textural characteristics and genesis of the aeolian sediments in the kuwaiti desert several types of aeolian deposits have been recognized in kuwait a smooth sand sheets that resemble desert floor sand b immobile sands that include rugged vegetated sand sheets and wadi fill deposits and c mobile sands that form active sand sheets and sand dunes simple size frequency curves illustrate the genetic relationship between the various aeolian sediment types the four size parameters namely mean size sorting skewness and kurtosis were calculated scatter plot diagrams of sorting versus mean size and sorting versus kurtosis are effective in differentiating smooth sand sheet deposits from dune sands active sand sheet deposits can also be recognized because they are usually located between the two end members smooth sand sheets and dune sands size parameters change with location regardless of their types coarsening and positive skewness usually increase downwind mineralogical and textural characteristics of the aeolian deposits in kuwait revealed that they are mostly derived from the lower mesopotamian muddy flood plain deposits the sand fraction of the al dibdibba gravelly deposits and the disintegrated material from calcretic and gypcretic duricrusts distribution of depositional and deflational areas indicates that the northern desert of kuwait is characterized by a positive sand budget whereas the southern desert has a negative sand budget

quantifying global warming from the retreat of glaciers records of glacier fluctuations compiled by the world glacier monitoring service can be used to derive an independent estimate of global warming during the last 100 years records of different glaciers are made comparable by a two step scaling procedure one allowing for differences in glacier geometry the other for differences in climate sensitivity the retreat of glaciers during the last 100 years appears to be coherent over the globe on the basis of modeling of the climate sensitivity of glaciers the observed glacier retreat can be explained by a linear warming trend of 0 66 kelvin per century

the influence of changing orbital parameters and surface boundary conditions on climate simulations for the past 18 000 years abstract general circulation model experiments at 3000 year intervals for the past 18 000 years were made to estimate the magnitude timing and pattern of the climatic response to prescribed changes of orbital parameters date of perihelion axial tilt eccentricity and glacial age lower boundary conditions ice sheets land albedo sea ice and sea surface temperature the experiments used the community climate model ccm of the national center for atmospheric research ncar the response of monsoon circulations and tropical precipitation to the orbitally produced solar radiation changes was much larger than the response to changes of glacial age boundary conditions the continental interior of eurasia was 2 4 k warmer in summer and summer monsoon precipitation of north africa south asia was increased by 10 20 between 12 000 and 6000 yr bp before present when perihelion occurred during northern summer rather than in winter as now and the earth s axial tilt was larger than now southern hemisphe

tidal cycles in the sediments of santa barbara basin the sediments of santa barbara basin a valuable source of information about the history of the california current show cyclic deposition in three properties here investigated varve thickness total organic carbon toc accumulation and fish scale abundance we analyzed the record since a d 1350 for varves a d 1120 for toc and a d 1200 for fish scales prominent periods are 169 yr 93 yr 51 4 yr 17 7 yr varve thickness 124 yr 56 yr 37 4 yr toc flux and 103 yr 128 yr fish scale abundance a surprising number of the varve and toc cycles can be interpreted as deriving from the common tidal cycles i e the 4 425 yr perigee period describing the changing distance between earth and moon and the 18 6 yr lunar nodal period which pertains to the lineup of earth moon and sun we suggest that the record of the basin is partly a result of pulsed sedimentation aligned with tides these findings support the hypothesis that a considerable portion of sediment destined for deposition in the center of the basin goes through a phase of shallow storage on the shelf where it can be remobilized through storms and tides mechanisms calling on tidally pulsed productivity or tidally influenced climate change are not excluded but are considered less attractive than remobilization fish scale cycles may reflect the influence of solar forcing

distribution of chlorite and kaolinite in eastern atlantic sediments off north africa chlorite in the atlantic sediments is predominantly derived from the atlas mountains kaolinite originates in the southern sahara and sahel zone these minerals may be used to reconstruct the tracks of two superimposed wind systems trade winds and harmattan wind a modified method for determining relative abundances of chlorite and kaolinite is presented

