middle miocene ocean climate transition high resolution oxygen and carbon isotopic records from deep sea drilling project site 588a southwest pacific high resolution stable isotopic records are presented for the epi benthic foraminifer cibicidoides the inferred shallow dwelling planktonic globigerinoides quadrilobatus and the inferred deep dwelling planktonic globoquadrina dehiscens from the middle miocene 16 12 ma of deep sea drilling project site 588a lord howe rise southwest pacific high resolution multiple species oxygen and carbon isotopic data define the timing and character of the well known middle miocene climatic oceanographic transition with a resolution comparable to quaternary records the benthic foraminiferal 18o record is marked by several large fluctuations from 16 to 14 8 ma followed by a series of rapid 50 kyr 18o increases that suggest a new state of the ocean climate system after 14 8 ma the total middle miocene benthic oxygen isotopic increase of 1 2 is largely incorporated in two steps an increase of 0 8 from 14 5 to 14 0 ma and a second increase of 0 7 from 13 45 to 12 45 ma each step is comprised of a series of marked 18o increases indicative of rapid east antarctic ice sheet growth and contemporaneous deepwater cooling a strong covariance of 0 7 between the benthic and deep dwelling planktonic species from 14 5 to 14 0 ma including a rapid increase from 14 1 to 14 05 ma suggests a 0 7 increase in the 18o composition of seawater 18osw because of east antarctic ice sheet growth comparison of the 18o record of gs quadrilobatus suggests that surface waters warmed at this site by 3 c from 14 1 to 13 6 ma carbon isotopic time series for each species generally covary throughout the early to middle miocene interval 16 12 ma confirming that 13c variations in this interval largely represent reservoir changes high resolution 13c data allow improved resolution of the latter five of six 13c maxima within the well known early to middle miocene carbon isotopic excursion the monterey carbon isotopic excursion from 17 0 to 13 5 ma this is useful for global correlation the last of these maxima ends with a 1 decrease centered from 13 9 to 13 7 ma 300 kyr after the 18o increase considered to reflect east antarctic ice growth covariance between benthic 18o and 13c from 16 to 13 8 ma suggests a sensitive relation between global carbon cycling and the ocean climate system prior to 13 8 ma episodic increases in organic carbon burial may have contributed to deep sea benthic 13c maxima and synchronous global cooling the positive relationship ended at 13 8 ma indicative of changing relations between global carbon cycling and the ocean climate system brought on by the increased stability of the east antarctic ice sheet after a major growth phase from 14 5 to 14 0 ma

spaceborne tomography of multi species indian tropical forests abstract synthetic aperture radar sar backscatter is the coherent combination of the scattering from multiple individual scatterers within the radar resolution cell which results into a 2 d radar image tomographic sar tomosar takes advantage of multiple sar acquisitions to provide 3 d vertical structure of the imaged target over forests parameters such as canopy structure canopy density leaf area and phenology contribute to different sar scattering mechanisms along the vertical dimension of the trees tomography has been demonstrated in various earlier works for forest bio physical parameter estimation using airborne data in this research work multi polarimetric space borne tandem x tomograms are examined for the first time over a multi species indian tropical forest multiple tandem x acquisitions are focused using capon beamforming at five polarimetric channels hh hv vv hh vv and hh vv four distinct forest species compartments are selected representing different canopy structure and density the tomograms obtained in different polarizations for these species are analyzed in detail to understand the scattering patterns across different forest species field surveys carried out in several forest locations provide in situ observations of forest height and vertical structure it was observed that canopy gaps and leaf density play a crucial role for x band sar signal penetration through ground for dense canopy species the backscatter contributions are spread through the canopy while in case of sparse canopy species the ground scattering is dominant vertical profiles obtained at surveyed plot locations are plotted in all polarizations and provide a good agreement with field observations further the obtained tomosar backscatter layers have a good correlation with field measured above ground biomass agb the agb is modeled from tomosar with the hh pol tomosar backscatter layer at 27 m canopy height leading to an agb estimation with correlation r 0 76 and rmse of 50 4 t ha

