climatology of upper tropospheric lower stratospheric utls jets and tropopauses in merra abstracta global climatology 1979 2012 from the modern era retrospective analysis for research and applications merra shows distributions and seasonal evolution of upper tropospheric jets and their relationships to the stratospheric subvortex and multiple tropopauses the overall climatological patterns of upper tropospheric jets confirm those seen in previous studies indicating accurate representation of jet stream dynamics in merra the analysis shows a northern hemisphere nh upper tropospheric jet stretching nearly zonally from the mid atlantic across africa and asia in winter spring this jet splits over the eastern pacific merges again over eastern north america and then shifts poleward over the north atlantic the jets associated with tropical circulations are also captured with upper tropospheric westerlies demarking cyclonic flow downstream from the australian and asian monsoon anticyclones and associated easterly jets multiple tropopauses associated with the thermal tropopause break

double tropopause formation in idealized baroclinic life cycles the key role of an initial tropopause inversion layer 1 recent studies have shown that double tropopauses exist in all seasons and at all longitudes in the midlatitudes as of yet the key mechanism responsible for their formation is not known in this study we explore the connection between double tropopauses and midlatitude baroclinic eddies this is investigated in the context of idealized life cycle experiments the key finding of this study is that large areas of double tropopauses form spontaneously at the nonlinear stage of the life cycle evolution provided an extratropical tropopause inversion layer is present in the balanced initial temperature profile we also show that the areas covered with double tropopauses grow as the strength of the initial tropopause inversion layer is increased without such a layer as in canonical examples of baroclinic life cycles much studied in the literature no double tropopause formation occurs in agreement with observations double tropopauses in our life cycle experiments form predominantly in areas of cyclonic flow at upper levels however the air masses that end up between the two tropopauses are found to originate from high latitudes this appears to differ from a recently published case study where the air between double tropopauses was shown to originate partly from low latitudes such a discrepancy suggests that more than one pathway may exist to advect air masses between the two tropopauses

sinkholes in italy first results on the inventory and analysis the italian geological survey apat carried out field surveys and analysis of collapse phenomena sinkholes in italy the main goal of the project is to collect geological geomorphological geochemical and hydrogeological data about the sinkhole prone areas in italy in order to develop a spatial database of the characteristics of each phenomenon the preliminary results of this study provide information on the distribution geological setting and monitoring and remediation actions associated with these natural collapses in italy many italian regions are affected by these natural disasters some of them are caused by karst collapses or anthropic activity however some occur in areas characterized by buried carbonate bedrock up to 190 m as well as by peculiar geological structural and geochemical scenarios in these areas it is not reasonable to ascribe the formation mechanism to karst activity instead these types of cavities quickly develop in terrains with a variable granulometry often in connection with upwelling fluids in this work some natural specific cases have been studied in order to define the relationships between the geology regional tectonic elements mineral spring waters and strong gas vents and the genesis of the sinkholes a first attempt of sinkhole classification is also presented

chemical and dynamical discontinuity at the extratropical tropopause based on start08 and waccm analyses 1 using isentropic trace gas gradients of o3 and co the discontinuity in the chemical composition of the upper troposphere ut and lower stratosphere ls is examined on middle world isentropes from 300 to 380 k the analysis is a follow up study of the dynamical discontinuity as represented by the potential vorticity pv gradient based tropopause which is based on the product of isentropic pv gradients and wind speed overall there is fairly good consistency between the chemical discontinuity in trace gas distributions and the pv gradient based tropopause trace gas gradients at the pv gradient based tropopause are stronger in winter than in summer revealing the seasonal cycle of the tropopause transport barrier the analysis of the trace gas gradients also identifies atmospheric transport pathways in the upper troposphere lower stratosphere utls several regions where trace gas gradients are found to be decoupled from the dynamical field indicate preferred transport pathways between the ut and ls in particular anomalous co and o3 gradients above eastern africa eastern asia and the west pacific are likely related to convective transport and anomalous o3 gradients over the north atlantic and north pacific are related to isentropic transport connected to frequent wave breaking the results indicate that the pv gradient based tropopause definition provides a good identification of the dynamical and chemical discontinuity and is therefore effective in locating the physical boundary in the utls

