the medieval climate anomaly in the iberian peninsula reconstructed from marine and lake records abstract selected multi proxy and accurately dated marine and terrestrial records covering the past 2000 years in the iberian peninsula ip facilitated a comprehensive regional paleoclimate reconstruction for the medieval climate anomaly mca 900 1300 ad the sequences enabled an integrated approach to land sea comparisons and despite local differences and some minor chronological inconsistencies presented clear evidence that the mca was a dry period in the mediterranean ip it was a period characterized by decreased lake levels more xerophytic and heliophytic vegetation a low frequency of floods major saharan eolian fluxes and less fluvial input to marine basins in contrast reconstruction based on sequences from the atlantic ocean side of the peninsula indicated increased humidity the data highlight the unique characteristics of the mca relative to earlier the dark ages da ca 500 900 years ad and subsequent the little ice age lia 1300 1850 years ad colder periods the reconstruction supports the hypothesis of trouet et al 2009 that a persistent positive mode of the north atlantic oscillation nao dominated the mca

dinoflagellate cyst assemblages as tracers of sea surface conditions in the northern north atlantic arctic and sub arctic seas the new n 677 data base and its application for quantitative palaeoceanographic reconstruction the distribution of dinoflagellate cyst dinocyst assemblages in surface sediment samples from 677 sites of the northern north atlantic arctic and sub arctic seas is discussed with emphasis on the relationships with sea surface parameters including sea ice cover salinity and temperature of the coldest and warmest months difficulties in developing a circum arctic data base include the morphological variation within taxa e g operculodinium centrocarpum islandinium cezare and polykrikos sp which probably relate to phenotypic adaptations to cold and or low salinity environments sparse hydrographical data together with large interannual variations of temperature and salinity in surface waters of arctic seas constitute additional limitations nevertheless the use of the best analogue technique with this new dinocyst data base including 677 samples permits quantitative reconstruction of sea surface conditions at the scale of the northern north atlantic and the arctic domain the error of prediction calculated from modern assemblages is 1 3 ca nd 1 8 c for the temperature of february and august respectively 1 8 for the salinity and 1 5 months yr 1 for the sea ice cover application to late quaternary sequences from the western and eastern subpolar north atlantic labrador sea and barents sea provide reconstructions compatible with those obtained using the previous dinocyst data base n 371 which mainly included modern data from the northern north atlantic copyright 2001 john wiley sons ltd journal of quaternary science

climatology of strong intermountain cold fronts abstract motivated by the intensity and severity of winds and temperature falls that frequently accompany rapidly developing cold fronts in northern utah this paper presents a 25 yr climatology of strong cold frontal passages over the intermountain west and adjoining western united states using conventional surface observations and the north american regional reanalysis strong cold frontal passages are identified based on a temperature fall of 7 c or greater in a 2 3 h period a concurrent pressure rise of 3 hpa or greater and the presence of a large scale 700 hpa temperature gradient of at least 6 c 500 km 1 the number of strong cold frontal passages exhibits a strong continental signature with very few events 10 along the pacific coast and more than 200 events east of the continental divide the number of events increases dramatically from the cascade mountains and sierra nevada to northern utah indicating that the intermountain west is a frequent cold front breeding ground a composite of th

causes of variability in light absorption by particles in snow at sites in idaho and utah this file accompanies namer2014snowbc dohertyetal v1 xlsx which contains data on black carbon bc and other light absorbing particles in snow in utah and idaho for samples collected january march 2014 in jan feb 2013 and 2014 in utah data are available as an excel file with headers or as a comma separated data file with no headers there is one entry per layer of snow sampled all entries other than column titles in the xlsx are numeric detailed information on our measurements can be found in a series of publications as given below description of the instrument and method used to make the measurements grenfell t c s j doherty a d clarke and s g warren spectrophotometric determination of absorptive impurities in snow appl opt 50 14 pp 2037 2048 2011 summary and discussion of dataset namer2014snowbc dohertyetal xlsx including maps of sample locations doherty s j d a hegg p k quinn j e johnson j p schwarz c dang and s g warren causes of variability in light absorption by particles in snow at sites in idaho and utah j geophys res atmos 121 doi 10 1002 2015jd024375 2016 note that the measurement and analysis techniques used to produce these data were also used in a broad arctic survey 2006 2010 of bc and other light absorbing particles snow as reported here doherty s j s g warren t c grenfell a d clarke and r e brandt light absorbing impurities in arctic snow atmos chem phys 10 11647 11680 doi 10 5194 acp 10 11647 2010 2010 http www atmos chem phys net 10 11647 2010 acp 10 11647 2010 html

the phytoplankton bloom in the northwestern arabian sea during the southwest monsoon of 1979 the biological variability of the northwestern arabian sea during the 1979 southwest monsoon has been investigated by the synthesis of satellite ocean color remote sensing with analysis of in situ hydrographic and meteorological data sets and the results of wind driven modeling of upper ocean circulation the phytoplankton bloom in the northwestern arabian sea peaked during august september extended from the oman coast to about 65 e and lagged the development of open sea upwelling by at least 1 month in total the pigment distributions hydrographic data and model results all suggest that the bloom was driven by spatially distinct upward nutrient fluxes to the euphotic zone forced by the physical processes of coastal upwelling and offshore ekman pumping coastal upwelling was evident from may through september yielded the most extreme concentrations of phytoplankton biomass and along the arabian coast was limited to the continental shelf in the promotion of high concentrations of phytoplankton upward ekman pumping to the northwest of the somali jet axis stimulated the development of a broad open sea phytoplankton bloom oceanward of the oman shelf vertical mixing during the 1979 southwest monsoon was apparently not a primary cause of the regional scale phytoplankton bloom

onset of the somali jet in the arabian sea during june 1997 the national aeronautics and space administration scatterometer surface wind vectors are used to describe the rapid onset of the somali jet throughout the arabian sea in june 1997 the time of somali jet onset varied over the arabian sea with june 17 18 the average time the somali jet appeared first in the western arabian sea expanded over 2 weeks to encompass the arabian sea and produced a threefold increase in surface wind convergence in the eastern arabian sea the onset time of the 12 m s 1 isotach preceded by 3 4 days the onset of monsoon rainfall in goa for somali jet wind speeds above 10 m s 1 the 2 day 1 1 sea surface temperature decreased 0 5 c per 1 m s 1 increase in collocated wind speed the somali jet created a north south distribution of ekman pumping and suction in the central arabian sea to enhance the eastward surface current by 0 1 m s 1 the somali jet doubled the southward ekman transport across the southern boundary of the arabian sea in june 1997 when the most intense el nino episode of the century was in its onset phase the southward ekman transport across the southern boundary of the arabian sea was one half that observed since 1992

late little ice age palaeoenvironmental records from the anzali and amirkola lagoons south caspian sea vegetation and sea level changes abstract two internationally important ramsar lagoons on the south coast of the caspian sea cs have been studied by palynology on short sediment cores for palaeoenvironmental and palaeoclimatic investigations the sites lie within a small area of very high precipitation in a region that is otherwise dry vegetation surveys and geomorphological investigations have been used to provide a background to a multidisciplinary interpretation of the two sequences covering the last four centuries in the small lagoon of amirkola the dense alder forested wetland has been briefly disturbed by fire followed by the expansion of rice paddies from ad1720 to 1800 on the contrary the terrestrial vegetation reflecting the diversity of the hyrcanian vegetation around the lagoon of anzali remained fairly complacent over time the dinocyst and non pollen palynomorph assemblages revealing changes that have occurred in water salinity and water levels indicate a high stand during the late little ice age lia from ad

