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

spectral mixture modeling a new analysis of rock and soil types at the viking lander 1 site a viking lander 1 image was modeled as mixtures of reflectance spectra of palagonite dust gray andesitelike rock and a coarse rocklike soil the rocks are covered to varying degrees by dust but otherwise appear unweathered rocklike soil occurs as lag deposits in deflation zones around stones and on top of a drift and as a layer in a trench dug by the lander this soil probably is derived from the rocks by wind abrasion and or spallation dust is the major component of the soil and covers most of the surface the dust is unrelated spectrally to the rock but is equivalent to the global scale dust observed telescopically a new method was developed to model a multispectral image as mixtures of end member spectra and to compare image spectra directly with laboratory reference spectra the method for the first time uses shade and secondary illumination effects as spectral end members thus the effects of topography and illumination on all scales can be isolated or removed the image was calibrated absolutely from the laboratory spectra in close agreement with direct calibrations the method has broad applications to interpreting multispectral images including satellite images

solar semidiurnal tide in the dusty atmosphere of mars abstract vertical coupling due to the solar semidiurnal tide in mars s atmosphere and effects on zonal mean temperature and wind structures are investigated using a numerical model the model provides self consistent solutions to the coupled zonal mean and tidal equations from the surface to 250 km breaking convective instability of the semidiurnal tide is parameterized using a linear saturation scheme with associated eddy diffusivities thermal forcing in the model gives rise to surface pressure perturbations and middle atmosphere zonal mean winds and temperatures that are consistent with available measurements and general circulation models results presented here primarily focus on globally elevated dust levels during southern hemisphere summer conditions similar to those experienced by the viking 1 and viking 2 landers during the 1977 global dust storms semidiurnal temperature and wind amplitudes maximize in the winter hemisphere and exceed 50 k and 100 m s 1 above 150 km and are typically 10 2

a climatology of tides in the antarctic mesosphere and lower thermosphere 1 a function that approximates atmospheric tidal behavior in the polar regions is described this function is fitted to multistation radar measurements of wind in the mesosphere and lower thermosphere with the aim of obtaining a latitude longitude height description of the variation of tides over the whole antarctic continent archival wind data sets are combined with present day ones to fill the spatial distribution of the observations and to reduce the potential effects of spatial aliasing multiple years are combined through the compilation of monthly station composite days yielding results for each month of the year despite potential problems associated with year to year variations in the tidal phase a useful climatology of antarctic zonal and meridional tidal wind components is compiled the results of the fits reproduce the major features of the high latitude tidal wind field the dominance of the semidiurnal migrating mode in the winter months and the presence of a semidiurnal zonal wave number one component in the summer months it is also found that the summer semidiurnal tide contains a zonal wave number zero component

structure of the nonmigrating semidiurnal tide above antarctica observed from the timed doppler interferometer 1 spatial structure and temporal evolution of the nonmigrating semidiurnal tidal components over antarctica are determined by analyzing horizontal wind measurements in the mesosphere and lower thermosphere mlt collected using timed doppler interferometer tidi on the nasa thermosphere ionosphere mesosphere energetics and dynamics timed satellite from 2002 to 2007 the data were organized into six specific intervals of approximately 60 days corresponding to the timed yaw periods the results confirm the existence of a westward propagating zonal wave number 1 w1 semidiurnal tidal component in the antarctic mlt meridional wind field prior to the austral summer solstice this wave achieves a peak amplitude near 20 m s 1 at 90 km and is vertically stratified while extending latitudinally from the pole to 60 s a similar structure is observed in the zonal wind field however the amplitude maximizes around the austral summer solstice during the yaw period spanning 15 november to 15 january in addition to a strong latitudinal gradient in amplitude the w1 component also shows a vertical wavelength from 20 km near the pole to 40 km at 60 s the amplitude and phase agree well with ground based meteor radar observations from the south pole evidence for significant though weaker standing s0 and w3 components is also found these components diminish in the vicinity of the pole and appear during the winter months with latitudinally restricted structures the vertical wavelength of the s0 component during the summer is 25 km similar to the w1 component during the winter the wavelength of the s0 component becomes nearly evanescent

topographic connections with density waves in mars aerobraking regime 1 atmospheric densities derived from measured acceleration of several mars orbiters reveal large amplitude sun synchronous longitudinal density variations at altitudes of about 100 160 km these variations are associated with vertically propagating nonmigrating solar thermal tides that are excited near mars surface and propagate into the thermosphere excitation of these waves is associated with the zonally asymmetric component of the near surface heating distribution and is commonly attributed to topographic modulation of solar heating however there are other possible contributors to the excitation of nonmigrating tides including zonal variations in surface properties and wave wave nonlinear interactions whose relative contributions remain unexplored in this study we use a general circulation model in combination with the mars global surveyor accelerometer measurements to isolate the different waves responsible for the observed density structures while it is evident that topography accounts for most of the waves amplitudes the surface thermal inertia and albedo are found to have a nonnegligible contribution to the eastward propagating diurnal tide with zonal wave number s 1 and the standing s 0 diurnal tide previous studies have reported the dominance of wave numbers 2 and 3 in the resulting sun synchronous aerobraking density maps we show that wave number 1 has a comparable amplitude and is mostly the result of mapping the diurnal standing wave into a near sun synchronous orbit while most of the nonmigrating tides at thermospheric altitudes are generated by an interaction between the migrating solar radiation and the dominant topography harmonics we also find that wave wave interaction is necessary to explain some of the observed density features

a model for formation of dust soil and rock coatings on mars physical and chemical processes on the martian surface 1 a model is presented here to explain the generation of surface material on mars using chemical magnetic and spectroscopic data from mars and geologic analogs from terrestrial sites one basic premise is that the dust soil units are not derived exclusively from local rocks but are rather a product of global and possibly remote weathering processes another assumption in this model is that there are both physical and chemical interactions of the atmosphere with dust particles and that these two processes create distinctly different products physical processes distribute dust particles on rocks and drift units forming physically aggregated layers these are reversible processes chemical reactions of the dust soil particles create alteration rinds on rock surfaces and cohesive crusted surface units between rocks both of which are relatively permanent materials according to this model the dominant components of the dust soil particles are derived from alteration of volcanic ash and tephra and contain primarily nanophase and poorly crystalline ferric oxide oxyhydroxide phases as well as silicates these phases are the alteration products that formed in a low moisture environment these dust soil particles also contain a smaller amount of material that was exposed to more water and contains crystalline ferric oxides oxyhydroxides sulfates and clay silicates these components could have formed through hydrothermal alteration at steam vents or fumeroles thermal fluids or through evaporite deposits wet dry cycling experiments are presented here on mars soil analogue mixtures containing poorly crystalline and crystalline components dominated by nanophase to 2 m diameter particles cemented products of these soil mixtures are formed in these experiments and variation in the surface texture was observed for samples containing smectites nonhydrated silicates or sulfates reflectance spectra were measured of the initial particulate mixtures the cemented products and ground versions of the cemented material the spectral contrast in the visible near infrared and midinfrared regions is significantly reduced for the cemented material compared to the initial soil and somewhat reduced for the ground cemented soil compared to the initial soil the results of this study suggest that transient fluvial activity on mars will have a profound effect on the texture and spectral properties of the dust soil particles on the surface the model developed in this study provides an explanation for the generation of cemented or crusted soil units and rock coatings on mars and may explain albedo variations on the surface observed near large rocks or crater rims

