variability of the north atlantic thermohaline circulation during the last interglacial period studies of natural climate variability are essential for evaluating its future evolution greenland ice cores suggest that the modern warm period the holocene has been relatively stable for the past 9 000 years much less is known about other warm interglacial periods which comprise less than 10 of the climate record during the past 2 5 million years here we present high resolution ocean sediment records of surface and deep water variables from the bermuda rise spanning the last interglacial period about 118 000 127 000 years ago in general deep water chemical changes are coincident with transitions in surface climate at this site the records do not show any substantial fluctuations relative to the much higher variability observed during the preceding and subsequent cool climates the relatively stable interglacial period begins and ends with abrupt changes in deep water flow we estimate using 230 th measurements to constrain the chronology that transitions occur in less than 400 years

correction for the static shift in magnetotellurics using transient electromagnetic soundings shallow inhomogeneities can lead to severe problems in the interpretation of magnetotelluric mt data by shifting the mt apparent resistivity sounding curve by a scale factor which is independent of frequency on the standard log apparent resistivity versus log frequency display the amount of parallel shift commonly referred to as the mt static shift can not be determined directly from conventionally recorded mt data at a single site one method for measuring the static shift is a controlled source measurement of the magnetic field unlike the electric field the magnetic field is relatively unaffected by surface inhomogeneities the controlled source sounding which may be a relatively shallow sounding made with lightweight equipment can be combined with a deep mt sounding to obtain a complete undistorted model of the earth inversions of the static shift corrected mt data provide a much closer match to well log resistivities than do inversions of the uncorrected data the particular controlled source magnetic field sounding which we used was a central induction transient electromagnetic tem sounding correction for the static shift in the mt data was made by jointly inverting the mt data and the tem data a parameter which allowed vertical shifts in the mt apparent resistivity curves was included in the computer inversion to account for static shifts a simple graphical comparison between the mt apparent resistivities and the tem apparent resistivities produced essentially the same estimate of the static shift within 0 1 decade as the joint computer inversion central induction tem measurements were made adjacent to over 100 mt sites in central oregon the complete data base of over 100 sites showed an average static shift between 0 and 0 2 decade however in the rougher topography and more complex structure of the cascade mountain range the majority of the sites had static shifts of the order of 0 3 to 0 4 decade the static shifts in this area are probably due to a combination of topography and surficial inhomogeneities the tem apparent resistivity which is used to estimate the unshifted mt apparent resistivity does not necessarily agree with either the transverse electric te or the transverse magnetic tm mt polarization tem apparent resistivity may occur between the two or may agree with one of the two polarizations or may lie outside the mt polarizations

thermal structure of jupiter s atmosphere near the edge of a 5 μm hot spot in the north equatorial belt thermal structure of the atmosphere of jupiter was measured from 1029 km above to 133 km below the 1 bar level during entry and descent of the galileo probe the data confirm the hot exosphere observed by voyager 900 k at 1 nanobar the deep atmosphere which reached 429 k at 22 bars was close to dry adiabatic from 6 to 16 bars within an uncertainty 0 1 k km the upper atmosphere was dominated by gravity waves from the tropopause to the exosphere shorter waves were fully absorbed below 300 km while longer wave amplitudes first grew then were damped at the higher altitudes a remarkably deep isothermal layer was found in the stratosphere from 90 to 290 km with t 160 k just above the tropopause at 260 mbar there was a second isothermal region 25 km deep with t 112 k between 10 and 1000 mbar the data substantially agree with voyager radio occultations the voyager 1 equatorial occultation was similar in detail to the present sounding through the tropopause region the voyager iris average thermal structure in the north equatorial belt neb approximates a smoothed fit to the present data between 0 03 and 400 mbar differences are partly a result of large differences in vertical resolution but may also reflect differences between a hot spot and the average neb at 15 4 bars probe descent velocities derived from the data are consistently unsteady suggesting the presence of large scale turbulence or gravity waves however there was no evidence of turbulent temperature fluctuations 0 12 k a conspicuous pause in the rate of decrease of descent velocity between 1 1 and 1 35 bars where a disturbance was also detected by the two radio doppler experiments implies strong vertical flow in the cloud seen by the probe nephelometer at p 0 6 bar measured temperatures were 3 k warmer than the dry adiabat possible evidence of radiative warming this could be associated with a tenuous cloud detected by the probe nephelometer above the 0 51 bar level for an ammonia cloud to form at this level the required abundance is 0 20 solar

properties of the lithosphere asthenosphere system in europe with a view toward earth conductivity over the past 20 years the study ofp ands wave velocities in the upper mantle of the mediterranean area and continental europe has been the subject of intensive research work we present a summary of results based on the inversion of available surface wave dispersion data andp wave trave time observations for areas characterized by different tectonic settings and very large lateral variations a discussion is made about structural models based on seismological geothermal and electrical conductivity data

