high salinity intermediate water of the japan sea in the eastern japan basin conductivity temperature depth data from the midwinter in 1997 are examined for the presence of the intermediate water in the eastern japan basin in the northern part of the japan sea three different water masses can be detected with salinity extrema at intermediate depths between the main pycnocline and the upper portion of the japan sea proper water ujspw the shallower salinity maximum and the middle salinity minimum can be identified as the tsushima warm current water twcw and japan sea intermediate water respectively the deeper salinity maximum water with high temperature and high dissolved oxygen is identified as high salinity intermediate water hsiw and has density similar to ujspw 27 30 27 33 isopycnal analyses indicate that hsiw flows southeastward from the siberian coast where twcw outcrops and has an opportunity to become denser by direct cooling we conclude that twcw is the origin of hsiw which in turn is a source for ujspw

aspiration and outflow of the intermediate water in the east japan sea through the tsugaru strait 1 outflow of the intermediate water in the east japan sea through the tsugaru strait is inferred from the fact that profiling floats deployed below the sill depth in the central east japan sea moved out to the northwest pacific ocean through the strait careful analysis of the float trajectories reveals that profiling floats parked at 350m 700m and 800m could be uplifted from depths below the sill of the tsugaru strait and moved over the 140m deep sill with a probability close to 100 application of an analytical model for the bernoulli suction shows that intermediate waters can be aspirated over the sill depth of the tsugaru strait in late winter citation park j j k kim and j y yang 2008 aspiration and outflow of the intermediate water in the east japan sea through the tsugaru strait geophys res lett 35 l07601 doi 10 1029 2007gl032981

atlas of japan east sea hydrographic properties in summer 1999 abstract hydrographic properties from ctd and discrete bottle sample profiles covering the japan east sea in summer 1999 are presented in vertical sections maps at standard depths maps on isopycnal surfaces and as property property distributions this data set covers most of the sea with the exception of the western boundary region and northern tatar strait and includes nutrients ph alkalinity and chlorofluorocarbons as well as the usual temperature salinity and oxygen observations

a global morphology of gravity wave activity in the stratosphere revealed by the gps occultation data gps met using temperature profiles obtained by the gps met gps meteorology experiment from april 1995 to february 1997 we have extracted mesoscale temperature perturbations with vertical wavelengths ranging from 2 to 10 km and background brunt vaisala frequency squared n2 for each occultation event we can evaluate a potential energy ep which is assumed to be caused by atmospheric gravity waves the monthly mean values of ep at 15 20 km around japan showed an annual variation with an enhancement in winter which is consistent with the climatological behavior of the kinetic energy of gravity waves observed with the mu middle and upper atmosphere radar 34 9 n 136 0 e from 1985 to 1989 we have then derived the global distribution of ep at 20 30 km during northern hemisphere winter from november to february our analysis shows that the largest ep values are generally centered around the equator between 25 n and 25 s with considerable longitude variations longitudinal variations of ep at 20 30 km in a latitude range of 30 60 n are also analyzed resulting in larger ep values over the continents than over the pacific ocean using gps met data without antispoofing latitudinal variations of ep are determined in 15 45 km although large ep values are concentrated near the equator at 20 30 km ep tends to become larger at midlatitudes at 30 40 km and higher altitude regions at midlatitudes ep is found to be larger in winter months in both hemispheres height variations of ep indicate a decrease at 25 30 km and a monotonic increase above 30 km

a statistical study of gravity waves in the polar regions based on operational radiosonde data gravity waves in the lower polar stratosphere are examined using operational radiosonde observations gathered from 33 stations over a period of 10 years both the potential and kinetic energies of the gravity waves vary annually and reach maxima in winter in the arctic and in spring in the antarctic in the antarctic spring a region of large gravity wave energy propagates downward following the movement of a zone of high static stability associated with southern hemispheric warming moreover the enhanced energy region and the high stability zone coincide in the horizontal plane and move gradually from 135 e 50 s to 45 w 70 s over the south pole the vertical and horizontal directions of wave propagation are examined using hodograph analysis in the vertical most gravity waves transfer energy upward in the arctic while the percentage of downward energy propagation is relatively high in winter and spring in the antarctic horizontally gravity waves propagate westward relative to the mean wind in the arctic while in the antarctic the dominant direction varies from station to station the correlation between gravity wave energy in the lower stratosphere and the mean wind is also examined in the arctic gravity wave energy is highly correlated with the surface wind though in the antarctic it correlates with the stratospheric wind these results suggest that gravity waves observed in the arctic are forced by topography whereas in antarctica some sources may exist in the stratosphere one such source candidate is likely to be the polar night jet

