importance of peakedness in sea surface slope measurements and applications we recall the simple statistical concept that non gaussian distribution peakedness results from the compounding of random processes this idea is applied to observations and analysis of sea surface slopes as inferred using optical and microwave scattering measurements our study emphasizes the importance of identifying and quantifying the distribution variance and kurtosis from observations data are shown to indicate consistently non gaussian peakedness to indicate the need to report at least two parameters in an even order analysis and to indicate near equivalence between radar and optical data physical interpretation for observed infrequent steep slopes is given via compounding statistical processes where normally distributed short scale waves are modulated because of random fluctuations mainly associated with the underlying long wave field implications of non gaussian peakedness are provided for altimeter backscatter theory and for modeling wave breaking probability

gnss r nonlocal sea state dependencies model and empirical verification global navigation satellite system reflectometry gnss r is an active bistatic remote sensing technique operating at l band frequencies gnss r signals scattered from a rough ocean surface are known to interact with longer surface waves than traditional scatterometery and altimetry signals a revised forward model for gnss r measurements is presented which assumes an ocean surface wave spectrum that is forced by other sources than just the local near surface winds the model is motivated by recent spaceborne gnss r observations that indicate a strong scattering dependence on significant wave height even after controlling for local wind speed this behavior is not well represented by the most commonly used gnss r scattering model which features a one to one relationship between wind speed and the mean square slope of the ocean surface the revised forward model incorporates a third generation wave model that is skillful at representing long waves an anchored spectral tail model and a gnss r electromagnetic scattering model in comparisons with the spaceborne measurements the new model is much better able to reproduce the empirical behavior

holocene climate variability and change a data based review the holocene thermal maximum with peak temperatures prior to 7 ka bp is mostly accentuated in the northern hemisphere still visible in the southern hemisphere and possibly did not exist in the tropics between this period and the modern warming a remarkable negative temperature trend occurred in the northern hemisphere which was probably the effect of a decreasing orbital induced insolation during the boreal summer on average the northern hemisphere humidity precipitation records do not show any significant trend a mechanistic explanation for the multi decadal to century scale holocene cold relapses which mainly occurred in the atlantic european regions exists for only the early holocene cooling events which are probably the result of a collapse of the meridional overturning circulation owing to freshwater outbursts from the laurentide ice sheet possibly the late holocene cold events after c 4 ka bp are influenced by the covarying influence of major tropical volcanic eruptions and grand solar minima

a deglacial middle holocene record of biogenic sedimentation and paleoproductivity changes from the northern norwegian continental shelf 1 the relative proportions of marine organic carbon and biogenic carbonate in a high resolution record from a glacial trough on the northern norwegian continental shelf were used to decipher changes in biogenic sedimentation and paleoproductivity from the last deglaciation to the middle holocene decadal scale to century scale oscillations in biogenic sedimentation and surface ocean productivity recorded in the andfjorden sediments are synchronous with abrupt climate changes in open oceanic and atmospheric regimes of the high northern latitudes following several fluctuations during the bolling allerod interstadial the most dramatic drop in marine organic carbon and biogenic carbonate proportions occurred during the younger dryas however many short term and low amplitude events during the preboreal and the holocene have also affected biogenic sedimentation in the outer andfjorden apparently these abrupt changes in biogenic sedimentation were caused by the suppression of a potential upwelling center in the outer andfjorden by variable atlantic water inflow over the past 14 000 years the adjustment of decadal high productivity coastal systems to freshwater forced multiple cooling events during the late glacial to middle holocene highlights the impact of global climate changes on the climate sensitive local ecosystems off coastal norway

pelagic processes and vertical flux of particles an overview of a long term comparative study in the norwegian sea and greenland sea pelagic processes and their relation to vertical flux have been studied in the norwegian and greenland seas since 1986 results of long term sediment trap deployments and adjoining process studies are presented and the underlying methodological and conceptional background is discussed recent extension of these investigations at the barents sea continental slope are also presented with similar conditions of input irradiation and nutrient conditions the norwegian and greenland seas exhibit comparable mean annual rates of new and total production major differences can be found between these regions however in the hydrographic conditions constraining primary production and in the composition and seasonal development of the plankton this is reflected in differences in the temporal patterns of vertical particle flux in relation to new production in the euphotic zone the composition of particles exported and in different processes leading to their modification in the mid water layers

