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

observations of the diurnal tide in the mesosphere and lower thermosphere over christmas island atmospheric tidal variations in the mesosphere wind field have been studied extensively using radars most of the climatological studies of the tide have been done at middle and high latitudes previous tropical observations of the diurnal oscillation derived from campaign studies have shown the dominance of the migrating diurnal tide in the mesosphere and lower thermosphere by using wind measurements obtained with a meteor radar system located at christmas island the diurnal tidal behavior in the upper atmosphere of the equatorial pacific has been characterized over several years the data collected from august 1988 to december 1993 are presented in this paper and compared to various model results our observations show the meridional wind component of the diurnal tide maximizes in april near 94 km the observed meridional vertical wavelengths are large and indicate upward propagating energy even though the vertical wavelengths for the zonal diurnal component are also large the phase progression is upward corresponding to downward propagating energy there is considerable interannual and intraseasonal variation in the diurnal amplitudes throughout the year

observations of the two day wave in windii data during january 1993 analysis of variations in the zonal and meridional wind observed by the wind imaging interferometer windii on the upper atmosphere research satellite uars from january 19 to january 31 1993 reveal a strong quasi two day wave qtdw signature these observations were taken during the time of peak amplitude for this qtdw event wu et al 1993 and extend from 41 n to 71 s daytime and nighttime results are presented for the altitude ranges 90 to 150 km and 90 to 102 km respectively the qtdw is found to occur with significant amplitude well into the winter hemisphere and lower thermosphere its latitudinal structure below 103 km is found to be similar to that calculated by hagan et al 1993 using the background wind profile of portniagin and solov yeva 1992 the peak amplitude occurs at 94 km with a magnitude of about 50 m s for the meridional wind and 30 m s for the zonal wind mean profiles from the summer midlatitudes show a secondary maximum in amplitude near 115 km and a node at 130 km above 130 km the wave appears to be evanescent

global ray tracing simulations of the saber gravity wave climatology 1 since february 2002 the saber sounding of the atmosphere using broadband emission radiometry satellite instrument has measured temperatures throughout the entire middle atmosphere employing the same techniques as previously used for crista cryogenic infrared spectrometers and telescopes for the atmosphere we deduce from saber v1 06 data 5 years of gravity wave gw temperature variances from altitudes of 20 to 100 km a typical annual cycle is presented by calculating averages for the individual calendar months findings are consistent with previous results from various satellite missions based on zonal mean saber data for july and zonal mean gw momentum flux from crista a homogeneous and isotropic launch distribution for the grograt gravity wave regional or global ray tracer is tuned the launch distribution contains different phase speed mesoscale waves some of very high phase speed and extremely low amplitudes as well as waves with horizontal wavelengths of several thousand kilometers global maps for different seasons and altitudes as well as time series of zonal mean gw squared amplitudes based on this launch distribution match the observations well based on this realistic observation tuned model run we calculate quantities that cannot be measured directly and are speculated to be major sources of uncertainty in current gw parameterization schemes two examples presented in this paper are the average cross latitude propagation of gws and the relative acceleration contributions provided by saturation and dissipation on the one hand and the horizontal refraction of gws by horizontal gradients of the mean flow on the other hand

the role of ocean atmosphere reorganizations in glacial cycles abstract a case is made that glacial to interglacial transitions involve major reorganizations of the ocean atmosphere system such reorganizations constitute jumps between stable modes of operation which cause changes in the greenhouse gas content and albedo of the atmosphere only in this way can the rapidity of glacial terminations the hemispheric synchroneity and symmetry of mountain glaciation and the large polar air temperature and dustiness variations be accounted for if these reorganizations are driven in some fashion by orbitally induced seasonal insolation changes then the connection between insolation and climate is most likely through impacts of fresh water transport on the ocean s salinity distribution

diurnal nonmigrating tides from timed doppler interferometer wind data monthly climatologies and seasonal variations 1 timed doppler interferometer tidi measurements of zonal and meridional winds in the mesosphere lower thermosphere are analyzed for diurnal nonmigrating tides june 2002 to june 2005 climatologies of monthly mean amplitudes and phases for seven tidal components are presented at altitudes between 85 and 105 km and latitudes between 45 s and 45 n westward propagating wave numbers 2 3 and 4 the standing diurnal tide and eastward propagating wave numbers 1 2 and 3 the observed seasonal variations agree well with 1991 1994 uars results at 95 km comparisons between the tidi results and global scale wave model gswm and thermosphere ionosphere mesosphere electrodynamics general circulation model time gcm tidal predictions indicate that the large eastward propagating wave number 3 amplitude is driven by tropical tropospheric latent heat release alone in contrast latent heating and planetary wave migrating tidal interactions are equally important to westward 2 and standing diurnal tidal forcing there is good quantitative agreement between tidi and the model predictions during equinox but the latter tend to underestimate the westward 2 and standing diurnal tide during solstice neither model reproduces the observed seasonal variations of the eastward propagating components

mesospheric planetary waves at northern hemisphere fall equinox northern hemisphere planetary waves are strong in the winter and weak in the summer and they go through a fast transition around equinox this transition is studied here using ncar thermosphere ionosphere mesosphere electrodynamics general circulation model time gcm simulations with 1997 national centers for environmental prediction ncep analysis the planetary wave variability during the transition and its effect on the temperature and winds in the mesosphere are examined the simulated planetary wave structure agrees with climatological studies and the fast transition of the planetary waves is captured by the model the wave variability produces large temperature changes in the upper atmosphere above local stations in middle and high latitudes the qualitative behavior of the model is in excellent agreement with recent observations of a major perturbation in oh mesospheric temperatures from ft collins taylor et al 2001 although the smaller calculated magnitude suggests that the planetary wave amplitude might be underestimated by the model

the seasonal variation of the propagating diurnal tide in the mesosphere and lower thermosphere part i the role of gravity waves and planetary waves abstract the seasonal variation of the propagating diurnal tide in the mesosphere and lower thermosphere is examined using results from a 2 yr simulation of the extended version of the canadian middle atmosphere model cmam the cmam is shown to be able to reproduce not only the observed semiannual amplitude variation of the tide in the lower thermosphere but also more subtle features such as amplitude maxima that are stronger in march april than in september october a 4 to 6 h shift in phase between winter and summer in the northern hemisphere and a weaker seasonal variation of phase in the southern hemisphere part i of this two part series of papers investigates the importance of two of the mechanisms that have been proposed to explain the observed variation of tidal amplitude namely 1 interactions with small scale gravity waves and 2 interactions with planetary scale waves like the quasi 2 day wave analysis of the tidal momentum and thermodynamic budgets shows that the direct effects of param

seasonal and longitudinal variations of the solar quiet sq current system during solar minimum determined by champ satellite magnetic field observations 1 vector magnetometer observations from the challenging minisatellite payload champ satellite are used to determine the solar quiet sq current system during the recent solar minimum observations from 2006 to 2008 are combined and after removal of a main field model and accounting for field aligned currents the longitudinal and seasonal variation of the sq currents are determined through the method of spherical harmonic analysis comparison with sq currents derived from ground based magnetometers in the african european longitude sector reveals similar amplitudes and seasonal variations indicating that the champ observations can reliably determine the sq current system the seasonal variation is consistent with prior observations during solar minimum conditions and in the northern hemisphere exhibits a primarily annual variation with peak currents during local summer the seasonal variation in the southern hemisphere is characterized by a semiannual variation with the maxima occurring around the equinoxes significant longitudinal variations are also observed and they display a seasonal variability during northern hemisphere summer the predominant feature at local noon is a wave number 1 variation in longitude during the remainder of the year a wave 3 longitudinal structure is observed at this local time the longitudinal variations are considered to be due to a combination of the orientation and strength of the geomagnetic field as well as the tidal winds in the lower thermosphere variations in tidal winds due to nonmigrating tides may influence the dynamo generated electric fields and currents resulting in the observed longitudinal variations of the sq current function

long term variability in the equatorial middle atmosphere zonal wind the high resolution doppler imager hrdi on the upper atmosphere research satellite uars has provided measurements of the horizontal wind field in the stratosphere mesosphere and lower thermosphere since november 1991 this data set which spans a period of more than 3 years has facilitated an investigation of the long term behavior of the background circulation on a nearly global basis at middle and high latitudes the zonal circulation is characterized by an annual oscillation at low latitudes 30 the most prominent long term variation above the stratopause is the mesosphere semiannual oscillation msao which maximizes near the equator at an altitude of between 80 and 85 km further analysis of the time series reveals an additional strong variation with an amplitude near 30 ms 1 and a period of about 2 years this feature shows the same altitude and latitude structure as the msao and exhibits a phase relationship with the stratospheric quasi biennial oscillation qbo observations from the christmas island mf radar 2 n 130 w confirm the presence of this mesospheric qbo mqbo these observations support recent findings from a modeling study which generates an mqbo via the selective filtering of small scale gravity waves by the underlying winds they traverse