late pleistocene variability of arabian sea summer monsoon winds and continental aridity eolian records from the lithogenic component of deep sea sediments the modern indian ocean summer monsoon is driven by differential heating between the asian continent and the indian ocean to the south this differential heating produces a strong pressure gradient which drives southwest monsoon winds during june july and august satellite and meteorological observations aerosol measurements sediment trap studies and mineralogical studies indicate an atmospheric mode of transport for modern lithogenic sediments in the northwest arabian sea analyses of lithogenic grain size and mass accumulation rate mar records from the owen ridge indicate that eolian transport has been the primary mode of transport for the past 370 kyr visual inspection shows that the mar record is positively correlated with global ice volume as indicated by the marine 18o record in contrast the grain size record varies at a much higher frequency showing little correlation to either the mar or the 18o records spectral analyses confirm these relationships indicating that the lithogenic grain size and mar records are coherent only over the precession band whereby the grain size leads the mar by 124 8 kyr we conclude that an eolian transport mechanism is the only mechanism that allows for this phase difference and at the same time is supported by comparison of the grain size and mar with independent eolian records we use lithogenic grain size as a paleoclimatic indicator of summer monsoon wind strength and lithogenic mar as a paleoclimatic indicator of source area aridity these interpretations are supported by comparison of the lithogenic records to independent indicators of wind strength globigerina bulloides upwelling record and aridity a loess record from central china such comparisons indicate high coherence and zero phase relationships our work supports the findings of previous studies which have documented the link between monsoon strength and the earth s axial precession cycles both the lithogenic mar and the grain size records have high coherency with precessional insolation maximum lithogenic mar source area aridity is in phase with 18o global ice volume and leads maximum precessional insolation by 88 6 kyr we attribute this lead to the influence of glacial conditions on the aridity and therefore the deflation potential of the source areas maximum lithogenic grain size summer monsoon wind strength lags maximum precession by 148 9 kyr we attribute this lag both to the influence of global and or local ice volume and to the availability of latent heat from the southern hemisphere indian ocean the two of which combine to determine the strength of the indian ocean monsoon

clay minerals and sr nd isotopes of the sediments along the western margin of india and their implication for sediment provenance mineralogy and sr nd isotopic composition of the 2 m fraction of the holocene and late pleistocene sediments from 12 gravity cores collected along the western margin of india were used to delineate the provenance and understand the response of isotopes with respect to the source rock composition holocene sediments show distinct clay mineral associations representing three major sources illite chlorite rich sediments from the indus smectite dominated sediments from the deccan traps and kaolinite and smectite enriched sediments from gneissic rocks the mixing of indus derived sediment with the deccan traps derived sediment or the deccan traps derived sediment with gneissic rock derived sediment occurs in the deeper water cores sr isotopes are very sensitive to weathering and laterization weathering does not influence nd isotopes the 87sr 86sr ratios of the holocene sediments in shallow water cores are higher and fluctuated widely than those in deeper water cores nd correlates well with the clay mineral associations indicating source rock composition or mixing of source sediments kaolinite enriched sediments coupled with high sr ratios and low nd on the sw margin of india suggest intense chemical weathering in the hinterland the influence of the sediment from the ganges brahmaputra transported by the bay of bengal waters during the ne monsoon surface current or sw monsoon underwater current on the composition of the sediments of the sw indian margin is insignificant the late pleistocene sediments reflect a decrease of hydrolytic processes resulting in decrease of smectite and sr isotopic ratio clay minerals and nd values suggest that the provenance and transport pathways of the late pleistocene sediments are the same as those of the holocene for each region

cycles and shifts 1 300 years of multi decadal temperature variability in the gulf of alaska the gulf of alaska goa is highly sensi tive to shifts in north pacific climate variability here we present an extended tree ring record of january september goa coastal surface air temperatures using tree ring width data from coniferous trees growing in the mountain ranges along the goa the reconstruction 1514 1999 based on living trees ex plains 44 of the temperature variance although as the number of chronologies decreases back in time this value decreases to and remains around 30 before 1840 verification of the calibrated models is however robust utilizing sub fossil wood we extend the goa reconstruction back to the early eighth century the goa reconstruction correlates significantly 95 cl with both the pacific decadal oscillation index 0 53 and north pacific index 0 42 and therefore likely yields important information on past climate variability in the north pacific region intervention analysis on the goa reconstruction identifies the known twentieth century climate shifts around the 1940s and 1970s al though the mid 1920s shift is only weakly expressed in the context of the full 1 300 years record the well studied 1976 shift is not unique multi taper method spectral analysis shows that the spectral properties of the living and sub fossil data are similar with both records showing significant 95 cl spectral peaks at 9 11 13 14 and 18 19 years singular spectrum analysis identifies in order of importance significant oscillatory modes at 18 7 50 4 38 0 91 8 24 4 15 3 and 14 1 years the amplitude of these modes varies through time it has been suggested minobe in geo phys res lett 26 855 858 1999 that the regime shifts during the twentieth century can be explained by the interaction between pentadecadal 50 4 years and bi decadal 18 7 years oscillatory modes removal of these two modes of variance from our goa time series does indeed remove the twentieth century shifts but many are still identified prior to the twentieth century our analysis suggests that climate variability of the goa is very complex and that much more work is required to understand the underlying oscillatory behavior that is observed in instrumental and proxy records from the north pacific region

