migrating and nonmigrating semidiurnal tides in the upper atmosphere excited by tropospheric latent heat release migrating and nonmigrating semidiurnal tides

mass and heat flux of volcanic gas discharging from the summit crater of iwodake volcano satsuma iwojima japan during 1996 1999 abstract volcanic gas of iwodake has been discharged continuously from high temperature 900 c maximum fumaroles and a degassing vent which formed on the central floor of the summit crater after 1994 although most of the high temperature fumaroles located on the crater wall before 1991 many fumaroles appeared on the crater floor associated with the vent opening suggesting a shift of thermal activity from the peripheral to the central crater a large amount of volcanic gas has been discharged from the fumaroles and vent since heat has been transferred from ascending gas to the surrounding soil a region showing a surface temperature anomaly has developed around the fumaroles and vent to quantify iwodake thermal activity heat and volcanic gas mass fluxes were estimated during 1996 1999 using infrared thermal images and plume velocity and temperature data which were observed by a pitot tube and thermocouple the estimated gas mass flux was compared with the cospec data to investigate the accuracy of our estimation the gas mass flux had been decreased from 230 kg s in october 1996 to 30 kg s in november 1999 although the vent diameter had increased from 20 to 70 m during the same period this mass flux variation had indicated the decline of degassing rate the degassing depth was estimated from the volcanic gas mass flux and temperature the depth showed a tendency of magma head migration to shallower depth during 1996 1999 which was consistent with the drastic change of the surface manifestation

eruption mechanism as inferred from geomagnetic changes with special attention to the 1989 1990 activity of aso volcano abstract geomagnetic changes associated with the volcanic activity of aso volcano were detected with a dense network of continuously recording proton precession magnetometers during the period from june 1989 to june 1990 magnetic date clearly indicate that changes in the magnetization within the volcano are most probably caused by temperature changes this activity can be divided into five stages which are characterized by magnetization and demagnetization of the volcano these magnetic changes with durations of a few months are definitely correlated with some typical volcanic events at the crater as well as the volcanic tremor activity the demagnetization stage appears when the vent is covered by a water pool or the volcanic activity is enhanced the magnetization stage follows the opening of a vent and several large explosions which make the vent permeable the source of magnetic changes lies at a depth of about 200 m below the crater rim in the southwestern part of the active crater magnetic moments responsible for observed magnetic changes at stages 1 2 and 4 are 3 4 5 2 and 2 2 wbm respectively the corresponding source volume is estimated as a single sphere of radius 40 50 m or a spherical shell of 100 m or so an effective mechanism of rapid heating cooling exists which is ascribed to the interaction of groundwater and superheated vapor i e a shallow hydrothermal system this hydrothermal system driven by the surface cap of the vent controls every feature of the eruptions at the final outlet of aso volcano

simulation of equatorial electrojet magnetic effects with the thermosphere ionosphere electrodynamics general circulation model 1 in this work the magnetic variations simulated by the ncar thermosphere ionosphere electrodynamics general circulation model tie gcm in the vicinity of the magnetic equator are examined to evaluate the ability of this model to reproduce the major features of the equatorial electrojet eej as observed on the ground as well as on board low altitude orbiting satellites the tie gcm simulates electric currents of various origins and reproduces their associated magnetic perturbations we analyze the diurnal and latitudinal variations of the eej magnetic effects calculated on the ground in west africa under approximately the same solar activity condition as in 1993 for the march equinox and june and december solstices the latitudinal and local time structures of these simulated results correspond well to those that are observed we also compare longitudinal variations of the midday eej magnetic perturbations observed by the champ satellite with the model predictions although the simulations and observations both show multiple maxima and minima in longitude the locations of these extrema often disagree in the model most of the longitudinal variation of the magnetic variations is associated with nondipolar structure of the geomagnetic field we find that the modeled contributions of the thermospheric migrating diurnal and semidiurnal tides to the magnetic perturbations have large longitudinal variations and we suggest that an increase in the amplitude of these tides in the tie gcm may cause them to play a major role in explaining the morphology of the eej longitudinal variation

