The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Brian A. Tinsley - One of the best experts on this subject based on the ideXlab platform.
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solar wind Atmospheric Electricity cloud microphysics connections to weather and climate
Journal of Atmospheric and Solar-Terrestrial Physics, 2016Co-Authors: Mai Mai Lam, Brian A. TinsleyAbstract:Abstract We review recent research articles that present observations of the large-scale day-to-day dynamic tropospheric response to changes in the downward current density Jz of the global Atmospheric electric circuit (GEC). The evidence for the global circuit downward current density, Jz, causing changes in Atmospheric dynamics is now even stronger than as reviewed by Tinsley (2008) (Rep. Prog. Phys. 71, 066801). We consider proposed mechanisms for these responses, and suggest future directions for research.
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Atmospheric transparency changes associated with solar wind induced Atmospheric Electricity variations
Journal of Atmospheric and Solar-Terrestrial Physics, 2004Co-Authors: V C Roldugin, Brian A. TinsleyAbstract:Abstract Variations in Atmospheric transmission of several percent in nominally clear air are found to accompany solar wind events associated with variations on the day-to-day timescale in the flow of vertical current density (Jz) in the global electric circuit. The effect has been observed only for stations at high latitudes (>55°N). Increases in transmission are present when inferred Jz decreases occurred without changes in tropospheric ion production. These events occurred when there was a high loading of stratospheric aerosols. Responses of opposite sign, i.e., decreases in transmission, are present when Forbush decreases of galactic cosmic ray flux occur, but only during periods of low stratospheric aerosol loading. Forbush decreases are associated with both tropospheric ion production decreases and Jz decreases. Similar effects are present on the 11-year solar cycle, with climate consequences that have yet to be analyzed. The mechanisms for these phenomena are not understood, but the nature of the observations suggests that explanations should be sought in terms of theories of the effects of electric charge on the formation of aerosols, and/or effects of charged aerosols on the microphysics of vapor–water–ice conversions.
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do effects of global Atmospheric Electricity on clouds cause climate changes
Eos Transactions American Geophysical Union, 1997Co-Authors: Brian A. TinsleyAbstract:In recent years increasing numbers of papers have been published and presented at meetings (at least 20 at the 1996 Fall AGU meeting) reporting correlations between climate and solar variations. The statistical confidence for the correlations is so high that there is now little reason to question that there is a physical link; the main puzzle now is the nature of the mechanisms involved. The mechanisms have been sought for the past two centuries, and during this time some pieces of the puzzle have been uncovered. They can now be fitted together to suggest a fascinating picture.
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are stratospheric aerosols the missing link between tropospheric vorticity and earth transits of the heliospheric current sheet
Journal of Geophysical Research, 1996Co-Authors: Matt W Kirkland, Brian A. Tinsley, Todd J HoeksemaAbstract:Evidence has accumulated for the past two decades demonstrating a correlation between Earth transits of the heliospheric current sheet (HCS) and changes in winter tropospheric vorticity. These correlations persisted for a few years following the Agung and El Chichon volcanic eruptions, but were significantly weaker at other times. This suggests that the missing link in a physical mechanism explaining the correlation may involve volcanic aerosols and their effect on cloud microphysics, via Atmospheric Electricity. An analysis of 500-mbar northern hemispheric vorticity for the 1991-1994 winter periods following the Pinatubo eruption shows a similar correlation between tropospheric vorticity and Earth transits of the HCS, supporting the previous interpretation.
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stratospheric volcanic aerosols and changes in air earth current density at solar wind magnetic sector boundaries as conditions for the wilcox tropospheric vorticity effect
Journal of Geophysical Research, 1994Co-Authors: Brian A. Tinsley, Todd J Hoeksema, Daniel N. BakerAbstract:A correlation between tropospheric dynamics and solar wind magnetic fields that disappeared in the early 1970s reappeared with a new injection of volcanic aerosols into the stratosphere. A similar pattern of correlation has been found for changes in current density in the global electric circuit and for changes in relativistic electron precipitation. Several other weather and climate variations have been found to correlate with changes in air-earth current density due to solar wind modulation of the global electric circuit. The accumulation of electrostatic charge on supercooled droplets at cloud tops responds to air-earth current density changes. A mechanism linking the effects of charge accumulation to changes in ice nucleation, precipitation efficiency, latent heat retention and perturbations in Atmospheric dynamics is thus as an explanation for this and other solar wind - Atmospheric Electricity - weather and climate correlations.
