nonlinear simulations of jupiter s 5 micron hot spots large scale nonlinear simulations of jupiter s 5 micron hot spots produce long lived coherent structures that cause subsidence in local regions explaining the low cloudiness and the dryness measured by the galileo probe inside a hot spot like observed hot spots the simulated coherent structures are equatorially confined have periodic spacing propagate west relative to the flow are generally confined to one hemisphere and have an anticyclonic gyre on their equatorward side the southern edge of the simulated hot spots develops vertical shear of up to 70 meters per second in the eastward wind which can explain the results of the galileo probe doppler wind experiment

determination of venus winds by ground based radio tracking of the vega balloons a global array of 20 radio observatories was used to measure the three dimensional position and velocity of the two meteorological balloons that were injected into the equatorial region of the venus atmosphere near venus midnight by the vega spacecraft on 11 and 15 june 1985 initial analysis of only radial velocities indicates that each balloon was blown westward about 11 500 kilometers 8 000 kilometers on the night side by zonal winds with a mean speed of about 70 meters per second excursions of the data from a model of constant zonal velocity were generally less than 3 meters per second however a much larger variation was evident near the end of the flight of the second balloon consistent systematic trends in the residuals for both balloons indicate the possibility of a solar fixed atmospheric feature rapid variations in balloon velocity were often detected within a single transmission 330 seconds however they may represent not only atmospheric motions but also self induced aerodynamic motions of the balloon

vertical wind shear in neptune s upper atmosphere explained with a modified thermal wind equation abstract we present observations of neptune taken in h 1 4 1 8 m and k 2 0 2 4 m bands on the nights of july 3 2013 and august 20 2014 from the 10 m w m keck ii telescope using nirc2 coupled to the adaptive optics ao system we track the positions of 100 bright atmospheric features over a 4 5 h window on each night to derive zonal velocities and wind profiles our results deviate from the smooth voyager zonal wind profile from sromovsky et al 1993 often by 100 200 m s and often by 3 10 times their estimated uncertainties besides what appears to be a random dispersion probably due to a mix of unaccounted for measurement errors eddy motions vertical wind shear and wave generated features that do not follow the mass flow there is also a systematic deviation that is wavelength dependent the h band profile is best described with a 73 106 m s shift towards the east for a retrograde flow i e a lessening of the retrograding velocities from the voyager profile at the equator the k band profile is consistent with voyager on both nights comparing h and k contribution functions and k h intensities suggests equatorial h band features are on average deeper than k band features the h band equatorial features also have greater eastward less negative velocities than k band features differences in zonal wind speed with depth at constant latitude and time imply vertical wind shear assuming the average variations in the zonal wind profiles result from wind shear over 3 5 scale heights we predict vertical wind shears between 1 0 and 2 2 m s km at the equator increasing with height the standard thermal wind equation and meridional thermal profile for neptune given by voyager iris spectra predict wind shear of the wrong sign relative to the observations we consider two effects that reconcile this inconsistency first we calculate the meridional temperature gradients at pressures outside the voyager iris narrow sensitivity window required to match our predicted wind shears second we generalize to a thermal wind equation that considers global methane variations and re derive the temperature structure needed to match the observed wind shear if methane is uniformly distributed or weakly varying the equator must be 2 15 k cooler than the mid latitudes below 1 bar if methane is strongly varying the equator can be 2 3 k warmer than the mid latitudes below 1 bar qualitatively consistent with observed temperature contrasts these findings may imply a stacked celled circulation pattern in neptune s troposphere and lower stratosphere

the galileo probe doppler wind experiment measurement of the deep zonal winds on jupiter during its descent into the upper atmosphere of jupiter the galileo probe transmitted data to the orbiter for 57 5 min accurate measurements of the probe radio frequency driven by an ultrastable oscillator allowed an accurate time history of the probe motions to be reconstructed removal from the probe radio frequency profile of known doppler contributions including the orbiter trajectory the probe descent velocity and the rotation of jupiter left a measurable frequency residual due to jupiter s zonal winds and microdynamical motion of the probe from spin swing under the parachute atmospheric turbulence and aerodynamic buffeting from the assumption of the dominance of the zonal horizontal winds the frequency residuals were inverted and resulted in the first in situ measurements of the vertical profile of jupiter s deep zonal winds a number of error sources with the capability of corrupting the frequency measurements or the interpretation of the frequency residuals were considered using reasonable assumptions and calibrations from prelaunch and in flight testing it is found that beneath the cloud tops about 700 mbar the winds are prograde and rise rapidly to 170 m s at 4 bars beyond 4 bars to the depth at which the link with the probe was lost nearly 21 bars the winds remain constant and strong corrections for the high temperatures encountered by the probe have recently been completed and provide no evidence of diminishing or strengthening of the zonal wind profile in the deeper regions explored by the galileo probe

atmospheric radiocarbon calibration to 45 000 yr b p late glacial fluctuations and cosmogenic isotope production more than 250 carbon 14 accelerator mass spectrometry dates of terrestrial macrofossils from annually laminated sediments from lake suigetsu japan provide a first atmospheric calibration for almost the total range of the radiocarbon method 45 000 years before the present the results confirm the recently revised floating german pine chronology and are consistent with data from european and marine varved sediments and combined uranium thorium and carbon 14 dating of corals up to the last glacial maximum the data during the glacial show large fluctuations in the atmospheric carbon 14 content related to changes in global environment and in cosmogenic isotope production

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

iceberg discharges into the north atlantic on millennial time scales during the last glaciation high resolution studies of north atlantic deep sea cores demonstrate that prominent increases in iceberg calving recurred at intervals of 2000 to 3000 years much more frequently than the 7000 to 10 000 year pacing of massive ice discharges associated with heinrich events the calving cycles correlate with warm cold oscillations called dansgaard oeschger events in greenland ice cores each cycle records synchronous discharges of ice from different sources and the cycles are decoupled from sea surface temperatures these findings point to a mechanism operating within the atmosphere that caused rapid oscillations in air temperatures above greenland and in calving from more than one ice sheet

computer simulations of jupiter s deep internal dynamics help interpret what juno sees we describe computer simulations of thermal convection and magnetic field generation in jupiter s deep interior that is its convective dynamo results from three different simulations highlight the importance of including the dynamics in the very deep interior although much of the convection and field generation seems to be confined to the upper part of the interior a long debated question is to what depth do jupiter s zonal winds extend below its surface our simulations suggest that if global latitudinally banded patterns in jupiter s near surface magnetic and gravity fields were detected by juno nasa s orbiting spacecraft at jupiter bolton s et al 2017 science 356 821 825 they would provide evidence for jupiter s zonal winds extending deep below the surface one of our simulations has also maintained for a couple simulated years a deep axisymmetric inertial wave with properties at the surface that depend on the size of the model s small rocky core if such a wave was detected on jupiter s surface its latitudes and oscillation frequency would provide evidence for the existence and size of jupiter s rocky core

millennial scale deep water oscillations reflections of the north atlantic in the deep pacific from 10 to 60 ka northeast pacific benthic foraminiferal 18o and 13 reveal repeated millennial scale events of strong deep sea ventilation associated with nutrient depletion and or high gas exchange during stadial cool high ice volume episodes from 10 to 60 ka opposite the pattern in the deep north atlantic two climate mechanisms may explain this pattern north pacific surface waters chilled by atmospheric transmission from a cold north atlantic and made saltier by reduced freshwater vapor transports could have ventilated the deep pacific from above alternatively faster turnover of pacific bottom and mid depth waters driven by southern ocean winds may have compensated for suppressed north atlantic deep water production during stadial intervals during the younger dryas event 11 6 13 0 cal ka ventilation of the deep ne pacific 2700 m lagged that in the santa barbara basin 450 m by 500 years suggesting that the ne pacific was first ventilated at intermediate depth from above and then at greater depth from below this apparent lag may reflect the adjustment time of global thermohaline circulation

