The Large-Scale Source Regions of Coronal Mass Ejections

Coronal Mass Ejection is an entire process leading to the ejection of mass and magnetic flux into interplanetary space. Its source is studied by analyzing the associated surface activity. Analysis results show that CMEs have large-scale magnetic source structures, which provide their energy, initiation, and final angular width. This paper review the studies of CME source regions with laying emphasis on their large-scale source structures.

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Large-scale source regions of earth-directed coronal mass ejections

Astronomy and Astrophysics ◽

10.1051/0004-6361:20053536 ◽

2006 ◽

Vol 445 (3) ◽

pp. 1133-1141 ◽

Cited By ~ 44

Author(s):

G. P. Zhou ◽

J. X. Wang ◽

J. Zhang

Keyword(s):

Coronal Mass Ejections ◽

Large Scale ◽

Source Regions

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Source Regions of Coronal Mass Ejections

The Astrophysical Journal ◽

10.1086/323213 ◽

2001 ◽

Vol 561 (1) ◽

pp. 372-395 ◽

Cited By ~ 88

Author(s):

Prasad Subramanian ◽

K. P. Dere

Keyword(s):

Coronal Mass Ejections ◽

Source Regions

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Observations of flux rope formation prior to coronal mass ejections

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313010983 ◽

2013 ◽

Vol 8 (S300) ◽

pp. 209-214 ◽

Cited By ~ 7

Author(s):

Lucie M. Green ◽

Bernhard Kliem

Keyword(s):

Magnetic Flux ◽

Magnetic Structure ◽

Solar Atmosphere ◽

Coronal Mass Ejections ◽

Flux Rope ◽

Active Regions ◽

Magnetic Configuration ◽

Magnetic Flux Rope ◽

Source Regions ◽

Flux Ropes

AbstractUnderstanding the magnetic configuration of the source regions of coronal mass ejections (CMEs) is vital in order to determine the trigger and driver of these events. Observations of four CME productive active regions are presented here, which indicate that the pre-eruption magnetic configuration is that of a magnetic flux rope. The flux ropes are formed in the solar atmosphere by the process known as flux cancellation and are stable for several hours before the eruption. The observations also indicate that the magnetic structure that erupts is not the entire flux rope as initially formed, raising the question of whether the flux rope is able to undergo a partial eruption or whether it undergoes a transition in specific flux rope configuration shortly before the CME.

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Why are CMEs large-scale coronal events: nature or nurture?

Annales Geophysicae ◽

10.5194/angeo-26-3077-2008 ◽

2008 ◽

Vol 26 (10) ◽

pp. 3077-3088 ◽

Cited By ~ 24

Author(s):

L. van Driel-Gesztelyi ◽

G. D. R. Attrill ◽

P. Démoulin ◽

C. H. Mandrini ◽

L. K. Harra

Keyword(s):

Magnetic Reconnection ◽

Large Scale ◽

Observational Evidence ◽

Angular Width ◽

Small Scale ◽

Apparent Contradiction ◽

Lower Corona ◽

Magnetic Structures ◽

Source Regions ◽

Scale Response

Abstract. The apparent contradiction between small-scale source regions of, and large-scale coronal response to, coronal mass ejections (CMEs) has been a long-standing puzzle. For some, CMEs are considered to be inherently large-scale events – eruptions in which a number of flux systems participate in an unspecified manner, while others consider magnetic reconnection in special global topologies to be responsible for the large-scale response of the lower corona to CME events. Some of these ideas may indeed be correct in specific cases. However, what is the key element which makes CMEs large-scale? Observations show that the extent of the coronal disturbance matches the angular width of the CME – an important clue, which does not feature strongly in any of the above suggestions. We review observational evidence for the large-scale nature of CME source regions and find them lacking. Then we compare different ideas regarding how CMEs evolve to become large-scale. The large-scale magnetic topology plays an important role in this process. There is amounting evidence, however, that the key process is magnetic reconnection between the CME and other magnetic structures. We outline a CME evolution model, which is able to account for all the key observational signatures of large-scale CMEs and presents a clear picture how large portions of the Sun become constituents of the CME. In this model reconnection is driven by the expansion of the CME core resulting from an over-pressure relative to the pressure in the CME's surroundings. This implies that the extent of the lower coronal signatures match the final angular width of the CME.