trapped waves in the edge region of stratospheric polar vortices 1 a global distribution and seasonal variability of short period 2 days disturbances in the lower and middle stratosphere are investigated using 6 hourly european centre for medium range weather forecasts reanalysis data over 15 years 1979 1993 two dimensional spectral analysis and a recently developed lagrangian mean diagnostic are used for the analysis it is shown that the short period disturbances are most active around the polar night jet in each winter hemisphere they have a wavelike structure in the longitudinal direction with typical zonal wavelengths of 1 700 2 000 km i e zonal wave number 10 12 and a latitudinally evanescent structure with a half width of about 1 500 km suggesting that they are waves trapped in the edge region of the polar vortex where the latitudinal gradient of isentropic potential vorticity is maximized the trapped waves have a nearly barotropic structure over a depth greater than 10 km because the polar vortex in the northern hemisphere is much deformed and not symmetric around the pole dynamical characteristics of the trapped waves in the southern hemisphere alone are investigated by applying a lag correlation analysis to the reanalysis data the characteristics of trapped waves are fairly dependent on the state of the polar vortex such as zonal wind speed and its vertical shear they have a significant westward intrinsic phase velocity from june through october when the polar vortex is most stable this indicates that the trapped waves during this period have their own dynamics contrary to the filaments being passively advected by the large scale flow

gravity wave generation around the polar vortex in the stratosphere revealed by 3 hourly radiosonde observations at syowa station intensive radiosonde observations were performed at syowa station 69 0 s 39 6 e over about 10 days in each of march june october and december 2002 to examine inertia gravity wave characteristics in the antarctic lower stratosphere based on the 3 hourly observation data two dimensional i e vertical wavenumber versus frequency spectra of wind fluctuations were examined utilizing a double fourier transform method clear signals of gravity waves whose phases propagate upward suggesting downward energy propagation are detected in june and october when the polar night jet pnj was present on the other hand downward phase propagation i e upward energy propagation components are dominant in all months there is a spectral peak around the inertial frequency in a wide range of vertical wavenumbers in december when the background wind was weak whereas large spectral densities are distributed over lower frequency regions in june and october these spectral characteristics are consistent with the results obtained using a gravity wave resolving global circulation model gcm by sato et al dynamical characteristics are examined separately for upward and downward propagating gravity waves in june using a hodograph analysis method as a result it is found that upward and downward propagating wave packets observed simultaneously in the same height regions have similar horizontal wavelengths and phase velocities this fact suggests that these gravity waves are generated from the same source with a similar mechanism when the wave packets were observed both the local rossby number and the residual in the nonlinear balance equation estimated using ncep ncar reanalysis data are large around the pnj situated slightly to the lower latitudes of syowa station therefore it is likely that the observed inertia gravity waves are generated by a spontaneous adjustment around the geostrophically unbalanced pnj and propagate toward syowa station the possibility of spontaneous gravity wave generation around the pnj is confirmed by comparison with the gcm simulation by sato et al

formation and circulation processes of intermediate water in the japan sea abstract the formation and circulation processes of intermediate water in the japan sea have been investigated by study of the subduction of mixed layer water to simulate realistic seasonal variations in the velocity and hydrographic structures a numerical model with a nudging method for potential temperature and salinity which reproduced the general features in the japan sea is used close investigation of the subduction process reveals two major formation areas a and b of intermediate water area a 41 43 n west of 135 e corresponds to the region reported by recent observations whereas area b 40 43 n east of 136 e has not been reported so far the mixed layer water subducted in area a is advected southwestward and eventually its upper portion above 200 m reaches the eastern part of the japan basin whereas the lower branch below 200 m reaches the tsushima basin this indicates that the east sea intermediate water originates from the mixed layer in area a and suggests that the east sea

general aspects of a t213l256 middle atmosphere general circulation model 1 a high resolution middle atmosphere general circulation model gcm developed for studying small scale atmospheric processes is presented and the general features of the model are discussed the gcm has t213 spectral horizontal resolution and 256 vertical levels extending from the surface to a height of 85 km with a uniform vertical spacing of 300 m gravity waves gws are spontaneously generated by convection topography instability and adjustment processes in the model and the gcm reproduces realistic general circulation in the extratropical stratosphere and mesosphere the oscillations similar to the stratopause semiannual oscillation and the quasi biennial oscillation qbo in the equatorial lower stratosphere are also spontaneously generated in the gcm although the period of the qbo like oscillation is short 15 months the relative roles of planetary waves large scale gws and small scale gws in maintenance of the meridional structures of the zonal wind jets in the middle atmosphere are evaluated by calculating eliassen palm diagnostics separately for each of these three groups of waves small scale gws are found to cause deceleration of the wintertime polar night jet and the summertime easterly jet in the mesosphere while extratropical planetary waves primarily cause deceleration of the polar night jet below a height of approximately 60 km the meridional distribution and propagation of small scale gws are shown to affect the shape of the upper part of mesospheric jets the phase structures of orographic gws over the south andes and gws emitted from the tropospheric jet stream are discussed as examples of realistic gws reproduced by the t213l256 gcm

preliminary seafloor subsidence values measured over the phalen mine 1 west panel sydney coalfield nova scotia abstract in 1987 and 1988 detailed marine hydrographic surveys were carried out over the phalen mine workings in the sydney coalfield nova scotia in order to establish the pre and post mining seafloor topographies after describing the equipment survey techniques and data processing methodology used the paper compares the 1987 and 1988 hydrographic data for four survey lines monitored pre and post mining and presents the preliminary seafloor subsidence values measured over the phalen i west longwall panel

