global variations of thermospheric winds and temperatures caused by substorm energy injection two numerical simulations of the thermospheric response to magnetospheric energy injection have been performed using a zonally averaged time dependent model of neutral composition dynamics and energy budget the simulations are distinguished by the duration of the source the first simulation has an energy injection of 1 hour representative of substorm type forcing and the second one has a 12 hour energy injection representative of main storm type forcing they were performed under the condition of equinox at solar minimum in the first simulation large scale atmospheric gravity waves agws generated by the substorm energy via joule heating of ionospheric currents are clearly identified in the wind field in a meridional plane as well as in the temporal and spacial variations of the total energy density of air above about 130 km height these waves reach the equator after about 3 hours and propagate into the opposite hemisphere the horizontal propagation speed is close to the speed of sound for example roughly 440 m s at about 150 km altitude and 670 m s at about 260 km altitude snapshots of the wind system affected by the substorm energy injection show a four cell pattern between the poles above 260 km the cells have the opposite rotational direction to those below these small scale features in the wind system are indicative of the internal atmospheric gravity waves with the vertical phase propagation from a term analysis of the energy conservation equation it is identified that the dominant energy process associated with the propagation of agws is adiabatic compressional heating and or expansive cooling process it can be concluded that the energy oscillations at middle and low latitude are mainly produced by agws propagating from high latitude during the substorm the second simulation indicated that horizontal and vertical advections vertical heat conduction and infrared radiative cooling by nitric oxide are important in addition to adiabatic compressional heating and or expansive cooling it is suggested that short duration energy injection preferentially generates agws which dominate the energy oscillations at low latitudes through adiabatic heating and cooling long duration energy injection is more effective in generating a meridional circulation which transfers energy by both advective and adiabatic processes

ionospheric annual anomaly new insights to the physical mechanisms the ionospheric annual anomaly or nonseasonal anomaly of the ionosphere is characterized by globally increased ionization in december solstice than in june solstice though this phenomenon was reported several decades ago the causal mechanisms have not been fully understood till today in this paper the f2 layer peak electron density nmf2 data from formosa satellite 3 constellation observing system for meteorology ionosphere and climate radio occultation observations during the low solar activity year 2009 were systematically analyzed to investigate the physical mechanisms responsible for annual anomaly and its local time latitudinal and longitudinal variability it is found that the annual anomaly is primarily dominant at southern hemisphere at all local times with significant enhancements at equatorial ionization anomaly crest latitudes during noon to afternoon hours and at high latitudes during nighttimes the annual anomaly in northern hemisphere occurs with relatively smaller magnitudes and confined only to morning to early afternoon hours 08 14 lt this study brings out the important roles of effective neutral winds due to the geomagnetic field configuration and the offset between geomagnetic equator and subsolar point for the enhanced plasma density in the southern hemisphere during december that majorly contributes to the ionospheric annual anomaly these results provide new insights to the responsible mechanisms behind the ionospheric annual anomaly and its local time latitudinal and longitudinal variation

conjugate hemisphere ionospheric response to the st patrick s day storms of 2013 and 2015 in the 100 e longitude sector the effects of the st patrick s day geomagnetic storms of 2013 and 2015 in the equatorial and low latitude regions of both hemispheres in the 100 e longitude sector is investigated and compared with the response in the indian sector at 77 e the data from a chain of ionosondes and gps global navigation satellite systems receivers at magnetic conjugate locations in the 100 e sector have been used the perturbation in the equatorial zonal electric field due to the prompt penetration of the magnetospheric convective under shielded electric field and the over shielding electric field gives rise to rapid fluctuations in the f2 layer parameters the direction of imf bz and disturbance electric field perturbations in the sunset sunrise period is found to play a crucial role in deciding the extent of prereversal enhancement which in turn affect the irregularity formation equatorial spread f in the equatorial region the northward southward imf bz in the sunset period inhibited supported the irregularity formation in 2015 2013 in the 100 e sector large height increase hmf2 during sunrise produced short duration irregularities during both the storms the westward disturbance electric field on 18 march inhibited the equatorial ionization anomaly causing negative positive storm effect in low latitude equatorial region the negative effect was amplified in low midlatitude by disturbed thermospheric composition which produced severe density total electron content depletion the longitudinal and hemispheric asymmetry of storm response is observed and attributed to electrodynamic and thermospheric differences

observations at terrestrial impact structures their utility in constraining crater formation hypervelocity impact involves the near instantaneous transfer of considerable energy from the impactor to a spatially limited near surface volume of the target body local geology of the target area tends to be of secondary importance and the net result is that impacts of similar size on a given planetary body produce similar results this is the essence of the utility of observations at impact craters particularly terrestrial craters in constraining impact processes unfortunately there are few well documented results from systematic contemporaneous campaigns to characterize specific terrestrial impact structures with the full spectrum of geoscientific tools available at the time nevertheless observations of the terrestrial impact record have contributed substantially to fundamental properties of impact there is a beginning of convergence and mutual testing of observations at terrestrial impact structures and the results of modeling in particular from recent hydrocode models the terrestrial impact record provides few constraints on models of ejecta processes beyond a confirmation of the involvement of the local substrate in ejecta lithologies and shows that z models are at best first order approximations observational evidence to date suggests that the formation of interior rings is an extension of the structural uplift process that occurs at smaller complex impact structures there are however major observational gaps and cases e g vredefort where current observations and hydrocode models are apparently inconsistent it is perhaps time that the impact community as a whole considers documenting the existing observational and modeling knowledge gaps that are required to be filled to make the intellectual breakthroughs equivalent to those of the 1970s and 1980s which were fueled by observations at terrestrial impact structures filling these knowledge gaps would likely be centered on the later stages of formation of complex and ring structures and on ejecta

