intra annual variation of wave number 4 structure of vertical e b drifts in the equatorial ionosphere seen from rocsat 1 1 this paper studies the intra annual variation of the wave number 4 structure in the equatorial vertical e b drifts at high solar flux level based on of the rocsat 1 observations during the interval from 1999 to 2004 it is found that the daytime longitudinal structure is significant in northern summer and early autumn but weak in northern winter this is consistent with the intra annual variations of the tidal mode de3 at night the intra annual variation of the wave number 4 structure shows some differences from that in daytime which may relate to different dynamo mechanisms operating in different local time we also found that the wave number 4 structure mainly shifts eastward during daytime in most of months which is coincident with the eastward propagation of the de3 tide however it is largely disturbed near sunrise and sunset we attribute this disturbance as the jumping of the main dynamo region between e and f layers as well as the different dynamo mechanisms in different dynamo regions

longitudinal variations in the f region ionosphere and the topside ionosphere plasmasphere observations and model simulations 1 constellation observing system for meteorology ionosphere and climate cosmic observations of the total electron content tec above and below 800 km are used to study the local time and seasonal variation of longitude structures in both the f region ionosphere as well as the topside ionosphere and plasmasphere the cosmic observations reveal the presence of distinct longitude variations in the topside ionosphere plasmasphere tec and these further exhibit a seasonal and local time dependence the predominant feature observed at all local times in the topside ionosphere plasmasphere tec is a substantial maximum minimum during northern hemisphere winter summer around 300 360 geographic longitude around equinox at a fixed local time a wave 4 variation in longitude prevails in the daytime f region tec as well as the topside ionosphere plasmasphere tec the wave 4 variation in longitude persists into the nighttime in the f region however the nighttime topside ionosphere plasmasphere tec exhibits two maxima in longitude the cosmic observations clearly reveal the presence of substantial longitude variations in the f region and topside ionosphere plasmasphere and to elucidate the source of the longitude variations results are presented based on the coupling between the global ionosphere plasmasphere model and the thermosphere ionosphere electrodynamics general circulation model the model simulations demonstrate that the orientation of the geomagnetic field plays a fundamental role in generating significant longitude variations in the topside ionosphere plasmasphere but does not considerably influence longitude variations in the f region ionosphere the model results further confirm that nonmigrating tides are the primary mechanism for generating longitude variations in the f region ionosphere the coupled model additionally demonstrates that nonmigrating tides are also of considerable importance for the generation of longitude variations in the topside ionosphere plasmasphere tec

satellite radar interferometry 1993 1999 suggests deep accumulation of magma near the crust mantle boundary at the krafla volcanic system iceland 1 deep magma accumulation near the crust mantle boundary 21 km depth at the krafla volcanic system is suggested from insar observations a best fit model derived from four interferograms covering 1993 1999 comprises an opening dike representing plate spreading and post rifting deformation and two mogi sources a mogi source deflating at a rate of 0 3 106 m3 yr coincides with the shallow krafla magma chamber while a deeper inflating mogi source further north at 21 km depth inflates at a rate of 26 106 m3 yr the inflating source is at or near the crust mantle boundary as identified by seismic studies and is interpreted as accumulating magma

3 d surface deformation of the 2000 usu eruption measured by matching of sar images a subpixel level offset estimation technique was applied to sar synthetic aperture radar images of usu volcano japan using radarsat sar amplitude images acquired from ascending and descending orbits we generated a map of three dimensional displacement vectors showing ground deformation associated with criptdome formation in april 2000 moreover displacement velocities and volume changes were estimated from april 3 29 inflation was observed with vertical and horizontal displacements each exceeding 20m during the period of major activity from april 3 5 uplift and n s spreading velocities reached 3 3m day and 2 7m day respectively while volume change was 3 4 106 m day although this technique is less precise than other methods and is not very sensitive to local deformations it provides several key advantages including 1 personnel are not required to enter hazardous areas 2 it provides wide spatial coverage and 3 it does not depend on coherence making it more widely applicable than insar

recent advances in sar interferometry time series analysis for measuring crustal deformation abstract synthetic aperture radar sar interferometry is a technique that permits remote detection of deformation at the earth s surface and has been used extensively to measure displacements associated with earthquakes volcanic activity and many other crustal deformation phenomena analysis of a time series of sar images extends the area where interferometry can be successfully applied and also allows detection of smaller displacements through the reduction of error sources here we review recent advances in time series sar interferometry methods that further improve accuracy this is particularly important when constraining displacements due to processes with low strain rates such as interseismic deformation we include examples of improved algorithms applied to image deformation associated with the 2010 eruption of eyjafjallajokull volcano in iceland slow slip on the guerrero subduction zone in mexico and tectonic deformation in western anatolia turkey