latest quaternary north pacific surface water responses imply atmosphere driven climate instability a full sequence of brief interstadials dansgaard oeschger d o cycles are recorded from 60 to 25 ka in santa barbara basin california ocean drilling program hole 893a by planktonic foraminiferal isotopic and assemblage changes at unparalleled high resolution for the oceans synchronous climatic response between north pacific surface waters and the greenland ice sheet during d o cycling is strongly indicated by remarkable similarities in speed magnitude and character of rapid oceanic and atmospheric reorganizations inferred sea surface temperature warmings of as much as 5 c within a few decades and brief warming overshoots of as much as 3 c suggest involvement of an atmospheric amplification top down in situ atmospheric warming of the ocean is implied by differential responses partial decoupling in the changes recorded in surface and thermoclinal waters

patterns and causes of millennial scale climate change in the pacific northwest during marine isotope stages 2 and 3 abstract a high resolution pollen record from fargher lake washington shows a series of millennial scale changes in vegetation and climate during marine isotope stages mis 3 and 2 a comparison of fargher lake with pollen records from little lake oregon and carp lake washington reveals regional patterns of change during the early part of mis 3 ca 60 000 45 000 cal yr bp fargher and carp lakes indicate transitions between open and closed vegetation and cold dry and warm wet conditions between 45 000 and 27 500 cal yr bp all three records show shifts between low and high elevation taxa that indicate a series of temperature changes these temperature changes are similar to those in the santa barbara basin and may be explained by changes in the strength of the aleutian low during mis 2 27 500 14 000 cal yr bp shifts between wet and dry adapted taxa were most prominent at little lake there is also evidence for two minor warmings mis 2 climate variations do not correlate well with those in the santa barbara basin however precipitation changes in the pacific northwest during mis 2 correlate with evidence of ice sheet surges into the north atlantic and were probably related to variations in the strength and position of the glacial anticyclone and the jet stream

paleofire severity and vegetation change in the cascade range oregon usa paleoecological research has expanded our knowledge of the relationships between climate fire and vegetation fire can be a significant driver of forest composition and structure change but identifying and quantifying fire regimes has been elusive using high resolution charcoal analysis and pollen analysis we reconstructed a 13 200 year old fire and vegetation history from breitenbush lake oregon located in the central cascade range usa our objective was to examine if fire occurrence and severity may have been a driver of holocene forest composition change the data from this study suggests that while fire can create opportunities for successional process to occur fire events were not significant catalysts for forest change instead most major transitions at breitenbush lake occurred during prolonged fire free intervals our results reinforce the view that climate is the major control of vegetation composition change in the cascade range

icing the north atlantic there is debate over the causes of the large and abrupt climate changes that the north atlantic region has experienced in the past and may do in the future the driving forces of such changes might originate in the north atlantic itself or could be transmitted to the region from elsewhere new evidence on the extent and movement of the british ice sheet around the end of the last ice age supports the first contention and in particular implicates the advance and retreat of the laurentide ice sheet in causing some of the big climate jumps of the past

biogenic sedimentation beneath the california current system for the past 30 kyr and its paleoceanographic significance a north south transect of 17 cores was constructed along the eastern boundary of the california current system from 33 to 42 n to investigate the changes in biogenic sedimentation over the past 30 kyr percentages and mass accumulation rates of caco3 corg and biogenic opal were assembled at 500 to 1000 years sample to provide relatively high resolution time space maps reveal a complex pattern of changes that do not follow a simple glacial interglacial two mode model biogenic sedimentation shows responses that are sometimes time transgressive and sometimes coeval and most of the responses show more consistency within a limited geographic area than any temporal consistency reconstructed conditions during late oxygen isotope stage 3 were more like early holocene conditions than any other time during the last 30 kyr coastal upwelling and productivity during oxygen isotope stage 3 were relatively strong along the central california margin but were weak along the northern california margin precipitation increased during the last glacial interval in the central california region and the waters of the southern california margin had relatively low productivity productivity on the southern oregon margin was relatively low at the beginning of the last glacial interval but by about 20 ka productivity in this area significantly increased this change suggests that the center of the divergence of the west wind drift shifted south at this time the end of the last glacial interval was characterized by increased productivity in the southern california margin and increased upwelling along the central california margin but upwelling remained weak along the northern california margin a sudden 300 years decrease in caco3 corg and biogenic opal occurred at 13 ka the changes suggest a major reorientation of the atmospheric circulation in the north pacific and western north america and the establishment of a strong seasonality in the central california region a carbonate preservation event occurred at 10 ka that appears to reflect the uptake of co2 by the terrestrial biosphere as the northern latitudes were reforested following retreat of the glaciers the holocene has been a period of relatively high productivity in the southern california margin relatively strong coastal upwelling along the central california margin relatively weak upwelling along the northern california margin and the northward migration of the divergence zone of the west wind drift

jupiter s interior and deep atmosphere the initial pole to pole passes with the juno spacecraft on 27 august 2016 the juno spacecraft acquired science observations of jupiter passing less than 5000 kilometers above the equatorial cloud tops images of jupiter s poles show a chaotic scene unlike saturn s poles microwave sounding reveals weather features at pressures deeper than 100 bars dominated by an ammonia rich narrow low latitude plume resembling a deeper wider version of earth s hadley cell near infrared mapping reveals the relative humidity within prominent downwelling regions juno s measured gravity field differs substantially from the last available estimate and is one order of magnitude more precise this has implications for the distribution of heavy elements in the interior including the existence and mass of jupiter s core the observed magnetic field exhibits smaller spatial variations than expected indicative of a rich harmonic content

tecolote volcano pinacate volcanic field sonora mexico a case of highly explosive basaltic volcanism and shifting eruptive styles abstract explosive basaltic eruptions have been documented in monogenetic volcanic fields and recognizing the scales of their explosivity is important for understanding the full range of basaltic volcanism here we reconstruct one of the youngest eruptions in the pinacate volcanic field sonora mexico and estimate the volumes of the lava flows scoria cone and tephra units the source vent of the eruption is tecolote volcano 27 6 ka 40ar 39ar there were two distinct episodes of tephra production tephra unit 1 t1 followed by tephra unit 2 t2 t1 and t2 show different dispersal patterns with t1 dispersed in an approximately circular pattern and t2 dispersed oblately trending se and nw of the vent based on column height reconstructions and deposit characteristics the t1 producing eruption was subplinian 15 18 km plume with a calculated mass eruption rate ranging between 1 0 0 6 107 kg s and 2 2 1 2 107 kg s and corresponding durations between 79 54 min and 38 26 min respectively the t2 producing eruption was violent strombolian 11 km plume with a calculated mass eruption rate of 3 2 1 4 106 kg s and resulting duration of 193 78 min in addition to the two tephra units tecolote volcano produced seven morphologically distinct lava flows the majority of lava volume production occurred before and partly contemporaneously with tephra production and five small volume lava flows were emplaced after pyroclastic activity terminated indicating shifting and simultaneous eruptive styles of the total 0 23 km3 dense rock equivalent dre erupted volume the lava flows constitute the majority 0 17 km3 dre with 0 041 km3 dre volume for the cone and a combined 0 026 0 005 km3 dre volume for the two tephra units the geochemistry of the samples is consistent with that determined for other pinacate rocks which show a trend most similar to that of ocean island basalts and appears characteristically similar to other volcanic fields of the basin and range province

sensitivity of northern hemisphere air temperatures and snow expansion to north pacific sea surface temperatures in the goddard institute for space studies general circulation model circum pacific marine and terrestrial records indicate a series of temperature inferred oscillations during the late glacial while many previous studies have probed the role of the north atlantic in these oscillations we test the sensitivity of the northern hemisphere air temperatures to north pacific sea surface temperature sst oscillation in the goddard institute for space studies general circulation model the effect of a colder north pacific is to cool air temperatures over north america as well as parts of europe and asia the colder ssts result in a large hemispheric response due to the loss of water vapor as a greenhouse gas the large sensitivity of the northern hemisphere to a north pacific sst change has implications for the ice age climate as well as the late glacial interval the results of this experiment provide a rapid mechanism for widespread cooling which has not been previously addressed