climatological features of mesosphere and lower thermosphere stationary planetary waves within 40 latitude 1 zonal and meridional wind measurements from the high resolution doppler imager hrdi and wind imaging interferometer windii instruments on the upper atmosphere research satellite uars are used to construct monthly average stationary planetary wave spw structures from 15 km to 110 km over the period december 1991 to september 1994 because of viewing constraints of the instruments intercomparisons between northern hemisphere nh and southern hemisphere sh structures and seasonal evolutions are mainly confined to 40 latitude the largest zonal wave number s 1 amplitudes 10 25 m s 1 in the stratosphere and mesosphere at 40 exist in the zonal wind fields and occur during september january in the nh and july october in the sh spw s 2 structures are much less prevalent especially above 80 km because of more restrictive filtering effects due to the mean winds above about 70 km s 1 wave amplitudes 5 10 m s 1 are more uniform extending over all nonsummer months in both hemispheres up to 80 90 km with similar amplitudes existing throughout the year at higher altitudes our interpretation is that the spw above about 80 90 km during summer owe their existence to ducting from the winter hemisphere in agreement with numerical simulations by pogoreltsev and sukhanova 1993 the origin of spw above about 80 km during winter at midlatitudes is not possible to determine unambiguously phase structures undergo a transition from vertical propagation with long vertical wavelengths hundreds of kilometers below 80 km to either evanescent behavior or an extreme shortening of vertical scale at higher altitudes this change in phase behavior may be connected with negative values in refractive index q for quasi geostrophic wave propagation which occur over a narrow height region near 80 km during almost every month this interruption of normal phase progression makes it impossible to distinguish the origin of the planetary wave oscillations from 1 those that tunnel through the q 0 region and 2 those that might be excited in situ by zonally asymmetric momentum deposition from gravity waves which have undergone filtering by the stratospheric planetary wave wind field in addition quantitative estimates of aliasing due to the diurnal tide indicate that it may be of sufficient magnitude to contaminate retrieved spw structures between 80 90 km and 100 110 km where local time coverages are incomplete comparisons are made between the observed spw structure and those from the horizontal wind model hedin et al 1993 1996 this model is found to provide a reasonable approximation to nh winter spw s 1 structures below 80 km but severely underestimates the amplitudes of spw in the sh

application of manley rowe relation in analyzing nonlinear interactions between planetary waves and the solar semidiurnal tide during 2009 sudden stratospheric warming event

tidal variability in the ionospheric dynamo region 1 the seasonal and interannual variability of migrating sun synchronous and nonmigrating solar atmospheric tides at altitudes between 100 and 116 km are investigated using temperature measurements made with the saber instrument on the timed spacecraft during 2002 2006 quasi biennial variations of order 10 15 in migrating diurnal and semidiurnal tidal amplitudes are found presumably due to modulation by the quasi biennial oscillation qbo as the tides propagate from their troposphere and stratospheric sources to the lower thermosphere a number of nonmigrating tidal components are found that have the potential to produce significant longitudinal variability of the total tidal fields the most prominent of these i e those that appear at amplitudes of order 5 10 k in a 5 year mean climatology include the zonally symmetric s 0 diurnal tide d0 the eastward propagating diurnal and semidiurnal tides with zonal wave numbers s 2 de2 and se2 and s 3 de3 and se3 and the following westward propagating waves diurnal s 2 dw2 semidiurnal s 1 sw1 s 3 sw3 and s 4 sw4 and terdiurnal s 5 tw5 these waves can be plausibly accounted for by nonlinear interaction between migrating tidal components and stationary planetary waves with s 1 or s 2 or by longitudinal variations of tropospheric thermal forcing additional waves that occur during some years or undergo phase cancellation within construction of a 5 year climatology include dw5 se1 se4 sw6 te1 tw1 and tw7 it is anticipated that the winds that accompany all of these waves in the 100 170 km region will impose longitudinal variability in the electric fields produced through the ionospheric dynamo mechanism thereby modulating vertical motion of the equatorial ionosphere and the concomitant plasma densities in addition to the wave 4 modulation of the equatorial ionosphere that has recently been discovered and replicated in modeling studies the waves revealed here will generate wave 1 sw1 sw3 d0 dw2 wave 2 sw4 tw1 wave 3 de2 se1 wave 4 de3 se2 dw5 sw6 te1 tw7 wave 5 se3 and wave 6 se4 components of this ionospheric variability depending on year and time of year however the absolute and relative efficiencies with which these waves produce electric fields remains to be determined

controls on palagonitization versus pedogenic weathering of basaltic tephra evidence from the consolidation and geochemistry of the keanakako i ash member kilauea volcano 1 on the summit of kilauea volcano incipient palagonitization and consolidation of vitric tephras from the 90 of the carbon is mantle derived we hypothesize that the palagonitized zones may denote the location of fossil steam vents similar to active vents exposed along circumferential faults on both the north and the south sides of the kilauea caldera elsewhere keanakako i tephras are weathering into pedogenic products that closely reflect modern environmental conditions under acidic soil conditions ph 6 0 tephra is undergoing dissolution with the development of opaline crusts on outcrop faces under more neutral soil ph 6 5 7 8 the pedogenic products reflect the degree of desilication of tephra mitigated by leaching dominantly smectite where mean annual rainfall is 50 cm yr and dominantly kaolinite allophane and or imogolite where rainfall exceeds 250 cm yr

prediction of some weathering trends of plutonic and volcanic rocks based on thermodynamic and kinetic considerations abstract the exposed crust consists mainly of plagioclase 35 quartz 20 k feldspar 11 volcanic glass 12 biotite 8 and muscovite 5 quartz is a resistate thus feldspars and glass represent approximately 75 percent of the labile minerals the weathering characteristics of these constituents are summarized in the context of thermodynamic mass balance and kinetic considerations experimentally determined release rate constants were used to predict the proportions of ca na and k released by feldspars of plutonic rocks granites to gabbros to weathering solutions the chemical weathering trends of the weathered residues calculated from the kinetic data conform closely to the initial trends observed in some recent weathering profiles demonstrating the accuracy of the predictions since the weathering of feldspars is controlled by processes that should not change through geological time the relative release rates of ca na and k from the feldspars of granitic rocks can be calculated for future and past episodes of continental weathering experimentally determined release rate constants are not available for a wide range of volcanic glass compositions but the limited data indicate that compositional trends are predictable in weathering profiles developed on volcanic rocks the kinetic data available for rhyolitic glasses accurately predict the initial weathering trends observed in a recent rhyolite weathering profile

mean zonal acceleration and heating of the 70 to 100 km region the dynamical interactions which occur in the atmospheric region around the mesopause 90 km determine the boundary characteristics for the thermospheric region above a significant data base of radar wind measurements exists which characterizes the global circulation at altitudes between 70 and 110 km in the present work using an empirical model of eulerian mean meridional motions based on monthly climatological winds from these radar data the net vertical motions in this atmospheric regime are derived from the continuity equation assuming empirical prescriptions of the mean density and temperature fields mean heat flux divergences and momentum flux divergences are estimated which exhibit very specific characteristics in the height versus latitude domain for winter summer and equinox conditions in both hemispheres a numerical circulation model including gravity wave mean flow and tide mean flow interactions is utilized to examine possible origins of these heat and acceleration sources at low latitudes 30 it is evident that atmospheric tides represent the primary wave source contribution to zonal mean acceleration and heating of this region of the atmosphere similarly at middle and high latitudes 30 below about 90 km dissipation of vertically propagating gravity waves appears to provide the dominant momentum source for the mean zonal circulation however above approximately 90 km and between about 40 and 70 latitude very significant regions of mean heating and acceleration exist which are not accounted for by the effects of vertically propagating gravity waves and tides the possible origins of these effects are examined we suggest that the two most likely candidates to explain these observed features are 1 obliquely propagating gravity waves and or 2 planetary scale waves