the double tropopause and its dynamical relationship to the tropopause inversion layer in storm track regions using high resolution dynamic limb sounder observations and era interim reanalysis this study demonstrates that the warm conveyor belt wcb is a mechanism responsible for the relationship between the double tropopause dt and the tropopause inversion layer til a relationship recently suggested in the literature based on idealized model simulations of baroclinic disturbances using these data sets spatial and temporal characteristics of the dt til relationship are examined over a 3 year period 2005 2008 in the extratropics results from satellite data show that as the til increases in strength so does the frequency of the dt regardless of season or hemisphere the inverse relationship is found in the tropics using only dt profiles zonal composites of wind relative vorticity and temperature from reanalysis data show that as the til increases in strength the upper tropospheric circulation switches from cyclonic to anticyclonic and the upward vertical motion increases this result suggests the wcb as a mechanism since it is on the anticyclonic side of the jet and is characterized by the movement of tropical air poleward and upward from the surface to verify this relationship the vertical and horizontal development of a synoptic scale baroclinic system is analyzed over a 4 day period results show the equatorward extension of the polar tropopause and thus the formation of the dt due to the strengthening of the til in the region of vertical motion associated with the wcb moreover this result suggests that air movement within the dt could originate from high latitudes when associated with a baroclinic disturbance

combined use of space borne sar interferometric techniques and ground based measurements on a 0 3km2 subsidence phenomenon abstract the built up area of the village hilsprich lorraine france is affected by a subsidence phenomenon localized over a few hundred square metres causing damage to buildings in this study differential sar interferometry dinsar was used to estimate the boundaries of the subsidence in order to optimize ground based monitoring networks levelling and geophysical measurements estimate the maximum deformation and highlight the evolution of the phenomenon previously unknown due to insufficient historical ground based data the study was based both on l band alos palsar sar data and c band envisat asar data the interest in palsar data lies in its better performance for insar with respect to c band data on the affected non urban areas such as fields and farmlands where in addition conventional techniques such as topographical survey information were limited and had often not been carried out before the first damage was observed conventional dinsar based on palsar data processing for the 2008 2010 period identified the boundary of the subsidence area and estimated its maximum magnitude the psi technique in the asar archive gave information regarding the beginning of the subsidence the precision of the dinsar results was consistent with the topographical data in locations where this information was known and therefore favours the sar interferometric techniques in this context combined with the knowledge of the regional geological and structural setting together with results from ground based electrosounding the results of the study established a basis for an increased understanding of the subsidence phenomenon which was revealed to affect an elliptical bowl shaped area due to salt dissolution

a new chemical lagrangian model of the stratosphere clams 1 formulation of advection and mixing 1 recent satellite observations and dynamical studies have demonstrated the existence of filamentary structures in chemical tracer fields in the stratosphere it is also evident that such features are often below the spatial resolution of the highest resolution eulerian models that have been used up to the present time these observations have motivated the development of a novel chemical lagranigan model of the stratosphere clams that is based on a lagrangian transport of tracers the description of clams is divided into two parts part 1 this paper concentrates on the lagrangian dynamics i e on the calculation of trajectories and on a completely new mixing algorithm based on a dynamically adaptive grid while part 2 describes the chemical integration and initialization procedure the mixing of different air masses in clams is driven by the large scale horizontal flow deformation and takes into account the mass exchange between the nearest neighbors determined by delaunay triangulation here we formulate an isentropic i e two dimensional version of the model and verify the mixing algorithm using tracer distributions measured during the space shuttle crista 1 experiment where highly resolved stratospheric structures were observed in early november 1994 a comparison of the measured southern hemispheric n2o distribution with clams results allows the intensity of simulated mixing to be optimized the long term robustness of the transport scheme is investigated in a case study of the 1996 1997 northern hemisphere polar vortex this study further provides a dynamical framework for investigations of chemical arctic ozone destruction discussed in part 2

