Atmospheric Electrification in the Solar System

Atmospheric electrification is not a purely terrestrial phenomenon: all Solar System planetary atmospheres become slightly electrified by cosmic ray ionisation. There is evidence for lightning on Jupiter, Saturn, Uranus and Neptune, and it is possible on Mars, Venus and Titan. Controversy surrounds the role of atmospheric electricity in physical climate processes on Earth; here, a comparative approach is employed to review the role of electrification in the atmospheres of other planets and their moons. This paper reviews the theory, and, where available, measurements, of planetary atmospheric electricity which is taken to include ion production and ion–aerosol interactions. The conditions necessary for a planetary atmospheric electric circuit similar to Earth’s, and the likelihood of meeting these conditions in other planetary atmospheres, are briefly discussed. Atmospheric electrification could be important throughout the solar system, particularly at the outer planets which receive little solar radiation, increasing the relative significance of electrical forces. Nucleation onto atmospheric ions has been predicted to affect the evolution and lifetime of haze layers on Titan, Neptune and Triton. Atmospheric electrical processes on Titan, before the arrival of the Huygens probe, are summarised. For planets closer to Earth, heating from solar radiation dominates atmospheric circulations. However, Mars may have a global circuit analogous to the terrestrial model, but based on electrical discharges from dust storms. There is an increasing need for direct measurements of planetary atmospheric electrification, in particular on Mars, to assess the risk for future unmanned and manned missions. Theoretical understanding could be increased by cross-disciplinary work to modify and update models and parameterisations initially developed for a specific atmosphere, to make them more broadly applicable to other planetary atmospheres.     

强磁暴的时间分布特性

对比分析1957--2008年间Dst≤-100nT的强磁暴数与太阳黑子数的变化趋势,发现太阳黑子数和Dst≤-100nT的强磁暴数的变化趋势有很好的一致性。进一步统计强磁暴在太阳周不同阶段的分布后发现,同一太阳周内60％以上的强磁暴出现在下降年,但从太阳周各个阶段的平均磁暴年发生率来看,强磁暴平均年发生率最高的年份仍然是太阳活动极大年。     

The Global Atmospheric Electrical Circuit and Climate

Evidence is emerging for physical links among clouds, global temperatures, the global atmospheric electrical circuit and cosmic ray ionisation. The global circuit extends throughout the atmosphere from the planetary surface to the lower layers of the ionosphere. Cosmic rays are the principal source of atmospheric ions away from the continental boundary layer: the ions formed permit a vertical conduction current to flow in the fair weather part of the global circuit. Through the (inverse) solar modulation of cosmic rays, the resulting columnar ionisation changes may allow the global circuit to convey a solar influence to meteorological phenomena of the lower atmosphere. Electrical effects on non-thunderstorm clouds have been proposed to occur via the ion-assisted formation of ultra-fine aerosol, which can grow to sizes able to act as cloud condensation nuclei, or through the increased ice nucleation capability of charged aerosols. Even small atmospheric electrical modulations on the aerosol size distribution can affect cloud properties and modify the radiative balance of the atmosphere, through changes communicated globally by the atmospheric electrical circuit. Despite a long history of work in related areas of geophysics, the direct and inverse relationships between the global circuit and global climate remain largely quantitatively unexplored. From reviewing atmospheric electrical measurements made over two centuries and possible paleoclimate proxies, global atmospheric electrical circuit variability should be expected on many timescales.     

Spatial and Temporal Dependence of Temperature Variations Induced by Atmospheric Pressure Variations in Shallow Underground Cavities

