bluuebunny/crossref_metadata_2025 huggingface dataset:
Beginning of the ozone recovery over Europe? − Analysis of the total ozone data from the ground-based observations, 1964−2004
Authors: Krzyścin J. W. , Jaroslawski J. , Rajewska-Więch B.
Published: June 2010

Abstract. The total ozone variations over Europe (~50° N) in the period 1964–2004 are analyzed for detection of signals of ozone recovery. The ozone deviations from the long-term monthly means (1964–1980) for selected European stations, where the ozone observations (by the Dobson spectrophotometers) have been carried out continuously for at least 3–4 decades, are averaged and examined by a regression model. A new method is proposed to disclose both the ozone trend variations and date of the trend turnaround. The regression model contains a piecewise linear trend component and the terms describing the ozone response to forcing by "natural" changes in the atmosphere. Standard proxies for the dynamically driven ozone variations are used. The Multivariate Adaptive Regression Splines (MARS) methodology and principal component analysis are used to find an optimal set of the explanatory variables and the trend pattern. The turnaround of the ozone trend in 1994 is suggested from the pattern of the piecewise linear trend component. Thus, the changes in the ozone mean level are calculated over the periods 1970–1994 and 1994–2003, for both the original time series and the time series having "natural" variations removed. Statistical significance of the changes are derived by bootstrapping. A first stage of recovery (according to the definition of the International Ozone Commission), i.e. lessening of a negative trend, is found over Europe. It seems possible that the increase in the ozone mean level since 1994 of about 1–2% is due to superposition of the "natural" processes. Comparison of the total ozone ground-based network (the Dobson and Brewer spectrophotometers) and the satellite (TOMS, version 8) data over Europe shows the small bias in the mean values for the period 1996–2004, but the differences between the daily ozone values from these instruments are not trendless, and this may hamper an identification of the next stage of the ozone recovery over Europe. Keywords. Atmospheric composition and structure (Middle atmosphere-composition and chemistry) – Meteorology and atmospheric dynamics (Climatology, Middle atmosphere dynamics)
Radar observations in the vicinity of pre-noon auroral arcs
Authors: Nilsson H. , Kozlovsky A. , Sergienko T. , Kotikov A.
Published: June 2010

Abstract. A combination of EISCAT incoherent scatter radar measurements, optical and magnetometer data is used to study the plasma in and around pre-noon structured precipitation and auroral arcs. Particular attention is paid to regions of comparatively low E-region density observed adjacent to arcs or structured precipitation in the EISCAT Svalbard radar field-aligned measurements. Comparison between luminosity and incoherent scatter electron density measurements shows that the low-density regions occur primarily due to the absence of diffuse precipitation rather than to a cavity formation process. Two cases of arcs and low density/luminosity regions are identified. The first is related to a strong Pc5 pulsation event, and the absence of diffuse precipitation is due to a large-scale modulation of the diffuse precipitation. In the second case the equatormost arc is on a shielding boundary and the low-density region coincides with a strong flow region just poleward of this arc. Regions of high electric field and low luminosity and conductance are observed prior to intensification of the structured precipitation in both cases. The ionospheric current is enhanced in the low conductance region, indicating that the strong electric fields do not result solely from ionospheric polarization electric fields, and thus are mainly driven by magnetospheric processes. The average energy of the precipitating electrons in the arcs and structured precipitation is, according to EISCAT measurements, 500eV and the energy spectra are similar for the pulsation and shielding cases. The average energy is thus significantly less than in the diffuse precipitation region which shows central CPS-like energy spectra. We suggest that the low ionospheric conductance of 0.7S in the low density regions is favorable for the arc formation process. This is in quantitative agreement with recent simulations of the ionospheric feedback instability. Keywords. Magnetospheric physics (Auroral phenomena; Magnetosphere-ionosphere interactions) – Ionosphere (Plasma convection)
Proton isotropy boundaries as measured on mid- and low-altitude satellites
Authors: Ganushkina N. Yu. , Pulkkinen T. I. , Kubyshkina M. V. , Sergeev V. A. , Lvova E. A. , Yahnina T. A. , Yahnin A. G. , Fritz T.
Published: June 2010

