estimates of momentum flux in the mesosphere and lower thermosphere over adelaide australia from march 1985 to february 1986 in order to balance the momentum budget of the mesosphere it is necessary to have a source of momentum in that region to drive the observed meridional circulation thus measurements of mesospheric momentum flux are fundamental to our understanding of the dynamics of the mesosphere the first measurements of momentum flux in this region did not adequately take into account the effect of aspect sensitivity on the effective pointing angle of a radar beam and were therefore incorrect by some factor in this paper a method of determining the pointing direction of a radar beam from the spatial correlation function of the echoes is presented and applied to a data set that spans a year beginning in march 1985 momentum fluxes during twelve 4 day periods thoughout the year are calculated using these improved pointing angle calculations and a new outlier rejection scheme the results representing a significant expansion of the worldwide mesospheric momentum flux data set are then presented

large amplitude mountain waves in the mesosphere observed on 21 june 2014 during deepwave 1 wave development scales momentum fluxes and environmental sensitivity

a gravity wave drag matrix for complex terrain abstractwe propose a simplified scheme to predict mountain wave drag over complex terrain using only the regional average low level wind components u and v the scheme is tuned and tested on data f

mobility of arsenic and trace element inventories in sediment cores from masuda city southwestern japan the vertical distribution of arsenic and other trace and major elements has been studied in four sediment cores from masuda city nagashima and okite in the shimane prefecture of southwestern japan the sediment cores were also subjected to leaching techniques and 14c dating the stratigraphic sequences in the cores consist of silt and sandy silt at top passing downward into gray to black clays elevated values of as pb zn cu ni cr and v are present in several horizons while abundances of these elements tend to be higher in the black and gray clays probably due to adsorption onto clay sediments higher concentrations of fe and total sulfur ts occur in black clays the correlations of the trace metals with iron suggest their adsorption onto fe oxy hydroxides whereas correlations with sulfur in some cores indicate that they were precipitated as fe sulfides age determinations suggest that clay horizons at 5 m depth were deposited at around 5 000 and 6 000 years bp 14c ages during the transgressive phase of sea level change the results of the leaching techniques in the core samples show that higher amounts of as were extracted with deionized water even at neutral ph as can be released from sediments to groundwater and therefore groundwater pollution is a concern in masuda city and the surrounding area

secondary gravity wave generation over new zealand during the deepwave campaign multiple events during the deep propagating gravity wave experiment measurement program revealed mountain wave mw breaking at multiple altitudes over the southern island of new zealand these events were measured during several research flights from the national science foundation national center for atmospheric research gulfstream v aircraft utilizing a rayleigh lidar an na lidar and an advanced mesospheric temperature mapper simultaneously a flight on 29 june 2014 observed mws with horizontal wavelengths of 80 120 km breaking in the stratosphere from 10 to 50 km altitude a flight on 13 july 2014 observed a horizontal wavelength of 200 240 km mw extending from 20 to 90 km in altitude before breaking data from these flights show evidence for secondary gravity wave sgw generation near the breaking regions the horizontal wavelengths of these sgws are smaller than those of the breaking mws indicating a nonlinear generation mechanism these observations reveal some of the complexities associated with mw breaking and the implications this can have on momentum fluxes accompanying sgws over mw breaking regions

vertical geochemical variations and arsenic mobilization in the shallow alluvial aquifers of the chapai nawabganj district northwestern bangladesh implication of siderite precipitation core sediments from three disturbed boreholes jor ghat and raj and two undisturbed boreholes dw1 and dw2 were collected in the study area of the chapai nawabganj district of northwestern bangladesh for geochemical analyses in the study area groundwater samples from fourteen as contained private wells and five nested piezometers at both the dw1 and dw2 boreholes were also collected and analyzed the groundwater arsenic concentrations in the uppermost aquifer 10 40 m of depth range from 3 to 315 g l mean 47 73 73 41 g l while the arsenic content in sediments range from 2 to 14 mg kg mean 4 36 3 34 mg kg an environmental scanning electron microscope esem with an energy dispersive x ray spectrometer was used to investigate the presence of major and trace elements in the sediments groundwaters in the study area are generally the ca hco3 type with high concentrations of as but low levels of fe mn no3 and so 4 2 the concentrations of as fe mn decrease with depth in the groundwater showing vertical geochemical variations in the study area statistical analysis clearly shows that as is closely associated with fe and mn in the sediments of the jor core r 0 87 p 0 05 for fe and r 0 78 p 0 05 for mn and ghat core r 0 95 p 0 05 for fe and r 0 93 p 0 05 for mn while as is not correlated with fe and mn in groundwater the comparatively low fe and mn concentrations in some groundwater and the esem image revealed that siderite precipitated as a secondary mineral on the surface of the sediment particles the correlations along with results of sequential extraction experiments indicated that reductive dissolution of feooh and mnooh represents a mechanism for releasing arsenic into the groundwater

ocean cooling constraints from changes in earth s dynamic oblateness j2 and altimetry 1 dynamic oblateness j2 observations reflect changes in the latitudinal distribution of mass within the earth system and hence can give insights into processes involving water transport and sea level rise we seek to use records of j2 variations deduced from satellite laser ranging together with altimetry results to provide an independent geodetic constraint on changes in ocean heat content ohc we show that the size and signature of the j2 signal presented here do not support a recently published report of rapid oceanic heat loss beginning in 2003 which was subsequently attributed to argo and other instrumental bias effects our results are consistent with recent findings of a flattening of the ohc trend at this time inferred from the bias corrected argo data and demonstrate that j2 observations in combination with other observational and model data types can provide useful constraints for monitoring and validating ongoing changes in the earth system

surprising return of deep convection to the subpolar north atlantic ocean in winter 2007 2008 in the process of open ocean convection in the subpolar north atlantic ocean surface water sinks to depth as a distinct water mass the characteristics of which affect the meridional overturning circulation and oceanic heat flux in addition carbon is sequestered from the atmosphere in the process in recent years this convection has been shallow or non existent which could be construed as a consequence of a warmer climate here we document the return of deep convection to the subpolar gyre in both the labrador and irminger seas in the winter of 2007 2008 we use profiling float data from the argo programme to document deep mixing analysis of a variety of in situ satellite and reanalysis data shows that contrary to expectations the transition to a convective state took place abruptly without going through a phase of preconditioning changes in hemispheric air temperature storm tracks the flux of fresh water to the labrador sea and the distribution of pack ice all contributed to an enhanced flux of heat from the sea to the air making the surface water sufficiently cold and dense to initiate deep convection given this complexity we conclude that it will be difficult to predict when deep mixing may occur again

a coordinated investigation of the gravity wave breaking and the associated dynamical instability by a na lidar and an advanced mesosphere temperature mapper over logan ut 41 7 n 111 8 w the impacts of gravity wave gw on the thermal and dynamic characteristics within the mesosphere lower thermosphere especially on the atmospheric instabilities are still not fully understood in this paper we conduct a comprehensive and detailed investigation on one gw breaking event during a collaborative campaign between the utah state university na lidar and the advanced mesospheric temperature mapper amtm on 9 september 2012 the amtm provides direct evidence of the gw breaking as well as the horizontal parameters of the gws involved while the na lidar s full diurnal cycle observations are utilized to uncover the roles of tide and gws in generating a dynamical instability layer by studying the changes of the oh layer peak altitude we located the wave breaking altitude as well as the significance of a 2 h wave that are essential to this instability formation by reconstructing the mean fields tidal and gw variations during the wave breaking event we find that the large amplitude gws significantly changed the brunt vaisala frequency square and the horizontal wind shear when superimposed on the tidal wind producing a transient dynamic unstable region between 84 km and 87 km around 11 00 ut that caused a subsequent small scale gw breaking