investigating the impact of anthropogenic land use on a hemiboreal lake ecosystem using carbon nitrogen ratios and coupled optical emission spectroscopy anthropogenic impacts on lake ecosystems have increased substantially towards the present however the strength and timing in most cases are not evaluated in detail missing valuable information on the response and recovery of an aquatic system in this study we use the sediment total organic carbon total nitrogen ratio c n and inductively coupled optical emission spectroscopy icp oes elements and the available information about the biological processes to explore anthropogenic land use impact on the lake ecosystem as a case study we selected a hemiboreal lake trik tas latvia ne europe the pearson correlation was used to statistically test the correlations of all variables our results show that the c n ratio lowered immediately with the onset of crop cultivation at 500 bce extensive forest clearance and an abrupt increase in land use are reflected through the associated chemical elements from icp oes and the increasing presence of herbivore dung spores since 1200 ce these changes concur with the excess of fish remains suggesting a decrease in fish populations interestingly anthropogenic land use driven erosion and accompanied calcium carbonate caco3 matter influx favoured the abundance of chara spp in lake trik tas since 500 ce which currently forms the protected specific habitat type h3140 of the european union at present specific submerged macrophyte chara habitat type diminished almost entirely due to increased nutrient input phytoplankton blooming hypertrophic conditions and reduced light availability the continued land use practices led to a switch in organic matter source in the lake from macrophytes to solely algal origin the current study underlines the need of additional methods used to detect the sensitivity of lake ecosystem to external disturbances such as minor anthropogenic land use that might not necessarily be apparent in more traditional analyses such as palynology

dynamics of atlantic water advection to the norwegian greenland sea a time slice record of carbonate distribution in the last 300 ky abstract short term variability in volume and configuration of atlantic water advection to the norwegian greenland sea ngs has recently been identified as a new and significant element for northern hemisphere glacial interglacial climatic fluctuations the amount of salt heat and moisture transferred by atlantic waters to the high arctic effectively influences northern hemisphere climates and is critical for the overall oceanic turnover rate in particular determining the extent and duration of atlantic water intrusions in the ngs is essential because of 1 its effect on the climate of the nordic continents and 2 its trigger function on the stability of the ice sheets with a weak inflows of atlantic water during glacials promoting an increase in ice volume by moisture supply to polar areas and b positive feed back mechanisms of atlantic water intrusions during ice sheet decay in this study the dynamics of surface water mass regimes in the ngs have been reconstructed for the past 300 ky by means of time slice compilations of calcium carbonate distribution and micropaleontologic proxies in addition carbonate preservation records are used to quantify deep water ventilation and production rates in contrast to the climap scenario but in accordance with many recent publications results of this study indicate that atlantic water advection was also a common feature during most glacial periods but varied strongly in volume and configuration significant modes recognized are 1 the full interglacial mode with a wide inflow of warm atlantic waters covering a broad area in the eastern sector of the ngs and extending far north combined with excellent carbonate preservation and very efficient deep water formation stages 1 and 5 5 1 2 the moderate interglacial mode with a rather small extension of atlantic waters along a narrow corridor in the southeastern sector of the ngs but still very efficient deep water exchange stages 9 isotopic events 7 5 7 3 7 1 5 3 and 5 1 3 pronounced cool phases during interglacials with only a very narrow inflow of atlantic waters into the southeastern ngs while the coastal areas off norway were still affected by iceberg drift substages 7 4 and 5 2 carbonate preservation records indicate ongoing deep water formation in the ngs 4 the normal glacial mode characterized by a variable but persistent inflow of cool temperate atlantic water lower stage 8 repetitively during stages 6 4 3 1 and 2 carbonate preservation records indicate ongoing deep water formation in the ngs 5 short glacial and deglacial periods characterized by episodic high inputs of ird evidenced by a wide coverage of diamicton deposition and strong carbonate dissolution e g episodically within stages 10 6 and 2 the 6 5 4 3 and 2 1 transitions some of these ngs diamicton layers correlate with heinrich layers in the north atlantic but generally ngs diamicton layers occur more frequently than heinrich layers the role of atlantic water influence during these events remains enigmatic but atlantic water influence is frequently found just above and below these sections a scenario with rapid ice sheet disintegration induced by atlantic water advection via increase of the thermal regime along the ice margin possibly triggered by small scale sea level rise might be envisaged more obviously the short term cessation of deep water formation in the ngs as evidenced by the dissolution spikes may be correlated with contemporaneous ventilation minima in the north atlantic