the paleoenvironment of the olympia beds based on fossil beetles from discovery park seattle washington u s a abstract two fossil insect assemblages with ages of 17 959 and 19 786 cal bp are reported from cross laminated silts and sands within the olympia beds at magnolia bluff discovery park seattle washington n 47 39 w 122 25 the silts accumulated during mis 2 at a time when the puget lobe of the cordilleran ice sheet was advancing southward eventually the olympia beds were buried sequentially by lacustrine beds outwash sands and gravels and finally till the depositional environment based on paleoecology and sedimentary facies was a floodplain of a large braided river the fossils are disarticulated skeletal parts representing a diverse fauna of 132 beetle species all extant the habitats represented by fossils include sparsely vegetated sand and gravel bars opisthius richardsoni open muddy areas elaphrus californicus and vegetation shaded banks elaphrus clairvillei and elaphrus purpurans outside of the floodplain the habitat was grassland carabus taedatus with occasional stands of coniferous trees indicated by scolytids bark beetles large mammals probably used the river as a watering hole based on the abundance of dung feeding aphodiinae scarabs and staphylinid beetles tachinus most of the beetle species have modern geographic ranges which include northern washington state notably however species characteristic of the temperate rainforest of the pacific northwest are absent for the older of the two fossil assemblages mean summer temperature is estimated to be 17 c or similar to seattle today the climate was more continental and winters would have been colder than at seattle today the occurrence of the northern species pelophila borealis and olophrum boreale in the younger of the two assemblages indicates a colder climate estimated to represent a lowering of mean summer temperature by 1 2 c the climatic cooling is possibly associated with the advance of the puget lobe both pollen and fossil beetle evidence are in agreement that there was less available moisture possibly one half of today s precipitation palynologists have referred to the mis 2 vegetation as tundra cold steppe or subarctic parkland none of the discovery park fossils are obligate tundra species and because the majority of taxa have ranges which overlap in northern washington state today we prefer to use the term prairie for the temperate to cold temperate mis 2 grassland

jupiter new estimates of the mean zonal flow at the cloud level abstract previous estimates of the mean zonal flow on jupiter from voyager images by ingersoll et al a p ingersoll r f beebe j l mitchell g w garneau g m yagi and j p mueller 1981 j geophys res 86 8733 8743 and by limaye et al s s limaye h e revercomb l a sromovsky r j krauss v e suomi s a collins and c c avis 1982 j atmos sci 39 1413 1432 showed good agreement in the locations of the easterly and westerly jets but differed somewhat in magnitude recent measurements of the high speed jet located near 24 north plane topographic latitude by t maxworthy 1984 planet space sci 32 1053 1058 from high spatial and temporal resolution voyager images indicate that both ingersoll et al and limaye et al underestimated the magnitude of the jet by more than 30 40 msec 1 in an attempt to examine the differences in the magnitude of the jovian jets determined from voyager 1 and 2 images a new approach to determine the zonal mean east west component of motion was investigated the new technique based on simple digital pattern matching approach and applied on pairs of mapped images cylindrical mosaics yields a profile of the mean zonal component that reproduces the exact locations of the easterly and westerly jets between 60 latitude not only do the jet magnitudes but also the wings of the jets agree remarkably well from mosaic pair to pair further the latitudinal resolution is five midlatitudes to eight times equatorial greater than previous results results have been obtained for all of the voyager 1 and 2 cylindrical mosaics the correlation coefficient between voyager 1 and voyager 2 average mean zonal flow between 60 latitude determined from violet filter mosaics is 0 998 a slight latitude offset possibly due to navigation errors is detectable 0 2 latitude average in the voyager 1 data independent cloud motion measurements in two high resolution image pairs orange and violet acquired from voyager 1 cameras agree well with the average mean zonal flow for the fastest jovian jet at 23 8 n latitude comparison with maxworthy s 1984 results suggests longitudinal variations in cloud motions approaching about 20 msec 1 in particular the jet magnitude is about 163 7 rms msec 1 which compares well with 182 10 msec 1 reported by maxworthy there is excellent agreement in the location of the peak magnitude as well as its shape the time average voyager 2 mean zonal flow profile with latitude is presented in a table

mid infrared mapping of jupiter s temperatures aerosol opacity and chemical distributions with irtf texes abstract global maps of jupiter s atmospheric temperatures gaseous composition and aerosol opacity are derived from a programme of 5 20 m mid infrared spectroscopic observations using the texas echelon cross echelle spectrograph texes on nasa s infrared telescope facility irtf image cubes from december 2014 in eight spectral channels with spectral resolutions of r 2000 12 000 and spatial resolutions of 2 4 latitude are inverted to generate 3d maps of tropospheric and stratospheric temperatures 2d maps of upper tropospheric aerosols phosphine and ammonia and 2d maps of stratospheric ethane and acetylene the results are compared to a re analysis of cassini composite infrared spectrometer cirs observations acquired during cassini s closest approach to jupiter in december 2000 demonstrating that this new archive of ground based mapping spectroscopy can match and surpass the quality of previous investigations and will permit future studies of jupiter s evolving atmosphere the visibility of cool zones and warm belts varies from channel to channel suggesting complex vertical variations from the radiatively controlled upper troposphere to the convective mid troposphere we identify mid infrared signatures of jupiter s 5 m hotspots via simultaneous m n and q band observations which are interpreted as temperature and ammonia variations in the northern equatorial zone and on the edge of the north equatorial belt neb equatorial plumes enriched in nh3 gas are located south east of nh3 desiccated hotspots on the edge of the neb comparison of the hotspot locations in several channels across the 5 20 m range indicate that these anomalous regions tilt westward with altitude aerosols and ph3 are both enriched at the equator but are not co located with the nh3 plumes the equatorial temperature minimum and ph3 aerosol maxima have varied in amplitude over time possibly as a result of periodic equatorial brightenings and the fresh updrafts of disequilibrium material temperate mid latitudes display a correlation between mid ir aerosol opacity and the white albedo features in visible light i e zones we find hemispheric asymmetries in the distribution of tropospheric ph3 stratospheric hydrocarbons and the 2d wind field estimated via the thermal wind equation that suggest a differing efficiency of mechanical forcing e g vertical mixing and wave propagation between the two hemispheres that we argue is driven by dynamics rather than jupiter s small seasonal cycle jupiter s stratosphere is notably warmer at northern mid latitudes than in the south in both 2000 and 2014 although the latter can be largely attributed to strong thermal wave activity near 30 n that dominates the 2014 stratospheric maps and may be responsible for elevated c2h2 in the northern hemisphere a vertically variable pattern of temperature and windshear minima and maxima associated with jupiter s quasi quadrennial oscillation qqo is observed at the equator in both datasets although the contrasts were more subdued in 2014 large scale equator to pole gradients in ethane and acetylene are superimposed on top of the mid latitude mechanically driven maxima with c2h2 decreasing from equator to pole and c2h6 showing a polar enhancement consistent with a radiatively controlled circulation from low to high latitudes cold polar vortices beyond 60 latitude can be identified in the upper tropospheric and lower stratospheric temperature maps suggesting enhanced radiative cooling from polar aerosols finally compositional mapping of the great red spot confirms the local enhancements in ph3 and aerosols the north south asymmetry in nh3 gas and the presence of a warm southern periphery that have been noted by previous authors

the vertical structure of jupiter s equatorial zonal wind above the cloud deck derived using mesoscale gravity waves 1 data from the galileo probe collected during its descent into jupiter s atmosphere is used to obtain a vertical profile of the zonal wind from 0 5 bar upper troposphere to 0 1 bar lower thermosphere at the probe entry site this is accomplished by constructing a map of gravity wave lomb scargle periodograms as a function of altitude the profile obtained from the map indicates that the wind speed above the visible cloud deck increases with height to 150 m s 1 and then levels off at this value over a broad altitude range the location of the turbopause as a region of wide wave spectrum is also identified from the map in addition a cross equatorial oscillation of a jet which has previously been linked to the qqo in the stratosphere is suggested by the profile