identifying the causes of sea level change global mean sea level change has increased from a few centimetres per century over recent millennia to a few tens of centimetres per century in recent decades a review of the latest work shows that global mean sea level rise is unlikely to exceed one metre over the twenty first century but regional departures from this global mean could reach several decimetres

seasonal variation of momentum flux in the mesosphere observed with the mu radar we have regularly monitored mesospheric winds at 60 85km for three years with the mu radar 35 n 136 e and have found that the variance of wind velocity fluctuations for periods from 5 min to 2 hr shows a semi annual variation with a significant peak in summer centered in july and irregular enhancements in winter the zonal momentum flux induced by gravity waves shows eastward and westward maxima in july august and december february respectively typical eastward accelerations at the 70km altitude range from 7 to 13 m s day and from 8 to 11 m s day in summer and winter respectively which agree fairly well with theoretical predictions

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

mesospheric momentum fluxes observed by the mst radar at poker flat alaska abstract an analysis of the wave motions observed with the poker flat mst radar during the winter summer and fall of 1986 is presented in this paper monthly and daily mean winds momentum fluxes and velocity variances are investigated in detail while several features are in agreement with previous measurements some significant differences also are found to exist in our observations monthly mean horizontal winds between 82 and 89 km have amplitudes of 20 40 m s 1 westward and 10 25 m s 1 southward in july and august in fall and winter the horizontal winds between 58 and 75 km are weaker and essentially eastward monthly mean vertical velocities are predominantly downward at 0 3 m s 1 which implies a vertical wave energy flux of 0 1 w m 2 higher than that estimated at low latitudes monthly mean horizontal variances are 1600 m2 s 2 in summer and 600 m2 s 2 in fall and winter with vertical variances 3 m2 s 2 monthly mean zonal and meridional momentum fluxes contributed predominantly by wa

numerical modeling of a multiscale gravity wave event and its airglow signatures over mount cook new zealand during the deepwave campaign a 2d nonlinear compressible model is used to simulate a large amplitude multiscale mountain wave event over mt cook nz observed as part of the deepwave campaign and to investigate its observable signatures in the hydroxyl oh layer the campaign observed the presence of a x 200km mountain wave as part of the 22nd research flight with amplitudes of 20k in the upper stratosphere that decayed rapidly at airglow heights advanced mesospheric temperature mapper amtm showed the presence of small scale 25 28km waves within the warm phase of the large mountain wave the simulation results show rapid breaking above 70km altitude with the preferential formation of almost stationary vortical instabilities within the warm phase front of the mountain wave an oh airglow model is used to identify the presence of small scale wave like structures generated in situ by the breaking of the mountain wave that are consistent with those seen in the observations while it is easy to interpret these feature as waves in oh airglow data a considerable fraction of the features are in fact instabilities and vortex structures simulations suggest that a combination of a large westward perturbation velocity and shear in combination with strong perturbation temperature gradients cause both dynamic and convective instability conditions to be met particularly where the wave wind is maximized and the temperature gradient simultaneously minimized this leads to the inevitable breaking and subsequent generation of smaller scale waves and instabilities which appear most prominent within the warm phase front of the mountain wave

recent western south atlantic bottom water warming 1 potential temperature differences are computed from hydrographic sections transiting the western basins of the south atlantic ocean from 60 s to the equator in 2005 2003 and 1989 1995 while warming is observed throughout much of the water column the most statistically significant warming is about 0 04 c in the bottom 1500 dbar of the brazil basin with similar but less statistically significant warming signals in the abyssal argentine basin and scotia sea these abyssal waters of antarctic origin spread northward in the south atlantic the observed abyssal argentine basin warming is of a similar magnitude to that previously reported between 1980 and 1989 the brazil basin abyssal warming is similar in size to and consistent in timing with previously reported changes in abyssal southern inflow and northern outflow the temperature changes reported here if they were to hold throughout the abyssal world ocean would contribute substantially to global ocean heat budgets

a high resolution salinity time series 1993 2012 in the north atlantic from argo and altimeter data the study of salinity changes has been hampered by the lack of temporal and spatial resolution of the observations in order to improve the spatial and temporal distribution of salinity observations we used the gravest empirical mode gem technique to calculate high resolution salinity distributions as a function of dynamic height for the period 1993 2012 this technique combined argo and altimeter data to exploit the relationship between t s profiles and dynamic height in the north atlantic the method was valid in the upper 700 m mainly at and near the pathways of the north atlantic current nac but failed in regions with weak stratification or with ambiguities in the t s relationships coherent multiannual large scale variability was observed with many features present in all regions albeit with weaker amplitudes in the eastern basins some of the interannual features in the northeastern atlantic basins were unrelated to the variability further south and west pointing to an occasional advection of subtropical water in the eastern atlantic origin and advection of salinity anomalies with the nac from the north american basin into the western subpolar north atlantic are correlated with the state of the north atlantic oscillation nao and dampened by the surface freshwater fluxes other mechanisms influencing the salinity pattern are the changing location of the subpolar front also related to the nao the large multiyear variability in the 20 year time series obscured any potential trends caused by global warming only the rockall trough showed a salinity increase of 0 03 per decade

upper ocean thermal structure and the western north pacific category 5 typhoons part ii dependence on translation speed abstract using new in situ ocean subsurface observations from the argo floats best track typhoon data from the u s joint typhoon warning center an ocean mixed layer model and other supporting datasets this work systematically explores the interrelationships between translation speed the ocean s subsurface condition characterized by the depth of the 26 c isotherm d26 and upper ocean heat content uohc a cyclone s self induced ocean cooling negative feedback and air sea enthalpy fluxes for the intensification of the western north pacific category 5 typhoons based on a 10 yr analysis it is found that for intensification to category 5 in addition to the warm sea surface temperature generally around 29 c the required subsurface d26 and uohc depend greatly on a cyclone s translation speed it is observed that even over a relatively shallow subsurface warm layer of d26 60 70 m and uohc 65 70 kj cm 2 it is still possible to have a sufficient enthalpy flux to intensify the storm to category 5

on the nature of short period mesospheric gravity wave propagation over halley antarctica 1 as part of a collaborative program between british antarctic survey and utah state university measurements were made using an all sky airglow imager located at the u k halley station 76 s 27 w during the 2000 and 2001 austral winter seasons from april through to early september a co located imaging doppler interferometer was utilized to obtain coincident wind measurements for a total of 171 wave events this study comprises the first detailed climatological investigation of the propagation nature freely propagating doppler ducted or evanescent of individual quasi monochromatic short period wave events at a high southern latitude distributions of the derived vertical wavelength exhibit an interquartile range from 16 48 km with a median vertical wavelength of 21 km the majority of the wave events were found to be freely propagating waves with only 5 exhibiting a clear doppler ducted signature while 15 of the waves were found to be evanescent in nature although no coincident temperature measurements were available subsequent saber temperature measurements suggest that up to 28 of the measured temperature profiles are capable of providing a ducted environment for the observed wave field this is in sharp contrast to findings at mid and low latitudes where these waves have been shown to be prone to doppler ducted motion it is suggested that the relatively weak wind field and associated tidal wind amplitudes over halley are not capable of forming a significant doppler ducted region to sustain a substantial amount of ducted waves belonging to the detectable spectrum of the airglow imager as these wind fields are comparable to wind fields found at other polar latitudes we hypothesize that the majority of short period gravity waves observed in the polar mesosphere are freely propagating and thus an important source of energy transfer into the mlt region