long duration penetration of the interplanetary electric field to the low latitude ionosphere during the main phase of magnetic storms 1 it is well known that the interplanetary electric field can penetrate to the low latitude ionosphere it is generally believed that the penetration of electric fields can last only for 30 min because of the shielding effect in the ring current in this paper we present the observations of the dayside ionospheric electric field enhancements at middle and low latitudes in association with reorientations of the interplanetary magnetic field imf in six cases the eastward electric field in the dayside equatorial ionosphere measured by the jicamarca incoherent scatter radar was enhanced for 2 3 hours after the imf turned southward and remained continuously southward in one case the eastward electric field in the dayside midlatitude ionosphere measured by the millstone hill incoherent scatter radar was continuously enhanced for 10 hours during southward imf since millstone hill is close to the equatorward boundary of the auroral zone during magnetic storms the penetration electric field there may be different from that at the equatorial ionosphere the most striking feature of the measurements is that the enhancements of the ionospheric electric field can last for many hours without significant decay the electric field enhancements in the middle and low latitude ionosphere are closely related to magnetic activity and occur during the main phase of magnetic storms the observations show that the interplanetary electric field can continuously penetrate to the low latitude ionosphere without shielding for many hours as long as the strengthening of the magnetic activity is going on under storm conditions

duskside enhancement of equatorial zonal electric field response to convection electric fields during the st patrick s day storm on 17 march 2015 the equatorial zonal electric field responses to prompt penetration of eastward convection electric fields ppef were compared at closely spaced longitudinal intervals at dusk to premidnight sectors during the intense geomagnetic storm of 17 march 2015 at dusk sector indian longitudes a rapid uplift of equatorial f layer to 550 km and development of intense equatorial plasma bubbles epbs were observed these epbs were found to extend up to 27 13 n and 25 98 s magnetic dip latitudes indicating their altitude development to 1670 km at apex in contrast at few degrees east in the premidnight sector thailand indonesian longitudes no significant height rise and or epb activity has been observed the eastward electric field perturbations due to ppef are greatly dominated at dusk sector despite the existence of background westward ionospheric disturbance dynamo idd fields whereas they were mostly counter balanced by the idd fields in the premidnight sector in situ observations from swarm a and swarm c and communication navigation outage forecasting system satellites detected a large plasma density depletion near indian equatorial region due to large electrodynamic uplift of f layer to higher than satellite altitudes further this large uplift is found to confine to a narrow longitudinal sector centered on sunset terminator this study brings out the significantly enhanced equatorial zonal electric field in response to ppef that is uniquely confined to dusk sector the responsible mechanisms are discussed in terms of unique electrodynamic conditions prevailing at dusk sector in the presence of convection electric fields associated with the onset of a substorm under southward interplanetary magnetic field bz

the constitution and structure of the lunar interior the current state of understanding of the lunar interior is the sum of nearly four decades of work and a range of exploration programs spanning that same time period missions of the 1960s including the rangers surveyors and lunar orbiters as well as earth based telescopic studies laid the groundwork for the apollo program and provided a basic understanding of the surface its stratigraphy and chronology through a combination of remote sensing surface exploration and sample return the apollo missions provided a general picture of the lunar interior and spawned the concept of the lunar magma ocean in particular the discovery of anorthite clasts in the returned samples led to the view that a large portion of the moon was initially molten and that crystallization of this magma ocean gave rise to mafic cumulates that make up the mantle and plagioclase flotation cumulates that make up the crust smith et al 1970 wood et al 1970 this model is now generally accepted and is the framework that unifies our knowledge of the structure and composition of the moon the intention of this chapter is to review the major advances that have been made over the past decade regarding the constitution of the moon s interior much of this new knowledge is a direct result of data acquired from the successful clementine and lunar prospector missions as well as the analysis of new lunar meteorites as will be seen results from these studies have led to many fundamental amendments to the magma ocean model much of what we know from sample analyses has been previously summarized elsewhere and only their most important aspects will be discussed in this chapter the reader is referred to the relevant chapters in the books basaltic volcanism on the terrestrial planets basaltic volcanism study project 1981 the

a new technique for estimating the thickness of mare basalts in imbrium basin 1 the total volume of extrusive volcanism on the moon provides a basic thermal and geologic constraint and accurate volume assessments are contingent upon constraining lava flow depths here employing uv vis data from the clementine mission we estimate mare thickness values in the imbrium basin by analyzing ejecta from large 10 km diameter impact craters that penetrate or failed to penetrate through the mare mare thickness values are found to range from at least 2 km at the basin center to 1 5 2 0 km in the buried ring shelf annulus this corresponds to a basalt volume of 1 3 106 km3 almost a factor of two greater than the volume estimated from partially filled craters alone our results indicate that thickness measurements from penetrating craters combined with minimum estimates from partially filled and non penetrating craters provide a more complete picture of the spatial variation of basalt thickness values than could previously be obtained