a climatology of multiple tropopauses derived from gps radio occultations with champ and sac c 1 a global climatology of multiple tropopauses mt is discussed based on global positioning system gps radio occultation ro data from the german champ challenging minisatellite payload and the us argentinian sac c satelite de aplicaciones cientificas c satellite mission for the period may 2001 april 2005 in this study we present first detailed investigations about the geographical and temporal distribution of mt during different seasons the thickness of the layer between the lowest first and highest last tropopause has a strong annual cycle in the vicinity of the subtropical jet stj stream region values vary between 4 5 km during winter and 2 3 km during summer respectively whereas higher differences were found on the northern hemisphere it is shown that the occurrence distribution of mt is in good agreement with the mean climatological location of the stj 30 40 on both hemispheres in particular during winter time

sinkhole monitoring and early warning an experimental and successful gb insar application abstract sinkholes represent a natural risk that may hit catastrophically without clearly detectible precursors however they are often overlooked by people and administrators therefore sinkhole monitoring and associated early warnings constitute important research topics but currently only a few papers about sinkhole prediction can be found in this paper an experience of sinkhole monitoring and early warning with gb insar is described the latter is a highly precise instrument that is able to produce displacement maps with metric spatial resolution the described activities were carried out on elba island central italy where karstified limestone set off the occurrence of nine sinkholes since 2008 all within less than 3000 m2 causing major damage to an important road and many indirect losses in 1 year of monitoring two deforming areas were detected and the point where a sinkhole was about to propagate to the street level was predicted thus permitting the preventive closure of the road the deformation area was larger than the hole generated by the sinkhole thus showing a subsidence that continued for a prolonged time even after the cavity was filled up the occurrence of a 1 5 m wide sinkhole undetected by the gb insar also showed the lower detection limit of the instrument

development of collapse sinkholes in areas of groundwater discharge abstract collapse sinkholes are found in groundwater recharge zones throughout the world they cause substantial loss of property each year and occasional fatalities in such settings the formation of these features occurs through the downward migration of regolith into karst voids the presence of a void in the bedrock and sufficient seepage pressure or gravitative force in the regolith is required for their creation we investigated the development of cover collapse sinkholes in an unusual setting areas of groundwater discharge rather than recharge upward hydraulic gradients and the likelihood of groundwater saturated with respect to calcite are difficult to reconcile with standard models for collapse development short flowpaths or renewed groundwater aggressivity towards calcite via mischungskorrosion thermally driven circulation or deep seated gaseous sources are hypothetical mechanisms that could generate the subsurface voids that are needed to allow cover collapse development in discharge areas for the two field sites in central italy that we investigated calculated carbon dioxide partial pressures in springs ranged from 7 38 10 2 to 7 29 10 1 atm this indicates that deep seated gaseous sources are most likely the mechanism allowing the development of the sinkholes groundwater is recharged in surrounding limestone massifs the water moves through the carbonates and becomes saturated with calcite as it circulates deeply in to the adjacent valleys it mixes with deep seated waters and gaseous fluxes from major fault systems acquiring renewed aggressivity towards calcite finally the water ascends into confined aquifers in the valley fill and dissolves carbonate material present within leading to surface collapse

tropopause folds in era interim global climatology and relation to extreme weather events tropopause folds are intimately linked to upper level frontogenesis and jet stream dynamics they play an important role for stratosphere troposphere exchange the dynamical coupling of upper and lower tropospheric levels and for generating severe weather events this study presents a global climatology of tropopause folds using era interim reanalysis data from 1979 to 2012 and a refined version of a previously developed 3 d labeling and fold identification algorithm this algorithm objectively separates stratospheric and tropospheric air in complex situations e g in regions with strong low level inversions and in extratropical cyclones where diabatically generated potential vorticity anomalies typically occur three classes of tropopause folds are defined shallow medium and deep and their geographical distribution vertical extent and seasonal cycle are investigated most shallow folds occur along the subtropical jet stream in agreement with previous studies hot spots of medium and deep tropopause folds are found west of australia and along the coast of antarctica in the southern hemisphere and around the east coast of north america in the northern hemisphere seasonal cycles show maxima in winter for all fold classes medium and deep folds are frequently associated with surface wind gust and precipitation extremes as quantified for folds over the southern indian ocean wind gust extremes occur mainly in an elongated band upstream and equatorward of folds whereas precipitation extremes occur mainly east and poleward of folds overall in the considered region about 20 of medium folds and 33 of deep folds are associated with surface wind or precipitation extremes in the vicinity of the fold