Pressure-induced temperature (PIT) variations are systematically observed in the atmosphere of underground cavities. Such PIT variations are due to the compressibility of the air, damped by heat exchange with the rock surface. It is important to characterize such processes for numerous applications, such as the preservation of painted caves or the assessment of the long-term stability of underground laboratories and underground waste repositories. In this paper we thoroughly study the spatiotemporal dependence of the PIT response versus frequency using vertical and horizontal profiles of temperature installed in an abandoned underground quarry located in Vincennes, near Paris. The PIT response varies from about 20 × 10^?3°C hPa^?1 at a frequency of 2 × 10^?4 Hz to 2–3 × 10^?3°C hPa^?1 at a frequency of one cycle per day. An analytical expression based on a simple heat exchange model accounts for the observed features of the PIT response and allows for correcting the measured time series, having standard deviations of about 10^?2°C, to residual variations with a standard deviation of about 2 × 10^?3°C. However, a frequency-dependent attenuation of the response, corresponding to a reduction in amplitude with a factor varying from 2 to 3, is observed near the walls. This effect is not included in the simple analytical expression, but it can be accounted for by a one-dimensional differential equation, solved numerically, where temperature variations in the atmosphere are damped by an effective radiative coupling with the rock surface, complemented by a diffusive coupling near the walls. The TIP response is observed to remain stable over several years, but a large transient enhancement of about a factor of two is observed near the roof at one location from July to October 2005. In a cavity located below the Paris Observatory, an additional contribution is identified in the PIT response function versus frequency for frequencies smaller than 2 × 10^?5 Hz. This contribution can be described using a modified analytical expression that includes the effect of heat diffusion into the surrounding rock. Using this expression, in this case also, the temperature time series can then be corrected, giving a residual standard deviation smaller than 1.6 × 10^?3°C. Transient temporal variations of the PIT response are observed in all sites, with possible nonlinear components in the PIT. Such effects are not properly understood at this stage, and limit the reduction of time series to standard deviations of the order of 2 × 10^?3°C, and consequently limit the search for new transient or seasonal temperature signals, for example due to the presence of tiny heat sources in the cavity or to geodynamical effects.     

Dependence of the Local Index of Annual Asymmetry for NmF2 on Solar Activity

Geomagnetism and Aeronomy - The dependence of the local annual asymmetry index AI on solar activity has been analyzed based on daily data on the noon values of the F2-layer maximum electron...     

The importance of energetic particle precipitation on the chemical composition of the middle atmosphere

An assessment is made of the relative contribution of certain classes of energetic particle precipitation to the chemical composition of the middle atmosphere with emphasis placed on the production of odd nitrogen and odd hydrogen species and their subsequent role in the catalytic removal of ozone. Galactic cosmic radiation is an important source of odd nitrogen in the lower stratosphere but since the peak energy deposition occurs below the region where catalytic removal of O₃ is most effective, it is questionable whether this mechanism is important in the overall terrestrial ozone budget. The precipitation of energetic solar protons can periodically produce dramatic enhancement in upper stratospheric NO. The long residence time of NO in this region of the atmosphere, where catalytic interaction with O₃ is also most effective, mandates that this mechanism be included in future modelling of the global distribution of O₃. Throughout the mesosphere the precipitation of energetic electrons from the outer radiation belt (60°70°) can sporadically act as a major local source of odd hydrogen and odd nitrogen leading to observable O₃ depletion. Future satellite studies should be directed at simultaneously measuring the precipitation flux and the concomitant atmosphere modification, and these results should be employed to develop more sophisticated models of this important coupling.     

Variations of Solar Activity Cycles in the Late Pleistocene Lacustrine Ribbon Clay Rhythms

Geomagnetism and Aeronomy - In order to study possible changes in solar activity in the remote transitional climatic period of Younger Dryas cooling (12 700–11 600 ± 100...     

Atmospheric Stability Effects on Penman-Monteith Evapotranspiration Estimates

This study explores surface-layer stability effects on the Penman-Monteith (P-M) method, one of the most widely used methods to estimate evapotranspiration (ET). Stability correction is applied to the original (neutral stability) formula by using atmospheric exchange coefficients developed by Louiset al. (1981). First, the effects of stability on the P-M formula are explored theoretically. ET is then computed from field data using both P-M formulas and the values are compared to measured ET from Bowen-ratio and lysimeter data. Theoretical investigation of the P-M formula is performed by varying stability conditions for a range of vapor pressure deficit and canopy conductance. Infinitely large canopy conductance (zero canopy resistance) gives potential ET with results similar to Mahrt and Ek (1984): the stability-dependent formula gives larger (smaller) potential ET than the original formula under unstable (stable) conditions. For finite canopy conductance, ET behaves differently from potential ET as a result of coupling between canopy and atmospheric conductances. Stability-dependent ET values become smaller than the original formula values under extreme unstable conditions (when atmospheric conductance becomes large compared to canopy conductance) because stability-dependent sensible heat flux is considerably larger than its neutral counterpart under same net input energy. Field data collected during both wet and dry growing seasons indicate that both P-M formulas track the Bowen-ET estimates and lysimeter measurements quite closely.     