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

comparative study of short term diurnal tidal variability examination of the simultaneous temperature measurement from the sounding of the atmosphere using broadband emission radiometry saber instrument on board the thermosphere ionosphere mesosphere energetics and dynamics timed satellite not only confirms the existence of the inversion layer but also reveals the global nature of the inversion suggesting the presence of a transient planetary wave in the mesosphere the large tidal variability therefore is probably a consequence of the interaction between the transient planetary wave and tides this possibility is investigated by using the ncar thermosphere ionosphere mesosphere electrodynamics general circulation model time gcm and by comparing model results with the lidar saber and timed doppler interferometer tidi measurements with a large transient planetary wave specified at the model lower boundary the model is able to produce strong diurnal tidal variability comparable to that from the lidar observation and the modeled temperature inversion is similar to that from the saber measurement the model results suggest that the planetary tidal wave interaction excites nonmigrating tides and modulates the gravity modes and or the rotational modes of the diurnal migrating tide among the nonmigrating tides the diurnal zonally symmetric s 0 component is the strongest and its interaction with the planetary wave leads to a strong diurnal eastward wave number 1 component

a link between variability of the semidiurnal tide and planetary waves in the opposite hemisphere 1 horizontal wind observations over four years from the meteor radar at esrange 68 n 21 e are analyzed to determine the variability of the semidiurnal tide simultaneous global observations of temperature and geopotential from the saber satellite instrument are used to construct time series of planetary wave amplitudes and geostrophic mean zonal wind during northern hemisphere summer and fall the temporal variability of the semidiurnal tide at esrange is found to be well correlated with the amplitude of planetary wavenumber 1 in the stratosphere in high southern latitudes i e in the opposite hemisphere the correlations indicate that a significant part of the tidal variation at esrange is due to dynamical interactions in the southern hemisphere a corresponding robust correlation pattern for the esrange tides is not apparent at other times of the multiple years analyzed

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

global structure of the lunar tide in ionospheric total electron content 1 the global structure of the lunar tide in the ionosphere is studied based on observations of the global positioning system gps total electron content tec the unprecedented spatial and temporal resolution afforded by the gps tec observations enables illustration of the latitude longitude solar local time and seasonal variability of the lunar tide in the ionosphere based on analysis of the multi year mean from 1999 2008 the dominant component is generally the semidiurnal lunar tide however a significant diurnal variation is also observed in some instances the semidiurnal component achieves a maximum amplitude of 6 in the equatorial ionization anomaly crest regions and a slight hemispheric asymmetry is present with larger amplitudes in the northern hemisphere furthermore the maximum amplitudes in the semidiurnal lunar tide are found to occur during northern hemisphere winter and during 9 15 solar local time during certain years a secondary maxima in solar local time is also observed demonstrating the influence of the lunar tide on the prereversal enhancement lastly the observations reveal significant longitudinal variability in the semidiurnal lunar tide that is most prominent between november and february the presence of a longitudinal variation reveals the existence of nonmigrating components in addition to the dominant migrating semidiurnal lunar tide

the character of polar tidal signatures in the extended canadian middle atmosphere model the characteristics of the diurnal semidiurnal and terdiurnal tides zonal wave numbers 5 to 5 in temperature and zonal wind in the polar mesosphere and lower thermosphere region as simulated by the extended canadian middle atmosphere model are examined the most significant diurnal semidiurnal and terdiurnal tides in the polar regions are ds0 dw1 and de1 sw3 sw2 sw1 ss0 se1 and se2 and tw3 ts0 and tw1 respectively and their latitudinal structures seasonal variations and hemispheric asymmetries noted of these components ds0 tw1 ts0 and tw3 exhibit a seasonally symmetric variation with both hemispheres strengthening simultaneously on the other hand dw1 strengthens asymmetrically so that when one hemisphere is strong the other is weak the remainder show no seasonal tendency but vacillate on shorter than seasonal time scales in a symmetric or antisymmetric manner at different times of the year global scale correlations of the amplitudes of the migrating tides dw1 sw2 and the stationary planetary wave 1 and the assumed child nonmigrating tides are also examined the results indicate that the correlations are highly time scale dependent and the significant correlations seen with the original time series are mainly due to longer term variations 18 days there are no consistent global correlations associated with the short term variations 18 days among these waves

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

evidence for stratosphere sudden warming ionosphere coupling due to vertically propagating tides 1 observations of the global positioning system gps total electron content tec are used to study the coupling between the 2009 sudden stratospheric warming ssw and ionospheric perturbations the observations reveal both migrating and nonmigrating perturbations to the semidiurnal tide in the equatorial ionization anomaly crest region that are associated with changes in electric fields induced by the tidal dynamo in particular a significant enhancement is observed in the nonmigrating semidiurnal westward propagating tide with zonal wavenumber 1 sw1 in gps tec during the ssw the sw1 perturbations in the low latitude ionosphere are found to oscillate with a similar period as planetary wave 1 activity in the northern hemisphere stratosphere this connection is attributed to the nonlinear interaction between tides and planetary waves and strongly supports the theory that planetary wave tide interaction is the primary mechanism coupling ssws to ionospheric variability enhancements are also observed in the nonmigrating semidiurnal tide with zonal wavenumber 0 s0 during this time period and may be related to the nonlinear interaction between the migrating semidiurnal tide and planetary wave 2 the connection between planetary wave 2 and s0 is however less clear which may be attributed to differences in the zonal mean zonal winds in the mesosphere and lower thermosphere during the times of peak planetary wave 1 and planetary wave 2 activity we conclude that the changing zonal winds during ssws play an important role in the coupling between ionospheric variability and the forcing from planetary waves of lower atmospheric origin during ssws

estimation of the equivalent rayleigh friction in mesosphere lower thermosphere region from the migrating diurnal tides observed by timed 1 we use thermosphere ionosphere mesosphere energetics and dynamics timed global temperature and wind data from 2002 to 2007 to investigate the damping of the diurnal tide horizontal winds are measured by tidi and are calculated from saber temperature measurements the determination of tidal winds from saber temperature depends on the damping and therefore the discrepancy between tidi and saber determinations of the wind tides can be used to calculate the tidal damping this damping is approximated here by an equivalent rayleigh friction erf and it is adjusted to minimize the difference in winds derived from saber and tidi data the results show that during some periods the erf coefficient can be very large over narrow vertical regions of about 5 km 10 5 s 1 in low latitudes and about 10 4 s 1 in midlatitudes the magnitude and shape of the vertical profiles change with latitude and season the peak in the vertical profile of erf is larger and located at a higher altitude in summer than in winter and the erf coefficients at 40 are stronger than at 20 in both hemispheres the erf deduced in this study without a priori assumption about the mechanism of the damping shows a seasonal variation that is clearly consistent with the seasonal variation of the zonal mean wind the maximum erf generally coincides with the altitudes of strongest wind reversal in the mesopause region

