responses of ocean circulation and carbon cycle to changes in the position of the southern hemisphere westerlies at last glacial maximum 1 we explore the impact of a latitudinal shift in the westerly wind belt over the southern ocean on the atlantic meridional overturning circulation amoc and on the carbon cycle for last glacial maximum background conditions using a state of the art ocean general circulation model we find that a southward northward shift in the westerly winds leads to an intensification weakening of no more than 10 of the amoc this response of the ocean physics to shifting winds agrees with other studies starting from preindustrial background climate but the responsible processes are different in our setup changes in amoc seemed to be more pulled by upwelling in the south than pushed by downwelling in the north opposite to what previous studies with different background climate are suggesting the net effects of the changes in ocean circulation lead to a rise in atmospheric pco2 of less than 10 atm for both northward and southward shift in the winds for northward shifted winds the zone of upwelling of carbon and nutrient rich waters in the southern ocean is expanded leading to more co2outgassing to the atmosphere but also to an enhanced biological pump in the subpolar region for southward shifted winds the upwelling region contracts around antarctica leading to less nutrient export northward and thus a weakening of the biological pump these model results do not support the idea that shifts in the westerly wind belt play a dominant role in coupling atmospheric co2 rise and antarctic temperature during deglaciation suggested by the ice core data

a model data comparison of δ13c in the glacial atlantic ocean 1 we compare a compilation of 220 sediment core 13c data from the glacial atlantic ocean with three dimensional ocean circulation simulations including a marine carbon cycle model the carbon cycle model employs circulation fields which were derived from previous climate simulations all sediment data have been thoroughly quality controlled focusing on epibenthic foraminiferal species such as cibicidoides wuellerstorfi or planulina ariminensis to improve the comparability of model and sediment core carbon isotopes the model captures the general 13c pattern indicated by present day water column data and late holocene sediment cores but underestimates intermediate and deep water values in the south atlantic the best agreement with glacial reconstructions is obtained for a model scenario with an altered freshwater balance in the southern ocean that mimics enhanced northward sea ice export and melting away from the zone of sea ice production this results in a shoaled and weakened north atlantic deep water flow and intensified antarctic bottom water export hence confirming previous reconstructions from paleoproxy records moreover the modeled abyssal ocean is very cold and very saline which is in line with other proxy data evidence

application of an inverse method to interpret 231pa 230th observations from marine sediments constraints then sediment 231 pa 230 th data for each time interval are combined with an advection scavenging model in order to determine their in consistency with the modern circulation estimate we find that the majority of sediment 231 pa 230 th data for the holocene lgm or h1 can be brought into consistency with the modern circulation if plausible assumptions are made about the large scale distribution of 231 pa and about model uncertainties moreover the adjustments in the data needed to reach compatibility with a hypothetical state of no flow no advection are positively biased for each time interval suggesting that the 231 pa 230 th data including that for h1 are more consistent with a persistence of some circulation than with no circulation our study does not imply that earlier claims of a circulation change during the lgm or h1 are inaccurate but that these claims cannot be given a rigorous basis given the current uncertainties involved in the analysis of the 231 pa 230 th data

the southern westerlies during the last glacial maximum in pmip2 simulations the southern hemisphere westerly winds are an important component of the climate system at hemispheric and global scales variations in their intensity and latitudinal position through an ice age cycle have been proposed as important drivers of global climate change due to their influence on deep ocean circulation and changes in atmospheric co2 the position intensity and associated climatology of the southern westerlies during the last glacial maximum lgm however is still poorly understood from empirical and modelling standpoints here we analyse the behaviour of the southern westerlies during the lgm using four coupled ocean atmosphere simulations carried out by the palaeoclimate modelling intercomparison project phase 2 pmip2 we analysed the atmospheric circulation by direct inspection of the winds and by using a cyclone tracking software to indicate storm tracks the models suggest that changes were most significant during winter and over the pacific ocean for this season and region three out four models indicate decreased wind intensities at the near surface as well as in the upper troposphere although the lgm atmosphere is colder and the equator to pole surface temperature gradient generally increases the tropospheric temperature gradients actually decrease explaining the weaker circulation we evaluated the atmospheric influence on the southern ocean by examining the effect of wind stress on the ekman pumping again three of the models indicate decreased upwelling in a latitudinal band over the southern ocean all models indicate a drier lgm than at present with a clear decrease in precipitation south of 40 s over the oceans we identify important differences in precipitation anomalies over the land masses at regional scale including a drier climate over new zealand and wetter over nw patagonia

southern ocean buoyancy forcing of ocean ventilation and glacial atmospheric co2 ocean circulation and dynamics can alter atmospheric co2 concentrations numerical modelling suggests that shifts in surface buoyancy loss and the location of upwelling can sequester co2 in the southern ocean during glacial periods

atlantic meridional overturning circulation during the last glacial maximum the circulation of the deep atlantic ocean during the height of the last ice age appears to have been quite different from today we review observations implying that atlantic meridional overturning circulation during the last glacial maximum was neither extremely sluggish nor an enhanced version of present day circulation the distribution of the decay products of uranium in sediments is consistent with a residence time for deep waters in the atlantic only slightly greater than today however evidence from multiple water mass tracers supports a different distribution of deep water properties including density which is dynamically linked to circulation

recent dyke induced large scale block movement at mount etna and potential slope failure here we report the results of a geodetic survey undertaken on mount etna between 1981 and 1988 observed horizontal ground movements in the vicinity of the valle del bove caldera demonstrate that dyke emplacement during 1983 and 1985 resulted in the 2 8 m eastward displacement of a block of western caldera rim a history of past instability and collapse along the rim is indicated by the presence of large back rotated blocks of prehistoric volcanics1 furthermore the unusually linear form of the present western rim indicates past slope failure along north south aligned surfaces and therefore that dyke induced collapse may have been an important agent in caldera enlargement we suggest a self sustaining mechanism whereby the stress regime generated as a consequence of the caldera s existence results in the repeated injection of north south orientated dykes adjacent to the western rim2 3 dilation associated with magma intrusion leads in turn to periodic phases of slope instability and failure of the cliff wall causing a progressive westward migration of the western rim

physical and biological regulation of the soft tissue carbon pump 1 we examine the relationship between aeolian iron deposition ocean circulation and atmospheric co2 in the context of a global ocean circulation and biogeochemistry model with a coupled atmospheric reservoir of co2 in common with previous models we find only a small reduction of atmospheric pco2 in response to an enhanced aeolian iron source consistent with last glacial maximum conditions we show this to be due to a combination of limiting factors including control of deep ocean iron concentrations by complexation to an organic ligand regional compensation in changes to export production and the maintenance of high preformed nutrient concentrations in deep water formation regions we also demonstrate a significant sensitivity of atmospheric pco2 to changes in the residual mean overturning circulation of the southern ocean dominated by its regulation of the accumulation of biogenic carbon in the deep ocean although it is not enough to explain the full drawdown of pco2 to glacial levels a reduction in overturning can lead to significant reduction in atmospheric pco2 providing mechanistic basis for the control by vertical mixing inferred from box models

spectral characterization of igneous rocks in the 8 to 12 μm region variation in the spectral response of silicates in the thermal infrared tir from 8 to 12 m is the foundation for potentially important applications in the lithologic characterization of terrestrial and extraterrestrial surfaces the purpose of this study is to elucidate the crystallo chemical basis for the variation in spectral behavior in terms which may be useful in remote sensing this has led to the definition of a new parameter scfm which is defined as the ratio sio2 sio2 cao feo mgo in minerals and rocks this parameter reflects the degree of depolymerization of the silica tetrahedra and is therefore highly correlated with the structure of tir reflectance spectra of major silicate minerals in both fine and coarse grained igneous rocks it is also a good numerical descriptor of igneous rock composition thus scfm is proposed as a very useful determinant for spectral identification of igneous rocks the scfm parameter was used to assess the effect of variations in location number and width of bands in discriminating rock composition an unfortunate ambiguity exists in the use of the term band which in spectroscopy indicates a feature in a spectrum and in remote sensing signifies a specific wavelength increment or channel the latter definition is used in this paper spectra of coarse particulate mineral and solid rock samples were acquired in the laboratory a regression analysis of bands varying in width from 0 2 to 1 4 m versus scfm results in coefficients of determination correlation coefficients r2 ranging from 0 88 for two 1 2 m wide bands to 0 97 for seven 0 2 m wide bands deletion of bands in the ozone absorption region 9 4 10 2 m results in a decrease in r2 by only 0 01 stimulation of system noise by addition of 5 random counts to the bands decreases r2 by only 0 03 because spectra structure is modified by weathering alteration and texture of the samples the validity of these results is limited to fresh igneous rocks with this constraint it is concluded that accurate spectral identification of igneous rock composition is not greatly affected by bandwidth or system noise it is the overall spectral envelope rather than the fine structure in the tir which contains most of the information diagnostic of igneous rock composition this permits design of remote sensing systems with broad bands and corresponding higher signal to noise which can be traded off against the important requirement for higher spatial resolution

remote determination of sif4 in volcanic plumes a new tool for volcano monitoring sif4 is probably a common trace component of fumarole gases on volcanoes arising from interactions between magmatic hf and wall rocks it is not distinguished from hf in conventional analyses a strong absorption band at 1032 cm 1 makes sif4 well suited to remote open path ftir spectroscopic techniques we report the first measurements of sif4 in volcanic gases at etna and vulcano sicily sif4 concentrations were low at etna but higher at vulcano where the so2 sif4 ratio was consistently around 1 7 10 2 1 thermodynamic considerations show that the hf sif4 ratio increases sharply with increasing temperature thus remote measurements of sif4 may offer a qualitative way of constraining fumarole temperatures we use our ftir measurements of hcl sif4 in combination with conventional measurements of hcl hf to infer an hf sif4 ratio for vulcano of 10 1 consistent with gas temperatures in the range 200 450 c