the effects of topography on magma chamber deformation models application to mt etna and radar interferometry we have used a three dimensional elastic finite element model to examine the effects of topography on the surface deformation predicted by models of magma chamber deflation we used the topography of mt etna to control the geometry of our model and compared the finite element results to those predicted by an analytical solution for a pressurized sphere in an elastic half space topography has a significant effect on the predicted surface deformation for both displacement profiles and synthetic interferograms not only are the predicted displacement magnitudes significantly different but also the map view patterns of displacement it is possible to match the predicted displacement magnitudes fairly well by adjusting the elevation of a reference surface however the horizontal pattern of deformation is still significantly different thus inversions based on constant elevation reference surfaces may not properly estimate the horizontal position of a magma chamber we have investigated an approach where the elevation of the reference surface varies for each computation point corresponding to topography for vertical displacements and tilts this method provides a good fit to the finite element results and thus may form the basis for an inversion scheme for radial displacements a constant reference elevation provides a better fit to the numerical results

longitudinal variation of the e region electric fields caused by atmospheric tides 1 polarization electric fields created by the e and f region dynamos cause the uplift of f region plasma the subsequent redistribution of that plasma along the magnetic field lines creates the equatorial ionospheric anomaly eia observations of the post sunset eia made by the image and timed satellites are compared here with champ orsted and sac c observations of the noontime equatorial electrojet eej during magnetically quiet periods around equinox the eia and eej show a remarkably similar four peaked wave like longitudinal variation its structure is consistent with the longitudinal variation in the strength of diurnal tides that drive the e region dynamo this indicates a strong vertical coupling between the ionosphere and troposphere because the four peaked tidal structure is driven by tropospheric weather furthermore the dayside ionospheric conditions are found to perform the global scale longitudinal structure of the post sunset ionosphere at low latitudes

pressure sources versus surface loads analyzing volcano deformation signal composition with an application to hekla volcano iceland the load of lava emplaced over periods of decades to centuries induces a gradual viscous response of the earth resulting in measurable deformation this effect should be considered in source model inversions for volcanic areas with large lava production and flow emplacement in small centralized regions if deformation data remain uncorrected constructive load and pressure source interference may result in an overestimate of depth and volume of a magma reservoir whereas destructive signal interference may cause these values to be underestimated in both cases the source geometry preference could be biased the ratio of horizontal and vertical displacements aids the identification of composite signals we provide a method to quantify and remove the lava load deformation signals using deformation at hekla volcano iceland as an example

thermal and mechanical aspects of magma emplacement in giant dike swarms we consider the thermal history and dynamics of magma emplacement in giant feeder dikes associated with continental flood basalts for driving pressure gradients inferred for giant dike swarms thicknesses of 10 m would enable dikes to transport magma laterally over the distances observed in the field up to thousands of kilometers without suffering thermal lock up using time dependent numerical solutions for the thermal evolution of a dike channel under laminar and turbulent flow conditions in the presence of phase transitions we investigate the possibility that the observed dike thicknesses of the order of 100 m result from thermal erosion of the country rocks during dike emplacement this implies that the observed range of dike widths in giant dike swarms may reflect variations in the source volume and not the excess magma pressure it is found that the total volume of intruded magma required to produce an order of magnitude increase in dike width via wall rock melting broadly agrees with the estimated volumes of individual flows in continental flood basalts the presence of chilled margins and apparently low crustal contamination characteristics of some giant dikes may be consistent with turbulent magma flow and extensive melt back during dike emplacement in this case measurements of the anisotropy of magnetic susceptibility most likely indicate magma flow directions during the final stages of dike intrusion shear stresses generated at the dike wall when the dike starts to freeze strongly decrease with increasing dike width which implies that thicker dikes may have less tendency to produce consistent fabric alignment our results suggest that if the dike was propagating downslope off a plume related topographic swell the mechanism responsible for flow termination could possibly have been related to underpressurization and collapse implosion of the shallow magma plumbing system feeding the intrusion radial dikes that erupted at the periphery of the topographic uplift might have increased rather than decreased extensional stresses in the crust within the topographic uplift upon their solidification