energy enhancements of gravity waves in the antarctic lower stratosphere associated with variations in the polar vortex and tropospheric disturbances 1 gravity waves in the antarctic lower stratosphere are examined using original operational radiosonde data obtained at syowa station 69 0 s 39 6 e with fine vertical resolution in the lower stratosphere the temporal variation in gravity wave energy depends on height in the height region of 13 15 km just above the tropopause the seasonal variation in gravity wave energy is not evident the wave energy is rather enhanced when the absolute value of potential vorticity in the upper troposphere becomes small over syowa station this fact implies that tropospheric disturbances affect the dynamical processes of gravity waves there however the gravity wave energy in the height region of 15 25 km shows clear seasonal variation having a maximum in spring the time variation in gravity wave energy is examined in detail in terms of the polar vortex by using the equivalent latitude coordinate energy enhancements occur when the edge of the polar vortex approaches syowa station and the enhancements are especially large when the polar vortex breaks down in spring these results suggest that height variation in the background atmosphere leads to the difference of wave characteristics between the two height regions the enhancements of wave energy are partly explained as modification of the wave structure by the background wind speed and the static stability but it is also likely that enhancements of wave activity contribute to the energy enhancement at the edge of the polar vortex in spring

a new perspective on origin of the east sea intermediate water observations of argo floats abstract the east sea intermediate water esiw defined as the salinity minimum in the east sea hereafter es sea of japan is examined with respect to its overall characteristics and its low salinity origin using historical argo float data from 1999 to 2015 our findings suggest that the esiw is formed in the western japan basin 40 42 n 130 133 e especially west of the north korean front in north korean waters where strong negative surface wind stress curl resides in wintertime the core esiw near the formation site has temperatures of 3 4 c and less than 33 98 psu salinity warmer and fresher than that in the southern part of the es in order to trace the origin of the warmer and fresher water at the sea surface in winter we analyzed the data in three different ways 1 spatial distribution of surface water properties using monthly climatology from the argo float data 2 seasonal variation of heat and salt contents at the formation site and 3 backtracking of surface drifter trajectories based on these analyses it is likely that the warmer and fresher surface water properties found in the esiw formation site are attributed to the low salinity surface water advected from the southern part of the es in autumn

vertical structure of the upper ocean during the marine light mixed layers experiment the marine light mixed layers mlml experiments took place in the subarctic north atlantic ocean approximately 275 miles south of reykjavik iceland during 1989 and 1991 the 1991 field program took place from april 30 to september 6 and included a central surface mooring to document the temporal evolution of physical biological and optical properties in this paper we describe the physical variability observed at the 1991 mooring site concentrating on the vertical structure of temperature and velocity in the upper 300 m of the water column and their changes in response to heat and momentum fluxes at the sea surface the deployment period included the spring transition when upper ocean re stratification was initiated after deep winter mixing and the fall transition when mixed layer deepening began again the dominant signal in temperature was seasonal variation with a 6 c increase observed at the sea surface from may to august prior to development of the seasonal stratification a period dominated by near surface temperature variability was observed in association with a 15 day mean flux of only 20 w m 2 into the ocean pronounced day night oscillations of heat flux during this period resulted in alternating development and destruction of stratification and intense diurnal cycling of the mixed layer depth a qualitative comparison of the observed temperature structure to the prediction of a one dimensional mixed layer model showed that local processes dominated during the initiation of restratification and during most of the summer warming period nonlocal processes were important after the fall transition

gravity wave characteristics in the lower atmosphere at south pole a 4 year 1993 1996 temperature and wind data set obtained from over 2000 high resolution balloon soundings at south pole is used to study gravity wave characteristics in the troposphere and lower stratosphere extensive analyses of energy density spectra and static stability are performed to present a comprehensive view of the gravity wave characteristics in the lower atmosphere at south pole our results show that the gravity waves are ubiquitous and often fairly strong at south pole even though the generation mechanisms are not clear gravity wave characteristics are in general similar to those obtained at other high latitude southern hemisphere stations potential energies vary between about 0 5 j kg and 5 j kg with season and altitude variations in kinetic energies are not well correlated with potential energy variations and range from 1 j kg to 11 j kg we observe significant seasonal variations of the slope and magnitude of the vertical wavenumber spectrum of temperature fluctuations especially in the stratosphere in general the gravity waves in the stratosphere are stronger weaker in austral spring fall wave activity in the troposphere has little seasonal dependence stability analysis shows that instabilities are more likely to occur in the troposphere than in the stratosphere the probability of wave instability is 13 7 in the troposphere and 5 4 in the stratosphere this is due to the less stable stratification in the troposphere where the buoyancy period averages 8 3 min compared to 4 9 min in the stratosphere dynamic shear instability is more likely to occur than convective instability 11 versus 2 6 in the troposphere and 4 7 versus 0 7 in the stratosphere due to the prevailing strong wind shear the instability probabilities vary seasonally with the austral winter exhibiting the highest probability of instabilities dynamic and convective instabilities combined in both the troposphere and stratosphere