galileo imaging of jupiter s atmosphere the great red spot equatorial region and white ovals during the first six orbits of the galileo spacecraft s prime mission the solid state imaging ssi system acquired multispectral image mosaics of jupiter s great red spot an equatorial belt zone boundary a 5 m hot spot similar to the galileo probe entry site and two of the classic white ovals we present mosaics of each region approximating their appearance at visible wavelengths and showing cloud height and opacity variations the local wind field is derived by tracking cloud motions between multiple observations of each region with time separations of roughly 1 and 10 hr vertical cloud structure is derived in a companion paper by banfieldet al icarus135 230 250 galileo s brief high resolution observations complement earth based and voyager studies and offer local meteorological context for the galileo probe results our results show that the dynamics of the zonal jets and large vortices have changed little since voyager with a few exceptions we detect a cyclonic current within the center of the predominantly anticyclonic great red spot the zonal velocity difference between 0 s and 6 s has increased by 20 m sec 1 we measure a strong northeast flow approaching the hot spot this flow indicates either massive horizontal convergence or the presence of a large anticyclonic vortex southeast of the hot spot the current compact arrangement of two white ovals and a cyclonic structure greatly perturbs the zonal jets in that region

comparison of the structure and dynamics of jupiter s great red spot between the voyager 1 and 2 encounters abstract we have consistently navigated the highest resolution images available of jupiter s great red spot grs from the voyager iss experiment from them we have measured apparent displacements of cloud features around and within the red spot which can be interpreted as wind vectors we have used the wind field information to determine the circulation characteristics of the collar and to map the relative vorticity and horizontal divergence of the central grs region color ratios and ground based data have been used to complement these observations derived quantities from the iris data set taken simultaneously with the voyager images have been obtained in order to determine the thermal structure infrared cloud opacity nh 3 abundance and para h 2 fraction above the great red spot there is evidence of non chaotic activity in the central region of the red spot small eddy structures consisting of coherent cloud features with apparently two dimensional turbulent motions are present in this region along with larger classical cyclonic vortices the surrounding anticyclonic collar circulates with higher velocities and appears to be detached from the core by an abrupt transition region the central region appears to be elevated over the surrounding collar and exhibits evidence for upwelling and some outflow of material differences in the collar structure and velocity profiles between the voyager encounters can be attributed to differences in the ingestion rate of westward moving south equatorial belt vortices caused by a blocking south tropical zone disturbance which moving eastward overtook and passed the red spot between the two encounters this disturbance appears to temporarily increase in brightness during conjunctions with the red spot and has been tracked for 20 years

h3 as an ionospheric sounder of jupiter and giant planets an observational perspective thirty years of observations of h3 on jupiter have addressed many complex questions about the physics of the ionospheres of the giant planets spectroscopy imaging and imaging spectroscopy in the

magnetotelluric and seismological determination of the lithosphere asthenosphere transition in central europe abstract we assembled all available magnetotelluric mt sounding curves that cover characteristic provinces of europe the depths of layers with increased electrical conductivities estimated from mt sounding curves by the respective authors were compared with a model of the lithosphere thickness derived from seismic p residuals regions of a relatively thin and thick lithosphere are characterized by positive and negative p residuals respectively we have found a good correspondence with both sets of results in the central part of the pannonian basin the depth of the lithosphere asthenosphere transition is estimated at 60 80 km and 100 120 km at the flanks the results for the bohemian massif show deeper levels of this transition between 100 and 200 km these depths seem to be typical of the lithosphere base beneath the variscan domain of central europe

why is the h3 hot spot above jupiter s great red spot so hot recent observations of jupiter s great red spot indicate that the thermosphere above the storm is hotter than its surroundings by more than 700 k possible suggested sources for this heating have t

an interpretive analysis of magnetotelluric data a simple analysis to determine the dimensionality of magnetotelluric resistivity variations to separate the near surface resistivity variation from the variations at depth and to find the relative resistivity variations with depth is described parameters derived from the magnetotelluric impedance tensor are mapped in pseudosection and planar view for two dimensional 2 d model data and for survey data from montana these data illustrate procedures that can qualitatively map complex resistivity structures in the lateral distance frequency domain or equivalently the lateral distance scaled vertical distance domain phase dependent parameters have better vertical resolution than parameters related to scalar apparent resistivity but the latter allow estimates of the resistivities encountered phase parameters for the montana data provide a semiquantitatively accurate cross section of a geologically known anticlinal structure this suggests a means of subsurface structural mapping with magnetotelluric data the use of these parameters with sufficiently dense and accurate data provides a first order indication of structure for subsequent quantitative modeling