fragmentation of stratospheric intrusions evidence is presented pointing to the existence of rich and coherent subsynoptic and mesoscale flow features at tropopause levels these features are related to and evolve from the classical v shaped intrusions of stratospheric air down to tropospheric elevations it is shown that intrusions can develop into elongated 2000 3000 km and slender 200 km streamers and that thereafter such a streamer can roll up to form a train of stalactite shaped vortex subentities with an accompanying substantial thinning of the intervening filament in addition there are indications that the vortices themselves can develop a spirallike interior structure of interleaved stratospheric and tropospheric air these inferences are based upon two independent but complementary sources analysis of the potential vorticity distribution on tropopause transcending isentropic surfaces derived from the analysis fields of the european centre for medium range weather forecasts either directly or indirectly using a contour advection technique and imagery from the water vapor channel of the european space agency meteosat 4 satellite streamers were observed to occur with a frequency of approximately one per week over central and southern europe during the winter of 1991 1992 the fragmentation is linked to the instability or self development of a filament of enhanced potential vorticity and it can modify or instigate surface weather systems moreover by inducing a substantial and rapid enlargement of the intrusion s surface area it greatly enhances the potential for local irreversible mixing of stratospheric and tropospheric air

a study of multiple tropopause structures caused by inertia gravity waves in the antarctic abstractmultiple tropopauses mts defined by the world meteorological organization are frequently detected from autumn to spring at syowa station 69 0 s 39 6 e the dynamical mechanism of mt events was examined by observations of the first mesosphere stratosphere troposphere mst radar in the antarctic the program of the antarctic syowa mst incoherent scatter is radar pansy and of radiosondes on 8 11 april 2013 the mt structure above the first tropopause is composed of strong temperature fluctuations by a detailed analysis of observed three dimensional wind and temperature fluctuation components it is shown that the phase and amplitude relations between these components are consistent with the theoretical characteristics of linear inertia gravity waves igws numerical simulations were performed by using a nonhydrostatic model the simulated mt structures and igw parameters agree well with the observation in the analysis using the numerical simulation data it is seen that igws were generate

influence of barotropic shear on the poleward advection of upper tropospheric air abstract the characteristics of the poleward advection of upper tropospheric air are investigated using meteorological analyses and idealized numerical models isentropic deformations of the tropopause during northern hemisphere winter are examined using maps of ertel s potential vorticity together with contour advection calculations large poleward excursions of upper tropospheric air are observed during rossby wave breaking events these poleward breaking events occur in regions of diffluence over the eastern atlantic ocean europe region and over the eastern pacific ocean north america region and the evolution of the tropospheric air depends on the local meridional shear in anticyclonic or weak cyclonic shear the tropospheric air tilts downstream broadens and wraps up anticyclonically whereas in cyclonic shear the tropospheric air tilts upstream thins and is advected cyclonically the role of ambient barotropic flow is further examined by considering the flow in two numerical models a pl

powder cloud eruptions where is the air reservoir and blow out motor in the rankine half body comment on role of pore pressure gradients in sustaining frontal particle entrainment in eruption currents the case of powder snow avalanches by m y louge et al