longitudinally dependent ozone increase in the antarctic polar vortex revealed by balloon and satellite observations the horizontal structure of processes causing increases in ozone in the antarctic polar vortex was examined using data measured in 2003 from an ozonesonde observation campaign at syowa station 39 68e 69 08s and from the improved limb atmospheric spectrometer ii ilas ii onboard the advanced earth observing satellite ii the ilas ii data are daily and distributed uniformly at 14 points in the zonal direction mostly at polar latitudes the antarctic ozone hole that developed in 2003 was one of the largest recorded the period of focus in this study is 26 september through 24 october when a strong polar vortex was situated in the stratosphere an ozone mixing ratio contour 1 0 ppmv moved downward near a height of 20 km during the period of focus this increase in ozone is likely to result from downward transport of ozone rich air originating from lower latitudes by brewer dobson circulation first the descent rate of the mixing ratio contour was estimated by taking the geometric height as the vertical coordinate for the deep vortex interior around 20 km a significant longitudinal dependence was observed an analysis using ecmwf operational data shows that this dependence can be approximately explained by longitudinally dependent vertical movements of the isentropes caused by a zonal wavenumber 1 quasi stationary planetary wave with amplitude and phases varying on a seasonal time scale next the descent rate was calculated around 500 k around 20 km by taking the potential temperature isentrope as the vertical coordinate the longitudinal dependence was still present using this coordinate meaning that the ozone mixing ratio and its increase are not constant on the isentropic layer even in the interior of the polar vortex a backward trajectory analysis showed that air parcels with large ozone mixing ratios were mostly transported from the polar vortex boundary region this result suggests that lateral transport mixing is important even before the breakup of the polar vortex results from a tracer tracer correlation analysis of o3 and long lived constituent n2o were also consistent with this inference the contribution of lateral mixing to the increase in ozone was estimated at about 17 6 4 that of the brewer dobson circulation around 20 km using the calculated descent rates the results of this study also imply that lagrangian downward motions in the vortex interior are not correctly estimated without accounting for lateral mixing even if the polar vortex is dynamically stable

modeling dense pyroclastic basal flows from collapsing columns 1 a two layer model for the formation of dense pyroclastic basal flows from dilute collapsing volcanic eruption columns is presented the collapsing dilute current is described by depth averaged isothermal continuum conservation equations the dense basal flow is modelled as a granular avalanche of constant density simulations demonstrate that pyroclastic flow formation and behavior is dependent upon slope conditions when the dilute part of the current has lost most of its mass the dilute current runout increases with decreasing particle size and increasing initial column height if the dilute current has transferred its mass to the dense basal flow on volcanic slopes with inclination angle greater than the friction angle of the basal flow then the basal flow will continue to propagate until frictional forces bring it to rest if the dilute current terminates on lower angled slopes frictional forces dominate the basal flow preventing further front propagation

wintertime temperature maximum at the subtropical stratopause in a t213l256 gcm 1 a wintertime temperature maximum can be observed at the subtropical stratopause but does not appear in the radiative equilibrium temperature distribution this structure was well simulated using a high resolution general circulation model and examined in detail the stratopause temperature is latitudinally maximized in the winter subtropics because of a strong downwelling of the meridional circulation from summer tropics to winter subtropics passing above the stratopause its strong meridional flow consists of two parts a strong poleward flow in the winter subtropics with nearly vertically aligned contours of absolute angular momentum m and a strong cross equatorial flow toward winter hemisphere above the tropical stratopause with nearly horizontally aligned m contours the strong poleward flow in the winter subtropics is driven by a large eliassen palm e p flux convergence in a small absolute vorticity region the large e p flux convergence is due to extratropical planetary waves and asymmetric inertial instability on the other hand the strong cross equatorial flow is induced along the m contour to satisfy mass continuity with the strong poleward flow in the winter subtropics and exists in the easterly phase of s sao with a small latitudinal gradient of m the easterly of s sao during its mature phase acts as a corridor for cross equatorial meridional circulation while cross equatorial meridional circulation contributes to driving the easterly of s sao in its development phase

spatial and temporal variability of the north korean cold water leading to the near bottom cold water intrusion in korea strait abstract in the deepest region of korea strait the surface temperature is highest in august lowest in march while the near bottom temperature is lowest in september highest in may cross spectral analysis of the monthly temperature data between the two layers shows high coherence at the annual frequency with phase of 154 why and how does such a nearly opposite phasing occur between the surface and the near bottom temperatures there this study aims at answering these questions using historical and recently observed data cold and relatively fresh subsurface water flowing southward along the east coast of korea and known as the north korean cold water nkcw becomes noticeable in april near the sokcho coast the zonal temperature gradient there is largest around june the width of the nkcw becomes larger from april to august after october the nkcw retreats back toward the coast the southward movement of the nkcw is thus strong over a period of six to seven months and weak in winter especially in february the nkcw flows southward relatively quickly along the coast in april to october and arrives at the ulleung basin within one to two months because of the sill between the ulleung basin and korea strait this water cannot continue to flow to south but piles up for about two to three months before it moves over the sill the convergence of the subsurface cold water in the ulleung basin displaces the isopycnals upward and this water then intrudes over the sill along the isopycnals this explains why in april or may when this water appears noticeably at the sokcho coast the near bottom water in korea strait is warmest and in august or september when the nkcw which is piled up enough at the southern end of the ulleung basin intrudes to korea strait the near bottom temperatures there are at their lowest the origin of the nkcw seems to be the water of salinity less han 34 1 psu and surface density of 27 or higher which sinks in the northwestern east sea in january march the sinking of the water results from surface cooling in winter and is intensified due to the strong negative windstress curl the cold and relatively fresh water formed in the northwestern east sea is hypothesized to flow to the ulleung basin along three major paths along the east coast of korea through the channel north of ulleung do island and through the channel between ulleung do and dok do islands