ground deformation and gravity changes accompanying the march 1981 eruption of mount etna abstract we present reults from simultaneous precise levelling and gravity surveys on mount etna covering the period august 1980 august 1981 the flank eruption of march 1981 erupted 18 35 10 5 m 3 of lava following it upward movements of more than 17 cm were observed close to the new fissure and a broad apparently independent uplift of 5 cm was observed 4 km to the west a zone of about 2 cm depression to the east of the fissure is insufficient to account for the volume of magma erupted gravity results show positive changes of up to 63 microgal and display good positive correlation with elevation changes both sets of measurements appear to be due to new intrusion of magma rather than subsurface magma drainage ground deformation close to the new fissure is well modelled by intrusion of a dyke in the zone 100 500 m below the surface striking along the fissure and of dip between 75 90 the gravity changes are modelled as due to a deeper intrusion of magma along the same line but some 1500 m below the surface the changes were not present immediately after the eruption but occurred during the ensuing 5 months it is proposed that this introduction of matter occurred by crack propagation along the fissure in the aftermath of the eruption towards the west of the fissure and some 4 km west of the summit ground deformation is modelled by intrusion of a dyke in the zone 300 1500 m below the surface and dipping at 80 85 again gravity changes appear to be due to magma intrusion at greater depth close to sea level in this case gravity changes are interpreted as due to magma density changes as a result of pressure increase in a larger scale fissure zone this same pressure increase may be forcing the new intrusion close to the surface and makes this part of the volcano a region of especially high risk

climate and marine carbon cycle response to changes in the strength of the southern hemispheric westerlies 1 it has been previously suggested that changes in the strength and position of the southern hemisphere westerlies could be a key contributor to glacial interglacial atmospheric co2 variations to test this hypothesis we perform a series of sensitivity experiments using an earth system model of intermediate complexity a strengthening of the climatological mean surface winds over the southern ocean induces stronger upwelling and increases the formation of antarctic bottom water enhanced ekman pumping brings more dissolved inorganic carbon dic rich waters to the surface however the stronger upwelling also supplies more nutrients to the surface thereby enhancing marine export production in the southern hemisphere and decreasing the dic content in the euphotic zone the net response is a small atmospheric co2 increase 5 ppmv compared to the full glacial interglacial co2 amplitude of 90 ppmv roughly the opposite results are obtained for a weakening of the southern hemisphere westerly winds

infrared image analysis of volcanic thermal features lascar volcano chile 1984 1992 fifteen landsat thematic mapper tm images of lascar volcano chile recorded between december 1984 and april 1992 document the evolution of a lava dome within the summit crater four of the scenes were acquired at night in every image the two short wavelength infrared bands 5 and 7 have detected thermal radiation from the volcano as a consequence of the planck distribution function the relative response of these two channels depends on the proportions of very hot 600 c surfaces occupying tiny pixel areas and broader regions at moderate temperatures 280 c intercomparison of bands 5 and 7 thereby provides a means for interpreting tm thermal anomalies even in the absence of ground observations pronounced changes in the configuration and intensity of the lascar anomaly suggest that the volcano has experienced at least two cycles of lava dome activity since 1984 the first of these progressed through a cooling period possibly reflecting a reduced flux of magmatic volatiles at the surface and culminated in an explosive eruption on september 16 1986 which appears to have completely destroyed the inferred lava dome the tm data indicate that a new dome had been emplaced by november 1987 more than 15 months before it was first discovered by local observers lascar s style of cyclical effusive and explosive activity is typical of many volcanoes and the remote sensing techniques presented herein could be applied elsewhere

the dependence of southern ocean meridional overturning on wind stress an eddy resolving numerical model of a zonal flow meant to resemble the antarctic circumpolar current is described andanalyzedusing the framework of j marshallandt radko in additionto windand buoyancy forcing at the surface the model contains a sponge layer at the northern boundary that permits a residual meridional overturning circulation moc to exist at depth the strength of the residual moc is diagnosed for different strengths of surface wind stress it is found that the eddy circulation largely compensates for the changes in ekman circulation the extent of the compensation and thus the sensitivity of the moc to the winds depend on the surface boundary condition a fixed heat flux surface boundary severely limits the ability of the moc to change an interactive heat flux leads to greater sensitivity to explain the moc sensitivity to the wind strength under the interactive heat flux transformed eulerian mean theory is applied in which the eddy diffusivity plays a central role in determining the eddy response a scaling theory for the eddy diffusivity based on the mechanical energy balance is developed and tested the average magnitude of the diffusivity is found to be proportional to the square root of the wind stress the moc sensitivity to the winds based on this scaling is compared with the true sensitivity diagnosed from the experiments

eddy saturation of equilibrated circumpolar currents abstractthis study uses a sector configuration of an ocean general circulation model to examine the sensitivity of circumpolar transport and meridional overturning to changes in southern ocean wind stress and global diapycnal mixing at eddy permitting and finer resolution the sensitivity of circumpolar transport to forcing magnitude is drastically reduced at sufficiently high resolution there is little or no sensitivity of circumpolar transport to wind stress even in the limit of no wind in contrast the meridional overturning circulation continues to vary with southern ocean wind stress but with reduced sensitivity in the limit of high wind stress both the circumpolar transport and meridional overturning continue to vary with diapycnal diffusivity at all model resolutions the circumpolar transport becomes less sensitive to changes in diapycnal diffusivity at higher resolution although sensitivity always remains in contrast the overturning circulation is more sensitive to change in diapycnal

connecting antarctic sea ice to deep ocean circulation in modern and glacial climate simulations antarctic sea ice formation plays a key role in shaping the abyssal overturning circulation and stratification in all ocean basins by driving surface buoyancy loss through the associated brine rejection changes in antarctic sea ice have therefore been suggested as drivers of major glacial interglacial ocean circulation rearrangements here the relationship between antarctic sea ice buoyancy loss deep ocean stratification and overturning circulation is investigated in last glacial maximum and preindustrial simulations from the paleoclimate modelling intercomparison project pmip the simulations show substantial inter model differences in their representation of the glacial deep ocean state and circulation which is often at odds with the geological evidence we argue that these apparent inconsistencies can largely be attributed to differing and likely insufficient antarctic sea ice formation discrepancies can be further amplified by short integration times deep ocean equilibration and sea ice representation should therefore be carefully evaluated in the forthcoming pmip4 simulations

on the abyssal circulation in the glacial atlantic an inverse method is used to evaluate the information contained in sediment data for the atlantic basin during the last glacial maximum defined here as the time interval 18 21 kyr before present the data being considered are an updated compilation of the isotopic ratios 18 o 16 o 18 o and 13 c 12 c 13 c of fossil shells of benthic foraminifera bottom dwelling organisms first an estimate of the abyssal circulation in the modern atlantic is obtained which is consistent with i climatologies of temperature and salinity of the world ocean circulation experiment ii observational estimates of volume transport at specific locations and iii the statements of a finite difference geostrophic model second estimates of water properties 18 o of equilibrium calcite or 18 oc and 13 c of dissolved inorganic carbon or 13 cdic derived from sediment data are combined with this circulation estimate to test their consistency with the modern flow it is found that more than approximately 80 of water property estimates 18 oc or 13 cdic are compatible with the modern flow given their uncertainties the consistency of glacial 13 cdic estimates with the modern flow could be rejected after two assumptions are made i the uncertainty in these estimates is 0 1 this uncertainty includes errors in sediment core chronology and oceanic representativity of benthic 13 c which alone appears better than this value on average and ii 13 cdic in the glacial deep atlantic was dominated by a balance between water advection and organic c remineralization measurements of 13 c on benthic foraminifera are clearly useful but the current uncertainties in the distribution and budget of 13 cdic in the glacial atlantic must be reduced to increase the power of the test

quantitative interpretation of atmospheric carbon records over the last glacial termination 1 the glacial interglacial rise in atmospheric pco2 is one of the best known changes in paleoclimate research yet the cause for it is still unknown forcing the coupled ocean atmosphere biosphere box model of the global carbon cycle bicycle with proxy data over the last glacial termination we are able to quantitatively reproduce transient variations in pco2 and its isotopic signatures 13c 14c observed in natural climate archives the sensitivity of the box model of the isotopic carbon cycle bicycle to high or low latitudinal changes is comparable to other multibox models or more complex ocean carbon cycle models respectively the processes considered here ranked by their contribution to the glacial interglacial rise in pco2 in decreasing order are the rise in southern ocean vertical mixing rates 30 ppmv decreases in alkalinity and carbon inventories 30 ppmv the reduction of the biological pump 20 ppmv the rise in ocean temperatures 15 20 ppmv the resumption of ocean circulation 15 20 ppmv and coral reef growth 5 ppmv the regrowth of the terrestrial biosphere sea level rise and the increase in gas exchange through reduced sea ice cover operate in the opposite direction decreasing pco2 during termination i by 30 ppmv according to our model the sequence of events during termination i might have been the following a reduction of aeolian iron fertilization in the southern ocean together with a breakdown in southern ocean stratification the latter caused by rapid sea ice retreat trigger the onset of the pco2 increase after these events the reduced north atlantic deep water nadw formation during the heinrich 1 event and the subsequent resumption of ocean circulation at the beginning of the bolling allerod warm interval are the main processes determining the atmospheric carbon records in the subsequent time period of termination i we further deduce that a complete shutdown of the nadw formation during the younger dryas was very unlikely changes in ocean temperature and the terrestrial carbon storage are the dominant processes explaining atmospheric 13c after the bolling allerod warm interval