atlas of modern dinoflagellate cyst distributions in the black sea corridor from aegean to aral seas including marmara black azov and caspian seas abstract we present the first comprehensive taxonomic and environmental study of dinoflagellate cysts in 185 surface sediment samples from the black sea corridor bsc which is a series of marine basins extending from the aegean to the aral seas including marmara black azov and caspian seas for decades these low salinity semi enclosed or endorheic basins have experienced large scale changes because of intensive agriculture and industrialisation with consequent eutrophication and increased algal blooms the bsc atlas data provide a baseline for improved understanding of linkages between surface water conditions and dinoflagellate cyst dinocyst distribution diversity and morphological variations by cross reference to dinocyst occurrences in sediment cores with radiocarbon ages covering the past c 11 700 years the history of recent biodiversity changes can be evaluated the seabed cyst samples integrate seasonal and multi year data which are not usually captured by plankton samples and the cyst composition can point to presence of previously unrecorded motile dinoflagellate species in the bsc results show the presence of at least 71 dinocyst taxa of which 36 can be related to motile stages recorded in the plankton comparison with sediment core records shows that five new taxa appear to have entered or re entered the region over the past century statistical analysis of the atlas data reveals the presence of four ecological assemblages which are primarily correlated with seasonal and annual surface water salinity and temperature correlation with phosphate nitrate and silicate nutrients chlorophyll a and bottom water oxygen is less clear but may be important for some taxa biodiversity indices reveal strong west east biogeographical differences among the basins that reflect the different histories of mediterranean versus ponto caspian connections the atlas data provide a standardised taxonomy and regional database for interpreting downcore cyst variations in terms of quantitative oceanographic changes the atlas also provides a baseline for monitoring further changes in the bsc dinocysts that may accompany the accelerating development of the region

quaternary evolution of the ria de vigo spain abstract the seismic analysis of the sedimentary infill of the ria de vigo reveals that the infill comprises of a fifth order sequence 18 ky bounded by a major discontinuity surface within the holocene sequence several seismic units have been identified the oldest one originated after the wurm glaciation and the origin of its top discontinuity was eroded during the regression sea level at 120 m of this last glacial episode isotopic stages 2 to 4 18 ky b p in some places below this ria infill another sequence can be identified this older sequence is associated with the pre existing faults and troughs in the deepest parts of the ria and it was deposited during the wurm glaciation miocene pleistocene eroded sediments were moved from the rias area to deeper zones where they accumulated in the lowstand system tract the next sea level rise occured in two steps producing two transgressive units separated by an hiatus surface this cycle was interrupted by the next sea level fall to 55 m marked on the seismic records by another recognizable boundary the next sea level rise took place in several steps back stepping with some stillstands generating another transgressive system tract in the ria from that time on the relative sea level continued rising depositing the most recent unit which represents the highstand system tract separating the highstand system tract and the transgresive unit below there is a consensed section the analysis of 29 cores provides groundtruthing for our hypothesis the identified main lithologic units show a transgressive sequence a granitic rock base an overlying second unit locally wedge shaped and most recently a marine muddy unit covering the present ria seafloor

surface waters of the nw iberian margin upwelling on the shelf versus outwelling of upwelled waters from the rias baixas abstract a set of hydrographic surveys were carried out in the ria of vigo nw spain at 2 4 d intervals during four 2 3 week periods in 1997 covering contrasting seasons residual exchange fluxes with the adjacent shelf were estimated with a 2 d non steady state salinity temperature weighted box model exchange fluxes consist of a steady state term dependent on the variability of continental runoff and a non steady state term dependent on the time changes of density gradients in the embayment more than 95 of the short time scale variability of the exchange fluxes in the middle and outer ria can be explained by the non steady state term that in turns is correlated r 2 75 with the offshore ekman transport conversely 96 of the variability of exchange fluxes in the inner ria rely on the steady state term the outer and middle ria are under the direct influence of coastal upwelling which enhances the positive residual circulation pattern by an order of magnitude from 10 2 to 10 3 m 3 s 1 on the contrary downwelling provokes a reversal of the circulation in the outer ria the position of the downwelling front along the embayment depends on the relative importance of ekman transport q x m 3 s 1 km 1 and continental runoff r m 3 s 1 when q x r 7 2 the reversal of the circulation affects the middle ria our results are representative for the rias baixas four large coastal indentations in nw spain during the upwelling season spring and summer 60 of shelf surface waters off the rias baixas consist of fresh eastern north atlantic central water enacw upwelled in situ the remaining 40 consists of upwelled enacw that previously enters the rias and it is subsequently outwelled after thermohaline modification during the downwelling season autumn and winter 40 of the warm and salty oceanic subtropic surface water which piled on the shelf by the predominant southerly winds enters the rias

ocean atmosphere covariability in the western arabian sea abstract the western arabian sea exhibits strong spatial variability in sea surface temperature sst during the southwest monsoon with changes in sst that can exceed 5 c over 200 km exploration of satellite based and in situ data shows a strong connection between mesoscale sst features and changes in the atmospheric boundary layer the fundamental relationship is that of weak strong wind velocities overlying cold warm sst features there are also coherent changes in other near surface meteorological parameters such as the air sea temperature difference and relative humidity indicating changes in the stability of the planetary boundary layer over the mesoscale sst features these relationships are similar to those recently reported over the equatorial pacific tropical instability wave region this observed covariability of atmospheric boundary layer structure and sst results in variations of the surface heat and moisture fluxes latent heat flux is modified by changes in relative humidity principa

characterisation and preliminary quantification of the methane reservoir in a coastal sedimentary source san simon bay ria de vigo nw spain abstract ria de vigo is a river valley flooded by the sea with a bay san simon bay at its innermost part the accumulation of holocene sediment in san simon bay has been studied by the integration of 1 large scale high resolution seismic data and 2 detailed geochemical analysis of a gravity core in san simon bay the majority of the seismic records are obscured by acoustic turbidity which represents gassy sediments but on records from rande strait it is possible to distinguish two quaternary seismic sequences an upper pleistocene sequence sq1 and a holocene sequence sq2 only sq2 is recognized in san simon bay where it is comprised of two seismic units the upper unit represents the hst sediment i e the period of highest sea level a gravity core taken within the gassy zone at 10 m water depth provided 3 55 m of fine grained sediments muds from the youngest seismic unit 4 m thick geochemical analysis show high values 4 to 10 of toc sediment and porewater analyses indicate a distinct sulphate methane transition zone smtz between 60 and 80 cm where sulphate is depleted to 0 4 mm the top of the acoustic turbidity the gas front at 80 cm corresponds to the lower limit of the smtz the methane cannot have been derived from the underlying metamorphic and granitic rocks but was probably derived by microbial degradation of the organic matter in the holocene sediments we estimate that the sediments of the bay contain approximately 1 8 10 6 m 3 of organic carbon and 275 ton of methane

persistent positive north atlantic oscillation mode dominated the medieval climate anomaly the medieval climate anomaly mca was the most recent pre industrial era warm interval of european climate yet its driving mechanisms remain uncertain we present here a 947 year long multidecadal north atlantic oscillation nao reconstruction and find a persistent positive nao during the mca supplementary reconstructions based on climate model results and proxy data indicate a clear shift to weaker nao conditions into the little ice age lia globally distributed proxy data suggest that this nao shift is one aspect of a global mca lia climate transition that probably was coupled to prevailing la nina like conditions amplified by an intensified atlantic meridional overturning circulation during the mca