gravity waves appearing in a high resolution gcm simulation global characteristics of gravity waves in the lower stratosphere are examined using a gcm with high resolution in both the horizontal t106 corresponding to about 120 km and the vertical 600 m the bottom boundary condition of the model is that of an aquaplanet with perpetual february sea surface temperature the simulated gravity waves are in good agreement with mesosphere stratosphere troposphere mst radar observations at a middle latitude on the gravity wave structure and on the frequency spectra as a function of height the frequency spectra of simulated wind and temperature fluctuations are also examined as a function of latitude large values of spectral density are observed at frequencies higher than the inertial frequency f in a weak wind region around 20 km which is consistent with the characteristics of internal gravity waves an isolated peak is observed near f for horizontal wind spectra at latitudes higher than 108 while the energy is distributed in a wide range of frequency at lower latitudes where f approaches zero further analysis is performed of those fluctuations having periods shorter than 24 h and those having vertical wavelengths smaller than 5 km these are frequently analyzed as gravity waves using observation data the distribution of energy and momentum fluxes in the latitude height section is examined the result indicates that short period waves mostly propagate upward and poleward from the equatorial region the wave energy reaches about 508 lat at the 27 km altitude a negative positive maximum of vertical flux of meridional momentum y9w9 is seen above the subtropical jet in the northern southern hemisphere for small vertical scale gravity waves this is consistent with the preferred equatorward propagation of the wave indicated by a statistical analysis based on mst radar observations the ratio of potential to kinetic energy maximizes over the equator and decreases poleward the eliassen palm flux divergence associated with gravity waves is decelerative above the subtropical jet albeit small

doppler ducting of short period gravity waves by midlatitude tidal wind structure 1 multiwavelength airglow image data depicting a short period 4 9 min atmospheric gravity wave characterized by a sharp leading front have been analyzed together with synoptic meteor radar wind data recorded simultaneously from bear lake observatory utah 41 6 n 111 6 w the wind data suggest the presence of a semidiurnal tide with horizontal winds peaking at around 60 m s along the sse direction of motion 170 from north of this short period wave it was found that the gravity wave was most probably ducted because of the doppler shift imposed by this wind structure a marked 180 phase shift was observed between the near infrared oh and the oi 557 7 nm emissions numerical simulation results for similar ducted waves excited by idealized model sources suggest that the phase shift between the wave modulated airglow intensities may be explained simply by chemical processes rather than by wave dynamics phase velocities of simulated waves however appear higher than those of observed waves suggesting the importance of tidal thermal structure in determining the doppler ducted wave characteristics

a review of mining subsidence instrumentation and its potential application for seabed monitoring abstract extensive mineable coal reserves exist in the offshore portion of the sydney coalfield nova scotia the near surface portion of these reserves are particularly attractive in economic terms but their extraction is constrained by the amount of subsidence generated at the seafloor field proven undersea subsidence guidelines are therefore required to allow the optimal recovery of these reserves without producing unacceptable risks regarding major water inflows to the mine workings to monitor seafloor subsidence an instrumentation scheme is required that is rugged and capable of operating in the marine environment without maintenance for prolonged periods of time and during bad weather and ice conditions however to identify an optimum scheme it is first necessary to undertake a review and evaluation of existing subsidence monitoring systems that have been used on land and which may with suitable research and development and or modification be capable of use in marine conditions two principal techniques direct and indirect subsidence monitoring systems are reviewed and these include geodetics lasers geotechnical instrumentation and automatic data acquisition systems in addition potential geophysical methods for subsidence monitoring are described along with a review of the development expected with conventional land based and subsurface systems the paper concludes with a discussion of the potential application of these techniques for monitoring seafloor subsidence profiles

three dimensional structure of mass weighted isentropic time mean meridional circulations abstractthe present study develops a diagnostic framework for investigating the three dimensional 3 d structure of mass weighted isentropic time mean t mim meridional circulations and conducts a preliminary analysis of the winter hemispheres the t mim meridional velocity can unfold in the zonal direction time averaged two dimensional 2 d mass weighted isentropic zonal means furthermore the t mim velocity can be decomposed into the unweighted isentropic time mean utm velocity and the temporal eddy correlated transport velocity the so called bolus velocity the bolus velocity greatly contributes to the 2 d extratropical direct circulation in the troposphere and to the brewer dobson circulation in the stratosphere the 3 d bolus velocity seems to reflect the geographical distributions of baroclinic instability wave activity in the boreal winter both low level equatorward flows and upper level poleward flows are located around the north pacific and north atlantic storm tracks in the austral w