investigation of double tropopause spatial and temporal global variability utilizing high resolution dynamics limb sounder temperature observations 1 this study examines the seasonal variation of the double tropopause dt using data from the high resolution dynamics limb sounder the combination of high data density and high vertical resolution available with this satellite instrument allows for the detailed analysis of fine scale structures such as the dt the spatial distribution of dt frequency is examined for all seasons from 2005 to 2007 global analysis of this distribution reveals that dts have a strong tendency to follow the zonal wind pattern and are present all year over the andes moreover during northern hemisphere winter spring there is a 15 decrease in the dt frequency over the eastern pacific and western atlantic two regions of wave breaking produced from a weakening of the zonal flow significant dt thickness values are also present over these regions but are found to extend further poleward than the corresponding frequency pattern a time series of dt frequencies is analyzed and shows an increase in daily frequencies during 2006 that highlights the interannual variability of this thermal structure for the first time dt duration is investigated in the extratropics utilizing a hovmoller diagram of dt frequency this representation highlights two preferred regions of formation the pacific and atlantic the slope of the feature gives it a speed of 18 m s in the northern hemisphere and a slightly faster speed for the southern hemisphere these speeds and the corresponding structures highlight a potential connection between upper tropospheric waves and dts

evaluation of trenching ground penetrating radar gpr and electrical resistivity tomography ert for sinkhole characterization this paper explores the suitability and advantages of combining the trenching technique with geophysical surveys ground penetrating radar gpr and electrical resistivity tomography ert for sinkhole characterization in a mantled karst area the approach is applied to two active sinkholes concealed by anthropogenic deposits and formed by contrasting subsidence mechanisms collapse and sagging the ert section acquired across the collapse sinkhole images the clayey fill of the depression as an obvious low resistivity area showing the approximate location of the sinkhole edges spatially dense gpr surveys provide information on the position of the boundaries of the concealed subsidence structures and their three dimensional 3d internal geometry revealing the dominant subsidence mechanism we illustrate the impact of several factors on the quality of the gpr data such as sinkhole size nominal frequency of the antennas antenna shielding and the presence of backfilled excavations and above surface objects trenches provided detailed information on the subsurface structure of the sinkhole subsidence magnitude partitioning of the strain and the position of the sinkhole edges especially when they are deep enough and excavated across the central sector and perpendicular to the boundaries the stratigraphic and structural relationships observed in the trench were then used to infer the spatial evolution of the sinkholes e g enlargement their kinematic behavior episodic versus progressive and to differentiate discrete subsidence events and their associated magnitude numerical dates were used to estimate average subsidence rates and the recurrence of subsidence events such integrated data sets may be used as an objective basis to forecast the future behavior of potentially damaging sinkholes and to assess the associated hazard and risk copyright 2013 john wiley sons ltd

a lagrangian perspective of the tropopause and the ventilation of the lowermost stratosphere back trajectories driven by large scale analyzed wind fields are used to investigate troposphere to stratosphere transport tst in the northern hemisphere tropopause region as well as the surface sources for such transport defined in terms of the locations where each trajectory last left the atmospheric boundary layer log pressure height z 1 km the proportion chi bl of those trajectories arriving in the tropopause region that have visited the boundary layer within the previous fixed time period typically 30 days is determined as a function of each trajectory s final equivalent latitude and potential temperature for a range of potential temperature surfaces similar to 300 380 k chi bl is shown to have a sharp gradient in the extratropics indicative of a partial permeable barrier to transport that can be identified as a lagrangian tropopause variations in chi bl with equivalent latitude and potential temperature and on seasonal timescales are shown to provide a novel measure for the relative location and permeability of the tropopause barrier details such as the presence of a ventilated layer in the northern summer extratropical lower stratosphere similar to 370 410 k are clearly apparent directly below this layer 340 370 k the tropopause barrier to transport is shown to be relatively strong whereas below 340 k it is again more permeable a distinction can therefore be made between extratropical tst that primarily ventilates the lowermost stratosphere below 340 k and tropical tst that occurs into the 370 410 k ventilated layer the boundary layer source regions for extratropical tst are shown to correspond to those regions previously identified as sources for deep frontal uplift in the warm conveyor belt circulations of extratropical cyclones although elevated regions such as the himalayan plateau are also seen to be important tropical tst has different source regions associated with regions of active deep convection such as the western tropical pacific and in the northern summer the indian subcontinent the source regions are in general found to be geographically localized leading to the conclusion that subject to the limitations of the methodology trace gas emissions in specific regions are substantially more likely to be transported to the lowermost stratosphere than elsewhere the implications for the assessment of ozone depletion by very short lived halogenated species are mentioned