influence of the pacific decadal oscillation el nino southern oscillation and solar forcing on climate and primary productivity changes in the northeast pacific evidence of 11 year schwabe solar sunspot cycles el nino southern oscillation enso and the pacific decadal oscillation pdo were detected in an annual record of diatomaceous laminated sediments from anoxic effingham inlet vancouver island british columbia radiometric dating and counting of annual varves dates the sediments from ad 1947e1993 intact sediment slabs were x rayed for sediment structure lamina thickness and composition based on gray scale and subsamples were examined for diatom abundances and for grain size wavelet analysis reveals the presence of w2e3 w4 5 w 7a ndw9e12 year cycles in the diatom record and an w11e13 year record in the sedimentary varve thickness record these cycle lengths suggest that both enso and the sunspot cycle had an influence on primary productivity and sedimentation patterns sediment grain size could not be correlated to the sunspot cycle although a peak in the grain size data centered around the mid1970s may be related to the 1976e1977 pacific climate shift which occurred when the pdo index shifted from negative cool conditions to positive warm conditions additional evidence of the pdo regime shift is found in wavelet and cross wavelet results for skeletonema costatum a weakly silicified variant of s costatum annual precipitation and april to june precipitation higher spring april may values of the north pacific high pressure index during sunspot minima suggest that during this time increased cloud cover and concomitant suppression of the aleutian low al pressure system led to strengthened coastal upwelling and enhanced diatom production earlier in the year these results suggest that the 11 year solar cycle amplified by cloud cover and upwelling changes as well as enso exert significant influence on marine primary productivity in the northeast pacific the expression of these cyclic phenomena in the sedimentary record were in turn modulated by the phase of pdo as indicated by the change in period of enso and suppression of the solar signal in the record after the 1976e1977 regime shift

clay mineral accumulation rates in the arabian sea during the late quaternary abstract the regional variations in clay mineral concentrations in 39 turbidite free and undisturbed deep sea sediment cores from the arabian sea are compared with distribution patterns of clay mineral accumulation rates during the holocene and the last glaciation dust plumes from the red sea area arabia mesopotamia iran and pakistan can be traced by accumulation rates of mineral specific dust loads during the late quaternary the major proportions of aeolo marine sediments in the western arabian sea were derived from arabia during the summer season the clay mineral assemblage in these dust plumes consists of illite smectite kaolinite chlorite and palygorskite in decreasing order of abundance the distribution pattern of palygorskite in particular reveals that dust transport from southern arabia occurs mainly with northwesterly to westerly winds in the mid troposphere dust plumes from iran and pakistan which are characterized by high chlorite content are dispersed by northwesterly winds over the northwestern arabian sea dust contributions from the red sea area which are rich in smectite and characterized by the occurrence of amphiboles are transported to the gulf of aden the amount of dust related to northeast monsoon winds during the winter season appears to be negligible when compared to the proportions borne on other dust bearing winds in addition to aeolian contributions we distinguish two fluvial contributions a chlorite illite kaolinite and quartz rich assemblage from oman and pakistan into the gulf of oman and a smectite rich assemblage which is dominant off southern india originating from rivers that drain the indian subcontinent the significant difference between the holocene and glacial accumulation rates of wind transported clay minerals consist in the higher abundance of quartz illite and chlorite in the northwestern arabian sea during the last glaciation this pattern indicates intensified dust contributions by northwesterly winds from the persian gulf area which was dry during glacial times