pulsed lava effusion at mount etna during 2001 effusion rate and degassing data collected at mt etna volcano italy in 2001 show variations occurring on time scales of hours to months we use both long and short term data sets spanning january to august to identify this variation the long data sets comprise a satellite and ground based time series of effusion rates and the latter include field based effusion rate and degassing data collected may 29 31 the satellite derived effusion rates for january through august reveal four volumetric pulses that are characterized by increasing mean effusion rate values and lead up to the 2001 flank eruption peak effusion rates during these 23 57 day pulses were 1 2 m 3 s 1 in pulse 1 1 jan 4 mar 1 1 m 3 s 1 in pulse 2 5 mar 21 apr 4 2 m 3 s 1 in pulse 3 24 apr 18 jun 8 8 m 3 s 1 in pulse 4 23 jun 16 jul and 22 2 m 3 s 1 during the flank eruption 17 jul 9 aug rank order analysis of the satellite data shows that effusion rate values during the 2001 flank eruption define a statistically different trend than etna s persistent activity from jan 1 to jul 17 data prior to the flank eruption obey a power law relationship that may define an effusion rate threshold of f3 5 m 3 s 1 for etna s typical persistent activity our short term data coincide with the satellite derived peak effusion period of pulse 3 degassing at vent puff frequency shows a general increase from may 29 to 31 with hour long variations in both puff frequency and lava flow velocity effusion rate we identify five 3 14 h degassing periods that contain 26 shorter 19 126 min long oscillations this variation shows some positive correlation with effusion rate measurements during the same time period if a relationship between puff frequency and effusion rate is valid we propose that their short term variation is the result of changes in the supply rate of magma to the near vent conduit system therefore these short term data provide some evidence that the clear weeks to months long variation in etna s effusive activity january august 2001 was overprinted by a minutes to hour scale oscillation in shallow supply d 2004 elsevier b v all rights reserved

temperature of an active lava channel from spectral measurements kilauea volcano hawaii a narrow band spectroradiometer was used to determine the characteristic temperatures of a very active channeled lava flow for the phase 50 eruption of pu u o o on the east rift zone of kilauea volcano hawaii during the twilight of 19 february 1992 14 spectra of this activity were acquired over a 51 minute interval 18 29 to 19 20 hawaiian standard time hst from which the thermal distribution of energy of two 18 m2 areas one near the center and one near the margin of the flow may be investigated a twocomponent thermal mixing model applied to the data taken of the center of the channel gave in the most powerful instance 1 8x105 w m2 a crust temperature of 940 c a hot component temperature of 1120 c and a hot radiating area of 60 of the total area a simultaneous spectrum acquired near the channeled flow margin yielded a crust temperature of 586 c and a hot area of only 1 2 of the total area radiating at 1130 c average radiant flux densities recorded for the center of the lava channel 1 3x105 w m2 average are much greater than previous measurements of lava lakes 4 9x103 w m2 or recently emplaced lava flows maximum of 7 2x104 w m2 the energetic nature of this eruption is shown by satellite measurements made at 02 33 hst on 22 february 1992 by the advanced very high resolution radiometer in band 2 0 72 1 10 m these show the utility of using existing satellites with moderate resolution 1 km x 1 km pixels and high temporal coverage eight overpasses each day for hawaii as potential thermal alarms for rapidly assessing the hazard potential of large volcanic eruptions

southern ocean control of glacial amoc stability and dansgaard oeschger interstadial duration glacial periods exhibit abrupt dansgaard oeschger do climatic oscillations that are thought to be linked to instabilities in the atlantic meridional overturning circulation amoc great uncertainty remains regarding the dynamics of the do cycle as well as controls on the timing and duration of the individual events using ice core data we show that the duration of the warm interstadial phase is strongly correlated with antarctic climate and presumably with southern ocean so temperature and the position of the southern hemisphere sh westerlies we propose a so control on amoc stability and interstadial duration via the rate of antarctic bottom water formation meridional density pressure gradients agulhas leakage and so adiabatic upwelling this hypothesis is supported by climate model experiments that demonstrate so warming leads to a stronger amoc that is less susceptible to freshwater perturbations in the amoc stability diagram so warming and strengthening of the sh westerlies both shift the vigorous amoc branch towards higher freshwater values thus raising the threshold for amoc collapse the proposed mechanism could provide a consistent explanation for several diverse observations including maximum do activity during intermediate ice volume sh temperature and successively shorter do durations within each bond cycle it may further have implications for the fate of the amoc under future global warming

the volume and shape of the 1991 1993 lava flow field at mount etna sicily the 1991 1993 lava flow is the most voluminous flow erupted at mount etna sicily in over 300 years estimates of the volume obtained by various methods range from 205 106 m3 tanguy 1996 to over 500 106 m3 barberi et al 1993 this paper describes the results of an electronic distance measurement edm based field survey of the upper surface of the 1991 1993 flow field undertaken in 1995 the results were digitised interpolated and converted into a digital elevation model and then compared with a pre eruption digital elevation model constructed from a 1 25 000 contour map of the area based on 1989 aerial photographs our measurements are the most accurate to date and show that the 1991 1993 lava flow occupies a volume of 231 29 106 m3

gravity and tilt earth tides measured on an active volcano mt etna sicily abstract three kinemetrics tiltmeters and an askania tidal gravimeter were installed on mt etna sicily in order to test if previously reported anomalous tides are a permanent feature of the volcano s deformation two of the tiltmeters were installed near the summit of the volcano and the third on its flank the gravimeter recorded tides both on the volcano and 30 km away at catania comparison of the measured m2 tidal amplitudes and phases with values predicted theoretically shows that the gravity tides both on the volcano and at catania are within 4 of the theoretical values m2 tidal tilts are all less than 2 5 times those predicted theoretically these results imply that the anomalous tidal behaviour on mt etna reported previously is possibly a transient phenomenon associated with eruptions rather than a permanent modification of the solid earth tide by the volcanic structure

cooling rate of an active hawaiian lava flow from nighttime spectroradiometer measurements a narrow band spectroradiometer has been used to make nighttime measurements of the phase 50 eruption of pu u o o on the east rift zone of kilauea volcano hawaii on february 19 1992 a ger spectroradiometer was used to determine the cooling rate of an active lava flow this instrument collects 12 bit data between 0 35 to 3 0 m at a spectral resolution of 1 5 nm thirteen spectra of a single area on a pahoehoe flow field were collected over a 59 minute period 21 27 22 26 hst from which the cooling of the lava surface has been investigated a two component thermal mixing model flynn 1992 applied to data for the flow immediately on emplacement gave a best fit crustal temperature of 768 c a hot component at 1150 c and a hot radiating area of 3 6 of the total area over a 52 minute period within the time interval between flow resurfacings the lava flow crust cooled by 358 c to 410 c at a rate that was as high as 15 c min 1 our observations have significance both for satellite observations of active volcanoes and for numerical models of the cooling of lava flows during their emplacement

estimated strength of the atlantic overturning circulation during the last deglaciation the atlantic meridional overturning circulation affects the latitudinal distribution of heat and is a key component of the climate system proxy reconstructions based on sedimentary 231 pa 230 th ratios and the difference between surface and deep water radiocarbon ages indicate that during the last glacial period the overturning circulation was reduced during millennial scale periods of cooling 1 5 however much debate exists over the robustness of these proxies 6 8 here we combine proxy reconstructions of sea surface and air temperatures and a global climate model to quantitatively estimate changes in the strength of the atlantic meridional overturning circulation during the last glacial period we find that relative to the last glacial maximum the overturning circulation was reduced by approximately 14 sv during the cold heinrich event 1 during the younger dryas cold event the overturning circulation was reduced by approximately 12 sv relative to the preceding warm interval these changes are consistent with qualitative estimates of the overturning circulation from sedimentary 231 pa 230 th ratios in addition we find that the strength of the overturning circulation during the last glacial maximum and the holocene epoch are indistinguishable within the uncertainty of the reconstruction the atlantic meridional overturning circulation amoc is an important feature of the earth s climate system it is characterized by northward flowing water masses at the surface ocean deepwater formation in the north atlantic and southward flowing water masses in the intermediate to deep ocean this overturning cell is complemented by an underlying generally weaker reversed overturning cell that originates in the southern ocean in the following we use amoc to refer only to the upper overturning cell owing to the large heat capacity of water the northwardflowing near surface waters contribute effectively to the heat transport from the tropics to the mid and high latitudes and therefore affect the regional climate around the north atlantic 9 10 hence changes of the amoc strength can substantially influence climate in the north especially in europe the depth of the southward flowing waters and the strength of the circulation have changed in the past during the last glacial period abrupt warming events of several degrees within a few decades followed by slower cooling were detected in greenland ice cores 11 as effects of the so called dansgaardoeschger events were found far beyond the greenland ice sheet 1214 with patterns reminiscent of varying inter hemispheric heat distribution 15 16 they are believed to be the result of rapid changes of the amoc strength 17 other examples of a reduction or even a complete shutdown of the

