a high resolution micromorphological record of changing landscapes and climates on the western loess plateau of china during oxygen isotope stage 5 abstract the micromorphological characteristics of a continuous set of block samples from 24 38 m depth in a well section on jiuzhoutai mountain lanzhou china are described the shape of the magnetic susceptibility curve together with previously published radiocarbon luminescence and geomagnetic dates indicates that this sample set encompasses the whole of the last interglacial s1 palaeosol complex and extends into the overlying and underlying loess l1 and l2 units seven pedosedimentary units are recognised on the basis of trends in the bulk properties and the key micromorphological indicators excrements textural concentrations shell fragments and calcite and gypsum features high rates of loess deposition with significant cryogenic activity gypsum precipitation and only weak bioturbation characterised oxygen isotope stage ois 6 and ois 4 at lanzhou depositional rates were moderately high in ois 5d and 5b with slightly higher bioturbation and no significant cryogenesis or gypsum precipitation ois 5e 5c and 5a were marked by low rates of accretion more extensive bioturbation and limited leaching this reconstruction reflects the pedosedimentary responses to fluctuating dominances of monsoonal controls during this period of global climatic change comparison of earlier micromorphological results from sites to west and east of lanzhou along a dry to humid climatic gradient indicate a clear regional pattern with reduced loess accumulation rates and enhanced bioturbation and leaching in the humid east tianshui and xian clay translocation occurred only in ois 5e at xian the warmest and most humid site on the transect

micromorphological variation of the s 1 paleosol across northwest china abstract a micrornorphological approach based upon sets of closely spaced thin sections taken from three sites located along a climatic and depositional gradient has been utilised to reconstruct the sequence of pedogenic and sedimentary events leading to the development of the s1 paleosol in northwest china two main pedosedimentary stages related to regional changes in monsoonal controls are evident at each site although the resolution processes and resultant features vary in a manner reflecting differences in climate and rates of loess deposition around xining in the west where loess accumulation rates were high and pedogenic processes were restricted to shallow leaching and limited bioturbation by the low rainfall s 1 comprises two discrete weakly developed paleosol units separated by a less pedogenically altered layer of loess in contrast at sites farther away from the loess source area in the more humid southeast s 1 is a thinner welded and more pedogenically developed unit dominated by the effects of extensive leaching bioturbation and sometimes even clay translocation processes

role of indian ocean warming in the development of philippine sea anticyclone during enso 1 the anomalous low level anticyclone near the philippines and suppressed convection over the western pacific associated with the mature warm phase of el nino southern oscillation enso have been suggested as important elements in the interaction between enso and the east asian monsoon we examined the causes of these anomalies in the circulation and convection using a newly developed linear baroclinic model that includes interactive moist processes of the cumulus convection and surface heat fluxes a conventional version of the linear model forced by prescribed heating indicates that the diabatic cooling due to suppressed convection over the maritime continent generates the philippine sea anticyclone from a series of the moist linear model experiments we found that the modest warming of the indian ocean in addition to the strong warming in the central eastern pacific and weak cooling in the western pacific is significant to suppress the convection over the maritime continent observed data also show a coincidence of the development between the philippine sea anticyclone indian ocean warming and the ascending motion over the indian ocean supporting the model results the above results indicate that the atmosphere ocean system in the indian ocean may be one of important factors to improve predictability of the east asian climate during enso

loess paleosol stratigraphy of dukso area namyangju city korea south abstract as korea lies between china with a drier climate and the wetter japanese islands the korean loess paleosol stratigraphy constitutes an important record of variations in the east asian monsoon climate the loess paleosol sequence consists of three loess layers l1ll1 l1ll2 and l2 and three paleosols l1ss1 s1 and s2 in the study area l1ll1 accumulated near the surface and is only about 5 cm in outcrop because it was removed for farming l1ss1 is about 103 cm thick soil crack structures developed in the upper part of l1ss1 were formed by shrinkage or as seasonally frozen ground soil wedges during the early cold dry stage of glacial period l2 is 48 cm thick with osl ages of 167 000 and 186 000 yr magnetic susceptibilities of paleosols were higher than the loess layers fine quartz grains in the loess layers are characterized by rounded shape and pitted surfaces based on the presence of the at tephra osl ages soil color soil crack structure magnetic susceptibility and median diameter the loess paleosol sequence of the dukso section can be correlated with the chinese loess paleosol sequence between mis 2 and 7

peatlands of the western siberian lowlands current knowledge on zonation carbon content and late quaternary history the western siberian lowlands wsl are the world s largest high latitude wetland and possess over 900 000 km 2 of peatlands the peatlands of the wsl are of major importance to high latitude hydrology carbon storage and environmental history analysis of the existing russian data suggests that the mean depth of peat accumulation in the wsl is 256 cm and the total amount of carbon stored there may exceed 53 836 million metric tons a synthesis of published and unpublished radiocarbon dates indicates that the peatlands first developed at the end of the last glacial with a rapid phase of initiation between 11 000 and 10 000 cal yr bp initiation slowed after 8000 cal yr bp and reached a nadir at 4000 cal yr bp there has been renewed initiation particularly south of 621n following 4000 cal yr bp the initial development of peatlands in the wsl corresponds with the warming at the close of the pleistocene cooling after 4000 cal yr bp has likely led to increased permafrost and increased peatland development particularly in central and southern regions cold and dry conditions in the far north may have inhibited peatland formation in the late holocene r 2002 elsevier science ltd all rights reserved

nonlinear intraseasonal phases of the east asian summer monsoon extraction and analysis using self organizing maps abstractthe hypothesis that regional characteristics of the east asian summer monsoon easm result from the presence of nonlinear coupled features that modulate the seasonal circulation and rainfall at the intraseasonal time scale is advanced in this study to examine this hypothesis the authors undertake the analysis of daily easm variability using a nonlinear multivariate data classifying algorithm known as self organizing mapping som on the basis of various som node analyses four major intraseasonal phases of the easm are identified the first node describes a circulation state corresponding to weak tropical and subtropical pressure systems strong upper level jets weakened monsoonal winds and cyclonic upper level vorticity this mode related to large rainfall anomalies in southeast china and southern japan is identified as the mei yu baiu phase the second node represents a distinct circulation state corresponding to a strengthened subtropical high monsoonal winds and anticyclonic upper lev

loess stratigraphy in central china abstract loess sequences in central china provide a detailed record of climate changes during the last 2 5 million years at least 44 major shifts from glacial to interglacial conditions occurred during this time in china prolonged loess deposition lasting more than 40 millennia occurred eleven times with only four of these intervals in brunhes chron the climate oscillations took place with increased frequency between 2 4 and 0 5 ma compared to the last half million years major shifts toward cooler and drier climates occurred at about 2 4 ma 1 2 ma and 0 5 ma while less pronounced shifts are dated to 1 65 ma 0 8 ma and 0 2 ma three of the last four reversals of the earth s magnetic field whose lithostratigraphic position has been detail are recorded in a glacial deposit the low field magnetic susceptibility of loess and soils which reflects the concentration of ultrafine magnetite is related to the degree of pedogenesis and serves as a proxy measure of climate the accumulation rate of the magnetite was fairly constant throughout the last 1 2 million years and can serve as a measure of time susceptibility records from localities near xifeng and luochuan located 160 km apart are compared and used to define informal lithostratigraphic units in the loess plateau of china

on the interannual variability of the bonin high associated with the east asian summer monsoon rain in order to assess how the bonin high affects interannual variability of the east asian summer monsoon easm around the korean peninsula the pulsation of the bonin high and its association with teleconnection patterns was examined the major factor for the interannual intensity of the easm is the center position of the bonin high rather than its center pressure up to 12 harmonics over time can be used to reconstruct the bonin high demonstrating its intraseasonal variation the interannual variability of the bonin high correlates with the tibet high this correlation is dominant for the easm onset time though not its retreat the primary teleconnection pattern reliant up on the interannual variability of the bonin high is the western pacific oscillation wpo in april in relation to long term variability the correlation between the wpo and the bonin high appears to contribute to the retreat stage of the easm which has itself increased since the mid 1970s furthermore the wpo in may and the tibet correlation has marked the onset rather than the retreat of the easm since the 1970s this highly correlated pattern since the mid 1970s may be the result of el nino