regional dust deposits on mars physical properties age and history major dust storms on mars play an important role in the deposition and removal of fine dust material thermal radar and visual remote sensing observations provide important constraints on the martian regolith which have been used to determine the location and physical properties of regional dust deposits these deposits are located in three northern equatorial regions tharsis 20 s to 50 n 60 to 190 w arabia 5 s to 30 n 300 to 360 w and elysium 10 to 30 n 210 to 225 w they are covered by fine 2 40 m bright albedo 0 27 particles with fewer exposed rocks and coarse deposits than found elsewhere dust is currently deposited uniformly throughout the equatorial region at a rate of 40 m global storm over geologic time the rate of accumulation may vary from 0 to 250 m yr due to changes in atmospheric conditions produced by orbital variations dust deposited during global storms is subsequently removed only from dark regions resulting in a net accumulation in the low inertia bright regions the thickness of these current dust deposits is 0 1 2 m the thermal inertia places a lower limit of 0 1 m on the thickness of these deposits while the sparse but ubiquitous presence of exposed rocks and the degree of visible mantling indicate that the thickness is less than 5 m dual polarization radar observations of a very rough texture in tharsis are consistent with this model with a 2 m thick dust layer burying most of the surface rocks but permitting radar sampling of the rough subsurface based on their thickness and rate of accumulation the age of these deposits is 105 106 years suggesting a cyclic process of deposition and removal one possible cause may be cyclic variations in the magnitude and location of maximum wind velocities related to variations in mars orbit at present perihelion and maximum wind velocities occur in the south whereas regional dust deposits occur in the north suggesting net transport from south to north orbital parameters oscillate with periods ranging from 5 104 to 106 years the agreement between these periods and the dust deposit age suggests a possible link at different stages in orbit evolution maximum wind velocities will occur in the north with subsequent erosion and redistribution of the accumulated fines based on this model much of the uppermost martian surface is very young and is being continually reworked

short term variability in the migrating diurnal tide caused by interactions with the quasi 2 day wave 1 the migrating diurnal tide is one of the dominant dynamical features in the low latitudes of the earth s mesosphere and lower thermosphere mlt region representing the atmospheric response to the largest component of solar forcing ground based observations of the tide have resolved short term variations attributed to nonlinear interactions between the tide and planetary waves that are also in the region using the ncar thermosphere ionosphere mesosphere electrodynamics general circulation model time gcm we simulate a quasi 2 day wave qtdw event under late january conditions in this case sideband sum and difference child waves are resolved indicating that a nonlinear interaction is occurring between the qtdw and the tide the migrating diurnal tide in the mlt displays local amplitude decreases of 20 40 as well as a shortening of vertical wavelength by roughly 4 km examining the physical mechanisms driving the interaction nonlinear advection is found to result in amplification of the tide in some regions and damping in others manifesting as increased smoothing of the tidal structure when the qtdw is present in the mlt additionally the qtdw also enhances the easterly summer mean wind jet that can also account for changes in tidal amplitude and vertical wavelength we find that qtdw induced background atmosphere changes in time gcm can drive tidal variability at levels greater than nonlinear advection a possibility not previously considered

troposphere thermosphere tidal coupling as measured by the saber instrument on timed during july september 2002 1 coupling between the troposphere and lower thermosphere due to upward propagating tides is investigated using temperatures measured from the saber instrument on the timed satellite the data analyzed here are confined to 20 120 km altitude and 40 latitude during 20 july to 20 september 2002 apart from the migrating sun synchronous tidal components the predominant feature seen from the satellite frame during this period is a wave 4 structure in longitude with extrema of up to 40 50 k at 110 km amplitudes and longitudes of maxima of this structure evolve as the satellite precesses in local time and as the wave s responsible for this structure vary with time the primary wave responsible for the wave 4 pattern is the eastward propagating diurnal tide with zonal wave number s 3 de3 its average amplitude distribution over the interval is quasi symmetric about the equator similar to that of a kelvin wave with maximum of about 20 k at 5 s and 110 km de3 is primarily excited by latent heating due to deep tropical convection in the troposphere it is demonstrated that existence of de3 is intimately connected with the predominant wave 4 longitude distribution of topography and land sea difference at low latitudes and an analogy is drawn with the strong presence of de1 in mars atmosphere the predominant wave 2 topography on mars and the wave 2 patterns that dominate density measurements from the mars global surveyor mgs spacecraft near 130 km additional diurnal semidiurnal and terdiurnal nonmigrating tides are also revealed in the present study these tidal components are most likely excited by nonlinear interactions between their migrating counterparts and the stationary planetary wave with s 1 known to exist in the southern hemisphere during this period just prior to the austral midwinter stratospheric warming of 2002

tidal analysis of meridional winds at the south pole using a vhf interferometric meteor radar 1 atmospheric tides are perturbations driven by the periodic absorption of solar radiation they manifest themselves everywhere in the atmosphere and an understanding of their sources propagation and interaction with other waves is vital to comprehend the global atmosphere in order to measure the horizontal wind field in the mesosphere lower thermosphere mlt over the geographical south pole and use these measurements to understand the large scale dynamics of this region a vhf meteor radar was installed at the amundsen scott station at the south pole in 2001 the radar operated for a few months in 2001 and with minor interruptions in 2002 and 2003 however toward the end of 2003 receiver problems caused a drop in our meteor echo rates preventing us from getting tidal results after october 2003 we report on the temporal behavior of the diurnal and semidiurnal tides observed in the meridional wind field at mesospheric and lower thermospheric heights in the vicinity of the geographic south pole with the interferometric capabilities of this radar we also document for the first time the vertical structure of these tides the zonal wave number one component of the diurnal tide shows consistency for all years that we analyze on the other hand the zonal wave number one component of the semidiurnal tide shows significantly more year to year variability our results are compared to previous observations and model predictions a significant decrease in the amplitude of this oscillation from december 2002 to february 2003 is also observed and discussed

seasonal variation of martian middle atmosphere tides observed by the mars climate sounder the increased local time coverage retrieved from the mars climate sounder on board the mars reconnaissance orbiter enables the direct extraction of thermal tides in the mars middle atmosphere using temperature profiles from mars years 30 to 32 we studied the latitudinal and seasonal variations in the tides and stationary planetary waves with zonal wave numbers s 1 3 the amplitude of the migrating diurnal tide exhibits strong semiannual variations in both the equatorial region and the middle latitudes of southern hemisphere the migrating semidiurnal tide sw2 shows clear semiannual variations in the equatorial region and the middle latitudes of northern hemisphere but an annual variation in the southern hemisphere the spatial and temporal correlations between the sw2 amplitude and the density scaled opacity of both the water ice and dust in the equatorial region may provide a possible explanation for the tidal forcing of sw2 three kelvin modes with zonal wave numbers 1 3 de1 de3 have significant seasonal variations in the equatorial region de1 appears to have a semiannual variation whereas de2 and de3 have clear annual variations herein for the first time we have extracted the westward propagating diurnal tide with s 2 and 3 and semidiurnal tide with s 1 in the mars middle atmosphere using observational data all three waves have asymmetric latitudinal distributions which should correspond to their possible excitation source i e nonlinear interactions between stationary planetary waves and migrating tides

zonally symmetric oscillations in the northern hemisphere stratosphere during the winter of 2003 2004 1 the paper presents clear evidence of zonally symmetric planetary waves with very large amplitudes present in the uk met office zonal wind data of the northern hemisphere stratosphere in the winter of 2003 2004 the spectral analysis reveals that three prevailing periods of 23 17 and 11 days contribute to the observed zonally symmetric oscillations these waves are extracted from the data and their amplitudes and phases are studied in detail depending on height and latitude the wave amplitudes particularly those of the 11 and the 17 day zonally symmetric waves clearly indicate the presence of two latitudinal branches of amplifications centred at 50 60 n and 20 30 n the phase analysis shows that these waves are vertically upward propagating waves and that the waves from the high latitude and tropical branches are almost out of phase a possible forcing mechanism is suggested the zonally symmetric waves play an important role in coupling the dynamical regimes of the high and low latitude stratosphere particularly during the major stratwarm event in the arctic winter of 2003 2004