a reconstructed dynamic indian monsoon index extended back to 1880 the authors present a reconstruction of summer june july august mean dynamic indian monsoon index dimi back to 1880 based on a large number of historical surface observation data as well as information from the upper air data the reconstruction shows a satisfying skill in terms of both the value of reduction of error and an evaluation against other independent monsoon indices the skill of reconstruction increases over time with more predictor data in particular upper level data becoming available a comparison with the observed all indian summer monsoon rainfall index airi shows a high consistence in both inter decadal and inter annual variability the reconstruction shows stronger than normal monsoon during the 1880s 1915 1925 around 1920 and 1930 1945 around 1940 as the airi the el nino southern oscillation enso monsoon relationship is reasonably captured in the reconstruction powers concentrating within quasi biennial band stand out in the reconstruction as well as in the airi a comparison of the reconstruction against an atmospheric general circulation model simulation with specified sst and external forcing agents spanning 1901 1999 indicates a slightly higher reproducibility of monsoon circulation than monsoon rainfall in terms of interannual variability the relationship between the asian continent warming and the enso monsoon connection is also discussed by using the new dynamic index

on the relationship between weakening of the northern polar vortex and the lunar tidal amplification in the equatorial electrojet enhanced lunar tidal effects in the equatorial electrojet eej during northern winters in the form of big l days have been known for a long time recent studies suggest that the changes in the tidal propagation conditions due to stratospheric sudden warmings ssw could be responsible for this phenomenon in this work we have used the h component of the magnetic field recorded at huancayo from 1997 2013 to study the relation between the timing and magnitude of the semi monthly lunar tide in the eej and the stratospheric polar vortex weakening pvw we prefer a definition of pvw by taking into account the atmospheric conditions from december to february for each winter our results indicate that the semi monthly lunar tide in the eej gets enhanced during northern winters when a significant pvw occurs and its peak timing and magnitude is correlated with the timing and intensity of pvw the timing of lunar tidal peaks and pvw correlate better than their respective magnitudes our results suggest that the initiation of the lunar tidal enhancement in most of the cases is closely related to a pvw event furthermore we discuss events where the semi monthly lunar tidal enhancements are not well timed with respect to pvw we also suggest that the amount of tropospheric forcing into the stratosphere plays a major role in the enhancement of the lunar tides in the eej

the equatorial counter electrojet part of a worldwide current system 1 the method of natural orthogonal components was applied to the ground geomagnetic data in the central asian sector 72 83 e during the summer months of 1995 in an attempt to identify additional current systems that are superposed on the normal sq current vortex and related to the equatorial counter electrojet cej the principal components when examined in equivalent current representation provide useful insights into the behavior of ionospheric current systems on different days statistical analyses performed in the present work suggest a possible relationship between the cej field and the noontime d variation observed at low latitudes the results are in conformity with an earlier global simulation model

variabilities of the equatorial electrojet in brazil and peru 1 this report presents seasonal and longitudinal variabilities of the equatorial electrojet in the east brazil sao luis 2 3 s 315 8 e 0 5 s dip latitude and west jicamarca peru 11 95 s 283 13 e 0 6 n dip latitude coasts of the continent of south america ground based magnetic field perturbation measurements h for solar maximum 2001 2002 and solar minimum 2006 2007 conditions from the two equatorial stations sao luis and jicamarca have been used for the study the h signal which is a measure of the strength of the equatorial electrojet is spectrally analyzed using wavelet analysis the results of our analysis show that 1 the equatorial electrojet has maxima around equinoxes in jicamarca peru but it has a prominent maximum during southern hemisphere summer centered about december january in sao luis brazil the observed seasonal behavior of the equatorial electrojet in sao luis is highly likely due to the large magnetic declination angle about 20 west there 2 the equatorial electrojet is stronger in the west coast jicamarca compared to the east coast sao luis irrespective of solar activity condition 3 the magnitude of the equatorial electrojet is more variable with season and solar cycle over sao luis than over jicamarca