correlation of late pleistocene glaciation in the western united states with north atlantic heinrich events a survey of the chronology of late pleistocene glaciers in the western united states indicates a record of glacier advances during the last glaciation which is more variable than that predicted by orbital forcing numerical dating of late pleistocene deposits from the puget lobe of the cordilleran ice sheet and alpine glaciers and ice caps in the rocky mountains and cascade range suggests that advances and retreats of these glaciers were in phase with episodes of growth and collapse of the laurentide ice sheet associated with the north atlantic heinrich events specifically the existing chronologies indicate that these glaciers were advancing to their terminal areas up to several thousand years before a heinrich event and retreated shortly thereafter because midlatitude glaciers respond relatively rapidly to climate change this complex record of glacial fluctuations suggests mechanisms of climate forcing in western north america that are in some way tied to heinrich events one possible mechanism involves southerly and northerly displacement of the jet stream across the western united states in response to growth and collapse of the laurentide ice sheet

dynamics of jupiter s equatorial region at cloud top level from cassini and hst images abstract we present a study of the equatorial region of jupiter between latitudes 15 s and 15 n based on cassini iss images obtained during the jupiter flyby at the end of 2000 and hst images acquired in may and july 2008 we examine the structure of the zonal wind profile and report the detection of significant longitudinal variations in the intensity of the 6 n eastward jet up to 60 m s 1 in cassini and hst observations these longitudinal variations are in the hst case associated with different cloud morphology photometric and radiative transfer analysis of the cloud features used as tracers in hst images show that at most there is only a small height difference no larger than 0 5 1 scale heights between the slow 100 m s 1 and fast 150 m s 1 moving features this suggests that speed variability at 6 n is not dominated by vertical wind shears but instead we propose that rossby wave activity is the responsible for the zonal variability removing this variability we find that jupiter s equatorial jet is actually symmetric relative to equator with two peaks of 140 150 m s 1 located at latitudes 6 n and 6 s and at a similar pressure level we also study the local dynamics of particular equatorial features such as several dark projections associated with 5 m hot spots and a large long lived feature called the white spot ws located at 6 s convergent flow at the dark projections appears to be a characteristic which depends on the particular morphology and has only been detected in some cases the internal flow field in the white spot indicates that it is a weakly rotating quasi equatorial anticyclone relative to the ambient meridionally sheared flow

earth based radio tracking of the galileo probe for jupiter wind estimation although the galileo probe was designed to communicate only to the orbiter the probe radio signal was detected at two earth based radio observatories where the signal was a billion times weaker the measured signal frequency was used to derive a vertical profile of the jovian zonal wind speed due to the mission geometry the earth based wind estimates are less sensitive to descent trajectory errors than estimates based on probe orbiter doppler measurements the two estimates of wind profiles agree qualitatively both show high wind speeds at all depths sampled

a study of the stability of jovian zonal winds from hst images 1995 2000 abstract we present a five year study of the temporal stability of jupiter s zonal wind velocity profile at cloud level based on hubble space telescope images obtained from 1995 to 2000 we used the correlation of east west albedo scans in pairs of images separated by one jovian rotation to retrieve the zonal winds the resolution in the hst images ranged from 140 to 190 km pixel 1 independent measurements of the motions of individual cloud tracers were used to control the above profiles three wavelengths were used in this analysis 410 nm violet continuum 892 nm methane absorption band and 953 nm red continuum our study indicates that globally jupiter s zonal flow did not change during this five year interval and it does not depend on the observed wavelengths when comparing our mean profile with that obtained 16 years ago using voyager data we find a reasonable agreement we note however a small shift in the latitude of the jets poleward of latitude 30 probably due to image navigation uncertainties however true changes in the intensity of the jets at 24 n and 32 n are found results also indicate that the 7 s jet has remained stable since the voyager era in addition we extend in this paper our previous study of the 24 n with new data from year 2000 the new data confirm the jet s stability during the 1995 2000 period finally we present the average profile for this period including error estimation in a table that extends the latitudinal coverage of limaye s 1986 icarus 65 335 352 voyager profile up to latitudes 68 s and 77 n

brief interstadial events in the santa barbara basin ne pacific during the past 60 kyr the instability of the northern hemisphere glacial climate over the past 100 kyr has been revealed by at least 20 brief warm interstadial episodes called dansgaard oeschger events recorded in greenland ice cores1 3 and in north atlantic sedimentary records4 5 a few of these events have been recognized elsewhere6 8 here we describe a record of ocean oxygenation and circulation from the santa barbara basin in the northeast pacific ocean which correlates well with the greenland ice core records we see 19 of the 20 dansgaard oeschger events in the form of laminated sediments deposited under anoxic conditions and we can correlate at least 16 of these with the 17 ice core interstadials of the past 60 kyr thus these short term events were not restricted to the north atlantic region the events had substantial ecological and oceanographic effects in the santa barbara basin including changes in benthic faunal populations and in the age and composition of bottom waters similar ventilation changes have been seen in the gulf of california9 10 suggesting that these changes may have been widespread and synchronous along the northeast pacific margin these results suggest sensitivity of broad areas of the ocean atmosphere cryosphere system to short term climate change

paleoclimate simulations for north america over the past 21 000 years features of the simulated climate and comparisons with paleoenvironmental data maps of upper level and surface winds and of surface temperature and precipitation illustrate the results of a sequence of global paleoclimatic simulations spanning the past 21 000 years for north america we review a the large scale features of circulation temperature and precipitation that appear in the simulations from the ncar community climate model version 1 ccm 1 b the implications of the simulated climate for the past continental scale distributions of three plant taxa picea spp pseudotsuga menziesii and artemisia tridentata which are broadly representative of the vegetation across the continent and c the potential explanations in terms of atmospheric circulation or surface energy and water balance processes for mismatches between the simulations and observations most of the broad scale features of previous paleoclimatic simulations with the ncar ccm 0 for north america are present in the current simulations many of the elements of a conceptual model based on previous climate simulations that describes the controls of paleoclimatic variations across north america during the past 21 000 years are found in simulations reviewed here these include 1 displacement of the jet stream by the laurentide ice sheet to the south of its present position in both winter and summer 2 generation of a glacial anticyclone over the ice sheet at the lgm and the consequent induction of large scale sinking motions induced over eastern north america 3 changes in the strength of surface atmospheric circulation features through time including weakening of the aleutian low in winter and strengthening of the eastern pacific and bermuda high pressure systems in summer as the ice sheet decreased in size 4 development of a heat low at the surface and a strengthened ridge in the upper atmosphere over the continent at the time of the maximum summer insolation anomaly 5 increases in summer temperature earlier in regions remote from the ice sheet these increases appear earlier in the present ccm 1 simulations than in the previous ccm 0 ones however and 6 continuation of negative winter temperature anomalies into the middle holocene in general simulated surface conditions that are discordant with paleoenvironmental observations can be attributed to the simulation of particular atmospheric circulation patterns e g those that suppress precipitation or advect warm air into a region with these mismatches amplified in beringia and the southeastern united states by surface energy and water balance processes

late quaternary vegetation near battle ground lake southern puget trough washington pollen and plant macrofossil records from battle ground lake along with published data are used to reconstruct the late quaternary vegetation history of the nonglaciated southern puget trough coinciding with the end of the evans creek stade circa 20 000 17 000 yr b p of fraser glaciation gramineae artemisia herbs and picea cf engelmannii grew in a parkland tundra around battle ground this assemblage recorded throughout the southern puget trough implies cold relatively dry conditions similar to subalpine environments east of the cascade range the presence of pseudotsuga picea sitchensis and alnus rubra as macrofossils suggests a slight interstadial warming between 17 000 and 15 000 yr b p cool humid conditions prevailed during the vashon stade when south of the cordilleran ice sheet open forest or parkland featured mesophytic subalpine taxa at battle ground lake temperate conifers were part of forest communities circa 11 200 yr b p but elsewhere they were present as early as 12 500 yr b p from 10 000 to 4500 yr b p pseudotsuga quercus savannah spread into the battle ground area offering evidence for summer drought more severe than today pseudotsuga and thuja forest was established in the late holocene with the introduction of the modern humid climate consideration of all the pollen data from the southern puget trough and the available radiometric chronology suggests that postglacial migration of most lowland conifers into the puget trough was rapid and not necessarily from southern refugia