evaluating southern ocean sea ice for the last glacial maximum and pre industrial climates pmip 2 models and data evidence sea ice is recognized as an important factor controlling climate conditions at high latitudes it has a major impact in controlling the ocean to atmosphere exchanges e g for co2 as well as surface oceanic conditions and deep water formation in the high latitude oceans being at the interface of two major components of the climate system sea ice is useful to evaluate and intercompare different climate models we here analyze the results of eight coupled climate models from which seven are from the pmip 2 database against available reconstructions for winter and summer sea ice extent around antarctica to evaluate the ability of models in representing different climate states we compare their results for both the pre industrial and the last glacial maximum lgm we find that models generally have identical seasonal ranges for the two climate states analyzed which is not supported by data inferences indeed data indicate that the lgm seasonality was enhanced compared to the pre industrial the shape of the sea ice distribution is also different in models circular around the antarctic continent and in reconstructions oval shaped distribution similar to modern sea ice distribution we show that models underestimating the sea ice extent for the pre industrial are also underestimating the last glacial maximum extent our results thus point to difficulties for climate models in representing the sea ice dynamics in the southern ocean

remote detection of hcl and so2 in volcanic gas from unzen volcano japan a telescope attached ft ir spectral radiometer was applied for remote measurement of chemical composition of the volcanic gas of unzen volcano japan which started erupting in november 1990 the observations were carried out at the site about 1 3 km away from the gas emitting region of the volcano in march and july 1992 absorption features of so2 vl and hcl were identified and column amounts of so2 and hcl of the volcanic gas plume were estimated using a nonlinear least squares method the so2 hcl ratio was in the range between 0 7 and 1 8 for both march and july observations this is the first remote ground based observation of hcl in volcanic gas

estimating and removing sensor induced correlation from advanced very high resolution radiometer satellite data in order to estimate the spatial covariance structure of sea surface temperature sst using advanced very high resolution radiometer avhrr satellite data autocorrelation induced by the sensor itself must be determined and then removed before the correlative properties of sst per se can be found sensor induced autocorrelation arises from 1 partially redundant sampling and 2 a nonideal impulse response simulation techniques are used to model the correlation structure produced by the avhrr results indicate that an autocorrelation of 0 39 at lag 1 arises from the overlap of adjacent pixels in the alongscan direction autocorrelations of 0 51 alongscan and 0 43 alongtrack arise from the sensor impulse response at lag 1 the autocorrelation at lag 2 is still significant 0 07 due to the sensor impulse response in the alongscan direction overall an autocorrelation of 0 46 occurs at lag 1 due to the combined effects of pixel overlap and the sensor impulse response at nadir procedures for removing this sensor induced correlation are presented oceanographically these results indicate for example that the gradients associated with sharp oceanic fronts will be suppressed application of the results to observed avhrr satellite data indicate that correlation length scales for sst over one portion of the gulf stream are on the order of 20 km the results also indicate that the effective spatial resolution of the avhrr is roughly 1 25 km at nadir somewhat lower than the commonly accepted value finally it is concluded that the accuracy of the calculations is limited by 1 an incomplete specification of the avhrr system modulation transfer function mtf and 2 the sine wave response function that is used to approximate the system mtf

multispectral thermal infrared mapping of the 1 october 1988 kupaianaha flow field kilauea volcano hawaii multispectral thermal infrared radiance measurements of the kupaianaha flow field were acquired with the nasa airborne thermal infrared multispectral scanner tims on the morning of 1 october 1988 the tims data were used to map both the temperature and emissivity of the surface of the flow field the temperature map depicted the underground storage and transport of lava the presence of molten lava in a tube or tumulus resulted in surface temperatures that were at least 10 c above ambient the temperature map also clearly defined the boundaries of hydrothermal plumes which resulted from the entry of lava into the ocean the emissivity map revealed the boundaries between individual flow units within the kupaianaha field in general the emissivity of the flows varied systematically with age but the relationship between age and emissivity was not unique distinct spectral anomalies indicative of silica rich surface materials were mapped near fumaroles and ocean entry sites this apparent enrichment in silica may have resulted from an acid induced leaching of cations from the surfaces of glassy flows such incipient alteration may have been the cause for virtually all of the emissivity variations observed on the flow field the spectral anomalies representing areas where the acid attack was most intense

the 1989 1990 eruption of redoubt volcano alaska impacts on aircraft operations abstract the december 1989 june 1990 eruption of redoubt volcano affected commercial and military air operations in the vicinity of anchorage alaska these effects were due to the direct impact of volcanic ash on jet aircraft as well as to the rerouting and cancellations of flight operations owing to eruptive activity between december and february five commercial jetliners were damaged from ash encounters the most serious incident took place on december 15 1989 when a boeing 747 400 aircraft temporarily lost power of all four engines after encountering an ash cloud as the airplane descended for a landing in anchorage while there were no injuries to passengers the damage to engines avionics and aircraft structure from this encounter is estimated at 80 million four additional encounters between jet aircraft and redoubt ash clouds occurred in the anchorage area on december 15 and 16 1989 and february 21 1990 none resulted in engine failure two additional encounters took place on december 17 1989 when jet airliners encountered the redoubt cloud over west texas at the time of these encounters the cloud was up to 55 hours old and had traveled in excess of 2 900 nautical miles 5 300 km following the december 15 encounters anchorage international airport remained open however most airline companies canceled operations for up to several days as communications between federal agencies and airlines improved and as a better understanding of the nature and behavior of ash rich eruption clouds was achieved most airlines resumed normal service by early january 1990 the resulting loss of revenue at anchorage international airport during several months following the eruption is estimated to total 2 6 million the impact on general aviation and military operations consisted mostly of cancellation and rerouting of flights

deflation of mount etna monitored by spaceborne radar interferometry ground based measurements of volcano deformation can be used to assess eruptive hazard but require the costly and often hazardous installation and maintenance of an instrument network here we show that spaceborne radar interferometry which has already shown its utility in mapping earthquake related deformation1 can be used to monitor long term volcano deformation two families of synthetic aperture radar images acquired from ascending and descending orbits by the satellite ers 1 and looking at mount etna from opposite sides cover the time period from 17 may 1992 to 24 october 1993 and include the second half of etna s most recent eruption despite artefacts of the interferometric technique we can observe a volcano wide deflation which is an expected consequence of the eruption but which had not previously been appreciated we quantify it using a simple model based on the change of pressure in a sphere located in an elastic half space the modelled deformation increases linearly with time until the end of the eruption our results show that it will be possible to use this technique to detect the inflation of volcanic edifices that usually precedes eruptions

carbon isotope constraints on the deglacial co2 rise from ice cores the stable carbon isotope ratio of atmospheric co2 13catm is a key parameter in deciphering past carbon cycle changes here we present 13catm data for the past 24 000 years derived from three independent records from two antarctic ice cores we conclude that a pronounced 0 3 per mil decrease in 13catm during the early deglaciation can be best explained by upwelling of old carbon enriched waters in the southern ocean later in the deglaciation regrowth of the terrestrial biosphere changes in sea surface temperature and ocean circulation governed the 13catm evolution during the last glacial maximum 13catm and atmospheric co2 concentration were essentially constant which suggests that the carbon cycle was in dynamic equilibrium and that the net transfer of carbon to the deep ocean had occurred before then

strength and geometry of the glacial atlantic meridional overturning circulation during the last glacial maximum the pattern of atlantic meridional overturning circulation was different from today a combination of sediment chemistry and a scavenging model suggests that the glacial circulation was shallower and at least as vigorous as today

turbulence characteristics of sediment laden flows in open channels the turbulence characteristics of sediment laden flows in open channels are investigated using two component laser doppler velocimetry suspensions of well sorted sands with diameters ranging from 0 15 mm to 0 24 mm flowing over nominally flat beds both fixed and erodible are studied in a tiltable recirculating flume various conceptual models that have been proposed to explain the mean field profiles are examined for consistency with respect to their implications for higher order characteristics no evidence is found to support either the traditional model associated with a decrease in the von karman constant or the more recently proposed models based on simple analogies to slightly stably stratified wall bounded flows a model based on small scale fluid particle interaction is suggested as more promising

thermal survey of mount etna volcano from space surveys of ground thermal anomalies and the monitoring of their evolution are of great importance in the study of volcanoes thermal monitoring techniques could be used in conjunction with classical monitoring tools i e seismological and deformation networks to give better predictions of the onset of a volcanic event in order to detect and emphasize small anomalies in the surface temperature of the ground we have developed a new method based on the joint use of two satellite radiometers the noaa advanced very high resolution radiometer avhrr for the quality of its thermal band calibration and the landsat thematic mapper tm for its high spatial resolution this method is applied to the mount etna volcano sicily and reveals several thermal anomalies one anomaly is already known and is associated with the permanently active craters of the summit zone the second is a larger area where an eruption occurred one week after the data acquisition 10 23 86 the general trend of the thermal anomalies leads to recognition of a large semi circular intrusive zone corresponding to the borders of the well known valle del bove

last glacial maximum and holocene climate in ccsm3 abstract the climate sensitivity of the community climate system model version 3 ccsm3 is studied for two past climate forcings the last glacial maximum lgm and the mid holocene the lgm approximately 21 000 yr ago is a glacial period with large changes in the greenhouse gases sea level and ice sheets the mid holocene approximately 6000 yr ago occurred during the current interglacial with primary changes in the seasonal solar irradiance the lgm ccsm3 simulation has a global cooling of 4 5 c compared to preindustrial pi conditions with amplification of this cooling at high latitudes and over the continental ice sheets present at lgm tropical sea surface temperature sst cools by 1 7 c and tropical land temperature cools by 2 6 c on average simulations with the ccsm3 slab ocean model suggest that about half of the global cooling is explained by the reduced lgm concentration of atmospheric co2 50 of present day concentrations there is an increase in the antarctic circumpolar current an