Abstract. Polar CAMMICE MICS proton pitch angle distributions with energies of 31-80 keV were analyzed to determine the locations where anisotropic pitch angle distributions (perpendicular flux dominating) change to isotropic distributions. We compared the positions of these mid-altitude isotropic distribution boundaries (IDB) for different activity conditions with low-altitude isotropic boundaries (IB) observed by NOAA 12. Although the obtained statistical properties of IDBs were quite similar to those of IBs, a small difference in latitudes, most pronounced on the nightside and dayside, was found. We selected several events during which simultaneous observations in the same local time sector were available from Polar at mid-altitudes, and NOAA or DMSP at low-altitudes. Magnetic field mapping using the Tsyganenko T01 model with the observed solar wind input parameters showed that the low- and mid-altitude isotropization boundaries were closely located, which leads us to suggest that the Polar IDB and low-altitude IBs are related. Furthermore, we introduced a procedure to control the difference between the observed and model magnetic field to reduce the large scatter in the mapping. We showed that the isotropic distribution boundary (IDB) lies in the region where Rc/ρ~6, that is at the boundary of the region where the non-adiabatic pitch angle scattering is strong enough. We therefore conclude that the scattering in the large field line curvature regions in the nightside current sheet is the main mechanism producing isotropization for the main portion of proton population in the tail current sheet. This mechanism controls the observed positions of both IB and IDB boundaries. Thus, this tail region can be probed, in its turn, with observations of these isotropy boundaries. Keywords. Magnetospheric physics (Energetic particles, Precipitating; Magnetospheric configuration and dynamics; Magnetotail)
First current density measurements in the ring current region using simultaneous multi-spacecraft CLUSTER-FGM data
Authors: Vallat C. , Dandouras I. , Dunlop M. , Balogh A. , Lucek E. , Parks G. K. , Wilber M. , Roelof E. C. , Chanteur G. , Rème H.
Published: June 2010

Abstract. The inner magnetosphere's current mapping is one of the key elements for current loop closure inside the entire magnetosphere. A method for directly computing the current is the multi-spacecraft curlometer technique, which is based on the application of Maxwell-Ampère's law. This requires the use of four-point magnetic field high resolution measurements. The FGM experiment on board the four Cluster spacecraft allows, for the first time, an instantaneous calculation of the magnetic field gradients and thus a measurement of the local current density. This technique requires, however, a careful study concerning all the factors that can affect the accuracy of the J estimate, such as the tetrahedral geometry of the four spacecraft, or the size and orientation of the current structure sampled. The first part of this paper is thus providing a detailed analysis of the method accuracy, and points out the limitations of this technique in the region of interest. The second part is an analysis of the ring current region, which reveals, for the first time, the large latitudinal extent of the ring current, for all magnetic activity levels, as well as the latitudinal evolution of the perpendicular (and parallel) components of the current along the diffuse auroral zone. Our analysis also points out the sharp transition between two distinct plasma regions, with the existence of high diamagnetic currents at the interface, as well as the filamentation of the current inside the inner plasma sheet. A statistical study over multiple perigee passes of Cluster (at about 4 RE from the Earth) reveals the azimuthal extent of the partial ring current. It also reveals that, at these distances and all along the evening sector, there isn't necessarily a strong dependence of the local current density value on the magnetic activity level. This is a direct consequence of the ring current morphology evolution, as well as the relative positioning of the spacecraft with respect to the bulk of the ring current. It also proves the existence of a substantial ring current at these distances, all over the evening and the post-midnight sector. Keywords. Magnetospheric physics (Current systems; Energetic particles, trapped; Magnetospheric configuration and dynamics)
Statistics of high-altitude and high-latitude O+ ion outflows observed by Cluster/CIS
Authors: Arvelius S. , Yamauchi M. , Nilsson H. , Lundin R. , Hobara Y. , Rème H. , Bavassano-Cattaneo M.B. , Paschmann G. , Korth A. , Kistler L. M. , Parks G. K.
Published: June 2010

Abstract. The persistent outflows of O+ ions observed by the Cluster CIS/CODIF instrument were studied statistically in the high-altitude (from 3 up to 11 RE) and high-latitude (from 70 to ~90 deg invariant latitude, ILAT) polar region. The principal results are: (1) Outflowing O+ ions with more than 1keV are observed above 10 RE geocentric distance and above 85deg ILAT location; (2) at 6-8 RE geocentric distance, the latitudinal distribution of O+ ion outflow is consistent with velocity filter dispersion from a source equatorward and below the spacecraft (e.g. the cusp/cleft); (3) however, at 8-12 RE geocentric distance the distribution of O+ outflows cannot be explained by velocity filter only. The results suggest that additional energization or acceleration processes for outflowing O+ ions occur at high altitudes and high latitudes in the dayside polar region. Keywords. Magnetospheric physics (Magnetospheric configuration and dynamics, Solar wind-magnetosphere interactions)
Magnetospheric energy inputs into the upper atmospheres of the giant planets
Authors: Smith C. G. A. , Miller S. , Aylward A. D.
Published: June 2010

Abstract. We revisit the effects of Joule heating upon the upper atmospheres of Jupiter and Saturn. We show that in addition to direct Joule heating there is an additional input of kinetic energy – ion drag energy – which we quantify relative to the Joule heating. We also show that fluctuations about the mean electric field, as observed in the Earth's ionosphere, may significantly increase the Joule heating itself. For physically plausible parameters these effects may increase previous estimates of the upper atmospheric energy input at Saturn from ~10 TW to ~20 TW. Keywords. Ionosphere (Electric fields and currents; Planetary ionosphere) – Magnetospheric physics (Auroral phenomena)
Letter to the EditorOn the use of the sunspot number for the estimation of past solar and upper atmosphere conditions from historical and modern auroral observations
Authors:   Vaquero
Published: June 2010