itrax description and evaluation of a new multi function x ray core scanner a new automated multi function core scanning instrument named itrax has been developed that records optical radiographic and elemental variations from sediment half cores up to 1 8 m long at a resolution as fine as 200 m an intense micro x ray beam focused through a flat capillary waveguide is used to irradiate samples to enable both x radiography and x ray fluorescence xrf analysis data are acquired incrementally by advancing a split core via a programmable stepped motor drive through the flat rectangular section x ray beam traditional xrf determination of element composition in sediments provides high quality data but it takes a considerable time and normally consumes gram quantities of material that is often only available in limited quantities the itrax core scanner non destructively collects optical and x radiographic images and provides high resolution elemental profiles that are invaluable for guiding sample selection for further destructive detailed sampling this paper presents a description of the construction characteristics and capabilities of the itrax system high resolution itrax data obtained from sediment cores are also presented and compared with results from traditional wavelength dispersive xrf analysis at lower resolution finally some recent technical developments linked to the second generation itrax are presented

climate change vegetation development and lake level fluctuations in lake purwin ne poland during the last 8600 cal bp based on a high resolution plant macrofossil record and stable isotope data δ13c and δ18o abstract this paper presents a history of the vegetation in lake purwin ne poland and its catchment along with water level changes for the last 8600 cal bp the reconstructions are based on a high resolution plant macroremains analysis and the stable isotope record in authigenic carbonates a fine fraction that is precipitated within the epilimnion of the lake the stable isotope records suggest that the lake had throughflow during the holocene and that isotope data can therefore be used in palaeoclimatic reconstructions the 18o values record the thermal maximum of the holocene and the subsequent cooling of the upper holocene water level changes and the history of the lake s productivity are both recorded in the 13c values a chronology is established using radiocarbon dating of terrestrial plant macrofossils the vegetation and water levels in lake purwin reflect regional climate changes the combination of the lithology along the sedimentary sequence the results of the plant macroremains analysis and the isotope data allowed several alternating periods of high 8600 7300 6500 5200 4400 3500 and 3000 950 cal bp and low 7300 6500 5200 4400 3500 3000 and 950 to 59 cal bp water stands to be distinguished in lake purwin low water levels are indicated by sediments that are enriched in coarse plant detritus seeds of rubus ideaus fruits of uritca dioica and more macroremains of alnus glutinosa and rushes

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

holocene climatic instability a prominent widespread event 8200 yr ago the most prominent holocene climatic event in greenland ice core proxies with approximately half the amplitude of the younger dryas occurred 8000 to 8400 yr ago this holocene event affected regions well beyond the north atlantic basin as shown by synchronous increases in windblown chemical indicators together with a significant decrease in methane widespread proxy records from the tropics to the north polar regions show a short lived cool dry or windy event of similar age the spatial pattern of terrestrial and marine changes is similar to that of the younger dryas event suggesting a role for north atlantic thermohaline circulation possible forcings identified thus far for this holocene event are small consistent with recent model results indicating high sensitivity and strong linkages in the climatic system

correction of the sea state impact in the l band brightness temperature by means of delay doppler maps of global navigation satellite signals reflected over the sea surface this paper presents an efficient procedure based on 2 d convolutions to obtain delay doppler maps ddms of global navigation satellite signals reflected gnss r over the sea surface and collected by a spaceborne receiver two ddm derived observables area and volume are proposed to link the sea state induced brightness temperature to the measured normalized ddm finally the requirements to use global positioning system reflectometry to accurately correct for the sea state impact on the l band brightness temperature quantization levels decimation truncation and noise impact are analyzed in view of its implementation in the passive advanced unit instrument of the spanish earth observation satellite seosat ingenio project