a two step expansion of the dinocyst lingulodinium machaerophorum in the caspian sea the role of changing environment dinoflagellate cyst assemblages were analysed in four short sediment cores collected in the south basin of the caspian sea for assessing environmental changes over the last few millennia two of these cores were dated by radionuclides the sedimentation rate of one of them was very high in the order of 20 mm per year the interpretation of the four sequences is supported by a collection of 27 lagoonal or marine surface sediment samples a sharp increase in the concentration of the dinocyst occurs after 1967 especially owing to lingulodinium machaerophorum considering nine other cores covering parts or the whole of holocene it became clear that this species started to develop in the caspian sea only during the last three millennia by analysing instrumental data and collating existing reconstructions of sea level changes over the last decades we show that the main forcing for the recent increase of l machaerophorum percentages and concentration is global climate change especially sea surface temperature increase sea level fluctuations likely only have a minor impact we argue that the recent increase in l machaerophorum indicates that the caspian sea clearly is in the anthropocene

climate and anthropogenic factors influencing an estuarine ecosystem from nw iberia new high resolution multiproxy analyses from san simon bay ria de vigo abstract two sedimentary sequences coastal and subtidal were studied in san simon bay ria de vigo situated on the atlantic coast of nw iberia the coastal record is a shallowing upward sequence which evidences a locally developed low marsh situated below the current beach and dated at the second half of the 4th century during the following decades this low marsh was progressively replaced by an alder swamp which formed on it this suggests an apparent stabilisation or slow down of the relative sea level rsl in this site at the beginning of the dark ages da the subtidal sequence studied reflects the main changes in the landscape the hydrological conditions climate and rsl affecting this part of nw iberia during the last 1250 years evidence of changing dinocysts content in the sediment reveals that two centennial or decadal scale episodes existed of shelf marine waters more intensely penetrating inside the bay between the 15th 18th centuries and at ca 1800 1930 ad besides we related different proxies with the occurrence of four main climatic stages namely the previously described dark ages da ca 350 750 ad the mediaeval climatic anomaly mca ca 750 1100 ad and the little ice age lia ca 1500 1930 ad in addition we propose a regional mca lia transition ca 1100 1500 ad that it has not been previously described our environmental characterization indicates a persistent north atlantic oscillation nao negative mode domain in ria de vigo during the mca but this became weaker during the lia and probably also during the earlier da nao mode become more irregular during the mca lia transition generally persisting in dominant negative mode except for a phase of minor upwelling intensification at ca 1150 1350 ad which mainly affected the external parts of the ria we postulate that an almost simultaneous phase ca 1100 1350 ad of stronger continental contribution in the sediments may be related to increasing storm intensities probably linked to a reinforcement of the easter atlantic ea pattern and also that the intertidal supratidal ecosystems inside san simon bay may have extended further in the past at least towards the end of the 5th century and between ca 1050 1350 ad and ca 1450 1750 ad a number of local historical references are consistent with our palaeoecological data and so support the chronology proposed as well as many of the environmental changes reconstructed this good agreement will help in the interpretation of other analogous sequences extending back in time

last interglacial eemian hydrographic conditions in the southwestern baltic sea based on dinoflagellate cysts from ristinge klint denmark a dinoflagellate cyst record with strong mediterranean lusitanian affinities is described from marine deposits of eemian age last interglacial late pleistocene at ristinge klint denmark revealing new information about the hydrographic evolution of the southwestern baltic sea a revised correlation of the pollen record at ristinge klint with that of the annually laminated site at bispingen in northern germany provides temporal control approximately the first quarter of eemian time is represented a marine ingression into a lake took place during the quercus rise about 300years into the interglacial and is marked by low c 3 psu salinities at the base of the cyprina clay that increased progressively an abrupt and significant rise in the inflow of warm saline waters from the north sea occurred at about 750 years into the interglacial the corylus rise and at about 1900 years into the interglacial strongly stratified waters developed higher in the cyprina clay and continuing to its top at nearly 3000 years into the interglacial more open marine waters are indicated although fully marine conditions were not reached the dinoflagellate record throughout the cyprina clay at ristinge klint is therefore one of increasing marine influence summer sea surface temperatures approached and may have exceeded 26 28 c during early eemian time indicating temperatures at least 5 c warmer than at present these warm conditions persisted to the top of the record at ristinge klint no evidence exists at ristinge klint for the influence of arctic watermasses and the paucity of cold water species throughout the section reflects mild winter temperatures in the southwestern baltic sea the new species spiniferites ristingensis is formally described and the name operculodinium centrocarpum var cezare de vernal goyette rodrigues 1989 is validated

albedo of dirty snow during conditions of melt the evolution of spectrally averaged albedo wavelengths between 0 28 m and 2 8 m of snow surfaces treated with known initial concentrations of particles of submicron sized soot and air fall volcanic ash was investigated during conditions of natural melt depending on the particle type and concentration the initial applications reduced the surface albedo to values ranging from 0 18 to 0 41 which were substantially lower than the albedo of the untreated natural snow about 0 61 many of the soot particles flushed through the snowpack with the meltwater and surface concentrations of soot greater than about 5 10 7 kg kg did not persist for more than a few days the migration of particles to depth caused the snow to brighten after the initial application thus limiting the amount of albedo reduction and the consequent effects on melting nevertheless the soot remaining near the surface had a substantial long term effect the residual concentration of 5 10 7 kg kg persisted for several weeks and compared to the untreated surface reduced the albedo by about 30 and increased melting by 50 particles of volcanic ash with diameters larger than about 5 m remained at or near the snow surface although many of the smaller particles flushed through the snow with the meltwater the surface albedo was not changed significantly by their removal the different behaviors of the ash and soot are probably related to the difference in their particle size distributions in relation to the thickness of water films that form the transport paths under conditions of partial saturation that are characteristic of melting snow

contrasting sea surface responses between the western mediterranean sea and eastern subtropical latitudes of the north atlantic during abrupt climatic events of mis 3 abstract dinoflagellate cyst dinocyst analysis was conducted on two cores from the sw iberian margin and central alboran sea from which high quality records of marine isotope stage 3 have been previously derived our aim in this study is to compare the dinocyst signature between 50 and 25 ka bp with existing datasets of foraminiferal and geochemical proxies related to hydrological parameters quantitative reconstructions of sea surface temperatures ssts and salinities sss based on dinocysts are performed for the first time in this area the results are compared to ssts derived from planktonic foraminifera and alkenone measurements and to sss calculated from planktonic 18 o and foraminiferal sst significant oscillations related to dansgaard oeschger cycles are recorded in both cores dinocyst derived hydrological parameters exhibit synchronous fluctuations and similar values to those derived from the other methods in particular when considering quantitative reconstructions for february based on foraminifera and dinocysts our study shows that the influence of subpolar waters was felt during each greenland stadial gs off portugal and that the amplification of the heinrich stadial cooling in the alboran sea was related to the penetration of subpolar waters through the strait of gibraltar during greenland interstadials gi we provide evidence for the occurrence of warm and nutrient rich sea surface waters in the alboran sea probably due to gyre induced upwelling finally the difference between august and february dinocyst sst estimates suggests higher seasonal contrasts during gs compared to gi at the two core sites additionally precession appears to have an imprint on dinocyst derived long term seasonality record however this observation needs to be confirmed by longer records