lunar mare basalt flow units thicknesses determined from crater size frequency distributions accurate lava flow unit thicknesses estimates are necessary to place constraints on volcanic flux estimates we refine the technique of using the shape of crater size frequency distribution csfd curves to estimate the thickness of individual lunar mare flow units we find that a characteristic knee often observed in csfd curves is reasonably interpreted to represent the presence of two lava flow units separated in time and that the diameter at which this knee occurs is related to the thickness of the overlying flow unit examination of 58 curves with this characteristic knee in several lunar nearside basins oceanus procellarum imbrium tranquillitatis humorum cognitum nubium and insularum allowed us to identify flow units that have not been detected in low sun images we found that the range of flow unit thickness is 20 220 m and the average is 30 60 m this technique expands considerably the ability to assess lava flow unit thicknesses and volumes on the moon and planets

a simulation study of the equatorial ionospheric response to the october 2013 geomagnetic storm the ionospheric observation from ionosonde at sao luis 2 5 s 44 2 w 6 68 s dip latitude around the magnetic equator showed that the nighttime ionospheric f2 layer was uplifted by more than 150 km during the october 2013 geomagnetic storm the changes of the f2 peak height hmf2 at the magnetic equator were generally attributed to the variations of vertical drift associated with zonal electric fields in this paper the thermosphere ionosphere electrodynamics general circulation model tiegcm simulation results are utilized to explore the possible physical mechanisms responsible for the observed increase of hmf2 at sao luis the tiegcm generally reproduced the changes of f2 peak electron density nmf2 and its height hmf2 during the main and recovery phases of the october 2013 storm a series of controlled simulations revealed that storm time hmf2 changes at the magnetic equator are not purely associated with the changes of electric fields horizontal plasma transport due to meridional winds and thermospheric expansion also contributed significantly to the profound increase of nighttime hmf2 observed at sao luis on 2 october moreover the changes of meridional winds and neutral temperature in the equatorial region are associated with storm time travelling atmospheric disturbances originating from high latitudes

behavior of the f2 peak ionosphere over the south pacific at dusk during quiet summer conditions from cosmic data 1 the six satellite constellation observing system for meteorology ionosphere and climate cosmic mission makes routine ionospheric measurements over the entire globe using occultation techniques these observations have been used in this study to develop global scale climate maps of nmf2 and hmf2 during the southern northern summer winter enhanced electron densities that appear to be associated with the southern equatorial appleton anomaly are displaced far southward at dusk and within about an hour form the weddell sea anomaly coincidentally the height of the f2 peak increases on the northern boundary of this anomaly this height increase is also displaced southward as the enhanced electron densities are displaced southward suggesting that the electron density increases are associated with the f2 peak rising as well as being an interesting phenomenon in its own right this behavior may shed new light on the formation of the weddell sea anomaly no unambiguous explanation for this behavior can be determined from the data presently available but an examination of some possibilities suggests that an evening downward flux of plasma from the plasmasphere may be at least partly responsible for the phenomenon

mapping the feo and tio2 content of the lunar surface with multispectral imagery the derivation of quantitative elemental concentrations from multispectral imaging of the moon has long been a goal of lunar remote sensing concentration maps at the spatial resolutions available from the recent clementine mission would provide a revolutionary new tool for understanding the origin and evolution of the lunar crust lucey et al 1995 presented a method for extracting the concentration of fe from multispectral imaging of the moon this paper examines and quantifies important aspects ofthat technique left unexamined by lucey et al which had the potential to severely limit its utility these aspects include the effects of maturity grain size mineralogy shading due to topography and the presence of glass we also present a new algorithm for derivation of tio2 from multispectral imaging of both mare and highland units we find that both techniques are only weakly sensitive to maturity and that they have about 1 wt accuracy based on examination of the spectral properties and compositions of resolved lunar sampling stations presented by blewett et al 1997 we also discuss these findings in the context of two contrasting views of the effect of composition on lunar spectral properties presented by pieters and coworkers and hapke and coworkers we find the view of hapke and coworkers to be more consistent with our observations using a global mosaic of clementine multispectral data and these element derivation algorithms we find that the global modal abundance of feo is 4 5 wt 1 wt and the global modal abundance of tio2 is 0 45 wt 1 wt

effects of disturbed electric fields in the low latitude and equatorial ionosphere during the 2015 st patrick s day storm the 2015 st patrick s day geomagnetic storm with sym h value of 233 nt is an extreme space weather event in the current 24th solar cycle in this work we investigated the main mechanisms of the profound ionospheric disturbances over equatorial and low latitudes in the asian australian sector and the american sector during this super storm event the results reveal that the disturbed electric fields which comprise penetration electric fields pefs and disturbance dynamo electric fields ddefs play a decisive role in the ionospheric storm effects in low latitude and equatorial regions pefs occur on march 17 in both the american sector and the asian australian sector the effects of ddefs are also remarkable in the two longitudinal sectors both the ddefs and pefs show the notable local time dependence which causes the sector differences in the characteristics of the disturbed electric fields this differences would further lead to the sector differences in the low latitude ionospheric response during this storm the negative storm effects caused by the long duration ddefs are intense over the asian australian sector while the repeated elevations of hmf2 and the eia intensifications caused by the multiple strong pefs are more distinctive over the american sector especially the storm time f3 layer features are caught on march 17 in the american equatorial region proving the effects of the multiple strong eastward pefs