mesospheric momentum flux studies at adelaide australia observations and a gravity wave tidal interaction model abstract we present here the results of an analysis of gravity wave momentum fluxes in the mesosphere and lower thermosphere inferred using a dual beam doppler radar near adelaide australia during june 1984 our analysis reveals that over 70 of the momentum flux and of the inferred zonal drag was due to gravity waves with observed periods less than one hour this suggests that it is the gravity waves with high intrinsic frequencies and small horizontal scales that are most effective at transporting momentum into the middle atmosphere the temporal variations in the momentum flux and flux divergence due to high frequency motions were also examined in detail in addition to daily variability a strong diurnal modulation was observed to occur this was found to be correlated with the phase of large amplitude diurnal tidal motions as a result of these observations a gravity wave tidal interaction model was proposed which accounts for all of the major features of the observed data including a reduction i

tectonics of marion and prince edward volcanoes indian ocean result of regional control and edifice dynamics abstract a structural analysis of marion and prince edward islands shows two kinds of tectonic control 1 1 regional tectonics the parallelism between a common structural trend on these two islands characterized by a n20 e and e w association the morphology of the underlying submarine plateau the structure of the sea floor and the fact that both islands display the same rhythm of activity all suggest that these volcanoes all resulted from the reactivation of oceanic lithosphere paleostructures 2 2 edifice tectonics the marion cone is better suited for a study of edifice dynamics than prince edward volcano of which about 80 has subsided below sea level marion is composed of a main volcanic center and a rift zone on which a second volcanic center developed it is proposed that the weight of the edifice and the geometry of the feeding and intrusive system emanating from small relatively deep magma chambers are responsible for the peculiar dynamic properties of the marion edifice the latter are the absence of a caldera a low rate of activity and numerous flank landslides a three fold classification of the stability of volcanoes based on structural patterns is proposed

the quasi 2 day wave and spatial temporal variability of the oh emission and ionosphere 1 the quasi 2 day wave qtdw during january 2006 is investigated using sounding of the atmosphere using broadband emission radiometry saber observations of oh airglow and temperature in the mesosphere and lower thermosphere mlt and champ in situ electron density observations at an altitude of 360 km the zonal structure of the qtdw during early 2006 in the southern hemisphere mlt and low latitude ionosphere is dominated by westward propagating zonal wave number 3 w3 and eastward propagating zonal wave number 2 e2 components however the observed longitude variability is not fully described by the e2 and w3 components of the qtdw the remaining longitude variability is attributed to the presence of nonmigrating tides and secondary waves generated by the nonlinear interaction of the qtdw with migrating tides the nonmigrating tides are a combination of those that are generated in situ by qtdw tide nonlinear interactions and those of tropospheric origin that propagate upward into the mlt the results presented demonstrate that nonmigrating tides and secondary waves are of considerable importance for determining the total longitude variability during periods of enhanced qtdw activity the general similarity between the qtdw in oh airglow and temperature indicates that variations in atomic oxygen concentrations due to vertical winds during the qtdw are the primary driver of the qtdw in the oh airglow emission however there are some differences in the oh airglow and temperature that we consider to be connected to changes in eddy diffusion due to changes in gravity waves during the qtdw last although similar zonal structure of the qtdw is observed in the ionosphere the observed longitude variations are not well represented by the qtdw components indicating that nonmigrating tides play a critical role in determining longitudinal variability in the ionosphere during the qtdw the importance of nonmigrating tides in the ionosphere may be related to the relative efficiency of the qtdw and different nonmigrating tides in the generation of electric fields

contrasting types of surtseyan tuff cones on marion and prince edward islands southwest indian ocean ten surtseyan tuff cones on marion island 46 54 s 37 46 e and seven on prince edward island 46 38 s 37 57 e were erupted on shallow submerged coastal plains related to normal faulting they range from pleistocene to holocene in age and exhibit a variable degree of erosion by the sea fundamental differences irrespective of age exist between two types type i cones have diameters of 1 1 5 km rim heights of about 200 m and steep 27 outer slopes deposits are plastered against nearby cliffs beds are thin including layers of accretionary lapilli and less than 10 lithic clasts numerous bomb sags soft sediment deformation structures and gravity slides occur on one of these cones mudflows formed small tunnels which resemble lava tubes associated with channels sometimes having oversteepened walls these cones reflect comparatively low energy conditions and probably resulted from extremely wet surges interspersed with mudflows and ballistic falls type ii cones have smaller diameters 0 5 km but widespread fallout surge aprons rim heights are about 100 m and average slope angles are 18 bedding is massive with variable lapilli matrix ratio and more than 10 lithic clasts without bomb sags these cones formed under drier perhaps hotter and more violently explosive conditions than type i though not as energetic as the phreatomagmatic eruptions of terrestrial tuff rings the two types of surtseyan eruptions are explained by invoking not only different water magma ratios in the conduit but also different mechanisms of water magma interaction the slurry model of kokelaar is favoured for type i and a fuel coolant model for type ii the decisive factor is considered to be rate of effusion with rim closure and exclusion of sea water playing a secondary role

effects of tropospheric wind shear on the spectrum of convectively generated gravity waves abstract the authors examine the effects of tropospheric wind shear on the phase speed spectrum of gravity waves generated by tropical convection a two dimensional cloud resolving model is used to perform numerous squall line simulations with the vertical shear of the horizontal wind varied in three layers of the troposphere several simplified simulations using prescribed heating are also performed to elucidate the interactions of wind shear with thermal forcing it is found that the dominant phase speed range of convectively generated stratospheric gravity waves is primarily determined by the vertical scale of the tropospheric heating and is then modified by the tropospheric wind the gravity wave spectrum is especially sensitive to shear in the upper troposphere through a mechanism similar to critical level filtering such shear acts to reduce the momentum flux of waves propagating in the same direction as the storm relative mean wind through interaction with convective turrets shear in the upper t

nonmigrating diurnal tides in mesospheric and lower thermospheric winds and temperatures abstract this paper presents analyses of nonmigrating diurnal tide signatures in high resolution doppler imager mesospheric and lower thermospheric winds and temperatures a global comparison of both winds and temperature reveals equatorial features corresponding to nonmigrating tides structures interpreted as zonal mean and eastward nonmigrating diurnal tides display consistency between horizontal winds and temperatures the second symmetric mode is prominent in the zonal mean and wavenumber 1 the gravest antisymmetric mode and the gravest symmetric or kelvin mode are the main features in zonal wavenumbers 2 and 3 the amplitudes of the tides generally increase with altitude and maximize within 90 110 km

direct observations of nonmigrating diurnal tides in the equatorial thermosphere 1 we present direct observations of nonmigrating diurnal tides in the 90 270 km range inferred from the upper atmosphere research satellite uars wind imaging interferometer windii a prominent zonal wavenumber 4 appears in daytime zonal winds extending to 180 km we interpret this signature as an eastward propagating diurnal wavenumber 3 de3 viewed from the satellite perspective this evidence of the extended upward propagation of de3 demonstrates that it acts as a direct coupling agent between the troposphere and the thermosphere and f region in addition to its role in the e region dynamo

nonmigrating semidiurnal tide over the arctic determined from timed doppler interferometer wind observations received 25 june 2009 revised 30 october 2009 accepted 5 november 2009 published 30 march 2010 1 the timed doppler interferometer tidi on the nasa thermosphere ionosphere mesosphere energetics and dynamics timed satellite has been measuring horizontal winds in the mesosphere and lower thermosphere mlt since 2002 because of the high inclination of the timed orbit tidi measures the horizontal winds from pole to pole every orbit this paper presents the first assessment of the spatial structure and temporal evolution of the nonmigrating semidiurnal tides over the arctic determined from the tidi wind measurements and a comparison of the structure of the nonmigrating semidiurnal tide between the arctic and antarctic the nonmigrating semidiurnal tides were determined as a 60 day average based on the yaw cycles of the spacecraft the nonmigrating semidiurnal tidal wind field over the arctic comprises mainly the westward propagating zonal wave numbers1 w1 and3 w3 andstandingzonalwavenumber0 s0 modes thew1modeis the most prominent maximizing above 90 km poleward of 60 n during the yaw interval ranging from mid march to mid may while this mode exhibits a slight amplitude increase toward the north pole during this interval its phase is nearly constant with latitude the s0 mode is enhanced over two yaw intervals ranging from mid january to mid may but its amplitude decreases toward the north pole compared to the w1 semidiurnal tide over the antarctic that over the arctic is smaller in amplitude of less extended duration achieves maximum amplitudes at higher altitudes by 10 km and exhibits a weaker amplitude increase toward the pole these differences likely result from differences in excitation mechanisms and efficiency and or in propagation conditions in the two responses for the nonmigrating semidiurnal tides between the arctic and antarctic