late quaternary climatic controls on erosion rates and geomorphic processes in western oregon usa climate regulation of erosion in unglaciated landscapes remains difficult to decipher while climate may disrupt process feedbacks that would otherwise steer landscapes toward steady erosion sediment transport processes tend to erase past climate landforms and thus bias landscape evolution interpretations here we couple a 50 k y paleoenvironmental record with 24 10be derived paleo erosion rates from a 63 m thick sediment archive in the unglaciated soil mantled oregon coast range our results span the forested marine oxygen isotope stage mis 3 50 29 ka the subalpine mis 2 29 14 ka and the forested mis 1 14 ka to present from 46 ka through 28 5 ka erosion rates increased from 0 06 mm yr 1 to 0 23 mm yr 1 coincident with declining temperatures mean mis 2 erosion rates remained at 0 21 mm yr 1 and declined with increasing mis 1 temperatures to the modern mean rate of 0 08 mm yr 1 paleoclimate reconstructions and a frost weathering model suggest periglacial processes were vigorous between 35 and 17 ka while steady erosion is often assumed our results suggest that climate strongly modulates soil production and transport on glacial interglacial time scales by applying a cosmogenic paleo erosion model to evaluate 10be concentrations in our sedimentary archive we demonstrate that the depth of soil mixing which is climate dependent controls the lag time required for cosmogenic erosion rates to track actual values our results challenge the widely held assumption that climate has minimal impact on erosion rates in unglaciated midlatitude terrain which invites reconsideration of the extent to which past climate regimes manifest in modern landscapes

jupiter s atmospheric jet streams extend thousands of kilometres deep the depth to which jupiter s observed east west jet streams extend has been a long standing question resolving this puzzle has been a primary goal for the juno spacecraft which has been in orbit around the gas giant since july 2016 juno s gravitational measurements have revealed that jupiter s gravitational field is north south asymmetric which is a signature of the planet s atmospheric and interior flows here we report that the measured odd gravitational harmonics j 3 j 5 j 7 and j 9 indicate that the observed jet streams as they appear at the cloud level extend down to depths of thousands of kilometres beneath the cloud level probably to the region of magnetic dissipation at a depth of about 3 000 kilometres by inverting the measured gravity values into a wind field we calculate the most likely vertical profile of the deep atmospheric and interior flow and the latitudinal dependence of its depth furthermore the even gravity harmonics j 8 and j 10 resulting from this flow profile also match the measurements when taking into account the contribution of the interior structure these results indicate that the mass of the dynamical atmosphere is about one per cent of jupiter s total mass

late glacial vegetation and climate change in western oregon abstract pollen records from two sites in western oregon provide information on late glacial variations in vegetation and climate and on the extent and character of younger dryas cooling in the pacific northwest a subalpine forest was present at little lake central coast range between 15 700 and 14 850 cal yr b p a warm period between 14 850 and 14 500 cal yr b p is suggested by an increase inpseudotsugapollen and charcoal the recurrence of subalpine forest at 14 500 cal yr b p implies a return to cool conditions another warming trend is evidenced by the reestablishment ofpseudotsugaforest at 14 250 cal yr b p increased haploxylonpinuspollen between 12 400 and 11 000 cal yr b p indicates cooler winters than before after 11 000 cal yr b p warm dry conditions are implied by the expansion ofpseudotsuga a subalpine parkland occupied gordon lake western cascade range until 14 500 cal yr b p when it was replaced during a warming trend by a montane forest a rise inpinuspollen from 12 800 to 11 000 cal yr b p suggests increased summer aridity pseudotsugadominated the vegetation after 11 000 cal yr b p other records from the pacific northwest show an expansion ofpinusfrom ca 13 000 to 11 000 cal yr b p this expansion may be a response either to submillennial climate changes of younger dryas age or to millennial scale climatic variations

wind speeds measured in the deep jovian atmosphere by the galileo probe accelerometers the atmosphere of jupiter has a complex circulation which until recently has been observable only at the cloud tops1 2 the mechanisms driving the winds and the nature of the interior circulation remained unknown3 recent analyses4 5 6 of the radio signal from the galileo probe obtained during its descent into the jovian atmosphere have suggested a vigorous interior circulation below the 4 bar level here we report an independent measurement of the winds below the cloud tops making use of the data obtained by the two accelerometers on the descending probe we find evidence for two distinct wind regimes in general agreement with the doppler radio measurements a region of wind shear between 1 and 4 bar where the wind speed increases dramatically with depth and then a region of constant high velocity winds down to at least the 17 bar level

a 7600 yr vegetation and fire history from anthony lake northeastern oregon usa with linkages to modern synoptic climate patterns we used pollen and high resolution charcoal analysis of lake sediment to reconstruct a 7600 yr vegetation and fire history from anthony lake located in the blue mountains of northeastern oregon from 7300 to 6300 cal yr bp the forest was composed primarily of populus and fire was common indicating warm dry conditions from 6300 to 3000 cal yr bp populus declined as pinus and picea increased in abundance and fire became less frequent suggesting a shift to cooler wetter conditions from 3000 cal yr bp to present modern day forests composed of pinus and abies developed and from 1650 cal yr bp to present fires increased we utilized the modern climate analogue approach to explain the potential synoptic climatological processes associated with regional fire the results indicate that years with high fire occurrence experience positive 500 mb height anomalies centered over the great basin with anomalous southerly component of flow delivering dry air into the region and with associated sinking motions to further suppress precipitation it is possible that such conditions became more common over the last 1650 cal yr bp supporting an increase in fire despite the shift to more mesic conditions

reconstruction of last glacial to early holocene monsoon variability from relict lake sediments of the higher central himalaya uttrakhand india abstract proglacial lake sediments at goting in the higher central himalaya were analyzed to reconstruct the summer monsoon variability during the last glacial to early holocene sedimentary structures high resolution mineral magnetic and geochemical data suggest that the lacustrine environment experienced fluctuating monsoonal conditions optically stimulated luminescence osl dating indicates that the lake sedimentation occurred before 25 ka and continued after 13 ka during this period goting basin witnessed moderate to strengthened monsoon conditions around 25 ka 23 5 ka 22 5 ka 22 ka 18 ka 17 ka 16 5 ka and after14 5 13 ka the last glacial phase ended with the deposition of outwash gravel dated at 11 ka indicating glacial retreat and the onset of holocene condition additionally centennial scale fluctuations between 16 5 ka and 12 7 ka in the magnetic and geochemical data are seen a close correspondence at the millennial scale between our data and that of continental and marine records from the indian sub continent suggests that goting basin responded to periods of strengthened monsoon during the last glacial to early holocene we attribute the millennial scale monsoon variability to climatic instability in higher northern latitudes however centennial scale abrupt changes are attributed to the result of albedo changes on the himalaya and tibetan plateau

modelling teleconnections between the north atlantic and north pacific during the younger dryas evidence for a cooling event synchronous with the younger dryas 12 000 calendar years before present has been found in the north pacific ocean north of 30 n in records of surface1 5 and subsurface water properties6 7 these changes may be related to a temporary shut down of north atlantic deep water formation and associated surface cooling over the north atlantic it has remained unclear however whether this north atlantic cooling was communicated to the north pacific ocean through the atmosphere or the ocean here we report results of a sensitivity experiment with a coupled ocean atmosphere general circulation model that support a primarily atmospheric forcing of north pacific climate variations changes in wind strongly affect coastal upwelling at the north american west coast and surface cooling by the atmosphere causes better ventilation of the thermocline waters of the northeast pacific this effect is amplified by oceanic progagation to the pacific of the signal arising from collapse of north atlantic deep water formation these teleconnections may also explain earlier north pacific and western north american millenial scale cooling events of a similar nature8 12

evidence for millennial scale climate change during marine isotope stages 2 and 3 at little lake western oregon u s a pollen and geochemical data from little lake western oregon suggest several patterns of millennial scale environmental change during marine isotope stage mis 2 14 100 27 600 cal yr b p and the latter part of mis 3 27 600 42 500 cal yr b p during mis 3 a series of transitions between warm and cold adapted taxa indicate that temperatures oscillated by ca 2 4 c every 1000 3000 yr highs and lows in summer insolation during mis 3 are generally associated with the warmest and coldest intervals warm periods at little lake correlate with warm sea surface temperatures in the santa barbara basin changes in the strength of the subtropical high and the jet stream may account for synchronous changes at the two sites during mis 2 shifts between mesic and xeric subalpine forests suggest changes in precipitation every 1000 3000 yr increases in tsuga heterophylla pollen at 25 000 and 22 000 cal yr b p imply brief warmings minimum summer insolation and maximum global ice volumes during mis 2 correspond to cold and dry conditions fluctuations in precipitation at little lake do not correlate with changes in the santa barbara basin and may be explained by variations in the strength of the glacial anticyclone and the position of the jet stream c 2001 university of washington