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Strong variability of the Asian Tropopause Aerosol Layer (ATAL) in August 2016 at the Himalayan foothills

10.5194/acp-2020-552 ◽

2020 ◽

Author(s):

Sreeharsha Hanumanthu ◽

Bärbel Vogel ◽

Rolf Müller ◽

Simone Brunamonti ◽

Suvarna Fadnavis ◽

...

Keyword(s):

Boundary Layer ◽

Large Scale ◽

Asian Summer Monsoon ◽

Aerosol Layer ◽

South Asian Summer Monsoon ◽

Air Masses ◽

Source Regions ◽

Himalayan Foothills ◽

Asian Summer ◽

Aerosol Backscatter

Abstract. The South Asian summer monsoon is associated with a large-scale anticyclonic circulation in the Upper Troposphere and Lower Stratosphere (UTLS), which confines the air mass inside. During boreal summer, the confinement of this air mass leads to an accumulation of aerosol between about 13 km and 18 km (360 K and 440 K potential temperature), this accumulation of aerosol constitutes the Asian Tropopause Aerosol Layer (ATAL). We present balloon-borne aerosol backscatter measurements of the ATAL performed by the Compact Optical Backscatter Aerosol Detector (COBALD) instrument in Nainital in Northern India in August 2016, and compare these with COBALD measurements in the post-monsoon time in November 2016. The measurements demonstrate a strong variability of the ATAL's altitude, vertical extent, aerosol backscatter intensity and cirrus cloud occurrence frequency. Such a variability cannot be deduced from climatological means of the ATAL as they are derived from satellite measurements. To explain this observed variability we performed a Lagrangian back-trajectory analysis using the Chemical Lagrangian Model of the Stratosphere (CLaMS). We identify the transport pathways of air parcels contributing to the ATAL over Nainital in August 2016, as well as the source regions of the air masses contributing to the composition of the ATAL. Our analysis reveals a variety of factors contributing to the observed day-to-day variability of the ATAL: continental convection, tropical cyclones (maritime convection), dynamics of the anticyclone and stratospheric intrusions. Thus, the ATAL is a mixture of air masses coming from different atmospheric height layers. In addition, contributions from the model boundary layer originate in different geographic source regions. The location of strongest updraft along the backward trajectories reveal a cluster of strong upward transport at the southern edge of the Himalayan foothills. From the top of the convective outflow level (about 13 km; 360 K) the air parcels ascend slowly to ATAL altitudes within a large-scale upward spiral driven by the diabatic heating in the anticyclonic flow of the South Asian summer monsoon at UTLS altitudes. Cases with a strong ATAL typically show boundary layer contributions from the Tibetan Plateau, the foothills of the Himalayas and other continental regions below the Asian monsoon. Weaker ATAL cases show higher contributions from the maritime boundary layer, often related to tropical cyclones, indicating a mixing of unpolluted and polluted air masses. Because of the strong growth of Asian economies, increasing anthropogenic emissions in the future are expected to enhance the thickness and intensity of the ATAL, thereby also enhancing the global stratospheric aerosol loading, which likely impacts surface climate.

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Combined geometrical modelling and white-light mass determination of coronal mass ejections

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833829 ◽

2019 ◽

Vol 623 ◽

pp. A139 ◽

Cited By ~ 4

Author(s):

Adam Pluta ◽

Niclas Mrotzek ◽

Angelos Vourlidas ◽

Volker Bothmer ◽

Neel Savani

Keyword(s):