pollen record of the past 60 ka bp in the middle okinawa trough terrestrial provenance and reconstruction of the paleoenvironment abstract core dgks9602 931 cm in length was retrieved from the middle okinawa trough the age model was correlated with the adjacent core dgks9603 li et al 2001 for the upper part and to the standard specmap chronology down to 60 ka bp using marine oxygen isotope control points pollen analysis was carried out and seven pollen zones were identified the results showed that the pollen spectra in mis 3 were very different to mis 2 but comparable with the holocene the saccate pollen principally pinus predominated in most parts of the core except for the interval of the last glacial maximum lgm and the late mis 3 when artemisia and other herbs increased prominently the ratios of p a pinus artemisia and of pb nap pollen with bladders versus non arboreal pollen were used as a proxy for sea level change and for estimating distances from the coastline to the study site the provenance study using a modern analog technique based on the east asian modern pollen database and fossil pollen assemblages revealed that the pollen were derived from diverse source areas during different stages since 60 ka bp the pollen zones equivalent to mis 1 and 3 were characterized by uncertain and disparate areas of provenance and the surrounding continents including eastern mainland china korea and southern japan possibly made equivalent contributions which may be the result of enhanced pollen transport by the northwesterly wind however the lgm represented in core dgks9602 was distinguished by restricted sources from the exposed east china shelf where the vegetation was quite similar with the herb coverage in the present day north china plain the pollen assemblages sensitively reflected the coastline changes marked by transport patterns between fluvial runoff and northwesterly winds plus ocean currents some pollen changes and limits of pollen zones coincided with the timing of heinrich events implying that the rapid climate fluctuations during mis 3 and mis 2 may have partially resulted in the forest changes in eastern asia the pattern of relative abundance of subtropical and total arboreal taxa is consistent with that of 18 o from hulu cave implying monsoonal climatic control over vegetation change the estimated temperature mat by the means of pollen ratios for the lgm was 5 8 c lower than that in the changjiang river mouth today

wavelet isolation of meridionally moving geopotential height perturbations near the subtropics of eastern africa and their relationship with the madden julian oscillation

single and multipolarimetric sar tomography of forested areas a parametric approach in this paper a technique is described for the tomographic characterization of forested areas through multiple synthetic aperture radar sar observations based on either single or multipolarimetric acquisitions this technique is based on the idea of characterizing the fourier spectrum of the multibaseline data as being constituted by two effective scattering centers displaced along the vertical direction plus the associated decorrelation terms as a result sar tomography will be formulated as the problem of detecting the number of scattering centers within the resolution cell estimating the parameters that describe their spatial structure and evaluating the associated backscattered powers parameter estimation is carried out through the covariance matching estimation technique which provides an asymptotically optimal solution the results of an experiment performed on a real p band multibaseline fully polarimetric data set relative to the forested site of remningstorp sweden are reported

rapid flooding of the sunda shelf a late glacial sea level record the increase in sea level from the last glacial maximum has been derived from a siliciclastic system on the tectonically stable sunda shelf in southeast asia the time from 21 to 14 thousand calendar years before the present has been poorly covered in other records the record generally confirms sea level reconstructions from coral reefs the rise of sea level during meltwater pulse 1a was as much as 16 meters within 300 years 14 6 to 14 3 thousand years ago

decorrelation in interferometric radar echoes a radar interferometric technique for topographic mapping of surfaces implemented utilizing a single synthetic aperture radar sar system in a nearly repeating orbit is discussed the authors characterize the various sources contributing to the echo correlation statistics and isolate the term which most closely describes surficial change they then examine the application of this approach to topographic mapping of vegetated surfaces which may be expected to possess varying backscatter over time it is found that there is decorrelation increasing with time but that digital terrain model generation remains feasible the authors present such a map of a forested area in oregon which also includes some nearly unvegetated lava flows such a technique could provide a global digital terrain map