can paleoceanographic tracers constrain meridional circulation rates abstract the ability of paleoceanographic tracers to constrain rates of transport is examined using an inverse method to combine idealized observations with a geostrophic model considered are the spatial distribution accuracy and types of tracers required to constrain changes in meridional transport within an idealized single hemisphere basin measurements of density and radioactive tracers each act to constrain rates of transport conservative tracers while not of themselves able to inform regarding rates of transport improve constraints when coupled with density or radioactive observations it is found that the tracer data would require an accuracy one order of magnitude better than is presently available for paleo observations to conclusively rule out factor of 2 changes in meridional transport even when assumed available over the entire model domain when data are available only at the margins and bottom of the model radiocarbon is unable to constrain transport while density remains effective o

mechanisms of magma eruption and emplacement at mt etna between 1989 and 1992 the present eruption sequence of mt etna began during september 1989 with extensive fracturing and culminated in 1991 93 with the largest lava eruption this century1 here we present measurements of gravity and ground deformation which in conjunction with seismic data provide a detailed record of the processes occurring before and during eruption these reflect a complex interplay between magma injection into the paths of lowest compressive stress through the volcano flanks forcing elastic deformation and fracture growth in response to gravitational stresses we find that after the end of the eruptive activity in 1989 fractures in the south southeast flank of the volcano remained unfilled until some months before the 1991 93 eruption these results indicate the utility of microgravity monitoring as the precursory processes that we identify were largely undetected by seismic and ground deformation monitoring

relative dating of hawaiian lava flows using multispectral thermal infrared images a new tool for geologic mapping of young volcanic terranes the weathering of hawaiian basalts in arid and semiarid environments is accompanied by change in their thermal infrared emittance spectra the spectral differences can be measured and mapped with multispectral imaging systems the differences appear to be related to the degree of development preservation and alteration of glassy crusts the oxidation of iron and the accretion of silica rich surface veneers because the measurements are quantitative and in image format they are useful for estimating relative ages in geologic mapping of lava flows in hawaii this technique is most diagnostic for distinguishing among sparsely vegetated flows less than 1 5 ka in age

sediment suspension with rippled bed experiments on the suspension of sediment were performed in flume with and without sediment layer on the bottom for movable bed runs three dimensional sand ripples were found to affect seriously the features of suspended sediment the horseshoe vortices and the resulting bursts in the lee of the ripples entrain intermittently a large amount of sediment into the outer layer of flow details of the suspension process were studied using a sand ripple model made of plaster the result revealed that the vertical component of turbulent eddies is responsible for the suspension of sediment and the statistical distribution of the component was found to be the gaussian law the statistical distribution of the concentration fluctuation was observed to be highly skewed and the reason was determined to be the fact that the concentration increases with the power of eight against the vertical fluid velocity the period of the intermittent ejection of sediment agreed reasonably with those reported for natural geophysical flows thus the suspension of sediment in flows with rippled beds was proved to be significantly correlated with bursting phenomenon behind sand ripples

southern hemisphere westerly wind changes during the last glacial maximum model data comparison the southern hemisphere sh westerly winds are thought to be critical to global ocean circulation productivity and carbon storage for example an equatorward shift in the winds though its affect on the southern ocean circulation has been suggested as the leading cause for the reduction in atmospheric co2 during the last glacial period despite the importance of the winds it is currently not clear from observations or model results how they behave during the last glacial here an atmospheric modelling study is performed to help determine likely changes in the sh westerly winds during the last glacial maximum lgm using lgm boundary conditions the maximum in sh westerlies is strengthened by 1 m s 1 and moved southward by 2 at the 850 hpa pressure level boundary layer stabilisation effects over equatorward extended lgm sea ice can lead to a small apparent equatorward shift in the wind band at the surface further sensitivity analysis with individual boundary condition changes indicate that changes in sea surface temperatures are the strongest factor behind the wind change the hadam3 atmospheric simulations along with published pmip2 coupled climate model simulations are then assessed against the newly synthesised database of moisture observations for the lgm although the moisture data is the most commonly cited evidence in support of a large equatorward shift in the sh winds during the lgm none of the models that produce realistic lgm precipitation changes show such a large equatorward shift in fact the model which best simulates the moisture proxy data is the hadam3 lgm simulation which shows a small poleward wind shift while we cannot prove here that a large equatorward shift would not be able to reproduce the moisture data as well we show that the moisture proxies do not provide an observational evidence base for it

radiative temperature measurements at kupaianaha lava lake kilauea volcano hawaii field spectroradiometer data in the wavelength range of 0 4 2 5 m and spectral resolution of 1 5 nm have been used to compute the radiative temperature of the surface of kupaianaha lava lake kilauea volcano hawaii two sets of observations a total of 120 spectra were made on october 12 1987 and january 23 1988 when the lava lake was in a period of active overturning the area of the surface for which temperatures were measured was 0 23 0 55 m2 two numerical models of two and three components have been used to match the measured radiant flux ratios and to describe the surface of the lava pond in terms of radiant area and temperature three stages of activity on the lake surface are identified stage 1 characterized by magma fountaining and overturning events exhibited the hottest crustal temperatures 180 572 c and the largest fractional hot areas 10 3 stage 1 average flux densities were 2 2 104 w m2 the highest recorded for the three stages of activity on either day the largest radiative area of fresh magma was 29 at 1100 c while cooling from magmatic temperatures to newly formed crust at 790 c took place in a matter of seconds stage 2 marked by rifting events between plates of crust exhibited crustal temperatures between 100 and 340 c with fractional hot areas at least an order of magnitude lower than those found for stage 1 average flux densities calculated for three examples of stage 2 activity were 5 3 103 w m2 stage 3 which was quiescent periods when the lake was covered by a thick crust dominated the activity of the lake both temporally and spatially over 90 of the time the characteristic crustal temperature of stage 3 was 80 345 c with most solutions near 200 300 c and fractional hot areas of 10 5 of the viewing area average flux densities for stage 3 were 4 9 103 w m2 for many stage 3 examples a two component model was sufficient to describe the spectral data however for almost all of the stage 1 and 2 examples and the remainder of the stage 3 examples a three component model was required these determinations of lava temperature and radiant area have relevance for satellite and airborne measurements of the thermal characteristics of active volcanoes and indicate that temporal variability of the thermal output of lava lakes occurs on the time scale of seconds to minutes

magma movements in etna volcano associated with the major 1991 1993 lava eruption evidence from gravity and deformation the 1991 1993 eruption was probably the largest on mt etna for 300 years since then the volcano has entered an unusually quiescent period a comprehensive record of gravity and ground deformation changes presented here bracket this eruption and give valuable insight into magma movements before during and after the eruption the gravity and deformation changes observed before the eruption 1990 1991 record the intrusion of magma into the summit feeder and the sse trending fracture system which had recently been active in 1978 1979 1983 and 1989 creating the feeder dyke for the 1991 1993 eruption in the summit region gravity changes between 1992 and 1993 spanning the end of the eruption reflect the withdrawal of magma from the conduit followed more recently 1993 1994 by the re filling of magma in the conduit up to pre eruption levels in contrast in the vicinity of the fracture zone gravity has remained at the 1991 1992 level indicating that no withdrawal has occurred here rather magma has solidified in the fracture system and sealed it such that the 1993 1994 increase in magma level in the conduit was not accompanied by further intrusion into the flanks mass calculations suggest that a volume of at least 107 m3 of magma has solidified within the southeastern flank of the volcano

large inert carbon pool in the terrestrial biosphere during the last glacial maximum during each of the late pleistocene glacial interglacial transitions atmospheric carbon dioxide concentrations rose by almost 100 ppm the sources of this carbon are unclear and efforts to identify them are hampered by uncertainties in the magnitude of carbon reservoirs and fluxes under glacial conditions here we use oxygen isotope measurements from air trapped in ice cores and ocean carbon cycle modelling to estimate terrestrial and oceanic gross primary productivity during the last glacial maximum we find that the rate of gross terrestrial primary production during the last glacial maximum was about 40 10 pg c yr 1 half that of the pre industrial holocene despite the low levels of photosynthesis we estimate that the late glacial terrestrial biosphere contained only 330 pg less carbon than pre industrial levels we infer that the area covered by carbon rich but unproductive biomes such as tundra and cold steppes was significantly larger during the last glacial maximum consistent with palaeoecological data our data also indicate the presence of an inert carbon pool of 2 300 pg c about 700 pg larger than the inert carbon locked in permafrost today we suggest that the disappearance of this carbon pool at the end of the last glacial maximum may have contributed to the deglacial rise in atmospheric carbon dioxide concentrations

location and orientation of eruptive fissures and feederdykes at mount etna influence of gravitational and regional tectonic stress regimes abstract lava extrusion from fissures on the flanks of the etna volcano is a common feature of recent activity as evidenced by the eruptions of 1971 1981 1983 and 1985 and was of similar importance during prehistoric times we propose here a model within which the location and orientations of the large majority of historic eruptive fissures on etna s flanks together with their feeder dykes are explained within the framework of a gravitational stress regime stress orientations within this regime are controlled largely by the gross morphology of the volcano but are significantly modified by local topographic anomalies we propose that the gravitational stress regime largely supercedes an earlier developed regional tectonic stress regime which still operates in the sub volcanic basement and may remain the dominant control of eruptive fissure and feeder dyke disposition at lower altitudes on the flanks the proposed model is supported by 1 detailed examination of fissure locations and orientations and the relationship between fissure azimuths and topography 2 precise horizontal distance measurement and vertical ground deformation studies of a recent eruption and 3 qualitative physical modelling experiments in which coloured water is injected into solidified gelatine solutions representing variously shaped volcanic constructs a cautious approach is advocated when extrapolating trends of spatially limited fissure segments for the purpose of locating potential sites of magma ascent and implications of the model for hazard analysis are outlined