R.g. Harrison - One of the best experts on this subject based on the ideXlab platform.
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a global Atmospheric Electricity monitoring network for climate and geophysical research
Journal of Atmospheric and Solar-Terrestrial Physics, 2019Co-Authors: Veronika Barta, R.g. Harrison, Keri Nicoll, Jozsef Bor, R Brugge, A Chillingarian, Jaroslav Chum, A K Georgoulias, Anirban GuhaAbstract:Abstract The Global Atmospheric Electric Circuit (GEC) is a fundamental coupling network of the climate system connecting electrically disturbed weather regions with fair weather regions across the planet. The GEC sustains the fair weather electric field (or potential gradient, PG) which is present globally and can be measured routinely at the surface using durable instrumentation such as modern electric field mills, which are now widely deployed internationally. In contrast to lightning or magnetic fields, fair weather PG cannot be measured remotely. Despite the existence of many PG datasets (both contemporary and historical), few attempts have been made to coordinate and integrate these fragmented surface measurements within a global framework. Such a synthesis is important in order to fully study major influences on the GEC such as climate variations and space weather effects, as well as more local Atmospheric electrical processes such as cloud electrification, lightning initiation, and dust and aerosol charging. The GloCAEM (Global Coordination of Atmospheric Electricity Measurements) project has brought together experts in Atmospheric Electricity to make the first steps towards an effective global network for Atmospheric Electricity monitoring, which will provide data in near real time. Data from all sites are available in identically-formatted files, at both 1 s and 1 min temporal resolution, along with meteorological data (wherever available) for ease of interpretation of electrical measurements. This work describes the details of the GloCAEM database and presents what is likely to be the largest single analysis of PG data performed from multiple datasets at geographically distinct locations. Analysis of the diurnal variation in PG from all 17 GloCAEM sites demonstrates that the majority of sites show two daily maxima, characteristic of local influences on the PG, such as the sunrise effect. Data analysis methods to minimise such effects are presented and recommendations provided on the most suitable GloCAEM sites for the study of various scientific phenomena. The use of the dataset for further understanding of the GEC is also demonstrated, in particular for more detailed characterization of day-to-day global circuit variability. Such coordinated effort enables deeper insight into PG phenomenology which goes beyond single-location PG measurements, providing a simple measurement of global thunderstorm variability on a day-to-day timescale. The creation of the GloCAEM database is likely to enable much more effective study of Atmospheric Electricity variables than has ever been possible before, which will improve our understanding of the role of Atmospheric Electricity in the complex processes underlying weather and climate.
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saharan dust electrification perceived by a triangle of Atmospheric Electricity stations in southern portugal
Journal of Electrostatics, 2016Co-Authors: H G Silva, R.g. Harrison, Keri Nicoll, Susana Barbosa, Francis M Lopes, Sergio Pereira, Ricardo Conceicao, S Neves, Collares M PereiraAbstract:Abstract Atmospheric Electric Potential Gradient (PG) measurements were carried out in three sites forming a triangular array in Southern Portugal. The campaign was performed during the summer, characterized by Saharan dust outbreaks; 16th–17th July 2014 dust event is considered. Short time-scale oscillations of the PG at two of the stations and a mid time-scale suppression of the PG in the three stations are found. Results are interpreted as evidencing long-range dust electrification; attributed to the air-Earth electrical current creating a bipolar charge distribution inside of the dust layer. The relevance of using arrays of sensors, instead of single sited, is highlighted.
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lord kelvin s Atmospheric Electricity measurements
History of Geo- and Space Sciences, 2013Co-Authors: K L Aplin, R.g. HarrisonAbstract:Abstract. Lord Kelvin (William Thomson) made important contributions to the study of Atmospheric Electricity during a brief but productive period from 1859–1861. By 1859 Kelvin had recognised the need for "incessant recording" of Atmospheric electrical parameters, and responded by inventing both the water dropper equaliser for measuring the Atmospheric potential gradient (PG), and photographic data logging. The water dropper equaliser was widely adopted internationally and is still in use today. Following theoretical considerations of electric field distortion by local topography, Kelvin developed a portable electrometer, using it to investigate the PG on the Scottish island of Arran. During these environmental measurements, Kelvin may have unwittingly detected Atmospheric PG changes during solar activity in August/September 1859 associated with the "Carrington event", which is interesting in the context of his later statements that solar magnetic influence on the Earth was impossible. Kelvin's Atmospheric Electricity work presents an early representative study in quantitative environmental physics, through the application of mathematical principles to an environmental problem, the design and construction of bespoke instrumentation for real world measurements and recognising the limitations of the original theoretical view revealed by experimental work.