quantitative interpretation of fossil pollen spectra dissimilarity coefficients and the method of modern analogs abstract dissimilarity coefficients measure the difference between multivariate samples and provide a quantitative aid to the identification of modern analogs for fossil pollen samples how eight coefficients responded to differences among modern pollen samples from eastern north america was tested these coefficients represent three different classes 1 unweighted coefficients that are most strongly influenced by large valued pollen types 2 equal weight coefficients that weight all pollen types equally but can be too sensitive to variations among rare types and 3 signal0to noise coefficients that are intermediate in their weighting of pollen types the studies with modern pollen allowed definition of critical values for each coefficient which when not exceeded indicate that two pollen samples originate from the same vegetation region dissimilarity coefficients were used to compare modern and fossil pollen samples and modern samples so similar to fossil samples were found that most of three late quaternary pollen diagrams could be reconstructed by substituting modern samples for fossil samples when the coefficients indicated that the fossil spectra had no modern analogs then the reconstructed diagrams did not match all aspects of the originals no modern analogs existed for samples from before 9300 yr b p at kirchner marsh minnesota and from before 11 000 yr b p at wintergreen lake michigan but modern analogs existed for almost all holocene samples from these two sites and brandreth bog new york

climate and vegetation since the last interglacial mis 5e in a putative glacial refugium northern idaho usa abstract there are very few terrestrial sediment records from north america that contain a nearly continuous sequence spanning from the last interglacial period to the present we present stratigraphic records of pollen and several other proxies from a carex dominated wetland star meadows located 140 km south of the maximum extent of the cordilleran ice sheet and near the current southern extent of interior mesic forests in northern idaho many species in this region are disjunct by 160 km of arid steppe and dry forest from their more extensive distribution along the pacific northwest coast and may have survived in an interior refugium the chronology for the upper 251 cm was determined by six radiocarbon dates and one tephra deposit and the age of the remainder of the core 251 809 cm was estimated by correlation with specmap 18 o fluctuating water levels were inferred from alternating peat biogenic silica and aquatic pollen types during mis 5e the region was warmer and drier than today and was dominated by pinus likely pinus contorta mixed conifer forest surrounding a carex meadow a cool moist climate mis 5b 5d soon developed and the site was inundated with deep water pollen indicated wetland vegetation betula glandulosa typhaceae and salix developed around a lake with a pseudotsuga larix and picea forest on the surrounding slopes during mis 5a a warmer climate supported a pseudotsuga larix abies and picea forest on the surrounding hillsides and a carex dominated environment within a dry meadow from mis 4 to mis 3 a cool and wet pinus and picea forest predominated water levels rose enabling nuphar to persist within a perennial lake while a sedge fen established along the lake margin as climate transitioned into mis 2 a cooler and drier climate supported a pinus and picea subalpine parkland though water levels remained high enough to support nuphar during the last glacial maximum the sediment was mainly silt and clay with high artemisia and very poor pollen preservation glaciers descended to 500 m elevation above star meadows in adjacent drainages suggesting a periglacial environment occurred at the site lake level decreased through the pleistocene holocene transition ca 11 7 ka and the site returned to a sedge peatland surrounded by an open pinus forest the most striking vegetation change occurred in the middle to late holocene with the first occurrence and then later dominance of cupressaceae pollen most likely thuja plicata which is a dominant species in modern interior mesic forests the late holocene vegetation was uniquely mesic in the context of the last 120 000 years casting doubt on this region serving as a glacial refugium

humptulips revisited a revised interpretation of quaternary vegetation and climate of western washington usa abstract new pollen data from a 770 cm core of a mire at humptulips on the southwestern olympic peninsula 47 17 00 n 123 54 40 w and from a nearby deposit regarded as interglacial in age on the west fork of the humptulips river provide evidence for a reinterpretation of previous accounts of the quaternary vegetation and climate using a new age model the highly variable record at humptulips is here correlated with marine oxygen isotope stages ois 1 5a vegetation during ois 5a was pine dominated mixed woodland and tundra in ois 4 3 and 2 oscillations in pollen assemblages imply repeated intervals of mountain hemlock parkland and tundra pine as an indicator of openness is also abundant in these stages interstadial fluctuations in ois 3 reflect episodes of lowland western hemlock communities the earliest of the episodes is of infinite radiocarbon age and the latest dates to approximately 30 000 14 c yr b p parkland in ois 2 occurring after 24 600 until at least 18 440 14 c yr b p was replaced by transitional pine alder in ois 1 holocene which unlike any of the earlier stages conveys the development of modern lowland forest dominated by western hemlock pollen assemblages over the length of record imply that temperature and humidity at no time were as high as at present only in ois 3 do conditions approach those occurring in ois 1 during ois 2 3 and 4 when tree line apparently stood at the location of the site climate was colder and drier temperatures were depressed an estimated 5 c with precipitation close to 1000 mm compared with 2000 3000 mm at present atmospheric circulation during ois 2 appears to have been much controlled by the location of the laurentide ice sheet in the continental interior whereas under the current climatic regime beginning in the early holocene westerly air flow has dominated regulated by interplay between the north pacific high in summer and the wintertime aleutian low

forest or no forest implications of the vegetation record for climatic stability in western beringia during oxygen isotope stage 3 abstract two conflicting stratigraphic schemes describe the siberian karginskii interstade oxygen isotope stage 3 equivalent as having 1 relatively stable climate with environments more similar to the full glaciation or 2 variable climate with landscapes that more closely approximate contemporary ones new data from continuous lake cores and a nearly continuous section from western beringia wb suggest that both schemes are valid herb dominated communities possibly with isolated populations of larix characterized northern wb with only a slight shift from relatively warm to cool summers during the mid interstade in contrast herb and shrub tundra steppe forest tundra and modern larix forest occurred at various times in areas of southern wb suggesting greater climatic instability a thermal optimum is evident in the south during the mid interstade with modern vegetation in southeastern wb and larix forest tundra in the southwest variations in pinus pumila pollen indicate summer warm winter dry and summer warm winter wet conditions in southeastern wb these fluctuations contrast to other areas of wb where summers and probably winters were consistently arid although the interstade presents a unique interval within the late pleistocene paleodata and paleoclimatic models suggest that changes in marine conditions including sea level were likely key drivers in the regional climate history

olympia interstadial vegetation landscape history and paleoclimatic implications of a mid wisconsinan mis3 nonglacial sequence from southwest british columbia canada lithostratigraphic 14c and palynologic analyses of peat and silty peat at three nearby sites reveal a 25 000 year vegetation and climate history of the olympia interstade for the fraser lowland british columbia 300 km within the southern limit of the cordilleran ice sheet at lynn valley polypodiaceae fern spores and nonarboreal pollen dominate 47 8 14c ka bp reflecting unstable and cold landscapes a pinus poaceae zone follows representing pine parkland and cool dry climate fluctuating values of picea and tsuga mertensiana pollen at lynn and seymour valleys and port moody characterize most of the olympia interstade during local peat deposition in cyperaceae and myrica wetlands until about 26 7 14c ka bp under a cool and moist climate a brief pinus tsuga heterophylla zone at lynn valley 44 39 14c ka bp suggests a climatic optimum a poaceae artemisia assemblage and deposition of silty sand after 26 7 14c ka bp reflect cooling and drying after which a unique lycopodium assemblage at lynn valley