late quaternary expansion of norway spruce picea abies l karst in europe according to pollen data abstract lateglacial and holocene expansion of norway spruce picea abies l karst in europe is reconstructed in steps of 1000 radiocarbon years on the basis of pollen data collected from literature and databases pollen thresholds for the lateglacial of 0 1 2 5 and 10 and for the holocene of 2 were used spruce pollen representation and limitations of pollen data are discussed we assume that the 2 threshold tracks the advance of the main spruce front but might fail to detect small populations or those present in low density the history of spruce expansion was distinctly different in northern and southern parts of its range 1 in ne europe spruce expanded during the allerod reaching southwards to n byelorussia during the younger dryas spruce populations contracted north of ca 60 n but expanded strongly in the region approximately 53 60 n 23 32 e where they declined at the beginning of the holocene we infer that the lateglacial expansion in ne europe concerned mainly p abies subsp obovata 2 holocene expansion in n europe concerned mainly p abies subsp abies southward expansion within the northern range is continuing to the recent millennium 3 in central europe spruce expanded vigorously during the allerod contracted or stagnated during the younger dryas and then strongly re expanded during the preboreal following the simple expectation that climatic warming had a positive impact on its development 4 holocene westward and northward expansion of spruce in its southern range central europe was rapid 10 8 ka 14 c bp very slow 8 6 ka 14 c bp and rapid 6 5 ka 14 c bp when the present day western limits were reached 5 the 2 spruce pollen threshold is too high to detect the fact that the northern and southern ranges of spruce have joined in the holocene the persistence of low spruce abundance in the transitional area is explained mainly by the strong anthropogenic deforestation ever since spruce grew there

the last 18 kyr fluctuations in norwegian sea surface conditions and implications for the magnitude of climatic change evidence from the north sea a combined record of three cores spanning the last 18 kyr from the northern north sea is investigated for content of benthic and planktonic foraminifera and stable oxygen isotopes the paleoenvironmental development through this time period shows an early deglaciation 18 14 4 ka and the younger dryas 12 7 11 5 ka characterized by arctic polar conditions and increased ice rafting in the norwegian channel during the bolling allerod period warm sea surface temperature 9 c conditions similar to present conditions are inferred while bottom waters stayed cold 0 1 c with normal salinity the bolling allerod period is interrupted twice at 13 9 13 6 ka older dryas and at 13 0 12 8 ka inter allerod cooling period by reductions in sea surface temperatures and increased sea ice cover the beginning of the holocene period is marked by increases in surface and bottom water temperature superimposed on the broad climatic changes through the holocene a series of short lived oscillations in the ocean circulation are recorded the amplitude of these holocene events appears larger in the early holocene prior to 8 ka than compared with the remaining part of the holocene this amplification can possibly be attributed to a general increased freshwater budget in the north atlantic at this time during the final stages of the deglaciation of the laurentide and scandinavian ice sheets

sequential processing of gnss r delay doppler maps to estimate the ocean surface wind field spaceborne global navigation satellite system reflectometry gnss r measurements of ocean winds present a challenge because the surface wind speed cannot be assumed homogeneous over the large glistening zone observable from orbit the 25 km resolution requirement of the cyclone gnss cygnss mission limits wind speed retrievals to using only a small fraction of the delay doppler map ddm near the specular point this paper presents a new method to invert a larger portion of the ddm and estimate the wind field within a swath defined by the maximum delay an extended kalman filter ekf is applied to combine a series of ddms and estimates the wind speed on a uniformly gridded ocean surface exploiting the large overlap between sequential looks wind retrievals at the specular point using simulated data generated using wind fields from two hurricanes danielle and earl 2010 were found to meet the cygnss measurement requirements 2 m s for u 20 m s and perform better than a typical single point observable wind retrievals were also found to meet these requirements below 20 m s within a 90 km swath and meet them for hurricane force winds 17 times 11 ddm demonstrating benefits of sequential processing within a limited data budget delay doppler ambiguities introduced noticeable artifacts in circumstances where the wind varies asymmetrically within the observed 90 times 90 km surface area but did not appear to affect specular point wind retrievals