field application of calcite dispersed alkaline substrate calcite das for passive treatment of acid mine drainage with high al and metal concentrations abstract passive treatment systems are widely used for remediation of acid mine drainage amd but existing designs are prone to clogging or loss of reactivity due to al and fe precipitates when treating water with high al and heavy metal concentrations dispersed alkaline substrate das mixed from a fine grained alkaline reagent e g calcite sand and a coarse inert matrix e g wood chips had shown high reactivity and good hydraulic properties in previous laboratory column tests in the present study das was tested at pilot field scale in the iberian pyrite belt sw spain on metal mine drainage with ph near 3 3 net acidity 1400 1650 mg l as caco3 and mean concentrations of 317 mg l fe 95 fe ii 311 mg l zn 74 mg l al 20 mg l mn and 1 5 0 1 mg l cu co ni cd as and pb the das tank removed an average of 870 mg l net acidity as caco3 56 of inflow 25 fe 93 al 5 zn 95 cu 99 as 98 pb and 14 cd but no mn ni or co average gross drain pipe alkalinity was 181 mg l as caco3 which increased total fe removal to 153 mg l 48 in subsequent sedimentation ponds unfortunately the tank suffered clogging problems due to the formation of a hardpan of al rich precipitates das lifetime could probably be increased by lowering al loads

satellite observations of mean winds and tides in the lower thermosphere 2 wind imaging interferometer monthly winds for 1992 and 1993 1 satellite observations of monthly i e 60 d averages centered on the 15th of each month zonal mean and migrating tide winds in the region of 90 120 km and 40 s 40 n from the wind imaging interferometer are presented the zonal mean zonal winds are characterized by annually varying eastward winds at midlatitudes with a maximum in summer and semiannually varying westward winds in the tropics with maxima at equinox below 105 km the zonal mean meridional winds are characterized by a summer to winter flow below 100 km at solstice and by a cell like structure at equinox the latter is the first such global observation of this tidally driven structure two distinct types of diurnal tide are observed an upward propagating one and an evanescent one of comparable magnitude the propagating tide which is dominant in the subtropics below about 105 km exhibits a semiannual variation with a primary maximum in march april and a secondary maximum in september october the evanescent tide which is dominant poleward of 20 n s and above 100 km has an annual variation with a maximum in the summer months the coupling of the two produces a double peaked structure in the vertical profile of the diurnal amplitude the semidiurnal tide is generally weaker than the diurnal tide the maximum semidiurnal winds are at 30 40 n s and at 105 110 km both zonal and meridional components are stronger in april september than in october march in both hemispheres but in the equatorial region in april september the meridional component has a maximum whereas the zonal component has a minimum

observations of the 6 5 day wave in the mesosphere and lower thermosphere previous observations of atmospheric oscillations with zonal wave number 1 have consistently located waves of periods between 5 and 7 days this study presents a global and seasonal analysis of the 6 5 day wave in high resolution doppler imager daytime mesosphere and lower thermosphere horizontal winds temperatures and nighttime atomic oxygen at 95 km the horizontal structures of all these atmospheric variables are similar to the gravest symmetric wave number 1 rossby wave i e the 1 1 mode the seasonal and spatial analysis displays possible modification by the zonal mean wind finally the observed vertical structures of the 6 5 day wave indicate that it is an internal rossby wave not an external or lamb wave

solar tides as revealed by measurements of mesosphere temperature by the mls experiment on uars abstract temperatures between 25 and 86 km measured by the microwave limb sounder mls experiment on the upper atmosphere research satellite uars are analyzed to delineate diurnal semidiurnal and terdiurnal tidal structures and stationary planetary waves these fourier components are determined from temperatures averaged in bins covering 5 latitude 30 longitude and 1 h in local time this study confirms the presence of diurnal nonmigrating tides with zonal wavenumbers s 0 2 3 s 0 s 0 implying westward eastward propagation and semidiurnal tides with s 1 and 3 and some components of lesser importance that were previously determined from uars wind measurements near 95 km the seasonal latitudinal and height structures of these components are now revealed and utilized to aid in interpreting their behaviors and ascertaining their origins new discoveries include the terdiurnal s 2 and s 4 components and trapped nonmigrating diurnal tides with s 0 and s 2 the former are like

observations of a nonmigrating component of the semidiurnal tide over antarctica 1 data obtained from the mf radars situated at davis syowa and rothera in antarctica are used to detect a nonmigrating component of the semidiurnal tide in the mesosphere and lower thermosphere these radars are at similar latitudes and so share a common migrating tidal component by fitting semidiurnal tide vectors to each stations data and performing subtractions of these vectors for pairs of stations the migrating component can be removed and the difference between the nonmigrating components revealed non zero differences in the summer months december to march indicate the presence of a significant nonmigrating component modeling studies and observations at other sites suggest that it is most likely the westward propagating wavenumber 1 nonmigrating component that is contributing to the semidiurnal tide the data presented here are found to be consistent with this hypothesis a climatology of this nonmigrating component is presented and discussed comparisons with the global scale wave model suggest that latent heat release is not a significant forcing mechanism at these heights and latitudes

on modeling migrating solar tides recent updates and extensions to a steady state two dimensional linearized model of global scale atmospheric waves have facilitated improved calculations of the subset of those waves which are subharmonics of a solar day and propagate with the apparent motion of the sun the model improvements are briefly described and some updated predictions of the migrating solar diurnal component are highlighted the latter represent the first numerical modeling effort to examine the seasonal variability of the migrating diurnal harmonic as it propagates into the mesosphere and lower thermosphere

madagascar basalts tracking oceanic and continental sources extensive upper cretaceous volcanism in southern madagascar was fed in part by mantle sources resembling those expressed today in the indian ocean at marion and prince edward islands and on the central southwest indian ridge in addition very low end t to 17 4 high 87sr 86sr t to 0 72126 tholeiites in southwestern madagascar were variably but highly contaminated by ancient continental material broadly like that affecting the bushe and poladpur formations of the later deccan traps in india alkalic dikes in southwestern madagascar have a rough analogue in the mahabaleshwar formation of the deccan in that they document the influence of a low 206pb 204pb negative end relatively low 87sr 86sr reservoir a very similar reservoir is manifested at present in mid ocean ridge basalts on the central southwest indian ridge near 40 e the original location of this end member appears likely to have been in the madagascan lithospheric mantle a portion of which may have been removed in the middle cretaceous by the action of the marion hotspot or the rifting of indo madagascar an origin within the hotspot itself also may be possible however recent products of the hotspot appear to lack completely the necessary low 206pb 204pb low end signatures

tidal signatures and aliasing in temperature data from slowly precessing satellites 1 thermosphere ionosphere mesosphere electrodynamics general circulation model time gcm data are used to simulate tidal patterns in satellite borne observations of the mesosphere and lower thermosphere mlt region the results are given for the measurement geometry of the sounding of the atmosphere using broadband emission radiometry saber instrument though the technique is applicable to any satellite based instrument time gcm tides are sampled along the instrument measurement track and analyzed in terms of ascending descending orbit node differences our simulations show a significant aliasing e g of migrating and nonmigrating diurnal and semidiurnal components into tidal fields of observed zonal wavenumbers s 0 above the mesopause the model tides induce a 10 k bias in daily means of zonally averaged temperatures an estimate of the tide induced vertical displacement of air parcels is given assuming tidal motions are adiabatic corresponding signatures are expected to be present in mlt observations of chemical species addressing tidal sampling issues is of general interest for comparing satellite observations with models climatologies and other measurements

nonmigrating semidiurnal and diurnal tides at 95 km based on wind measurements from the high resolution doppler imager on uars 1 for more than a decade derived results from the high resolution doppler imager hrdi on uars have provided an enormous amount of new and invaluable information on the global variability of atmospheric winds these and other results have given added impetus to theoretical modeling efforts until recent years the large majority of investigations have focused on migrating tides and now more results on nonmigrating tides have become available we provide new results for semidiurnal and diurnal nonmigrating tides based on data from hrdi at 95 km much of these results have not been obtained before and they are substantially different from those that have been previously reported our amplitudes are usually significantly larger with more periodicities in both day of year and latitude than results that have previously appeared in the literature we also find components up to longitude wave number 3 that are significant and have not been presented before and that traveling components of larger longitude wave numbers 4 5 and 6 can reach several m s in amplitude we compare our results with earlier results based on hrdi measurements and from selected models