rain vapor interaction and vapor source identification using stable isotopes from semiarid western india 1 results of a 4 year 2005 2008 study of stable isotopic composition of daily rain and ground level vapor glv at a semiarid station in western india are reported the glv samples were collected by complete cryogenic trapping the sampling was mostly limited to the rainy season june july august and september and about a month before and after the maximum number of samples was collected during the year 2007 the glv has a steady baseline 18o and d composition without distinguishable seasonal differences the d excess of glv indicates that its isotopic composition has a significant contribution from kinetic evaporation of nonlocal water sources during a rain event glv rapidly interacts with raindrops and tends to move toward isotopic equilibrium on cessation of rain the 18o and d of glv quickly return to the typical baseline values therefore use of isotopic composition of monthly rainfall for estimating average monthly isotopic composition of glv can lead to erroneous results within a rainy season certain large rain events have depleted 18o and d values compared to other equally large rain events with significantly enriched 18o and d these isotopic differences are apparently not related to amount of rainfall variable magnitude of evaporation from falling raindrops and or cloud liquid water fraction cannot explain the observed differences instead it is shown that varying source regions arabian sea or bay of bengal and cloud top temperature may be responsible for observed differences

continuing deflation by fumaroles at kuju volcano japan 1 a phreatic eruption occurred at kuju volcano in october 1995 we deployed an edm network around the active craters of the volcano just after the eruption slope distances of the survey lines in the northern network have tended to contract whereas those in the southern one extended the maximum contraction observed in the northern network was 70 cm over 6 years a spherical volume decrease just beneath a fumarolic area called iwoyama 700 m north of the new craters is a plausible model for these changes in slope distances a noteworthy feature is that over 6 years after the phreatic eruption ended the deflation rate is still approximately linear we also estimated the thermal energy discharge by fumaroles in the new craters which proved to be well correlated with the observed deflation rate it is strongly suggested that deflation of a geothermal reservoir not any magmatic effect causes the ground deformation around iwoyama

the equatorial electrojet during geomagnetic storms and substorms the climatology of the equatorial electrojet during periods of enhanced geomagnetic activity is examined using long term records of ground based magnetometers in the indian and peruvian regions equatorial electrojet perturbations due to geomagnetic storms and substorms are evaluated using the disturbance storm time dst index and auroral electrojet ae index respectively the response of the equatorial electrojet to rapid changes in the ae index indicates effects of both prompt penetration electric field and disturbance dynamo electric field consistent with previous studies based on f region equatorial vertical plasma drift measurements at jicamarca the average response of the equatorial electrojet to geomagnetic storms dst 50 nt reveals persistent disturbances during the recovery phase which can last for approximately 24 h after the dst index reaches its minimum value this after storm effect is found to depend on the magnitude of the storm solar euv activity season and longitude

can oxygen stable isotopes be used to track precipitation moisture source in vascular plant dominated peatlands a b s t r a c t variations in the isotopic composition of precipitation are determined by fractionation processes which occur during temperature and humidity dependent phase changes associated with evaporation and condensation oxygen stable isotope ratios have therefore been frequently used as a source of palaeoclimate data from a variety of proxy archives which integrate this signal over time applications from ombrotrophic peatlands where the source water used in cellulose synthesis is derived solely from precipitation have been mostly limited to northern hemisphere sphagnum dominated bogs with few in the southern hemisphere or in peatlands dominated by vascular plants new zealand nz provides an ideal location to undertake empirical research into oxygen isotope fractionation in vascular peatlands because single taxon analysis can be easily carried out in particular using the preserved root matrix of the restionaceous wire rush empodisma spp that forms deep holocene peat deposits throughout the country furthermore large gradients are observed in the mean isotopic composition of precipitation across nz caused primarily by the relative influence of different climate modes here we test whether 18o of empodisma cellulose from ombrotrophic restiad peatlands in nz can provide a methodology