Synchronous Variations in the Atmospheric Pressure and Electric Field during the Passage of the Solar Terminator

Geomagnetism and Aeronomy - The paper presents the field observation data on variations in the pressure and electric field intensity in the near-surface atmospheric layer during the passage of the...     

Impact of strong geomagnetic storms on total ozone at southern higher middle latitudes

The effects of space weather on the magnetosphere-ionosphere-atmosphere system have been broadly studied within the program CAWSES (Climate and Weather of the Sun-Earth System) and project COST724. Here we show that strong geomagnetic storms do not affect total ozone at higher middle latitudes of the Southern Hemisphere contrary to the Northern Hemisphere, where an effect is observed under specific conditions.     

Global magnetic field of the Sun and long-term variations of galactic cosmic rays

The paper deals with the relation of long-term variations of 10 GV galactic cosmic rays (GCR) to the global solar magnetic field and solar wind parameters. This study continues previous works, where the tilt of the heliospheric current sheet (HCS) and other solar-heliospheric parameters are successfully used to describe long-term variations of cosmic rays in the past two solar cycles. The novelty of the present work is the use of the HCS tilt and other parameters reconstructed from Hα observations of filaments for the period when direct global solar magnetic field observations were unavailable. Thus, we could extend the GCR simulation interval back to 1953. The analysis of data for 1953–1999 revealed a good correlation (the correlation coefficient >0.88) between the solar-heliospheric parameters and GCR in different cycles of solar activity. Moreover, the approach applied makes it possible to describe the behavior of cosmic rays in the epochs of solar maxima, which could not be done before. This indicates both the adequacy of the model and the reliability of the reconstructed global solar magnetic field parameters.     

Comments on Modelling Short Atmospheric Frontal Waves

The idea of Gerstner's trochoidal waves is used to reconstruct a model of short, finite-amplitude progressive waves on frontal surfaces of the Margules Type. Stable waves associated with a negative (westward) group velocity occur in the model. A wave train can be maintained through the formation of new waves in the rear of the existing waves as a result of the westward energy transport.     

Solar Activity,Galactic Cosmic Ray Variations,and the Global Seismicity of the Earth

Geomagnetism and Aeronomy - A comparative analysis of the correlation between the number of strong (magnitude M ≥ 5.0), crustal (hypocenter depth 0 ≤ h ≤ 60 km) earthquakes per...     

Dynamic Characteristics of Area Variations of Small and Large Sunspots and Quasi-Biennial Oscillations in Solar Activity

The spatiotemporal and chaotic dynamics of variations in area of sunspot groups related conventionally to small (area <50 Msh) and large (area >50 Msh) populations is analyzed. The Greenwich Observatory–Marshall Space Flight Center data were used. The results show that both sunspot populations have a single initial source, which is a magnetic flux generated by the dynamo process (presumably at the bottom of the convective zone) and is responsible for the 11—22-year periodicity of solar activity. A possible explanation of the revealed different behavior of the considered populations is that the magnetic flux is partially involved in another process responsible for the shaping of primarily very large sunspot groups. This process develops presumably in the upper layer of the convective zone with an unstable amplitude and a period varying within 1–2 years. The analysis of power spectrum of the Wolf number time series has indicated the difference between dynamic characteristics of the two studied processes.     

Dependence of Groundwater Flow Direction on Variations in Its Salinity

The direction of motion of groundwater with a varying salinity is shown to depend on the spatial position of equal-salinity surfaces (planes), along the slopes of which groundwater motion takes place. The equations required for the solution of such problems are given. The procedure is exemplified by estimating the direction of groundwater motion in the western part of the Moscow Artesian Basin.     