Coronal Mass Ejections ◽

Large Scale ◽

Special Focus ◽

Central Meridian ◽

Mass Determination ◽

Geometrical Modelling ◽

Order Of Magnitude ◽

Online Catalogue ◽

Vantage Points

Context. We use forward modelling on multi-viewpoint coronagraph observations to estimate the 3-dimensional morphology, initial speed and deprojected masses of Coronal Mass Ejections (CMEs). The CME structure is described via the Graduated Cylindrical Shell (GCS) model, which enables the measurement of CME parameters in a consistent and comparable manner. Aims. This is the first large-scale use of the GCS model to estimate CME masses, so we discuss inherent peculiarities and implications for the mass determination with a special focus on CME events emerging from close to the observer’s central meridian. Further, we analyse the CME characteristics best suited to estimate the CME mass in a timely manner to make it available to CME arrival predictions. Methods. We apply the method to a set of 122 bright events observed simultaneously from two vantage points with the COR2 coronagraphs onboard of the twin NASA STEREO spacecraft. The events occurred between January 2007 and December 2013 and are compiled in an online catalogue within the EU FP7 project HELCATS. We statistically analyse the derived CME parameters, their mutual connection and their relation to the solar cycle. Results. We show that the derived morphology of intense disk events is still systematically overestimated by up to a factor of 2 with stereoscopic modelling, which is the same order of magnitude as for observations from only one vantage point. The overestimation is very likely a combination of projection effects as well as the increased complexity of separating CME shocks and streamers from CME fronts for such events. We further show that CME mass determination of disk events can lead to overestimation of the mass by about a factor of 10 or more, in case of overlapping bright structures. Conclusions. We conclude that for stereoscopic measurements of disk events, the measurement of the initial CME speed is the most reliable one. We further suggest that our presented CME speed-mass correlation is most suited to estimate the CME mass early from coronagraph observations.

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Climatological perspectives of air transport from atmospheric boundary layer to tropopause layer over Asian monsoon regions during boreal summer inferred from Lagrangian approach

Atmospheric Chemistry and Physics ◽

10.5194/acp-12-5827-2012 ◽

2012 ◽

Vol 12 (13) ◽

pp. 5827-5839 ◽

Cited By ~ 48

Author(s):

B. Chen ◽

X. D. Xu ◽

S. Yang ◽

T. L. Zhao

Keyword(s):

Boundary Layer ◽

Atmospheric Boundary Layer ◽

Large Scale ◽

Transport Model ◽

Asian Summer Monsoon ◽

Indian Subcontinent ◽

Policy Implications ◽

Boreal Summer ◽

The Tibetan Plateau ◽

Source Regions

Abstract. The Asian Summer Monsoon (ASM) region has been recognized as a key region that plays a vital role in troposphere-to-stratosphere transport (TST), which can significant impact the budget of global atmospheric constituents and climate change. However, the details of transport from the boundary layer (BL) to tropopause layer (TL) over these regions, particularly from a climatological perspective, remain an issue of uncertainty. In this study, we present the climatological properties of BL-to-TL transport over the ASM region during boreal summer season (June-July-August) from 2001 to 2009. A comprehensive tracking analysis is conducted based on a large ensemble of TST-trajectories departing from the atmospheric BL and arriving at TL. Driven by the winds fields from NCEP/NCAR Global Forecast System, all the TST-trajectories are selected from the high resolution datasets generated by the Lagrangian particle transport model FLEXPART using a domain-filling technique. Three key atmospheric boundary layer sources for BL-to-TL transport are identified with their contributions: (i) 38% from the region between tropical Western Pacific region and South China Seas (WP) (ii) 21% from Bay of Bengal and South Asian subcontinent (BOB), and (iii) 12% from the Tibetan Plateau, which includes the South Slope of the Himalayas (TIB). Controlled by the different patterns of atmospheric circulation, the air masses originated from these three source regions are transported along the different tracks into the TL. The spatial distributions of three source regions keep similarly from year to year. The timescales of transport from BL to TL by the large-scale ascents r-range from 1 to 7 weeks contributing up to 60–70% of the overall TST, whereas the transport governed by the deep convection overshooting become faster on a timescales of 1–2 days with the contributions of 20–30%. These results provide clear policy implications for the control of very short lived substances, especially for the source regions over Indian subcontinent with increasing populations and developing industries.

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The contribution of X-ray polar blowout jets to the solar wind mass and energy

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313011046 ◽

2013 ◽

Vol 8 (S300) ◽

pp. 239-242 ◽

Cited By ~ 1

Author(s):

Giannina Poletto ◽

Alphonse C. Sterling ◽

Stefano Pucci ◽

Marco Romoli

Keyword(s):