the relative utility of foraminifera and diatoms for reconstructing late holocene sea level change in north carolina usa abstract foraminifera and diatoms preserved in salt marsh sediments have been used to produce high resolution records of holocene relative sea level rsl change to determine which of these microfossil groups is most appropriate for this purpose we investigated their relative utility from salt marshes in north carolina usa regional scale transfer functions were developed using foraminifera diatoms and a combination of both multi proxy from three salt marshes oregon inlet currituck barrier island and pea island we evaluated each approach on the basis of transfer function performance foraminifera diatoms and multi proxy based transfer functions all demonstrated a strong relationship between observed and predicted elevations r 2 jack 0 74 and rmsep 210 pb and 14 c based chronology and we were able to reconcile this with tide gauge records

younger dryas environments and human adaptations on the west coast of the united states and baja california on the pacific coast of the united states and baja california the younger dryas was one component of dynamic late pleistocene and holocene environmental changes changing climate sea level rise and shifting shorelines created ecological challenges for ancient coastal peoples and daunting challenges for archaeologists searching for early coastal sites this paper reviews the evidence for ecological change in this west coast region including shoreline changes that may have submerged or destroyed archaeological sites from this time period examining the regional record of human occupation dating to the younger dryas well dated coastal sites are limited to california s northern channel islands and isla cedros off baja california a small number of fluted points found in coastal areas may also date to the younger dryas but their context and chronology is not well defined review of the implications of these two data sets considers whether the early but discontinuous younger dryas archaeological record from the west coast might result from a migration of maritime peoples from northeast asia into the americas

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

changes in jupiter s zonal velocity between 1979 and 2008 abstract we show that the peak velocity of jupiter s visible cloud level zonal winds near 24 n planetographic increased from 2000 to 2008 this increase was the only change in the zonal velocity from 2000 to 2008 for latitudes between 70 that was statistically significant and not obviously associated with visible weather we present the first automated retrieval of fast 130 m s 1 zonal velocities at 8 n planetographic latitude and show that some previous retrievals incorrectly found slower zonal winds because the eastward drift of the dark projections associated with 5 m hot spots fooled the retrieval algorithms we determined the zonal velocity in 2000 from cassini images from nasa s planetary data system using a global method similar to previous longitude shifting correlation methods used by others and a new local method based on the longitudinal average of the two dimensional velocity field we obtained global velocities from images acquired in may 2008 with the wide field planetary camera 2 wfpc2 on the hubble space telescope hst longer term variability of the zonal winds is based on comparisons with published velocities based on 1979 voyager 2 and 1995 1998 hst images fluctuations in the zonal wind speeds on the order of 10 m s 1 on timescales ranging from weeks to months were found in the 1979 voyager 2 and the 1995 1998 hst velocities in data separated by 10 h we find that the east west velocity uncertainty due to longitudinal fluctuations are nearly 10 m s 1 so velocity fluctuations of 10 m s 1 may occur on timescales that are even smaller than 10 h fluctuations across such a wide range of timescales limit the accuracy of zonal wind measurements the concept of an average zonal velocity may be ill posed and defining a temporal mean zonal velocity as the average of several zonal velocity fields spanning months or years may not be physically meaningful at 8 n we use our global method to find peak zonal velocities of 110 m s 1 in 2000 and 130 m s 1 in 2008 zonal velocities from 2000 cassini data produced by our local and global methods agree everywhere except in the vicinity of 8 n there the local algorithm shows that the east west velocity has large variations in longitude vast regions exceed 140 m s 1 our global algorithm and all of the velocity extraction algorithms used in previously published studies found the east west drift velocities of the visible dark projections rather than the true zonal velocity at the visible cloud level therefore the apparent increase in zonal winds between 2000 and 2008 at 8 n is not a true change in zonal velocity at 7 3 n the galileo probe found zonal velocities of 170 m s 1 at the 3 bar level if the true zonal velocity at the visible cloud level at this latitude is 140 m s 1 rather than 105 m s 1 then the vertical zonal wind shear is much less than the currently accepted value

late quaternary climatic and oceanographic changes in the northeast pacific as recorded by dinoflagellate cysts from guaymas basin gulf of california mexico a high resolution record of organic walled dinoflagellate cyst production in guaymas basin gulf of california mexico reveals a complex paleoceanographic history over the last 40 ka guaymas basin is an excellent location to perform high resolution studies of changes in late quaternary climate and paleo productivity because it is characterized by high primary productivity high sedimentation rates and low oxygen bottom waters these factors contribute to the deposition and preservation of laminated sediments throughout large portions of the core md02 2515 in this study we document dinoflagellate cyst production at a centennial to millennial scale throughout the late quaternary based on the cyst assemblages three dinoflagellate cyst zones were established and roughly correspond to marine isotope stages miss 1 to 3 miss 1 and 3 are dominated by cysts of heterotrophic dinoflagellates whereas mis 2 is characterized by enhanced variability and a greater proportion of cysts produced by autotrophic taxa the most dominant dinoflagellate cyst taxa found throughout the core were brigantedinium spp and operculodinium centrocarpum dansgaard oeschger event 8 is observed in the dinoflagellate cyst record where it is characterized by an increase in warm taxa such as spiniferites pachydermus other intervals of interest are the younger dryas where warmer conditions are recorded and the holocene which is characterized by the consistent presence of tropical species stelladinium reidii tuberculodinidum vancampoae bitectatodinium spongium and an increase in quinquecuspis concreta changes in cyst assemblages concentrations and species diversity along with geochemical data reflect major orbital to millennial scale climatic and oceanographic changes reference price a m k n mertens v pospelova t f pedersen and r s ganeshram 2013 late quaternary climatic and oceanographic changes in the northeast pacific as recorded by dinoflagellate cysts from guaymas basin gulf of california mexico paleoceanography 28 doi 10 1002 palo 20019

a record of late quaternary vegetation from davis lake southern puget lowland washington abstract pollen and macrofossil analyses of a core spanning 26 000 yr from davis lake reveal late pleistocene and holocene vegetational patterns in the puget lowland the core ranges lithologically from a basal inorganic clay to a detritus gyttja to an upper fibrous peat and includes eight tephra units the late pleistocene pollen sequence records two intervals of tundra parkland vegetation the earlier of these has high percentages of picea gramineae and artemisia pollen and represents the vegetation during the evans creek stade fraser glaciation ca 25 000 17 000 yr b p the later parkland interval is dominated by picea tsuga mertensiana and gramineae it corresponds to the maximum ice advance in the puget lowland during the vashon stade fraser glaciation ca 14 000 yr b p an increase in pinus ontorta pollen between the two tundra parkland intervals suggests a temporary rise in treeline during an unnamed interstade after 13 500 yr b p a mixed woodland of subalpine and lowland conifers grew at davis lake during a period of rapid climatic amelioration in the early holocene the prolonged expansion of pseudotsuga and alnus woodland suggests dry temperate conditions similar to those of present rainshadow sites in the puget lowland more mesic forests of tsuga eterophylla thuja plicata and pseudotsuga similar to present lowland vegetation appeared in the late holocene ca 5500 yr b p

late quaternary vegetation and climate history near little lake central coast range oregon pollen and plant macrofossils recovered from little lake oregon provide the first record of late quaternary climate and vegetation changes in oregon9s central coast range the pollen data suggest that the period from ca 42 000 to 24 770 yr b p featured an open forest of western white pine western hemlock and fir the inferred climate was cooler and wetter than today the full glacial period was characterized by a parkland of spruce lodgepole pine and mountain hemlock which suggests that the climate was colder and possibly drier than today the oregon coast range was not a glacial refugium for temperate conifers as has been proposed by 16 000 yr b p the pollen and plant macrofossil data suggest the development of a montane forest composed of pine fir western hemlock and mountain hemlock temperate taxa were present in the vegetation at 13 500 yr b p during a period of climatic amelioration a reversal in this warming trend may have occurred between 11 000 and 10 500 yr b p when pine western and mountain hemlock and spruce were slightly more abundant early holocene forests featured douglas fir red alder and bracken fern implying more severe summer drought and more frequent fires after 5600 yr b p douglas fir western hemlock and western red cedar dominated the record marking the introduction of the present day cool moist climate however during the past 2800 yr increased douglas fir and decreased cedar suggest the possibility of reduced effective moisture at little lake