magma prospecting in usu volcano hokkaido japan using magnetotelluric soundings abstract we carried out magnetotelluric mt soundings across usu volcano hokkaido japan which has been active since 1663 the objective was to image an intrusion expected below the formation of 180m high cryptodomes formed during the 1977 78 eruption a ne sw two dimensional resistivity model has been obtained from the inversion in the frequency range from 0 01 to 10 000 hz the major features of the resistivity section are as follows 1 a 50 m thick surficial resistive 1000 10 000 m layer corresponding to the lava layer 2 a relatively conductive 10 1000 m layer from the surface to 200 m depth corresponding to quaternary sedimentary and volcanic rocks 3 beneath the quaternary formations a thick 2 4 km conductive 1 500 m layer of altered tertiary volcanics distributed widely in the volcanic edifice 4 a resistive block 500 1 000 m in the tertiary layer from 200 to 400 m in depth beneath the summit crater forming a striking contrast to the rest of the conductive tertiary layer and probably indicating a cooling intrusion at shallow depth 5 pre tertiary formations consisting of a high resistivity 1000 10 000 m layer overlying a conductive layer with the top of the pre tertiary becoming shallow to the northeast and 6 no deep conductive anomalies corresponding to a magma chamber inferred from petrological studies

wavenumber 4 patterns of the total electron content over the low latitude ionosphere 1 the global ionospheric maps gims produced by jpl are used to investigate the longitudinal structure of the low latitude ionosphere as a proxy of the ionization parameter at low latitudes the latitudinally integrated total electron content itec is first extracted from low latitude gims and then fourier filtered to obtain the wavenumber 4 components we then study in detail the diurnal seasonal and solar cycle variations of the wave patterns it is found that the wavenumber 4 patterns are intense and well developed in boreal summer and early boreal autumn but quite weak in boreal winter this seasonal variation is consistent with that of the zonal wind of the non migrating tide mode de3 we also found that the wavenumber 4 patterns shift eastward with a shifting speed that is smaller in daytime than at night this is attributed to the contribution of both the eastward propagation of de3 in e region and the zonal e b ion drifts in f region our results support the suggestion that the longitudinal wavenumber 4 structure of the low latitude ionosphere should be originated from the non migrating tide mode de3

connections between deep tropical clouds and the earth s ionosphere 1 we report on a series of simulations with the national center for atmospheric research ncar thermosphere ionosphere mesosphere electrodynamics general circulation model time gcm which were designed to replicate and facilitate the interpretation of the longitudinal structure discovered in image satellite airglow observations of the equatorial ionization anomaly eia at the far ultraviolet fuv 135 6 nm wavelength during march april 2002 equinox our time gcm results indicate that the four peaked longitudinal variation in the eia observed by image fuv near 20 00 local solar time can be explained by the effects of an eastward propagating zonal wavenumber 3 diurnal tide de3 that is excited by latent heat release associated with raindrop formation in the tropical troposphere

inter eruptive volcanism at usu volcano micro earthquakes and dome subsidence abstract post eruptive crustal activity after the 2000 eruption of usu volcano was investigated by seismic and geodetic field observations remarkable features of the magmatic eruptions that occur almost every 30 years include lava dome formation and strong precursory earthquakes on the other hand rapid dome subsidence was observed by electronic distance meter edm measurement after the 1977 1982 summit eruption since the 2000 eruption seismic activity at a shallow part under the summit crater has remained at a high level relative to that after the 1977 1982 eruption although eruption occurred at the western foot of the volcano during the 2000 eruption to reveal the shallow crustal activity in the inter eruptive period around the summit area seismicity and crustal deformation have been investigated since 2006 dense temporary seismic observations and hypocenter relocation analysis using a three dimensional velocity structure model revealed that the focal area is localized along the u shaped fault that developed in the dome forming stage of the 1977 1982 eruption three major focal clusters are distributed on the southwestern side of usu shinzan cryptodome which was built up during the 1977 1982 eruption for the seven major events with magnitudes larger than 1 the focal mechanism was a large dip slip component which suggests the subsidence of usu shinzan cryptodome interferomatetric satellite aperture radar insar image analysis and repeated gps measurements revealed subsidence of the summit dome which is almost centered at the usu shinzan cryptodome the area of rapid deformation is restricted to a small area around the summit crater the estimated rate of dome subsidence relative to the crater floor is about 3 cm year these results strongly suggest that subsidence of usu shinzan is associated with the small earthquakes along the u shaped fault that surrounds the cryptodome according to prior seismic and geodetic studies it is thought that most of the magma rising under the summit crater during the 2000 eruption stopped around a depth of 2 km below sea level which is sufficiently deep relative to the focal area of the present seismicity a part of the magma intruded under the western foot and contributed to the 2000 eruption we conclude that the 2000 eruption scarcely affected the shallow crustal activity under the summit crater and that usu shinzan cryptodome is continuing to subside just as it was before the 2000 eruption the shallow volcanic earthquakes that began increasing from 1995 are closely related to the successive subsidence of the summit domes temporal change in fumarole temperature suggests a relationship between the shallow earthquakes and cooling of the magma that intruded under usu shinzan during the 1977 1982 eruption