Abstract. In this short contribution the use of different sunspot numbers for the estimation of past solar and upper atmosphere conditions from historical and modern auroral observations realised by Schröder et al. (2004) is analysed. Moreover, some comments are made on the relationships between mean annual visual observations of the auroras at middle latitudes of Europe and the mean annual sunspot number during 1780–1829. Keywords. Atmospheric composition and structure (Airglow and aurora) – Magnetospheric physics (Auroral phenomena, solar wind-magnetosphere interactions) – History of geophysics (Solar-planetary relationship)
Vertical structure of extreme currents in the Faroe-Bank Channel
Authors: Carollo C. , Astin I. , Graff J.
Published: June 2010

Abstract. Extreme currents are studied with the aim of understanding their vertical and spatial structures in the Faroe-Bank Channel. Acoustic Doppler Current Profiler time series recorded in 3 deployments in this channel were investigated. To understand the main features of extreme events, the measurements were separated into their components through filtering and tidal analysis before applying the extreme value theory to the surge component. The Generalized Extreme Value (GEV) distribution and the Generalized Pareto Distribution (GPD) were used to study the variation of surge extremes from near-surface to deep waters. It was found that this component alone is not able to explain the extremes measured in total currents, particularly below 500 m. Here the mean residual flow enhanced by tidal rectification was found to be the component feature dominating extremes. Therefore, it must be taken into consideration when applying the extreme value theory, not to underestimate the return level for total currents. Return value speeds up to 250 cm s–1 for 50/250 years return period were found for deep waters, where the flow is constrained by the topography at bearings near 300/330° It is also found that the UK Meteorological Office FOAM model is unable to reproduce either the magnitude or the form for the extremes, perhaps due to its coarse vertical and horizontal resolution, and is thus not suitable to model extremes on a regional scale. Keywords. Oceanography: Physical (Currents; General circulation; General or miscellaneous)
Further signatures of long-term changes in atmospheric electrical parameters observed in Europe
Authors: Märcz F. , Harrison R. G.
Published: June 2010

Abstract. Long-term decreases found recently in both the atmospheric electrical potential gradient (PG) and the air-Earth current density (Jz), using observation series from the UK and Hungary, have motivated studies of other European data. Two surface data series somewhat longer than a decade were available: PG data obtained at Serra do Pilar (Portugal), and PG, Jz and positive air conductivity measurements at Athens (Greece). Selecting data to minimise local effects, the 1960–1971 Serra do Pilar PG values decrease at dawn and in the evening. Dawn data obtained at Athens (1967–1977) indicate a reduction in Jz, while the simultaneous PG values there increase (coincident air conductivity values decrease) for the periods investigated. The Athens PG increase is attributed to local aerosol influences, typical of urban environments. Despite the urban influence, the Athens Jz shows similarities with soundings of the ionospheric potential. The decline in Jz at Athens occurs simultaneously with a decrease reported previously in Jz at Kew (UK), indicating that, at least, a regional decrease in the global atmospheric electrical circuit occurred during part of the twentieth century. Similar surface changes occur in European atmospheric electrical parameters, with a decrease of about 0.5% to 0.7% per year between 1920 and 1970 (possibly extending back to 1898), an annual decrease of between 2.7 and 3.4%, between 1959 and 1971 and a continued decrease of about ~1% per year between 1967 and 1984, possibly still continuing. Keywords. Meteorology and atmospheric dynamics (Atmospheric electricity) – Geomagnetism and paleomagnetism (Time variations, secular and long term) – Atmospheric composition and structure (Aerosols and particles)
Sea level variability at Adriatic coast and its relationship to atmospheric forcing
Authors: Bergant K. , Sušnik M. , Strojan I. , Shaw A. G. P.
Published: June 2010

Abstract. Sea level (SLH) variability at the Adriatic coast was investigated for the period 1872–2001 using monthly average values of observations at 13 tide gauge stations. Linear trends and seasonal cycles were investigated first and removed afterwards from the data. Empirical Orthogonal Functions (EOF) analysis was used further on remaining anomalies (SLA) to extract the regional intermonthly variability of SLH. It was found that the leading EOF and its principal component (PC) explain a major part of SLA variability (92%). The correlation between the reconstructed SLA, based on leading EOF and its PC, and overlapping observed SLA values for selected tide gauge stations is between 0.93 and 0.99. Actual SLH values at tide gauge stations can be reconstructed and some gaps in the data can be filled in on the basis of estimated SLA values if reasonable estimates of long-term trends and seasonal cycles are also available. A strong, seasonally dependent relationship between SLA at the Adriatic coast and atmospheric forcing, represented by sea level pressure (SLP) fields, was also found. Comparing the time series of leading PC and gridded SLP data for the period 1948–2001, the highest correlation coefficients (r) of –0.92 in winter, –0.84 in spring, –0.66 in summer, and –0.91 in autumn were estimated for a SLP grid point located in northern Italy. The SLP variability on this grid point contains information about the isostatic response of the sea level at the Adriatic coast, but can also be treated as a sort of teleconnection index representing the large-scale SLP variability across central and southern Europe. To some extent the large-scale SLP variability that affects the SLA at the Adriatic coast can be related to the North Atlantic Oscillation (NAO), because significant correlations were found between the NAO index and the first PC of SLA (rwinter=–0.56, rspring=–0.45, rsummer=–0.48, and rautumn=–0.43) for the period 1872–2001. The use of partial least-squares (PLS) regression between large-scale SLP fields and SLA only slightly improved the description of the SLA dependence on SLP forcing in comparison to the single grid point approach. A strong relationship between atmospheric pressure and the sea level could represent an additional possibility for filling in the gaps in the tide gauge data. Keywords. Oceanography: general (Climate and interannual variability) – Oceanography: physical (Air-sea interactions; sea level variations)
Seven year satellite observations of the mean structures and variabilities in the regional aerosol distribution over the oceanic areas around the Indian subcontinent
Authors: Nair S. K. , Parameswaran K. , Rajeev K.
Published: June 2010