new observational results concerning jupiter s great red spot the changing size and aspect ratio of the great red spot from 1880 to 2000 are reviewed indicating that the length of the system has decreased significantly over the last 100 years and continues to decrease at present at a rate of 0 19 degrees per year voyager iris maps of para hydrogen fraction and potential temperature over the system are presented showing the internal structure and surrounding areas at pressures from 100 to 500 mbars in these maps the grs appears as a cold temperature anomaly and a low para fraction anomaly vertical structure analyses and wind velocity measurements are presented from data acquired by the galileo spacecraft in 1996 and 2000 respectively the vertical structure data suggest a very thick white cloud deck with a top near 800 100 mbars and an extended blue absorbing optically thick haze up to about 200 mbars with a thin stratospheric haze above it the wind field shows a substantial increase in the maximum tangential velocity from 150 to 190 m s 1 over the galileo time period the vertical structure analyses from galileo data and the wind and temperature fields from voyager data all show evidence of a tilt to the great red spot at the cloud deck from north to south and more subtly from east to west the data support the hypothesis of the grs as a tilted pancake with temporal variability to the tilt

climate records and changes in deep outflow from the norwegian sea 150 55 ka in order to contribute to our understanding of the linkage between climate and ocean circulation we have studied benthic foraminifera from near the northern end of the faeroe shetland channel covering isotope stages 6 to lower stage 3 150 55 ka our records demonstrate shifts between recurring assemblages which on millennial timescales monitor the outflow history of norwegian sea deep water the records show that the outflow is closely linked to the climate of the region as documented in the greenland ice cores outflow was relatively strong during all major warmer interstadials whereas there was no outflow during the colder stadials during isotope substage 5e outflow was stable for 10 12 kyr with significant changes at the beginning and end only

thermal structure and composition of jupiter s great red spot from high resolution thermal imaging abstract thermal ir imaging from space borne and ground based observatories was used to investigate the temperature composition and aerosol structure of jupiter s great red spot grs and its temporal variability between 1995 and 2008 an elliptical warm core extending over 8 of longitude and 3 of latitude was observed within the cold anticyclonic vortex at 21 s the warm airmass is co located with the deepest red coloration of the grs interior the maximum contrast between the core and the coldest regions of the grs was 3 0 3 5 k in the north south direction at 400 mbar atmospheric pressure although the warmer temperatures are present throughout the 150 500 mbar range the resulting thermal gradients cause counter rotating flow in the grs center to decay with altitude into the lower stratosphere the elliptical warm airmass was too small to be observed in irtf imaging prior to 2006 but was present throughout the 2006 2008 period in vlt subaru and gemini imaging spatially resolved maps of mid ir tropospheric aerosol opacity revealed a well defined lane of depleted aerosols around the grs periphery and a correlation with visibly dark jovian clouds and bright 4 8 m emission ammonia showed a similar but broader ring of depletion encircling the grs this narrow lane of subsidence keeps red aerosols physically separate from white aerosols external to the grs the visibility of the 4 8 m bright periphery varies with the mid ir aerosol opacity of the upper troposphere compositional maps of ammonia phosphine and para h 2 within the grs interior all exhibit north south asymmetries with evidence for higher concentrations north of the warm central core and the strongest depletions in a symmetric arc near the southern periphery small scale enhancements in temperature nh 3 and aerosol opacity associated with localized convection are observed within the generally warm and aerosol free south equatorial belt seb northwest of the grs the extent of 4 8 m emission from the seb varied as a part of the 2007 global upheaval though changes during this period were restricted to pressures greater than 500 mbar finally a region of enhanced temperatures extended southwest of the grs during the survey restricted to the 100 400 mbar range and with no counterpart in visible imaging or compositional mapping the warm airmass was perturbed by frequent encounters with the cold airmass of oval ba but no internal thermal or compositional effects were noted in either vortex during the close encounters

a granite window to the lower electrical crust and upper mantle the structure and properties of the deep crust and upper mantle can be investigated using magnetotelluric observations near surface and upper crustal complexities may distort or limit the capability of the data to adequately resolve deep structure granite batholiths have been regarded as windows into the lower crust in the context of seismic re ection data although the granite bodies themselves are not usually detected magnetotelluric data from sw england are here used to demonstrate that in addition to imaging the internal structure and base of a granite the batholith itself provides a suitable environment for the effective estimation of the resistivity structure to lower crustal and upper mantle depths

jupiter s ionosphere results from the first galileo radio occultation experiment the galileo spacecraft passed behind jupiter on december 8 1995 allowing the first radio occultation measurements of its ionospheric structure in 16 years at ingress 24 s 68 w the principal peak of electron density is located at an altitude of 900 km above the 1 bar pressure level with a peak density of 105 cm 3 and a thickness of 200 km at egress 43 s 28 w the main peak is centered near 2000 km altitude with a peak density of 2 104 cm 3 and a thickness of 1000 km two thin layers possibly forced by upwardly propagating gravity waves appear at lower altitudes in the ingress profile this is the first in a two year series of observations that should help to resolve long standing questions about jupiter s ionosphere