fine scale structure of the extratropical tropopause region 1 a vertically high resolved climatology of the thermal and wind structure of the extratropical tropopause region is presented the climatology is based on data from 80 u s radiosonde stations covering the period 1998 2002 time averages for each radiosonde station are computed using the tropopause as a common reference level for all vertical profiles within the mean a strong inversion at the tropopause in the mean vertical temperature gradient is uncovered that is temperature strongly increases with altitude within the lowermost stratosphere this tropopause inversion layer exists on average throughout the investigated extratropics about 30 n to 70 n accordingly the static stability parameter shows considerably enhanced values within the lowermost extratropical stratosphere compared to typical extratropical stratospheric values further aloft conventional averages are not able to capture the tropopause inversion layer mean profiles of the horizontal wind show behavior qualitatively corresponding to thermal wind balance winter and summer exhibit distinctly different climate states in the extratropical tropopause region an approximated potential vorticity is considered and found to be close to well mixed within the troposphere as well as within the tropopause inversion layer this suggests the view of the tropopause inversion layer as representing a dynamically active atmospheric layer some potential implications are discussed

bayou corne louisiana sinkhole precursory deformation measured by radar interferometry catastrophic sinkholes are formed through the collapse of natural or human made subterranean caverns and are common in areas with evaporite and carbonate rock despite their danger advance warning of these events is rare we report a measurement of precursory surface deformation of as much as 260 mm derived with interferometric synthetic aperture radar insar and evident over a month before surface collapse at the site of the bayou corne louisiana usa sinkhole that formed in august 2012 data collected by the airborne uninhabited aerial vehicle sar uavsar instrument were used for the study analysis of data acquired from two flight tracks with near opposing imaging geometries reveal a deformation pattern consistent with compressive loading at the surface due to loss of support from a subterranean cavity collapse related to texas brine oxy geismar well 3 the precursor deformation was nearly entirely horizontal i e oriented along the surface and manifested as movement of surface material toward the location where the sinkhole later formed the sinkhole formed in the area with the largest gradient in surface strain but did not cover the full extent of the precursory deformation detected with radar this work suggests that insar data collected operationally for hazard monitoring could in some cases identify sinkhole development before surface collapse and decrease subsequent danger to people and property

tropospheric intrusions associated with the secondary tropopause 1 deep intrusions of tropospheric air into the lower stratosphere above the subtropical jet are investigated using new observations and meteorological analyses these intrusions are characterized by low ozone concentration and low static stability the low ozone layer is consistently observed from ozonesonde profiles and satellite remote sensing data from aura hirdls the intruding layer occurs along and under the poleward extending tropical tropopause which becomes the secondary tropopause in middle to high latitudes the association of the ozone and the thermal structure provides evidence for the physical significance of the subtropical tropopause break and the secondary tropopause the core of the intruding layer is typically between 370 and 400 k potential temperature 15 km but the vertical extent of the intrusion can impact ozone above 400 k the lower boundary of the overworld two intrusion events over the continental united states in the spring of 2007 are analyzed to show the spatial extent and the temporal evolution of the intruding air mass these examples demonstrate the effectiveness of potential temperature lapse rate i e static stability as a diagnostic for the intrusion event comparison with the potential vorticity field is made to show the complementarity of the two dynamical fields the static stability diagnostic provides a tool to map out the horizontal extent of the intruding layer and to investigate its evolution furthermore the diagnostic makes it possible to forecast the intrusion event for field studies

association of double tropopause events with baroclinic waves 1 we herein propose a method for identifying breaks in the subtropical tropopause as found in the era interim reanalysis data the method uses the identification of double tropopauses and allows the quantification of the extension of the overlap between the tropical and extratropical tropopauses the correlations between the meridional extension of the superposition of tropopauses and the fields of geopotential potential vorticity or potential temperature reveal baroclinic wave patterns similar wave patterns were also identified in the potential temperature fields derived from gps radio occultation cosmic data the zonal propagation velocity of the anomalies in the meridional extension of the overlap was estimated using hovmoller diagrams the estimated zonal velocities suggest that the variability in the superposition of the tropopauses is associated with baroclinic rossby wave patterns in the subtropical upper troposphere and lower stratosphere