observations of ion neutral coupling associated with strong electrodynamic disturbances during the 2015 st patrick s day storm we use incoherent scatter radar observations at millstone hill mho and arecibo ao and topside ionosphere in situ dmsp observations during the great geomagnetic storm on 17 18 march 2015 to conduct a focused study on ion neutral coupling and storm time ionosphere and thermosphere dynamics some of these observations were made around the time of large ionospheric drifts within a sub auroral polarization stream saps during the storm main phase we identify multiple disturbance characteristics in the north american late afternoon and dusk sector 1 strong sub auroral westward drifts occurred between 20 24 ut near mho accompanied by a storm enhanced density plume passage over mho in the afternoon with a poleward upward ion drift the strongly westward flow reached 2000 m s speed near the poleward plume edge 2 prompt penetration electric field signatures appearing as poleward upward ion drifts on the dayside over both mho and ao were consistent with dmsp vertical drift data and contributed to plume development 3 meridional wind equatorward surges occurred during daytime hours at mho followed by 2 3 hr period oscillations at both mho and ao the zonal electric field at ao was strongly correlated with the wind oscillation 4 large ion temperature enhancements as well as 50 m s upward ion drifts throughout the e and f regions were observed during the saps period these were presumably caused by strong frictional heating due to large plasma drifts the heating effects appeared to drive significant atmospheric upwelling and corresponding ion upflow was also observed briefly this study highlights some of the important effects of fast plasma transport as well as other disturbance dynamics on ion neutral coupling during a single intensification period within a great geomagnetic storm

the influence of si b substitution and of the nature of network modifying cations on the properties and structure of borosilicate glasses and melts abstract the influence of the si b substitution and of the nature of network modifying cations on viscosities and heat capacities of ternary borosilicate melts has been investigated for two series of melts containing either 20 mol na 2 o or 33 mol bao the measurements have been made near the glass transition and above the liquidus for viscosities and from 300 to 1073 k for heat capacities they have been used to determine the configurational entropies of the melts from adam and gibbs theory of relaxation processes to complete these observations the room temperature raman spectra of the glasses have also been recorded the observed increase in the configurational heat capacity of melts with b 2 o 3 content indicates the existence of strong temperature induced structural changes induced by the presence of boron correlatively the viscosity variations with composition can be related to the existence of distinct coordination environments for boron as for the effects of barium and sodium they are similar in silicate and borosilicate melts and depend mainly on the field strength of the cation

distribution and stratigraphy of basaltic units in maria tranquillitatis and fecunditatis a clementine perspective maria tranquillitatis and fecunditatis have been mapped based on clementine image mosaics and derived iron and titanium maps impact craters served as stratigraphic probes enabling better delineation of compositionally different basaltic units determining the distribution of subsurface basalts and providing estimates of total basalt thickness and the thickness of the surface units collected data indicate that volcanism in these maria started with the eruption of low ti basalts and evolved toward medium and high ti basalts some of the high ti basalts in mare tranquillitatis began erupting early and were contemporaneous with the low and medium ti basalts these units form the oldest units exposed on the mare surface mare tranquillitatis is mostly covered with high ti basalts in mare fecunditatis the volume of erupting basalts clearly decreased as the ti content increased and the high ti basalts occur as a few patches on the mare surface the basalt in both maria is on the order of several hundred meters thick and locally may be as thick as 1600 m the new basalt thickness estimates generally fall within the range set by earlier studies although locally differ the medium to high ti basalts exposed at the surfaces of both maria are meters to tens of meters thick

lunar mare volcanism stratigraphy eruption conditions and the evolution of secondary crusts abstract lunar mare basalt deposits cover 17 of the lunar surface occur preferentially in topographic lows on the nearside and have a total volume estimated at 1 107 km3 analysis of returned samples and photogeologic and remote sensing studies shows that mare volcanism began prior to the end of heavy bombardment the period of cryptomare formation in pre nectarian times and continued until the copernican period a total duration approaching 3 5 4 ga stratigraphic analyses show that the flux was not constant but peaked in early lunar history during the imbrian period which spans the period 3 85 3 2 ga average volcanic output rate during this peak period was about 10 2 km 3 a very low relative to the present global terrestrial volcanic output rate and comparable to the present local output rates for individual volcanoes such as vesuvius and kilauea hawaii volcanic landforms indicate that many eruptions were of high volume and long duration some eruptions associated with sinuous rules may have lasted of the order of a year and emplaced 103 km3 of lava representing the equivalent in one year of about 70 000 years at the average flux shallow magma chambers were uncommon the nearsidefarside mare deposit asymmetry can be readily explained by differences in crustal thickness magma ascending from the mantle or from a buoyancy trap at the base of the crust should preferentially extrude to the surface on the nearside but should generally stall and cool in dikes in the farside crust extruding only in the deepest basins the occurrence of farside maria within craters whose diameter is generally near to or less than the thickness of the crust may be accounted for by the difference between local and regional compensation dikes that establish pathways to the surface on the nearside should have very high volumes comparable to the volumes associated with many observed flows and sinuous rilles an abundance of dikes should exist in the lower crust of the moon many more than those feeding surface eruptions the upper limit is 37 50 of the crust by volume the presence and abundance of such dike swarms have important implications for the interpretation of the average composition of the lunar crust and the composition of basin and crater ejecta the interplay between thermal contraction and differentiation leads to net cooling and ultimate contraction of the outer portions of the moon resulting in a regional horizontal compressive stress acting on the lunar crust in addition overall cooling and deepening of sources require the production of ever larger volumes of magma in order to reach the surface with time stresses became high enough so that few dikes could open to the surface causing eruptive activity to be severely diminished in the eratosthenian and perhaps to cease in the copernican period lower stress levels are required to terminate eruptive activity on the lunar farside consistent with the imbrian age of the farside maria and the nearside location of the youngest maria lunar mare deposits provide an example of the transition from primary crusts to secondary crusts and illustrate the significance of several factors in the evolution of secondary crusts such as crustal density variations in crustal thickness presence of impact basins state and magnitude of stress in the lithosphere and general thermal evolution these factors are also responsible for the extremely low volcanic flux even during periods of peak extrusion