longitudinal variations in the equatorial vertical drift in the topside ionosphere 1 the vertical ion drift is important for understanding and modeling the electrodynamics at low latitudes measurements from the ion drift meter on the defense meteorological satellite program dmsp f15 are used to examine longitudinal variations in the vertical ion drift at the dip equator in the topside ionosphere local time was restricted to 0930 and the data were organized by month for 2001 and 2002 two features were found contributing to the longitudinal variations in the electrodynamics meridional winds contribute to the equatorial vertical ion drift at the 830 km magnetic apex due to their dynamo action at the foot points of the magnetic field lines in the f region at magnetic latitudes near 15 electric fields producing a downward perturbation drift at 0930 are produced by hemispheric differences in the dynamo current due primarily to the different orientation of the magnetic meridian relative to the terminator this produces the seasonally dependent variation as a function of longitude that is observed a wavenumber 4 longitudinal variation also appears to be present throughout the year but is more influential during equinox conditions this variation also shows a seasonal cycle shifting east during northern summer and west during northern winter further analysis would be required to isolate the characteristics of a wavenumber 4 driver from the wavenumber 4 component of the fourier series used here to fit the data

field aligned neutral wind bias correction scheme for global ionospheric modeling at midlatitudes by assimilating formosat 3 cosmic hmf2 data under geomagnetically quiet conditions this study demonstrates the usage of a data assimilation procedure which ingests the formosat 3 cosmic f3 c hmf2 observations to correct the model wind biases to enhance the capability of the new global ionosphere plasmasphere electrodynamics ipe model under geomagnetically quiet conditions the ipe model is built upon the field line interhemispheric plasma model with a realistic geomagnetic field model and empirical model drivers the hmf2 observed by the f3 c radio occultation technique is utilized to adjust global thermospheric field aligned neutral winds i e a component of the thermospheric neutral wind parallel to the magnetic field at midlatitudes according to a linear relationship between time differentials of the field aligned wind and hmf2 the adjusted winds are further applied to drive the ipe model the comparison of the modeled electron density with the observations of f3 c and ground based gps receivers at the 2012 march equinox suggests that the modeled electron density can be significantly improved in the midlatitude regions of the southern hemisphere if the wind correction scheme is applied moreover the f3 c observation the ipe model and the wind bias correction scheme are applied to study the 2012 southern hemisphere midlatitude summer nighttime anomaly southern msna weddell sea anomaly wsa event at december solstice for examining the role of the neutral winds in controlling the longitudinal variation of the southern msna wsa behavior with the help of the wind bias correction scheme the ipe model better tracks the f3 c observed eastward movement of the southern msna wsa feature the apparent eastward movement of the southern msna wsa features in the local time coordinate is primarily caused by the longitudinal variation in the declination angle of the geomagnetic field that controls the field aligned projection of both geographic meridional and zonal components of the neutral wind both the ipe simulations and the f3 c observations show the significant longitudinal variation in the speed of the eastward movement of the southern msna wsa

temperature dependent viscoelastic modeling of ground deformation application to etna volcano during the 1993 1997 inflation period abstract we used the finite element method fem for modeling time dependent ground deformation due to volcanic pressure sources embedded in a viscoelastic medium especially in volcanic areas the presence of heterogeneous materials and high temperatures produce a lower effective viscosity of the earth s crust that calls for considering the thermal regime of crustal volume surrounding the magmatic sources we propose a thermo mechanical numerical model for evaluating the temperature dependency of the viscoelastic solution both temperature distributions and ground deformation are evaluated by solving an axi symmetric problem to estimate the effects of thermo viscoelastic response of the medium the thermo mechanical model permits to evidence that viscoelastic relaxation is responsible for significant time dependent variations in long term deformation these effects may be relevant for the interpretation and quantitative assessments of the pressure changes within magmatic sources with this in mind we reviewed the ground deformation observed on etna volcano during the 1993 1997 inflation period by setting up a fully 3d temperature dependent viscoelastic model since 1993 different geodetic measurements edm gps sar and leveling data identified an inflationary phase characterized by a uniform and continuous expansion of the overall volcano edifice that was not perturbed by eruptive activity the numerical model including significant viscoelastic material and reduced crustal rigidity around the magmatic source enables to produce deformation comparable with those obtained from elastic model requiring a significantly lower pressure for a purely elastic model with the same geometry and rigidity the pressure change necessary to describe the 1993 through 1997 inflation is around 320 mpa whereas for the viscoelastic model a pressure increase of about 200 mpa is required