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lord kelvin s Atmospheric Electricity measurements
arXiv: History and Philosophy of Physics, 2013Co-Authors: K L Aplin, R.g. HarrisonAbstract:Lord Kelvin (William Thomson) made important contributions to the study of Atmospheric Electricity during a brief but productive period from 1859-1861. By 1859 Kelvin had recognised the need for "incessant recording" of Atmospheric electrical parameters, and responded by inventing both the water-dropper instrument for measuring the Atmospheric Potential Gradient (PG), and photographic data logging. The water-dropper was widely adopted internationally and is still in use today. Following theoretical considerations of electric field distortion by local topography, Kelvin developed a portable electrometer, using it to investigate PG on the Scottish island of Arran. During these environmental measurements, Kelvin may have unwittingly detected Atmospheric PG changes during solar activity in August/September 1859 associated with the "Carrington event". Kelvin's Atmospheric Electricity work presents an early representative study in quantitative environmental physics, through the application of mathematical principles to an environmental problem, the design and construction of bespoke instrumentation for real world measurements and the limitations of the original theoretical view revealed by experimental work.
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aerosol induced correlation between visibility and Atmospheric Electricity
Journal of Aerosol Science, 2012Co-Authors: R.g. HarrisonAbstract:Abstract Atmospheric aerosol acts both to reduce the background concentration of natural cluster ions, and to attenuate optical propagation. Hence, the presence of aerosol has two consequences, the reduction of the air's electrical conductivity and the visual range. Ion-aerosol theory and Koschmieder's visibility theory are combined here to derive the associated non-linear variation of the Atmospheric electric potential gradient with visual range. A substantial sensitivity is found under poor visual range conditions, but, for good visual range conditions the sensitivity diminishes and little influence of local aerosol on the fair weather potential gradient occurs. This allows visual range measurements, made simply and routinely at many meteorological sites, to provide inference about the local air's electrical properties.
Todd J Hoeksema - One of the best experts on this subject based on the ideXlab platform.
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are stratospheric aerosols the missing link between tropospheric vorticity and earth transits of the heliospheric current sheet
Journal of Geophysical Research, 1996Co-Authors: Matt W Kirkland, Brian A. Tinsley, Todd J HoeksemaAbstract:Evidence has accumulated for the past two decades demonstrating a correlation between Earth transits of the heliospheric current sheet (HCS) and changes in winter tropospheric vorticity. These correlations persisted for a few years following the Agung and El Chichon volcanic eruptions, but were significantly weaker at other times. This suggests that the missing link in a physical mechanism explaining the correlation may involve volcanic aerosols and their effect on cloud microphysics, via Atmospheric Electricity. An analysis of 500-mbar northern hemispheric vorticity for the 1991-1994 winter periods following the Pinatubo eruption shows a similar correlation between tropospheric vorticity and Earth transits of the HCS, supporting the previous interpretation.
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stratospheric volcanic aerosols and changes in air earth current density at solar wind magnetic sector boundaries as conditions for the wilcox tropospheric vorticity effect
Journal of Geophysical Research, 1994Co-Authors: Brian A. Tinsley, Todd J Hoeksema, Daniel N. BakerAbstract:A correlation between tropospheric dynamics and solar wind magnetic fields that disappeared in the early 1970s reappeared with a new injection of volcanic aerosols into the stratosphere. A similar pattern of correlation has been found for changes in current density in the global electric circuit and for changes in relativistic electron precipitation. Several other weather and climate variations have been found to correlate with changes in air-earth current density due to solar wind modulation of the global electric circuit. The accumulation of electrostatic charge on supercooled droplets at cloud tops responds to air-earth current density changes. A mechanism linking the effects of charge accumulation to changes in ice nucleation, precipitation efficiency, latent heat retention and perturbations in Atmospheric dynamics is thus as an explanation for this and other solar wind - Atmospheric Electricity - weather and climate correlations.
A J Bennett - One of the best experts on this subject based on the ideXlab platform.