field multi step limestone and mgo passive system to treat acid mine drainage with high metal concentrations abstract passive treatment systems have become one of the most sustainable and feasible ways of remediating acid mine drainage amd however conventional treatments show early clogging of the porosity or and coating of the reactive grains when high acidity and metal concentrations are treated the performance of fine grained reagents dispersed in a high porosity matrix of wood shavings was tested as an alternative to overcome these durability problems the system consisted of two tanks of 3 m 3 filled with limestone sand and wood shavings and one tank of 1 m 3 with caustic magnesia powder and wood shavings separated by several oxidation cascades and decantation ponds the system treated about 1 5 m 3 day of amd containing an average of 360 mg l fe 120 mg l al 390 mg l zn 10 mg l cu 300 g l as and 140 g l pb a mean ph of 3 08 and a net acidity of 2500 mg l as caco 3 equivalent the water reached ph 5 and 6 in the first and second limestone tanks respectively suitable to remove trivalent metals and ph 8 9 in the mgo tank suitable to remove divalent metals after 9 months of operation the system achieved an average removal of 100 al cu as pb more than 70 fe about 25 zn and 80 acidity goethite schwertmannite hydrobasaluminite amorphous al oh 3 and gypsum were the main precipitates in the two limestone tanks precipitation of divalent metals fe ii zn and traces of cd ni and co were complete inside the third tank of mgo but preferential flow along the walls was responsible for its low treatment performance goethite gypsum zn schulenbergite and sauconite are the crystalline solid phases identified in the mgo tank

susceptibility of mid ocean ridge volcanic islands and seamounts to large scale landsliding 1 with a view to assessing the incidence of large scale landsliding a morphologic database was created for volcanic islands and seamounts on young oceanic lithosphere the database included 44 mid ocean ridge seamounts jasper seamount and the islands of ascension bouvet guadalupe and several of the galapagos and azores islands supplemented with published reports from a further five volcanic edifices the data reveal that major landslides are common on edifices taller than 2500 m but are rare in shorter edifices implying a threshold of instability at around 2500 m a number of causes of this threshold are discussed for example many structures taller than 2500 m are or were originally volcanic islands and therefore their flanks probably include extensive weak hyaloclastite built up from lava sea interactions around coasts compaction of hyaloclastites in larger edifices lead to regions of low permeability which may help to explain the more deeply seated slope failures it is intriguing that the threshold also coincides with the edifice height at which volcanic ridges become observable a stage at which dike intrusion is probably common because slope oversteepening or excess pore pressure associated with dike intrusions have been proposed elsewhere as landslide triggers the current indications of landsliding reveal no observable relation to rainfall as landslides occur equally in wet and dry climates and no relation to tectonic setting as there are relatively few major landslides in the seismically active azores group

tidal gravity wave interactions and their influence on the large scale dynamics of the middle atmosphere model results results from a modified version of the quasi geostrophic model of mclandress and mcfarlane 1993 in combination with the tidal model of forbes 1982a b are used to delineate the role of tides in modulating gravity wave momentum fluxes and the ensuing effects on the large scale circulation of the middle atmosphere for solstice conditions the influence of the tidal wind fields on the location and strength of the gravity wave drag is strongest in the mesosphere and lower thermosphere where the tidal winds are of the same order as the zonal mean component due to the nonlinear dependence on the local wind speed the daily mean gravity wave drag in the model can differ significantly depending on whether or not tidal variations are included at middle and low latitudes these differences are largest and occur as a result of the filtering effects of the shorter vertical wavelength diurnal tide at more polar latitudes where the longer wavelength semidiurnal tide dominates a slight increase in drag occurs the interaction between the tidal wind fields and the localized orographic gravity wave momentum flux has important consequences for the in situ generation of planetary scale disturbances in particular the amplification of stationary planetary wavenumber 1 is enhanced by the presence of tides in addition forcing of nonmigrating tidal modes is predicted to occur as a result of the localized drag

hydrochemical performance and mineralogical evolution of a dispersed alkaline substrate das remediating the highly polluted acid mine drainage in the full scale passive treatment of mina esperanza sw spain acid mine drainage remediation is an unresolved matter in abandoned mining districts around the world development and implementation of passive treatment systems in these areas are commonly focused on engineering and water quality aspects neoformed mineral phases precipitated within the reactive material of these passive treatments account for the removal of pollutants but also can cause clogging and passivation of the reactive substrate after 20 months of operation and monitoring the limestone based passive treatment system implemented in mina esperanza sw spain was sampled to study the relationship between water chemistry mineral composition of the neoformed precipitates and treatment performance water chemical profiles show the existence of three precipitation zones controlled by fe al and zn hydrochemistry and also a migration with time of precipitation zones downward into the reactive material these precipitation zones were also confirmed by a mineral study performed on the solid samples where either schwertmannite and goethite or hydrobasaluminite and zn rich green rust were the mineral phases that controlled the metal removal in the three precipation fe al or zn zones iron and al precipitates were observed to play a critical role in the time evolution of the reactive material hydraulic conductivity furthermore al precipitates passivated to some extent the limestone grains by armoring although migration of the fe precipitation zone and al redissolution later activated the limestone grains a higher proportion of limestone in the reactive mixture and the addition of new reagents to the bottom section of the reactive material to enhance the reducing environment and to promote divalent metal removal are proposed on the basis of this hydrochemical and mineralogical study for a future design for the mina esperanza passive treatment system

msx satellite observations of thunderstorm generated gravity waves in mid wave infrared images of the upper stratosphere data from the midcourse space experiment msx has provided the first observations of thunderstorm generated gravity waves imaged from space gravity wave theory predicts that isolated sufficiently convective thunderstorms can launch waves and create a unique intensity pattern of concentric circles on a radiating surface of constant altitude above such a storm among the msx constant nadir angle mid wave infrared mwir observations two instances of such patterns have been identified it was confirmed from meteorological satellite images that highly convective isolated thunderstorms occurred at the locations and times expected

hotspots in the southern oceans an absolute frame of reference for motion of the gondwana continents abstract the geometry and geochronology of aseismic ridges and oceanic islands in the southern oceans provide a good test of the proposition that hotspots remain fixed over long periods of time that is motion of an order of magnitude less than the relative motion between plate pairs in most cases it is concluded that inter hotspot movement cannot be discerned for the period 100 m y to present and that widely distributed hotspots in the atlantic and indian oceans provide a frame of reference for plate motions following the disintegration of gondwanaland which is independent of paleomagnetism this frame of reference is absolute in that it gives the motion of the lithosphere with respect to the mantle hotspots the absolute motion model indicates that africa and antarctica are now moving only very slowly that there has been significant relative movement between east and west antarctica since the cretaceous and prescribes the relative motion between the somali and african plates

terrestrial and submarine evidence for the extent and timing of the last glacial maximum and the onset of deglaciation on the maritime antarctic and sub antarctic islands this paper is the maritime and sub antarctic contribution to the scientific committee for antarctic research scar past antarctic ice sheet dynamics pais community antarctic ice sheet reconstruction the overarching aim for all sectors of antarctica was to reconstruct the last glacial maximum lgm ice sheet extent and thickness and map the subsequent deglaciation in a series of 5000 year time slices however our review of the literature found surprisingly few high quality chronological constraints on changing glacier extents on these timescales in the maritime and sub antarctic sector therefore in this paper we focus on an assessment of the terrestrial and offshore evidence for the lgm ice extent establishing minimum ages for the onset of deglaciation and separating evidence of deglaciation from lgm limits from those associated with later holocene glacier fluctuations evidence included geomorphological descriptions of glacial landscapes radiocarbon dated basal peat and lake sediment deposits cosmogenic isotope ages of glacial features and molecular biological data we propose a classification of the glacial history of the maritime and sub antarctic islands based on this assembled evidence these include type i islands which accumulated little or no lgm ice type ii islands with a limited lgm ice extent but evidence of extensive earlier continental shelf glaciations type iii seamounts and volcanoes unlikely to have accumulated significant lgm ice cover type iv islands on shallow shelves with both terrestrial and submarine evidence of lgm and or earlier ice expansion type v islands north of the antarctic polar front with terrestrial evidence of lgm ice expansion and type vi islands with no data finally we review the climatological and geomorphological settings that separate the glaciological history of the islands within this classification scheme

observations of 2 dimensional airglow structure and na density from the aloha october 9 1993 storm flight on october 9 1993 observations were made from the ncar electra aircraft during a 7 hour flight towards a tropospheric low pressure system nw of maui a very bright 50 intensity amplitude oh wave 200 km horizontal wavelength was encountered 900 km nw of maui the oh volume weighted na column density measured by the lidar increased 4 fold at the same location oh imagery showed the wave phase front was aligned ne sw similar to the tropospheric airmass boundary which was located 2000 km nw of maui this wall wave had an apparent phase velocity v of 75 ms 1 toward the se and was observed overhead haleakala maui 3 1 4 hours later the wall appeared to represent the southern boundary for an extensive short horizontal wavelength structure with a similar phase front alignment this structure had weak amplitudes initially but was fully developed 1 hour after encountering the wall the details of oh imagery intensity and na structure associated with this event are summarized