Abstract. Aerosol distribution over the oceanic regions around the Indian subcontinent and its seasonal and interannual variabilities are studied using the aerosol optical depth (AOD) derived from NOAA-14 and NOAA-16 AVHRR data for the period of November 1995–December 2003. The air-mass types over this region during the Asian summer monsoon season (June–September) are significantly different from those during the Asian dry season (November–April). Hence, the aerosol loading and its properties over these oceanic regions are also distinctly different in these two periods. During the Asian dry season, the Arabian Sea and Bay of Bengal are dominated by the transport of aerosols from Northern Hemispheric landmasses, mainly the Indian subcontinent, Southeast Asia and Arabia. This aerosol transport is rather weak in the early part of the dry season (November–January) compared to that in the later period (February–April). Large-scale transport of mineral dust from Arabia and the production of sea-salt aerosols, due to high surface wind speeds, contribute to the high aerosol loading over the Arabian Sea region during the summer monsoon season. As a result, the monthly mean AOD over the Arabian Sea shows a clear annual cycle with the highest values occurring in July. The AOD over the Bay of Bengal and the Southern Hemisphere Indian Ocean also displays an annual cycle with maxima during March and October, respectively. The amplitude of the annual variation is the largest in coastal Arabia and the least in the Southern Hemisphere Indian Ocean. The interannual variability in AOD is the largest over the Southeast Arabian Sea (seasonal mean AOD varies from 0.19 to 0.42) and the northern Bay of Bengal (seasonal mean AOD varies from 0.24 to 0.39) during the February–April period and is the least over the Southern Hemisphere Indian Ocean. This study also investigates the altitude regions and pathways of dominant aerosol transport by combining the AOD distribution with the atmospheric circulation. Keywords. Atmospheric composition and structure (Aerosols and particles) – Meteorology and atmospheric dynamics (Climatology) – Oceanography: physical (Ocean fog and aerosols)
Sampling of an STT event over the Eastern Mediterranean region by lidar and electrochemical sonde
Authors: Papayannis A. , Balis D. , Zanis P. , Galani E. , Wernli H. , Zerefos C. , Stohl A. , Eckhardt S. , Amiridis V.
Published: June 2010

Abstract. A two-wavelength ultraviolet (289–316nm) ozone Differential Absorption Lidar (DIAL) system is used to perform ozone measurements in the free troposphere in the Eastern Mediterranean (Northern Greece). The ozone DIAL profiles obtained during a Stratosphere-to-Troposphere Transport (STT) event are compared to that acquired by an electrochemical ozonesonde, in the altitude range between 2 and 10 km. The measurement accuracy of these two instruments is also discussed. The mean difference between the ozone profiles obtained by the two techniques is of the order of 1.11 ppbv (1.86%), while the corresponding standard deviation is 4.69 ppbv (8.16%). A case study of an STT event which occurred on 29 November 2000 is presented and analyzed, using ozone lidar, satellite and meteorological data, as well as air mass back-trajectory analysis. During this STT event ozone mixing ratios of 55–65 ppbv were observed between 5 and 7 km height above sea level (a.s.l.). Stratospheric air was mixed with tropospheric air masses, leading to potential vorticity (PV) losses due to diabatic processes. The ozone DIAL system can be used for following STT events and small-scale mixing phenomena in the free troposphere, and for providing sequences of vertical ozone profiles in the free troposphere. Keywords. Atmospheric composition and structure (Evolution of the atmosphere; Instruments and techniques) – Meteorology and atmospheric dynamics (Middle atmosphere dynamics; Turbulence)
Statistical study of the substorm onset: its dependence on solar wind parameters and solar illumination
Authors: Wang H. , Lühr H. , Ma S. Y. , Ritter P.
Published: June 2010