distribution of dinoflagellate cysts in surface sediments of the northern north atlantic in relation to nutrient content and productivity in surface waters abstract analyses of dinoflagellate cyst assemblages from the surface sediments of 371 sites from the north atlantic ocean were performed in order to define relationships with nitrate phosphate silica and productivity in the upper water layer statistical analyses reveal close links between dinocyst assemblages and nitrate content in february that provide a measurement of nitrate availability amongst the taxa in the assemblages nematosphaeropsis labyrinthus which positively correlates with nutrients shows an eutrophic relationship whereas impagidinium aculeatum impagidinium patulum spiniferites ramosus spiniferites mirabilis and lingulodinium machaerophorum have a rather oligotrophic relationship on these grounds transfer functions were tested using multiple regressions and the best analogue technique to reconstruct nitrate content both methods yielded reasonable estimates and allow the reconstruction of the nitrate concentrations in february with an accuracy better than 1 45 mol m 3 at the scale of the study area there are also tenuous links between the dinocyst assemblages and productivity transfer functions were tentatively tested for the reconstruction of annual productivity and yield estimates with an accuracy of about 26 5 gc m 2 year 1 these results demonstrate that dinocyst assemblages can be used for the reconstruction of productivity and nitrates

air sea interaction over the upwelling region of the somali coast 1 during the southwest monsoon two upwelling cells are established along the somali coast around 4 n 5 n and 10 n the sea surface temperatures ssts over these regions can fall to about 22 c on average during this time using satellite derived data the covariability in wind and sst is examined for the months of june august 2005 a particularly strong upwelling season in july 2005 when a strong localized upwelling event occurred near 4 n 5 n the somali jet which establishes itself along the coast during june august was found to have oscillated at a frequency of about 4 8 weeks high covariability in mesoscale winds and ssts were found over the upwelling region the observed covariability of wind and ssts is argued to be the result of sst modulation of the atmospheric stability such that over warm temperatures the unstable atmosphere brings down high winds and over cold temperatures the stable atmosphere decelerates the surface winds these sst induced changes in the lower atmosphere lead to changes in wind stress divergence and a dipole in wind stress curl across the cold filament with negative positive curl upstream downstream of the cold tongue

oceanic pollen transport and pollen dinocyst ratios as markers of late cenozoic sea level change and sediment transport abstract palynological studies of late cenozoic cores from nine sites show large peaks in the ratio of pollen and spores to dinocysts p d which reflect major increases in terrigenous sediment influx to the north atlantic ocean under normal pelagic conditions in the north atlantic i e in the absence of ice rafting or mass wasting p d in oceanic sediments is low usually

regional variability in dust on snow processes and impacts in the upper colorado river basin dust deposition onto mountain snow cover in the upper colorado river basin frequently occurs in the spring when wind speeds and dust emission peaks on the nearby colorado plateau dust loading has increased since the intensive settlement in the western usa in the mid 1880s the effects of dust on snow have been well studied at senator beck basin study area sbbsa in the san juan mountains co the first high altitude area of contact for predominantly southwesterly winds transporting dust from the southern colorado plateau to capture variability in dust transport from the broader colorado plateau and dust deposition across a larger area of the colorado river water sources an additional study plot was established in 2009 on grand mesa 150 km to the north of sbbsa in west central co here we compare the 4 year 2010 2013 dust source deposition and radiative forcing records at grand mesa study plot gmsp and swamp angel study plot sasp sbbsa s subalpine study plot the study plots have similar site elevations environments and differ mainly in the amount of dust deposited and ensuing impacts at sasp end of year dust concentrations ranged from 0 83 mg g 1 to 4 80 mg g 1 and daily mean spring dust radiative forcing ranged from 50 65 w m 2 advancing melt by 24 49 days at gmsp which received 1 0 mg g 1 less dust per season on average spring radiative forcings of 32 50 w m 2 advanced melt by 15 30 days remote sensing imagery showed that observed dust events were frequently associated with dust emission from the southern colorado plateau dust from these sources generally passed south of gmsp and back trajectory footprints modelled for observed dust events were commonly more westerly and northerly for gmsp relative to sasp these factors suggest that although the southern colorado plateau contains important dust sources dust contributions from other dust sources contribute to dust loading in this region and likely account for the majority of dust loading at gmsp copyright 2015 john wiley sons ltd

aeolian dust in colorado plateau soils nutrient inputs and recent change in source aeolian dust windblown silt and clay is an important component in arid land ecosystems because it may contribute to soil formation and furnish essential nutrients few geologic surfaces however have been characterized with respect to dust accumulation history and resultant nutrient enrichment we have developed a combination of methods to identify the presence of aeolian dust in arid regions and to evaluate the roles of this dust in ecosystem processes unconsolidated sandy sediment on isolated surfaces in the canyonlands region of the colorado plateau differs greatly in mineralogical and chemical composition from associated bedrock mainly aeolian sandstone detrital magnetite in the surficial deposits produces moderately high values of magnetic susceptibility but magnetite is absent in nearby bedrock a component of the surficial deposits must be aeolian to account for the abundance of magnetite which formed originally in far distant igneous rocks particle size analysis suggests that the aeolian dust component is typically as much as 20 30 dust inputs have enriched the sediments in many elements including p mg na k and mo as well as ca at sites where bedrock lacks calcite cement soil surface biologic crusts are effective dust traps that apparently record a change in dust sources over the past several decades some of the recently fallen dust may result from human disturbance of land surfaces that are far from the canyonlands such as the mojave desert some land use practices in the study area have the potential to deplete soil fertility by means of wind erosion removal of aeolian silt

intraseasonal variability of the low level jet stream of the asian summer monsoon abstract the strong cross equatorial low level jet stream llj with its core around 850 hpa of the asian summer monsoon june september is found to have large intraseasonal variability during the monsoon onset over kerala india and during break monsoon periods when the convective heating of the atmosphere is over the low latitudes of the indian ocean the axis of the llj is oriented southeastward over the eastern arabian sea and it flows east between sri lanka and the equator and there is no llj through peninsular india this affects the transport of moisture produced over the indian ocean to peninsular india and the bay of bengal in contrast during active monsoon periods when there is an east west band of strong convective heating in the latitudes 10 20 n from about longitude 70 to about 120 e the llj axis passes from the central arabian sea eastward through peninsular india and it provides moisture for the increased convection in the bay of bengal and for the monsoon depressions forming there

surface sediment dinoflagellate cysts from the hudson bay system and their relation to freshwater and nutrient cycling abstract surface sediment samples from the hudson bay system were analysed in order to examine the role of key regulators of arctic marine productivity light and nutrients as affected by freshwater stratification and sea ice cover on the spatial distribution and production of dinoflagellate cysts total cyst fluxes vary from 0 2 10 6 to 30 6 10 6 cysts m 2 a 1 with the highest values observed in eastern hudson bay a total of 24 cyst taxa representing 11 genera of five orders were identified and distribution maps of the most common taxa have been produced this is the first record of echinidinium aculeatum echinidinium karaense cf echinidinium delicatum islandinium brevispinosum selenopemphix quanta cysts of protoperidinium americanum cysts of cf biecheleria sp and polarella glacialis in the hudson bay system dinoflagellate cyst assemblages show distinct spatial patterns revealing three compositional domains eastern hudson bay western central hudson bay and hudson strait the eastern domain is characterised by a dominance of autotrophic cysts of pentapharsodinium dalei whereas the western central domain is characterised by autotrophic operculodinium centrocarpum with some contribution by heterotrophic polykrikos sp var arctic morphotype and polykrikos spp sites from hudson strait are distinguished by an overwhelming prevalence of heterotrophic protoperidiniaceae cysts mainly islandinium minutum and have the highest values of sedimentary biogenic silica used as a proxy for diatom productivity sediment geochemical tracers are used as proxies for freshwater inputs lignin and its biomarkers and nitrate availability nitrogen isotopes and sea ice concentrations derived from passive microwave data as a proxy for light availability sea ice regulated length of the dark season has a negligible influence on the proportion and production of heterotrophic dark adapted versus autotrophic light dependent dinoflagellate cysts perhaps due to the location of our study area on the southern fringe of the arctic instead cyst populations in hudson bay are primarily regulated by vertical stratification and nitrate availability while in hudson strait the pivotal mechanism constitutes food availability