climatology of upward propagating diurnal and semidiurnal tides in the thermosphere 1 a major challenge in delineating and understanding the space weather of the ionosphere thermosphere system is the lack of global tidal observations in the 120 400 km thermospheric gap between satellite remote sensing and in situ tidal diagnostics this paper aims to close this gap by presenting an observation based climatological tidal model of the thermosphere ctmt of self consistent upward propagating migrating and nonmigrating diurnal and semidiurnal tides from 80 400 km and pole to pole for moderate f10 7 110 sfu solar flux conditions ctmt includes the 6 8 most important diurnal semidiurnal tidal components for temperature density and zonal meridional and vertical winds and is based on hough mode extension fits to 2002 2008 mean timed satellite tidal diagnostics in the mesosphere lower thermosphere mlt validation with independent 2002 2008 champ tidal diagnostics f10 7 105 sfu around 400 km proves that the approach captures nonmigrating tides well indicating that these waves propagate directly upward without significant tidal forcing occurring in the thermosphere notable exceptions are the dw2 and d0 components that are most likely generated in situ by nonlinear interaction forcing in the upper thermosphere ctmt is suitable for driving upper atmosphere models that require self consistent tidal fields in the mlt region as a lower boundary condition it does not include migrating tides due to in situ euv absorption in the upper thermosphere but allows us to quantitatively assess thermospheric variability due to tides from the lower atmosphere this is done by discussing longitude latitude maps of reconstructed diurnal and semidiurnal tidal variations as function of altitude and local time

global observations of gravity waves from high resolution dynamics limb sounder temperature measurements a yearlong record of temperature amplitude and vertical wavelength 1 global observations of gravity waves have been performed using the high resolution dynamics limb sounder hirdls temperature data a background field that was derived by dynamically calculating 31 day 15 day means to block the stationary component and the slowly varying planetary scale waves was first subtracted from the hirdls temperature measurements an additional step was then taken to remove rapidly moving planetary scale waves by developing an along track temperature filter which was created by averaging the profiles within a 1000 km along track window finally each individual temperature perturbation vertical profile was analyzed using a fast fourier transform to estimate gravity wave temperature amplitudes and vertical wavelengths the investigation of the monthly mean gravity wave temperature amplitudes for the year 2006 found that gravity wave activity in the stratosphere is highly variable with season and can be very orographically dependent especially in the winter extratropics the monthly zonal means show that the peak vertical wavelengths correspond closely to the peak amplitudes the increasing amplitudes and vertical wavelengths are faster and generated at lower altitudes in the winter extratropical and high latitude stratosphere than those in the summer tropical stratosphere this is consistent with the lower source altitudes of orographic gravity waves in the extratropics and high latitudes and the higher source altitudes of convectively generated gravity waves in the tropics three cases were studied for the observed gravity waves over large mountain ranges using the european centre for medium range weather forecasts wind data investigations of episodes of enhanced gravity wave activity over the southern andes the cascade range and the rockies in winter months of 2006 indicate that orographic gravity waves refract downwind from the mountains and propagate along the direction of the intense winds by way of contrast observations of gravity waves around the himalayas show a strong relationship with the cyclones in that region

comparison of champ and time gcm nonmigrating tidal signals in the thermospheric zonal wind 1 four years 2002 2005 of continuous accelerometer measurements taken onboard the champ satellite orbit altitude 400 km offer a unique opportunity to investigate the thermospheric zonal wind on a global scale recently we were able to relate the longitudinal wave 4 structure in the zonal wind at equatorial latitudes to the influence of nonmigrating tides and in particular to the eastward propagating diurnal tide with zonal wave number 3 de3 the de3 tide is primarily excited by latent heat release in the tropical troposphere in deep convective clouds in order to investigate the mechanisms that couple the tidal signals to the upper thermosphere we undertook a comparison with the thermosphere ionosphere mesosphere electrodynamics general circulation model time gcm developed at the national center for atmospheric research ncar we ran the model for a day in march june september and december and applied the same processing steps to the model output as was done for the champ tidal analysis the main results of the comparison can be summarized as follows 1 time gcm simulations do not correctly reproduce the observed intra annual variations of de3 and the eastward propagating diurnal tide with zonal wave number 2 de2 2 simulations of de3 for june are more successful both time gcm and champ show an increase in de3 amplitudes with decreasing solar flux level 3 the amplitudes of the simulated westward propagating diurnal tide with zonal wave number 2 dw2 and the standing diurnal tide d0 increase with increasing solar flux in june the predicted dependence of dw2 and do on solar flux is also observed by champ

rapid deglaciation as an initiator of volcanic activity an hypothesis volcanic activity on sub antarctic marion island is found to have occurred only during the interglacials the present volcano distribution is associated with a radial and peripheral fault system the location of which appears to be related to the former glacier distribution an hypothesis is presented suggesting that the faulting is a result of deglaciation and that the specific location of the faults is due to the differential stresses occurring between ice covered and ice free areas during isostatic uplift the faulting initiates volcanism due to the location of the island within a volcanic region

sources of nonmigrating tides in the tropical middle atmosphere 1 temperature measurements from the cryogenic infrared spectrometers and telescopes for the atmosphere crista experiment taken during the u s space shuttle mission sts 66 in november 1994 provide a variety of zonally symmetric and asymmetric tidal signatures in the altitude range from 40 90 km the most prominent zonally asymmetric tidal pattern is identified to be the westward propagating nonmigrating diurnal tide of zonal wavenumber 2 s 2 this mode has an amplitude of approximately half the amplitude of the migrating s 1 component of the diurnal tide the observational findings are compared to model results from the global scale wave model gswm and from the thermosphere ionosphere mesosphere electrodynamics general circulation model time gcm gswm and time gcm account for different tidal sources and therefore allow an analysis of the tidal forcing responsible for the observed signatures the gswm tidal forcing in the model version used is based upon latent heat release associated with tropical deep convection while nonmigrating tides in the time gcm are predominantly forced by nonlinear interactions between the migrating diurnal tide and stationary planetary waves it is shown that the latter mechanism forces a large part of the s 2 mode while the stationary zonally uniform s 0 diurnal nonmigrating tide is mainly driven by latent heat release this result suggests that dynamical models for the mesosphere lower thermosphere mlt region need to account for the tropospheric latent heat source and stationary planetary wave activity in order to predict realistic longitudinal diurnal tidal variability

brunhes matuyama magnetic reversal dated at 790 000 yr b p by marine astronomical correlations abstract the presence of the brunhes matuyama magnetic reversal in deep sea core sediments makes possible an alternative to the usual k ar radioistope method of dating the reversal as found in rocks the alternative method uses correlations of northern hemisphere summer insolation with oxygen isotope ratios from tropical cores the latitude dependent insolation variations are calculated from planetary mechanics and thus provide a highly accurate astronomical time scale the insolation variations strongly influence glacial ice volume fluctuations that dominate the oxygenisotope ratio changes recorded in core sediments the summer half year insolation variations are identified with corresponding isotope ratio changes in cores from the present through glacial stage 20 misleading effects of discontinuities or major nonuniformities of sediment deposition are avoided by an analysis of the uniformity of v28 238 and v28 239 the principal cores studied and by comparisons with other cores the top section stages 1 to 10 of v28 238 is uniformly deposited and for this section an isotope ratio time scale is chosen that agrees with the thorium uranium date for the high sea stand of the last interglacial extreme over this interval major glacial extremes strong isotope ratio minima coincide consistently with major insolation minima at times of low orbital eccentricity in addition interstadials are directly associated with precessional insolation peaks and the envelope of isotope ratio peaks resembles the envelope of precessionally dominated insolation peaks the assumption that the glacial extremes depended similarly on insolation minima during stages 10 to 20 permits minor age shifts of strong isotope ratio minima in the two cores relative to ages based on uniform overal deposition to match the ages of low eccentricity insolation minima the age shifts reflect residual nonuniformities of deposition the validity of this matching procedure is supported by a resulting consistent identification of principal isotope ratio peaks with high and low latitude coincident insolation maxima the brunhes matuyama reversal is found intinterglacial stage 19 and is dated on the astronomical time scale at 790 000 5000 yr b p

extreme longitudinal disturbances in the mesosphere and thermosphere observed with the wind imaging interferometer on uars 1 extreme longitudinal disturbances in the o 1s emission rate and horizontal winds in the mesosphere and thermosphere 90 180 km are identified on three march days in 1994 1996 and 1997 in the database of the wind imaging interferometer windii on the upper atmosphere research satellite uars this type of disturbance has a wave structure with apparent zonal wavenumber 1 and a very long vertical wavelength it generates longitudinal amplitudes of 70 photons cm 3 s 1 and 120 ms 1 in the o 1s volume emission rate and winds respectively and is strong enough to break the structures of migrating tides in the e region in the same longitudinal zone for day and night the zonal wind driven by this disturbance has the same phase suggesting a wave with s 1 and a very long period but the meridional wind has opposite phases suggesting a standing non migrating diurnal tide this super disturbance has not been observed before and fundamental questions about it await future investigation