atmos atlas 3 observations of long lived tracers and descent in the antarctic vortex in november 1994 observations of the long lived tracers n2o ch4 and hf obtained by the atmospheric trace molecule spectroscopy atmos instrument in early november 1994 are used to estimate average descent rates during winter in the antarctic polar vortex of 0 5 to 1 5 km month in the lower stratosphere and 2 5 to 3 5 km month in the middle and upper stratosphere descent rates inferred from atmos tracer observations agree well with theoretical estimates obtained using radiative heating calculations air of mesospheric origin n2o 5 ppbv was observed at altitudes above about 25 km within the vortex strong horizontal gradients of tracer mixing ratios the presence of mesospheric air in the vortex in early spring and the variation with altitude of inferred descent rates indicate that the antarctic vortex is highly isolated from midlatitudes throughout the winter from approximately 20 km to the stratopause the 1994 antarctic vortex remained well isolated between 20 and 30 km through at least mid november

water masses and decadal variability in the east sea sea of japan abstract water masses in the east sea are newly defined based upon vertical structure and analysis of ctd data collected in 1993 1999 during circulation research of the east asian marginal seas creams a distinct salinity minimum layer was found at 1500 m for the first time in the east sea which divides the east sea central water escw above the minimum layer and the east sea deep water esdw below the minimum layer escw is characterized by a tight temperature salinity relationship in the temperature range of 0 6 0 12 c occupying 400 1500 m it is also high in dissolved oxygen which has been increasing since 1969 unlike the decrease in the esdw and east sea bottom water esbw in the eastern japan basin a new water with high salinity in the temperature range of 1 5 c was found in the upper layer and named the high salinity intermediate water hsiw the origin of the east sea intermediate water esiw whose characteristics were found near the korea strait in the southwestern part of the east sea in 1981 kim k chung j y 1984 on the salinity minimum and dissolved oxygen maximum layer in the east sea sea of japan in t ichiye ed ocean hydrodynamics of the japan and east china seas pp 55 65 amsterdam elsevier science publishers is traced by its low salinity and high dissolved oxygen in the western japan basin ctd data collected in winters of 1995 1999 confirmed that the hsiw and esiw are formed locally in the eastern and western japan basin creams ctd data reveal that overall structure and characteristics of water masses in the east sea are as complicated as those of the open oceans where minute variations of salinity in deep waters are carefully magnified to the limit of ctd resolution since the 1960s water mass characteristics in the east sea have changed as bottom water formation has stopped or slowed down and production of the escw has increased recently

decadal changes in meridional overturning circulation in the east sea sea of japan abstractmeridional overturning circulation moc is vital to distributing heat freshwater and dissolved matter in semi enclosed deep marginal seas such as the east sea es as our understanding

seasonal variation of the korea strait bottom cold water and its relation to the bottom current 1 analysis of high resolution hydrographic and current data revealed that the korea strait bottom cold water ksbcw flowed into the korea strait from may to january and contained two temperature minimums one in august september and another in december january with the main current flows confined within 70 km of the korean coast maximum southwestward bottom currents corresponded with the temperature minimums time series of bottom current and temperature near the korean coast clearly showed that the bottom temperature decreased as the bottom current strengthened seasonal variation of the ksbcw was linked to the combined effects of the barotropic and baroclinic current variations in the korea strait the annual minimum bottom temperature of the ksbcw was associated with the maximum southwestward baroclinic component the ksbcw had a secondary maximum southwestward bottom current and secondary minimum temperature in december january when the tsushima warm current twc flowing into the east japan sea ejs had the minimum volume transport

interannual variability of the vertical descent rate in the antarctic polar vortex to investigate a descent rate in the antarctic polar vortex we analyzed the long lived trace gas data derived from the halogen occultation experiment on board the upper atmosphere research satellite during the 6 year period from 1992 to 1997 by comparing the antarctic fall february and march and spring september and october methane profiles we estimated the middle stratospheric descent for each of the six winters large year to year variations are seen 1 2 1 8 km month 1 at 0 6 ppmv which consist of a biennial oscillation and a decreasing trend for the period analyzed the descent rate is larger in the even years 1992 1994 and 1996 than in the odd years 1993 1995 and 1997 dynamical fields for the 6 years are also analyzed using the united kingdom meteorological office assimilation data the differences between the even and odd years are clear in the midwinter in the even years the downward and poleward movement of the westerly jet occurs earlier the thermal wind relation infers that this event is associated with the development of a warm pool around the antarctic stratopause resulting from adiabatic heating due to the downward motion of air planetary wave activity over the winter season is more vigorous in the even years than in the odd years suggesting a close relationship between the mean flow and planetary waves

pre mining seafloor topography determination over the phalen mine workings sydney coalfield nova scotia abstract in 1987 a detailed marine geophysics survey consisting of precision echosounder and sub bottom profiling was undertaken to establish the pre mining seafloor topography over the phalen mine workings in the sydney coalfield nova scotia if the same survey lines and monitoring techniques are subsequently used to establish the post mining seafloor topography a comparison of the two data sets may allow an evaluation of the resultant seafloor subsidence profiles after a brief review of the progress of the longwall seafloor subsidence monitoring program the paper examines the marine survey undertaken to establish the pre mining seafloor topography in addition to outlining the instrumentation and survey techniques used the data processing methodology is described and the survey results discussed