geographical distribution of long term changes in the height of the maximum electron density of the f region a nonmigrating tide effect 1 the geographical distribution of trends in the height of the maximum electron density of the f2 region hmf2 seemed to indicate that ionospheric stations showing decreasing i e negative hmf2 trends are mostly located on or in the vicinity of seashores in contrast ionospheric stations in continental areas exhibit generally increasing i e positive hmf2 trends on the basis of the present study it is shown that considering the whole world the geographical distribution of hmf2 trends is affected essentially by the nonmigrating tidal wind moreover besides the field aligned drift the elecrodynamical drift must also be considered in the development of hmf2 trends taking into account both the field aligned and the electrodynamical drift northward eastward tidal winds and southward westward tidal winds would create downward and upward drifts respectively in the northern hemisphere but southward eastward and northward westward tidal winds in the southern hemisphere an upward drift is accompanied by an increase and a downward drift is accompanied by a decrease of hmf2 it has been suggested that because of the thermal driven origin of the nonmigrating tides the distribution may also be connected with ocean currents warming or cooling the neighborhood of the coastline the effect of ocean currents would create downward drift due to cooling at the western coastlines of the continents but upward drift at the eastern coastlines as a result of the warming this has been shown by comparing the distribution of hmf2 trends with the map of ocean currents the corresponding hmf2 trends may develop because of changes in the land sea warming ratio where the land surface air temperature increases faster than the sea surface air temperature

seasonal and latitudinal variations of the electron density nonmigrating tidal spectrum in the topside ionospheric f region as resolved from champ observations in this study we present for the first time the nonmigrating tidal spectrum for the electron density in the topside ionosphere on global scale for different seasons at both solar maximum and minimum conditions the electron density observations from the champ challenging minisatellite payload satellite provide evidence for prominent nonmigrating tides at different latitude regions at middle and high latitudes the most prominent diurnal tides are de1 d0 and dw2 as well as semidiurnal tides sw1 and sw3 preferably during equinox seasons de1 is only found in the northern middle and high latitudes while d0 and dw2 are much stronger in the southern hemisphere these tides are believed to be driven by the thermospheric winds through ion neutral interactions at equatorial and low latitude regions the most prominent diurnal tides are de2 and de3 de2 is found to be present at low latitude regions throughout the whole year with larger amplitudes in the southern hemisphere while de3 shows largest amplitudes symmetric above the dip equator at the equatorial ionization anomaly eia crest region during september equinox a general antiphase behavior between the eia crest and trough is observed for the tides de3 de2 dw2 and sw3 we consider this as strong evidence for the modulation of the eia electron density by the e layer zonal electric field via the ion fountain effect an exception is the tidal component d0 which exhibits antiphase variations between the two hemispheres the phase value at the equatorial trough is halfway between those of the two hemispheres presently we cannot give an explanation for it and study concerning special model effort is further needed

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

winter temperature tides from 30 to 110 km at mcmurdo 77 8 s 166 7 e antarctica lidar observations and comparisons with wam we provide the first characterization of diurnal and semidiurnal thermal tides in temperature from 30 to 110 km in the winter season may through august at mcmurdo 77 8 s 166 7 e antarctica the observations were made with an fe boltzmann temperature lidar in 2011 and 2012 over 330 h of winter data are compiled into a composite day of temperature perturbations that significantly reduce the incoherent wave effects while preserving the coherent tidal signatures both diurnal and semidiurnal tides have small amplitudes less than 3 k below 100 km with vertical wavelengths of 29 and 23 km respectively a new finding of this study is the fast growth of diurnal and semidiurnal tidal amplitudes above 100 km to at least 15 k near 110 km exceeding that of the freely propagating tides originating from the lower atmosphere such fast growth exists for all kp index cases and diurnal amplitude increases to 15 30 k at 110 km with larger kp indices corresponding to larger tidal amplitudes and faster growth rates the slopes of diurnal tidal phases become steeper above 100 km and the tidal phases barely change with altitude from 100 to 106 km the tidal growth behavior is reproduced in the whole atmosphere model wam with phases comparable to the observations but magnitudes significantly underestimated wam compares reasonably well with the observations below 100 km the observed significant amplitude increases and phase structure changes suggest additional tidal sources near or above 100 km which deserve future investigation

monthly tidal temperatures 20 120 km from timed saber 1 the saber instrument on the timed satellite provides unprecedented geographical coverage for the determination and study of atmospheric tides however the slow local time precession rate of timed can cause longer term temperature variations to alias into the tidal signals a new method of analyzing satellite data for tides has been developed to circumvent this difficulty but at the expense of temporal resolution of the tidal fields i e 120 day mean tidal structures are obtained in this work we apply this method to saber temperature data to derive a series of 120 day mean tidal structures extending between 20 and 120 km altitude 50 s 50 n latitude and centered on each month from september 2003 to september 2004 in addition to the migrating sun synchronous diurnal and semidiurnal tides a number of nonmigrating tides are revealed in the saber measurements some of these waves are thought to originate via nonlinear coupling between the migrating tides and the stationary planetary wave with zonal wave number s 1 other nonmigrating tidal components appear to be forced by latent heating due to deep tropical convection of the latter the eastward propagating diurnal tide with s 3 is dominant and is as large as the migrating diurnal tide during some months of particular interest is the wave 4 structure with respect to longitude that characterizes both the diurnal and semidiurnal total tidal fields this feature is a result of the predominant wave 4 topography land sea longitude dependence at the surface which is reflected in the diurnal and semidiurnal components of the latent heating rates due to deep tropical convection the ability of the global scale wave model gswm to approximate the observed tidal fields including the wave 4 total tidal structures is also assessed

source regions for antarctic mlt non migrating semidiurnal tides 1 source regions for the westward propagating zonal wavenumber one and three components of the semidiurnal tide observed in the summer mesosphere and lower thermosphere over antarctica are identified by correlating local tidal variations with global planetary wave one activity in the stratosphere and lower mesosphere the advantages of using zonal wavenumber resolved tidal amplitudes for such a study are described the results support the prediction of a source region in the northern hemisphere

long term oscillations of the wind field in the tropical mesosphere and lower thermosphere from hawaii mf radar measurements 1 wind measurements in the mesosphere and lower thermosphere obtained with a medium frequency mf radar in hawaii 22 n 160 w spanning 16 years are employed to examine the intra annual and interannual variability of the mean and tidal motions at altitudes between 84 and 94 km intra annual periodicities range from 3 to 12 months with significant coherence in altitude and between the zonal and meridional components of each motion field interannual variations confirm the dominant periodicities identified previously at this site and elsewhere in particular the significant diurnal and less significant semidiurnal tidal responses at periods of 28 and 48 months amplitudes of these long period oscillations of the diurnal tide increase with altitude below 92 km and are larger than the amplitudes of the 12 month oscillations above 90 km phases of the 28 and 48 month oscillations show a downward progression with a slightly larger altitude variation in the meridional diurnal tide for the 28 month oscillation and a significantly larger altitude variation in the zonal diurnal tide for the 48 month oscillation the long and nearly continuous hawaii data set also enables characterization of the responses of the wind fields to the 11 year solar cycle both wind and tidal fields exhibit this periodicity but these responses display interesting and different relations to the phase of the solar cycle the 11 year oscillation of the meridional wind is nearly in phase with the solar cycle while the 11 year oscillation of the zonal wind is in approximate quadrature with the solar cycle the 11 year oscillations of the semidiurnal tidal amplitudes and the meridional diurnal amplitude are all in approximate quadrature with the solar cycle with the tidal amplitudes leading by 29 to 37 months while the 11 year oscillation of the zonal diurnal amplitude is somewhat nearer an antiphase than a quadrature relation to the solar cycle leading by 54 months