major crustal reflectors beneath sw england strong wide angle reflection events were detected during a crustal seismic experiment carried out in sw britain in 1979 three crustal reflectors have been identified referred to as rl r2 and r3 rl lies at a depth of about 8 km and appears to be restricted to the interior of the granite batholith underlying sw england the nature of this reflector is unknown r2 is a mid crustal reflector lying at a depth of 10 15 km and interpreted as rising gradually northwards it coincides locally with the base of the granite as predicted by gravity modeling but extends well beyond the northern limit of the granite body it is suggested that r2 may represent a major thrust of late variscan age r3 is the deepest reflector identified and lies at a depth of 27 30 km r3 is interpreted as the base of the crust and its computed depth is in close agreement with the local depth to the moho derived from an earlier seismic experiment in sw britain

geophysical images of the deep crust the iapetus suture the iapetus suture arguably the most fundamental lineament of british and irish structure has been previously identified on the birps winch deep seismic reflection profiles offshore as a nw dipping feature new depth migrated interpretations of these and other reflection data show good correlation of structure for 100 km along strike in the northern irish sea towards magnetotelluric stations onshore in the north of england and southern uplands of scotland three different methods of inverting data from these sites all reveal a thin nw dipping slab of high conductivity a contour map of the suture trace dipping at 15 25 nw can be constructed down to and through the moho at 28 km depth this map suggests crustal stretching below the solway basin the mylonitic suture zone is characterized by good seismic reflection layering high conductivity presumably fluid produced and a steep increase of p wave velocity over the few kilometres of its width crustal refraction experiments lispb and cssp provide useful velocities but locally misleading structure so that the combination of the seismic reflection and geoelectric methods may be the most powerful means of determining deep crustal structure with a good degree of both vertical and lateral resolution

on the electrical crust mantle structure in fennoscandia no moho and the asthenosphere revealed summary an interpretation of the geomagnetic inductive response function c 0 observed at kiruna in northern sweden is herein undertaken the bounds of acceptable solutions are initially discovered by a monte carlo random search procedure and the best fitting solutions are examined by the application of linear theory to the problem the data are shown to have a higher degree of internal consistency than that described by the estimated variances of each datum a further monte carlo inversion of the variance reduced data set gives solutions with well defined model parameters the two major features of the models are 1 a small or non existent electrical conductivity variation across the seismic moho boundary and 2 the unequivocal existence of an electrical asthenosphere under the fenno scandian shield beginning at a depth of between 155 185 km and of 60km minimum thickness both of these observations have seismic counterparts finally possible mantle temperature profiles are deduced which depend on the assumptions and laboratory data employed

high resolution stratigraphy of the faeroe shetland channel and its relation to north atlantic paleoceanography the last 87 kyr abstract two piston cores from the faeroe shetland channel have been investigated for stratigraphic and paleoceanographic correlation with atlantic ocean and norwegian sea records the high resolution cores have been analyzed for the downcore distribution of planktic and benthic foraminifera and oxygen isotopes ams 14 c dates and the position of ash layers i and ii form the basis for the correlation core na81 10 covers the period from isotope stage 3 to recent stage 1 while core na81 04 covers isotope stages 5a to 1 the holocene is well represented in core na81 10 by 2 m of sediment whereas it is only 50 cm in core na81 04 which is situated directly under the main core of the norwegian sea deep water outflow the transition of isotope stage 2 to stage 1 is affected by dissolution and thus is less clearly represented ams 14 c dates show that termination ia begins at 16 ka and ends at about the 13 ka level the last glacial maximum lgm defined at 19 16 ka is characterized by an ird peak faunal planktic foraminifera maxima dated at 17 3 and 18 25 ka and a high percentage of globigerina quinqueloba apparently open water conditions and circulation within the norwegian sea prevailed at least from 22 5 to 14 8 ka during the greatest part of stage 2 including the lgm and well onto termination ia a preservation maximum is observed throughout stage 2 isotope stage 3 with a nearly complete record of isotope substages is well represented in both cores oxygen isotope depletion peaks correlate with fauna minima and in time to north atlantic heinrich events h5 h1 faunal data indicate that deep water is generated within the norwegian greenland sea repeatedly since 26 ka with stops prior to 26 ka 22 5 20 8 20 5 ka and between 14 9 and 13 ka h3 h2 and h1 all isotope depletion peaks since ca 50 ka are anticorrelated with fauna and are mainly controlled by surface salinity changes isotope stages and substages are directly correlated to fauna peaks and temperature between 87 and ca 50 ka the faeroe shetland channel record shows that repeated presences of atlantic surface water and deep convection alternating with convection shutdowns have occurred within the norwegian sea greenland sea from the beginning of stages 5a to 1