Abstract. Based on 1829 well-defined substorm onsets in the Northern Hemisphere, observed during a 2-year period by the FUV Imager on board the IMAGE spacecraft, a statistical study is performed. From the combination of solar wind parameter observations by ACE and magnetic field observations by the low altitude satellite CHAMP, the location of auroral breakups in response to solar illumination and solar coupling parameters are studied. Furthermore, the correspondence of the onset location with prominent large-scale field-aligned currents and electrojets are investigated. Solar illumination and the related ionospheric conductivity have significant effects on the most probable substorm onset latitude and local time. In sunlight, substorm onsets tend to occur 1h earlier in local time and 1.5° more poleward than in darkness. The solar wind input, represented by the merging electric field, integrated over 1h prior to the substorm, correlates well with the latitude of the breakup. Most poleward latitudes of the onsets are found to range around 73° magnetic latitude during very quiet times. Field-aligned and Hall currents observed concurrently with the onset are consistent with the signature of a westward travelling surge evolving out of the Harang discontinuity. The observations suggest that the ionospheric conductivity has an influence on the location of the precipitating energetic electron which causes the auroral break-up signature. Keywords. Ionosphere (Auroral ionosphere) – Magnetospheric Physics (Current systems; Magnetosphereionosphere interactions)
Energetic particle fluxes in the exterior cusp and the high-latitude dayside magnetosphere: statistical results from the Cluster/RAPID instrument
Authors: Asikainen T. , Mursula K.
Published: June 2010

Abstract. In this paper we study the fluxes of energetic protons (30–4000 keV) and electrons (20–400 keV) in the exterior cusp and in the adjacent high-latitude dayside plasma sheet (HLPS) with the Cluster/RAPID instrument. Using two sample orbits we demonstrate that the Cluster observations at high latitudes can be dramatically different because the satellite orbit traverses different plasma regions for different external conditions. We make a statistical study of energetic particles in the exterior cusp and HLPS by analysing all outbound Cluster dayside passes in February and March, 2002 and 2003. The average particle fluxes in HLPS are roughly three (protons) or ten (electrons) times larger than in the exterior cusp. This is also true on those Cluster orbits where both regions are visited within a short time interval. Moreover, the total electron fluxes, as well as proton fluxes above some 100 keV, in these two regions correlate with each other. This is true even for fluxes in every energy channel when considered separately. The spectral indices of electron and proton fluxes are the same in the two regions. We also examine the possible dependence of particle fluxes at different energies on the external (solar wind and IMF) and internal (geomagnetic) conditions. The energetic proton fluxes (but not electron fluxes) in the cusp behave differently at low and high energies. At low energies (<70 keV), the fluxes increase strongly with the magnitude of IMF By. Instead, at higher energies the proton fluxes in the cusp depend on substorm/geomagnetic activity. In HLPS proton fluxes, irrespective of energy, depend strongly on the Kp and AE indices. The electron fluxes in HLPS depend both on the <Kp index and the solar wind speed. In the cusp the electron fluxes mainly depend on the solar wind speed, and are higher for northward than southward IMF. These results give strong evidence in favour of the idea that the high-latitude dayside plasma sheet is the main source of energetic particles in the exterior cusp. Energetic particles can reach HLPS from the near-Earth tail. The closed field lines of HLPS act as storage for these particles. Direct diffusion (for electrons and high-energy protons) and magnetic reconnection in the high-latitude magnetopause near HLPS (for low energy protons) control the number of particles released into the exterior cusp. Note that this explanation, in contrast to other suggested theories, works both for the energetic protons and electrons in the exterior cusp. Keywords. Magnetospheric physics (Magnetopause, cusp and boundary layers; Solar wind-magnetosphere interactions) – Space plasma physics (magnetic reconnection)
Optical observations geomagnetically conjugate to sprite-producing lightning discharges
Authors: Marshall R. A. , Inan U. S. , Neubert T. , Hughes A. , Sátori G. , Bór J. , Collier A. , Allin T. H.
Published: June 2010

Abstract. Theoretical studies have predicted that large positive cloud-to-ground discharges can trigger a runaway avalanche process of relativistic electrons, forming a geomagnetically trapped electron beam. The beam may undergo pitch angle and energy scattering during its traverse of the Earth's magnetosphere, with a small percentage of electrons remaining in the loss cone and precipitating in the magnetically conjugate atmosphere. In particular, N2 1P and N2+1N optical emissions are expected to be observable. In July and August 2003, an attempt was made to detect these optical emissions, called "conjugate sprites", in correlation with sprite observations in Europe near . Sprite observations were made from the Observatoire du Pic du Midi (OMP) in the French Pyrenées, and VLF receivers were installed in Europe to detect causative sferics and ionospheric disturbances associated with sprites. In the Southern Hemisphere conjugate region, the Wide-angle Array for Sprite Photometry (WASP) was deployed at the South African Astronomical Observatory (SAAO), near Sutherland, South Africa, to observe optical emissions with a field-of-view magnetically conjugate to the Northern Hemisphere observing region. Observations at OMP revealed over 130 documented sprites, with WASP observations covering the conjugate region successfully for 30 of these events. However, no incidences of optical emissions in the conjugate hemisphere were found. Analysis of the conjugate optical data from SAAO, along with ELF energy measurements from Palmer Station, Antarctica, and charge-moment analysis, show that the lightning events during the course of this experiment likely had insufficient intensity to create a relativistic beam. Keywords. Ionosphere (Ionsophere-magnetosphere interactions; Ionospheric disturbances; Instruments and techniques)
Gamma rays in L-B coordinates at CORONAS-I altitude
Authors: Bučík R. , Kudela K. , Kuznetsov S. N. , Myagkova I. N.
Published: June 2010