atmospheric tidal forcing of the zonal mean circulation the martian dusty atmosphere abstract classical atmospheric tidal theory has been used to compute the bilinear tidal zonal mean forcing per unit mass of the zonal mean meridional and zonal winds together with the tidal zonal mean heating per unit mass for the dusty martian atmosphere the convergences of the tidal eliassen palm ep flux have been computed for both clear and dusty atmospheric conditions including the special case of a dusty corridor in the summer southern subtropics that is meant to simulate the early stages of a planetary scale martian dust storm the calculation of the tidal ep zonal forcing differs from hamilton in that more realistic thermotidal forcings and basic state temperatures are used the zonal mean convergences of the tidal fluxes of heat and momentum are large during a martian great dust storm and should alter significantly the zonal mean circulation and its residual component driven by the zonal mean heating in particular the tidal forcing of the meridional wind which is an order of magnitude gr

tides in the mesopause region over antarctica comparison of whole atmosphere model simulations with ground based observations almost a quarter century ago first optical and radar observations from the south pole revealed rich dynamics unexpected from classical tidal theory a strong semidiurnal wind oscillation was detected near the mesopause implying substantial deviations from the classical view that the semidiurnal variation is dominated by the migrating tide subsequent systematic observations exhibited large seasonal variations of both the diurnal and semidiurnal tide with dramatic reduction in amplitude from summer to winter first numerical simulations with a realistic general circulation model extending into the lower thermosphere indicated the presence of nonmigrating tides with substantial amplitudes in the polar regions however direct model data comparisons have been limited to idealized linear models here whole atmosphere model wam simulations for january and july are compared with available wind climatologies based on multiyear radar observations at different locations in antarctica as well as with first summertime lidar measurements of temperature the diurnal tide simulation agrees well with most of the independent radar and satellite wind observations in both seasons the strong semidiurnal tide comprised of migrating and nonmigrating components is well reproduced in summer while in winter the model tends to overestimate the amplitudes over the continental edge besides model validation a self consistent numerical solution also enables cross validation of observations made with different instruments at different locales

tidal oscillations of the arctic upper mesosphere and lower thermosphere in winter the upper mesosphere and lower thermosphere of the northern polar cap was investigated using fabry perot interferometer measurements of the horizontal wind velocity in the lower thermosphere meridian scanning photometer observations of atomic oxygen green line brightness in the lower thermosphere and michelson interferometer records of the infrared meinel oh bands brightness and rotational temperature in the upper mesosphere tidal airglow oscillations in the absence of local solar heating were studied using a superposed epoch analysis of observations obtained around three new moon intervals november 9 22 1993 december 7 20 1993 and january 4 17 1994 in eureka 80 n tidal harmonics were uncovered with an iterated least chi squared fit and their existence in the data tested using a goodness of fit probability against a null hypothesis of no oscillations no single dominant tide was found at all times and altitudes of the winter arctic upper mesosphere and lower thermosphere the horizontal wind velocity of the lower thermosphere exhibited all the first three harmonics of the tide with the largest amplitude oscillations shown by the diurnal component of the meridional wave speed the atmospheric layer near the mesopause that contributes to the oh airglow emission experienced terdiurnal oscillations throughout the winter season theoretical polarization relations for evanescent tides considerations of energy density propagation with altitude and a day by day analysis of the zonal and meridional wind speed and temperature all indicate that the terdiurnal tide observed on november was an evanescent zonally symmetric tide other data indicate propagating tides migrating tides or a mixture of both

water and the viscosity of andesite melts the viscosity of a synthetic andesite like melt has been measured between 1010 and 1014 p for water contents in the range 0 3 5 wt the very slow kinetics of water exsolution over this viscosity range allowed the measurements to be made at 1 bar with a high precision after a steep viscosity decrease of 5 orders of magnitude for 1 wt h2o an additional 2 5 wt h2o causes a further viscosity decrease of only 2 orders of magnitude these viscosity decreases are qualitatively similar to those observed previously for more silica rich compositions the new data join smoothly with available high temperature measurements made at high pressures on water bearing andesite melts because the intrinsic effects of pressure are as small for water bearing as for water free samples the depressing effect of water on the viscosity of natural andesite melts can be estimated changes in water speciation as a function of either temperature or pressure do not seem to have marked effects on the viscosity although quantitative applications are not yet possible the configurational entropy theory accounts qualitatively for these features

causes of the longitudinal differences in the equatorial vertical e b drift during the 2013 ssw period as simulated by the time gcm during stratospheric sudden warming ssw periods large changes in the low latitude vertical drift have been observed at jicamarca as well as in other longitudinal sectors in general a strengthening of the daytime maximum vertical drift with a shift from prenoon to the afternoon is observed during the january 2013 stratospheric warming significant longitudinal differences in the equatorial vertical drift were observed at jicamarca the previously reported ssw behavior prevails however no shift of the daytime maximum drift was exhibited in the african sector using the national center for atmospheric research thermosphere ionosphere mesosphere electrodynamics general circulation model time gcm the possible causes for the longitudinal difference are examined the timing of the strong ssw effect in the vertical drift 15 20 january coincides with moderate geomagnetic activity the simulation indicates that approximately half of the daytime vertical drift increase in the american sector may be related to the moderate geophysical conditions kp 4 with the effect being negligible in the african sector the simulation suggests that the wind dynamo accounts for approximately 50 of the daytime vertical drift in the american sector and almost 100 in the african sector the simulation agrees with previous findings that the migrating solar tides and the semidiurnal westward propagating tide with zonal wave number 1 sw1 mainly contribute to the daytime wind dynamo and vertical drift numerical experiments suggest that the neutral wind and the geomagnetic main field contribute to the presence absence of a local time shift in the daytime maximum drift in the american african sector

vertical connection from the tropospheric activities to the ionospheric longitudinal structure simulated by a new earth s whole atmosphere ionosphere coupled model 1 this paper introduces a new earth s atmosphere ionosphere coupled model that treats seamlessly the neutral atmospheric region from the troposphere to the thermosphere as well as the thermosphere ionosphere interaction including the electrodynamics self consistently the model is especially useful for the study of vertical connection between the meteorological phenomena and the upper atmospheric behaviors as an initial simulation using the coupled model we have carried out a 30 day consecutive run in september the result reveals that the longitudinal structure of the f region ionosphere varies on a day to day basis in a highly complex way and that a four peak structure of the daytime equatorial ionization anomaly eia similar to the recent observations appears as an averaged feature the simulation reproduces and thus confirms the vertical coupling processes proposed so far with respect to the formation of the averaged eia longitudinal structure the excitation of solar nonmigrating tides in the troposphere their propagation through the middle atmosphere and the modulation of ionospheric dynamo which in turn affects eia generation the simulation result indicates that not only the ionospheric averaged longitudinal structure but also the day to day variation can be modulated significantly by the lower atmospheric effect