changes in the velocity structure of the greenland ice sheet using satellite radar interferometry observations of greenland we detected widespread glacier acceleration below 66 north between 1996 and 2000 which rapidly expanded to 70 north in 2005 accelerated ice discharge in the west and particularly in the east doubled the ice sheet mass deficit in the last decade from 90 to 220 cubic kilometers per year as more glaciers accelerate farther north the contribution of greenland to sea level rise will continue to increase

seasonal variations of the gravity wave momentum flux in the antarctic mesosphere and lower thermosphere airglow imager and dynasonde imaging doppler interferometer idi radar wind measurements at halley station antarctica 75 6degreess 26 6degreesw have been used to estimate the seasonal variation of the vertical fluxes of horizontal momentum carried by high frequency atmospheric gravity waves the cross correlation coefficients between the vertical and horizontal wind perturbations were calculated from sodium na airglow imager data collected during the austral winter seasons of 2000 and 2001 these were combined with wind velocity variances from coincident radar measurements to estimate the daily averaged upper limit of the vertical flux of horizontal momentum due to gravity waves the resulting momentum flux at the na airglow altitudes while displaying a large day to day variability showed a marked rotation from the northwest to the southeast throughout the winter season calculations show that this rotation is consistent with seasonal changes in the wind field filtering of gravity waves below the na airglow region the calculations also indicate that while the magnitude of the meridional wind is small this filtering leads to the observed seasonal changes in the meridional momentum flux

momentum flux estimates accompanying multiscale gravity waves over mount cook new zealand on 13 july 2014 during the deepwave campaign observations performed with a rayleigh lidar and an advanced mesosphere temperature mapper aboard the national science foundation national center for atmospheric research gulfstream v research aircraft on 13 july 2014 during the deep propagating gravity wave experiment deepwave measurement program revealed a large amplitude multiscale gravity wave gw environment extending from 20 to 90 km on flight tracks over mount cook new zealand data from four successive flight tracks are employed here to assess the characteristics and variability of the larger and smaller scale gws including their spatial scales amplitudes phase speeds and momentum fluxes on each flight a large scale mountain wave mw having a horizontal wavelength 200 300 km was observed smaller scale gws over the island appeared to correlate within the warmer phase of this large scale mw this analysis reveals that momentum fluxes accompanying small scale mws and propagating gws significantly exceed those of the large scale mw and the mean values typical for these altitudes with maxima for the various small scale events in the range 20 105 m2 s 2

spatial distribution of major and trace elements in shallow reservoir sediments an example from lake waco texas sediment geochemistry of a shallow 6 m average reservoir lake waco was evaluated for the spatial distribution of major and trace elements sixty bottom and core samples along a 21 km transect within the reservoir 18 overbank sediment samples and 8 rock types in the drainage area were collected and analyzed for major al ca fe and trace elements as ba cr cu hg mn ni pb sr v zn elemental concentrations in the reservoir sediments closely correspond to concentrations in the regional rocks and represent a mixture of overbank sediment composition of the tributaries elemental concentrations were statistically regressed against al concentrations in order to establish regional baseline levels and thereby distinguish natural from anthropogenic sources spatial geochemical trends considered in terms of element to al ratio versus v to al ratio relate to the natural and anthropogenic sources contributing to the elemental concentrations the spatial elemental distribution in the reservoir which receive sediments from two mineralogically contrasting basins reflect textural and mineralogical transition within the reservoir and suggest a progressive mixing of sediment from the tributaries the spatial elemental distribution and sediment texture suggest that the sediment source which determines the sediment type has a greater influence on the major and trace element distributions in shallow reservoir sediments than bathymetry

concentric gravity waves in the mesosphere generated by deep convective plumes in the lower atmosphere near fort collins colorado 1 gravity waves in the mesopause region 80 105 km may induce perturbations in oh meinal band emissions at 87 km these perturbations can be observed by ground based oh airglow imagers in this paper we present observations of concentric gravity waves cgw by the all sky oh imager at yucca ridge field station 40 7 n 104 9 w near fort collins colorado we find that expanding rings of concentric gravity waves were observed on 9 out of 723 clear nights from 2003 to 2008 in particular on 11 may 2004 concentric rings were observed for 1 5 h with nearly perfect circular rings entirely in the field of view during the first 30 min the centers of the concentric rings occurred at the geographic locations of two strong convective plumes which were active in the troposphere 1 h earlier we measured the horizontal wavelengths and periods of these gravity waves as functions of both radius and time these results agreed reasonably well with the internal boussinesq gravity wave dispersion relation with an assumed zero background wind similarly for the other 8 cases strong convective plumes occurred prior to the cgw observations near the apparent center of each of the arcs or rings for the 7 out of the 9 cases radiosonde data were available up to z 30 35 km these data showed that the wind speeds from the tropopause to 30 35 km were smaller than 20 30 m s because 8 of the 9 cases occurred when the total horizontal mean winds were weak and because the horizontal winds below 87 km were less than 20 m s on 11 may 2004 according to radiosonde and time gcm model data we postulate that weak background horizontal winds are likely a necessary condition for gravity waves excited from convective overshooting to be observed as concentric arcs or rings in the oh layer

numerical modeling of the excitation propagation and dissipation of primary and secondary gravity waves during wintertime at mcmurdo station in the antarctic

characteristics of gravity waves in the mesosphere observed with the middle and upper atmosphere radar 1 momentum flux we observed wind motions from 60 to 90 km altitudes with the mu radar 35 n 136 e in the four observation periods october 1986 june 1987 july 1990 and january february 1991 mean wind profiles were fairly consistent with results of kyoto meteor radar observations 35 n 136 e collected in 1983 1985 at 80 to 110 km altitudes and zonal mean winds generally agreed well with cira 1986 except for the profiles below 70 km in january february 1991 although discrepancy of amplitudes sometimes ranged up to 10 to 20 m s characteristics of frequency spectra of radial wind velocities were basically similar among results determined in four observation periods that is oblique spectra had a logarithmic slope of about 5 3 in the frequency range lower than 4 5 10 4 s 1 gravity waves with periods longer than 20 50 min to 5 hours the lowest limit of the spectral analysis were found to carry a large part of the zonal momentum flux while a dominant frequency component was not detected for the meridional flux zonal and meridional drag of mean winds induced by the gravity wave with periods from 5 min to 8 10 hours were 51 m s d and 4 m s d in june at 75 km and 4 0 m s d and 7 4 m s d in october at 70 km respectively the major part of the drag force was also found in the wave component with periods larger than 30 min the day to day variation in the zonal momentum flux showed a good correlation with the vertical shear of the zonal mean wind which suggests effects of the gravity wave activities on mean wind fields or the effect of shear variation on the gravity wave activity