longitudinal variation in global navigation satellite systems tec and topside ion density over south american sector associated with the four peaked wave structures 1 recent observations of the low latitude ionospheric electron density revealed a four peaked longitudinal structure in the equatorial ionization anomaly when plotted at a constant local time frame it was proposed that neutral wind driven e region dynamo electric fields due to nonmigrating tidal modes are responsible for this pattern we examine the four peaked structure in the observed topside ion density and its manifestation as longitudinal structures in total electron content tec over south america the strong longitudinal variation in tec characterized by larger value over brazilian eastern longitude sector as compared to that over the peruvian western longitude is modeled using the sheffield university plasmasphere ionosphere model supim aiming to identify the control factors responsible for the longitude variation we found that the supim runs using as input the existing standard models of vertical drift and thermospheric winds do not explain the tec longitudinal structure realistic values of these control parameters were generated based on the strong vertical drift longitudinal variation as determined from magnetometer and digisonde data and appropriately adjusted winds horizontal wind model these realistic vertical drifts together with the modified thermospheric wind when used as input to the supim are found to satisfactorily explain the longitudinal differences in the tec and topside ion density ni over south america the study shows that the tec in the whole latitude distribution is larger over the east coast than over the west coast of south america and that the vertical drift and thermospheirc winds control the longitudinal four wave structure in the tec and ni

seismological significance of the 1977 1978 eruptions and the magma intrusion process of usu volcano hokkaido abstract an earthquake swarm and the major pumice eruptions in august 1977 which followed marked the start of the dacitic doming activity of usu volcano in southwestern hokkaido japan the sequence of magma intrusion processes was investigated in detail by means of seismological and other geophysical data the distribution of the abundant hypocenters shows clearly an earthquake free zone beneath the summit crater the hypocenters migrated in a manner consistent with the development of the observed asymmetrical surface deformations considered due to magma intrusion into this earthquake free zone the earthquake mechanism solutions are mostly of dip slip type and are interpreted in terms of the doming deformations the existence of earthquake families earthquakes with similar waveforms is the main cause of the peculiar occurrence of earthquakes in space time and magnitude the concept of scattered barriers of different sizes and strengths can explain well the distinct characteristics of the occurrence of the swarm and the observed episodic deformations

global ionospheric response to nonmigrating de3 and de2 tides forced from below 1 in this paper we present the global spatial structure and seasonal variability of the cosmic electron density response to the forced from below de3 and de2 tides during the period january 2008 to march 2009 the cosmic electron density at fixed altitudes and saber temperatures were utilized in order to define the ionospheric de3 and de2 tidal response to the de3 and de2 temperature tides coming from below the tidal waves from both data sets have been extracted by the same data analysis method the latitude structure of the ionospheric response for heights up to 450 500 km is distributed on both sides of the dip equator at about 30 modified dip latitude above 500 km the response is approximately confined over the equator two altitude regions of enhanced ionospheric response are found an upper level response above 300 km and a bottom level one below 250 km the two regions are separated by a narrow altitude zone with no tidal response the different phase structure of the ionospheric response in both altitude regions suggests that 1 the upper level response is mainly due to the de3 de2 modulated vertical plasma drift and 2 the bottom level response is complex and in all likelihood is caused by more than one mechanism

ground surface deformation patterns magma supply and magma storage at okmok volcano alaska from insar analysis 1 intereruption deformation 1997 2008 eruption magma storage had increased by 3 7 5 2 1 0 7 m 3 or 85 100 of the 1997 eruption volume we propose that the supply rate decreased in response to the diminishing pressure gradient between the shallow storage zone and a deeper magma source region eventuallytheeffectsofcontinuingmagmasupplyandvesiculationofstoredmagmacaused acriticalpressurethresholdtobeexceeded triggeringthe2008eruption asimilarpatternof initially rapid inflation followed by oscillatory but generally slowing inflation was observed prior to the 1997 eruption in both cases withdrawal of magma during the eruptions depressurized the shallow storage zone causing significant volcano wide subsidence and initiating a new intereruption deformation cycle