Abstract. We present here observations of gamma rays in the energy range between 3.0 and 8.3 MeV gathered by the SONG instrument aboard low-altitude polar-orbiting satellite CORONAS-I throughout the period March-June 1994. We concentrate on the emissions related to the trapped particles and organize CORONAS-I measurements in the magnetic L–B coordinate system. The spatial distribution of the average gamma-ray counts reveals that the most intense fluxes were observed under the inner radiation belt, at L<2, and that they are exclusively confined into the region of stably trapped particles, where daughter gamma rays could result from the interactions within the spacecraft and instrumental matter. In the outer radiation zone (L~4), the enhanced gamma radiation, also detected outside the stably trapping region, shows pronounced longitudinal variations. The observed eastward increase in the gamma-ray count rate suggests quasi-traped energetic (megavolt) electrons as a source of the gamma rays both in the upper atmosphere and in the satellite matter, most likely, through the bremsstrahlung process in the studied energy domain. Keywords. Magnetospheric physics (Energetic particles, precipitating; Energetic particles, trapped; Magnetosphereionosphere interactions)
On the development and evolution of nonlinear ion acoustic wave packets
Authors: Hamza A. M.
Published: June 2010

Abstract. A simple model of ion fluctuations (ion acoustic and ion cyclotron fluctuations for example) driven by an electron current which leads to intermittent fluctuations when the linear growth rate exceeds the wave packet dispersion rate is analized. The normalized fluctuation amplitude eφ0/T can be much larger than the mass ratio (me/mi) level predicted by the conventional quasilinear theory or Manheimer's theory (see references in this document), and where φ0 represents the amplitude of the main peak of the ion fluctuations. Although the ion motion is linear, intermittency is produced by the strong nonlinear electron response, which causes the electron momentum input to the ion fluctuations to be spatially localized. We treat the 1-D case because it is especially simple from an intuitive and analytical point of view, but it is readily apparent and one can put forward the conjecture that the effect occurs in a three dimensional magnetized plasma. The 1-D analysis, as shown in this manuscript will clearly help identify the subtle difference between turbulence as conventionally understood and intermittency as it occurs in space and laboratory plasmas. Keywords. Meteorology and atmospheric dynamics (Turbulence) – Ionosphere (Wave-particles interactions) – Space plasma physics (Waves and instabilities)
Observations of neutral winds, wind shears, and wave structure during a sporadic-E/QP event
Authors: Larsen M. F. , Yamamoto M. , Fukao S. , Tsunoda R. T. , Saito A.
Published: June 2010

Abstract. The second Sporadic E Experiment over Kyushu (SEEK-2) was carried out on 3 August 2002, during an active sporadic-E event that also showed quasi-periodic (QP) echoes. Two rockets were launched into the event from Kagoshima Space Center in southern Japan 15 min apart. Both carried a suite of instruments, but the second rocket also released a trimethyl aluminum (TMA) trail to measure the neutral winds and turbulence structure. In a number of earlier measurements in similar conditions, large winds and shears that were either unstable or close to instability were observed in the altitude range where the ionization layer occurred. The SEEK-2 wind measurements showed similar vertical structure, but unlike earlier experiments, there was a significant difference between the up-leg and down-leg wind profiles. In addition, wave or billow-like fluctuations were evident in the up-leg portion of the trail, while the lower portion of the down-leg trail was found to have extremely strong turbulence that led to a rapid break-up of the trail. The large east-west gradient in the winds and the strong turbulence have not been observed before. The wind profiles and shears, as well as the qualitative characteristics of the strong turbulence are presented, along with a discussion of the implications of the dynamical features. Keywords. Ionosphere (Mid-latitude ionosphere; Ionospheric irregularities; Electric field and currents)
Extreme summer temperatures in Iberia: health impacts and associated synoptic conditions
Authors: García-Herrera R. , Díaz J. , Trigo R. M. , Hernández E.
Published: June 2010

Abstract. This paper examines the effect of extreme summer temperatures on daily mortality in two large cities of Iberia: Lisbon (Portugal) and Madrid (Spain). Daily mortality and meteorological variables are analysed using the same methodology based on Box-Jenkins models. Results reveal that in both cases there is a triggering effect on mortality when maximum daily temperature exceeds a given threshold (34°C in Lisbon and 36°C in Madrid). The impact of most intense heat events is very similar for both cities, with significant mortality values occurring up to 3 days after the temperature threshold has been surpassed. This impact is measured as the percentual increase of mortality associated to a 1°C increase above the threshold temperature. In this respect, Lisbon shows a higher impact, 31%, as compared with Madrid at 21%. The difference can be attributed to demographic and socio-economic factors. Furthermore, the longer life span of Iberian women is critical to explain why, in both cities, females are more susceptible than males to heat effects, with an almost double mortality impact value. The analysis of Sea Level Pressure (SLP), 500hPa geopotential height and temperature fields reveals that, despite being relatively close to each other, Lisbon and Madrid have relatively different synoptic circulation anomalies associated with their respective extreme summer temperature days. The SLP field reveals higher anomalies for Lisbon, but extending over a smaller area. Extreme values in Madrid seem to require a more western location of the Azores High, embracing a greater area over Europe, even if it is not as deep as for Lisbon. The origin of the hot and dry air masses that usually lead to extreme heat days in both cities is located in Northern Africa. However, while Madrid maxima require wind blowing directly from the south, transporting heat from Southern Spain and Northern Africa, Lisbon maxima occur under more easterly conditions, when Northern African air flows over the central Iberian plateau, which had been previously heated.
Turbulence parameter estimations from high-resolution balloon temperature measurements of the MUTSI-2000 campaign
Authors: Gavrilov N. M. , Luce H. , Crochet M. , Dalaudier F. , Fukao S.
Published: June 2010