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effects of the march 2015 solar eclipse on near surface Atmospheric Electricity
Philosophical Transactions of the Royal Society A, 2016Co-Authors: A J BennettAbstract:Measurements of Atmospheric electrical and standard meteorological parameters were made at coastal and inland sites in southern England during the 20 March 2015 partial solar eclipse. Clear evidence of a reduction in air temperature resulting from the eclipse was found at both locations, despite one of them being overcast during the entire eclipse. The reduction in temperature was expected to affect the near-surface electric field (potential gradient (PG)) through a reduction in turbulent transfer of space charge. No such effect could be unambiguously confirmed, however, with variability in PG and air-Earth current during the eclipse being comparable to pre- and post-eclipse conditions. The already low solar radiation for this latitude, season and time of day was likely to have contributed to the reduced effect of the eclipse on Atmospheric Electricity through boundary layer stability. The absence of a reduction in mean PG shortly after time of maximum solar obscuration, as observed during eclipses at lower geomagnetic latitude, implied that there was no significant change in Atmospheric ionization from cosmic rays above background variability. This finding was suggested to be due to the relative importance of cosmic rays of solar and galactic origin at geomagnetic mid-latitudes.This article is part of the themed issue 'Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse'.
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Multi-station synthesis of early twentieth century surface Atmospheric Electricity measurements for upper tropospheric properties
Advances in Geosciences, 2007Co-Authors: R.g. Harrison, A J BennettAbstract:The vertical columnar current density in the global Atmospheric electrical circuit depends on the local columnar resistance. A simple model for the columnar resistance is suggested, which separates the local boundary layer component from the upper troposphere cosmic ray component, and calculates the boundary layer component from a surface measurement of air conductivity. This theory is shown to provide reasonable agreement with observations. One application of the simple columnar model theory is to provide a basis for the synthesis of surface Atmospheric electrical measurements made simultaneously at several European sites. Assuming the ionospheric potential to be common above all the sites, the theoretical air-earth current density present in the absence of a boundary layer columnar resistance can be found by extrapolation. This is denoted the free troposphere limit air-earth current density, J0. Using early surface data from 1909 when no ionospheric potential data are available for corroboration, J0 is found to be ~6 pA m?2, although this is subject to uncertainties in the data and limitations in the theory. Later (1966?1971) European balloon and surface data give J0=2.4 pA m?2.
F J Gordillovazquez - One of the best experts on this subject based on the ideXlab platform.
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analysis of the spatial nonuniformity of the electric field in spectroscopic diagnostic methods of Atmospheric Electricity phenomena
Journal of Geophysical Research, 2019Co-Authors: A Malagonromero, Alejandro Luque, F J Perezinvernon, F J GordillovazquezAbstract:The spatial nonuniformity of the electric field in air discharges, such as streamers, can influence the accuracy of spectroscopic diagnostic methods and hence the estimation of the peak electric field. In this work, we use a self-consistent streamer discharge model to investigate the spatial nonuniformity in streamer heads and streamer glows. We focus our analysis on air discharges at Atmospheric pressure and at the low pressure of the mesosphere. This approach is useful to investigate the spatial nonuniformity of laboratory discharges as well as sprite streamers and blue jet streamers, two types of transient luminous events taking place above thunderclouds. This characterization of the spatial nonuniformity of the electric field in air discharges allows us to develop two different spectroscopic diagnostic methods to estimate the peak electric field in cold plasmas. The commonly employed method to derive the peak electric field in streamer heads underestimates the electric field by about 40-50% as a consequence of the high spatial nonuniformity of the electric field. Our diagnostic methods reduce this underestimation to about 10-20%. However, our methods are less accurate than previous methods for streamer glows, where the electric field is uniformly distributed in space. Finally, we apply our diagnostic methods to the measured optical signals in the second positive system of N2 and the first negative system of N2+ of sprites recorded by Armstrong et al. (1998, https://doi.org/10.1016/S1364-6826(98)00026-1) during the SPRITE's 1995 and 1996 campaigns.
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upper Atmospheric Electricity in giant gaseous planets the case of saturn
European Planetary Science Congress, 2013Co-Authors: Alejandro Luque, Yoav Yair, D Dubrovin, F J Gordillovazquez, Colin PriceAbstract:We discuss the ligthning-induced coupling between lower and upper layers of the atmospheres of giant gaseous planets. Taking Saturn as the best characterized example, we investigate quasi-electrostatic and electromagnetic-pulse-driven effects of lightning on the lower ionosphere of this planet. We present scaling arguments and numerical results about the relevance of electromagnetic pulses in Saturn.