indian ocean capacitor effect on indo western pacific climate during the summer following el nino significant climate anomalies persist through the summer june august after el nino dissipates in spring over the equatorial pacific they include the tropical indian ocean tio sea surface temperature sst warming increased tropical tropospheric temperature an anomalous anticyclone over the subtropical northwest pacific and increased mei yu baiu rainfall over east asia the cause of these lingering el nino effects during summer is investigated using observations and an atmospheric general circulation model gcm the results herein indicate that the tio warming acts like a capacitor anchoring atmospheric anomalies over the indo western pacific oceans it causes tropospheric temperature to increase by a moist adiabatic adjustment in deep convection emanating a baroclinic kelvin wave into the pacific in the northwest pacific this equatorial kelvin wave induces northeasterly surface wind anomalies and the resultant divergence in the subtropics triggers suppressed convection and the anomalous anticyclone the gcm results support this kelvin wave induced ekman divergence mechanism in response to a prescribed sst increase over the tio the model simulates the kelvin wave with low pressure on the equator as well as suppressed convection and the anomalous anticyclone over the subtropical northwest pacific an additional experiment further indicates that the north indian ocean warming is most important for the kelvin wave and northwest pacific anticyclone a result corroborated by observations these results have important implications for the predictability of indo western pacific summer climate the spatial distribution and magnitude of the tio warming rather than simply whether there is an el nino in the preceding winter affect summer climate anomalies over the indo western pacific and east asia

origin and weathering properties of loess paleosol sequence in the goseong area on the east coast of south korea abstract this study aims to investigate the origin and weathering properties of the loess paleosol sequence in the goseong area on the east coast of south korea and to discuss the local sediment inputs and their paleoclimatic implications the geochemical properties suggest that the largest proportion of the sequence originated from the chinese loess plateau and or its source areas with a smaller quantity originating from the weathering products of the bedrock around the section although its origin can be regarded as the chinese loess plateau and or its source areas the sequence shows more weathered features than the chinese loess plateau moreover the weathering environments in south korea were different from those in the chinese loess plateau the difference in weathering properties may be attributed to the more humid climatic conditions in south korea the abundance of local sediment input to the sequence was controlled by sea level fluctuations in the east sea of korea and the global ice sheet developments during the glacial and interglacial cycles in the quaternary because local sediment occupies only minor proportions in the sequence the monsoon and westerly circulations in northeast asia played an important role in the loess formations in south korea as well as in the chinese loess plateau

world wide delivery of river sediment to the oceans new data and new estimates from old data show that rivers with large sediment loads annual discharges greater than about 15 times 10 6 tons contribute about 7 times 10 9 tons of suspended sediment to the ocean yearly extrapolating available data for all drainage basins the total suspended sediment delivered by all rivers to the oceans is about 13 5 times 10 9 tons annually bedload and flood discharges may account for an additional 1 2 times 10 9 tons about 70 of this total is derived from southern asia and the larger islands in the pacific and indian oceans where sediment yields are much greater than for other drainage basins

teleconnections in the geopotential height field during the northern hemisphere winter abstract contemporaneous correlations between geopotential heights on a given pressure surface at widely separated points on earth referred to as teleconnections in this paper are studied in an attempt to identify and document recurrent spatial patterns which might be indicative of standing oscillations in the planetary waves during the northern hemisphere winter with time scales on the order of a month or longer a review of existing literature on the subject reveals the existence of at least four such patterns the north atlantic and north pacific oscillations identified by walker and bliss 1932 a zonally symmetric seesaw between sea level pressures in polar and temperature latitudes first noted by lorenz 1951 and what we will refer to as the pacific north american pattern which has been known to operational long range forecasters in this country since the 1950 s a data set consisting of nmc monthly mean sea level pressure and 500 mb height analyses for a 15 year period is used as a basis fo

shift in the summer rainfall over the yangtze river valley in the late 1970s 1 the summer rainfall over the middle lower valley of the yangtze river and over the whole eastern china experienced a notable regime shift in about 1979 this change is consistent with a simultaneous jump like change in the 500 hpa geopotential height 500 over the northern pacific the rainfall over the yangtze river valley is closely related to the 500 averaged over the area 20 25 n 125 140 e with a correlation coefficient of 0 66 for the period 1958 1999 since 1980 the subtropical northwestern pacific high snph has enlarged intensified and extended southwestward the changes in the snph are strongly associated with the variations of the sea surface temperatures ssts of the eastern tropical pacific and tropical indian ocean the anomalies of these ssts responsible primarily for the shift of the summer rainfall over the yangtze river through the changes in snph precede the 500 signals with different leading times

interannual and interdecadal variations of the east asian summer monsoon and tropical pacific ssts part i roles of the subtropical ridge the interannual relationship between the east asian summer monsoon and the tropical pacific ssts is studied using rainfall data in the yangtze river valley and the ncep reanalysis for 1951 96 the datasets are also partitioned into two periods 1951 77 and 1978 96 to study the interdecadal variations of this relationship a wet summer monsoon is preceded by a warm equatorial eastern pacific in the previous winter and followed by a cold equatorial eastern pacific in the following fall this relationship involves primarily the rainfall during the pre mei yu mei yu season may june but not the post mei yu season july august in a wet monsoon year the western north pacific subtropical ridge is stronger as a result of positive feedback that involves the anomalous hadley and walker circulations an atmospheric rossby wave response to the western pacific complementary cooling and the evaporation wind feedback this ridge extends farther to the west from the previous winter to the following fall resulting in an 850 hpa anomalous anticyclone near the southeast coast of china this anticyclone 1 blocks the pre mei yu and mei yu fronts from moving southward thereby extending the time that the fronts produce stationary rainfall 2 enhances the pressure gradient to its northwest resulting in a more intense front and 3 induces anomalous warming of the south china sea surface through increased downwelling which leads to a higher moisture supply to the rain area a positive feedback from the strong monsoon rainfall also appears to occur leading to an intensified anomalous anticyclone near the monsoon region this sst subtropical ridge monsoon rainfall relationship is observed in both the interannual timescale within each interdecadal period and in the interdecadal scale the sst anomalies sstas change sign in northern spring and resemble a tropospheric biennial oscillation tbo pattern during the first interdecadal period 1951 77 in the second interdecadal period 1978 96 the sign change occurs in northern fall and the tbo pattern in the equatorial eastern pacific sst is replaced by longer timescales this interdecadal variation of the monsoon sst relationship results from the interdecadal change of the background state of the coupled ocean atmosphere system this difference gives rise to the different degrees of importance of the feedback from the anomalous circulations near the monsoon region to the equatorial eastern pacific in a wet monsoon year the anomalous easterly winds south of the monsoon enhanced anomalous anticyclone start to propagate slowly eastward toward the eastern pacific in may and june apparently as a result of an atmosphere ocean coupled wave motion these anomalous easterlies carry with them a cooling effect on the ocean surface in 1951 77 this effect is insignificant as the equatorial eastern pacific sstas already change from warm to cold in northern spring probably as a result of negative feedback processes discussed in enso mechanisms in 1978 96 the equatorial eastern pacific has a warmer mean sst a stronger positive feedback between ssta and the walker circulation during a warm phase tends to keep the ssta warm until northern fall when the eastward propagating anomalous easterly winds reach the eastern pacific and reverse the ssta

a holocene east asian winter monsoon record at the southern edge of the gobi desert and its comparison with a transient simulation the east asian winter monsoon eawm exhibits significant variability on intraseasonal interannual and interdecadal time scales and the variability can be extended to holocene centennial and millennial scales previous holocene eawm proxy data records which were mostly located in central eastern and southern china did not show a consistent holocene eawm history therefore it is difficult to provide insights into mechanisms of the long term winter monsoon variability on the basis of the records eolian sediments at the southern edge of the gobi desert western china are sensitive to the eawm changes and less affected by the east asian summer monsoon due to an obstruction of the qinghai tibet plateau this paper presents a comparison between a well dated holocene eawm record and coupled climate model simulations so as to explore physical processes and influencing factors of the holocene eawm sediment samples from two holocene eolian sedimentary sections huangyanghe a and huangyanghe b were acquired at the southern edge of the gobi desert chronologies were established based on twenty bulk organic matter ams 14c ages and five pollen concentrates ams 14c ages proxy data including grain size total organic carbon magnetic susceptibility and carbonate content were obtained from the two eolian sections the grain size standard deviation model was applied to determine components sensitive to variability of the holocene eawm after a comparison of environmentally sensitive grain size components and proxy data the 20 200 m component at the huangyanghe a and the 20 159 m component at the huangyanghe b section were selected as indicators of the holocene eawm which show a strong early holocene winter monsoon and a decline of the winter monsoon since the mid holocene we also present equilibrium and transient simulations of the climate evolution for the holocene using a state of art coupled climate model the community climate system model version 3 ccsm3 indices for the holocene eawm were calculated and are consistent with the reconstructed holocene eawm intensity the simulations indicate that orbital forcing effects on the land sea temperature and sea level pressure contrast can account for the observed eawm trends other forcings that were present in the early holocene including the remnant laurentide ice sheet and meltwater forcing in the north atlantic were not responsible for the holocene trends