quasi biennial oscillation influence on long period planetary waves in the antarctic upper mesosphere 1 long period planetary wave data derived from meteor wind observations recorded over a 12 year period with the superdarn radar at halley antarctica are presented and compared with the phase of the quasi biennial oscillation qbo throughout the equatorial stratosphere enhanced planetary wave activity in the antarctic upper mesosphere is found during the summer months when the qbo in the equatorial upper stratosphere is westerly and during the late winter when the qbo in the upper stratosphere is easterly these quasi biennial enhancements in planetary wave activity coincide with a reduction in strength by up to 30 of the late winter eastward winds in the antarctic upper mesosphere in addition when the qbo is in the correct phase for enhanced planetary wave activity in the upper mesosphere above halley planetary wave activity measured in the upper mesosphere of the high latitude northern hemisphere is reduced and vice versa these results clearly indicate significant interhemispheric propagation of planetary waves from the winter to summer hemispheres observational evidence that the stratospheric qbo induces a strong enough qbo in the equatorial upper mesosphere to act as a gate to the interhemispheric propagation of these long period waves is discussed in light of these results

first results from the meteor radar at south pole a large 12 hour oscillation with zonal wavenumber one the first mesopause region ca 92 5 km wind measurements from the meteor radar at amundsen scott station at south pole are described measurements are made along four orthogonal azimuth directions approximately 2 from the geographic south pole a large 20 ms 1 oscillation in the northward wind is observed with 12 hour period and zonal wavenumber one a similar wave was observed during august 1 13 1992 at south pole by hernandez et al 1993 using optical methods the predominant semidiurnal tide in the atmosphere is migrating with the apparent motion of the sun with s 2 the s 1 oscillation is interpreted here to result from the nonlinear interaction between the migrating semidiurnal tide and a stationary wave with s 1 the present mechanism represents an alternative to the gravity wave driven pseudotide theory put forth by walterscheid et al 1986 to explain the occurrence of unexpectedly large semidiurnal tidal oscillations at high latitudes

middle and upper thermosphere density structures due to nonmigrating tides 1 density measurements from the seta satellites near 200 km during 1982 1984 and the champ and grace satellites between 350 and 550 km during 2002 2009 are used to investigate longitudinal structures in density due to nonmigrating tides and to evaluate performance of the recently created climatological tidal model of the thermosphere ctmt amplitudes for the diurnal and semidiurnal tidal components fall roughly in the range of 4 10 diurnal tides at middle and low latitudes are often characterized by wave 3 and or wave 4 structures consistent with the presence of the eastward propagating diurnal tides with zonal wave numberss 2 and s 3 de2 and de3 respectively and with expected seasonal variability based on previous works semidiurnal structures often reflect the presence of the eastward propagating tide withs 2 se2 which gives rise to wave 4 structures that have a more antisymmetric relationship between n and s hemispheres similarities in structures between different years underscore the fact that the thermosphere is subject to repeatable and reproducible forcing by upward propagating tides but there are also occasions where considerable departures from climatology occur wave 2 structures at high latitudes likely contain signatures of the eastward propagating diurnal tide withs 1 de1 and the zonally symmetric s 0 semidiurnal oscillation s0 propagating upwards from below but these and other waves that produce wave 2 can also be forced in situ by high latitude processes the ctmt captures the salient features of the observations at middle and low latitudes although with lower amplitudes that are likely due to phase cancelation effects resulting from averaging over multiple years 2002 2006 we propose that some discrepancies between the ctmt and our observational results may be associated with wave components arising in situ in the thermosphere as the result of nonlinear tide tide interactions and plasma neutral interactions the latter being especially prominent at high latitudes where the displaced geomagnetic frame is particularly influential modeling studies are required to validate these proposed mechanisms however

upper atmosphere of mars up to 120 km mars global surveyor accelerometer data analysis with the lmd general circulation model 1 mars global surveyor mgs aerobraking accelerometer density measurements are analyzed with the use of the general circulation model gcm at the laboratoire de meteorologie dynamique lmd mgs constant altitude density data are used obtaining longitudinal wavelike structures at fixed local times which appear to be dominated by low zonal wave number harmonics comparisons with simulated data for different seasons and latitudinal bands at constant altitude are performed excellent agreement is obtained between the simulated and observational data for low latitudes with accuracy in both mean and zonal structure higher latitudes show a reduction in agreement between gcm results and mgs data comparisons that result in good agreement with the observational data allow for the study of wave composition in the mgs data in particular the excellent agreement between the simulations and the data obtained at 115 km during areocentric longitude ls 65 allows the extraction of the major contributors to the signature with the eastward propagating diurnal waves of wave numbers one to three being the major players significant contributions are also obtained for eastward propagating semidiurnal waves of wave numbers two three and five and diurnal wave number five a sensitivity study is performed to delineate the effects of the near ir tidal forcing of the upper atmosphere on the wave content at those heights simulations without this forcing yield reduced amplitudes for diurnal eastward propagating waves two and three along with a more latitudinally symmetric response for these two components as well as for diurnal eastward propagating wave number one

large scale waves in the upper mesosphere at antarctic high latitudes upper mesosphere combined optical measurements of wind and temperature fields at amundsen scott station south pole and wind radar measurements at scott base 78 s 167 e show the presence of large scale waves in this region of the atmosphere at amundsen scott the largest amplitude wave observed with sub diurnal periodicity appears with a frequency near 2 4 day 10 1 hour period with a westward phase progression of wavenumber one the presence of a wave with this periodicity is confirmed by the observations at scott base the combination of the experimentally found period phase progression associated small temperature oscillations and theoretical considerations lead to the interpretation of this wave as a lamb wave the present combination of spatially resolved optical measurements and radar measurements illustrates the value of multiple station and multiple technique observations in elucidating the upper mesosphere dynamical state as well as the properties of the waves propagating through the medium where the observations are being made

quasi biennial modulation of the semidiurnal tide in the upper mesosphere above halley antarctica we present an analysis of a long term archive of horizontal wind data derived from meteor wind observations from a superdarn radar at halley antarctica 76s 27w systematic differences between the 12 hour component in the meridional wind and the climatological mean are observed showing evidence of a quasi biennial modulation of the high latitude semidiurnal tide in the upper mesosphere the amplitude of the observed tides is enhanced when the equatorial stratospheric quasibiennial oscillation above 10 hpa is westerly this enhancement is greatest in the summertime tidal amplitudes when the zonal wavenumber one s 1 nonmigrating component dominates the semidiurnal wind field and is coincident with an enhancement of the summertime planetary wave activity in the upper mesosphere these observations strongly support the hypothesis that the s 1 component of the semidiurnal tide observed at high latitudes is due to a non linear interaction between the migrating s 2 semidiurnal tide and quasi stationary s 1 planetary waves

long term observations of the wind field in the antarctic and arctic mesosphere and lower thermosphere at conjugate latitudes 1 mean winds semidiurnal and diurnal tides and trends and long period oscillations spanning a solar cycle from early 1999 through june 2010 measured by medium frequency mf radars at conjugate antarctic and arctic latitudes syowa antarctica 69 s 39 6 e and andenes norway 69 3 n 16 e are described and compared zonal mean winds are stronger and more uniform from year to year over the antarctic with a stronger eastward winter jet spanning the range of altitudes presented 70 to 96 km the summer westward jet is also stronger and maximizes at higher altitudes over the antarctic than over the arctic the eastward winter jet over the arctic while generally weaker exhibits a localized maximum in late winter at 2 to 3 year intervals meridional mean winds likewise achieve somewhat stronger maxima at higher altitudes over the antarctic than over the arctic semidiurnal tide amplitudes are typically somewhat larger over the antarctic and similar in the two components with maxima at 85 km or above and narrow responses that tend to cluster from february to may and september to november over the antarctic and from december to february and june to september over the arctic zonal diurnal tide amplitudes are quite similar between the sites with maxima extending from 70 to 90 km and slightly stronger over the antarctic meridional diurnal amplitudes display more significant growth with altitude achieve stronger maxima at the highest altitudes presented and typically exhibit a single and narrow maximum during december to february over the antarctic and double maxima from may to september over the arctic also discussed are trends and long period oscillations over a solar cycle observed in these mean and tidal wind fields