first measurements of thermal tides in the summer mesopause region at antarctic latitudes 1 we present the first detection of thermal tides in the middle atmosphere at polar latitudes in summer the iap iron lidar is in operation in davis 69 s 78 e antarctica since december 2011 and measures temperatures in the height range 84 96 km with an accuracy of 1 3 k after 1 hour integration with an effective altitude resolution of 1 km iron densities are observed from 75 140 km we analyze 171 hours of observations in the period 11 28 january 2011 and find strong tidal modulations in fe density and temperatures typical amplitudes of thermal tides are 2 4 k for both the diurnal and semidiurnal component the diurnal tide is larger smaller than the semidiurnal component below above 90 km the phase of the diurnal tide decreases with altitude by 1 3 h km which corresponds to a vertical wavelength of 30 km a similar phase progression is observed in fe densities extending below and above the height range of temperature measurements the overlay of diurnal and semidiurnal components leads to tidal modulations of up to 6 k for temperatures and up to 4000 ccm 40 for fe number densities these modulations are much larger compared to most simulations and point to some missing processes in tidal modeling

k ar geochronology of marion island southern ocean marion island is a youthful intraplate shield volcano in the southern ocean generally considered to represent the location of a mantle plume new k ar age determinations on 37 whole rock samples of so called older grey basalt from the island range from 450 10 to 30 ka the lavas are remarkably fresh and holocrystalline appearing to be ideal for dating the age results from two almost vertical sections where relative age relationships are not in doubt are in accord with the stratigraphy a third section gave aberrant ages that indicate the presence of inherited or excess radiogenic argon this is highly unusual for subaerial flows on an oceanic island we therefore urge caution in accepting k ar ages on samples without stratigraphic control volcanic activity on marion could have been essentially continuous during the last half million years but on the basis of local unconformities and gaps between the measured ages it is considered more likely to have been episodic eight periods of effusive activity at approximately 450 350 240 170 110 85 50 and 10 ka ago can be distinguished with varying degrees of confidence glacigene deposits that are intercalated with the lavas can be correlated with glacial stages 2 4 6 8 and 12 of the pleistocene time scale based on the marine oxygen isotopic record indications are that at least some of the earlier volcanic activity coincided with glacial stages but the two most recent episodes including the holocene one extending up to the present are clearly interglacial

microwave limb sounder observations of gravity waves in the stratosphere a climatology and interpretation high horizontal resolution temperature data from the microwave limb sounder mls are analyzed to obtain information about high intrinsic frequency gravity waves in the stratosphere global climatologies of temperature variance at solstice are computed using six years of data a linear gravity wave model is used to interpret the satellite measurements and to infer information about tropospheric wave sources globally uniform sources having several different spectral shapes are examined and the computed variances are filtered in three dimensional space in a manner that simulates the mls weighting functions the model is able to reproduce the observed zonal mean structure thus indicating that the observations reflect changes in background wind speeds and provide little information about the latitudinal variation of wave sources longitudinal variations in the summer hemisphere do reflect source variations since the modeled variances exhibit much less variation in this direction as a consequence of the zonal symmetry of the background winds a close correspondence between the mls variances and satellite observations of outgoing longwave radiation suggests that deep convection is the probable source for these waves the large variances observed over the tip of south america in winter are most certainly linked to orographic forcing but inferences about wave sources in northern hemisphere winter are difficult to make as a result of the high degree of longitudinal and temporal variability in the stratospheric winds comparisons of model results using different source spectra suggest that the tropospheric sources in the subtropics in summer have a broader phase speed spectrum than do sources at middle latitudes in winter

atmospheric tide 2 the solar and lunar semidiurnal components solar and lunar semidiurnal wind and temperature oscillations from the surface to 400 km are simulated for average solar activity conditions utilizing the numerical tidal model described in part 1 hough mode decomposition of the solstitial solar semidiurnal tide excited by h2o and o3 insolation absorption below 80 km indicates that it is characterized by a predominance of 2 2 below 60 km about equal contributions of 2 2 2 3 and 2 4 between 70 and 90 km mostly 2 4 with some 2 5 and 2 2 between 90 and 120 km and a predominance of 2 2 above 140 km with secondary contributions from 2 3 and 2 5 the solstitial lunar semidiurnal tide is characterized by a predominance of 2 2 below 70 km 2 4 with secondary contributions from 2 2 2 3 and 2 5 between 80 and 110 km and by 2 2 with a fairly strong secondary contribution from 2 3 above 120 km similar descriptions for both the solar and lunar oscillations apply at equinox except that the asymmetric 2 3 and 2 5 modes are absent relative to the solar component lunar temperature and wind amplitudes are sufficiently large 20 in the lower and upper thermosphere to account for some of the observed variability previously attributed to the solar tide amplitudes of the 2 4 and 2 5 modes above 100 km are significantly affected by mesospheric eddy diffusion coefficients in excess of 2 106 cm s 1 the total solar semidiurnal exospheric temperature oscillation for average solar conditions ranges from 10 20 k poleward of 40 n to 40 60 k equatorward of 30 n and has its origin in three sources of excitation all of comparable importance 1 euv solar radiation absorption in the lower thermosphere 100 200 km 2 in situ momentum coupling due to the interaction of diurnal winds and diurnally varying ion drag and 3 tides propagating upwards from below 100 km in addition the calculations are compared with rocket meteor radar partial reflection thomson scatter and satellite data to evaluate the consistency of the model with observations

tidal wind mapping from observations of a meteor radar chain in december 2011 1 this article proposes a technique to map the tidal winds in the mesosphere and lower thermosphere mlt region from the observations of a four station meteor radar chain located at middle and low latitudes along the 120 e meridian in the northern hemisphere a 1 month dataset of the horizontal winds in the altitude range of 80 100 km is observed during december 2011 we first decompose the tidal winds into mean diurnal semidiurnal and terdiurnal components for each station it is found that the diurnal semidiurnal components dominate at the low latitude midlatitude stations their amplitudes increase at lower altitudes and then decrease at higher altitudes after reaching a peak in the mlt region hough functions of the classical tidal theory are then used to fit the latitudinal distribution of each decomposed component the diurnal component is found to be dominated by the first symmetric 1 1 mode yet for the semidiurnal and terdiurnal components the corresponding dominant modes are the second symmetric modes 2 4 and 3 5 and considerable contributions are also from the first antisymmetric modes 2 3 3 4 and second antisymmetric modes 2 5 3 6 based on the decomposed results we further map the horizontal winds in the domains of latitude altitude and local time the mapped horizontal winds successfully reproduce the local time versus altitudinal distributions of the original observations at the four stations thus we conclude that the meteor radar chain is useful to monitor and study the regional characteristics of the tidal winds in the mlt region

metal retention mineralogy and design considerations of a mature permeable reactive barrier prb for acidic mine water drainage in northumberland u k mineralogical characterization of the precipitates developed in passive systems treating mine polluted waters is an essential tool to fully understand and control the removal processes taking place in these systems in 2008 after five years of operation a section of the permeable reactive barrier prb at shilbottle northumberland was subjected to a low intrusive non destructive solid sampling these solid samples were mineralogically characterized by xrd esem eds and sequential extractions in addition to the solid sampling 44 water samples obtained in the prb from january 2004 to august 2009 were used to study the mineral stability of some selected phases in these waters it was observed that the main iron phases in the prb were those associated with mineral phases typically developed in non reducing environments schwertmannite and goethite while the presence of a significant amount of pyrite was also observed the low residence time of the water within the prb from 10 to 40 h appears to be the reason for the absence of a more reducing and less acidic environment in the reactive substrate an increase of residence time in the prb by increasing reactive mixture porosity and resizing the prb changes in the reactive material employed smaller limestone grain size and inclusion of zerovalent iron and changes in the prb design isolating top layer and forced homogeneous flow upward through all the reactive material are proposed for future reconditioning of the system