burial of terrestrial organic matter in marine sediments a re assessment 1 calculations based on recent observations indicate that approximately one third of the organic matter presently being buried in marine sediments may be of terrestrial origin with the majority of this terrestrial organic matter tom burial occurring in muddy deltaic sediments these calculations further suggest that the remineralization of terrestrial organic matter in the oceans is also much less efficient than that of marine organic matter these two underappreciated observations have important implications in terms of our understanding of the controls on the global carbon cycle from a paleoceanographic perspective the results presented here also suggest that changes in tom burial on glacial interglacial timescales have the potential to impact the global carbon cycle i e atmospheric co2 levels

characterization of siberian arctic coastal sediments implications for terrestrial organic carbon export surface sediments were collected during the 2000 transarctic expedition along the siberian arctic coastline including the ob yenisey khatanga lena and indigirka estuaries sediments were chara

loess is not just the accumulation of dust most regrettably there is much misuse of terminology in connection with the concept of loess and the interpretation of its origin people often speak and write incorrectly about loess accumulation even loess specialists who are aware of the fact that loess as a concept has to satisfy at least 10 criteria loess is not simply dust carried and deposited by wind dust only becomes loess after the passage of a certain amount of time in a given geographical zone i e only through diagenesis in certain ecological environments to state that loess is of aeolian origin is an oversimplification and an incorrect definition because an aeolian origin applies only to the dust from which the loess has been formed we are aware of the fact that airborne dust cannot be transformed into loess in every geographical environment but only under those conditions typical of semi arid grassland or steppe or forested steppe the process primarily occurs where the rate of dust accumulation exceeds sheet wash or weathering soil formation rates if the rate of dust accumulation is less than that of surface erosion or of soil biogenetic processes the dust then develops into soil or through intensive weathering and increased precipitation into loam or clay only part of the aeolian dust transported and deposited in a zone suitable for loess formation remains there permanently and is transformed in situ into loess dust not affected by diagenesis is usually further transported by snowmelt or rainwash and is only transformed into loess after it has been redeposited the loess itself however is easily erodible and its minerals are readily reworked and reaccumulated and given the appropriate conditions it readily undergoes diagenesis again we do not always have sufficient evidence to determine whether a given loess body is of primary or secondary origin traditionally the minerals making up primary loess have been regarded as originating in dust accumulated by aeolian processes secondary loess by contrast is different from typical loess in many ways and it is not unusual to find various loess series in which superimposed dust fractions have been transformed into loess by different processes recently we have observed that the origin of various types of loess is governed by differences in litho ecological conditions rather than by the way in which the mineral material from which the loess is derived dust has been primarily accumulated loessification is therefore determined by environmental conditions

real time multivariate indices for the boreal summer intraseasonal oscillation over the asian summer monsoon region the boreal summer intraseasonal oscillation bsiso of the asian summer monsoon asm is one of the most prominent sources of short term climate variability in the global monsoon system compared with the related madden julian oscillation mjo it is more complex in nature with prominent northward propagation and variability extending much further from the equator in order to facilitate detection monitoring and prediction of the bsiso we suggest two real time indices bsiso1 and bsiso2 based on multivariate empirical orthogonal function mv eof analysis of daily anomalies of outgoing longwave radiation olr and zonal wind at 850 hpa u850 in the region 10 s 40 n 40 160 e for the extended boreal summer may october season over the 30 year period 1981 2010 bsiso1 is defined by the first two principal components pcs of the mv eof analysis which together represent the canonical northward propagating variability that often occurs in conjunction with the eastward mjo with quasi oscillating periods of 30 60 days bsiso2 is defined by the third and fourth pcs which together mainly capture the northward northwestward propagating variability with periods of 10 30 days during primarily the pre monsoon and monsoon onset season the bsiso1 circulation cells are more rossby wave like with a northwest to southeast slope whereas the circulation associated with bsiso2 is more elongated and front like with a southwest to northeast slope bsiso2 is shown to modulate the timing of the onset of indian and south china sea monsoons together the two bsiso indices are capable of describing a large fraction of the total intraseasonal variability in the asm region and better represent the northward and northwestward propagation than the real time multivariate mjo rmm index of wheeler and hendon

magnetic susceptibility evidence of monsoon variation on the loess plateau of central china during the last 130 000 years the magnetic susceptibility of loess and paleosols in central china represents a proxy climate index closely related to past changes of precipitation and vegetation and thus to summer monsoon intensity time series of magnetic susceptibility constructed for three loess paleosol sequences in the southern part of the chinese loess plateau document the history of summer monsoon variation during the last 130 000 yr they correlate closely with the oxygen isotope record of stages 1 to 5 in deep sea sediments soils were forming during intervals of strong summer monsoon whereas loess units were deposited at times of reduced monsoon intensity the chinese loess paleosol sequence can thus be viewed as a proxy record of asian monsoon variability extending over the last 2 5 myr

northwestward propagation of the intraseasonal oscillation in the western north pacific during the boreal summer structure and mechanism abstract the convection of the intraseasonal timescale in the western north pacific during the boreal summer tends to propagate northwestward in the philippine sea to near 20 n and then continues propagating westward the formation of enhanced convection in the western north pacific is a result of the merging of a convective system moving eastward along the equator and a westward propagating low level convergence anomaly which is located to the east of a vortex in the subtropics a positive feedback between the anomalous circulation and convection leads to a rapid enhancement of the system the strengthened southwesterly associated with the vortex enhances evaporation over the oceans e g the eastern indian ocean the bay of bengal and the south china sea and transports moisture northeastward the moisture converges at the northwestern corner of the convection and results in a potentially unstable atmosphere the result is the northwestward propagation of the coupled circulation convection system in

provenance of the north pacific sediments and process of source material transport as derived from rb sr isotopic systematics abstract rb sr isotopic systematics of 111 samples of sediments in nine cores from the north pacific of quaternary and pliocene ages have been investigated they provide information on the provenance the process of particle transport and temporal variation in the flux of source material the rb sr isotopic systematics of the core sediments show well correlated pseudo isochrons the pseudo isochrons reflect the mixing of two types of material i e the asian continental material with high 87 rb 86 sr ratios 4 5 6 5 and high 87 sr 86 sr ratios 0 723 0 727 and the volcanic material with low 87 rb 86 sr ratios and low 87 sr 86 sr ratios from island arc volcanics such as the izu ogasawara mariana and the japanese islands and oceanic islands such as the hawaiian islands 0 0 2 0 0 703 0 708 the clearness of the pseudo isochrons implies that the rb sr isotopic composition of the weathering products derived from the asian continental crust is extremely homogenized the fine fraction a few m with a high 87 rb 86 sr ratio 5 0 6 5 is widely transported into the north pacific by the middle latitude westerlies and contributes largely to pelagic sediments the coarser fraction with a lower 87 rb 86 sr ratio

a mineral tracer toward high resolution dust provenance on the chinese loess plateau sem tem and sulfur isotopes of sulfate inclusions in biotite the most important terrestrial archive of the quaternary climate is the chinese loess plateau clp distributed over a vast region peripheral to the deserts of inner asia numerous paleoclimatic studies have examined magnetic chemical and isotopic proxies from deep loess paleosol sections however the highly uniform mineralogy of the clp has made it difficult to track the provenance transportation and deposition of dust particles here we report that the micrometer scale mineralogical heterogeneity of the loess particles has a significant potential in determining high resolution loess provenance scanning and transmission electron microscopy of the chinese loess reveals that biotite particles commonly have microinclusions of ba sr sulfates displacing the micaceous layers along cleavages chemical compositions varied widely from barite to celestine within the same biotite grain the ba rich sulfates precipitated first followed by an overgrowth of sr rich sulfates the frequency of sulfate bearing biotite varied greatly over several loess sections implying a specific source and sedimentation process their abundance on the western clp and sulfur isotopic composition support their derivation from porous sedimentary sequences reacted with hypersaline solutions e g arkosic sandstone probably located west of the clp covering the qilian mountains qaidam basin and surrounding mountains of the tibetan qinghai plateau the sulfate bearing biotite is the first microscopic mineral tracer in the clp provoking further search for other microscopic heterogeneities of the chinese loess and their equivalents in the source regions