the origin of stationary planetary waves in the upper mesosphere abstract satellite observations indicate that quasi stationary planetary waves often exist to at least 100 km in the winter mesosphere waves are also seen in the summer upper mesosphere a three dimensional numerical model was used to simulate these waves and to diagnose the physical processes involved the waves simulated in the model closely resemble observed waves several model runs that isolate specific processes are used to determine the relative importance of two forcing mechanisms in the model planetary waves that propagate from below are significantly damped at the altitude where gravity wave drag becomes large about 75 km in the winter midlatitudes or below if a reversal in the mean wind is encountered momentum forcing associated with breaking gravity waves that have been filtered by planetary scale wind variations below acts to generate planetary waves in the middle and upper mesosphere the amplitude from in situ forcing by gravity wave breaking exceeds the amplitude from the upward prop

a decade of acoustic thermometry in the north pacific ocean 1 over the decade 1996 2006 acoustic sources located off central california 1996 1999 and north of kauai 1997 1999 2002 2006 transmitted to receivers distributed throughout the northeast and north central pacific the acoustic travel times are inherently spatially integrating which suppresses mesoscale variability and provides a precise measure of ray averaged temperature daily average travel times at 4 day intervals provide excellent temporal resolution of the large scale thermal field the interannual seasonal and shorter period variability is large with substantial changes sometimes occurring in only a few weeks linear trends estimated over the decade are small compared to the interannual variability and inconsistent from path to path with some acoustic paths warming slightly and others cooling slightly the measured travel times are compared with travel times derived from four independent estimates of the north pacific 1 climatology as represented by the world ocean atlas 2005 woa05 2 objective analysis of the upper ocean temperature field derived from satellite altimetry and in situ profiles 3 an analysis provided by the estimating the circulation and climate of the ocean project as implemented at the jet propulsion laboratory jpl ecco and 4 simulation results from a high resolution configuration of the parallel ocean program pop model the acoustic data show that woa05 is a better estimate of the time mean hydrography than either the jpl ecco or the pop estimates both of which proved incapable of reproducing the observed acoustic arrival patterns the comparisons of time series provide a stringent test of the large scale temperature variability in the models the differences are sometimes substantial indicating that acoustic thermometry data can provide significant additional constraints for numerical ocean models

upper equatorial pacific ocean current and salinity variability during the 1996 1998 el nino la nina cycle the recent el nino la nina cycle exhibited striking patterns of current and salinity variability in the upper equatorial pacific ocean this evolution is described from mid 1996 through 1998 using a remarkable data set of 35 meridional conductivity temperature depth ctd acoustic doppler current profiler adcp sections along with buoy data the sections nominally from 8 s to 8 n between 165 e and 95 w were occupied over the course of 27 months a wide range of current variability was sampled with currents that appeared or disappeared some time during the cycle including an equatorially trapped eastward surface current the equatorial undercurrent the northern branch of the south equatorial current and the north equatorial countercurrent basin wide interannual changes in upper ocean and pycnocline zonal transports were as large as 64 32 106 m3 s 1 changes in the salinity structure included a deep and fresh mixed layer in the central equatorial pacific that built up during the el nino and was then disrupted by upwelled salty water with the onset of la nina a very fresh mixed layer observed in the eastern equatorial pacific late in the el nino and a reduction in the strength of the meridional equatorial salinity gradient within the pycnocline to one third of the usual value during the el nino finally the zonal transports above the thermocline from 5 s to 5 n were well correlated with the rate of change of warm water volume west of the individual ctd adcp sections

measurements of time variable gravity show mass loss in antarctica using measurements of time variable gravity from the gravity recovery and climate experiment satellites we determined mass variations of the antarctic ice sheet during 2002 2005 we found that the mass of the ice sheet decreased significantly at a rate of 152 80 cubic kilometers of ice per year which is equivalent to 0 4 0 2 millimeters of global sea level rise per year most of this mass loss came from the west antarctic ice sheet

assessment of metal concentrations in lake sediments of southwest japan based on sediment quality guidelines geochemical analysis of the bottom sediments of lakes banryoko onbe hamahara and kijima in shimane prefecture of southwest japan was carried out to determine their metal concentrations and to assess the potential for ecological harm by comparison with sediment quality guidelines the work conducted includes water quality measurement and analyses of trace and major elements and rare earth element ree of sediments results showed that water quality of the lakes contrasts slightly between their upper and lower parts average abundances of as pb zn cu ni and cr in banryoko sediments were 27 33 90 27 25 and 46 ppm respectively compared to 31 52 175 44 44 and 75 ppm at onbe 11 26 96 13 13 and 35 ppm at hamahara and 24 43 193 31 12 and 30 ppm at kijima these concentrations exceeded the lowest effect level that has moderate impact on aquatic organisms as proposed by the new york state department of environmental conservation pb and cu abundances are comparable to the coastal ocean sediment database threshold while as and zn exceed this value indicating the concentrations of these metals are potentially toxic increases in the abundances of these metals in lake sediments are probably related to the reducing condition of the sediments anthropogenic sources and surface soil erosion the ree patterns of sediments in the study areas are broadly comparable to the average upper continental crust but show some contrast between lakes due to differing source litho type significant positive correlations between fe2o3 and as pb zn and cu were found in the sediments suggesting these metals may be adsorbed on fe oxides in the lake sediments

distribution of arsenic and other trace elements in the holocene sediments of the meghna river delta bangladesh geochemical study of the holocene sediments of the meghna river delta chandpur bangladesh was conducted to investigate the distribution of arsenic and related trace and major elements the work carried out includes analyses of core sediments and provenance study by rare earth element ree analysis results showed that the cores pass downward from silty clays and clays into fine to medium sands the uppermost 3 m of the core sediments are oxidized average oxidation reduction potential orp 230 mv and the orp values gradually become negative with depths 45 to 170 mv indicating anoxic conditions prevail in the meghna sediments the ree patterns of all lithotypes in the study areas are similar and are comparable to the average upper continental crust arsenic and other trace elements pb zn cu ni and cr have greater concentrations in the silts and clays compared to those in the sands positive correlation between as and fe was found in the sediments indicating as may be adsorbed on fe oxides in aquifer sediments

coordinated investigation of midlatitude upper mesospheric temperature inversion layers and the associated gravity wave forcing by na lidar and advanced mesospheric temperature mapper in logan utah mesospheric inversion layers mil are well studied in the literature but their relationship to the dynamic feature associated with the breaking of atmospheric waves in the mesosphere lower thermosphere mlt region are not well understood two strong mil events t 30 k were observed above 90 km during a 6 day full diurnal cycle na lidar campaign conducted from 6 august to 13 august logan utah 42 n 112 w colocated advanced mesospheric temperature mapper observations provided key information on concurrent gravity wave gw events and their characteristics during the nighttime observations the study found both mils were well correlated with the development and presence of an unstable region 2 km above the mil peak altitudes and a highly stable region below implicating the strengthening of mil is likely due to the increase of downward heat flux by the enhanced saturation of gravity wave when it propagates through a highly stable layer each mil event also exhibited distinct features one showed a downward progression most likely due to tidal gw interaction while the peak height of the other event remained constant during further investigation of atmospheric stability surrounding the mil structure lidar measurements indicate a sharp enhancement of the convective stability below the peak altitude of each mil we postulate that the sources of these stable layers were different one was potentially triggered by concurrent large tidal wave activity and the other during the passage of a strong mesospheric bore