how important are southern hemisphere wind changes for low glacial carbon dioxide a model study 1 the response of atmospheric co2 to modifications in the strength and position of southern hemisphere westerlies is examined with the bern3d ocean model the model responds more sensitively to changes in the wind amplitude than to variations in latitudinal position depending on the model setup a 50 reduction in wind strength leads to a co2 drawdown of 3 34 ppm while a 50 increase results in a rise of 10 24 ppm a poleward shift of 5 lowers co2 by 2 16 ppm whereas an equatorward shift of 5 induces a co2 increase of 2 14 ppm physical and biological mechanisms equally contribute to the modeled changes in atmospheric co2 our results are in conflict with the hypothesis that southern hemisphere wind changes are responsible for the low atmospheric co2 concentrations during glacial periods

emissivity of terrestrial materials in the 3 5 μm atmospheric window remotely sensed infrared radiance emitted by a surface is a function both of its kinetic temperature and its spectral emissivity consequently assumptions are usually made about the emissivity of earth surface materials to allow their temperatures to be determined or vice versa to increase the accuracy of these assumptions the directional hemispherical spectral reflectance of a wide range of natural earth surface materials has been measured and is summarized here these include igneous metamorphic and sedimentary rocks desert varnish soils vegetation water and ice kirchhoff s law can be used to predict directional spectral emissivity from these data

the control of lava flow during the 1991 1992 eruption of mt etna abstract all the actions carried out in 1992 to protect the village of zafferana etnea from being invaded by lava are described an earthen barrier 234 m long and 21 m high was firstly built in january 1992 by accumulating with mechanical escavators 370 000 m 3 of earth scoriae and stones this embankment contained the lava for about one month and was overflowed by april 9 1992 three additional smaller earthen barriers lenght 90 160 m height 6 12 m were built in april to gain time while the lava front was descending towards zafferana from the overflowed first embankment the major effort of the 1992 operation consisted of several attempts at stopping the lava front advance by diverting the flow out from the natural and extensively tunnelled channel through a skylight near the vent the main intervention point was located in valle del bove at an elevation of 2000 m at 8 km from zafferana in a zone almost unaccessible from land helicopters were hence extensively used during the whole operation initial interventions called for attempts at plugging a tunnel by dumping into it linked concrete blocks hedgehogs and blasted portions of the solid levee each intervention caused the partial obstruction of the tunnelled channel which determined major increases of lava overflow in valle del bove and the consequent halt of the most advanced fronts however benefits were of brief duration at the most two weeks of respite before new lava fronts approached again and again the outskirts of zafferana the final successful intervention was carried out on may 27 29 an artificial channel was dug departing from the natural one the solid separation levee was thinned to 3 m and blasted by 7000 kg of explosives after the explosion 2 3 of the lava flowed spontaneously in the artificial channel and then the total diversion was obtained the tunnel being plugged by dumping into the natural flow 230 m 3 of lava boulders as a consequence of the intervention the active natural lava front that on may 27 was only 850 m from zafferana came to an halt as did the entire flow downhill from the diversion point bringing back the situation as it was five months earlier a few days after the beginning of the eruption with the new front of the diverted flow at 6 7 km from zafferana in june 1992 the effusion rate halved from 30 to 15 m 3 s and with this reduced thrust the lava was no longer capable of covering long distances five months after the conclusive intervention the diverted lava continues to flow over its initial natural field but remaining confined in the upper valle del bove without any new threat to zafferana

distinct modes of internal variability in the global meridional overturning circulation associated with the southern hemisphere westerly winds the internal variability of the global meridional overturning circulation gmoc in long term integration of the earth system model community earth system models cosmos is examined in this study two distinct modes of the gmoc which are closely linked to the southern hemisphere westerly winds sww anomalies are found to vary on multidecadaland centennial time scales the dominantmode is characterized by southern ocean dynamics strengthening and poleward shift of the sww associated with a positive phase of the southern annular mode yield ekman induced northward mass transport including a zonally asymmetric response in the southern ocean sea surface temperature and a cooling in the tropical pacific ocean due to large scale upwelling the second mode projects mainly onto the atlantic meridional overturning circulation amoc it is driven by a combination of sww variation and buoyancy forcing based on the relationship between the two modes together with the wind perturbation experiments the authors emphasize that the full amoc response to the sww change takes several centuries in their model the sea surface temperature in northern hemisphere high latitudes is significantly affected in this mode showing a largescale warming their results from a mid holocene experiment imply that both modes are independent from the climate background conditions in the holocene finally the authors argue that the natural modes of gmoc are important to understand trends in ocean circulation with consequences for heat and carbon budgets for past present and future climate

thermal radiance observations of an active lava flow during the june 1984 eruption of mount etna the thermal budget of an active lava flow observed on 20 june 1984 from the southeast crater of mount etna sicily italy was analyzed from data taken by the landsat thematic mapper the thematic mapper images constitute one of the few satellite data sets of sufficient spatial and spectral resolution to allow calibrated measurements on the distribution and intensity of thermal radiation from active lava flows using radiance data from two reflective infrared channels we can estimate the temperature and areas of the hottest parts of the active flow which correspond to hot 500 c fractures or zones at the flow surface using this technique we estimate that only 10 20 of the total radiated thermal power output is emitted by hot zones or fractures which constitute less than 1 of the observed surface area generally it seems that only where hot fractures or zones constitute greater than about 1 of the surface area of the flow will losses from such features significantly reduce internal flow temperatures using our radiance observations as boundary conditions for a multicomponent thermal model of flow interior temperature we infer that for the parts of this flow subject to analysis the boundary layer and flow thickness effects dominate over radiant zones in controlling the depression of core temperature

volcano monitoring using short wavelength infrared data from satellites data from remote sensing satellites operating in the short wavelength infrared can be used to measure temperatures of about 150 c and above the gain settings of the landsat thematic mapper tm sensors are such that to record pixel integrated temperatures from 150 c to over 1000 c requires the use of several spectral bands if the radiant source occupies less than a whole pixel as is the case for fumaroles or a crusted lava surface with incandescent cracks then the pixel integrated temperature is less than the actual surface temperature of the hot areas and appears to be different at each wavelength by determining pixel integrated temperature in two spectral bands we can estimate both the temperature and size of hot areas which occupy less than a complete pixel in some cases our observations provide the only available data on the state of activity of a particular volcano in others they support and refine field observations our landsat tm data reveal otherwise unobserved precursor and subsequent activity related to the september 1986 eruption of lascar volcano chile and supplement other data on the march 1986 eruption of augustine volcano alaska they also indicate the continued presence of lava lakes at erta ale ethiopia in the absence of any ground based observations and document minor eruptive activity at mount erebus antarctica landsat multispectral scanner data have been used to measure the variation in temperature along a lava flow on sierra negra galapagos islands which occurred in 1979

identification of cloud free pixels in inhomogenous surfaces from avhrr radiances a new method of distinguishing clear and cloud contaminated pixels from avhrr data is described whereas most previous methods have difficulty in identifying cloud contaminated pixels when the background is inhomogenous such as is the case for coastal regions or continental regions containing vegetated land and bare soil or land and water the present method is particularly suited to these situations examination of the measured reflectivities in channels 1 and 2 of the avhrr for these backgrounds and for clear skies suggests that the reflectivities are related linearly the linear relationship is understandable in terms of pixels being comprised of linear combinations of two different surface types advantage is taken of this relationship as well as the radiance in channel 4 to identify cloud free pixels for complex surface conditions the technique is readily automated and combined with other techniques that may be more suitable for homogenous backgrounds

emplacement and inflation of pahoehoe sheet flows observations and measurements of active lava flows on kilauea volcano hawaii inflated pahoehoe sheet flows have a distinctive horizontal upper surface which can be several hundred meters across and are bounded by steep monoclinal uplifts the inflated sheet flows we studied ranged from 1 to 5 m in thickness but initially propagated as thin sheets of fluid pahoehoe lava generally 20 30 cm thick individual lobes originated at outbreaks from the inflated front of a prior sheet flow lobe and initially moved rapidly away from their source velocities slowed greatly within hours due to radial spreading and to depletion of lava stored within the source flow as the outward flow velocity decreases cooling promotes rapid crustal growth at first the crust behaves plastically as pahoehoe toes form after the crust attains a thickness of 2 5 cm it behaves more rigidly and develops enough strength to retain incoming lava thus increasing the hydrostatic head at the flow front the increased hydrostatic pressure is distributed evenly through the liquid lava core of the flow resulting in uniform uplift of the entire sheet flow lobe initial uplift rates are rapid flows thicken to 1 m in 1 2 hours but rates decline sharply as crustal thickness increases and as outbreaks occur from the margins of the inflating lobe one flow reached a final thickness of nearly 4 m after 350 hr inflation data define power law curves whereas crustal cooling follows square root of time relationships the combination of data can be used to construct simple models of inflated sheet flows as the flow advances preferred pathways develop in the older portions of the liquid cored flow these pathways can evolve into lavatube systems within a few weeks formation of lava tubes results in highly efficient delivery of lava at velocities of several kilometers per hour to a flow front that may be moving 1 2 orders of magnitude slower if advance of the sheet flow is terminated the tube remains filled with lava that crystallizes in situ rather than draining to form the cave like lava tubes commonly associated with pahoehoe flows inflated sheet flows from kilauea and mauna loa are morphologically similar to some thick icelandic and submarine sheet flows suggesting a similar mechanism of emplacement the planar sheet like geometry of flood basalt flows may also result from inflation of sequentially emplaced flow lobes rather than nearly instantaneous emplacement as literal floods of lava