longitudinal variation of f region electron density and thermospheric zonal wind caused by atmospheric tides 1 simultaneous observations of the electron density and the zonal wind obtained by the champ satellite at 400 km are used to study systematic longitudinal variations the time period selected is august september 2004 allowing observations at pre noon and post sunset hours the equatorial ionization anomaly eia and the zonal delta wind deviation from zonal average show a persistent and dominant 4 peaked longitudinal variation we interpret this structure as caused by the wavenumber 3 nonmigrating diurnal tide de3 the eia and the zonal delta wind exhibit extrema at about the same longitudes but while the intensifications of the eia and the delta wind are in phase during the evening hours they are out of phase in the morning possible coupling mechanisms are investigated

towards an improved seismic imaging technique for crustal structures the lithoprobe sudbury experiment under the canadian lithoprobe program conventional low 10 55 hz and high frequency 30 140 hz vibroseis reflection surveys were conducted across the sudbury structure the main objective of the study was to evaluate the performance of seismic exploration techniques in a complex mainly crystalline geological setting the sudbury experiment demonstrated that high input frequencies can be preserved through appropriate acquisition and processing procedures consequently the high frequency seismic data proved capable of imaging complex shallow crustal structures not seen by the conventional low frequency seismic survey in crystalline environments improved high frequency seismic exploration technology will provide a better link between seismic images and surface geology

global response of the ionosphere to atmospheric tides forced from below comparison between cosmic measurements and simulations by atmosphere ionosphere coupled model gaia 1 this paper for the first time presents a detailed comparison between simulated and observed global electron density responses to different atmospheric tides forced from below the recently developed earth s whole atmospheric model from the troposphere to the ionosphere called gaia has been used for the simulation of the electron density tidal responses they have been compared with the extracted from the cosmic electron density data tidal responses for the period of time october 2007 to march 2009 particular attention has been paid to the nonmigrating de3 de2 and migrating dw1 sw2 and tw3 electron density responses the gaia model reproduced quite well the cosmic de3 de2 responses both simulations and observations revealed three altitude regions of enhanced electron density responses 1 an upper level response above 300 km height apparently shaped mainly by the fountain effect 2 a response located near altitudes of 200 270 km and 3 a lower thermospheric response situated near 120 150 km height a possible mechanism is suggested for explaining the two lower level responses for the first time the gaia model simulations supported the observational evidence found in the cosmic measurements that the ionospheric wn4 wn3 longitude structure is not generated only by the de3 de2 tide as it has been often assumed as regards the comparison of the migrating dw1 sw2 and tw3 responses the obtained results clearly demonstrate that the gaia model reproduce very well of the sw2 and tw3 cosmic electron density responses the only main discrepancy is seen in the migrating dw1 response the observation does not support the splitting of the simulated response at both sides of the equator this is due mainly to the difference between the saber and gaia sw2 tide in the lower thermosphere as it turned out that the dw1 electron density response strongly depends on the mean features of the lower thermospheric sw2 tide

structure and origins of the weddell sea anomaly from tidal and planetary wave signatures in formosat 3 cosmic observations and gaia gcm simulations the weddell sea anomaly wsa is a recurrent feature of the austral summer midlatitude ionosphere where electron densities are observed to maximize during the local nighttime in this study tidal decomposition is applied to formosat 3 formosa satellite constellation observing system for meteorology ionosphere and climate cosmic total electron content tec and electron density observations between 2007 and 2012 to quantify the components dominating local time and spatial variation in the wsa region our results present some of the first three dimensional spaceborne analyses of the wsa from a tidal perspective over multiple years we find that the features of the wsa can be reconstructed as the result of superposition between the dominant diurnal standing d0 eastward wave number 1 de1 westward wave number 2 dw2 and stationary planetary wave 1 spw1 components in tecs producing the characteristic midnight wsa peak the d0 de1 dw2 and spw1 components are found to be an interannually recurring feature of the southern midlatitude to high latitude ionosphere during the summer manifesting as enhancements in electron density around 300 km altitude of the summer middle to high magnetic latitudes the phases of the aforementioned nonmigrating diurnal signatures in electron density in this region are near evanescent suggesting in situ generation rather than upward propagation from below however the spw1 signature shows some signs of an eastward tilt with altitude suggesting possible downward propagation the relation of these components to possible generation via in situ photoionization or plasma transport along magnetic field lines is also discussed using results from the ground to topside model of atmosphere and ionosphere for aeronomy gaia general circulation model gcm connecting the tidal interpretation of the wsa to previously examined generation mechanisms