stratosphere to troposphere transport revealed by ground based lidar and ozonesonde at a midlatitude site 1 this paper presents ozone structures measured by a ground based ozone lidar and ozonesonde at huntsville alabama on 27 29 april 2010 originating from a stratosphere to troposphere transport event associated with a cutoff cyclone and tropopause fold in this case the tropopause reached 6 km and the stratospheric intrusion resulted in a 2 km thick elevated ozone layer with values between 70 and 85 ppbv descending from the 306 k to 298 k isentropic surface at a rate of 5 km day 1 the potential temperature was provided by a collocated microwave profiling radiometer we examine the corresponding meteorological fields and potential vorticity pv structures derived from the analysis data from the north american mesoscale model the 2 pvu pv unit surface defined as the dynamic tropopause is able to capture the variations of the ozone tropopause estimated from the ozonesonde and lidar measurements the estimated ozone pv ratio from the measured ozone and model derived pv for the mixing layer between the troposphere and stratosphere is 41 ppbv pvu with an uncertainty of 33 within two days the estimated mass of ozone irreversibly transported from the stratospheric into the troposphere is between 0 07 tg 0 9 1033 molecules and 0 11 tg 1 3 1033molecules with an estimated uncertainty of 59 tropospheric ozone exhibited enormous variability due to the complicated mixing processes low ozone and large variability were observed in the mid troposphere after the stratospheric intrusion due to the westerly advection including the transition from a cyclonic system to an anticyclonic system this study using high temporal and vertical resolution measurements suggests that in this case stratospheric air quickly lost its stratospheric characteristics once it is irreversibly mixed down into the troposphere

double tropopauses and the tropical belt connected to enso a detailed analysis of double tropopause dt occurrences requires vertically well resolved accurate and globally distributed information on the troposphere stratosphere transition zone here we use radio occultation observations from 2001 to 2018 with such properties we establish a connection between el nino southern oscillation enso phases and the distribution of dts by analyzing the global and seasonal dt characteristics the seasonal distribution of dts reveals several hotspot locations such as near the subtropical jet stream and over high mountain ranges where dts occur particularly often in this study we detect a higher number of dts during the cold la nina state while warmer el nino events result in lower dt rates affecting the structure of the tropopause region close to the nino 3 region this relates to a much lower first lapse rate tropopause altitude during la nina and corresponds to an apparent narrowing of the tropical belt there

dinsar measurements of ground deformation by sinkholes mining subsidence and landslides ebro river spain differential interferometric synthetic aperture radar dinsar has been applied to detect and measure ground deformation in a stretch of the ebro river valley spain excavated in salt bearing evaporites the capability of the small baseline subset sbas dinsar technique to detect ground displacement is analyzed comparing the dinsar results with the available geomorphological information the deformation map derived from 27 european remote sensing ers satellite images covering more than five years provides sub centimeter displacement measurements in zones coinciding with known active sinkholes and landslides moreover the map provides the first account of mining subsidence in the area the measured deformation rates reach 1 68 cm y for the sinkholes 0 80 cm y for the landslides and 1 45 cm y for the area affected by mining subsidence the sbas dinsar technique provided deformation measurements in a small proportion 5 10 of the known active sinkholes and landslides this limitation is mainly due to the lack of coherence in agricultural areas the spatial resolution of the deformation map pixel size of 90 m and the parallelism between the ers satellite line of sight and the linear escarpment on which most of the landslides occur despite this the interferometric technique provides valuable data that complement traditional geomorphological studies including the quantification of the deformation phenomena the identification of mining subsidence otherwise only recognizable by geodetic methods and the detection of creep deformation which might correspond to premonitory indicators of catastrophic sinkholes and landslides capable of causing the loss of lives detailed dinsar studies combined with field data would be required to improve the analysis of each deformation area copyright 2009 john wiley sons ltd