detection and processing of bistatically reflected gps signals from low earth orbit for the purpose of ocean remote sensing we will show that ocean reflected signals from the global positioning system gps navigation satellite constellation can be detected from a low earth orbiting satellite and that these signals show rough correlation with independent measurements of the sea winds we will present waveforms of ocean reflected gps signals that have been detected using the experiment onboard the united kingdom s disaster monitoring constellation satellite and describe the processing methods used to obtain their delay and doppler power distributions the gps bistatic radar experiment has made several raw data collections and reflected gps signals have been found on all attempts the down linked data from an experiment has undergone extensive processing and ocean scattered signals have been mapped across a wide range of delay and doppler space revealing characteristics which are known to be related to geophysical parameters such as surface roughness and wind speed here we will discuss the effects of integration time reflection incidence angle and examine several delay doppler signal maps the signals detected have been found to be in general agreement with an existing model based on geometric optics and with limited independent measurements of sea winds a brief comparison is presented here these results demonstrate that the concept of using bistatically reflected global navigation satellite systems signals from low earth orbit is a viable means of ocean remote sensing

simulation of l band bistatic returns from the ocean surface a facet approach with application to ocean gnss reflectometry we present the implementation of a facet based simulator to investigate the forward scattering of l band signals from realistic sea surfaces and its application to spaceborne ocean global navigation satellite system gnss reflectometry this approach provides a new flexible tool to assess the influence of the ocean surface roughness on scattered gnss signals the motivation stems from the study by clarizia which revealed significant differences between delay doppler maps ddms obtained from uk dmc satellite data and ddms simulated with the zavorotny voronovich z v model here the scattered power and polarization ratio pr are computed for explicit 3 d ocean wave fields using a novel implementation of the kirchhoff approximation ka which we call the facet approach fa we find that the fa is consistent with the full ka and the geometrical optics go used in the z v model while being less computationally expensive than the ka and able to represent polarization effects not captured by the go instantaneous maps of the bistatic normalized radar cross section computed with the fa show clear patterns associated with the underlying waves the wave field is particularly visible in the pr indicating that the scattering is generally dominated by the hh component particularly from ocean wave troughs polarization effects show for the first time a strong correlation to the explicit sea surface from which the scattering originated ddms of the scattered power computed with the fa reveal patchy patterns and power distributions that differ from those obtained with z v and show closer similarities with observed ddms from uk dmc

was it terra desolata conquering and colonizing the medieval prussian wilderness in the context of climate change pollen non pollen palynomorphs charcoal and geochemical analyses of sediments from lakes salet and ruskowiejskie ne poland were used to reconstruct vegetation changes in the former galindia territory old prussia related to human activity and the climatic instability of the medieval period among archaeologists and historians there is a widespread opinion that the permanent transformations of the environment in prussia south eastern baltic region began not earlier than after its conquest by the teutonic order and resulted from its economic activity and intensive colonization the impact of previous inhabitants of this land on the environment has been considered as definitely weak our results provide entirely contrasting evidence and demonstrate that strong and permanent deforestation started as early as in the early 11th century ad in the pre teutonic order time and were associated with the economic activity of the prussian galinditae tribes in this paper we also discuss a possible interpreta

generalized linear observables for ocean wind retrieval from calibrated gnss r delay doppler maps the cyclone global navigation satellite system cygnss mission will use global navigation satellite system reflectometry to measure ocean surface winds in and near the hurricane inner core including regions beneath the eye wall which could not previously be measured from space due to intense precipitation the cygnss constellation will consist of eight small satellite observatories in 500 km circular orbits at an inclination of 35 cygnss observatories will receive both direct and reflected signals from global positioning system satellites direct signals will be used both for conventional navigation of the observatory positions and for calibration of the incident signal power reflected signals respond to ocean surface roughness from which wind speed is retrieved this is observed as changes in a delay doppler map ddm a generalized observable which is defined as a linear combination of the ddm samples is optimized using three different methods maximum signal to noise ratio minimum variance of the wind speed and principal component analysis pca performance of each of these three approaches is compared with each other and with that of the baseline level 2 retrievals defined for cygnss ddm average leading edge slope and the minimum variance combination of both pca is found to have the best performance