evidence for large amplitude biome and climate changes in atlantic canada during the last interglacial and mid wisconsinan periods abstract last interglacial and mid wisconsinan pollen data from sedimentary sequences of cape breton island in atlantic canada were analyzed to reconstruct biome and climate conditions our results show warm and humid climate with mean annual temperature 6 7 c higher than today up to 15 20 more sunshine and significantly longer growing season that fostered growth of temperate trees during the optimum of the last interglacial the northern limit of the deciduous forest biome was then about 500 km north of its modern limit towards the end of the interglacial the deciduous forest was replaced by conifer hardwood forest and boreal forest climate was then similar to modern the transition from interglacial to glacial was marked by a change towards coniferous forest related to colder and dryer conditions during the mid wisconsinan the development of forest tundra to boreal forest reflects migration of the arctic front and significant cooling with mean annual temperature anomalies of 8 to 12 c the overall time series reflect large amplitude climate changes that point to high sensitivity of the southeastern canadian margins likely as a response to latitudinal shifts of the gulf stream and variable strength of the labrador current together with changes in large scale atmospheric circulation pattern

galileo doppler measurements of the deep zonal winds at jupiter changes in the speed of the galileo probe caused by zonal winds created a small but measurable doppler effect in the probe relay carrier frequency analysis of the probe relay link frequency allows direct measurements of the speed of jupiter s zonal winds beneath the cloud tops the deep winds were prograde and strong reaching a sustained 190 to 200 meters per second at an altitude marked by a pressure of 24 bars the depth and strength of the zonal winds severely constrain dynamic modeling of the deeper layers and begin to rule out many shallow weather theories

estimate of jupiter s deep zonal wind profile from shoemaker levy 9 data and arnol d s second stability criterion abstract a number of one and two layer atmospheric models have been applied to the study of jupiter s tropospheric circulations over the past two decades in an effort to characterize the basic state properties of the zonal winds and to study the influence these winds have on the dynamics of long lived vortices like the great red spot by singling out the basic state that corresponds to neutral stability with respect to arnol d s second stability criterion as motivated by the results of a vortex tube stretching analysis of the voyager wind data and by fixing the stratification parameter using the c 454 20 msec 1 gravity wave speed determined from the shoemaker levy 9 impacts we arrive at a unique model with no free parameters the speed and direction of the zonal wind as a function of latitude for the model s lower layer is thus determined which roughly indicates the circulation in jupiter s interior below the water clouds predictions are that the westward jets change little with depth but that the eastward jets become stronger by 50 100

millennial scale climate instability during the early pleistocene epoch climate proxy records of the past 100 000 years show that the earth s climate has varied significantly and continuously on timescales as short as a few thousand years 1 7 similar variability has also recently been observed for the interval 340 500 thousand years ago8 these dramatic climate shifts expressed most strongly in the north atlantic region may be linked to and possibly amplified by alterations in the mode of ocean thermohaline circulation4 5 6 7 8 9 here we use sediment records of past iceberg discharge and deep water chemistry to show that such millennial scale oscillations in climate occurred over one million years ago this was a time of significantly different climate boundary conditions not only was the early pleistocene epoch generally warmer but global climate variations were governed largely by changes in earth s orbital obliguity our results suggest that such millennial scale climate instability may be a pervasive and long term characteristic of earth s climate rather than just a feature of the strong glacial interglacial cycles of the past 800 000 years

geomagnetic field control of 14c production over the last 80 ky implications for the radiocarbon time scale we have used a recent estimate of the geomagnetic dipole field strength over the last 80 ky to examine the extent to which changes in geomagnetic field intensity have affected the radiocarbon time scale the magnetic record was converted into a 14c production signal which was then used to produce a synthetic atmospheric 14c record using a two box model for the carbon cycle this calibration suggests that the geomagnetic field has been the main factor governing the production of cosmogenic 14c atoms over the period of time considered and that 14c changes due to other causes such as climatic changes have been of lesser importance the results indicate that the radiocarbon ages are 2 to 3 ky younger than true age in the interval 18 40 ky b p in good agreement with recent u th and 14c age comparisons moreover the results predict that a negligible difference between true and 14c ages should be observed around 45 50 ky

a reassessment of u th and14c ages for late glacial high frequency hydrological events at searles lake california u th isochron ages of tufas formed on shorelines suggest that the last pluvial event in lake lahontan and searles lake was synchronous at about 16 500 cal yr b p equivalent to a radiocarbon age of between 14 000 and 13 500 yr b p whereas the timing of this pluvial event determined by radiocarbon dating is on the order of 1000 yr younger the timing of seven distinct periods of near desiccation in searles lake during late glacial time has been reinvestigated for u th age determination by mass spectrometry u th dating of evaporite layers in the interbedded mud and salt unit called the lower salt in searles lake was hampered by the uncertainty in assessing the initial230th 232th of the samples the resulting ages corrected by a conservative range of initial230th 232th ratios suggest close correlation of the abrupt changes recorded in greenland ice cores dansgaard oeschger events and wet dry conditions in searles lake between 35 000 and 24 000 cal yr b p

geology and paleoecology of a mid wisconsin peat from the queen charlotte islands british columbia canada abstract a peat bed on east central graham island of the queen charlotte islands occurs within a nonglacial fluvial succession that is both overlain and underlain by glacial deposits radiocarbon dates of 27 500 400 and 45 700 970 yr b p at the top and base of the peat respectively indicate that it was deposited during the mid wisconsin nonglacial interval the peat is the first documented mid wisconsin organic deposit in northern coastal areas of british columbia three local pollen zones are represented the lowest zone pm 1 is restricted to sandy silt directly underlying the dated peat very high cyperaceae and moderate poaceae pollen percentages characterize zone pm 1 and a variety of other herbs are common suggesting an open landscape rather than a forested one the middle zone pm 2 is characterized by abundant pollen of picea tsuga mertensiana and cyperaceae and also contains pollen of abies a genus now absent from the queen charlotte islands graham island probably had extensive forests at this time but abundant pollen and macrofossils of cyperaceae and emergent aquatics such as hippuris vulgaris veronica scutellata potentilla palustris and menyanthes trifoliata indicate that there also were open wetland areas zone pm 3 also contains abundant arboreal pollen large amounts of sphagnum spores and selaginella selaginoides megaspores indicate succession of the wetland area at the sample site to a peat bog paleoecological analysis of the data suggests that subalpine vegetation elements were depressed by at least 400 m probably due to a cooler climate probable modern analogs in southeastern alaska and the presence of abies probably a amabilis indicate that precipitation was higher on eastern graham island during the mid wisconsin than at present

atmospheric waves and dynamics beneath jupiter s clouds from radio wavelength observations abstract we observed jupiter at wavelengths near 2 cm with the karl g jansky very large array vla in february 2015 these frequencies are mostly sensitive to variations in ammonia abundance and probe between 0 5 2 0 bars of pressure in jupiter s atmosphere within and below the visible cloud deck which has its base near 0 7 bars the resultant observed data were projected into a cylindrical map of the planet with spatial resolution of 1500 km at the equator we have examined the data for atmospheric waves and observed a prominent bright belt of radio hotspot features near 10 n likely connected to the same equatorial wave associated with the 5 m hotspots we conducted a passive tracer power spectral wave analysis for the entire map and latitude regions corresponding to eastward and westward jets and compare our results to previous studies the power spectra analysis revealed that the atmosphere sampled in our observation excluding the neb region is in a 2 d turbulent regime and its dynamics are predominately governed by the shallow water equations the great red spot grs is also very prominent and has a noticeable meridional asymmetry and we compare it and nearby storms with optical images we find that the meridional radio profile has a global north south hemisphere distinction and find correlations of it to optical intensity banding and to shear zones of the zonal wind profile over select regions of latitude amateur optical images taken before and after our observation complemented the radio wavelength map to investigate dynamics of the equatorial region in jupiter s atmosphere we find that two radio hotspots at 2 cm are well correlated with optical plumes in the neb additionally revealing they are not the same 5 m hotspot features correlated with optical dark patches between adjacent plumes this analysis exploits the vla s upgraded sensitivity and explores the opportunities now possible when studying gas giants especially atmospheric dynamics of layers beneath upper level clouds