contemporary geochemical composition and flux of aeolian dust to the san juan mountains colorado united states 1 dust deposition in the rocky mountains may be an important biogeochemical flux from upwind ecosystems seasonal winter spring dust mass fluxes to the san juan mountains during the period from 2004 to 2008 ranged from 5 to 10 g m 2 with individual deposition events reaching as high as 2 g m 2 dust deposited in the san juan mountains was primarily composed of silt and clay sized particles indicating a regional source area the concentrations of most major and minor elements in this dust were similar to or less than average upper continental crustal concentrations whereas trace element concentrations were often enriched in particular dust collected from the san juan mountain snowpack was characterized by enrichments of heavy metals including as cu cd mo pb and zn the mineral composition of dust partially explained dust geochemistry however based on results of a sequential leaching procedure it appeared that trace element enrichments were associated with the organic and not the mineral fraction of dust our observations show that the dust derived fluxes of several nutrients and trace metals are substantial and because many elements are deposited in a mobile form could be important controls of vegetation soil or surface water chemistry the flux measurements reported here are useful benchmarks for the characterization of ecosystem biogeochemical cycling in the rocky mountains

annual intensification of the somali jet in a quasi equilibrium framework observational composites the annual intensification of the somali jet which accompanies the onset of the indian summer monsoon is rapid compared to the evolution of the seasonal insolation forcing using observationally based data sets the dynamic and thermodynamic changes accompanying the onset of this jet are presented the abrupt component of jet onset is shown to occur over ocean about 1000 km east of the east african highlands and is accompanied by increases in both deep convection and baroclinic flow over the off equatorial arabian sea these abrupt changes are well separated from the core of the cross equatorial jet which is located over land adjacent to the east african highlands the onset of the somali jet and the associated monsoon are then examined in a convective quasi equilibrium framework such a framework is consistent with the mean summer state in that peak free tropospheric temperatures are nearly collocated with peak subcloud layer entropies over the northern bay of bengal and adjacent coastal regions jet onset is accompanied by a large o 100 w m 2 increase in surface enthalpy flux over the arabian sea that is nearly collocated with and linearly related to the concurrent increase in deep tropospheric ascent at the same time the highest subcloud entropies shift inland slightly from the bay of bengal and the region of warmest free tropospheric temperatures expands poleward the consistency of all of these changes with a wind evaporation feedback and several other hypothesized mechanisms of abrupt monsoon onset is discussed copyright c 2009 royal meteorological society

environmental change in the western iberia upwelling ecosystem since the preindustrial period revealed by dinoflagellate cyst records we present the first multi site study of dinoflagellate cyst records spanning ca ad 1860 2000 from the west iberian coast our aim was to reconstruct environmental changes in the western iberia upwelling ecosystem one of the most biologically productive areas in the world and an active fishery region a major shift in cyst assemblages was recorded off the northwestern shelf sector between 1920 and 1950 towards autotrophic dominance and consisted of a multi fold increase in total cyst concentrations and cysts of lingulodinium polyedrum accompanied by an increase in protoceratium reticulatum cysts the observed changes pre date the industrialization of agriculture in portugal and are concomitant with a shift in the north atlantic oscillation nao towards negative indices higher river input and increasing sea surface temperatures the southernmost record with reduced river and human influence showed only minor changes during the 20th century here an increase in protoperidinioid cysts after the

climatic and anthropogenic impacts on the ria de vigo nw iberia over the last two centuries a high resolution dinoflagellate cyst sedimentary record abstract a high resolution dinoflagellate cyst record spanning the period of 1830 2012 ce from ria de vigo atlantic margin of nw iberia is presented changes in concentrations and percentages of dinoflagellate cysts and freshwater algal spores reflect climatic and anthropogenic influences on the ria i e coastal inlet formed by the partial submergence of a river valley statistical analyses pca and clustering were used to identify the main patterns of change in the cyst assemblages the cyst record was compared with reconstructed and measured instrumental environmental data nao temperatures mean sea level etc to support palaeo reconstructions four main phases were identified the first phase 1830 1855 ce of lower relative sea level rsl temperatures and precipitations represents the last stages of the lia little ice age the second phase 1855 1910 ce is interpreted as a transition between the colder lia and the wetter and warmer conditions that prevailed through the 20th century the third phase 1910 1975 ce is characterized by strong river inputs and water stratification in the ria and the fourth phase 1975 2012 ce reflects impacts of anthropogenic warming and pollution the anthropogenic signal consists of increases in heterotrophic cyst proportions and cysts diversity as well as of a marked decline of potentially toxic lingulodinium machaerophorum increasing organic matter content nutrients and industrial wastes have likely caused detrimental impacts on the autotrophic dinoflagellates by increasing turbidity and toxicity the b5 cyst record and its comparison with previously published data suggest that increased concentrations of l machaerophorum in the 20th century were mainly related to river flow variations that in turn were primarily driven by nao changes rather than cultural eutrophication we also report high abundances of peridinium ponticum in our record determining that this species is not exclusive to the black and marmara seas and has much wider natural distribution

ecmwf and ers 1 surface winds over the arabian sea during july 1995 abstract the european centre for medium range weather forecasts ecmwf and institut francais pour la recherche et l exploitation de la mer european remote sensing satellite named ifr2 surface wind velocity data products are compared during july 1995 over the arabian sea substantial differences were found the central positions of the maximum isotach were separated by 450 km and the ecmwf maximum isotach was 2 m s 1 higher than that of ifr2 ifr2 wind components contained about 10 times more variance than ecmwf winds for horizontal distances from 50 to 250 km along the 8 5 n southern boundary of the arabian sea ecmwf southward ekman transport was higher than that of ifr2 by an amount that could be observed with current measurements the ecmwf and ifr2 difference in upward transport of water into the ekman layer computed from wind stress curl was large enough to measure

high resolution palynological record of holocene climatic and oceanographic changes in the northern south china sea abstract for the first time palynological records of terrestrial palynomorphs and dinoflagellate cysts are investigated in a sediment core from the northern south china sea scs covering the last 12 500 years both terrestrial and marine palynomorph records show strong signals of the sea level change during the studied interval the highest herb pollen content was associated with extensive grasslands on the exposed shelf at the low sea level stand during the younger dryas and early holocene the increase in fern spores and decrease in concentrations of dinoflagellate cysts and terrestrial palynomorphs was observed during the sea level rise interval from 12 500 to 6800 or 6000 cal yr bp then the sea level became stabilized and consistently low dinoflagellate cyst abundances and high abundances of fern spores were recorded a high abundance of impagidinium in the period 12 000 10 400 cal yr bp possibly resulted from increased input of western philippine sea waters into the scs and the branching of the kuroshio current a short term decrease of impagidinium at 11 700 11 000 cal yr bp corresponding to the mwp 1b event might be associated with input of the east china sea waters through the taiwan strait the relationship between the sedimentation rates and the concentrations of terrestrial palynomorphs indicates a water dominant transport for pollen and spore dispersal prior to 6300 cal yr bp whereas wind transport became more prominent thereafter the timing of this change corresponds to the highest sea level stand at 6800 6000 cal yr bp when the present oceanographic setting was formed the mid holocene optimum can be seen by the highest abundance of subtropical tropical broad leaved arboreal pollen and by the highest abundances of dapsilidinium pastielsii three strengthened winter monsoon intervals at 5500 cal yr bp 4000 cal yr bp and 2500 cal yr bp are reflected by increases in pinus pollen content after the present oceanographic condition formed