a 1400 year high resolution record of atmospheric circulation over the north atlantic and asia major ion series developed from new subannual scale sampling of an ice core from central greenland are calibrated with instrumental series of atmospheric sea level pressure recording major marine icelandic low and terrestrial siberian high atmospheric circulation systems to provide proxy records of atmospheric circulation over the past 1400 years examination of the proxy records reveals major changes in behaviour of these systems c ad 1400 multidecadal and centennial scale periodic components characterization of mean sea level pressure anomaly fields during the little ice age and the mediaeval warm period the potential role of solar forcing coupled ocean atmosphere associations and a perspective within which the characteristics of instrumental era climate can be assessed

using ddm asymmetry metrics for wind direction retrieval from gps ocean scattered signals in airborne experiments reflectometry of signals of opportunity such as those emitted by a global navigation satellite system known as gnss r has been developed over the past years as a technique with great potential for ocean scatterometry among other applications different approaches have been proposed to use gnss r for remote sensing of ocean surface roughness one of them is based on deriving some descriptor metric from the measured delay doppler map ddm and directly relating it to a geophysical property of the scattering surface for instance different descriptors have been proposed in the literature to measure the ddm spreading caused by the increase in ocean surface mean square slopes due to surface winds in this paper a new descriptor based on the ddm is proposed for wind direction retrieval this descriptor designated as the skewness angle 1 skew measures the asymmetry in the ddm power distribution along the doppler frequency axis and it was modeled as a function of wind direction by means of a simulation study then that model was validated using real gnss r data from an airborne experiment after validation the ddm skewness model was successfully used for wind direction retrieval with a resulting rms error on the order of 20

5 cm precision aircraft ocean altimetry using gps reflections 1 we present the first two aircraft global positioning system gps reflection altimetry measurements the most precise gps ocean altimetry measurement and demonstrate the altimetric precision and spatial resolution necessary to map mesoscale eddies our first experiment demonstrated a 14 cm precision single satellite ocean altimetry measurement while our more recent experiment demonstrates 5 cm altimetric precision with 5 km spatial resolution the new results show significant improvement over our previous effort due to improved modeling greater aircraft altitudes and velocities improved receiver positioning and better experimental control plans to further reduce speckle and refine models to obtain 5 cm altimetric accuracy are presented

a chrysophyte based quantitative reconstruction of winter severity from varved lake sediments in ne poland during the past millennium and its relationship to natural climate variability abstract chrysophyte cysts are recognized as powerful proxies of cold season temperatures in this paper we use the relationship between chrysophyte assemblages and the number of days below 4 c db4 c in the epilimnion of a lake in northern poland to develop a transfer function and to reconstruct winter severity in poland for the last millennium db4 c is a climate variable related to the length of the winter multivariate ordination techniques were used to study the distribution of chrysophytes from sediment traps of 37 low land lakes distributed along a variety of environmental and climatic gradients in northern poland of all the environmental variables measured stepwise variable selection and individual redundancy analyses rda identified db4 c as the most important variable for chrysophytes explaining a portion of variance independent of variables related to water chemistry conductivity chlorides k sulfates which were also important a quantitative transfer function was created to estimate db4 c from sedimentary assemblages using partial least square regression pls the two component model pls 2 had a coefficient of determination of r cross 2 0 58 with root mean squared error of prediction rmsep based on leave one out of 3 41 days the resulting transfer function was applied to an annually varved sediment core from lake abinskie providing a new sub decadal quantitative reconstruction of db4 c with high chronological accuracy for the period ad 1000 2010 during medieval times ad 1180 1440 winters were generally shorter warmer except for a decade with very long and severe winters around ad 1260 1270 following the ad 1258 volcanic eruption the 16th and 17th centuries and the beginning of the 19th century experienced very long severe winters comparison with other european cold season reconstructions and atmospheric indices for this region indicates that large parts of the winter variability reconstructed db4 c is due to the interplay between the oscillations of the zonal flow controlled by the north atlantic oscillation nao and the influence of continental anticyclonic systems siberian high east atlantic western russia pattern differences with other european records are attributed to geographic climatological differences between poland and western europe low countries alps striking correspondence between the combined volcanic and solar forcing and the db4 c reconstruction prior to the 20th century suggests that winter climate in poland responds mostly to natural forced variability volcanic and solar and the influence of unforced variability is low