simulated equinoctial asymmetry of the ionospheric vertical plasma drifts 1 this paper studies the influence of the lower thermospheric tidal winds below 105 km on the equinoctial asymmetry of the equatorial vertical e b plasma drifts v using theoretical ionospheric dynamo model ii of the institute of geology and geophysics chinese academy of sciences tidm iggcas ii and tidal winds below 105 km from thermosphere ionosphere mesosphere energetics dynamics satellite doppler interferometer tidi observations although a series of other nonmigrating tides also affect the v asymmetry the simulated equinoctial asymmetry in v are mainly driven by the migrating diurnal tide dw1 migrating semidiurnal tide sw2 de3 and dw2 nonmigrating tides the asymmetry in daytime v varies with local time and longitude and mainly shows three features first the simulated daytime v during the march equinox is larger than that during the september equinox in most of longitudinal sectors this asymmetry is mainly driven by the semiannual oscillation sao of the migrating diurnal tide in the tropical mesosphere lower thermosphere mlt region and the equinoctial asymmetry of the migrating semidiurnal tide also plays an important role in the generation of this asymmetry second the daytime v asymmetry in the eastern hemisphere is more significant than that in the western hemisphere our simulation suggests that the longitudinal variations of the geomagnetic fields and dw2 tides play important roles in the generation of this hemisphere difference third there is an obvious wave number 4 longitudinal structure in the v asymmetry our simulation suggests that this wave number 4 structure is mainly driven by the equinoctial asymmetry of the de3 tide

longitudinal structure of the equatorial anomaly in the nighttime ionosphere observed by image fuv 1 the far ultraviolet imager fuv on board the image satellite provides an instantaneous global view of the oi 135 6 nm nightglow with 2 min time resolution because the oi 135 6 nm emission from the nighttime ionosphere is determined by the line of sight integrated plasma density the nightglow images are useful for studying the nighttime low latitude ionosphere globally with the image fuv 135 6 nm observations from march to june 2002 we have examined the global characteristics of the nighttime equatorial anomaly ea by constructing a constant local time map lt map in which pixels within an assigned local time range are extracted from the image fuv nightglow images obtained over an observation period of 3 days or more and are put together to compose a global distribution map of emission intensities at that local time these lt maps show that the development of the ea has a significant longitudinal structure in which peaks and dips of the crest emission intensity and the crest latitude have about 90 longitudinal separation in the longitude range from 0 to 250 although there is not enough data over the american sector this result suggests that the ea longitudinal structure has a prominent zonal component of the wave number 4 the observed longitudinal structure of the nighttime ea could not be fully explained by factors such as the empirical electric field and neutral wind models the geomagnetic declination angle or the displacement of the geomagnetic equator from the geographic equator to explain the observed longitudinal structure of the ea in particular the wave number 4 feature we may need to consider other forcing for example nonmigrating tide originated from the lower atmosphere

characterization of open and closed volcanic systems in indonesia and mexico using insar time series 1 we use 2007 2011 advanced land observing satellite alos data to perform an arc wide interferometric synthetic aperture radar insar time series survey of the trans mexican volcanic belt tmvb and to study time dependent ground deformation of four indonesian volcanoes selected following the 2007 2009 study of chaussard and amelung 2012 our objectives are to examine whether arc volcanoes exhibit long term edifice wide cyclic deformation patterns that can be used to characterize open and closed volcanic systems and to better constrain in which cases precursory inflation is expected we reveal deformation cycles at both regularly active and previously inactive indonesian volcanoes but we do not detect deformation in the tmvb reflecting a lower activity level we identify three types of relationships between deformation and activity inflation prior to eruption and associated with or followed by deflation kerinci and sinabung inflation without eruption and followed by slow deflation agung and eruption without precursory deformation merapi colima and popocatepetl at merapi no significant deformation is detected even during eruption the first two cases correspond to closed volcanic systems and suggest that the traditional model of magmatic systems and eruptive cycles do apply to andesitic volcanoes i e inflation and deflation episodes associated with magma accumulation or volatile exsolution in a crustal reservoir followed by eruptions or in situ cooling in contrast the last case corresponds to open volcanic systems where no significant pressurization of the magmatic reservoirs is taking place prior to eruptions and thus no long term edifice wide ground deformation can be detected we discuss these results in terms of insar s potential for forecasting volcanic unrest