changes in mineralogy of loess paleosol sections across the chinese loess plateau quantitative mineralogical analysis of bulk samples and single particles was carried out on three loess sections of different local climate settings on the chinese loess plateau clp mineralogy geochemistry and single particle petrography of loess and paleosols are relatively uniform over the clp however in detail there are mineralogical changes related to eolian process and chemical weathering particle size sorting eastward from western sources led to an eastward increase of the total phyllosilicate contents enriched in fine illitic clay minerals after deposition detrital minerals susceptible to chemical weathering were sequentially altered in a progressive fashion with increasing precipitation in the order of calcite dolomite biotite illite chlorite amphibole and plagioclase the weathering of biotite chlorite and illite resulted in a significant increase of expandable phyllosilicate contents the sequential weathering of the minerals is reflected chemically in the decrease of na and mg and the increase of iron oxidation mineralogy of the chinese loess at individual sites reflects the effects of size fractionation during eolian transportation and progressive sequential weathering along the climatic gradient and it is essential to consider both effects when using mineralogical and dependent chemical data in the paleoclimatic reconstruction of the clp

pedosedimentary development and palaeoenvironmental significance of the s1 palaeosol on the northeastern margin of the qinghai xizang tibetan plateau the s1 pedocomplex correlated to oxygen isotope stage 5 of the ocean cores has been traced west of the loess plateau on to the extreme northeastern margin of the qinghai xizang tibetan plateau in china detailed micromorphological analysis of closely spaced thinsections from the pedocomplex at this site provides the basis for reconstruction of the sequence of pedosedimentary processes and associated palaeoenvironmental changes occurring during this time interval the six pedosedimentary stages identified are interpreted in terms of temporal variations in depositional rates size of particles transported and availability of moisture for pedogenic alteration as determined by changing balances in dominance of winter and summer monsoonal forces two main soil forming intervals are identified the more extensive of the two in terms of resultant pedological features reflects pedogenic alteration at a relatively stable land surface under a semi arid climate during the later part of pedosedimentary stage 2 the other main period corresponds to pedosedimentary stages 4 and 5 when leaching and bioturbation processes were active at aggrading surfaces leading to development of an accretionary unit without clear differentiation of horizons pedosedimentary stages 1 3 and 6 were characterised mainly by rapid rates of coarse loess accumulation with synsedimentary modification restricted to surface slaking and crust formation and minor localised redistribution of calcite

asian dustfall in the st elias mountains yukon canada in april 2001 a major atmospheric dustfall event occurred in the st elias mountains yukon territory canada field samples were collected and analyzed for particle size mineralogy chemical composition and sr nd and pb isotopes dusts found above 3000 m had their source in the gobi desert region of northern china and inner mongolia and were transported to the yukon following a series of major dust storms that took place in early april dusts found below 3000 m had local yukon or mixed source s the asian dusts had a modal volume diameter of 4 m typical of far traveled mineral aerosols however larger 10 m particles were also found at 5000 m suggesting a very rapid trans pacific transport in the mid troposphere we estimate that the april 2001 event deposited from 5500 to 6335 tons of dust over an area of 21 000 km2 in the southwestern yukon most of which probably fell within a week our findings are consistent with instrumental observations and model simulations of the april 2001 event while the dust cloud was reportedly mixed with volatile pollutants from asia we found no evidence of metal pollution associated with the dustfall in the yukon our findings contribute to clarify the dynamics and the geochemical impact of asian dust long range transport events and to better estimate eolian fluxes of dustborne elements e g fe to the ocean associated with such events they may also assist in identifying past asian dust events in ice cores drilled from the st elias mountains icefields to develop a long term record of their frequency magnitude and source s

low frequency equatorial waves in vertically sheared zonal flow part i stable waves abstract the mechanism by which a vertically sheared zonal flow affects large scale low frequency equatorial waves is investigated with two level equatorial plane and spherical coordinates models vertical shears couple barolinic and barotropic components of equatorial wave motion affecting significantly the rossby wave and westward propagating yanai wave but not the kelvin wave this difference results from the fact that the barotropic component is a modified rossby mode and can be resonantly excited only by westward propagating internal waves the barotropic components emanate poleward into the extratropics with a pronounced amplitude while the baroclinic components remain equatorially trapped a westerly vertical shear favors the trapping of rossby and yanai waves in the upper troposphere whereas an easterly shear tends to confine them in the lower troposphere as such their westward propagation is slowed down by both westerly and easterly shears when the strength of the vertical shear varies w

pacific east asian teleconnection how does enso affect east asian climate observational evidence is presented to show a teleconnection between the central pacific and east asia during the extreme phases of enso cycles this pacific east asian teleconnection is confined to the lower troposphere the key system that bridges the warm cold events in the eastern pacific and the weak strong east asian winter monsoons is an anomalous lower tropospheric anticyclone cyclone located in the western north pacific the western north pacific wind anomalies develop rapidly in late fall of the year when a strong warm or cold event matures the anomalies persist until the following spring or early summer causing anomalously wet dry conditions along the east asian polar front stretching from southern china northeastward to the east of japan kuroshio extension using atmospheric general circulation and intermediate models the authors show that the anomalous philippine sea anticyclone results from a rossby wave response to suppressed convective heating which is induced by both the in situ ocean surface cooling and the subsidence forced remotely by the central pacific warming the development of the anticyclone is nearly concurrent with the enhancement of the local sea surface cooling both the anticyclone and the cooling region propagate slowly eastward the development and persistence of the teleconnection is primarily attributed to a positive thermodynamic feedback between the anticyclone and the sea surface cooling in the presence of mean northeasterly trades the rapid establishment of the philippine sea wind and sst anomalies implies the occurrence of extratropical tropical interactions through cold surge induced exchanges of surface buoyancy flux the central pacific warming plays an essential role in the development of the western pacific cooling and the wind anomalies by setting up a favorable environment for the anticyclone sst interaction and midlatitude tropical interaction in the western north pacific

rb sr and k ar systems of biotite in surface environments regulated by weathering processes with implications for isotopic dating and hydrological cycles of sr isotopes abstract biotite is widely used for rb sr and k ar isotopic dating and influences sr isotope geochemistry of hydrological regimes the isotopic system of biotite behaves diversely in response to surface weathering i e the complete preservation of original rb sr and k ar isotopic ages or dramatic reduction in this study we have explored the relation between the behavior of isotopic systems and complex weathering processes of biotites in the weathering profiles distributed on the mesozoic granitoids in south korea in the lower parts of the profiles biotite in the early stages of weathering was transformed into either oxidized biotite or hydrobiotite with a mass release of 87 sr and 40 ar forced by the rapid oxidation of ferrous iron during the transformation to oxidized biotite 87 sr and 40 ar were preferentially released relative to rb and k respectively via solid state diffusion through the biotite lattice resulting in a drastic reduction of original isotopic age the reduction of rb sr age was greater than that of k ar age because k was preferentially released over rb whereas 87 sr and 40 ar were released proportionally to each other however during the transformation of biotite to hydrobiotite i e to regularly interstratified biotite vermiculite 87 sr rb 40 ar and k were completely retained in the alternating biotite interlayer and thus the original isotopic age can be preserved in the upper parts of the profiles where iron oxidation was almost completed 87 sr rb 40 ar and k were gradually and proportionally released with no further significant change in isotopic age during the gradual transformation of the early formed oxidized biotite into hydrobiotite and vermiculite or during their final decomposition to kaolinite the ratios and amounts of isotopes released from weathered biotites are dependent upon the degree of iron oxidation and the pathways of mineralogical transformation regional and local variations in isotopic systems affected by particular weathering processes should be considered when dating biotite or biotite bearing rocks in weathering environments modeling the transfer of sr isotopes to hydrologic regimes and tracking the provenance of sediments

boreal summer intraseasonal phases identified by nonlinear multivariate empirical orthogonal function based self organizing map esom analysis abstractthis study develops an empirical orthogonal function eof based self organizing map som esom analysis to identify the nonlinear characteristics of the boreal summer intraseasonal oscillation bsiso which involves interactions between the summer mean circulation and the convectively coupled equatorial waves which make bsiso evolution more complex than the madden julian oscillation the method utilizes the first five principal components of the outgoing longwave radiation olr and the zonal wind at 850 hpa u850 and has the advantages of filtering out uncertainties from noise and being free from mathematical restrictions such as orthogonality and linearity the esom analysis enables the detection of bsiso over the asian summer monsoon region with eight phases the four most distinguishable phases represent 1 a pair of stationary patterns with a dipole between the eastern indian ocean and the philippine sea phases 1 and 5 and 2 a pair of propagating patterns with a northwest southeast t