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

equatorial electrojet responses to intense solar flares under geomagnetic disturbance time electric fields large enhancement in the equatorial electrojet eej current can occur due to sudden increase in the e layer density arising from solar flare associated ionizing radiations as also from background electric fields modified by magnetospheric disturbances when present before or during a solar flare we investigate the eej responses at widely separated longitudes during two x class flares that occurred at different activity phases surrounding the magnetic super storm sequences of 28 29 october 2003 during the 28 october flare we observed intense reverse electrojet under strong westward electric field in the sunrise sector over jicamarca sources of westward disturbance electric fields driving large eej current are identified for the first time model calculations on the e layer density with and without flare and comparison of the results between jicamarca and sao luis suggested enhanced westward electric field due to the flare occurring close to sunrise over jicamarca during the flare on 29 october which occurred during a rapid ae recovery a strong overshielding electric field of westward polarity over jicamarca delayed an expected eej eastward growth due to flare induced ionization enhancement in the afternoon this eej response yielded a measure of the overshielding decay time determined by the storm time region 2 field aligned current this paper will present a detailed analysis of the eej responses during the two flares including a quantitative evaluation of the flare induced electron density enhancements and identification of electric field sources that played dominant roles in the large westward eej at the sunrise sector over jicamarca

volcanic plume thermal radiation 1972 eruption of piton de la fournaise reunion island abstract using an infrared radiometer the authors measured the infrared radiation emitted by the plume during the 1972 piton de la fournaise reunion island eruption in the 9 1 to 11 9 m range eight histograms summarize twenty hours of continuous measurements and show a flux between 0 557 and 1 279 w cm 2 with an average of 0 88 w cm 2 the greatest number of events correspond to the flux emitted by lava fountains while the high and rare flux values 4 6 w cm 2 correspond to detonations of chemical explosions probably of h 2 and o 2 after calibration in the laboratory on a reference black body and in the field by correlation with field observations such a technique can be used to follow changes of volcanic activity in remote and dangerous spots information on the number of explosions their magnitude and the presence and relative significance of hot magma can be transmitted continuously to a safe place

the storm time evolution of the ionospheric disturbance plasma drifts in this paper we use the c nofs and rocsat 1 satellites observations to analyze the storm time evolution of the disturbance plasma drifts in a 24 hour local time scale during three magnetic storms driven by long lasting southward imf bz the disturbance plasma drifts during the three storms present some common features in the periods dominated by the disturbance dynamo the newly formed disturbance plasma drifts are upward and westward at night and downward and eastward during daytime further the disturbance plasma drifts are gradually evolved to present significant local time shifts the westward disturbance plasma drifts gradually migrate from nightside to dayside meanwhile the dayside downward disturbance plasma drifts become enhanced and shift to later local time the local time shifts in disturbance plasma drifts are suggested to be mainly attributed to the evolution of the disturbance winds the strong disturbance winds arisen around midnight can constantly corotate to later local time at dayside the westward and equatorward disturbance winds can drive the f region dynamo to produce the poleward and westward polarization electric fields or the westward and downward disturbance drifts the present results indicate that the disturbance winds corotated to later local time can affect the local time features of the disturbance dynamo electric field

evaluation methods of heat discharge and their applications to the major active volcanoes in japan abstract the rates at which thermal energy is released by non eruptive mechanisms associated with active volcanoes in japan have been estimated from surface temperature distributions or from shapes of the fumarolic plume rise values of 5 3 x 107 w and 1 2 x 108 w have been calculated for non eruptive release rates in 100 km segments of the northeast and the southwest japan arc respectively it appears that non eruptive heat discharge is of the same order as that caused by eruptions