radar interferogram filtering for geophysical applications the use of sar interferometry is often impeded by decorrelation from thermal noise temporal change and baseline geometry power spectra of interferograms are typically the sum of a narrow band component combined with broad band noise we describe a new adaptive filtering algorithm that dramatically lowers phase noise improving both measurement accuracy and phase unwrapping while demonstrating graceful degradation in regions of pure noise the performance of the filter is demonstrated with sar data from the ers satellites over the jakobshavns glacier of greenland

an empirical model of the occurrence of an additional layer in the ionosphere from the occultation technique preliminary results about 8 year electron density profile edp data from the cosmic formosat 3 satellites radio occultation technique were used to investigate the additional stratification of the f2 the so called f3 layer layer over the equatorial and low latitude ionosphere on a global scale for both the bottomside and topside ionosphere the f3 layer was recognized through the altitude differential profile featured by two maxima existing from the selected edp profile there were 37 000 bottomside and 25 000 topside cases of f3 layer selected out of 1 27 million occultation events at equatorial and low latitude areas during the period of april 2006 to august 2014 the statistical results for the bottomside ionosphere resemble that reported in zhao et al 2011a while in the topside the highest occurrence of f3 layer shows a 3 4 h delay depending on the altitude range of the stratification the magnetic latitude distribution shows different dependence with a tendency to form a single crest toward high altitude also the seasonal variation is weaker in the topside ionosphere compared to the bottomside one especially in the high altitude then we build up an empirical model of the f3 layer occurrence using the bottomside statistics based on empirical orthogonal function eof decomposition as it gets the inherent characters inside the data set and converges quickly the model well grasps the main features of the f3 occurrence e g the f3 occurrence s sensitivity on the magnetic latitude further in order to accommodate the ground observation a corrected factor was introduced as f3 layer is an important phenomenon in the low latitude ionosphere we have made an attempt to describe its feature with a consecutive function although future work needs to be done for an overall expression of this structure

strong evidence for the tidal control on the longitudinal structure of the ionospheric f region this paper presents for the first time the global latitude structure and seasonal variability of the ionospheric response to the forced from below de3 and de2 tides during the period of time january 2008 march 2009 the cosmic hmf2 and saber temperature data have been utilized in order to define the ionospheric de3 and de2 tidal response to the de3 and de2 temperature tides propagating from below the cosmic de3 and de2 hmf2 tidal oscillations are derived by the same method as the tides seen the saber temperatures it has been shown that the longitude wave 4 and wave 3 hmf2 structures observed respectively in september and may 2008 are forced mainly by de3 wave 4 and de2 wave 3 temperature tides coming from below the longitude wave 3 hmf2 structure observed in january 2008 however is forced by the combined action of the de2 temperature tide coming from below and the spw3 probably generated in situ

localized deformation at miyakejima volcano based on jers 1 radar interferometry 1992 1998 1 stacked radar interferograms at miyakejima volcano japan between 1992 and 1998 showed two localized significantly deforming areas with a magnitude of 4 6 mm yr in the radar line of sight one area is close to the 1983 eruption vent and using a simple closed analytical formulation the deformation is interpreted as due to a thermoelastic contraction of a formerly intruded magma the other one detected in the previous caldera is explained by a depressurization source whose depth 500 m coincides with that of a low resistivity zone interpreted as a hydrothermal reservoir also our computed co2 flux is consistent with in situ measurement data the reservoir volume is significantly less than the collapsed volume in 2000 and its depth is much shallower than the void detected prior to the collapse hence the depressurization would not directly induce the caldera collapse in 2000

quiet time equatorial f region vertical plasma drift model derived from rocsat 1 observations 1 we have used five years of measurements on board the rocsat 1 satellite to develop a detailed quiet time global empirical model for equatorial f region vertical plasma drifts this model describes the local time seasonal and longitudinal dependence of the vertical drifts for an altitude of 600 km under moderate and high solar flux conditions the model results are in excellent agreement with measurements from the jicamarca radar and also from other ground based and in situ probes we show that the longitudinal dependence of the daytime and nighttime vertical drifts is much stronger than reported earlier especially during december and june solstice the late night downward drift velocities are larger in the eastern than in the western hemisphere at all seasons the morning and afternoon december solstice drifts have significantly different longitudinal dependence and the daytime upward drifts have strong wave number four signatures during equinox and june solstice the largest evening upward drifts occur during equinox and december solstice near the american sector the longitudinal variations of the evening prereversal velocity peaks during december and june solstice are anti correlated which further indicates the importance of conductivity effects on the electrodynamics of the equatorial ionosphere