variation of the equatorial height anomaly during the main phase of 2015 st patrick s day geomagnetic storm using annim and tiegcm

measurement and analysis of lunar basin depths from clementine altimetry altimetric profiles from the clementine lidar are used to calculate the depths of 29 large craters and basins on the moon plotting the depths of the best preserved structures together with values for simple and complex craters measured in pre clementine studies reveals an inflection in the depth diameter d d curve in addition to the one revealed by pre clementine data this inflection occurs in the diameter range that corresponds to the morphologic transition from complex crater to basin the best empirical power law fit for basin depths is log10 d 0 41 log10 d 0 57 this relationship is characterized by a lower slope than that for complex craters demonstrating that this morphologic transition corresponds to a further decrease in the depth of an impact structure relative to its diameter with increasing size qualitative consideration of possible causes for the second inflection leads to the conclusion that it is most likely a consequence of a short term modification mechanism that influences fundamental crater morphology such as the increasing influence of gravity with diameter thicknesses of maria in the major basins are calculated by assuming that their unfilled depths would follow thed drelation results are compared with previous estimates and yield thicknesses that are generally greater than those determined by studies of flooded craters and less than those obtained from analysis of gravity

basalt thickness in mare humorum the crater excavation method basalt thicknesses in mare basins have been determined using assumptions about the premare topography of partly buried craters and by comparison to the orientale basin differences in those assumptions have led to a factor of 4 difference in mare thickness estimates further knowledge of thickness is restricted to areas in which buried craters are present using mixing models applied to multispectral images acquired by the clementine spacecraft we have shown that craters in the mare sometimes excavate highland material from below the mare cover using such craters and assumptions about their depth of excavation we obtain independent estimates of basalt thickness our results are in agreement with the lowest of previous thickness estimates we derive a volume of 40 000 km 3 for basalts in mare humorum considerably less than the 110 000 km 3 from previous estimates we also confirm a diameter of 425 km for thc humorum multiring basin based on the clementine gridded global topography assuming an original morphology like orientale

structure and properties of lime alumino borate glasses the aim of our study is to investigate the structural effects of the substitution of aluminum by boron in lime alumino borate glasses in this case a competition between two network formers can be observed it was proven that aluminum can be in four five and six fold coordination in calcium aluminate and aluminosilicate glasses whereas boron can be in three and four fold coordination in borate and borosilicate glasses to understand what happens when boron replaces aluminum different glasses were made starting with ca aluminate glass c12al14o33 i e c12a7 in cement nomenclature and then progressively substituting aluminum by boron until b fully replaces al raman 11b nmr and 27al nmr spectroscopies were used to investigate the structure of these glasses at medium and short range order respectively density dsc measurements were also done in order to characterize properties at a macroscopic scale nmr and raman spectra show that aluminum in ca aluminate glass c12a7 is in four fold coordination more precisely in t3 and t4 species tn indicates aluminum in tetrahedral sites with n bridging oxygens whereas when boron replaces aluminum bo3 are the main species formed in good agreement with the two spectroscopic methods these triangular units break the tetrahedral network already formed by alo4 leading to an important drop of tg as the concentration of boron increases nbos are formed to create bo4 tetrahedral units with the presence of calcium acting as a charge compensator these tetrahedral structures start to increase the polymerization of the network glass transition temperature tg continues to decrease but with a slower decline in this study we will present all these results and discuss the influence of the structure of the network on the macroscopic parameters

responses in the polar and equatorial ionosphere to the march 2015 st patrick day storm the st patrick day storm of 2015 17 march 2015 occurred at a unique time when there were multiple spacecraft observing the earth s ionosphere between 350 and 885 km observations of the plasma flows and densities from the five operational polar orbiting dmsp spacecraft combined with those from the equatorial orbiting c nofs spacecraft provided a comprehensive global record of the both the polar and equatorial ionosphere regions responses to the storm this paper presents an overview of the data from this suite of spacecraft focusing on the following aspects 1 the polar cap ionosphere s reaction to the storm 2 the change in the penetration electric field in the midlatitude region as a function of time and the solar local time during the storm 3 the equatorial ionosphere s response of the meridional vertical flows to the penetration electric field and the disturbance dynamo during the storm and 4 the creation of a predawn ionospheric bubble system near the equator during the storm s main phase that was observed at low altitudes by c nofs and later at high altitudes by several dmsp examining these phenomenon enable us to trace the dynamic flow of energy from the solar wind input in the polar ionosphere all the way to the equatorial ionosphere

electrodynamic disturbances in the brazilian equatorial and low latitude ionosphere on st patrick s day storm of 17 march 2015 the st patrick s day storm of 17th march 2015 has a long lasting main phase with the dst reaching a minimum of 223 nt during the main phase two strong prompt penetration electric field ppef phases took place first with the southward turning of imf bz around 1200 ut and the second with the onset of a substorm around 1725 ut leading to strong equatorial zonal electric field enhancements the consequent spatio temporal disturbances in the ionospheric total electron content tec and the resultant modifications in the equatorial ionization anomaly eia over the brazilian longitudinal sector are investigated in detail the simultaneous measurements from a large network of gps receivers ionosonde and magnetometers over the brazilian longitudinal sector are used for this study in the presence of enhanced zonal electric field the equatorial f2 layer peak hmf2 experienced a rapid uplift without any significant change in the base height h f while the f2 layer is redistributed into f2 and f3 layers the enhanced zonal electric filed due to ppef led to the strong super fountain effect under which the anomaly crest departed poleward to 40o s latitude in the presence of westward and equatorward wind surge over brazil with the co existing disturbance dynamo fields strong hemispheric asymmetry is seen in the storm time response of eia during both the ppef phases