global features of quiet time counterelectrojet observed by orsted 1 the present work investigates the reverse equatorial electrojet signature seen in the orsted satellite data during magnetically quiet conditions we found that whenever the satellite sees the reverse electrojet signature over the indian region it is always accompanied by the counterelectrojet cej at indian observatories and therefore the reverse electrojet signature at the satellite height can be considered a proxy for the cej observed on the ground then using satellite observations global features of the cej phenomenon are obtained the broad features of the phenomenon such as a seasonal variation of the cej occurrence frequency and also its anticorrelation with the normal electrojet strength are found to be in agreement with earlier ground based studies satellite based investigations have a distinct advantage over ground data for studying the global extent as well as the longitudinal variation of the cej occurrence it is observed that in general the longitudinal extent of the phenomenon is very narrow often restricted to less than 25 however the present analysis suggests that strong westward currents generated at a given universal time can result in cej at wider longitudinal locations the percentage of cej occurrence is found to be highest in the brazilian sector between 300 e and 330 e longitude it is observed that the cej is prone to occur where the magnetic declination is large highlighting the role of the geometry of the ambient geomagnetic field the present study emphasizes that the cej occurs more favorably when and where the strength of the normal equatorial electrojet is weak

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

day to day variability of equatorial electrojet and its role on the day to day characteristics of the equatorial ionization anomaly over the indian and brazilian sectors the equatorial electrojet eej is a narrow band of current flowing eastward at the ionospheric e region altitudes along the dayside dip equator mutually perpendicular electric and magnetic fields over the equator results in the formation of equatorial ionization anomaly eia which in turn generates large electron density variabilities simultaneous study on the characteristics of eej and eia is necessary to understand the role of eej on the eia variabilities this is helpful for the improved estimation of total electron content tec and range delays required for satellite based communication and navigation applications present study reports simultaneous variations of eej and gps tec over indian and brazilian sectors to understand the role of eej on the day to day characteristics of the eia magnetometer measurements during the low solar activity year 2004 are used to derive the eej values over the two different sectors the characteristics of eia are studied using two different chains of gps receivers along the common meridian of 77 e india and 45 w brazil the diurnal seasonal and day to day variations of eej and tec are described simultaneously variations of eia during different seasons are presented along with the variations of the eej in the two hemispheres the role of eej variations on the characteristic features of the eia such as the strength and temporal extent of the eia crest has also been reported further the time delay between the occurrences of the day maximum eej and the well developed eia is studied and corresponding results are presented in this paper

investigation on the variability of the geomagnetic daily current during sudden stratospheric warmings the magnetic field records of the magnetometer networks in the american east asian australian and european african sectors were employed in this present work we used them to investigate equatorial electrojet eej counter electrojet cej tidal variability in eej strength and ionospheric current during the 2005 2006 and 2008 2009 sudden stratospheric warming ssw events in addition to the well investigated tidal variability in eej strength over the american and east asian sectors we investigated that of the african sector for the first time interestingly the tidal components in eej strength during both ssw events clearly exhibit marked longitudinal differences with high moderate and low amplitudes in the american east asian and african sectors respectively an exception found around day 71 in the african sector after the 2008 2009 ssw event had higher solar diurnal tidal component as compared to that of the asian sector over the american sector solar and lunar semidiurnal tides were strongly associated with cej current during both ssw events whereas at the african and east asian sectors such variabilities are not evident a solar diurnal tidal component was strongly related to a reduction in the eej strength over the east asian sector in addition a prolonged period of cej occurrence that begins during the ssw precondition and ends when the ssw was evolving characterized the african sector during both ssw events there is a steady shift in phase at later hours when both ssw events are evolving

detection by infrared thermography and modelling of an icecapped geothermal system in kerguelen archipelago abstract in order to investigate the geothermal fields in the volcanic islands of kerguelen south indian ocean and taking account of the difficult field and meteorological conditions an infrared survey was conducted by a helicopter borne thermocamera on the slopes of the recent volcano of the rallier du baty peninsula where fumaroles were previously found four active zones were observed fumaroles and hot water springs are located near the limits of the icecap which covers all the upper part of the peninsula joint infrared and normal tv imageries have been largely sufficient to obtain detailed surveys of these active zones a tentative model of the icecapped geothermal system has been drawn the main feature being that the supply of convective heat from the recent and still warm magmatic chamber is too low and local for melting all the icecap but remains high enough to insure its slow fusion and the discharge of steam and hot water at its periphery