on glacier retreat and drought cycles in the rocky mountains of montana and canada abstract the enigma of why mountain glacier started to retreat in the 1850s in the rocky mountains and elsewhere remains unresolved the most important factor affecting climate change presumably was a change in the mode of operation of the sun one or two decades earlier from irregular periodicity and low output to regular periods and greater brightness but the direct cause appears to have been the onset of drought in the 1830s interestingly there is no obvious solar information in the drought narrative in montana and southwestern canada the presence of tidal lines in the spectrum of the pacific decadal oscillation together with the presence of lines that could be interpreted as beat periods between solar and tidal forcing in the drought series suggests that the energy of solar variation is preempted for interference with tidal forcing within the system of oscillations informing precipitation patterns in the region the suggestion is supported by the presence of a strikingly dominant 12 5 year period in the drought series which is interpreted as a difference tone between the main sunspot cycle at 10 8 and a tidal period at 5 8 also this period is close to 2 3 of the nodal tide at 18 61

extracting a climate signal from 169 glacier records i constructed a temperature history for different parts of the world from 169 glacier length records using a first order theory of glacier dynamics i related changes in glacier length to changes in temperature the derived temperature histories are fully independent of proxy and instrumental data used in earlier reconstructions moderate global warming started in the middle of the 19th century the reconstructed warming in the first half of the 20th century is 0 5 kelvin this warming was notably coherent over the globe the warming signals from glaciers at low and high elevations appear to be very similar

the concentration of particulate aluminum and clay minerals in aerosols from the northern arabian sea abstract aerosol samples have been collected from the northern arabian sea during the northeast monsoon total atmospheric al concentrations ranged between 323 and 20 300 ng m 3 of air these are among the highest found over marine regions and demonstrate that the atmosphere is an important pathway for the transport of crustal material to the northern arabian sea and the gulf of oman the clay mineralogy of the soil sized particulates in the aerosol is similar to that of the surface sediments underlying the collection region but is different from that of the other sediments in the arabian sea the clay mineral data provide evidence supporting previously proposed theories that the relatively high concentrations of chlorite in the sediments of the northern arabian sea and the gulf of man are a consequence of the atmospheric transport of crustal material from the adjacent land masses

evidence for 18 6 year mn signal in temperature and drought conditions in north america since ad 1800 evidence for the 18 6 year lunar nodal mn term in air temperature is found at 30 stations in eastern north america since ad 1800 the mean discrepancy in epoch between maxima in temperature and maxima in the drought area index dai for the western united states vis a vis the maxima in the mn tide is 0 9 and 0 1 yr respectively also a cluster of 9 stations in western canada yields the 18 6 yr term which is out of phase with stations in eastern north america and is indicative of a standing tidal wave in the atmosphere this suggests that enhanced drought conditions in the western united states are neither recurrent nor rhythmic on a time scale of 20 yr but rather periodic with a period of 18 6 yr finally the rocky mountain system is seen as an influence for atmospheric tidal phenomena at epochs of maximum in the mn tide as well as for maxima in the temperature records and the dai

io heat flow from dark paterae abstract dark paterae on the jovian satellite io are evidence of recent volcanic activity some paterae appear to be entirely filled with dark volcanic material while others have only partially darkened floors dark paterae have area and heat flow longitudinal distributions that are bimodal as well as anti correlated with the longitudinal distribution of mountains on io at a global scale as part of our study of io s total heat flow we have examined the darkest paterae and quantified their thermal emission in order to assess their contribution this is the first time that the areas of the dark material in these paterae have been measured with such precision and correlated with their thermal emission dark paterae yield a significantly larger contribution to io s heat flow than dark volcanic fields dark paterae including loki patera yield at least 4 10 13 w or 40 of io s total heat flow in comparison dark flow fields yield 10 13 w or 10 of io s total heat flow of the total heat loss from dark paterae loki patera alone yields 10 13 w or 10 of io s total thermal emission

solar modulation of the north atlantic oscillation assisted by the tides abstract several prominent lines in the spectrum of the north atlantic oscillation nao are here considered as resulting from solar tidal modulation lines near 8 9 7 7 and 5 8 years are proposed to be a result of energy capture from internal oscillations into periods resulting from interference of solar and tidal cycles near 11 years solar and at 18 61 and 4 425 years tidal the dominant period in the range 10 5 years near 7 74 years is explained as a result of lock in of mutually supportive interference cycles that is the difference tones between solar cycles near 10 3 years and the two tidal periods at the solar period of 10 33 the two difference tones 7 74 and 23 22 are separated by precisely a factor of 3