an interdecadal change in the relationship between the western north pacific ocean and the east asian summer monsoon this study reveals that the relationship between the western north pacific ocean wnpo 0 55 n 100 165 e and the east asian summer monsoon easm experiences a well defined interdecadal change in the late 1980s and early 1990s the easm related wnpo sea surface temperature anomaly ssta pattern changes from the dipole pattern wnpo dipole wnpod that develops over the period between 1968 and 1987 p1 to a tripole pattern wnpo tripole wnpot between 1991 and 2010 p2 the positive negative phase of the wnpod is characterized by warm cold sstas in the japan sea and kuroshio oyashio extension region and cold warm sstas in the subtropical wnpo whereas the positive negative phase of the wnpot shows warming cooling in the kuroshio extension region ker and cooling warming in the south of kamchatka peninsula skp and philippine sea ps during p1 p2 the wnpod wnpot can be regarded as the first second leading mode of summer wnpo sst variability and its positive phase is associated with a weakened wnpo subtropical high and thereby the deficient summer rainfall in the yangtze river valley together with a strong easm and vice versa the change in the wnpo easm relationship may be caused by interdecadal changes in the relationship of the equatorial central pacific ecp with the wnpo and easm and an increase in summer ker sst variability during p2 because the ecp warming induced cyclonic anomalies move northwestwards and intensify summertime ecp warming is able to generate a strong easm and significant cooling over the two poles of the wnpot skp and ps these strengthened impacts of the ecp on the wnpot and easm contribute to the strengthened wnpot easm relationship during p2 in addition summer ker sst variability increases between 1991 and 2010 and this may have enhanced the impact of the ker on the easm during p2 these two factors probably cause the easm related wnpo ssta pattern to change from the wnpod in p1 to the wnpot in p2

the nature origin and accumulation of loess abstract loess can be defined simply as a terrestrial clastic sediment composed predominantly of silt size particles which is formed essentially by the accumulation of wind blown dust there are three fundamental requirements for its formation 1 a sustained source of dust 2 adequate wind energy to transport the dust and 3 a suitable accumulation site most loess has been modified to some degree by local reworking bioturbation and syn depositional weathering but a process of loessification is not necessary for a dust deposit to qualify as loess the terms primary loess and secondary loess have previously been used to described wind deposited loess and redeposited loess respectively but it is more accurate to describe material reworked and redeposited by non aeolian processes as loess derived colluvium or loess derived alluvium during the quaternary loess formed in three main situations 1 mid continental shield areas beyond the limits of ice sheets periglacial loess 2 on the margins of high mountain ranges perimontane loess and 3 on the semi arid margins of some lowland deserts peridesert loess peridesert loess is relatively poorly developed partly due to the limited efficiency of silt generating mechanisms in low land deserts compared with glaciation but also important is the tendency in arid areas for dust to be dispersed over a wide area and to be rapidly reworked after deposition particularly in areas which experience frequent climatic changes the remarkably thick loess of china and central asia results from an unusual combination of conditions which has persisted for much of the last 2 3 million years namely rapid uplift of the tibetan plateau and surrounding mountain ranges high rates of sediment production and supply to adjacent basins a strong northwesterly and westerly wind regime and the existence of effective dust traps downwind of the source regions

structures and mechanisms of the northward propagating boreal summer intraseasonal oscillation abstract the spatial and temporal structures of the northward propagating boreal summer intraseasonal oscillation bsiso are revealed based on the analysis of both the echam4 model simulation and the ncep ncar reanalysis the bsiso structure and evolution characteristics simulated by the model bear many similarities to those derived from the ncep ncar reanalysis the most notable features are the remarkable meridional asymmetries relative to the bsiso convection in the vorticity and specific humidity fields a positive vorticity perturbation with an equivalent barotropic structure appears a few latitude degrees north of the convection center the maximum specific humidity also shows a clear northward shift in the lower troposphere two internal atmospheric dynamics mechanisms are proposed to understand the cause of the northward propagation of the bsiso the first is the vertical shear mechanism the key process associated with this mechanism is the generation of barotropic vorticity due to the couplin

enso like interdecadal variability 1900 93 a number of recent studies have reported an enso like eof mode in the global sea surface temperature sst field whose time variability is marked by an abrupt change toward a warmer tropical eastern pacific and a colder extratropical central north pacific in 1976 77 the present study compares this pattern with the structure of the interannual variability associated with the enso cycle and documents its time history back to 1900 the analysis is primarily based on the leading eofs of the sst anomaly and anomaly deviation fields in various domains and the associated expansion coefficient or principal component time series which are used to construct global regression maps of sst sea level pressure slp and a number of related variables the use of anomaly deviations i e departures of local sst anomalies from the concurrent global mean sst anomaly reduces the influence of global mean sst trends upon the structure of the eofs and their expansion coefficient time series an important auxiliary time series used in this study is a southern oscillation index based on marine surface observations by means of several different analysis techniques the time variability of the leading eof of the global sst field is separated into two components one identified with the enso cycle related variability on the interannual timescale and the other a linearly independent residual comprising all the interdecadal variability in the record the two components exhibit rather similar spatial signatures in the global sst slp and wind stress fields the sst signature in the residual variability is less equatorially confined in the eastern pacific and it is relatively more prominent over the extratropical north pacific the corresponding slp signature is also stronger over the extratropical north pacific and its counterpart in the cold season 500 mb height field more closely resembles the pna pattern the amplitude time series of the enso like pattern in the residual variability reflects the above mentioned shift in 1976 77 as well as a number of other prominent features including a shift of opposite polarity during the 1940s

enhanced relationship between the tropical atlantic sst and the summertime western north pacific subtropical high after the early 1980s the western north pacific subtropical high wnpsh in boreal summer shows a remarkable enhancement after the early 1980s whereas the sea surface temperature sst in the north indian ocean nio and the equatorial eastern pacific had been noted to have remarkable local or remote effects on enhancing the wnpsh the influence of the atlantic sst so far is hardly explored this article reports a new finding enhanced relationship between the tropical atlantic ta sst and the wnpsh after the early 1980s regression study suggests that the warm ta sst produced a zonally overturning circulation anomaly with descending over the equatorial central pacific and ascending over the tropical atlantic eastern pacific the anomalous descending over the equatorial central pacific likely induced low level anticyclonic anomaly to the west and therefore enhanced the wnpsh one implication of this new finding is for predictability the well known spring predictability barrier i e the influence of el nino southern oscillation enso falls dramatically during boreal spring does not apply to the ta sst wnpsh relationship the ta sst shows consistently high correlation starting from boreal spring when the enso influence continues declining the ta sst extends the predictability of the wnpsh in boreal summer approximately one season earlier to boreal spring

deposition and weathering of asian dust in paleolithic sites korea abstract paleolithic stone artifacts in korea typically occur in brown clay silt bcs sequences the origin and depositional environment of these sequences are important for reconstructing the paleoenvironment as well as for establishing chronologies of artifact bearing stratigraphic units we investigated four bcs bearing sections in foothills and river and marine terraces in korea by applying quantitative mineralogical geochemical microtextural and k ar isotopic methods in all four sections the lower units are colluvial and fluvial deposits strongly influenced by diverse local lithology whereas the upper units are characterized by bcs units mineralogical geochemical compositions grain sizes and colors converge into common properties in the upper bcs units in all sections these common properties are consistent with the eastward trends of increasing weathering degree and grain size fining throughout the loess paleosol sections of the chinese loess plateau clp k ar detrital ages of the sections also converge upward into a narrow range similar to the age ranges of the loess and paleosols in the clp the top bcs unit in the jeongok section the thickest section is underlain by an additionally weathered bcs unit with strong red chroma indicating a change from warm to cold climate we did not observe any clear evidence of climatic changes in other thinner sections which may be due to a superposition of cold stage accumulation and warm stage deep weathering the common properties of the bcss in korean sections and their relationship to the clp loess and paleosols indicate widespread deposition of asian dust and subsequent weathering in the late quaternary forming bcs sequences in this respect the bcs sequences investigated here are considered to be the additionally weathered equivalents of the clp loess paleosol sequences having been exposed to the high annual precipitation of the korean peninsula given the wide distribution of bcs sequences at paleolithic sites throughout the peninsula the findings of this study are important for the ongoing debate surrounding the depositional environments of the paleolithic deposits and provide a foundation for the establishment of the chronological framework of the paleolithic artifact bearing layers and lithic assemblages

interdecadal variability of summer climate over east asia and its association with 500 hpa height and global sea surface temperature interdecadal variability of summer climate rainfall and temperature in east asia china and japan and its association with the anomalies of geopotential heights at 500 hpa over the northern hemisphere nh global sea surface temperature ssta and outgoing longwave radiation olr were examined an abrupt change was found in the middle and by the end of the 1970s in the variations of time coefficients of the second mode of singular value decomposition svd2 for the summer rainfall and temperature in china the rainfall anomaly around 1977 1979 changes from above normal to below normal and the temperature changes from below normal to above normal in the southern and southwestern parts of china a similar interdecadal variability was also found in the summer climate variations in the southwest islands of japan the 500 hpa height anomalies related to the spatial pattern of svd2 shows a clear dipole pattern the negative center is located in mongolia and northeastern china and the positive center is located in middle and southern china the abrupt change of summer climate in the middle and by the end of the 1970s over the subtropical regions of east asia is characterized with the intensification and westward and southward extension of the western pacific subtropical high wpsh it is also observed in geopotential height variations over eurasia around 1977 1978 an abrupt change of sst over the tropical indian ocean and tropical western pacific was also found around 1976 1977 it is indicated that interdecadal variability of summer rainfall and temperature over east asia is largely influenced by the change of ssta and convective activity in the tropical indian ocean and tropical western pacific the convective activity over the tropical indian ocean and tropical western pacific is usually enhanced when the sst is warmer than normal so the subtropical high anomalies over the subtropical regions of east asia are intensified through the enhancement of a hadley cell as a result the subtropical regions of east asia including southern and southwestern china and the southwest islands of japan are covered by a positive height anomaly at 500 hpa where the temperature is above normal and the rainfall is below normal