millennial surface water dynamics in the ria de vigo during the last 3000 years as revealed by coccoliths and molecular biomarkers a combined study of coccolith assemblages and biomarkers in a gravity core collected from the ria de vigo nw spain allowed us to reconstruct the paleoenvironmental conditions for the last 3000 years the quantitative distribution of coccolithophore species points to three different intervals within the core dated by ams radiocarbon measurements the first interval ca 975 bc 252 ad characterized by high abundances of calcidiscus leptoporus and gephyrocapsa muellerae i s thought to represent moderate water temperatures suggesting a transition from a warmer to a cooler period the second interval ca 252 1368 ad characterized by the dominance of coccolithus pelagicus helicosphaera carteri and syracosphaera spp and a high concentration of hexacosanol linked to terrestrial input is interpreted as having been a humid period with fluvial input the third interval ca 1368 ad 1950 is characterized by a high abundance of gephyrocapsa oceanica high alkenone values and low values of hexacosanol and is thought to represent a period dominated by oceanic conditions within the ria taking into account the ocean atmospheric system affecting the region studied here we propose an alternation in the mean state of north atlantic oscillation nao at millennial time scales awell developed upwelling system and an active ria ocean connection during the warmer interval i suggest a nao phase influenced by a hypsithermal period the occurrence of the humid and relatively warm interval ii is consistent with a negative phase in the nao as well as a relative restriction in ocean ria exchange interval iii which was drier and more productive again suggests the dominance of a positive phase in the nao with a more intense oceanic connection and more energized upwelling d 2004 elsevier b v all rights reserved

palynological evidence for climatic change anthropogenic activity and outflow of black sea water during the late pleistocene and holocene centennial to decadal scale records from the black and marmara seas abstract previous marine palynology studies of pollen and dinoflagellate cysts dinocysts in the black sea mediterranean corridor were made on short cores allowing only millennial century scale reconstruction of past climates we now describe pollen accumulation rates for 5 cores with eleven 14c ages over 30 000 years and new decadal scale data for a holocene core with fourteen 14c ages pollen influxes show pinus abies quercus forest steppe and deteriorating climate from 29 8 24 kyr bp then colder drier pre and post lgm conditions with artemisia cheno ams and ephedra that lasted through the bolling interstade deciduous oak returns by the younger dryas and rapidly expands followed by pistacia by 9 3 kyr bp foraminiferal 18o shows 4 c cooler than present late glacial summers and rapid holocene warming by 9 bp influxes from quercus cerris tilia fagus castanea ulmus shade ferns aquatics swamp plants and 18o indicate warm winters 5 c or more and year round precipitation 600 1000 mm not the dry conditions that would be required for black sea drawdown there is mid holocene expansion of carpinus evergreen quercus and pistacia walnut olive and cereal pollen suggest early cultivation attempts but no sustained farming before 4 5 kyr bp dinocyst assemblages show major changes traceable throughout the corridor variability in process length marks low diversity n 13 pleniglacial early holocene spiniferites cruciformis assemblages suggesting fluctuating salinity like the modern caspian sea with brackish to saline conditions 5 16 distributions of euryhaline cysts spiniferites mirabilis and spiniferites bentorii show the aegean and marmara seas were connected by 11 kyr bp and linked to black sea by 9 3 kyr bp there is no palynological evidence of either freshwater salinity

human climate interactions in the central mediterranean region during the last millennia the laminated record of lake butrint albania lake butrint 39 47 n 20 1 e is a ca 21 m deep coastal lagoon located in sw albania where finely laminated sediments have been continuously deposited during the last millennia the multi proxy analysis sedimentology high resolution elemental geochemistry and pollen of a 12 m long sediment core supported by seven ams radiocarbon dates and 137cs dating enable a precise reconstruction of the environmental change that occurred in the central mediterranean region during the last 4 5 cal kyrs bp sediments consist of triplets of authigenic carbonates organic matter and clayey laminae fluctuations in the thickness and or presence of these different types of seasonal laminae indicate variations in water salinity organic productivity and runoff in the lake s catchment as a result of the complex interplay of tectonics anthropogenic forcing and climate variability the progradation of the pavllo river delta favoured by variable human activity from the nearby ancient city of butrint led to the progressive isolation of this hydrological system from the ionian sea the system evolved from an open bay to a restricted lagoon which is consistent with archaeological data an abrupt increase in mass wasting activity between 1515 and 1450 bc likely caused by nearby seismic activity led to the accumulation of 24 homogenites up to 17 cm thick they have been deposited during the onset of finely laminated sedimentation which indicates restricted anoxic bottom water conditions and higher salinity periods of maximum water salinity biological productivity and carbonate precipitation coincide with warmer intervals such as the early roman warm period rwp 500 bc 0 ad the medieval climate anomaly mca 800 1400 ad and recent times after 1800 ad conversely lower salinity and more oxic conditions with higher clastic input were recorded during 1400 500 bc the late roman and the early medieval periods 0 800 ad and during the little ice age 1400 1800 ad hydrological fluctuations recorded in butrint are in phase with most central and western mediterranean records and correlate with nao variability in contrast opposite hydrological patterns have been recorded in the eastern balkans and the levant during the last millennium emphasizing a complex spatial variability in the region phases of maximum settlement intensity in butrint roman late antique coincide with warmer and or stable climate periods 0 800 ad and mca respectively indicating a long term influence of climatic conditions on human activities the late holocene sedimentary record of lake butrint demonstrates the complex interplay of climate variability tectonics and human impact in the recent evolution of coastal mediterranean regions

dinoflagellate cysts as indicators of water quality and productivity in british columbia estuarine environments abstract palynological analyses of 60 surface sediment samples from estuarine environments near vancouver island including the georgia strait gs the effingham eff and the seymour belize sb inlets were performed in order to document the distribution of dinoflagellate cyst assemblages and their relationship to hydrographic conditions productivity and nutrient concentrations we tested transfer functions using the analogue method and suggest that dinoflagellate cyst assemblages can be used to reconstruct primary productivity temperature and salinity the eff and sb inlets are characterized by a dominance of autotrophic taxa particularly operculodinium centrocarpum whereas the protoperidinioid and gymnodinial heterotrophic taxa such as quinquecuspis concreta and brigantedinium spp dominate the assemblages of the gs multivariate analysis shows that this distribution is closely linked to primary productivity sea surface temperature sst and spring silica concentration the abundance of autotrophic taxa in the eff and sb inlets is associated with high primary productivity and low summer sst indicating summer upwelling of coastal british columbia whereas the heterotrophic taxa that characterizes the gs assemblages are related to low productivity high summer sst and high silica concentration during spring multivariate analysis shows that the most important environmental parameters related to dinocyst distribution in the restricted embayment of the gs are distance to the shore distance to vancouver harbor spring sea surface salinity sss spring phosphate concentration and spring productivity the autotrophic taxa are generally more common in coastal and shallow waters but spiniferites ramosus and pentapharsodinium dalei show an opposite correlation to spring productivity and salinity p dalei is particularly abundant around vancouver harbor near highly urbanized shores and within the fraser river plume where salinity is low and spring productivity and continental runoff are high s ramosus shows its highest abundance on the western coast of gs protoperidinioid and gymnodinial cysts characterize distal zones within the central and southern gs that are associated with a mixture of brackish waters coming from the fraser river and deep upwelling waters entering the gs via juan de fuca strait the relationship between dinoflagellate cyst assemblages and primary productivity in these estuarine systems differs from that in oceanic and outer neritic zones where the abundance of heterotrophic taxa is commonly associated with upwelling and high productivity