a global view of the molecular oxygen night airglow 1 the high resolution doppler imager on the upper atmosphere research satellite has observed the o2 atmospheric band nightglow at extremely high spatial resolution of 50 km in the horizontal over much of earth s surface these observations of the oxygen nightglow are shown to be a good surrogate for atomic oxygen outflow from the thermosphere and subsequent recombination in the upper mesosphere the distribution of enhanced airglow and recombination verify the previous observations that bright regions of the nightglow are associated with descending motion where the tides are transporting atomic oxygen out of the thermosphere and regions of decreased airglow are associated with ascending tidal motion the detailed observations of the global airglow at a scale of 100 km present a much more complex picture however the tidally enhanced regions are extremely structured with strong longitudinal and latitudinal variability in brightness and associated atomic oxygen recombination these structured regions are persistent on a timescale of a day or more with certain regions of the globe exhibiting enhanced airglow much of the time these regions are present over the entire night side of the globe but are strongly modulated by the ascending and descending tidal motions a theoretical study of these enhancements suggests that they are caused by the upward propagation of gravity waves which break in the high mesosphere and induce strong vertical motion in the atmosphere it is interesting that the primary cause of the increased transport of atomic oxygen is vertical motion rather than the conventional enhanced turbulence explanation these gravity waves are associated with wind shear and strong convective activity in the troposphere and often appear in certain preferred locations where convective activity is expected these observations have important implications for the basic processes by which momentum and energy are deposited in the upper mesosphere we suggest that the processes must be modeled as stochastic events that dance around the base of the thermosphere generally in climatologically preferred regions rather than the relatively uniform distribution of gravity wave forcings that is being used in general circulation models up to this time

satellite observations of thermospheric tides results from the wind imaging interferometer on uars thermospheric winds measured by the wind imaging interferometer windii on the upper atmosphere research satellite are analyzed for migrating solar tides the data cover a 2 year period commencing february 1992 and are obtained from the atomic oxygen o 1s 557 7 nm emission which provides observations of the 90 to 200 km altitude range during daytime and the 90 to 110 km range at night the subtropical lower thermosphere is dominated by the diurnal propagating tide which exhibits a vertical wavelength of approximately 22 km grows in amplitude up to 95 km and decays rapidly above where molecular diffusion greatly reduces the vertical shears although the phase remains fairly uniform throughout the year a pronounced semiannual oscillation is observed in the diurnal tide amplitude at both 20 n and 20 s the meridional and zonal wind components attain their maximum values at equinox of approximately 70 and 40 m s respectively while the solstitial minima are nearly a factor of 2 smaller at 35 n the diurnal tide semiannual amplitude oscillation is still present in the lower thermosphere but above 100 km it is replaced by an annual cycle with a maximum in july and august this contrasts with 35 s where the july august peak is absent and the semiannual oscillation extends to 110 km at midlatitudes the zonal and meridional winds are of similar magnitude and no significant hemispheric asymmetries in amplitudes are observed in the lower thermosphere the semidiurnal tide amplitude exhibits an annual oscillation with maximum values of 30 to 40 m s occurring in june july near 100 km at 35 n 35 s and the equator a bimodal structure in the seasonal variation of the semidiurnal phase is observed this feature is characterized by rapid equinoctial transitions and is particularly well defined at the equator examination of the equatorial middle thermosphere indicates that the semidiurnal tide attains its maximum amplitude at 140 km and exhibits a vertical wavelength of approximately 60 km these findings indicate the predominance of the antisymmetric 2 3 hough mode in the tropics

diurnal tide in the equatorial middle atmosphere as seen in lims temperatures abstract the distribution of day night temperature differences in the middle atmosphere determined by the nimbus 7 lims experiment is described day night differences maximize at and are approximately symmetric about the equator successive centers of opposite sign increase in amplitude with altitude the pattern having a vertical wavelength of 25 km profiles of rocket meridional wind at kwajalein 8 7 n and ascension island 8 0 s taken near local noon and averaged over the lims data period exhibit maxima which support the tidal interpretation of the equatorial temperature pattern these characteristics are in general agreement with previous observational and theoretical results for the solar driven diurnal tide substantial time variations in amplitude and in location of the temperature maxima are observed the diurnal tide near the equatorial stratopause appears to be influenced by the phase of the semiannual oscillation

separation of tectonic and local components of horizontal gps station velocities a case study for glacial isostatic adjustment in east antarctica accurate measurement of the local component of geodetic motion at gps stations presents a challenge due to the need to separate this signal from the tectonic plate rotation a pressing example is the observation of glacial isostatic adjustment gia which constrains the earth s response to ice unloading and hence contributions of ice covered regions such as antarctica to global sea level rise following ice mass loss while both vertical and horizontal motions are of interest in general we focus on horizontal gps velocities which typically contain a large component of plate rotation and a smaller local component primarily relating to gia incomplete separation of these components introduces significant bias into estimates of gia motion vectors we present the results of a series of tests based on the motions of gps stations from east antarctica 1 signal separation for sets of synthetic data that replicate the geometric character of non separable and separable gia like horizontal velocities and 2 signal separation for real gps station data with an appraisal of uncertainties for both synthetic and real motions we compare results where the stations are unweighted and where each station is areal weighted using a metric representing the inverse of the spatial density of neighbouring stations from the synthetic tests we show that a gia like signal is recoverable from the plate rotation signal providing it has geometric variability across east antarctica we also show that areal weighting has a very significant effect on the ability to recover a gia like signal with geometric variability and hence on separating the plate rotation and local components for the real data assuming a rigid antarctic plate fitted plate rotation parameters compare well with other studies in the literature we find that 25 out of 36 gps stations examined in east antarctica have non zero local horizontal velocities at the 2 level after signal separation we make the code for weighted signal separation available to assist in the consistent appraisal of separated signals and the comparison of likely uncertainty bounds for future studies

tidal signatures in temperature data from crista 1 mission temperature measurements in the stratosphere and mesosphere were taken during the first cryogenic infrared spectrometers and telescopes for the atmosphere crista 1 mission using co2 emissions these measurements range from 13 to close to 100 km and individual temperature measurements have a precision of 1 k the crista orbit was circular at an inclination of 57 so local time variations during the 7 day mission were small for a given latitude and orbit leg zonal averages of the data show significant structure in the vertical and as a function of latitude temperature differences between the zonal mean data from the ascending and descending portions of the orbit are of the form expected from the diurnal tide the maximum zonal mean difference is 20 k and occurs over the equator at an altitude of 75 km zonal variations in the temperature difference indicate that the tidal amplitude is not uniform at all longitudes at the equator the maximum amplitude 30 k appears over the african sector and the minimum 10 k over the pacific sector this variation is most likely a nonmigrating wavenumber 2 diurnal tide although other less plausible possibilities exist to facilitate comparisons with model results the temperature variations are converted to equivalent vertical displacements assuming the tidal motions are adiabatic such an approach is appropriate in the mesosphere where diurnal variations due to radiative effects are small and reduces the dependence of the measured temperature amplitude on the background temperature profile equivalent vertical displacements are also calculated using results from the global scale wave model for the most part the model results and observations are in excellent qualitative and good quantitative agreement from the tropopause to the mesopause however the observed vertical wavelength is smaller and its amplitude in terms of equivalent displacement is smaller in the upper mesosphere than that in the model the decrease in amplitude is consistent with that expected from the transition from equinox to solstice conditions

seasonal variations of mlt tides revealed by a meteor radar chain based on hough mode decomposition seasonal variations of different tides in the mesosphere and lower thermosphere are investigated from wind observations of a meteor radar chain on the basis of hough mode decomposition first the observed winds are decomposed into different diurnal semidiurnal and terdiurnal tidal components different seasonal patterns are revealed for each component pronounced semiannual oscillation sao is presented in the diurnal component while latitude dependent seasonal variation is found in the semidiurnal and terdiurnal components at the low midlatitude stations the semiannual annual oscillation is relatively stronger then hough mode decomposition is utilized to extract the dominant tidal modes of each decomposed component it is found that each component is dominated by one of its symmetric tidal modes with strong seasonal dependency apparent sao is observed in the dominant 1 1 mode 2 4 mode is strong in the autumn and winter months after the september equinox based on the extracted results we further map the three dimensional distribution latitude altitude season of each tidal component the mapped results are finally compared with the corresponding values observed by the thermosphere ionosphere mesosphere energetics and dynamics doppler interferometer tidi and modeled from the global scale wave model gswm each mapped tidal component agrees well with corresponding tidi observation in the seasonal variation meanwhile coincidences are found in the seasonal dependency of the diurnal component between the mapped values and the modeled results from gswm while difference between them exists in that of the semidiurnal one

late cretaceous magmatism in madagascar palaeomagnetic evidence for a stationary marion hotspot late cretaceous basaltic volcanics in the morondava basin sw madagascar possess high quality and pre fold palaeomagnetic data declination 353 5 inclination 54 8 95 2 4 the palaeomagnetic data are all of normal magnetic polarity and remanence acquisition is linked to the terminal stages of the cretaceous normal superchron 83 ma this is sustained by an 40ar 39ar age of 83 6 1 6 ma from one of the tested basaltic flows a precise u pb zircon baddeleyite age from northeast madagascar demonstrates magmatism at least back to 91 6 0 3 ma thus reliable isotope ages for the madagascar cretaceous igneous province span a range of 8 million years late cretaceous palaeomagnetic data obtained from volcanics and dolerites all over madagascar are directionally concordant and the combined palaeomagnetic pole latitude 68 5 n longitude 230 3 e a95 5 5 n 8 studies sampling age range ca 84 90 ma represents one of the best late cretaceous poles for the former gondwanan elements the collective palaeomagnetic data yield a palaeolatitude of 45 3 s 5 3 4 7 for the proposed focal point of the marion plume volcan de l androy southeast madagascar during the late cretaceous this is in perfect agreement with hotspot controlled reconstructions that place the marion hotspot 46 0 s beneath southeast madagascar during the late cretaceous setting true polar wander aside hotspot movements in the indian ocean do not appear to exceed ca 0 75 cm yr and the marion hotspot appears stationary within the resolution power of palaeomagnetic data