Abstract. Turbulence parameters in the tropo-stratosphere are analyzed using high-resolution balloon temperature measurements collected during the MUTSI (MU radar, Temperature sheets and Interferometry) campaign which took place near the Middle and Upper atmosphere (MU) radar (Japan, 35° N, 136° E) in May 2000. Vertical profiles of the specific dissipation rate of turbulent kinetic energy, ε, and turbulent diffusivity, K, are estimated from the Thorpe lengthscale, LT. The last is obtained by using two methods. The first one consists of measuring directly LT by reordering the potential temperature profiles. The second method is based on estimates of the temperature structure constant, CT2. A relationship between LT and CT2 can be found by assuming either adiabatic vertical displacements or a model based on turbulent energy balance consideration. Analysis shows that the adiabatic assumption gives indirect estimates of LT more consistent with direct measurements. We also found that vertical profiles of analyzed turbulence characteristics show substantial intermittency, leading to substantial scatter of the local, median and average values. General trends correspond to a decrease in ε and K from the boundary layer up to altitudes 20–25 km. Layers of increased turbulence are systematically observed in the tropo-stratosphere, which may be produced by instabilities of temperature and wind profiles. These maxima may substantially increase local values of turbulence diffusivity. Keywords. Meteorology and atmospheric dynamics (Turbulence)
Long-term trends in solar radiation and the associated climatic factors over China for 1961-2000
Authors: Liang F. , Xia X. A.
Published: June 2010

Abstract. Long-term trends in downwelling solar irradiance and associated climatic factors over China are studied in the paper. Decreasing trends in global and direct radiation are observed over much of China. The largest decrease occurs in South and East China (east of about 100° E and south of about 40° N). The spatial pattern of observed trends in diffuse irradiance is complex and inhomogeneous. An intriguing aspect of trends in global and direct irradiance is the rather abrupt decrease in annual and seasonal mean values from 1978 onward. The decreasing trends in solar radiation in China did not persist into the 1990s. The spatial and temporal patterns of trends in sunshine duration are consistent with that of global and direct irradiance. A decreasing trend in rainy days is observed over much of China, which is in agreement with the secular trend in cloud amount. The fact that trends in cloud amount and solar radiation are quite similar suggests that the cloud amount is not the primary cause for the decrease in solar radiation. Visibility in the eastern part of China has deteriorated heavily as a result of the rapid increase in aerosol loading. The statistical analysis showed that atmospheric transmission under clear conditions decreased rapidly. These facts suggest that the rapid increase in aerosol loading should be one of the principle causes for the decrease in solar radiation. The observed diurnal temperature range decreases remarkably in China, which is closely related to the increase in aerosols. The effects of anthropogenic air pollutants on climate should be further studied and included in the simulation of climate and projection of climate scenario. Keywords. Atmospheric composition and structure (Aerosol and particles; General or miscellaneous) – Meteorology and atmospheric dynamics (Radiative processes)
A new approach to momentum flux determinations using SKiYMET meteor radars
Authors: Hocking W. K.
Published: June 2010

Abstract. The current primary radar method for determination of atmospheric momentum fluxes relies on multiple beam studies, usually using oppositely directed coplanar beams. Generally VHF and MF radars are used, and meteor radars have never been successfully employed. In this paper we introduce a new procedure that can be used for determination of gravity wave fluxes down to time scales of 2-3h, using the SKiYMET meteor radars. The method avoids the need for beam forming, and allows simultaneous determination of the three components of the wind averaged over the radar volume, as well as the variance and flux components , where refers to the fluctuating eastward wind, refers to the fluctuating northward wind, and refers to the fluctuating vertical wind. Data from radars in New Mexico and Resolute Bay are used to illustrate the data quality, and demonstrate theoretically expected seasonal forcing. Keywords. Meteorology and atmospheric dynamics (Middle atmosphere dynamics; Waves and tides; Climatology)
Observations in equatorial anomaly region of total electron content enhancements and depletions
Authors: Dashora N. , Pandey R.
Published: June 2010