volcano surveillance using infrared cameras abstract volcanic eruptions are commonly preceded accompanied and followed by variations of a number of detectable geophysical and geochemical manifestations many remote sensing techniques have been applied to tracking anomalies and eruptive precursors and monitoring ongoing volcanic eruptions offering obvious advantages over in situ techniques especially during hazardous activity whilst spaceborne instruments provide a distinct advantage for collecting data remotely in this regard they still cannot match the spatial detail or time resolution achievable using portable imagers on the ground or aircraft hand held infrared camera technology has advanced significantly over the last decade resulting in a proliferation of commercially available instruments such that volcano observatories are increasingly implementing them in monitoring efforts improved thermal surveillance of active volcanoes has not only enhanced hazard assessment but it has contributed substantially to understanding a variety of volcanic processes drawing on over a decade of operational volcano surveillance in italy we provide here a critical review of the application of infrared thermal cameras to volcano monitoring following a summary of key physical principles instrument capabilities and the practicalities and methods of data collection we discuss the types of information that can be retrieved from thermal imagery and what they have contributed to hazard assessment and risk management and to physical volcanology with continued developments in thermal imager technology and lower instrument costs there will be increasing opportunity to gather valuable observations of volcanoes it is thus timely to review the state of the art and we hope thereby to stimulate further research and innovation in this area

δ 18 o records in water vapor and an ice core from the eastern pamir plateau implications for paleoclimate reconstructions this study is the first to examine 18o in daily water vapor at taxkorgan on the eastern pamir plateau the results show that changes in observed and simulated 18o values in water vapor precipitation at the event scale using a lmdz iso model were mainly affected by temperature the influences of humidity precipitation amount and different moisture sources such as the westerlies local evaporated moisture and polar air masses on 18o values are comparatively weak the combination of the 18o record from the muztagata ice core 58 km away from the study area and the lmdz iso simulated annual 18o pattern in precipitation at taxkorgan also demonstrated that temperature and particularly the temperature of the regions over which the southern branch of the westerlies flows is the most important factor controlling 18o variations the results from this study area which is dominated by the westerlies throughout the year are markedly different from those derived from parts of the tibetan plateau that are dominated by the combined influences of the westerlies in winter and the indian monsoon in summer the results suggested that the eastern pamir plateau is an ideal location to reconstruct past temperature variations and that the 18o records preserved in ice cores from the region are a suitable and robust proxy for temperature

upper atmosphere wind systems during reverse equatorial electrojet events days of reversed equatorial electrojet were identified at trivandrum india and in order to seek a global wind change in the dynamo region responsible for these events upper atmosphere winds at a height of 99 km at saskatoon canada were examined during northern winter and also in april and september the reversed electrojets were accompanied by reversals of the eastward wind at saskatoon the winter events generally occurred during a stratwarm no changes in the winds were detected during summer reversed electrojets

the comparative importance of de3 se2 and spw4 on the generation of wavenumber 4 longitude structures in the low latitude ionosphere during september equinox 1 numerical simulations are performed to investigate the generation of the wave 4 longitude variation in the low latitude ionosphere due to the diurnal eastward propagating nonmigrating tide with zonal wavenumber 3 de3 semidiurnal eastward propagating nonmigrating tide with zonal wavenumber 2 se2 and stationary planetary wave 4 spw4 from a fixed local time perspective the de3 se2 and spw4 all appear as wave 4 structures in longitude and thus each of these waves must be considered as a potential source of the wave 4 variation in the ionosphere both thede3 and spw4 are found to produce significant wave 4 variations in the equatorial verticale bdrift velocity and in the ionospheric peak density nmf2 at 15 n magnetic latitude the daytime wave 4 variation in nmf2 is driven by the combination of verticale bdrift variability and in situ effects due largely to meridional neutral winds the simulation results indicate that these2 is not a contributor to the wave 4 longitude variation our results further demonstrate that the actual wave 4 longitude variation is due to a combination of thede3 and spw4 we therefore conclude that in addition to the de3 the spw4 also needs to be considered as an important driver of the wave 4 longitude variation in the low latitude ionosphere we additionally present evidence for the generation of thespw4 due to the nonlinear interaction between the migrating diurnal tide and the de3 and demonstrate the impact of de3 variability on the amplitude of the spw4