20 50 day oscillation of summer yangtze rainfall in response to intraseasonal variations in the subtropical high over the western north pacific and south china sea the spatio temporal variability in summer rainfall within eastern china is identified based on empirical orthogonal function eof analysis of daily rain gauge precipitation data for the period 1979 2003 spatial coherence of rainfall is found in the yangtze basin and a wavelet transform is applied to the corresponding principal component to capture the intraseasonal oscillation iso of yangtze rainfall the ensemble mean wavelet spectrum representing statistically significant intraseasonal variability shows a predominant oscillation in summer yangtze rainfall with a period of 20 50 days a 10 20 day oscillation is pronounced during june and july this finding suggests that the 20 50 day oscillation is a major agent in regulating summer yangtze rainfall composite analyses reveal that the 20 50 day oscillation of summer yangtze rainfall arises in response to intraseasonal variations in the western north pacific subtropical high wnpsh which in turn is modulated by a rossby wave like coupled circulation convection system that propagates northward and northwestward from the equatorial western pacific when an anomalous cyclone associated with this rossby wave like system reaches the south china sea scs and philippine sea the wnpsh retreats northeastward due to a reduction in local pressure under these conditions strong monsoonal southwesterlies blow mainly toward the scs philippine sea while dry conditions form in the yangtze basin with a pronounced divergent flow pattern in contrast the movement of an anomalous anticyclone over the scs philippine sea results in the southwestward extension of the wnpsh consequently the tropical monsoonal southwesterlies veer to the northeast over the scs and then converge toward the yangtze basin producing wet conditions therefore the 20 50 day oscillation of yangtze rainfall is also manifest as a seesaw pattern in convective anomalies between the yangtze basin and the scs philippine sea a considerable zonal shift in the wnpsh is associated with extreme dry wet episodes in the yangtze basin with an abrupt eastward westward shift in the wnpsh generally leading the extreme negative positive yangtze rainfall anomaly by a 3 8 period of the 20 50 day oscillation this finding may have implications for improving extended range weather forecasting in the yangtze basin

contrasting lipid biomarker composition of terrestrial organic matter exported from across the eurasian arctic by the five great russian arctic rivers contrasting lipid biomarker composition of terrestrial organic matter exported from across the eurasian arctic by the five great russian arctic rivers

chinese loess record of monsoon climate during the last glacial interglacial cycle the thick loess paleosol succession of central china contains a detailed record of changes in east asian monsoon climate since the late miocene epoch the alternating loess paleosol stratigraphy closely resembles the marine oxygen isotope record implying that episodic dust deposition and pedogenesis are in phase with global ice volume fluctuations and controlled by variations in solar radiation reaching the land surface deposits equivalent to marine isotope stages mis 5 through 1 have been dated by 14c 10be luminescence and magnetic susceptibility and grain size models malan loess mis 4 2 decreases in thickness southeastward from 30 m in the western loess plateau to 5 m east of xi an downwind asian dust is found in japan the north pacific ocean and the greenland ice sheet where it has a chemical signature that points to a primary source in western china during glacial times the mean dust flux in the central loess plateau reached 0 35 mm year whereas in interglacial times it fell to 0 1 mm year times of high dust influx and reduced soil development coincided with strengthened winter monsoon conditions which are inferred from variations in loess grain size times of decreased dust accumulation and strong pedogenesis marked by high values of magnetic susceptibility represent times of strengthened summer monsoon conditions high frequency fluctuations in dust influx during deposition of the malan loess include peaks that likely correlate with north atlantic heinrich events the younger dryas oscillation is recorded in chinese eolian and organic deposits by a shift from cool humid late glacial conditions to cold and dry conditions followed by a return to milder humid climate at the beginning of the holocene warm moist climate associated with a strong summer monsoon characterized the first half of the holocene epoch when a widespread paleosol complex developed on the loess plateau increased dust deposition during the middle to late holocene marked a shift to cooler drier conditions

geochemistry of quaternary sediments of the jeongokri archaeological site korea implications for provenance and palaeoenvironments during the late pleistocene the geochemical characteristics of an approximately 6 m long sediment core collected from the jeongokri archaeological site hantan river korea were examined to determine the provenance of the sediments and to reconstruct the palaeoenvironment of the study area during the late pleistocene 200 127 ka the core sediments were subdivided into two parts based on grain size an upper 0 380 cm depth and lower part 380 cm depth the lower part was deposited primarily by fluvial processes during an interglacial period marine isotope stage mis 7 with warm and humid conditions conversely the upper part was mainly deposited by aeolian processes during a cold and dry glacial period mis 6 geochemical characteristics represented by major trace and rare earth element ree compositions and textures of the jeongokri core sediments show distinct differences between the upper and lower parts the mineralogy and major trace and ree compositions indicate that the influence of felsic source rocks e g granite was dominant in the lower sediments which were derived from the hantan river in contrast increased quartz content and the very fine and homogeneous grain size in the upper sediments indicate an aeolian origin ree ratios and distribution patterns and geochemical signatures indicate that these sediments were derived predominantly from chinese loess deposits and partially from local sediments from the korean peninsula the possible source area of the upper sediments is the northern part of the yellow sea basin the yellow sea basin having mixed geochemical signatures between chinese loess and korean derived sediments was exposed because of low sea levels during mis 6 the exposed yellow sea basin was located in the path of winter monsoon winds which may have carried a great deal of airborne sediments from the basin to the jeongokri area copyright 2011 john wiley sons ltd

bite profiles of some benthic grab samplers abstract the bite profiles of six 0 1 m 2 benthic grab samplers were reconstructed from video recordings of closure the petersen and the chain rigged van veen grabs both took shallow bites of variable profile the day and the smith mcintyre grabs both took fairly deep and consistent bites but were prevented by their frames from using their momentum on landing to increase penetration two designs of warp rigged van veen grab both took deep parallel sided bites the long arm warp rigged van veen was the only grab to collect sediment from a depth of at least 50 mm over the entire 0 1 m 2 sampled a bucket shape designed to optimise penetration and minimise upwards movement on closure is suggested

interdecadal change in the relationship between enso and the intraseasonal oscillation in east asia abstract the northward propagating intraseasonal oscillation npiso during the boreal summer is closely linked to the onset retreat and intensity of the east asian summer monsoon easm in this study interdecadal variability in the relationships between the npiso and el nino southern oscillation enso was investigated using long term outgoing longwave radiation data obtained from the 40 yr ecmwf re analysis era 40 for a 44 yr period 1958 to 2001 it was found that before the late 1970s the preceding winter enso influenced the early summer i e may to june npiso activity whereas after the late 1970s a strong relationship appeared during the later summertime i e july to august the may june npiso before the late 1970s was modulated by springtime indian ocean sea surface temperature warming and central north pacific suppressed convection anomalies and was consequently related to the enso induced west pacific wp pattern which shows a north south dipole structure over the north pacific from

relationship between enso and northward propagating intraseasonal oscillation in the east asian summer monsoon system 1 observational studies are presented on the relationship between el nino southern oscillation enso and the northward propagating intraseasonal oscillation npiso in the east asian summer monsoon easm system the summer npiso activity shows a significant correlation with the preceding winter extreme phase of enso cycles a higher correlation appears during late summer which is consistent with frequent heavy rainfall events at that time as revealed in some previous case studies the westward expansion of broad anticyclonic circulation over the western north pacific and the smaller cyclonic circulation around korea and japan are found to be associated with the npiso activity enso affects the late summer npiso activity through an atmospheric bridge and wave propagation the springtime indian ocean sea surface temperature warming induced by enso through the walker circulation leads to the downward motion and suppressed convection over the philippine sea and this generates the forced rossby wave train forming the above south to north low level circulation anomalies