a study of the weddell sea anomaly observed by formosat 3 cosmic 1 more than two years of cosmic electron density profiles at low solar activities are collected to study the evolution of the weddell sea anomaly wsa which appears as an evening enhancement in electron density during local summer observations show that the change in nmf2 the f2 peak electron density is associated with the change in hmf2 the f2 peak height while the latter is correlated closely with the components of the geomagnetic field we find that 1 in the afternoon hmf2 is more liable to rise drastically in regions with a larger jsin 2i j value which would occur early at certain declinations eastward in the southern hemisphere and westward in the northern hemisphere 2 subsequently a larger increment of hmf2 is coincidentally followed by a stronger enhancement of nmf2 and the enhancement ends just around the local sunset and 3 in midlatitudes the evolution pattern of hmf2 in the evening of equinoxes and winter is similar to that in summer albeit without a lasting nmf2 enhancement as that in summer these features suggest that the nmf2 enhancement and the hmf2 increase could arise from the thermospheric wind effect and solar photoionization plays a crucial role in the enhancement as well the general midlatitude f2 layer enhancement in local summer evening is consistent with the wsa on the above features indicating that the wsa is a manifestation with a particular geometry of the magnetic field of the evening enhancement induced by the winds

the lunar crust global structure and signature of major basins new lunar gravity and topography data from the clementine mission provide a global bouguer anomaly map corrected for the gravitational attraction of mare fill in mascon basins most of the gravity signal remaining after corrections for the attraction of topography and mare fill can be attributed to variations in depth to the lunar moho and therefore crustal thickness the large range of global crustal thickness 20 120 km is indicative of major spatial variations in melting of the lunar exterior and or significant impact related redistribution the 61 km average crustal thickness constrained by a depth to moho measured during the apollo 12 and 14 missions is preferentially distributed toward the farside accounting for much of the offset in center of figure from the center of mass while the average farside thickness is 12 km greater than the nearside the distribution is nonuniform with dramatic thinning beneath the farside south pole aitken basin with the global crustal thickness map as a constraint regional inversions of gravity and topography resolve the crustal structure of major mascon basins to half wavelengths of 150 km in order to yield crustal thickness maps with the maximum horizontal resolution permitted by the data the downward continuation of the bouguer gravity is stabilized by a three dimensional minimum slope and curvature algorithm both mare and non mare basins are characterized by a central upwarped moho that is surrounded by rings of thickened crust lying mainly within the basin rims the inferred relief at this density interface suggests a deep structural component to the surficial features of multiring lunar impact basins for large 300 km diameter basins moho relief appears uncorrelated with diameter but is negatively correlated with basin age in several cases it appears that the multiring structures were out of isostatic equilibrium prior to mare emplacement suggesting that the lithosphere was strong enough to maintain their state of stress to the present

observations and simulations of the ionospheric and thermospheric response to the december 2006 geomagnetic storm initial phase 1 we have investigated the thermospheric and ionospheric response to the 14 15 december 2006 geomagnetic storm using a coupled magnetosphere ionosphere thermosphere cmit 2 0 model simulation in this paper we focus on observations and simulations during the initial phase of the storm about 8 h when the shock was driving changes in geospace the global ionospheric maps of total electron content tec ionosonde data at four stations and millstone hill incoherent scatter radar isr observations are compared with the corresponding simulation results from the cmit model the observations showed significant positive storm effects occurred in the atlantic sector after the onset of this storm the cmit model is able to capture the temporal and spatial variations of the ionospheric storm effects seen in the gps tec observations although the model slightly underestimates the daytime positive ionospheric storm in the south american sector the simulations are also in agreement with the ionosonde and isr ionospheric measurements term analysis of the ion continuity equation demonstrates that changes in the electric fields play a dominant role in generating the observed ionospheric positive storm effect in the american sector during the initial phase although neutral winds and composition changes also contribute the difference in the strength of the enhancements over north and south america can be explained by the slope of the topside electron density profiles in the two hemispheres in the southern hemisphere electron densities decrease slowly with altitude whereas the decrease is much more rapid in the northern winter hemisphere the electric fields therefore cannot cause large increases in electron density by uplifting the plasma so positive storm effects are small in the southern hemisphere compared with the northern hemisphere even though the increase in hmf2 is greater in the southern hemisphere nighttime changes in electron density in other longitude sectors are small because the topside electron densities also decrease slowly with altitude at night