relationship of topex poseidon altimetric height to steric height and circulation in the north pacific topex poseidon altimetric height is compared with 20 transpacific eddy resolving realizations of steric height the latter are calculated from temperature expendable bathythermograph xbt and salinity expendable conductivity and temperature profiler xctd profiles along a precisely repeating ship track over a period of 5 years the overall difference between steric height and altimetric height is 5 2 cm rms on long wavelengths 500 km containing 17 of the steric height variance the 3 0 cm rms difference and lowered coherence are due to the sparse distribution of altimeter ground tracks along the xbt section the 2 4 cm rms difference in the basin wide spatial mean appears to be due to fluctuations in bottom pressure differences between steric height and altimetric height increase near the western boundary but data variance increases even more and so the signal to noise ratio is highest in the western quarter of the transect basin wide integrals of surface geostrophic transport from steric height and altimetric height are in reasonable agreement the 1 9 104 m2 s 1 rms difference is mainly because the interpolated altimetric height lacks spatial resolution across the narrow western boundary current a linear regression is used to demonstrate the estimation of subsurface temperature from altimetric data errors diminish from 0 8 c at 200 m to 0 3 c at 400 m geostrophic volume transport 0 800 m shows agreement that is similar to surface transport with 4 8 sverdrup sv 106 m3 s 1 rms difference the combination of altimetric height with subsurface temperature and salinity profiling is a powerful tool for observing variability in circulation and transport of the upper ocean the continuing need for appropriate subsurface data for verification and for statistical estimation is emphasized this includes salinity measurements which significantly reduce errors in specific volume and steric height

combining altimeter and subsurface float data to estimate the time averaged circulation in the upper ocean 1 a new technique is presented for estimating time averaged upper ocean geostrophic velocity from a combination of altimeter data and subsurface float data the technique makes uses of the strong relationship between sea surface height anomaly and anomalous velocity at depth to reduce mesoscale eddy variability in subsurface float displacements the technique is demonstrated on a region in the north atlantic that was well sampled by argo floats the 2004 through 2006 time averaged density field was estimated from the surface to 2000 db by combining altimeter and hydrographic data from the floats in addition a reference velocity field was estimated at 1000 db based on a combination of altimeter data and subsurface float displacements the reference velocity field was combined with geostrophic shear based on the density field to produce a three dimensional estimate of geostrophic velocity from the surface to 2000 db the gulf stream transport in the upper 2000 db is estimated to be 76 sv at 73 w in addition an estimate of the 3 year average dynamic height at the surface was computed by combining the 1000 db reference dynamic height and the time averaged density field

rapid sea level rise abstract several global and regional factors contribute to observed sea level change along any particular coast global processes include changes in ocean mass glacio eustasy from ice melt ocean volume steric effects viscoelastic land movements glacioisostatic adjustment gia and changes in terrestrial water storage regional processes often connected to steric and glacial changes include changes in ocean circulation meridional overturning circulation moc glacial melting local gia regional subsidence and others paleoclimate instrumental and modeling studies show that combinations of these factors can cause relatively rapid rates of sea level rise exceeding 3 mm yr 1 over various timescales along particular coasts this paper discusses patterns and causes of sea level rise with emphasis on paleoclimatological records it then addresses the hypothesis of late holocene pre 20th century sea level stability in light of paleoclimatic evidence notably from reconstructions of sea surface temperature and glacial activity for significant climate and sea level variability during this time the practical difficulties of assessing regional sea level sl patterns at submillennial timescales will be discussed using an example from the eastern united states

correction to recent cooling of the upper ocean the recent cooling signal in the upper ocean reported by lyman et al 2006 is shown to be an artifact that was caused by a large cold bias discovered in a small fraction of argo floats as well as a smaller but more prevalent warm bias in expendable bathythermograph xbt data these biases are both substantially larger than sampling errors estimated in lyman et al 2006

sources of mesoscale variability of gravity waves part i topographic excitation abstract aircraft measurements of winds and temperatures collected during the gasp program are used to study the effects of topography as a source of mesoscale variability variances of fluctuations at the mesoscale over rough terrain are enhanced up to nearly two orders of magnitude compared to nonsource regions in some cases and are frequently enhanced by an order of magnitude the implications of these episodic enhancements of variances for the vertical transports of energy and momentum are considered in the framework of gravity wave theory the observed flight data are used to estimate the momentum flux u w on several flight segments results show that the flux is generally negative with mean value 0 26 m2 s 2 and with magnitudes ranging up to 1 5 m2 s 2 spectral analysis shows that the largest contributions to the net flux come from horizontal scales of 25 x 60 km finally the observed momentum fluxes are used to infer the anisotropy factor of gravity waves over rough terrain which is foun

large amplitude mountain waves in the mesosphere accompanying weak cross mountain flow during deepwave research flight rf22 mountain wave mw propagation and dynamics extending into the upper mesosphere accompanying weak forcing are examined using in situ and remote sensing measurements aboard the national science foundation national center for atmospheric research gulfstream v gv research aircraft and the german aerospace center falcon the measurements were obtained during falcon flights ff9 and ff10 and gv research flight rf22 of the deep propagating gravity wave experiment deepwave performed over mount cook new zealand on 12 and 13 july 2014 in situ measurements revealed both trapped lee waves having zonal wavelengths of x 12 km and less and larger scale vertically propagating mws primarily at x 20 60 km and 100 300 km extending from west to 400 km east of mount cook gv rayleigh lidar measurements from 25 to 60 km altitudes showed that the weak forcing and zonal winds that increased from 12 m s at 12 km to 40 and 130 m s at 30 and 55 km respectively enabled largely linear mw propagation and strong amplitude growth with altitude into the mesosphere

does strong tropospheric forcing cause large amplitude mesospheric gravity waves a deepwave case study the deepwave deep propagating wave experiment campaign was designed for an airborne and ground based exploration of gravity waves from their tropospheric sources up to their dissipation at high altitudes it was performed in and around new zealand from 24 may till 27 july 2014 being the first comprehensive field campaign of this kind a variety of airborne instruments was deployed onboard the research aircraft nsf ncar gulfstream v gv and the dlr falcon additionally ground based measurements were conducted at different sites across the southern island of new zealand including the dlr rayleigh lidar located at lauder 45 04 s 169 68 e we focus on the intensive observing period iop 10 on the 4 july 2014 when strong wsw winds of about 40 m s at 700 hpa provided intense forcing conditions for mountain waves at tropopause level the horizontal wind exceeded 50 m s and favored the vertical propagation of gravity waves into the stratosphere the dlr rayleigh lidar measured temperature fluctuations with peak to peak amplitudes of about 20 k in the mesosphere 60 km to 80 km msl over a period of more than 10 hours two research flights were conducted by the dlr falcon falcon flight 04 and 05 during this period with straight transects mt aspiring 2a over new zealand s alps at three different flight levels around the tropopause approx 11 km msl these research flights were coordinated with the gv research flight 16 where the largest mountain wave amplitudes at flight level approx 13 km msl were measured during deepwave additionally a first analysis of falcon s in situ flight level data revealed amplitudes in the vertical wind larger than 4 m s at all altitudes in the vicinity of the highest peaks of the southern alps here we present a comprehensive picture of the gravity wave characteristics and propagation properties during this interesting gravity wave event we use the airborne observations combined with a comprehensive set of ground based measurements consisting of 13 radiosoundings 1 5 hourly interval together with the dlr rayleigh lidar to cover the altitude range from the troposphere to the mesosphere high resolution 1 hourly ecmwf analyses and forecasts are used to estimate the propagation conditions of the excited mountain waves the goal of our investigation is to find out whether the large amplitude mesospheric gravity waves are caused by the strong tropospheric forcing