inter decadal signals during the last millennium ad 1117 1992 in the varve record of santa barbara basin california annual varve thickness ad 1117 1992 from santa barbara basin has been decomposed into orthogonal components using singular spectrum analysis ssa to identify and retrieve inter decadal oscillations after removing all variability with periods greater than 150 years leading ssa eigenfunctions eofs identify four oscillatory pairs with periods of 100 58 25 and 12 years respectively based on 2500 simulated series and on two sided confidence intervals eofs 1 7 are significant at the 99 level and eofs 8 9 are significant at the 90 level oscillatory signals retrieved from the marine varves show an abrupt change in frequency and amplitude near ad 1600 the largest contribution to this environmental shift is given by the interdecadal components especially the 25 and the 12 year oscillation the near ad 1600 change may be related to multi annual events reported in the stratigraphy of the nearby santa monica basin and in dendrochronological records of the american southwest

development and testing of a 3d seismic velocity model of the po plain sedimentary basin italy abstract we built a 3d seismic model of the po plain and neighboring regions of northern italy covering altogether an area about 600 km by 300 km with an approximately 1 km spaced grid we started by collecting an extensive and diverse set of geological and geophysical data including seismic reflection and refraction profiles borehole logs and available geological information major geological boundaries and discontinuities have thus been identified and mapped into the model we used kriging to interpolate the geographically sparse information into continuous surfaces delimiting geological bodies with laterally varying thickness seismic wave properties have been assigned to each unit using a rule based system and v p v s and derived from other studies sedimentary strata although with varying levels of compaction and hence material properties may locally reach a thickness of 15 km and give rise to significant effects in seismic wave propagation we have used our new model to compute the seismic response for two recent earthquakes to test its performance results show that the 3d model reproduces the large amplitude and the long duration of shaking seen in the observed waveforms recorded on sediments whereas paths outside the basin may be well fit by more homogeneous 1d hard rock structure we conclude that the new model is suited for simulation of wave propagation mostly for t 3 s and may serve well as a constraint for earthquake location and further improvements via body or surface wave inversion

decadal scale climate drivers for glacial dynamics in glacier national park montana usa 1 little ice age 14th 19th centuries a d glacial maxima and 20th century retreat have been well documented in glacier national park montana usa however the influence of regional and pacific basin driven climate variability on these events is poorly understood we use tree ring reconstructions of north pacific surface temperature anomalies and summer drought as proxies for winter glacial accumulation and summer ablation respectively over the past three centuries these records show that the 1850 s glacial maximum was likely produced by 70 yrs of cool wet summers coupled with high snowpack post 1850 glacial retreat coincides with an extended period 50 yr of summer drought and low snowpack culminating in the exceptional events of 1917 to 1941 when retreat rates for some glaciers exceeded 100 m yr this research highlights potential local and ocean based drivers of glacial dynamics and difficulties in separating the effects of global climate change from regional expressions of decadal scale climate variability

phenomenological solar signature in 400 years of reconstructed northern hemisphere temperature record 1 we study the solar impact on 400 years of a global surface temperature record since 1600 this period includes the pre industrial era roughly 1600 1800 or 1600 1900 when negligible amount of anthropogenic added climate forcing was present and the sun realistically was the only climate force affecting climate on a secular scale and the industrial era roughly since 1800 1900 when anthropogenic added climate forcing has been present in some degree we use a recent secular northern hemisphere temperature reconstruction moberg et al 2005 three alternative total solar irradiance tsi proxy reconstructions lean et al 1995 lean 2000 wang et al 2005 and a scale by scale transfer climate sensitivity model to solar changes scafetta and west 2005 2006 the phenomenological approach we propose is an alternative to the more traditional computer based climate model approach and yields results proven to be almost independent on the secular tsi proxy reconstruction used we find good correspondence between global temperature and solar induced temperature curves during the pre industrial period such as the cooling periods occurring during the maunder minimum 1645 1715 and the dalton minimum 1795 1825 the sun might have contributed approximately 50 of the observed global warming since 1900 scafetta and west 2006 we briefly discuss the global cooling that occurred from the medieval maximum 1000 1100 ad to the 17th century minimum