scattering of gps signals from the ocean with wind remote sensing application a theoretical model that describes the power of a scattered global positioning system gps signal as a function of geometrical and environmental parameters has been developed this model is based on a bistatic radar equation derived using the geometric optics limit of the kirchhoff approximation the waveform i e the time delayed power obtained in the delay mapping technique depends on a wave slope probability density function which in turn depends on wind waveforms obtained for aircraft altitudes and velocities indicate that altitudes within the interval 5 15 km are the best for inferring wind speed in some regimes an analytical solution for the bistatic radar equation is possible this solution allows converting trailing edges of waveforms into a set of straight lines which could be convenient for wind retrieval a transition to satellite altitudes together with satellite velocities makes the peak power reduction and the doppler spreading effect a significant problem for wind retrieval based on the delay mapping technique at the same time different time delays and different doppler shifts of the scattered gps signal could form relatively small spatial cells on sea surface suggesting mapping of the wave slope probability distribution in a synthetic aperture radar sar fashion this may allow more accurate measurements of wind velocity and wind direction

2 cm gps altimetry over crater lake dierences in electromagnetic path delay be tween direct global positioning system gps signals and those reflected from the surface of crater lake have led to lake surface height estimates with 2 cm precision in 1 sec ond this is the rst high precision altimetric demonstra tion with gps from sucient altitude 480 m to probe fundamental experimental errors which bear on future air and spaceborne passive gps altimetry it also serves as the rst demonstration of a new approach to altimetric remote sensing in the coastal region an area that is poorly mea sured by conventional radar altimetry time series analy sessuggest thattroposphericandthermalnoisefluctuations dominate the altimetric error in this experiment estimat ing the dierential delay from several simultaneously visi ble satellites may enable tropospheric error estimation and correction thermal noise on the reflected signal will be reduced with fully polarimetric observations and larger an tenna apertures

land geophysical parameters retrieval using the interference pattern gnss r technique in the past years the scientific community has placed a special interest in remotely sensing soil moisture and vegetation parameters radiometry and radar techniques have been widely used for years global navigation satellite systems opportunity signals reflected gnss r over the earth s surface are younger but they have already shown their potential to perform these observations this paper presents a gnss r technique based on global positioning system gps measurements that allows the retrieval of several geophysical parameters from land surfaces this technique measures the power of the interference signal between the direct gps signal and the reflected one after scattering over the land so it is called interference pattern technique ipt this paper presents the results obtained after applying the ipt for topography soil moisture and vegetation height retrievals over vegetation covered soils

reconstructing climate change and ombrotrophic bog development during the last 4000 years in northern poland using biotic proxies stable isotopes and trait based approach article i nfo in this study we present a record spanning the last 4000 years from a baltic bog kusowskie bagno in northern poland using numerous biotic and abiotic proxies such as testate amoebae depth to water table reconstruc tions stable carbon isotopes 13 c plant macrofossils proxies for local vegetation and mire surface wetness pollen and spores proxies for regional vegetation and human impact we reconstructed and identified the re gional hydro climatic signal of kusowskie bagno bog and compared it to other bog records around the baltic sea our aims were to 1 combine the species traits of bryophytes and testate amoebae and more common proxies isotopes plant micro and macro remains to infer past peatland development 2 compare the hydro climatic signal of kusowskie bagno bog to existing records around the baltic sea we found that kusowskie bagno bog was very wet during the last 4000 years and even drainage and peat exploitation had not disturbed its hydrology in northern part in the last 200 years carbon isotopes and plant macrofossils were significantly re latedtospecifictraitsoftestateamoebae whichinturnreflectedthewatertablechangesoverthelast4000years kusowskie bagno recorded at least the following wet shifts ad 250 550 850 1250 and 1700 while wet condi tions occurred during the migration period at ca ad 550 furthermore the testate amoeba based quantitative wetness reconstruction in kusowskie bagno bog resembles the pattern observed in other sites around the baltic i e estonia finland ireland northernbritainandthe7500 yearrecordfromthe st zkibog northern poland our results provided statistically validated evidence that interactions between plant and microbe need to be more considered further to reconstruct past hydrological this is the first study of past hydro climatic changes in peatlands based upon a trait based approach