present environment of dam lake sambe southwestern japan a geochemical study of bottom sediments geochemical analyses of lakebed and core sediments from lake sambe on the outskirts of oda city in shimane prefecture in southwestern japan were carried out in order to assess the water quality and the concentration and distribution patterns of sixteen elements the lake water showed a stratified condition with respect to dissolved o2 and as fe and mn concentrations in the bottom layers which increased in the summer the chemical composition of the sediments as measured by x ray fluorescence included major and trace elements p ca sc ti v cr fe ni cu zn as sr zr pb and th and total sulfur ts elevated values of as zn v fe p and ts were present in several layers of the upper cores from 0 to 5 cm and other surface sediments increases in the abundances of these metals in lake sediments are probably related to the reducing condition of the sediments fine grained organic rich sediments and post depositional diagenetic remobilization moreover correlations between the concentrations of trace metals and iron in the sediments suggest their adsorption onto fe oxy hydroxides whereas correlations with sulfur indicate that they were precipitated as fe sulfides the average abundances of as pb zn and cu exceeded the lowest effect level and interim sediment quality guideline values that the new york state department of environmental conservation and the canadian council of ministers of the environment determined to have moderate impact on aquatic organisms in addition concentrations of as and zn exceeded the coastal ocean sediment database threshold value indicating potentially toxic levels therefore the presence of trace metals in the lake sediments may result in adverse effects on biota health

rayleigh lidar observations of a mesospheric inversion layer during night and day a narrow field of view rayleigh lidar has been constructed at millstone hill mit haystack observatory 42 6 n 71 5 w for observations of middle atmospheric temperatures throughout the diurnal cycle during a 31 5 h measurement on 19 21 march 2001 a mesospheric thermal inversion layer was observed in both the night and day it developed near 60 km in altitude progressed downward at 0 40 0 06 km h and had an overlying adiabatic lapse rate the inversion amplitude correlated with the evolution of stratospheric gravity wave activity although the mesospheric perturbations were too large to be due to conservative gravity wave growth alone the 24 h mean temperature profile shows no evidence of a residual inversion layer

southern argentina agile meteor radar initial assessment of gravity wave momentum fluxes 1 the southern argentina agile meteor radar saamer was installed on tierra del fuego 53 8 s in may 2008 and has been operational since that time this paper describes tests of the saamer ability to measure gravity wave momentum fluxes and applications of this capability during different seasons test results for specified mean tidal and gravity wavefields including tidal amplitudes and gravity wave momentum fluxes varying strongly with altitude and or time suggest that the distribution of meteors throughout the diurnal cycle and averaged over a month allows characterization of both monthly mean profiles and diurnal variations of the gravity wave momentum fluxes applications of the same methods for real data suggest confidence in the monthly mean profiles and the composite day diurnal variations of gravity wave momentum fluxes at altitudes where meteor counts are sufficient to yield good statistical fits to the data monthly mean zonal winds and gravity wave momentum fluxes exhibit anticorrelations consistent with those seen at other midlatitude and high latitude radars during austral spring and summer when no strong local gravity wave sources are apparent when stratospheric variances are significantly enhanced over the drake passage hot spot during austral winter however mlt winds and momentum fluxes over saamer exhibit very different correlations that suggest that mlt dynamics are strongly influenced by strong local gravity wave sources within this hot spot saamer measurements of mean zonal and meridional winds at these times and their differences from measurements at a conjugate site provide further support for the unusual momentum flux measurements

upper ocean heat content in the nordic seas 1 seven years of temperature profiles are obtained from the argo float project and are used to study the vertically integrated heat content for the nordic seas which is broken up into the norwegian basin greenland sea lofoten region and iceland plateau the world ocean atlas 2005 woa05 is used as the climatological baseline for temperature and hence heat content temporally and spatially averaged temperature profiles within the norwegian and iceland basins show good agreement between the argo and woa05 data sets for the greenland and lofoten basins the woa05 data show cooler surface temperatures by 1 2 c but still lie within 1 standard deviation of each other over the 7 year period the argo float data show circulation within each of the basins that is counterclockwise and some of the floats eventually disperse toward the outer edges of the basins vertically integrated heat content from 0 to 1200 m shows similar characteristics as the woa05 results including the timing and strength of the seasonal variability the anomalous heat content for the greenland and norwegian sea basins is calculated in depth bins of 400 m the greenland sea shows a warming trend over the 7 years of study which corresponds to a temperature increase of 4 1 0 3 10 2 c yr the norwegian sea basin shows interannual variability in heat content for the surface layer 0 400 m that may be related to the north atlantic oscillation nao during an nao phase the norwegian basin shows a warm phase and during an nao phase the norwegian basin is in a cold phase the correlation is small r 0 32 but different from zero correlation only at the 90 level implying that the variability in the ahc may be due to 1 local atmospheric forcing and hence changes in heat loss 2 atmospheric pressure differences that are not resolved by the nao index and 3 exchange of heat with the basin boundaries

evidence for a wind driven intensification of the kuroshio current extension from the 1970s to the 1980s the spatial and temporal characteristics of oceanic thermal variations in the mixed layer and main thermocline of the midlatitude north pacific are distinctive suggesting different physical origins within the main thermocline 400 m depth the variability is dominated by a westward intensified pattern of decadal scale indicative of enhanced eastward geostrophic flow along the southern flank of the kuroshio current extension during the 1980s relative to the 1970s the authors argue that the decadal scale change in the strength of the kuroshio extension was a result of the dynamical adjustment of the oceanic circulation to a decadal variation in wind stress curl according to sverdrup theory four times daily wind stress fields from the national center for atmospheric research national centers for environmental prediction reanalysis project are used to compute the decadal change in sverdrup transport associated with the 1976 77 climate transition it is shown that the decadal changes in sverdrup transport inferred from the wind stress curl field and in observed geostrophic flow inferred from the upper ocean thermal field are consistent both in terms of spatial pattern and magnitude the decadal change in depth averaged geostrophic transport along the kuroshio extension referenced to 1 km is 11 6 sv similar to the sverdrup transport change 11 5 13 9 sv the decadal scale thermocline variation along the western boundary between 308 and 408n exhibits a lag of approximately 4 5 yr relative to the decadal variation in the basin wide wind stress curl pattern this delay may be indicative of the transient adjustment of the gyre scale circulation to a change in wind stress curl via long baroclinic rossby waves

high altitude 0 100 km global atmospheric reanalysis system description and application to the 2014 austral winter of the deep propagating gravity wave experiment deepwave abstracta data assimilation system das is described for global atmospheric reanalysis from 0 to 100 km altitude we apply it to the 2014 austral winter of the deep propagating gravity wave exper