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

longitudinal and interhemispheric ionospheric response to 2009 and 2013 ssw events in the african european and indian east asian sectors

hydrogen and oxygen isotopic compositions of water vapor over the bay of bengal during monsoon 1 dv and 18ov of 70 water vapor samples collected at 6 and 25 m above sea level over the bay of bengal bob during july august 2012 are reported this helps characterize the isotopic signature of monsoon vapor no significant vertical variation is observed in dv 18ov or deuterium excess defined as d 8 18o dv and 18ov are significantly correlated r 0 92 at each height the deuterium excess values do not because the variation of dv and 18ov relative to their uncertainties is much larger than that of the latter the temporal variations of dv and 18ov correlate well with air temperature rather than sea surface temperature the control of normalized humidity on deuterium excess is less prominent while the distribution of water vapor isotopologues over the bob is primarily determined by the ocean surface conditions they are significantly altered by laterally advected vapor from rain en route during the monsoon

mass and heat flux balance of la soufriere volcano guadeloupe from aerial infrared thermal imaging abstract la soufriere of guadeloupe is an active volcano of lesser antilles that is closely monitored due to a high eruptive hazard potential since 1992 it exhibits a medium level but sustained background hydrothermal activity with low energy and shallow seismicity hot springs temperature increase and high flux acidic gas fumaroles at the summit the problem of estimating the heat balance and quantifying the evolution of hydrothermal activity has become a key challenge for surveillance this work is the first attempt of a global mapping and quantification of la soufriere thermal activity performed in february 2010 using aerial thermal infrared imagery after instrument calibration and data processing we present a global map of thermal anomalies allowing to spot the main active sites the summit area including the fumaroles of tarissan pit and south crater the ty fault fumarolic zone and the hot springs located at the vicinity of the dome in a second step we deduce the mass and the energy fluxes released by the volcano in particular we propose a simple model of energy balance to estimate the mass flux of the summit fumaroles from their brightness temperature and size in february 2010 tarissan pit had a 22 8 8 1 kg s 1 flux 1970 704 tons day 1 while south crater vents had a total of 19 5 4 0 kg s 1 1687 348 tons day 1 once converted into energy flux summit fumaroles represent 98 of the 106 30 mw released by the volcano the 2 remaining being split between the hot springs and the thermal anomalies at the summit and at the ty fault fumarolic zone these values are in the high range of the previous estimations highlighting the short term variability of the expelled fluxes such a heat flux requires the cooling of 1500 m 3 of magma per day in good agreement with previous geochemical studies

short term variability in the dates of the indian monsoon onset and retreat on the southern and northern slopes of the central himalayas as determined by precipitation stable isotopes this project launched the first study to compare the stable isotopes 18o and d in daily precipitation at kathmandu located on the southern slope of the central himalayas and tingri located on the northern slope the results show that low 18o and d values of summer precipitation at the two stations were closely related to intense convection of the indian monsoon however summer 18o and d values at tingri were lower than those at kathmandu a result of the lift effect of the himalayas coupled with convection disturbances and lower temperatures at tingri in winter the relatively high 18o and d values at the two stations appears to have resulted from the influence of the westerlies compared with those during the summer the subsidence of the westerlies and northerly winds resulted in relatively high 18o and d values of the winter precipitation at tingri winter 18o and d values at kathmandu far exceeded those at tingri due to more intense advection of the southern branch of the westerlies and higher temperatures and relative humidity at kathmandu the detailed differences in stable isotopes between the two stations follow short term variability in the onset date of the indian monsoon and its retreat across the central himalayas during the sampling period the indian monsoon onset at tingri occurred approximately 1 week later than that at kathmandu however the retreat at tingri began roughly 3 days earlier clearly the duration of the indian monsoon effects last longer at kathmandu than that at tingri our findings also indicate that the india monsoon travels slowly northward across the central himalayas due to the blocking of the himalayas but retreats quickly