mediterranean balloon experiment ocean wind speed sensing from the stratosphere using gps reflections abstract the mediterranean balloon experiment mebex conducted in august 99 from the middle up stratosphere was designed to assess the wind retrieval sensitivity of global navigation satellite systems reflections gnssr technology from high altitudes global positioning system reflected signals gpsr collected at altitudes around 37 km with a dedicated receiver have been inverted to mean square slopes mss of the sea surface and wind speeds the theoretical tool to interpret the geophysical parameters was a bistatic model which also depends on geometrical parameters the results have been analyzed in terms of internal consistency repeatability and geometry dependent performance in addition wind velocities have been compared to independent measurements by quikscat topex ers ra and a radio sonde with an agreement better than 2 m s a numerical weather prediction model nwpm the mm5 mesoscale forecast model has also been used for comparison with varying results during the experiment the conclusion of this study confirms the capability of high altitude gpsr delay map receivers with low gain antennas to infer surface winds

sea surface state measured using gps reflected signals we discuss an airborne experiment aimed to establish the potential of the paris concept passive reflectometry and interferometry system to retrieve small features in the sea surface topography the date and location were chosen to coincide with a topex poseidon t p overflight the signals of the global positioning system gps reflected off the sea surface are tracked and compared to the directly received ones to compute the relative delays the features detected in the peak tracking are likely caused by topographic and sea roughness variations while very promising these results open the challenge to use additional information to appropriately separate both contributions

paleoceanographic reconstructions of surface ocean conditions in the greenland iceland and norwegian seas through the last 14 ka based on diatoms prior reconstructions of the last glacial maximum and the holocene did not include detailed paleoclimate data from the greenland iceland and norwegian gin seas which cover sensitive areas for oceanographic boundaries sea ice distribution and deep water formation in order to fill this gap we studied nine well dated sediment cores from this area and reconstructed the paleoceanographic conditions of the surface gin seas at 2000 year intervals since 13 400 bp based on the diatom record results show that a n s extending sea ice free corridor had opened along norway already at 13 400 bp indicating a northward flow of a branch of the north atlantic drift possibly caused by a change in the jet stream flow due to the decreased height of the north american ice sheet a major change of climatic conditions occurred over the gin seas as the insolation anomaly reached its maximum around 9000 bp when the sea ice cover and the oceanic fronts retreated to a northwesterly position along greenland and the ocean temperatures rose the first half of the holocene is recorded as the warmest period during the last 13 400 bp in the gin seas the duration of this climatic optimum decreased both toward the north and toward the margins of the area the second half of the holocene is characterized by a cooling trend in step with the decreasing insolation these results support the proposal of imbrie et al 1992 that the gin seas region acts as an initial responder to insolation changes

deposition models for chronological records abstract long term sedimentary sequences provide a wealth of useful information for research into the palaeo environment especially in relation to past climate change shorter records provide similar information in many archaeological contexts however if such records are to be used to provide precise timing of events and more critically the relative timing between different records methods are needed to provide accurate and precise age depth models for these sequences given the imprecision of individual calibrated radiocarbon determinations it is necessary to use the information we have about the deposition process to refine our chronologies and also to provide interpolation between dated levels in any sequence even with layer counted chronologies the uncertainties are sometimes hard to quantify this paper outlines a range of bayesian models for deposition which have been implemented in the computer programme oxcal these models can be used to combine information from the sediments themselves with radiocarbon or other direct dating information such models have the potential to integrate information between different records and provide a coherent chronology on which to base environmental or archaeological research