penetration of magnetospheric electric fields to the equator during a geomagnetic storm 1 penetration of the magnetospheric electric field to the equatorial ionosphere was examined for the geomagnetic storm on 6 november 2001 by analyzing the difference in magnitude of the geomagnetic storm recorded at the dayside geomagnetic equator yap 0 3 gml and low latitude okinawa 14 47 gml the penetrated electric field caused the dp2 currents at the equator i e eastward currents during the main phase of the storm while the overshielding currents i e westward currents dominated during the recovery phase it is shown that the ring current started to develop simultaneously with the onset of the equatorial dp2 within the temporal resolution of a few minutes these results imply prompt transmission of the dawn to dusk convection electric field to the inner magnetosphere as well as to the equatorial ionosphere it is found that the equatorial dp2 started to decrease one hour after the onset of the ring current development indicating shielding effects becoming effective at the equator during the latter half of the storm main phase the dp2 was then overwhelmed by the overshielding which resulted in the counter electrojet cej in the beginning of the storm recovery phase the image magnetometer chain data indicate that the westward auroral electrojet aej in the dawn sector was driven over midlatitude centered at 57 corrected geomagnetic latitude cgml during the main phase while the aej shifted rapidly poleward to the auroral latitude centered at 67 cgml in the beginning of the recovery phase the overshielding must be caused by the abrupt poleward shift of the rl facs as inferred from the poleward shift of the aej in addition to the decrease in their magnitude due to the decrease in magnitude of the southward imf the geomagnetic storm at the dayside geomagnetic equator was enhanced in amplitude with the ratio of 2 7 as compared with the geomagnetic storm at low latitude this amplification is a result of both effects of the dp2 currents and the cej associated with the main and recovery phases respectively it is suggested that the electric field associated with the dp2 currents contributed to the development of the ring current during the main phase while the overshielding electric field may contribute to cease developing the ring current during the recovery phase

lunar iron and titanium abundance algorithms based on final processing of clementine ultraviolet visible images the clementine mission to the moon returned global imaging data collected by the ultraviolet visible uvvis camera this data set is now in a final state of calibration and a five band multispectral digital image model dim of the lunar surface will soon be available to the science community we have used observations of the lunar sample return sites and stations extracted from the final dim in conjunction with compositional information for returned lunar soils to revise our previously published algorithms for the spectral determination of the feo and tio2 content of the lunar surface the algorithms successfully normalize the effects of space weathering so that composition may be determined without regard to a surface s state of maturity these algorithms permit anyone with access to the standard archived dim to construct high spatial resolution maps of feo and tio2 abundance such maps will be of great utility in a variety of lunar geologic studies

double crests of peak height in the equatorial ionospheric f2 layer observed by cosmic for the first time we report daytime double crests of peak height hmf2 in the f2 layer based on the constellation observing system for meteorology ionosphere and climate cosmic observations during 2007 2014 evident double crests of hmf2 occurred at around 10 geomagnetic latitude with a trough over the magnetic equator at low solar activity and at march equinox this phenomenon is referred to as an equatorial height anomaly eha of the ionospheric f2 layer the double crests became less obvious at september equinox and disappeared at solstices at solstices only one crest was observed in the summer hemisphere which is probably associated with transequatorial neutral winds in addition the double eha crests generally take place during 10 00 14 00 local times our results indicate that the eha favors the conditions of strong vertical plasma drifts and weak transequatorial neutral winds during low solar activity the eha feature is reproduced by the thermosphere ionosphere electrodynamics global circulation model at march equinox and low solar activity

raman spectra and structure of baosio2 srosio2 and caosio2 melts to 1600 c abstract raman spectra were collected for barium silicate strontium silicate and calcium silicate melts at temperatures ranging from the glass transition region to temperatures as high as 1600 c for melts less polymerized than disilicate the spectra were used to determine the relative abundances of the q3 q2 and q1 tetrahedra and the si2o52 sio32 and si2o76 structural units in the melts a concentration constant was computed for the reaction 4 sio 2 3 sio 2 5 si 2 o 6 7 and was found to vary with composition from approximately log10kc 0 5 for barium silicate melts with nbo si 1 143 to log10kc 1 75 for calcium metasilicate melts with nbo si 2 little difference was found to exist in the structural behavior of the melts on the three alkaline earth silicate binary joins activity coefficients were computed for the sio2 3 structural unit as a function of bulk composition the logarithm of the activity coefficients and mole fraction of the structural unit are linearly correlated

three dimensional ionospheric electron density structure of the weddell sea anomaly 1 this paper provides the first three dimensional description of the ionospheric density structure of the weddell sea anomaly wsa the wsa is characterized by a nighttime ionospheric density greater than that in daytime in the weddell sea region around the antarctic peninsula during the southern hemisphere summer it was first observed by ground based ionosondes located in the antarctica back in the 1950s and was further investigated by two dimensional maps over the oceans using tec measurements collected by the topex poseidon recently although these tec maps have provided two dimensional views for tracking the time evolution and spatial coverage of the wsa the vertical distribution of this peculiar feature is still unavailable with the vertical ionospheric density profiles observed by the formosat 3 cosmic three dimensional density structure of the wsa is presented here for the first time meanwhile a similar wsa signature is observed in the northern and eastern hemisphere during june solstice by both the gps tec and the formosat 3 cosmic electron density observations from the observed altitudinal structure of the wsa during 1800 2400 lt and the similar feature occurred in the opposite hemisphere suggest that the southward offset of the magnetic equator with respect to the geographic equator plays a major role for the wsa formation

clementine images of the lunar sample return stations refinement of feo and tio2 mapping techniques clementine uvvis images of the lunar sample return sites have been processed and used to produce refined calibrations for the iron and titanium determination algorithms of lucey et al 1995 1996 the high spatial resolution of the clementine data permits individual sampling stations to be resolved at the apollo 15 16 and 17 landing sites we find an excellent linear correlation between the spectral fe and ti parameters and the average feo and tio 2 contents of soils sampled at each site or station this correlation demonstrates that these techniques can confidently be applied to other areas of the moon the luna 24 site does not fit the ti relation found for other sites suggesting that either its sample is nonrepresentative or the reported landing coordinates are incorrect