a new upper level circulation index for the east asian summer monsoon variability the east asian summer monsoon easm andits variability involvecirculationsystems in both the tropicsand midlatitudes as well as in both the lower and upper troposphere considering this fact a new easm index newi is proposed based on 200 hpa zonal wind which takes into account wind anomalies in the southern about 58n middle about 208n and northern areas about 358n of east asia the newi can capture the interannual easm related climate anomalies and the interdecadal variability well compared to previous indices thenewishowsabetterperformanceindescribingprecipitationandairtemperaturevariationsovereastasia it can also show distinct climate anomalous features in early and late summer the newi is tightly associated with the east asian pacific or the pacific japan teleconnection suggesting a possible role of internal dynamics in the easm variability meanwhile the newi is significantly linked to el nino southern oscillation and tropical indian ocean sea surface temperature anomalies furthermore the newi is highly predictable in the ensembles models indicating its advantage for operational prediction of the easm the physical mechanism of the easm variability as represented by the newi is also explicit both warm advection anomalies of temperaturebyanomalouswesterlywindsandtheadvectionofanomalouspositiverelativevorticitybynortherly basic winds cause anomalous ascending motion over the mei yu changma baiu rainfall area and vice versa over the south china sea area hence this newi would be a good choice to study monitor and predict the easm

iron geochemistry of loess and red clay deposits in the chinese loess plateau and implications for long term asian monsoon evolution in the last 7 0 ma abstract recently some groups of authors have demonstrated that the tertiary red clay deposits underlying the pleistocene loess paleosol sequence in the chinese loess plateau are wind blown in origin thus extending the eolian record in the plateau from 2 6 ma back to about 7 0 ma and providing a good opportunity to reconstruct long term monsoon changes as magnetic susceptibility the widely used paleomonsoon proxy of loess deposits is problematic in reconstructing the monsoon history recorded in the red clay the development of other proxies is urgently needed in this study we analyzed the ratios of citrate bicarbonate dithionite cbd extractable fe2o3 to total fe2o3 concentrations in four loess sections along a north south transect of the loess plateau and in the lingtai loess red clay sequence of 305 m thick the fe2o3 ratio in the loess sections clearly shows higher values in soil units than in loess horizons and a southward increase in this ratio is also remarkable along the transect these are in good agreement with the temporal spatial variations in the east asia summer monsoon intensity identified by other monsoon proxies and soil development observations the fe2o3 ratio thus attests to being a good proxy indicator of the summer monsoon evolution the lingtai fe2o3 ratio record shows high values over three time intervals 4 8 4 1 ma 3 4 2 6 ma and during the interglacial periods of the past 0 8 ma the increase in summer monsoon intensity over the three intervals also coincides with the well developed soil characteristics it is therefore concluded that the east asia summer monsoon has experienced a non linear evolution since the late miocene the occurrence of a monsoon prime at about 4 8 4 1 ma implies that the tibetan plateau one of the most important boundary conditions in maintaining the monsoon circulation must have been uplifted to a critical height at that time

mechanisms of monsoon low frequency variability surface hydrological effects abstract observations indicate that monsoon systems are characterized by orderly large scale and low frequency variations with a time scale of two weeks and sometimes longer regions of ascending motion are observed to form to the north of the equator and propagate slowly northward across southeast asia the propagation appears to be associated with the active break sequence of the summer monsoon which acts as a modulator on the activity of the synoptic scale disturbances a zonally symmetric non linear two layer model containing an interactive ocean and a continent poleward of 18 n is used to investigate the mechanisms which produce the observed low frequency variability only when a full hydrology cycle is considered does the model product variations which resemble the observed structures mechanisms are traced to include the interaction of the components of the total heating function the sensible heat input in the boundary layer although considerably smaller than the other heating components de

the eolian origin of silty mantle in sedentary soils from korea and japan abstract the concentration particle size distribution and oxygen isotope composition 18 o smow of quartz were examined in order to determine the extent to which the accretion of long distance eolian dusts from the interior of china had formed the sedentary soils overlying diverse parent materials in korea and japan the quartz content of the surface soils developed on quartz free basaltic materials varies from 8 9 to 47 7 generally the soil quartz found in surface horizons is finer than of the subsurface horizons and or substrata the particle size of the soil quartz decreases from the west coast to eastern coastal margins of korea and to the japanese islands this follows the major trajectory of westerly winds which carry the eolian dusts from the interior of china to mid latitude regions of the north pacific the oxygen isotope composition of the fine quartz 1 10 m in diameter when separated from surface and subsurface horizons is found in a relatively narrow range of 15 9 to 17 7 the values are indiscernible from those of recent eolian dusts from the interior desert and loess plateau of china the 18 o values from the same sized quartz found in c horizons 10 4 and 19 2 consisting of saprolitic andesites and shales respectively differ from those of the overlying soils the 18 o values of soil quartz developed on igneous materials systematically decrease with increasing particle size to 53 m 14 they abruptly decrease to 8 to 12 for fractions larger than 53 m a large apparent oxygen isotope fractionation up to 10 between fine 17 and coarse 8 to 12 grained quartz observed in the samples does not represent an equilibrium oxygen isotope fractionation for normal magmatic processes the data provide evidence for an eolian origin of the fine quartz incorporated during soil development

bulk and single particle mineralogy of asian dust and a comparison with its source soils 1 the mineralogical properties of asian dust have been examined in detail and the results have been compared with the chinese source soils using high resolution scanning electron microscopy transmission electron microscopy x ray diffraction and chemical analysis mineralogical classification of asian dust particles showed that the most common single particles were clay aggregates 48 that were often mixed with nanosized calcite followed by particles of quartz 22 plagioclase 11 coarse calcite 6 k feldspar 5 muscovite chlorite kaolinite amphibole gypsum fe and ti oxides which were either partly or entirely attached with clay size mineral grains the clay minerals in asian dust were mostly illite and interstratified illite smectite the average mineral composition of the bulk dust samples by x ray diffraction was quartz 28 plagioclase 11 k feldspar 8 calcite 8 illite 19 interstratified illite smectite 22 chlorite 2 smectite 1 and kaolinite 1 in the silty soils from the source regions the clay minerals and nanosized pedogenic calcite aggregated and covered silt size minerals while the sands were mostly composed of quartz and feldspars and were lined with clay minerals the mineralogy of asian dust was similar to that of the silty soil from the loess plateau but the total phyllosilicate content increased from desert sands 7 silty soil 23 to asian dust 45 fining eastward the optical properties of asian dust and its interaction with atmospheric gases and cloud are probably affected by the clay rich mineral composition the aggregation and attachment of the clay minerals on the coarser minerals and the nanosized calcite

east west sst contrast over the tropical oceans and the post el nino western north pacific summer monsoon 1 the circulation and sst anomalies during the post el nino asian summer monsoon season were examined through data analysis and linear equatorial plane model calculations over the philippine sea a negative precipitation anomaly and low level anti cyclonic anomaly were found over the western equatorial pacific a low level easterly anomaly prevailed an east west sst anomaly contrast dominated over the tropical indian and pacific oceans with positive anomalies over the indian and western pacific oceans and negative anomalies over the central to eastern pacific the plane model demonstrated that the anti cyclonic anomaly over the philippine sea was a rossby response to the negative precipitation anomaly found in this region the easterly anomaly along the equator was part of a kelvin response to the sst anomaly contrast on the northern side of this anomalous easterly a negative vorticity anomaly developed this could induce the moist rossby wave over the philippine sea

interbasin coupling between the tropical indian and pacific ocean on interannual timescale observation and cmip5 reproduction the interaction of el nino southern oscillation enso with tropical indian ocean s two major modes i e indian ocean dipole iod and indian ocean basinwide mode iobm is of great importance to understanding global climate variability using observational data for the last 50 years and the phase five of coupled model intercomparison project cmip5 historical simulation for the last 100 years this study investigates the role of interbasin coupling between the indian and pacific ocean on el nino evolution analyses suggest that the combined effect of the iod during the developing el nino phase and the iobm during the decaying phase plays a critical role in leading a fast transition from el nino to la nina in particular a faster iod termination and predominant iobm in the el nino winter result in prevailing easterly wind anomalies through the eastern indian ocean to the western pacific countervailing the iod related westerly wind anomalies over the western pacific the significant easterly wind anomalies then contribute to the maintenance of the western north pacific subtropical high anomalies until the el nino decaying summer consequently facilitating rapid termination of el nino and transition to la nina meanwhile the sole effect of either iod or iobm causes a slow decay of el nino the 20 cmip5 models generally capture the role of interbasin coupling on the el nino evolution in spite of models common deficiencies in simulating the easterly wind anomalies after decay of iod the late iod demise might cause weaker el nino phase transition in models due to the longer lasting destructive interference between iod and iobm related western pacific wind anomalies this study indicates that challenges still remain in better simulations of the various aspects of interbasin indo pacific coupling and then a diversity of the enso life cycle

