the emergence of a daytime super-fountain effect
lifting the ionosphere to new heights and increasing its total electron content by as much as 250 percent.
Also observed were very large amplitude traveling ionospheric disturbances (Figure 8.3), new ionosphere
layers, and very different behavior in equatorial plasma irregularities.
The atmosphere responded with dramatic changes in neutral composition, winds, temperature, and
mass density. Thermosphere mass density at 400 km increased by over 400 percent during these great
storms while experiencing exceptionally fast recovery times, indicating a unique overcooling effect. The
CIR/HSS storms were predominant during the declining and minimum phase of the solar cycle, producing
an entirely different response in the AIM system. Where CME storms lasted a few days and were episodic,
CIR/HSS storms lasted for more than a week and recurred for many solar rotations—in some instances
sustaining common periodicities for an entire year. This has led to the discovery in atmosphere and ionosphere data sets of pervasive periodicities at subharmonics of the ~27-day solar rotation period during solar
cycle 23 (Figure 8.4). Unfortunately, although CHAMP, COSMIC, and ground-based platforms provided
new discoveries in terms of total neutral and plasma density responses of the AIM system to the various
solar disturbances noted above, only sparse measurements were made of the key parameters (e.g., winds,
plasma drifts, neutral and ion composition) needed to understand these responses. It is a high-priority goal
of the next decade to gain this understanding.
8.3.3 Meteorology-AIM Coupling
One of the most exciting developments in recent years has been a new realization of the direct and
strong impact of tropospheric weather and climate on the upper atmosphere and ionosphere. The connection has been elicited, first, from measurements of the ionospheric density near the equator by NASA IMAGE
and TIMED satellites, showing large changes in the structure of the ionosphere on seasonal timescales. This
signature has subsequently been observed in upper-thermospheric composition and temperature. The clear
correspondence demonstrated in this confluence of efforts has energized the study of atmospheric wave
coupling to space plasma. Other observations and model studies have unequivocally revealed that Earth’s
IT system owes a considerable amount of its longitudinal, local time, seasonal-latitudinal, and day-to-day
variability to atmospheric waves that begin near Earth’s surface and propagate into the upper atmosphere.