wavelet analysis of stratospheric gravity wave packets over macquarie island 2 intermittency and mean flow accelerations we calculate the mean flow accelerations due to gravity wave packets observed in the lower stratosphere over macquarie island 55 s 159 e between february 1994 and april 1995 the parameters of the wave packets were extracted from twice daily radiosonde soundings using a wavelet based analysis method introduced by zink and vincent this issue the deduced wave parameters are used to directly compute momentum flux profiles in the lower stratosphere and the shortcomings of this approach to assess mean flow accelerations are discussed we then use the observed wave packets as an input spectrum in a linear ray tracing model the vertical extent of the detected wave packets allows us to define an expression for wave intermittency which enables us to compute zonal accelerations in the stratosphere and mesosphere in the stratosphere the waves produce an acceleration of the mean flow in accordance with predictions in the mesosphere the inferred wave drag is 2 3 times larger than previous observational and theoretical estimates

influence of tropical convection on the southern hemisphere ozone maximum during the winter to spring transition 1 during the southern hemisphere sh winter a zonally asymmetric maximum in column ozone develops south of australia which amplifies from august through october this ozone maximum lies in the band 50 60 s and extends from the southern indian ocean to the eastern pacific it is proposed that the location of the ozone maximum is due to the geographical distribution of outflow from tropical convection in the upper troposphere and lower stratosphere utls which is concentrated over the southern indian ocean this southward flow of tropical air creates subtropical anticyclones in the utls and provides the angular momentum for the entrance to the australian westerly jet the ozone rich troughs in synoptic waves breaking on the jet contribute to the monthly mean ozone maximum poleward of the jet as indonesian convection contracts zonally and shifts eastward during sh spring so do the australian jet and ozone maximum in addition extratropical planetary waves become more active from august through october convective outflow surges lead to amplification of subtropical anticyclones which often extend into the lower stratosphere and merge with stalling planetary wave ridges amplification of these ozone rich ridges over the high latitude south pacific contributes to the eastward shift of the ozone maximum the utls over the southern indian ocean appears to be a sensitive region where tropical convection can influence extratropical planetary waves via excitation of subtropical anticyclones and propagation of rossby wave activity through the connecting westerly waveguide

sea surface temperature fronts in the east japan sea and temporal variations 1 the spatial pattern of sea surface temperature sst fronts and its seasonality are presented for the entire east japan sea they are based on semi monthly sea surface temperature sst gradient maps constructed from declouded sst images over the period 1990 1995 fronts in the east sea can be assigned to the subpolar front spf in its central sea areas and to other fronts along the continental shelves it is observed for the first time that the spf located mostly along about 40 n between 132 3 e and 138 e bifurcates at both its eastern and western ends the spatial structure of the spf shows strong seasonality associated with temporal variations of a warm eddy off the east coast of korea surface cooling due to siberian cold air south of vladivostok and bifurcation of the tsushima warm current west of the tsugaru strait we have also observed an isolated frontal zone trapped by a seamount in the northeastern part of the japan basin

deep currents obtained from argo float trajectories in the japan east sea abstract the deep currents at 700 800 m depths from argo float trajectories including pre argo floats have been compiled from 1999 to 2010 in the japan east sea jes more than 14 000 velocities from the dataset provides the first view of interbasin scale dependency in deep currents of the jes such as mean circulation and eddy variability especially with an emphasis on their topographic steering characteristics the observational findings in this study are 1 the argo observation exhibits dominance of cyclonic mean circulation in the entire jes yet with a distinct interbasin variability of its magnitude the mean circulation is strongest in the eastern japan basin jb while overall currents in the ulleung basin ub are weaker than that in the eastern japan basin and western yamato basin yb by a factor of two to three 2 the eddy kinetic energy eke is maximum in the western japan basin where strong dipole structure of wind stress curl in winter is located the interior of each basin the eastern jb ub and yb has local maxima of the eke a factor of four to five smaller than that in the western jb 3 cyclonic bottom following characteristics prevail in the bin averaged velocities however the individual deep flows presumably containing temporal variability have a preference to follow topography not only with cyclonic flows shallow depth to the right but also anticyclonic flows shallow depth to the left especially when flows are highly energetic occurrence of anticyclonic flows is proportional to the local eke level relative to mean kinetic energy implying that such flows could exist only in a transient manner such as topographic rossby waves the argo observations may demonstrate an asymmetry of stable cyclonic and unstable anticyclonic circulation in the marginal seas of the northern hemisphere as the previous theoretical modeling studies suggested

a review and evaluation of empirical and analytical subsidence prediction techniques abstract a review and evaluation of empirical and analytical subsidence prediction techniques were undertaken as part of a long term research program into seafloor subsidence in the sydney coalfield nova scotia empirical methods reviewed include the national coal board type curves profile and influence functions incremental design and stochastic methods analytical methods reviewed include closed form elastic solutions finite difference finite element boundary integral and a mechanistic model after an initial review of the empirical and analytical methods as well as the available computer programs for subsidence prediction a comparison is made between the results obtained from six specific prediction methods applied to a hypothetical case history typical of the sydney coalfield