Abstract. A GSV 4004A GPS receiver has been operational near the crest of the equatorial anomaly at Udaipur, India for some time now. The receiver provides the line-of-sight total electron content (TEC), the phase and amplitude scintillation index, σφ and S4, respectively. This paper presents the first results on the nighttime TEC depletions associated with the equatorial spread F in the Indian zone. The TEC depletions are found to be very well correlated with the increased S4 index. A new feature of low-latitude TEC is also reported, concerning the observation of isolated and localized TEC enhancements in the nighttime low-latitude ionosphere. The TEC enhancements are not correlated with the S4 index. The TEC enhancements have also been observed along with the TEC depletions. The TEC enhancements have been interpreted as the manifestation of the plasma density enhancements reported by Le et al. (2003). Keywords. Ionosphere (Equatorial ionosphere; Ionospheric irregularities)
VHF and L-band scintillation characteristics over an Indian low latitude station, Waltair (17.7° N, 83.3° E)
Authors: Rama Rao P. V. S. , Tulasi Ram S. , Niranjan K. , Prasad D. S. V. V. D , Gopi Krishna S. , Lakshmi N. K. M.
Published: June 2010

Abstract. Characteristics of simultaneous VHF (244 MHz) and L-band (1.5 GHz) scintillations recorded at a low-latitude station, Waltair (17.7° N, 83.3° E), during the low sunspot activity year of March 2004 to March 2005, suggest that the occurrence of scintillations is mainly due to two types, namely the Plasma Bubble Induced (PBI), which maximizes during the post sunset hours of winter and equinoctial months, and the Bottom Side Sinusoidal (BSS) type, which maximizes during the post-midnight hours of the summer solstice months. A detailed study on the spectral characteristics of the scintillations at both the frequencies show that the post-sunset scintillations are strong with fast fading (≈40 fad/min) and are multiple in nature in scattering, giving rise to steep spectral slopes, whereas the post-midnight scintillations, which occur mostly on the VHF signal with low fading rate (≈4 fad/min), are of the BSS type, often showing typical Fresnel oscillations with reduced roll off spectral slopes, indicating that the type of irregularity resembles a thin screen structure giving rise to weak scattering. Using the onset times of several similar scintillation patches across the two satellite (FLEETSAT 73° E, INMARSAT 65° E) ray paths (sub-ionospheric points are separated by 82 km), the East ward movement of the irregularity patches is found to vary from 150 to 250 m/s during the post sunset hours and decrease slowly during the post midnight hours. Further, the east-west extent of the PBI type of irregularities is found to vary from 100 to 500 km, while that of the BSS type extend up to a few thousand kilometers. Keywords. Ionosphere (Ionospheric irregularities; Auroral ionosphere; Electric fields and currents)
Manifestation of solar activity in the global topside ion composition − a study based on satellite data
Authors: Truhlík V. , Trísková L. , Šmilauer J.
Published: June 2010

Abstract. The solar cycle variation of the most important parameters characterizing the ion composition in the topside ionosphere is studied. For this purpose data from the ACTIVE mission (the IK-24 satellite) for the maximum of solar cycle 22 (aver F10.7~200), complemented by data available from the Atmosphere Explorer (AE) satellites, for the minimum of solar cycle 21 (average F10.7~85), were processed. OGO-6 data from the low maximum of solar cycle 20 (average F10.7~150) were used for medium solar activity conditions. The results for the equinox from the recently developed empirical model of ion composition are analyzed and presented, and typical vertical profiles from solar maxima and minima are shown. It was found that the logarithm of the O+, H+, He+, and N+ densities in the topside ionosphere at a fixed altitude, latitude, and local time is, in the first approximation, a linear function of solar activity characterized by the daily F10.7. On the other hand, the upper transition height is generally a non linear function of the daily F10.7, the deviation from linear dependence increases with latitude. Keywords. Ionosphere (Plasma temperature and density; Ion chemistry and composition; Modeling and forecasting)
The Double Star mission
Authors: Liu Z. X. , Escoubet C. P , Pu Z. , Laakso H. , Shi J. K. , Shen C. , Hapgood M.
Published: June 2010

Abstract. The Double Star Programme (DSP) was first proposed by China in March, 1997 at the Fragrant Hill Workshop on Space Science, Beijing, organized by the Chinese Academy of Science. It is the first mission in collaboration between China and ESA. The mission is made of two spacecraft to investigate the magnetospheric global processes and their response to the interplanetary disturbances in conjunction with the Cluster mission. The first spacecraft, TC-1 (Tan Ce means "Explorer"), was launched on 29 December 2003, and the second one, TC-2, on 25 July 2004 on board two Chinese Long March 2C rockets. TC-1 was injected in an equatorial orbit of 570x79000 km altitude with a 28° inclination and TC-2 in a polar orbit of 560x38000 km altitude. The orbits have been designed to complement the Cluster mission by maximizing the time when both Cluster and Double Star are in the same scientific regions. The two missions allow simultaneous observations of the Earth magnetosphere from six points in space. To facilitate the comparison of data, half of the Double Star payload is made of spare or duplicates of the Cluster instruments; the other half is made of Chinese instruments. The science operations are coordinated by the Chinese DSP Scientific Operations Centre (DSOC) in Beijing and the European Payload Operations Service (EPOS) at RAL, UK. The spacecraft and ground segment operations are performed by the DSP Operations and Management Centre (DOMC) and DSOC in China, using three ground station, in Beijing, Shanghai and Villafranca.