Spatial Structure and Long-Term Variations of The Ground-Level Temperature Variance

The global distribution of the ground-level temperature variance and its long-term variations have been investigated on the basis of the monthly mean temperature anomalies, obtained from ground-based and sea-borne meteorological observations from 1896 to 1990. Particular characteristics of the large-scale structure of the temperature variance have been found. There are three pronounced maxima in the global distribution of the temperature variance: in Central Siberia (60°75°N and 70° 120°E), North America (60°75°N and –170°–120°E) and the Antarctica (50°65°S and –60°10°E, where and are the geographic latitude and longitude, respectively) and there are two minima: over the Atlantic and Pacific Ocean areas. The minimum over the Pacific is not as pronounced, as over the Atlantic. The spatial pattern of the ground-level temperature variance is, on the whole, stable, the positions of the zones of extrema remaining practically unchanged over a long time interval. These results indirectly corroborate the mechanism of solar impact on the properties of the low atmosphere by the modulation of the flux of galactic cosmic rays. The mechanism accounts for the spatial distribution of the temperature variance as a result of combined effect of solar activity and ocean. Long-term variations of the Siberian maximum of the ground-level temperature variance agree with the changing duration of the sunspot cycle, in contrast to the North American maximum.     

Measurement of Solar and Cosmic Radiation during Spaceflight

The external platform of the International Space Station (ISS) will provide aunique opportunity for exobiological studies under space conditions, e.g., spacevacuum, solar UV radiation, cosmic radiation, and temperature extremes. In orderto facilitate this research, ESA is developing the EXPOSE facility to be attachedto the External Pallet of the truss structure of the ISS. The experiment is plannedfor a duration of 18 months during the ISS early utilization period. Experimentson the ``Responses of Organisms to the Space Environment (ROSE)' will studythe survival of spores from bacteria, fungi, ferns, etc., under space conditions andthus investigate whether life could potentially survive extended travel through space.In parallel to the exposure of the biological material, the charged particle and solarextraterrestrial radiation will be measured with a multichannel dosimeter. Thisinstrument is based on two separate developments. The dosimeter which determinessolar radiation in four channels is based on the ground-based ELDONET (Europeanlight dosimeter network) instrument which has been developed to measure solar UVand visible radiation in three channels. The other part of the instrument is based on a256 channel dosimeter of cosmic radiation which was developed and used on theRussian space station Mir. A final miniature prototype has been developed to fit thespace available. The instrument incorporates the latest technologies such as SurfaceMounted Devices (SMDs), switchable amplifiers, as well as on-board microprocessorcontrol. Several software packages have been developed to record the solar visible andUV, and charged particle, radiations, to display them in graphical form and to store them for future analysis. All recorded data will be made available to the public via the Internet.     

地球物理场观测中的大气效应问题研究

作用在地表的大气质量不仅产生引力位的扰动，而且会引起各种地球物理场的附加效应，本文综述了近年来国内外同行在研究地表位移、重力、倾斜和应变固体潮观测中实施的大气效应改正问题，包括利用台站气压资料建立的实测模型，建立大气重力格林函数，利用全球和区域气象数据计算大气效应，建立大气改正的误差模型等，最后文章讨论了今后研究展望。     

Correlation between Long-Term Variations in the Vertical Component of the Electric Field in Baikal and Solar Activity

The vertical component of the electric field along the surface–bottom baseline was measured for several years in the southwestern part of Baikal. The measurements revealed a correlation between long-term variations in the field that were interpreted as variations in the current in the hydrospheric segment of the global electric circuit with intermittent variations in the solar activity. However, the continuous measurement series were no longer than a year, which is shorter than the maximal quasi-period of the alternating variations. The first continuous two-year measurement series was made in 2014–2016. Its analysis shows quite strong variations with quasi-periods of up to 320 days, which correlate with variations in the solar X-ray flux. The effective delay of the correlation is about four days, which is evidence of an indirect effect of solar activity on the vertical current in the hydrosphere by rather slow atmospheric processes.     

Solar activity dependence of ionospheric electron content and slab thickness using different solar indices

Ionospheric electron content (IEC) and slab thickness () data for the period 1977 to 1980 from Lunping (23.03°N; 121.90°E subionospheric) have been examined for their solar activity dependence. Local noontime monthly means as well as values for the 5 QQ days in a month have been examined separately with different solar indices, namely: solar EUV flux (170–190 Å),S _{10.7 cm} flux and sun spot number (SSN) on a seasonal basis. Both IEC and parameters exhibit better correlation with solar EUV andS _{10.7 cm} fluxes than with SSN for all seasons. IEC increases linearly with both EUV andS _{10.7 cm} flux whereas with SSN it shows a distinct nonlinear relationship during all seasons in both monthly mean and 5 QQ days' values. This study indicates that for correlating and predicting the variations (especially the medium term) in the ionospheric parameters, both EUV andS _{10.7 cm} fluxes have an advantage over SSN.