interdecadal changes in the major modes of asian australian monsoon variability strengthening relationship with enso since the late 1970s abstract the present paper develops an integral view of the year to year variability across the entire asian australian monsoon a am system which covers one third of the global tropics between 40 and 160 e using season reliant empirical orthogonal function s eof analysis the authors identified two major modes of variability for the period 1956 2004 the first exhibits a prominent biennial tendency and concurs with the turnabout of el nino southern oscillation enso providing a new perspective of the seasonally evolving spatiotemporal structure for tropospheric biennial oscillation the second mode leads enso by one year the remote el nino forcing the monsoon warm pool ocean interaction and the influence of the annual cycle are three fundamental factors for understanding the behavior of the first mode the monsoon ocean interaction is characterized by a positive feedback between the off equatorial convectively coupled rossby waves and the underlying sea surface temperature sst dipole anoma

intraseasonal convection and air sea fluxes over the indian monsoon region revealed from the bimodal iso index the present study aims to elucidate the intraseasonal oscillations iso of atmospheric convection and air sea fluxes over the indian region during summer monsoon season to accomplish this the study employs the extended empirical orthogonal function based bimodal iso index developed by kikuchi et al clim dyn 38 9 10 1989 2000 2012 the propagation of deep convective anomalies and air sea fluxes are explored during the different phases p1 p8 of the bimodal index this is achieved by examining the tropical rainfall measuring mission satellite rainfall outgoing long wave radiation olr sea surface temperatures sst downward shortwave radiation dsr and reanalysis products of 850 hpa winds potential vorticity and latent heat fluxes lhfs composite analysis of the anomalies depicts the strong weak northward eastward propagation of convective anomalies over the indian region equatorial indian ocean over the indian region active suppressed or weak convection is evident during the phases of p4 and p5 p1 p2 and p7 p8 enhanced deep convection is lead by a phase of 850 hpa westerly winds and negative sst anomalies signatures of iso during different phases are examined from research moored array for african asian australian monson analysis and prediction rama buoy observations over the bay of bengal rainfall sst and lhf anomalies from rama buoy measurements are in concurrence with the spatial composites of bimodal iso phases plausible drivers for the variability of intraseasonal convection and air sea fluxes were reviewed using published observational and modelling studies findings from the present study advocate the applicability of kikuchi bimodal index clim dyn 38 9 10 1989 2000 2012 over the indian region and have practical application for the validation of ocean atmospheric coupled models

el nino related summer precipitation anomalies in southeast asia modulated by the atlantic multidecadal oscillation abstracthow the atlantic multidecadal oscillation amo affects el nino related signals in southeast asia is investigated in this study on a subseasonal scale based on observational and reanalysis

pan arctic patterns in black carbon sources and fluvial discharges deduced from radiocarbon and pah source apportionment markers in estuarine surface sediments 1 a pan arctic geospatial picture of black carbon bc characteristics was obtained from the seven largest arctic rivers by combining with molecular combustion markers polycyclic aromatic hydrocarbons and radiocarbon 14c analysis the results suggested that the contribution from modern biomass burning to bc ranged from low in the yukon 8 and lena 5 rivers to high in the yenisey river 88 the mackenzie river contributed almost half of the total arctic fluvial bc export of 202 kton a 1 kton 109 g with the five russian arctic rivers contributing 10 36 kton a 1 each the 14c based source estimate of fluvially exported bc to the arctic ocean weighted by the riverine bc fluxes amount to about 20 from vegetation biofuel burning and 80 from 14c extinct sources such as fossil fuel combustion and relict bc in uplifted source rocks combining these pan arctic data with available estimates of bc export from other rivers gave a revised estimate of global riverine bc export flux of 26 103 kton a 1 this is twice higher than a single previous estimate and confirms that river export of bc is a more important pathway of bc to the oceans than direct atmospheric deposition

onset of asian desertification by 22 myr ago inferred from loess deposits in china the initial desertification in the asian interior is thought to be one of the most prominent climate changes in the northern hemisphere during the cenozoic era1 2 3 4 but the dating of this transition is uncertain partly because desert sediments are usually scattered discontinuous and difficult to date here we report nearly continuous aeolian deposits covering the interval from 22 to 6 2 million years ago on the basis of palaeomagnetic measurements and fossil evidence a total of 231 visually definable aeolian layers occur as brownish loesses interbedded with reddish soils this new evidence indicates that large source areas of aeolian dust and energetic winter monsoon winds to transport the material must have existed in the interior of asia by the early miocene epoch at least 14 million years earlier than previously thought3 5 regional tectonic changes and ongoing global cooling are probable causes of these changes in aridity and circulation in asia

nanofiber calcite in asian dust and its atmospheric roles 1 calcite is the most important mineral in asian dust and it reacts with atmospheric gases during its long range transport mineralogical and chemical analyses of asian dust and source soils showed two types of calcite that differ greatly in morphology and origin i micron sized irregular particles derived from the erosion of bedrock and ii nanosized fibers that were chemically precipitated in soils in asian dust aerosol particles these nanofibers were internally mixed with clay minerals often coating quartz and feldspar grains together with clay minerals nanofiber bearing aerosol particles were more abundant than the coarser calcite particles the nanofibers reacted to form sulfate coatings on minerals providing a significant contribution to the optical chemical and hygroscopic modifications of asian dust due to their enhanced reactivity asian dust is basically a mineral aerosol and its mineralogical diversity needs to be characterized before a proper estimation of its climatic geochemical and ecological roles and provenance

a model for the boreal summer intraseasonal oscillation abstract the tropical intraseasonal oscillation iso exhibits pronounced seasonality the boreal summer iso is more complex than its winter counterpart due to the coexistence of equatorial eastward off equatorial westward and northward propagating low frequency modes and their interactions based on observational evidence and results obtained from numerical experiments a mechanism is proposed for the boreal summer iso in which the northern hemisphere summer monsoon nhsm circulation and moist static energy distribution play essential roles with a climatological july mean basic state the life cycle of model low frequency waves consists of four processes an equatorial eastward propagation of a coupled kelvin rossby wave packet an emanation of moist rossby waves in the western pacific a westward propagation and amplification of the rossby waves in south asian monsoon regions and a reinitiation of the equatorial disturbances over the central indian ocean the life cycle spans about one month and p

coastal erosion vs riverine sediment discharge in the arctic shelf seas this article presents a comparison of sediment input by rivers and by coastal erosion into both the laptev sea and the canadian beaufort sea cbs new data on coastal erosion in the laptev sea which are based on field measurements and remote sensing information and existing data on coastal erosion in the cbs as well as riverine sediment discharge into both the laptev sea and the cbs are included strong regional differences in the percentages of coastal erosion and riverine sediment supply are observed the cbs is dominated by the riverine sediment discharge 64 45 106 t a 1 mainly of the mackenzie river which is the largest single source of sediments in the arctic riverine sediment discharge into the laptev sea amounts to 24 10 106 t a 1 more than 70 of which are related to the lena river in comparison with the cbs the laptev sea coast on average delivers approximately twice as much sediment mass per kilometer a result of higher erosion rates due to higher cliffs and seasonal ice melting in the laptev sea sediment input by coastal erosion 58 4 106 t a 1 is therefore more important than in the cbs and the ratio between riverine and coastal sediment input amounts to 0 4 coastal erosion supplying 5 6 106 t a 1 is less significant for the sediment budget of the cbs where riverine sediment discharge exceeds coastal sediment input by a factor of ca 10

the enso asian monsoon interaction in a coupled ocean atmosphere gcm abstract in this study the authors evaluate the el nino southern oscillation enso asian monsoon interaction in a version of the hadley centre coupled ocean atmosphere general circulation model cgcm known as hadcm3 the main focus is on two evolving anomalous anticyclones one located over the south indian ocean sio and the other over the western north pacific wnp these two anomalous anticyclones are closely related to the developing and decaying phases of the enso and play a crucial role in linking the asian monsoon to enso it is found that the hadcm3 can well simulate the main features of the evolution of both anomalous anticyclones and the related sst dipoles in association with the different phases of the enso cycle by using the simulated results the authors examine the relationship between the wnp sio anomalous anticyclones and the enso cycle in particular the biennial component of the relationship it is found that a strong el nino event tends to be followed by a more rapid decay and i