last glacial maximum ocean thermohaline circulation pmip2 model intercomparisons and data constraints the ocean thermohaline circulation is important for transports of heat and the carbon cycle we present results from pmip2 coupled atmosphere ocean simulations with four climate models that are also being used for future assessments these models give very different glacial thermohaline circulations even with comparable circulations for present an integrated approach using results from these simulations for last glacial maximum lgm with proxies of the state of the glacial surface and deep atlantic supports the interpretation from nutrient tracers that the boundary between north atlantic deep water and antarctic bottom water was much shallower during this period there is less constraint from this integrated reconstruction regarding the strength of the lgm north atlantic overturning circulation although together they suggest that it was neither appreciably stronger nor weaker than modern two model simulations identify a role for sea ice in both hemispheres in driving the ocean response to glacial forcing

competition between ocean carbon pumps in simulations with varying southern hemisphere westerly wind forcing we analyse the impact of migration and strength of southern hemisphere westerly winds on the ocean carbon cycle in a systematic sensitivity study with the university of victoria earth system climate model we find that changes in the biological pump are mainly driven by changes in ocean residence times while changes in export production are negligible changes in the biological and physical pumps are always of opposite sign with the physical pump being dominant for southward shifts and the biological pump being dominant for northward shifts furthermore changes in the pacific ocean carbon budget dictate the overall changes in global marine and atmospheric carbon overall atmospheric hbox co 2 increases and delta 14 hbox c decreases for northward shifts or a strengthening in wind forcing the opposite is true for a southward shift or a weakening in wind forcing combining forcings shift and intensity change results in a combination of their impacts with the direction of the shift being the first order forcing the terrestrial carbon reservoir absorbs releases 50 70 of the net oceanic carbon loss increase counterbalancing the effect on atmospheric hbox co 2

slope movement crisis on the east flank of mt etna volcano models for eruption triggering and forecasting abstract benchmarks installed on the upper eastern flank of mt etna in 1982 have subsided continually since then with the rate of subsidence twice accelerating prior to eruptions the first of these eruptions was in december 1985 and the second in september 1989 this pattern of accelerating downslope movement has also been observed prior to landslides and recent work applying knowledge of the failure of materials has shown that analysis of the inverse rate of these movements can be used to predict the time of failure post eruption analyses of geodetic or seismic data from volcanoes has shown that in several cases this approach could have been used to forecast eruptions weeks in advance applying the same principles to the accelerating subsidence on mt etna s eastern flank prior to the eruptions of 1985 and 1989 shows that rough estimates of eruption dates could have been obtained several months in advance these observations also suggest a speculative eruption triggering mechanism involving an interplay between slope creep deformation and extensional weakening over the zone of intrusion

what sets the mean transport through drake passage twelve experiments with two coarse resolutions of a global ocean model using a variety of surface forcings are analyzed to address the question of what sets the mean transport through drake passage seven of the experiments do not have an active sea ice model but the remaining five do previous theories have suggested that the drake passage transport is governed by the cape horn sverdrup transport or alternatively is proportional to the square root of the meridional ekman transport at the latitude of drake passage the results presented here do not support either of these theories the drake passage transport depends quite strongly on the isopycnal diffusivity parameter in the model and less strongly on the background vertical diffusivity and horizontal viscosity parameters however when the magnitudes of these parameters are fixed the results show a very strong correlation between drake passage transport and both the strength of the meridional ekman transport at the latitude of drake passage and the thermohaline circulation off the antarctic shelf the relationships are monotonic but not linear the best estimate is that the meridional ekman transport drives 100 sv of drake passage transport while the remaining 30 sv are driven by the global thermohaline circulation

effects of viewing geometry on avhrr observations of volcanic thermal anomalies abstract we investigate the influence of viewing geometry and dynamic range of the advanced very high resolution radiometer avhrr sensor on detecting eruptions on poorly monitored volcanoes numerical models of sunwarmed flows and typical active features associated with hawaiian eruptions overturning lava lakes surface flows of three different sizes and lava tubes with skylights show that new lava flows at 1000 c can be identified at all scan angles if the area of the activity exceeds 60 m 2 given a background temperature of 20 c more difficult is the detection of small breakouts of lava flows or tube fed flows when these features lie towards the edge of the swath because of the dynamic range and gain setting of the sensor bands 3 4 and 5 saturate at 49 c it is possible that similar thermal signatures may be produced when inactive flows are heated by the sun the ability of the avhrr to detect on going activity in hawaii in july 1991 is tested by comparing landsat thematic mapper and nadir avhrr scenes obtained within 3 5 hours of each other for an active pahoehoe flow field with a well developed tube system this comparison shows that within the area of thermally alarmed avhrr pixels

vertical ground deformation on mount etna 1975 1980 we present the results of repeated precise leveling between the years 1975 and 1980 of an 11 km traverse over the summit of mount etna together with data from a network of dry tilt stations measured between 1976 and 1980 both methods demonstrate that little vertical movement occurs except on fresh lava flows which show a consistent pattern of downward movement interpreted as compaction and downhill sliding of lava after it has solidified other small vertical movements of a few centimetres recorded on the leveling traverse appear to be related to activity particularly the eruptions from a new vent area on the southeast side of the summit in 1978 and 1979 models of the recorded movement indicate that a small amount of magma was already stored in a dike below this eruption site as much as two years before it was erupted although the bulk of the magma for these eruptions was not stored in the upper few kilometres of the volcano the latter conclusion is supported by the dry tilt data which are dominated by local movements of 10 to 20 microradians with no consistent pattern of movement over the whole volcano

lowering of glacial atmospheric co2 in response to changes in oceanic circulation and marine biogeochemistry 1 we use an earth system model of intermediate complexity climber 2 to investigate what recent improvements in the representation of the physics and biology of the glacial ocean imply for the atmospheric concentration the coupled atmosphere ocean model under the glacial boundary conditions is able to reproduce the deep salty stagnant water mass inferred from antarctic deep pore water data and the changing temperature of the entire deep ocean when carbonate compensation is included in the model we find a co2 drawdown of 43 ppmv associated mainly with the shoaling of the atlantic thermohaline circulation and an increased fraction of water masses of southern origin in the deep atlantic fertilizing the atlantic and indian sectors of the southern ocean north of the polar front leads to a further drawdown of 37 ppmv other changes to the glacial carbon cycle include a decrease in the amount of carbon stored in the terrestrial biosphere 540 pg c which increases atmospheric co2 by 15 ppmv and a change in ocean salinity resulting from a drop in sea level which elevates co2 by another 12 ppmv a decrease in shallow water caco3 deposition draws down co2 by 12 ppmv in total the model is able to explain more than two thirds 65 ppmv of the glacial to interglacial co2 change based only on mechanisms that are clearly documented in the proxy data a good match between simulated and reconstructed distribution of 13c changes in the deep atlantic suggests that the model captures the mechanisms of reorganization of biogeochemistry in the atlantic ocean reasonably well additional poorly constrained mechanisms to explain the rest of the observed drawdown include changes in the organic carbon caco3 ratio of sediment rain reaching the seafloor iron fertilization in the subantarctic pacific ocean and changes in terrestrial weathering

the effect of a northward shift in the southern hemisphere westerlies on the global ocean we examine the effect of a northward shift in the position of the southern hemisphere subpolar westerly winds swws on the vertical and horizontal distribution of temperature and salinity in the world ocean a northward shift of the swws causes a latitudinal contraction of the subpolar gyres in the southern hemisphere sh in the indian and pacific this leads to subsurface warming in the subtropical thermocline as the southern margins of the gyres move into latitudes characterised by warmer surface air temperature sat the layers at mid depth below 400 m depth become ventilated by warmer water we characterize the approximation of the ventilated thermocline in our coarse resolution model using a set of passive tracer experiments and illustrate how the northward shift in the swws causes an equatorward shift in the latitude of origin of water ventilating layers deeper than 400 m in the indian and pacific leaving the total surface ventilation of the upper 1200 m unchanged in contrast the latitudinal constraint on the antarctic circumpolar current posed by the drake passage causes a cooling and freshening throughout the atlantic thermocline here subsurface thermocline water originates from higher latitudes under the wind shift on longer timescales atlantic cooling and freshening is reinforced by a reduction in north atlantic deep water nadw formation and surface salinification of the indian and pacific oceans in effect the latitude of zero wind stress curl in the swws regulates the relative importance of the cold water route via the drake passage and the warm water route associated with thermocline water exchange via the indian ocean thus a more northward location of the swws corresponds with a reduced salinity contrast between the indian pacific oceans and the atlantic this results in reduced nadw formation also a more northward location of the swws facilitates the injection of cool fresh antarctic intermediate water into the south atlantic subtropical gyre beyond these changes on a millennial timescale the deep ocean warms throughout the water column in response to the wind shift global salinity stratification also becomes less stable as more saline water remains at the surface and accumulates in the indian and pacific thermocline the freshening of the deep ocean reflects a reduced stirring of the global ocean due to reduced net circulation arising from a misalignment between the westerlies and the topographically constrained acc our results lend support to the idea that a more equatorward location of the sww maximum during glacial climates contributed to cooler and fresher conditions in the atlantic inhibiting nadw