the extratropical tropopause inversion layer global observations with gps data and a radiative forcing mechanism global characteristics of the extratropical tropopause inversion layer identified in radiosonde observations by birner are studied using high vertical resolution temperature profiles from gps radio occultation measurements the gps data are organized according to the height of the thermal tropopause in each profile and a temperature inversion layer above the tropopause with an average magnitude of 3 5 k is found to be a ubiquitous climatological feature the gps data show that the inversion layer is present for all seasons in both hemispheres spanning the subtropics to the pole and there is not strong longitudinal structure dependence of the inversion layer on upper troposphere vorticity is studied while anticyclones exhibit a substantially stronger inversion than cyclones as expected from balanced dynamics the inversion is evident for all circulation types radiative transfer calculations indicate that strong gradients in both ozone and water vapor near the tropopause contribute to the inversion significant absorption of both longwave and shortwave radiation by ozone occurs warming the region above the tropopause water vapor near and immediately above the tropopause contributes to cooling effectively enhancing the inversion

characteristics of the subtropical tropopause region based on long term highly resolved sonde records over tenerife 1 this study examines the structure of the subtropical tropopause region over tenerife the canary islands spain 28 n 16 w based on a 20 year 1992 2011 ozonesonde data and european center for medium range weather forecasts era interim potential vorticity pv and zonal wind speed reanalysis high resolution vertical profiles allowed a detailed description of the subtropical tropopause break and the associated subtropical jet stream stj where models fail to properly simulate the upper troposphere lower stratosphere utls the subtropical utls is revealed as a complex atmospheric region with a thickness 8 km which is examined through the analysis and evaluation of four different tropopause definitions thermal tt cold point ozone ot and dynamical dt tropopauses a novel method to determine the dt based on the vertical gradient of lait s modified pv is presented and the concept of a second dt has been introduced for the first time monthly climatologies of tropopause height and potential temperature are calculated for double and single tropopause events the 14 3 km height level is used to differentiate between tropical and extratropical utls regimes intimately linked to the position of the stj there is fairly good consistency between all the defined tropopauses under the double tropopause scheme except in spring when the ot is observed at lower levels due to frequent baroclinic instabilities in the upper troposphere as concerns to single tropopause events the same pattern is found from april to june reflecting the influence of analogous processes during these months in winter altitude differences between ot dt and tt resulted from poleward stj excursions forced by blocking systems over the north atlantic analysis of the tropopause inversion layer showed distinctive features for tropical and midlatitude tropopauses

a climatology of rossby wave breaking along the subtropical tropopause ten years 1986 95 of global analyses from the european centre for medium range weather forecasts are used to investigate the temporal and spatial distributions of rossby wave breaking rwb at 350 k along the tropopause herein defined by the 61 5 potential vorticity pv unit 10 26 km 2 s21 kg21 contours though many studies acknowledge rwb as an important contributor to the complex of mixing processes in the atmosphere there exists no prior climatological study of its distribution near the tropopause as in previous studies rwb is identified in the global analyses by southward directed pv gradients at 350 k rwb along the tropopause occurs preferentially during summer over the midoceans in relative proximity to the planetary scale high pressure systems in the subtropics isentropic trajectories at 350 k show that outflow from the tops of these subtropical highs directly participates in rwb over the adjacent downstream oceanic regions two regions are highlighted in this study the north pacific during boreal summer and the south atlantic during austral summer synoptic maps of breaking rossby waves in these regions are provided to reveal the acute tropopause folding in the meridional plane which characteristically accompanies rwb the rich interaction between the tropical flow and the extratropical westerly current exhibited by these cases suggests that the subtropical highs serve as important agents in the coupling between the tropical troposphere and the extratropical stratosphere as expected from theoretical considerations the locations where rwb occurs most frequently known as surf zones are shown to coexist with regionally weak time mean wind speeds and horizontal gradients of pv at 350 k