nonlinear interactions in the upper atmosphere the s 1 and s 3 nonmigrating semidiurnal tides 1 a semidiurnal oscillation with zonal wave number s 1 has been observed over the south pole and longitudinal variations of the semidiurnal tide at northern midlatitudes have been ascribed to the presence of nonmigrating tides a three dimensional nonlinear spectral model is used herein to study nonlinear wave wave interaction as a possible mechanism for the generation of nonmigrating tides in the mesosphere and lower thermosphere in particular the s 1 and s 3 nonmigrating semidiurnal tides are studied as a by product of the nonlinear interaction between the semidiurnal s 2 migrating tide and a stationary s 1 planetary wave in the lower and middle atmosphere this process is found to yield significant amplitudes 10 30 m s 1 of the nonmigrating semidiurnal components with s 1 and s 3 in the upper atmosphere comparisons with monthly nonmigrating tidal amplitudes and phases at 95 km derived from high resolution doppler imager and wind imaging interferometer wind measurements from uars show good agreement with the model simulations the effect of the dissipating nonmigrating tides on the zonal mean circulation is found to reinforce that of the migrating component contributing 10 20 m s 1 to the zonal wind field and 5 10 m s 1 to the mean meridional wind field several other wave components are generated through nonlinear interactions including 6 hour tides with zonal wave numbers s 0 1 4 and a semidiurnal oscillation with s 6 these wave components have amplitudes in the range 6 30 m s 1 in the 110 150 km height regime the combination of all nonmigrating tides together with the migrating component suggests significant longitudinal variations in the semidiurnal tide in the e region which may be important for studies of the quiet time generation of ionospheric electric fields by the dynamo mechanism

dust devils on mars columnar cone shaped and funnel shaped clouds rising 1 to 6 kilometers above the surface of mars have been identified in viking orbiter images they are interpreted as dust devils confirming predictions of their occurrence on mars and giving evidence of a specific form of dust entrainment

simultaneous mesospheric wind measurements near south pole by optical and meteor radar methods simultaneous and co located measurements of mesospheric winds near south pole by high resolution optical and meteor radar methods show that these two methods determine very similar motions at slightly different heights of observation the measured atmospheric motions by the two techniques show that a the mean wind during 12 days in june 1995 was found to have a 7 m s amplitude flowing towards the 5 e longitude direction the latter direction is different from the 30e direction found earlier during august 1991 and 1992 b the observed dominant oscillations in the wind at both heights of observation are those of zonal wavenumber one character westward phase propagation was determined for the observed short period 0 hours oscillations and eastward phase propagation for the longer period 3 days oscillations respectively because of the neighboring heights of observation by the optical and meteor radar methods the in situ vertical wavelengths of propagation of the observed waves have been determined to be greater than 100 km for the 10 hr oscillations and near 65 km for the longer period oscillations with this new information we are able to independently establish the earlier assignment of the nearly 10 hr oscillations as the different meridional modes of a zonal wavenumber one lamb wave the determined vertical wavelength and eastward phase progression of the longer periodicity waves indicate these oscillations are likely to be the gravest inertio gravity wave which has the appropriate equivalent depths at these periods of oscillation the simultaneous absence of statistically significant kinetic temperature and optical tracer emission rate oscillations at the frequencies corresponding to the wind motions provides independent support to the earlier deductions on the ability of the atmosphere near the rotational poles to support only certain zonal character oscillations

intra annual variability of the low latitude ionosphere due to nonmigrating tides 1 in situ plasma density measurements from the champ satellite between about 350 420 km altitude are used to delineate intra annual variations in the longitudinal structure of the f region ionosphere it is shown that the longitude structures during mid day local times are dominated by the space based longitudinal wavenumbers ks 2 4 and 3 in january july and december respectively these conform to the same dominating ks values characterizing solar thermal tide zonal winds in the dynamo region namely the westward propagating semidiurnal tide with planetary fixed zonal wavenumber s 4 sw4 and the eastward propagating diurnal tides with s 3 de3 and s 2 de2 respectively de3 is the dominating tide during the other months the results presented indicate that nonmigrating tides other than de3 may significantly impact the longitudinal structure of the low latitude ionosphere during certain months

mesospheric standing waves near south pole optical measurements of mesospheric winds near south pole during august 1996 show the presence of large scale standing waves with periods of 51 3 hr and 107 hr respectively in addition a 11 6 hr period zonal wavenumber one oscillation with a westward phase progression was also observed the direction of the observed mean wind has changed nearly 60 westward from the typical wind direction observed during the same month in previous years the direction of the presently observed mean wind is nearly parallel to wind direction of the 51 3 hr standing oscillation suggesting an interaction between the mean wind field and the wave during this observation based on the simultaneous observation at scott base of an uncommon wave with 11 53 hr periodicity with short 20 km vertical wavelength of propagation the 11 6 hr wave observed from south pole can be identified as a zonal wavenumber one inertio gravity mode of oscillation because of the transience of this wave and its closeness to the inertial period we also discuss another approach to the interpretation of such waves as possible forced oscillations

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

effects of vertically propagating thermal tides on the mean structure and dynamics of mars lower thermosphere 1 a general circulation model of mars atmosphere is used to elucidate the effects of vertically propagating thermal tides excited near the surface on the zonal mean density temperature and wind structure of mars atmosphere between 90 and 160 km the effects are substantial and amount to order 10 40 10 50 k and 50 160 m s 1 respectively at these altitudes under low dust conditions dust visible optical depth 0 3 these induced changes in the zonal mean structure are dominated by the non migrating tides of particular note are the mean density perturbations which represent an important consideration for modeling of the aerobraking region 100 170 km

short term variation of the s 1 nonmigrating semidiurnal tide during the 2002 stratospheric sudden warming 1 in this study the ncar thermosphere ionosphere mesosphere electrodynamics general circulation model time gcm is used to examine short term changes in the global structure of the migrating and s 1 nonmigrating semidiurnal tides in a model run approximating the 2002 southern hemisphere stratospheric sudden warming the time gcm is found to resolve an s 1 nonmigrating semidiurnal tide with latitudinal structure similar to that of prior studies and with global structure in the mlt region strongly correlated with southern hemisphere planetary wave 1 pw1 wave events prior to equinox comparison with a control run with no planetary wave activity eliassen palm flux and correlation analysis of the s 1 semidiurnal tide structure suggest that the wave propagates from the source region in the winter hemisphere stratosphere into both the summer and winter lower thermospheres the amplitudes of the migrating semidiurnal tide in the southern hemisphere are anticorrelated with the nonmigrating tide suggesting significant energy loss due to nonmigrating tidal generation a result not previously seen the amplitude of the s 1 nonmigrating semidiurnal tide from time gcm is also compared with data from the south pole meteor radar system while the observations show bursts of nonmigrating tidal activity correlated to pw1 activity of comparable amplitudes to the model results these events do not always appear at the same times as those in the model this suggests that while the processes generating the nonmigrating tide in time gcm are realistic the time gcm run itself displays differences in time evolution compared to the observations during this time