circumpolar response of southern ocean eddy activity to a change in the southern annular mode 1 analysis of satellite altimeter data reveals anomalously high eddy kinetic energy eke in the antarctic circumpolar current acc during the period 2000 2002 around 2 3 years earlier 1998 the circumpolar eastward wind stress as quantified by the southern annular mode sam showed a significant positive peak and we have shown previously that the acc peaked around 1998 in response an eddy resolving ocean model is used to investigate the delay between wind forcing and the eddy response and demonstrates that the lag is due to the time taken to influence the deep circulation of the acc winds over the southern ocean have shown a strong climatic increase over the past few decades if this increase in winds is also reflected as an increase in eddy activity as our analysis suggests it might then the increased poleward heat flux may have played a significant role in the observed warming of the southern ocean citation meredith m p and a m hogg 2006 circumpolar response of southern ocean eddy activity to a change in the southern annular mode geophys res lett 33 l16608 doi 10 1029 2006gl026499

synchronous volcanic eruptions and abrupt climate change 17 7 ka plausibly linked by stratospheric ozone depletion glacial state greenhouse gas concentrations and southern hemisphere climate conditions persisted until 17 7 ka when a nearly synchronous acceleration in deglaciation was recorded in paleoclimate proxies in large parts of the southern hemisphere with many changes ascribed to a sudden poleward shift in the southern hemisphere westerlies and subsequent climate impacts we used high resolution chemical measurements in the west antarctic ice sheet divide byrd and other ice cores to document a unique 192 y series of halogen rich volcanic eruptions exactly at the start of accelerated deglaciation with tephra identifying the nearby mount takahe volcano as the source extensive fallout from these massive eruptions has been found 2 800 km from mount takahe sulfur isotope anomalies and marked decreases in ice core bromine consistent with increased surface uv radiation indicate that the eruptions led to stratospheric ozone depletion rather than a highly improbable coincidence circulation and climate changes extending from the antarctic peninsula to the subtropics similar to those associated with modern stratospheric ozone depletion over antarctica plausibly link the mount takahe eruptions to the onset of accelerated southern hemisphere deglaciation 17 7 ka

the role of southern ocean processes in orbital and millennial co2 variations a synthesis abstract recent progress in the reconstruction of atmospheric co 2 records from antarctic ice cores has allowed for the documentation of natural co 2 variations on orbital time scales over the last up to 800 000 years and for the resolution of millennial co 2 variations during the last glacial cycle in unprecedented detail this has shown that atmospheric co 2 varied within natural bounds of approximately 170 300 ppmv but never reached recent co 2 concentrations caused by anthropogenic co 2 emissions in addition the natural atmospheric co 2 concentrations show an extraordinary correlation with southern ocean climate changes pointing to a significant direct or indirect influence of climatic and environmental changes in the southern ocean region on atmospheric co 2 concentrations here we compile recent ice core and marine sediment records of atmospheric co 2 temperature and environmental changes in the southern ocean region as well as carbon cycle model experiments in order to quantify the effect of potential southern ocean processes on atmospheric co 2 related to these orbital and millennial changes this shows that physical and biological changes in the so are able to explain substantial parts of the glacial interglacial co 2 change but that none of the single processes is able to explain this change by itself in particular changes in the southern ocean related to changes in the surface buoyancy flux which in return is controlled by the waxing and waning of sea ice may favorably explain the high correlation of co 2 and antarctic temperature on orbital and millennial time scales in contrast the changes of the position and strength of the westerly wind field were most likely too small to explain the observed changes in atmospheric co 2 or may even have increased atmospheric co 2 in the glacial also iron fertilization of the marine biota in the southern ocean contributes to a glacial drawdown of co 2 but turns out to be limited by other factors than the total dust input such as bioavailability of iron or macronutrient supply

southern hemisphere westerly wind changes during the last glacial maximum paleo data synthesis changes in the strength and position of southern hemisphere westerly winds during the last glacial cycle have been invoked to explain both millennial and glacial interglacial climate fluctuations however neither paleo models nor paleodata agree on the magnitude or even the sign of the change in wind strength and latitude during the most studied glacial period the last glacial maximum lgm compared to the recent past this paper synthesizes paleo environmental data that have been used to infer changes in lgm winds data compilations are provided for changes in terrestrial moisture dust deposition sea surface temperatures and ocean fronts and ocean productivity and existing data on southern hemisphere ocean circulation changes during the lgm are summarized we find that any hypothesis of lgm wind and climate change needs to provide a plausible explanation for increased moisture on the west coast of continents cooler temperatures and higher productivity in the subantarctic zone and reductions in agulhas leakage around southern africa our comparison suggests that an overall strengthening an equatorward displacement or no change at all in winds could all be interpreted as consistent with observations if a single cause related to the southern westerlies is sought for all the evidence presented then an equatorward displacement or strengthening of the winds would be consistent with the largest proportion of the observations however other processes such as weakening or poleward shifts in winds a weakened hydrological cycle extended sea ice cover and changed buoyancy fluxes cannot be ruled out as potential explanations of observed changes in moisture surface temperature and productivity we contend that resolving the position and strength of westerly winds during the lgm remains elusive based on data reconstructions alone however we believe that these data reconstructions of environmental conditions can be used in conjunction with model simulations to identify which processes best represent westerly wind conditions during the lgm

a chronology of the 1991 to 1993 mount etna eruption using advanced very high resolution radiometer data implications for real time thermal volcano monitoring between december 1991 and march 1993 a continuous effusive eruption at mount etna built a 7 6 km2 lava flow field flows extended to within 1 km of the town of zafferana before a successful artificial diversion was carried out higher up the volcano during this eruption the spaceborne advanced very high resolution radiometer avhrr acquired 308 images on which the activity could be detected since these data can be freely and directly available such coverage potentially allows regular real time monitoring ground observations and a flow map that we produced using a spot image and electronic distance measurement allowed us to develop and test data extraction techniques avhrr radiance maps were consistent with known locations of surface activity these documented the transition from channel to tube fed phases the changing threat to zafferana and flow diversion quantitative analysis of the avhrr data enabled estimation of active lava area thermal flux effusion rates and total flow field volume our estimates for eruption rate and total flow field volume 5 6 to 7 6 m3 s and 220 106 to 300 106 m3 respectively are in agreement with published ground based estimates of 5 8 m3 s and 235 106 m3 these correlations demonstrate the high degree of confidence that can now be placed in interpretations of avhrr time series for eruptions where ground based data are scanty

simulated impact of altered southern hemisphere winds on the atlantic meridional overturning circulation 1 previous work has suggested that the strength and latitudinal position of the southern hemisphere sh mid latitude westerly winds has an important impact on climate and the atlantic meridional overturning circulation amoc we probe this hypothesis by conducting ensembles of experiments using the gfdl cm2 1 coupled ocean atmosphere model with altered sh wind stress we find consistent with previous work that enhanced reduced and poleward equatorward displaced sh westerly winds lead to an amoc intensification weakening while the amoc takes more than a century to respond fully to the altered sh winds initial effects in the north atlantic can occur within a few decades the amoc changes generate sst and surface air temperature responses in the north atlantic and adjacent continental regions in the southern hemisphere the atmosphere responds to the altered ocean circulation with a further strengthening and poleward movement of the sh winds thereby constituting a modest positive feedback

monitoring an effusive eruption at piton de la fournaise using radar and thermal infrared remote sensing data insights into the october 2010 eruption and its lava flows

last glacial maximum co2 and δ13c successfully reconciled 1 during the last glacial maximum lgm 21 000 years ago the cold climate was strongly tied to low atmospheric co2 concentration 190 ppm although it is generally assumed that this low co2 was due to an expansion of the oceanic carbon reservoir simulating the glacial level has remained a challenge especially with the additional 13c constraint indeed the lgm carbon cycle was also characterized by a modern like 13c in the atmosphere and a higher surface to deep atlantic 13c gradient indicating probable changes in the thermohaline circulation here we show with a model of intermediate complexity that adding three oceanic mechanisms brine induced stratification stratification dependant diffusion and iron fertilization to the standard glacial simulation which includes sea level drop temperature change carbonate compensation and terrestrial carbon release decreases co2 down to the glacial value of 190 ppm and simultaneously matches glacial atmospheric and oceanic 13c inferred from proxy data lgm co2 and 13c can at last be successfully reconciled

southern ocean wind response to north atlantic cooling and the rise in atmospheric co2 modeling perspective and paleoceanographic implications 1 a recent study found enhanced upwelling rates in the southern ocean during the last glacial termination that coincided with the deglacial warming in antarctica and the rise in atmospheric co2 they hypothesized that the intensification of southern hemisphere midlatitude westerlies the presumed cause of the increased wind driven upwelling was triggered by an initial cooling within the glacial north atlantic whose influence was then communicated to the southern midlatitudes through an atmospheric teleconnection in this study we explore the viability of the above hypothesis using a modeling strategy focusing on the atmospheric teleconnection in simulations where north atlantic cooling was applied the model intertropical convergence zone shifted southward and westerlies and wind stress over southern ocean increased by as much as 25 while the perennial westerly anomalies occur over the entire southern ocean they are strongest over the south pacific during the austral winter when the wind stress anomalies were applied to an earth system model incorporating interactive marine biogeochemistry atmospheric co2 rises between 20 and 60 ppm depending on the biological response we thus confirm the viability of the proposed atmospheric teleconnection hypothesis the teleconnection appears to involves two distinct steps first the north atlantic cooling shifts the intertropical convergence zone southward weakening the southern branch of the hadley circulation and second how the altered hadley circulation in turn modifies the structure of midlatitude westerlies in the south pacific via the former s influence on the southern hemisphere subtropical jet this study underscores the control of the northern hemisphere has on southern midlatitude westerlies mediating by tropical circulation in contrast to past paleoclimate hypotheses that the magnitude and position of the southern midlatitude westerlies was controlled by global mean temperature our results do not preclude other potential mechanisms for affecting southern ocean ventilation in particular through oceanic pathways