practical evaluation of steady heat discharge from dormant active volcanoes case study of vulcarolo fissure mount etna italy abstract from a theoretical approach combined with experimental study i propose a method to compute both sensible and latent heat transfer in a thermally active volcanic area this method is applied to a fumarolic thermal fissure located on the south flank on mount etna italy the method involves four steps 1 mapping of self potential sp to quickly identify thermal anomalies 2 mapping of ground temperature t at constant depth in the area defined by sp mapping 3 measurement of vertical t profiles at selected representative stations including the coldest and hottest and 4 direct measurements of vapor flow where the convective heat flux reaches the surface when heat flux values vary in the range 10 300 w m 2 t measurements at a depth equal to about 1 m are sufficient to estimate the absolute flux value to within an absolute error less than 30 and 10 for the relative value ground temperature measurement is an easy and accurate method for estimating heat discharge on a limited surface to define the fissure system monitor time variations of heat flux or to calibrate remote sensing results on the ground

he n and c isotopes and fluxes in aira caldera comparative study of hydrothermal activity in sakurajima volcano and wakamiko crater kyushu japan abstract we investigate the degassing activity of an active submarine crater wakamiko and an active sub aerial volcano sakurajima both located in aira caldera southern kyushu japan we provide 3he 4he 13c co2 and 15n data for 15 hot springs wells and bubbling gas from sakurajima volcano along with 3he 4he from seawater at four different sites for both kagoshima bay and wakamiko crater we find a common magmatic 3he 4he ratio for sakurajima and wakamiko 7 2 0 8 ra which is consistent with 1 a mixing between air saturated water asw and morb type he and 2 a common magmatic source located in the center of aira caldera corrected 3he 4he 13c co2 and ch4 3he data for sakurajima are correlated with the distance from the volcanic vent showa crater which we attribute to crustal contamination and biogenic reaction the low 13c co2 values 10 1 0 2 to 13 7 0 3 observed at sakurajima may result from the addition of carbon from organic matter from basement rocks in magmatic source after correction for air derived nitrogen we find 15nc values range between 1 7 and 4 3 which indicates that magmatic n is dominated by a sedimentary derived component up to 65 8 we calculate wakamiko fluxes of 4he 975 228 mol y 3he 0 011 0 003 mol y co2 184 43 t d and heat 195 22 mw our helium and heat fluxes are the first in situ fluxes ever reported for wakamiko crater all these wakamiko fluxes are at least one order of magnitude lower than those observed for sakurajima co2 1800 t d 3he 0 71 mol y heat 2100 mw degassing at sakurajima volcano is much stronger than that at wakamiko crater the variation of sakurajima co2 flux with time source minamidake or showa crater and eruptive activity appears not to significantly affect the co2 flux at wakamiko crater which is much more stable 132 307 t d during the last 30 years this indicates that there is no link between sakurajima and wakamiko degassing activity despite having the same magmatic source

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

the influence of nonmigrating tides on the longitudinal variation of the equatorial electrojet 1 the climatological model of the equatorial electrojet eejm 1 derived from orsted champ and sac c satellite measurements provides the opportunity to investigate the longitudinal variation of the current strength in detail special emphasis is put in this study on the effect of nonmigrating tides we have found that the influence of the diurnal eastward propagating mode with wavenumber 3 de3 is particularly strong in polar orbiting satellite observations the de3 tidal signal appears as a four peaked longitudinal structure we have put special emphasis in our analysis to isolate the de3 contribution from other sources contributing to the wavenumber 4 structure in satellite data the amplitude of the de3 signature in the eej not only peaks during equinox seasons but is also strong around the june solstice when looking at the modulation of the eej intensity the de3 accounts for about 25 during the months of april through september it is thus the dominant cause for longitudinal variations during december solstice months the influence of de3 is negligible a secondary three peaked longitudinal pattern emerges during solstice seasons when the de3 influence is removed from the data available it is however not clear whether this pattern is related to any tidal drivers