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

k ar geochronology of a middle miocene submarine volcano plutonic complex in southwest japan a volcano plutonic complex in the susa area southwest japan consists of the yamashima andesites the koyama gabbros and syn plutonic porphyrite dykes derived from a common basaltic andesite magma the complex is closely associated with middle miocene turbidite deposits the yamashima andesites are composed mainly of basaltic andesite feeder dykes massive submarine lavas with hyaloclastites and their reworked deposits the lavas and deposits immediately overlie turbidite deposits indicating submarine volcanic activity the koyama gabbros formed hornfels by contact metamorphism of the surrounding turbidites and andesites highly purified clinopyroxene and plagioclase mineral separates from the yamashima andesites were dated by a k ar method using an ultra low blank k analysis procedure ages obtained from duplicate analyses are 16 5 1 5 15 2 1 4 15 8 1 7 and 16 5 2 0 ma for clinopyroxene and 14 2 0 8 15 2 0 9 and 15 6 0 9 ma for plagioclase the clinopyroxene and plagioclase data define a mineral isochron age of 14 7 0 9 1 ma with an initial 40 ar 36 ar ratio of 297 3 2 4 1 suggesting that clinopyroxene has no excess argon and can be reliably dated by k ar most of the groundmass ages are considerably younger 12 1 14 6 than the isochron age perhaps due to argon loss during alteration the gabbros give ages of 14 2 0 3 and 14 1 0 3 ma for biotite and 13 7 0 3 and 13 7 0 7 ma for green hornblende the porphyrite dyke yields an age of 12 5 0 3 ma for the groundmass and the pelitic hornfels gives a biotite age of 14 8 0 3 ma our new k ar ages together with previous studies show that a series of geological events took place in the susa area between 16 and 13 ma conglomerates and sandstones were deposited in the beginning of marine transgression subsequent abrupt deepening led to deposition of a thick black shale unit turbidite deposits and large scale submarine channel fill deposits coeval igneous activity formed the volcano plutonic complex the magmato tectonic event was synchronous with the opening of the japan sea and the associated clockwise rotation of the southwest japan arc sliver recording a unique tectonic setting

nonmigrating diurnal tides in the thermosphere 1 horizontal wind measurements from the hrdi and windii instruments on the upper atmosphere research satellite are analyzed to reveal the most prominent nonmigrating diurnal tidal components at 95 km the eastward propagating diurnal tide with zonal wave number s 3 de3 the standing s 0 diurnal oscillation d0 and the westward propagating diurnal tide with s 2 dw2 the strongest de3 occurs primarily during northern hemisphere summer fall with maximum eastward winds near the equator of order 15 ms 1 and is a vertical extension of the s 3 kelvin wave the first antisymmetric mode of de3 dominates during october april with maximum meridional winds near the equator of order 8 ms 1 d0 exists during nearly all months and is nonsymmetric about the equator with maximum northward wind amplitudes in the southern hemisphere of order 7 10 ms 1 dw2 closely resembles the first symmetric propagating mode from classical tidal theory with maximum northward wind amplitudes of order 10 12 ms 1 during september through february the combination of de3 d0 and dw2 with dw1 gives rise to significant longitude variations in the diurnal tide between 40 latitude forcing in the global scale wave model gswm is calibrated according to the above observations thus enabling global estimates of nonmigrating tidal temperatures and other fields for instance it is estimated that the temperature and eastward wind perturbations associated with de3 may be as large as 20k and 35 ms 1 at 145 km and 115 km respectively over the equatorial region during july

interannual variability in the longitudinal structure of the low latitude ionosphere due to the el nino southern oscillation 1 the ratio of monthly median fof2 values between the ionosondes at maui 20 8 n 156 e geographic 21 2 n 90 4 e geomagnetic and yamagawa 31 2 n 130 6 e geographic 20 6 n 160 9 e geomagnetic from january 1960 to june 1993 are used to investigate interannual variability in the wave 4 longitudinal structure of the low latitude f region ionosphere analysis of global positioning system total electron content between january 1998 and december 2008 reveals that the ratio between these two locations is a suitable proxy for the amplitude of the wave 4 longitudinal structure in the northern hemisphere significant interannual variability is present in the fof2 ratio after removing the solar cycle and intra annual variability the remaining variability is thought to be due in part to changes in atmospheric and oceanic circulations arising from the el nino southern oscillation enso wavelet analysis reveals that similar periodicities and occurrence times exist for the fof2 ratio monthly anomalies and sea surface temperature anomalies represented by the oceanic nino index oni furthermore the yearly oni extreme value is well correlated with the extreme value of the fof2 ratio monthly anomalies in the subsequent 5 months this surprising connection is attributed to changes in tropospheric convection and hence latent heating associated with changing sea surface temperatures due to the enso changing distributions of latent heat tidal forcing are thought to induce changes in the strength of the upward and eastward propagating diurnal tide with zonal wave number s 3 de3 which subsequently produces the observed changes in the amplitude of the wave 4 longitudinal structure through modulation of the electric fields generated by the dynamo mechanism in the ionospheric e region our results demonstrate that there is significant interannual variability in the ionospheric wave 4 longitudinal structure and further indicate that the enso phenomenon represents a source of ionospheric variability which has previously not been considered

nightglow zenith emission rate variations in o 1 s at low latitudes from wind imaging interferometer windii observations volume emission rate data of the o 1 s nightglow layer measured by the wind imaging interferometer windii aboard the upper atmosphere research satellite uars are vertically integrated to give equivalent zenith column emission rates the data are restricted to tropical latitudes and categorized according to season the migrating tidal signature is extracted by plotting zonally averaged data as a function of local time the main features are a premidnight maximum at the equator during equinox intervals and a midnight maximum at 20 n and s the two equinoxes are not equivalent nor is the behavior identical in the two hemispheres winter periods show little or no well defined tidal signature longitudinal variations at fixed local time were also studied these variations are larger than the tidal signature and are geographically random showing no consistent identification with land masses some of these variations could be of planetary scale while others are probably long wavelength gravity waves but in any case they were seen to extend over 10 of latitude at least zenithal emission rate measurements exceeding 500 r occurred at the coincidence of these longitudinal wave structures and the tidal maxima the suggestion is put forward that much of the perceived tidal variability in the tropical lower thermosphere may be explained by such wave tide superpositions

1980 volcanic eruption reported on marion island abstract the first volcanic eruption in the recorded history of marion island 46 54 s 37 45 e occurred between february and october 1980 at a locality on the west coast it was a minor event that passed unnoticed at the meteorological station 20 km distant the discovery was made on november 4 by five expedition members who walked around the island when examined in more detail on november 25 the lava was still warm in places and numerous fumaroles existed three blocky flows emanated from two adjacent cinder cones built up on a pre existing phreatomagmatic tuff cone known as kaalkoppie the largest flow covers an area of about seven hectares and a further two hectares have been inundated by ash another flow poured seawards to form a new beach front blocking access to what was previously the largest elephant seal wallowing ground on the island no earth tremors were felt and the activity seems to have ended for the time being

nonmigrating diurnal tides in the equatorial middle atmosphere abstract data from the nimbus 7 limb infrared monitor of the stratosphere lims are used to extend the analysis of diurnal tides in the middle atmosphere to include the zonally symmetric and eastward propagating components these modes show vertical and meridional structures that are generally consistent with the predictions of linear tidal theory the zonal and meridional wind fields are calculated from the tidal temperatures diurnal perturbations in lims temperature and derived winds agree well with equinoctial model calculations comparisons with day night differences of radiosonde temperature and rocket winds show qualitative agreement in vertical structure and amplitude the zonally symmetric and eastward migrating tidal components show a higher degree of temporal variability than the sun synchronous component these modes at times contribute substantially to the diurnal signal in wind and temperature with combined amplitudes equal to or in excess of the amplitude of the main migrating diurnal tid