the holocene gas system of the ria de vigo nw spain factors controlling the location of gas accumulations seeps and pockmarks abstract high resolution seismic profiles cored sediment gravity cores and vibro cores and radiocarbon data from suitable shell material were used to establish the stratigraphic context of gassy sediments in the ria de vigo mapping of seeps and pockmarks were compared with the stratigraphy of gassy sediment to ascertain the relationships in the ria de vigo three holocene seismic units were identified the first two uh 1 and uh 2 correspond to the transgressive systems tract tst and the third uh 3 corresponds to the highstand systems tract hst the presence of acoustic turbidity within the three seismic units indicates that generation of gas took place during the relative sea level rise that occurred after the younger dryas event i e during the tst and mainly during the hst the relative sea level variations are shown to be a major factor controlling the type fine vs coarse grained and distribution of facies lateral and vertical that generate and or allow gas accumulation or escape acoustic turbidity due to presence of free gas was recognized in the three holocene units with a total of 12 acoustic turbidity fields mapped in the ria de vigo no significant variations in the spatial distribution or extent of the gas fields or in their vertical location below the present sea bed have been observed during the seismic surveys carried out in the ria during the last decade furthermore gas escape from the sediment and active pockmark has been observed therefore we conclude that gas escape seeps pockmark generation and maintenance and methane formation are in equilibrium the combined analysis of high resolution seismic profiles sediment temperature pore water salinity and hydrostatic pressure revealed 1 a direct relationship between depth of free gas and hydrostatic pressure and 2 a direct link between sediment temperature and number of acoustic plumes from seabed to water column more acoustic plumes were detected in summer when the temperature of the sediment was higher than in winter indicating a seasonal variation of seeps within the ria salinity showed no significant differences between sea bottom water and sediment pore water and was therefore not a major factor controlling gas front variations

coherent high and low latitude climate variability during the holocene warm period a faunal record of sea surface temperature sst variations off west africa documents a series of abrupt millennial scale cooling events which punctuated the holocene warm period these events evidently resulted from increased southward advection of cooler temperate or subpolar waters to this subtropical location or from enhanced regional upwelling the most recent of these events was the little ice age which occurred between 1300 to 1850 a d when subtropical ssts were reduced by 3 to 4 c these events were synchronous with holocene changes in subpolar north atlantic ssts documenting a strong in phase link between millennial scale variations in high and low latitude climate during the holocene

palaeoproductivity changes and upwelling variability in the galicia mud patch during the last 5000 years geochemical and microfloral evidence theholocenepalaeoclimatichistoryofthegaliciancontinentalshelfhasbeeninvestigatedthrough theanalysesofdiatomremains othersiliceouscompounds biogenicsilica bsi andmetalscontentinamul tiproxyapproachtoagravitycorerecoveredfromthegaliciamudpatch nwiberianpeninsula coveringthe last 5000 years downcore changes in diatom assemblages composition and abundance reflect changes in diatomproductionrelatedtolong short termvariationsinclimate regionaloceanography upwellingstrength and river influx off the coast of nw spain and portugal palaeoclimatic variability was related to the relative strengths and position of the azores high and iceland low pressure cells metals and microflora fluctuations are interpreted as changes in the riverine influence and upwelling intensity paced by oceanographic atmos pheric and climatic changes lack of diatoms between 4700 3300 and 1800 1200 cal yr bp could be linked to early diagenetic processes taking place in the sediment after burial biogenic barium baexcess metals and diatomassemblages showageneralincreaseofmarineproductivityforthelast1200cal yrbp between800 and500cal yrbphighproductionofthemicrofloraistriggeredbyinfluxofriver derivednutrientsundercon ditionsofswwindsandstormsresultingfromanaonegative likephase thebiosiliceousandgeochemical signatures of sediments from the last 500 cal yr bp indicate conditions of enhanced upwelling and increased

wind regimes and aeolian transport in the great basin u s a abstract the modern great basin of the interior western united states is characterized by surface winds with considerable spatial and temporal variabilities wind records from the second half of the 20th century for 12 great basin localities analyzed with standard aeolian sediment transport methods developed elsewhere in the world reflect this complexity the drift potential dp for aeolian deposits is generally moderate dp 200 400 in the western great basin and weak dp 300 at the eastern edge of the great basin where the dominant prevailing wind direction is south southwesterly both dp and resultant drift direction rdd are consistent with synoptic meteorological observations of the evolution of cold fronts in the great basin meteorological observations show that effective winds to produce dunes are most commonly the result of late winter early spring cyclogenesis there has been considerable temporal variability of dp in the latter half of the 20th century most of the great basin has experienced decreasing wind strength since 1973 consistent with recent studies of wind strength in north america and elsewhere dune morphology matches both localized rdd and temporal variations in dp reasonably well in the great basin the results demonstrate that local topography can have an important influence on wind directionality thus providing a cautionary note on the interpretation of dune morphology in the paleoclimatic and stratigraphic record

arabian sea surface winds and ocean transports determined from ers 1 scatterometer satellite scatterometer wind velocity measurements are a new source of data for studies of seasonal to interannual ocean atmosphere interactions in the arabian sea where the largest and steadiest wind speeds occur in northern summer three satellite wind velocity data products named cmod4 fd and ifr2 all created from radar backscatter measured by the first european remote sensing satellite ers 1 were compared to moored buoy wind measurements recorded in the central arabian sea during october 1994 to october 1995 orthogonal regression analysis of 74 collocations indicated ifr2 winds were more representative of buoy winds compared to cmod4 and fd ifr2 winds during 1995 are described including the time of monsoon onset and the path of the somali jet monthly mean vertical transport across the bottom of the ekman layer of the arabian sea north of 8 n meridional ekman transport along 8 5 n and sverdrup transport along 8 5 n were computed with ifr2 data from may 1992 to may 1996 during the 1992 1995 june september southwest monsoon upwelling into the ekman layer of the arabian sea occurred at a mean rate of 3 4 sv 1 sv 106 m3 s 1 which was one third smaller than the volume transport exiting within the ekman layer across the southern boundary of the arabian sea and the southward sverdrup transport was 15 sv during the 1992 1996 december march northeast monsoon nearly 5 sv sank below the bottom of the ekman layer 4 sv entered the arabian sea in the ekman layer and the sverdrup transport was negligible year to year transport variations were small

daily evolution in dust and black carbon content snow grain size and snow albedo during snowmelt rocky mountains colorado light absorbing impurities lai initiate powerful snow albedo feedbacks yet due to a scarcity of observations and measurements lai radiative forcing is often neglected or poorly constrained in climate and hydrological models to support physically based modeling of lai processes daily measurements of dust and black carbon bc stratigraphy optical grain size snow density and spectral albedo were collected over the 2013 ablation season in the rocky mountains co surface impurity concentrations exhibited a wide range of values 0 02 6 0 mg g 1 pptw with 98 of mass being deposited by three episodic dust events in april even minor dust loading initiated albedo decline and the negative relationship between dust concentrations and albedo was log linear as melt progressed individual dust layers coalesced and emerged at the snow surface with minimal mass loss to meltwater scavenging the observations show that the convergence of dust layers at the surface reduced albedo to 0 3 and snow depth declined 50 faster than other years with similar depth but less dust the rapid melt led to an unexpected reduction in both grain size and density in uppermost surface layers bc concentrations co varied with dust concentrations but were several orders of magnitude lower