Solar Wind ◽

Kinetic Energy ◽

Energy Budget ◽

Coronal Mass Ejections ◽

Mass Flux ◽

Large Scale ◽

Coronal Holes ◽

Magnetic Loop ◽

Small Scale ◽

X Ray

AbstractBlowout jets constitute about 50% of the total number of X-ray jets observed in polar coronal holes. In these events, the base magnetic loop is supposed to blow open in what is a scaled-down representation of two-ribbon flares that accompany major coronal mass ejections (CMEs): indeed, miniature CMEs resulting from blowout jets have been observed. This raises the question of the possible contribution of this class of events to the solar wind mass and energy flux. Here we make a first crude evaluation of the mass contributed to the wind and of the energy budget of the jets and related miniature CMEs, under the assumption that small-scale events behave as their large-scale analogs. This hypothesis allows us to adopt the same relationship between jets and miniature-CME parameters that have been shown to hold in the larger-scale events, thus inferring the values of the mass and kinetic energy of the miniature CMEs, currently not available from observations. We conclude our work estimating the mass flux and the energy budget of a blowout jet, and giving a crude evaluation of the role possibly played by these events in supplying the mass and energy that feeds the solar wind.

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Correlation slopes of GEM / CO, GEM / CO<sub>2</sub>, and GEM / CH<sub>4</sub> and estimated mercury emissions in China, South Asia, the Indochinese Peninsula, and Central Asia derived from observations in northwestern and southwestern China

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-1013-2015 ◽

2015 ◽

Vol 15 (2) ◽

pp. 1013-1028 ◽

Cited By ~ 22

Author(s):

X. W. Fu ◽

H. Zhang ◽

C.-J. Lin ◽

X. B. Feng ◽

L. X. Zhou ◽

...

Keyword(s):

South Asia ◽

Central Asia ◽

Large Scale ◽

Geometric Mean ◽

Mainland China ◽

Atmospheric Mercury ◽

Southwestern China ◽

Emission Inventories ◽

Mercury Emissions ◽

Source Regions

Abstract. Correlation analyses between atmospheric mercury (Hg) and other trace gases are useful for identification of sources and constraining regional Hg emissions. Emissions of Hg in Asia contribute significantly to the global budget of atmospheric Hg. However, due to the lack of reliable data on the source strength, large uncertainties remain in the emission inventories of Hg in Asia. In the present study, we calculated the correlation slopes of GEM / CO, GEM / CO2, and GEM / CH4 for mainland China, South Asia, the Indochinese Peninsula, and Central Asia using the ground-based observations at three remote sites in northwestern and southwestern China, and applied these values to estimate GEM emissions in the four source regions. The geometric mean GEM / CO correlation slopes for mainland China, South Asia, the Indochinese Peninsula, and Central Asia were 7.3 ± 4.3, 7.8 ± 6.4, 7.8 ± 5.0, and 13.4 ± 9.5 pg m−3 ppb−1, respectively, and values in the same source regions were 33.3 ± 30.4, 27.4 ± 31.0, 23.5 ± 15.3, and 20.5 ± 10.0 pg m−3 ppb−1 for the GEM / CH4 correlation slopes, respectively. The geometric means of GEM / CO2 correlation slopes for mainland China, South Asia, and Central Asia were 240 ± 119, 278 ± 164, 315 ± 289 pg m−3 ppm−1, respectively. These values were the first reported correlation slopes of GEM / CO, GEM / CO2, and GEM / CH4 in four important source regions of Asia, not including the GEM / CO ratios in mainland China. The correlation slopes of GEM / CO, GEM / CO2, and GEM / CH4 in Asia were relatively higher than those observed in Europe, North America, and South Africa, which may highlight GEM emissions from non-ferrous smelting, large-scale and artisanal mercury and gold production, natural sources, and historically deposited mercury (re-emission) in Asia. Using the observed GEM / CO and GEM / CO2 slopes, and the recently reported emission inventories of CO and CO2, the annual GEM emissions in mainland China, South Asia, the Indochinese Peninsula, and Central Asia were estimated to be in the ranges of 1071–1187, 340–470, 125, and 54–90 t, respectively. The estimated quantity of GEM emissions from the GEM / CH4 correlation slopes is significantly larger, which may be due to the larger uncertainties in CH4 emissions in Asia as well as insufficient observations of GEM / CH4 correlation slopes, therefore leading to an overestimate of GEM emissions. Our estimates of GEM emissions in the four Asian regions were significantly higher (3–4 times) than the anthropogenic GEM emissions reported in recent studies. This discrepancy could come from a combination of reasons including underestimates of anthropogenic and natural GEM emissions; large uncertainties related to CO, CO2, and CH4 emission inventories; and inherent limitations of the correlation slope method.

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