Some Characteristics of the Ionospheric Behavior During the Solar Cycle 23 – 24 Minimum

Araujo-Pradere, E. A.; Redmon, R. J.; Fedrizzi, M.; Viereck, R. A.; Fuller‐Rowell, T. J.

doi:10.1007/s11207-011-9728-3

Cited by 53 publications

(56 citation statements)

References 16 publications

(22 reference statements)

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“…Quantitative analysis indicates that solar EUV irradiance, as the primary contributor to the ionization, created a record low ionospheric electron density during the cycle 23/24 minimum. Both the space-borne measurements of EUV irradiance and the proxy 10.7 cm solar radio flux (F10.7 index) in this period were found to be lower than other recent minima, and accordingly the ionospheric critical frequency foF2 and total electron content (TEC) shrank to a record low level (Liu et al, 2011a;Araujo-Pradere et al, 2011).…”

Section: Introductionmentioning

confidence: 72%

Weak ionization of the global ionosphere in solar cycle 24

et al. 2014

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Abstract. Following prolonged and extremely quiet solar activity from 2008 to 2009, the 24th solar cycle started slowly. It has been almost 5 years since then. The measurement of ionospheric critical frequency (foF2) shows the fact that solar activity has been significantly lower in the first half of cycle 24, compared to the average levels of cycles 19 to 23; the data of global average total electron content (TEC) confirm that the global ionosphere around the cycle 24 peak is much more weakly ionized, in contrast to cycle 23. The weak ionization has been more notable since the year 2012, when both the ionosphere and solar activity were expected to be approaching their maximum level. The undersupply of solar extreme ultraviolet (EUV) irradiance somewhat continues after the 2008-2009 minimum, and is considered to be the main cause of the weak ionization. It further implies that the thermosphere and ionosphere in the first solar cycle of this millennium would probably differ from what we have learned from the previous cycles of the space age.

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Section: Introductionmentioning

confidence: 72%

Weak ionization of the global ionosphere in solar cycle 24

et al. 2014

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“…The ionospheric response to the weak CIRs was marginal but observable (Araujo-Pradere et al 2011). However, the weak recurrent geomagnetic activity due to CIRs did produce distinct variability in the thermospheric density at an altitude of 400 km above ground (Lei et al 2011 and references therein).…”

Section: Effect Of the Weak Solar Activitymentioning

confidence: 98%

Short-term variability of the Sun-Earth system: an overview of progress made during the CAWSES-II period

Gopalswamy

Tsurutani

Yan

2015

Prog. in Earth and Planet. Sci.

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This paper presents an overview of results obtained during the CAWSES-II period on the short-term variability of the Sun and how it affects the near-Earth space environment. CAWSES-II was planned to examine the behavior of the solar-terrestrial system as the solar activity climbed to its maximum phase in solar cycle 24. After a deep minimum following cycle 23, the Sun climbed to a very weak maximum in terms of the sunspot number in cycle 24 (MiniMax24), so many of the results presented here refer to this weak activity in comparison with cycle 23. The short-term variability that has immediate consequence to Earth and geospace manifests as solar eruptions from closed-field regions and high-speed streams from coronal holes. Both electromagnetic (flares) and mass emissions (coronal mass ejections -CMEs) are involved in solar eruptions, while coronal holes result in high-speed streams that collide with slow wind forming the so-called corotating interaction regions (CIRs). Fast CMEs affect Earth via leading shocks accelerating energetic particles and creating large geomagnetic storms. CIRs and their trailing high-speed streams (HSSs), on the other hand, are responsible for recurrent small geomagnetic storms and extended days of auroral zone activity, respectively. The latter leads to the acceleration of relativistic magnetospheric 'killer' electrons. One of the major consequences of the weak solar activity is the altered physical state of the heliosphere that has serious implications for the shock-driving and storm-causing properties of CMEs. Finally, a discussion is presented on extreme space weather events prompted by the 23 July 2012 super storm event that occurred on the backside of the Sun. Many of these studies were enabled by the simultaneous availability of remote sensing and in situ observations from multiple vantage points with respect to the Sun-Earth line.

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“…Solomon et al (2010) suggested that this was consistent with the observed EUV irradiance decrease, including a 15% decrease from 1996 to 2009 in the He 304 Å emission observed by the SOHO Solar Extreme-ultraviolet Monitor (SEM). Araujo-Pradere et al (2011) looked at NmF2 and the vertical total electron content (vTEC) at several mid-latitude locations for summer and winter months between 1996 -1997 and 2007 -2009 to see if there was a similar decrease between the WSM solar minimum (1996) and WHI solar minimum. The results were inconclusive for NmF2, but vTEC values did show a decrease of the total electron content in the ionosphere and plasmasphere from the ground to 20 000 km (the altitude of all global positioning satellites) between 1996 and 2008, especially in early evening hours.…”

Section: The Response At Geospacementioning

confidence: 99%

“…Woods et al, 2009;Solomon et al, 2010Solomon et al, , 2011Araujo-Pradere et al, 2011;Emery et al, 2011;Gibson et al, 2011;Haberreiter, 2011;Lei et al, 2011;Wang et al, 2011;White et al, 2011) • Cosmic-ray modulation? Jian, Russell, and Luhmann, 2011) • Morphology of heliosphere?…”

Section: Introductionmentioning

confidence: 99%

“…Lepping et al, 2010;Maris and Maris, 2010;Riley et al, 2011;Webb et al, 2011) • How do they interact with planetary magnetospheres and geospace? (Araujo-Pradere et al, 2011;Emery et al, 2011;Jackman and Arridge, 2011;Lei et al, 2011;Wang et al, 2011) To properly address these questions, the dates of WHI needed to occur near solar minimum, and multi-point heliospheric measurements would have to include out-of-the-Ecliptic observations provided by the Ulysses mission. Fortunately, Ulysses was in an ideal location, and the STEREO mission provided two additional measurements points near the solar Ecliptic plane.…”

Section: Introductionmentioning

confidence: 99%

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A Snapshot of the Sun Near Solar Minimum: The Whole Heliosphere Interval

et al. 2011

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We present an overview of the data and models collected for the Whole Heliosphere Interval, an international campaign to study the three-dimensional solar- heliospheric-planetary connected system near solar minimum. The data and models correspond to solar Carrington Rotation 2068 (20 March -16 April 2008) extending from below the solar photosphere, through interplanetary space, and down to Earth's mesosphere. Nearly 200 people participated in aspects of WHI studies, analyzing and interpreting data from nearly 100 instruments and models in order to elucidate the physics of fundamental heliophysical processes. The solar and inner heliospheric data showed structure consistent with the declining phase of the solar cycle. A closely spaced cluster of low-latitude active regions was responsible for an increased level of magnetic activity, while a highly warped current sheet dominated heliospheric structure. The geospace data revealed an unusually high level of activity, driven primarily by the periodic impingement of high-speed streams. The WHI studies traced the solar activity and structure into the heliosphere and geospace, and provided new insight into the nature of the interconnected heliophysical system near solar minimum.

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Some Characteristics of the Ionospheric Behavior During the Solar Cycle 23 – 24 Minimum

Cited by 53 publications

References 16 publications

Weak ionization of the global ionosphere in solar cycle 24

Weak ionization of the global ionosphere in solar cycle 24

Short-term variability of the Sun-Earth system: an overview of progress made during the CAWSES-II period

A Snapshot of the Sun Near Solar Minimum: The Whole Heliosphere Interval

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