mean winds and momentum fluxes over jicamarca peru during june and august 1987 abstract data from the mesosphere stratosphere troposphere mst radar at jicamarca peru together with other available data are used to diagnose the mean structure of winds and gravity wave momentum fluxes from the surface to 90 km during two ten day campaigns in june and august of 1987 in the stratosphere a layer of maximum eastward flow associated with the quasi biennial oscillation qbo was seen to strengthen and descend rapidly from june to august overlying persistent westward flow a layer of enhanced signal return suggestive of a turbulent layer was observed just above the descending qbo eastward maximum notable zonal asymmetries were present during this transition and the local meridional circulation departed from zonal mean qbo theory a substantial northeastward momentum flux was found below 25 km which may be related to topographic gravity waves excited by southeastward flow across the andes in the lower mesosphere a relatively weak second mesopause semiannual oscillation is confirm

diatoms as indicators of sedimentary processes in burrinjuck reservoir new south wales australia abstract a combination of high and low resolution diatom analysis conducted on a transect of five sediment cores from the downstream section of burrinjuck reservoir southern new south wales australia has revealed that despite complex sedimentation patterns there are precise correlations between diatom stratigraphies spatially dependent variation in diatom sedimentation exists particularly that resulting from density current deposition however sediments deposited in this manner are readily identified from the diatom records the nature of diatom species assemblages and their variability aid in the identification of sediment provenance and the temporal resolution of individual samples respectively the results of this study which provide a complement to other research on the reservoir should in particular allow for more accurate reconstructions of the history of nutrient concentrations in and sediment yield to the reservoir

decadal spinup of the south pacific subtropical gyre abstract an increase in the circulation of the south pacific ocean subtropical gyre extending from the sea surface to middepth is observed over 12 years datasets used to quantify the decadal gyre spinup include satellite altimetric height the world ocean circulation experiment woce hydrographic and float survey of the south pacific a repeated hydrographic transect along 170 w and profiling float data from the global argo array the signal in sea surface height is a 12 cm increase between 1993 and 2004 on large spatial scale centered at about 40 s 170 w the subsurface datasets show that this signal is predominantly due to density variations in the water column that is to deepening of isopycnal surfaces extending to depths of at least 1800 m the maximum increase in dynamic height is collocated with the deep center of the subtropical gyre and the signal represents an increase in the total counterclockwise geostrophic circulation of the gyre by at least 20 at 1000 m a comparison of woce and

secondary gravity waves generated by breaking mountain waves over europe a strong mountain wave observed over central europe on 12 january 2016 is simulated in 2d under two fixed background wind conditions representing opposite tidal phases the aim of the simulation is to investigate the breaking of the mountain wave and subsequent generation of nonprimary waves in the upper atmosphere the model results show that the mountain wave first breaks as it approaches a mesospheric critical level creating turbulence on horizontal scales of 8 30 km these turbulence scales couple directly to horizontal secondary waves scales but those scales are prevented from reaching the hermosphere by the tidal winds which act like a filter initial secondary waves that can reach the thermosphere range from 60 to 120 km in horizontal scale and are influenced by the scales of the horizontal and vertical forcing associated with wave breaking at mountain wave zonal phase width and horizontal wavelength scales large scale nonprimary waves dominate over the whole duration of the simulation with horizontal scales of 107 300 km and periods of 11 22 minutes the thermosphere winds heavily influence the time averaged spatial distribution of wave forcing in the thermosphere which peaks at 150 km altitude and occurs both westward and eastward of the source in the 2 ut background simulation and primarily eastward of the source in the 7 ut background simulation the forcing amplitude is 2 that of the primary mountain wave breaking and dissipation this suggests that nonprimary waves play a significant role in gravity waves dynamics and improved understanding of the thermospheric winds is crucial to understanding their forcing distribution

heavy metals in sediments as evidence for recent pollution and quasi estuarine processes an example from lake druzno poland this article presents the results of a geochemical investigation of sediments from lake druzno northern poland a reservoir fed by freshwater from the catchment with periodic input of brackish water from vistula lagoon this study analyzed the spatial variation in heavy metal content in surface sediments as well as the temporal changes in metal content in two sediment cores dated using the 210pb method in the surface sediments the highest metal concentrations were recorded in the northern part of the lake with lower concentrations in the central and southern parts absolute values of metal concentrations in the cores were low but normalization with respect to al showed an increase during the second half of the 20th century mean enrichment factors ef in sediments from the second half of the 20th century ranged from insignificant 1 1 2 for fe to 1 55 3 3 for cu cd pb and zn the sediments deposited before 1950 had lower ef values 1 5 and had low variability results from both the surface sediments and the cores indicate that the main source of lake pollution is brackish water intrusion from the vistula lagoon via the contaminated river elbl g

on the origin of mesospheric bores abstract a dramatic front of airglow radiance and wave structure reported by taylor et al 1995 was attributed in a previous paper of ours dewan and picard 1998 to a manifestation of an internal undular bore in the mesosphere in the current paper we address the question of what physical process could be responsible for generating such a bore at that altitude while it is relatively easy to find sources of internal tropospheric bores including the dramatic morning glory the same cannot be said for mesospheric bores it will be argued here that a likely candidate for the generator of such bores is the interaction of gravity waves with the mean flow at a critical layer this interaction could take place within an already existing inversion layer the latter playing the role of the channel in which the bore propagates as huang et al 1998 have shown a similar wave critical level interaction may be responsible for the inversion layer in question hence we are proposing that the physical process producing the channel is the same as the one responsible for subsequently generating the bore

ocean gyre circulation changes associated with the north atlantic oscillation abstract observational evidence is presented for interannual to interdecadal variability in the intensity of the north atlantic gyre circulation related to the atmospheric north atlantic oscillation nao patterns a two point baroclinic pressure difference between the subtropical and subpolar gyre centers an oceanic analogue to the much used sea level pressure slp based atmospheric nao indices is constructed from time series of potential energy anomaly pea derived from hydrographic measurements in the labrador basin and at station s near bermuda representing the upper 2000 db eastward baroclinic mass transport between the two centers the transport index indicates a gulf stream and north atlantic current that gradually weakened during the low nao period of the 1960s and then intensified in the subsequent 25 years of persistently high nao to a record peak in the 1990s the peak to peak amplitude difference was 15 20 megatons per second mt s 1 with a 43 yr mean of about 60 mt s 1 a change of 25 33

drake antarctic agile meteor radar first results configuration and comparison of mean and tidal wind and gravity wave momentum flux measurements with southern argentina agile meteor radar 1 a new generation meteor radar was installed at the brazilian antarctic comandante ferraz base 62 1 s in march 2010 this paper describes the motivations for the radar location its measurement capabilities and comparisons of measured mean winds tides and gravity wave momentum fluxes from april to june of 2010 and 2011 with those by a similar radar on tierra del fuego 53 8 s motivations for the radars include the hotspot of small scale gravity wave activity extending from the troposphere into the mesosphere and lower thermosphere mlt centered over the drake passage the maximum of the semidiurnal tide at these latitudes and the lack of other mlt wind measurements in this latitude band mean winds are seen to be strongly modulated at planetary wave and longer periods and to exhibit strong coherence over the two radars at shorter time scales as well as systematic seasonal variations the semidiurnal tide contributes most to the large scale winds over both radars with maximum tidal amplitudes during may and maxima at the highest altitudes varying from 20 to 70 ms 1 in contrast the diurnal tide and various planetary waves achieve maximum winds of 10 to 20 ms 1 monthly mean gravity wave momentum fluxes appear to reflect the occurrence of significant sources at lower altitudes with relatively small zonal fluxes over both radars but with significant and opposite meridional momentum fluxes below 85 km these suggest gravity waves propagating away from the drake passage at both sites and may indicate an important source region accounting in part for this hotspot