geospace system responses to the st patrick s day storms in 2013 and 2015 this special collection includes 31 research papers investigating geospace system responses to the geomagnetic storms during the st patrick s days of 17 march 2013 and 2015 it covers observation data assimilation and modeling aspects of the storm time phenomena and their associated physical processes the ionosphere and thermosphere as well as their coupling to the magnetosphere are clearly the main subject areas addressed this collection provides a comprehensive picture of the geospace response to these two major storms we provide some highlights of these studies in six specific areas 1 global and magnetosphere plasmasphere perspectives 2 high latitude responses 3 subauroral and mid latitude processes 4 effects of prompt penetration electric fields and disturbance dynamo electric fields 5 effects of neutral dynamics and perturbation and 6 storm effects on plasma bubbles and irregularities we also discuss areas of future challenges and the ways to move forward in advancing our understanding of the geospace storm time behavior and space weather effects

low latitude ionospheric height variation as observed by meridional ionosonde chain formation of ionospheric ceiling over the magnetic equator a multipoint ionosonde observation campaign was conducted along the magnetic meridional plane in southeast asia to study ionosphere thermosphere coupling one station was near the magnetic equator and two of the other stations were at off equatorial latitudes 10 magnetic latitude the daytime ionospheric peak height hmf2 was analyzed for each season during the solar minimum years 2006 2007 and 2009 the peak height increased for 3 h after sunrise at the magnetic equator and off equatorial latitudes as expected from the daytime upward e b drift the apparent upward drift at the magnetic equator ceased before noon while the drift at the off equatorial latitudes continued upward and the layer height exceeded the equatorial height around noon the noontime limited layer peak height at the magnetic equator which was termed the ionospheric ceiling did not depend on the season while the maximum peak height at the off equatorial latitudes largely varied with each season numerical modeling using the sami2 code was conducted and the features of the ionospheric ceiling were reproduced quite well the dynamical parameters provided by the sami2 modeling runs showed that the ionospheric ceiling is formed by the field aligned plasma diffusion which is a part of the fountain effect

iron abundances on the lunar surface as measured by the lunar prospector gamma ray and neutron spectrometers i global measurements of iron abundances on the lunar surface are presented using data from the lunar prospector lp gamma ray spectrometer grs and neutron spectrometer ns in this study we derive relative iron abundances from the low altitude high spatial resolution 45 km 2 lp data using the 7 6 mev neutron capture gamma ray doublet as part of the lp grs analysis we demonstrate the importance of accounting for variations in neutron number density across the lunar surface by measuring neutron fluxes using lp ns data in a first step of comparing the lp grs data with previously published iron abundances inferred from clementine spectral reflectance csr data we show that the existing csr feo data are nonlinear with respect to the lp relative iron abundances we use the lp data to linearize the relationship between the csr and the relative iron values then recalibrate the csr data to iron abundance using returned soil abundances we then correlate the csr data except for major anomalies with the lp relative iron measurements to convert the lp data to absolute iron abundances when we compare the lp grs and revised csr data sets we find a very good correspondence there are two locations mare tranquillitatis and south pole aitken spa basin that show major discrepancies suggesting that the csr data are locally overestimating iron abundances in both these regions the discrepancies identified by the lp grs csr comparison are possibly explained by mineralogical differences that are not accounted for in the csr to feo calibration in regards to our understanding of the moon the lp data have found the following i there exist large expanses of mare basalt in the western mare regions that have very high iron abundances 22 23 wt feo that are underrepresented but not absent from the returned sample collection and are highly unusual for mare soils which typically contain a significant amount of highlands contamination 2 the low iron abundances in the lunar highlands 5 feo wt are consistent with a previous analysis using thermal and epithermal neutrons and with the idea that the lunar crust formed by a relatively simple magma ocean process 3 the comparison of lp and csr derived iron abundances suggests that the material within spa basin is similar to a norite type rock without an enriched mantle feo signature 4 a comparison of lp and csr data at tycho crater shows a large discrepancy such that the csr data show moderate iron abundances of 8 9 wt feo while the lp data show very low iron abundances of 3 4 wt feo this discrepancy cannot yet be easily explained by any known process

equatorial ionization anomaly in the low latitude topside ionosphere local time evolution and longitudinal difference although the equatorial ionization anomaly eia has been widely studied it was seldom investigated from observations for the topside ionosphere in this paper the climatology characteristics of the latitudinal structure of topside ion density ni were investigated in detail using rocsat 1 and dmsp ni observations eia double peak structure may exist at 600 km depending on longitude local time season and solar activity while it is not a prevalent characteristic at 840 km even at solar maximum sunset local time evolution of the eia at 600 km was presented the double peak structure begins to appear at noontime being later than the appearance of the eia in f2 peak region the pronounced eia induced by the strong prereversal enhancement at solar maximum begins to appear at 19 00 lt and can last to pre midnight eia crest to trough ratio ctr is largest lowest at march equinox june solstice and reaches a maximum at 20 00 lt in all seasons eia structure shows evident longitudinal difference pronounced eia exists around about 100 e at 13 00 lt at the two equinoxes and june solstice while it exists at more extensive longitudes about 90 e to 240 e at december solstice the trans equator plasma transport induced by neutral winds can weaken the double peak structure in the topside ionosphere the longitudinal difference in the eia structure at 600 km is related to the longitudinal variations of equatorial upward plasma drift and geomagnetic declination