multidecadal mobility of the north atlantic oscillation abstractthe north atlantic oscillation nao is one of the most important modes of variability in the global climate system and is characterized by a meridional dipole in the sea level pressure field with centers of action near iceland and the azores it has a profound influence on the weather climate ecosystems and economies of europe greenland eastern north america and north africa it has been proposed that around 1980 there was an eastward secular shift in the nao s northern center of action that impacted sea ice export through fram strait independently it has also been suggested that the location of its southern center of action is tied to the phase of the nao both of these attributes of the nao have been linked to anthropogenic climate change here the authors use both the one point correlation map technique as well as empirical orthogonal function eof analysis to show that the meridional dipole that is often seen in the sea level pressure field over the north atlantic is not purely the

geomorphic and land cover identification of dust sources in the eastern great basin of utah u s a abstract this study identifies anthropogenically disturbed areas and barren playa surfaces as the two primary dust source types that repeatedly contribute to dust storm events in the eastern great basin of western utah u s a this semi arid desert region is an important contributor to dust production in north america with this study being the first to specifically identify and characterize regional dust sources from 2004 to 2010 a total of 51 dust event days deds affected the air quality in salt lake city ut modis satellite imagery during 16 of these deds was analyzed to identify dust plumes and assess the characteristics of dust source areas a total of 168 plumes were identified and showed mobilization of dust from quaternary deposits located within the bonneville basin this analysis identifies 4 major and 5 secondary source areas for dust in this region which produce dust primarily during the spring and fall months and during moderate or greater drought conditions with a palmer drought index pdi of 2 or less the largest number of observed dust plumes 60 of all plumes originated from playas ephemeral lakes and are classified as barren land cover with a silty clay soil sediment surface playa surfaces in this region undergo numerous recurrent anthropogenic disturbances including military operations and anthropogenic water withdrawal anthropogenic disturbance is necessary to produce dust from the vegetated landscape in the eastern great basin as evidenced by the new dust source active from 2008 to 2010 in the area burned by the 2007 milford flat fire this fire was the largest in utah s history due to extensive cover of invasive cheatgrass bromus tectorum along with drought conditions however dust mobilization from the milford flat burned area was limited to regions that had been significantly disturbed by post fire land management techniques that consisted of seeding followed by chaining or tilling of the soil dust storms in the eastern great basin negatively impact air quality and transportation in the populated regions of utah this study details an improved forecasting protocol for dust storm events that will benefit transportation planning and improve public health

high resolution dinoflagellate cyst record of environmental change in effingham inlet british columbia canada over the last millennium abstract we present a high resolution sedimentary record of dinoflagellate cysts spanning the last 900 years recovered from effingham inlet a glacial fjord on the west coast of vancouver island canada the combination of seasonal coastal upwelling supporting high levels of marine primary productivity in surface waters together with restricted bottom water circulation in the silled fjord fosters the preservation of laminated sediments in the inner basin of effingham inlet geochemical data are used to assess the sedimentary facies of the core which is composed primarily of laminated units 50 2 occasionally interrupted by seismites 39 5 and homogenous units 10 2 the chronology of the 2 m long core is based on varve counting and fifteen 14c dates and is anchored by a seismite previously dated at ad 1946 the dinoflagellate cyst assemblages are diverse total of 47 taxa abundant average concentrations of 102 900 cyst g 1 of dry sediment and characterized by a proportionally equal contribution of autotrophic and heterotrophic cyst taxa in most samples overall cyst assemblages are characterized by operculodinium centrocarpum 36 2 accompanied by brigantedinium spp 18 0 and dubridinium spp 6 6 multivariate analyses are used to extract the dominant patterns of variability in autotrophic and heterotrophic dinoflagellate cyst assemblages separately and help in identifying the temperature and primary productivity gradients encoded in the cyst sedimentary record in this particular estuary specific intervals identified in the dinoflagellate cyst record are interpreted to represent the local expression of the medieval climate anomaly from the base of the record ad 1090 to 1230 the little ice age ad 1230 to late 19th century and warming in the second half of the 20th century the timing of these intervals are consistent with the regional paleoclimate and help constrain past climatic and oceanographic variability on the west coast of vancouver island the origin of homogenous units in the sedimentary record of effingham inlet and paleoseismicity in the region are also discussed

a global merged land air sea surface temperature reconstruction based on historical observations 1880 1997 abstract a merged land air sea surface temperature reconstruction analysis is developed for monthly anomalies the reconstruction is global and spatially complete reconstructed anomalies damp toward zero in regions with insufficient sampling error estimates account for the damping associated with sparse sampling and also for bias uncertainty in both the land and sea observations averages of the reconstruction are similar to simple averages of the unanalyzed data for most of the analysis period for the nineteenth century when sampling is most sparse and the error estimates are largest the differences between the averaged reconstruction and the simple averages are largest sampling is always sparse poleward of 60 latitude and historic reconstructions for the polar regions should be used with caution

palynological evidence for late quaternary climate and marine primary productivity changes along the california margin a high resolution sedimentary record of dinoflagellate cysts from ocean drilling program hole 1017e off point conception california margin reflects how marine primary productivity has changed in response to major shifts in climate and ocean circulation along the california margin over the past 42 kyr throughout the studied sequence dinoflagellate cyst assemblages are dominated by upwelling related taxa signifying the continued presence of coastal upwelling on the margin during the late quaternary the cyst record suggests that marine primary productivity was enhanced during the holocene and bolling and to a lesser extent during the late glacial and most dansgaard oeschger events while an apparent reduction in primary productivity can be seen during the younger dryas the best analogue technique based on a modern dinoflagellate cyst assemblage database from the northeast pacific was used for quantitative reconstruction of past sea surface conditions it points to dynamic changes in annual marine primary productivity 235 331 g c m 2 yr 1 and sea surface temperature 10 1 12 6 c in winter 13 1 14 3 c in summer while sea surface salinity appears to be confined to a narrower range 32 9 33 4 in summer our results also indicate noticeable climate variability during the holocene in this region

analysis of a 3 year meteorological record from the ablation zone of morteratschgletscher switzerland energy and mass balance since 1 october 1995 an automatic weather station has been operated on the tongue of morteratschgletscher switzerland the station stands freely on the ice and sinks with the melting glacier surface it is located at 2100 m a s l and measures air temperature wind speed and direction incoming and reflected solar radiation pressure and snow temperature a sonic ranger mounted to stakes drilled into the ice measures surface height from which melt rates and snow accumulation can be derived in this paper the data for the period 1 october 1995 to 30 september 1998 are used to evaluate the surface energy balance the turbulent energy fluxes are calculated with the bulk method the turbulent exchange coefficient c h is used as a control parameter with c h 0 00127 the calculated melt equals the observed melt which is 17 70 m w e over the 3 years when averaged over the time when melting occurs i e 35 of the time the mean surface heat flux equals 191 w m 2 net shortwave radiation contributes 177 w m 2 net longwave radiation 25 w m 2 the sensible heat flux 31 w m 2 and the latent heat flux 8 w m 2