rayleigh lidar observations of mesospheric inversion layers at poker flat alaska 65 n 147 w rayleigh lidar measurements of the stratosphere and mesosphere have been made on an ongoing basis over a three year period at poker flat alaska 65 n 147 w these observations have yielded 27 nightly measurements of the middle atmosphere temperature profile 40 80 km these nighttime measurements are distributed between august and april mesospheric inversion layers have been observed on five occasions the average altitude of the inversion layer peak is 60 km with average amplitude of 18 k the temperature gradients on the topside of the inversion layers approach the adiabatic lapse rate the inversion layers do not exhibit the apparent downward phase velocities that are commonly observed at lower latitudes furthermore the inversion layers appear significantly less frequently than at lower latitudes the observations are discussed in terms of current models and observations at other sites

mesoscale disturbances in the tropical stratosphere excited by convection observations and effects on the stratospheric momentum budget abstract the importance of the momentum flux of topographically generated mesoscale gravity waves to the extratropical middle atmosphere circulation has been well established for over a decade estimates of the zonal forcing due to tropical mesoscale gravity waves however are hampered by lack of data on their primarily convective sources the advent of aircraft measurements over tropical convective systems now makes such estimates possible without the use of ad hoc assumptions about amplitudes and phase speeds aircraft measurements from nasa s 1980 panama and 1987 step australia missions show that convectively generated disturbances observed just above the tropopause have horizontal scales comparable to those of the underlying anvils about 50 100 km with peak to peak isentropic surface variations of about 300 400 m satellite imagery of tropical anvil evolution indicates a typical lifetime of about five hours assuming that each convective system s impact on the stratosphere can be modeled as a time

dynamics of orographic gravity waves observed in the mesosphere over the auckland islands during the deep propagating gravity wave experiment deepwave abstracton 14 july 2014 during the deep propagating gravity wave experiment deepwave aircraft remote sensing instruments detected large amplitude gravity wave oscillations within mesospheric airglow and sodium layers at altitudes z 78 83 km downstream of the auckland islands located 1000 km south of christchurch new zealand a high altitude reanalysis and a three dimensional fourier gravity wave model are used to investigate the dynamics of this event at 0700 utc when the first observations were made surface flow across the islands terrain generated linear three dimensional wave fields that propagated rapidly to z 78 km where intense breaking occurred in a narrow layer beneath a zero wind region at z 83 km in the following hours the altitude of weak winds descended under the influence of a large amplitude migrating semidiurnal tide leading to intense breaking of these wave fields in subsequent observations starting at 1000 utc the linear fourier model constrained by upstream reanalysis

momentum budget of the migrating diurnal tide in the mesosphere and lower thermosphere 1 the leading terms of the momentum budget of the migrating diurnal tide are diagnosed from temperatures and geopotential height provided by thermosphere ionosphere mesosphere energetics and dynamics timed sounding of the atmosphere using broadband emission radiometry saber and the horizontal wind vector provided by timed doppler interferometer tidi the wave drag upon the tide is inferred as a residual of the classical and linear advective terms in the zonal and meridional momentum equations between 85 and 100 km the migrating diurnal tide is generally far from the classical description of chapman and lindzen 1970 the leading nonclassical terms are the meridional advection of zonally averaged momentum and wave drag effects encapsulated in the momentum residuals the magnitudes of the momentum residuals range between 50 and 150 m s 1 d 1 for the zonal component and 100 250 m s 1 d 1 for the meridional component the zonal momentum residual is generally in quadrature with the zonal wind tide while the meridional momentum residual is in antiphase with the meridional wind above 95 km winds and temperatures exhibit maximum amplitudes during the vernal equinox season but only a minor reduction in wave damping is observed our results suggest that rayleigh damping is inadequate to describe the relationship between the tide and the forces acting upon it

sediment type distribution in reservoirs sediment source versus morphometry bottom sediments were collected from seven texas reservoirs to assess the spatial distribution of sediment types in reservoirs the sediment samples were analyzed for water content organic content and grain size distributions the reservoirs are characterized by distinct water content patterns referred to in this paper as types i ii and iii that reflect the lithologic units comprising their drainage area the water content organic content and percent mud decreases from type i shale marl through type ii limestone marl sandstone to type iii granite gneiss schist sandstone reservoirs reported elemental concentrations in the reservoir sediments are consistent with concentrations in the dominant rocks within their drainage area while water depth accounts for part of the spatial distribution sediment source explains the overall distribution of sediment types coarse grained source rocks multiple source rocks and multiple tributaries which input sediment at different points contribute to an inconsistent sediment type distribution depending on the sediment source sand and gravel size sediments are present in the deeper regions of some reservoirs this disrupts the classical morphometry water depth slope controlled sediment distribution pattern coarser sediments in shallower regions and finer sediments in deeper regions of natural lakes thus the location of tributaries and the type of sediments they carry are the dominant factors that control the sediment type distribution in reservoirs

atmospheric conditions during the deep propagating gravity wave experiment deepwave abstractthis paper describes the results of a comprehensive analysis of the atmospheric conditions during the deep propagating gravity wave experiment deepwave campaign in austral winter 2014 different datasets and diagnostics are combined to characterize the background atmosphere from the troposphere to the upper mesosphere how weather regimes and the atmospheric state compare to climatological conditions is reported upon and how they relate to the airborne and ground based gravity wave observations is also explored key results of this study are the dominance of tropospheric blocking situations and low level southwesterly flows over new zealand during june august 2014 a varying tropopause inversion layer was found to be connected to varying vertical energy fluxes and is therefore an important feature with respect to wave reflection the subtropical jet was frequently diverted south from its climatological position at 30 s and was most often involved in strong forcing events of mountain waves at t

model measurement comparison of mesospheric temperature inversions and a simple theory for their occurrence 1 mesospheric temperature inversions are well established observed phenomena yet their properties remain the subject of ongoing research comparisons between rayleigh scatter lidar temperature measurements obtained by the university of western ontario s purple crow lidar 42 9 n 81 4 w and the canadian middle atmosphere model are used to quantify the statistics of inversions in both model and measurements inversions occur most frequently in the winter and exhibit an average amplitude of 10 k the model exhibits virtually no inversions in the summer while the measurements show a strongly reduced frequency of occurrence with an amplitude about half that in the winter a simple theory of mesospheric inversions based on wave saturation is developed with no adjustable parameters it predicts that the environmental lapse rate must be less than half the adiabatic lapse rate for an inversion to form and it predicts the ratio of the inversion amplitude and thickness as a function of environmental lapse rate comparison of this prediction to the actual amplitude thickness ratio using the lidar measurements shows good agreement between theory and measurements