evolution and formation of north atlantic eighteen degree water in the sargasso sea from moored data abstract two profiling subsurface moorings were deployed as part of the clivar mode water dynamics experiment climode to study the formation and evolution of eighteen degree water edw from november 2006 to november 2007 both moorings were deployed south of the gulf stream in the edw outcrop region the northwestern part of the subtropical gyre of the north atlantic the two moorings captured the seasonal evolution of edw characterized by gradual mixed layer deepening and wintertime outcrop rapid restratification from may to june and slower dissipation during the rest of the year superimposed on this seasonal cycle the moored records are characterized by high frequency passing of eddies with a characteristic time scale of 10 days i e it took about 10 days for eddies to pass the mooring sites the net impact of these eddy fluxes is evaluated by analyzing one dimensional heat and salt budgets of the upper ocean at the moorings and comparing them to the local air sea fluxes it is shown that oceanic lateral fluxes converge heat and salt into the formation region during winter thus offsetting the heat loss to the atmosphere and influencing the formation of edw a comparison with results from a one dimensional model shows that without the lateral fluxes edw would outcrop earlier and it would be colder and fresher the warm salty waters transported into the region originate from the gulf stream and this suggests that frontal processes likely play a fundamental role in edw formation and its evolution

three dimensional structure of the wind driven circulation in the subtropical north pacific abstract the subduction rate is calculated for the north pacific based on levitus climatology data and hellerman and rosenstein wind stress data because the period of effective subduction is rather short subduction rates calculated in eulerian and lagrangian coordinates are very close the subduction rate defined in the lagrangian sense consists of two parts the first part is due to the vertical pumping along the one year trajectory and the second part is due to the difference in the winter mixed layer depth over the one year trajectory since the mixed layer is relatively shallow in the north pacific the vertical pumping term is very close to the ekman pumping while the sloping mixed layer base enhances subduction especially near the kuroshio extension for most of the subtropical north pacific the subduction rate is no more than 75 m yr 1 slightly larger than the ekman pumping the water mass volume and total amount of ventilation integrated for each interval of 0 2 unit is computed the corre

time variations of descent in the antarctic vortex during the early winter of 1997 1 we analyzed long lived chemical constituents observed by the improved limb atmospheric spectrometer ilas on board the advanced earth observing satellite adeos to study the stratospheric descent in the southern hemisphere polar vortex the ilas n2o distribution inside the polar vortex exhibited clear downward motion in february to june 1997 average descent for the 5 months is estimated to be 2 1 1 7 km month 1 in the middle stratosphere in late april to june when planetary waves are relatively active the vertical velocity displays time variations with a period of about 10 days these time variations also synchronize with both time variations of the temperature time change t and the eliassen palm flux divergence df in high latitudes moreover a correlation coefficient map in the latitude height cross section between the vertical velocity and the temperature time change reveals an interesting four box pattern suggesting warming below 10 hpa and cooling above 10 hpa in the polar region 70 90 s and an opposite distribution in midlatitudes 40 70 s when large descent is observed inside the polar vortex it is just like the meridional circulation in response to df induced by planetary waves which was first illustrated by matsuno s stratospheric sudden warming theory

abrupt changes in meteorological conditions observed at an inland antarctic station in association with wintertime blocking time evolution of a prominent wintertime blocking event over east antarctica and the associated drastic changes in weather conditions observed at an inland station are documented a strong blocking ridge was formed at the leading edge of a quasi stationary rossby wavetrain where a wave activity flux emanating from the subtropics was convergent the ridge pumped up heat and moisture from lower latitudes into inland antarctica with a strong poleward flow along its upstream flank the station was situated under this flow just for two days during which the normal condition with cold and clear weather was markedly disturbed the flow climbing up the continental slope led to cloud formation above the inland station enhanced downward longwave radiation from the clouds and enhanced vertical mixing associated with the record setting wind speeds resulted in a sudden drastic increase in surface air temperature and the breakdown of the developed surface inversion layer

computations of diabatic descent in the stratospheric polar vortex a radiation model together with national meteorological center temperature observations was used to compute daily net heating rates in the northern hemisphere nh for the arctic late fall and winter periods of both 1988 1989 and 1991 1992 and in the southern hemisphere sh for the antarctic fall and winters of 1987 and 1992 the heating rates were interpolated to potential temperature surfaces between 400 k and 2000 k and averaged within the polar vortex the boundary of which was determined by the maximum gradient in potential vorticity the averaged heating rates were used in a one dimensional vortex interior descent model to compute the change in potential temperature with time of air parcels initialized at various values as well as to compute the descent in log pressure coordinates in the nh vortex air parcels which were initialized at 18 km on november 1 descended about 6 km by march 21 while air initially at 25 km descended 9 km in the same time period this represents an average descent rate in the lower stratosphere of 1 3 to 2 km per month air initialized at 50 km descended 27 km between november 1 and march 21 in the sh vortex parcels initialized at 18 km on march 1 descended 3 km while air at 25 km descended 5 7 km by the end of october this is equivalent to an average descent in the lower stratosphere of 0 4 to 0 9 km per month during this 8 month period air initialized at 52 km descended 26 29 km between march 1 and october 31 in both the nh and the sh computed descent rates increased markedly with height the descent for the nh winter of 1992 1993 and the sh winter of 1992 computed with a three dimensional trajectory model using the same radiation code was within 1 to 2 km of that calculated by the one dimensional model thus validating the vortex averaging procedure the computed descent rates generally agree well with observations of long lived tracers thus validating the radiative transfer model