regression analysis of zonally narrow components of the mjo abstractrecent works have demonstrated that eastward propagating features smaller than zonal wavenumber 3 but with spatial structures similar to those of the madden julian oscillation mjo frequently develop over the indo pacific warm pool these signals are characterized by periods shorter than 4 weeks but since they occur as part of a spectral peak of the mjo they might be characterized by similar physics these zonally narrow features occur at any phase of traditionally defined 30 60 day mjo events but they occur most frequently in its active convective phase this work presents a linear regression analysis based on filtering in the wavenumber frequency domain to compare such signals with traditionally defined mjos and 15 30 m s 1 convectively coupled kelvin waves results show that the trough collocated with the easterly wind anomaly extends westward into the region of lower tropospheric westerly wind and deep convection in the zonally narrow slow signals and mjos the fast kelvin waves have a ri

pollen quantitative distribution in marine and fluvial surface sediments from the northern south china sea new insights into pollen transportation and deposition mechanisms in order to improve the understanding of pollen transportation and deposition mechanisms in northern south china sea scs 45 seafloor surface sediment samples from the scs and nine surface sediment samples from the pearl river mouth were analyzed palynologically the spatial distributions of pollen and spore taxa suggest that various transport mechanisms and the production at the source the dominant pollen pinus poaceae cyperaceae and fern spores are most abundant in the river mouth and decrease with increasing distance from the land suggesting they are mainly derived from the pearl river drainage basin and strongly dispersed by river plume and ocean currents which reflects a dominant pollen transportation pattern in the northern scs podoconpus and temperate broad leaved components pollen such as evergreen quercus and castanopsis pollen is common in marine samples and is scattered in the pearl river samples reflecting their extensive source areas and dispersal in more than one route however some pollen types of conifers are mostly deposited close to the shore such as dacrydium picea and abies which are restricted near hainan island and taiwan island excluding evergreen quercus and castanopsis pollen the total tropical and subtropical components poorly reflect their parent plants and fewer such pollen are transported over long distances however the source areas of some other pollen taxa e g phyllociadus artemisia and chenopodiaceae are unclear spatially varying ratios of spores to pollen indicate that spores are relatively easily transported by water over longer distances than are pollen grains this study provides a sound basis for interpreting quaternary pollen deposits from the northern scs and for further evaluation of pollen dispersal and deposition in marine and fluvial deposits c 2013 elsevier ltd and inqua all rights reserved

patterns of vegetation and climate change in the northern south china sea during the last glaciation inferred from marine palynological records abstract high resolution marine palynological records from the northern south china sea scs provide new information concerning the regional history of vegetation and climate conditions during the last glaciation 70 19 cal ka bp the preservation of rich pollen from tropical and subtropical broadleaf trees largely composed of evergreen quercus castanopsis and euphorbiaceae suggests that a southern subtropical climate prevailed during the last glaciation including the period of the last glacial maximum relatively higher percentages of such pollen taxa occurred during marine isotope stage mis 3 when phyllocladus pollen from the south also increased indicating a warmer terrestrial climate and a strengthened east asian summer monsoon comparing to mis 4 and 2 moreover the maximum percentages of such pollen occurred during the early mis 3 implying that an optimal climate prevailed in this period the reconstructed terrestrial climate corresponds well to marine evidence such as 18o values from planktonic foraminifer shell and records of sea surface temperature this study confirmed that the regional terrestrial climate could be linked closely to changes in both global ice volume and the east asian monsoon attributable to variations of the earth s orbital parameters modern palynological investigations and statistical analyses of the pollen percentages in the profiles indicate that pinus pollen and spores are easily transported by water flow in the northern scs therefore their relative abundance peaks suggest that several wet intervals occurred during the last glaciation

marine palynological record for tropical climate variations since the late last glacial maximum in the northern south china sea the upper part 191 1439 cm of the marine sediment core md05 2906 from the northern south china sea scs was palynologically investigated the chronology suggested that it covered the record since 19 calendar kiloyears before present cal ka bp and revealed a detailed environmental change history since the late last glacial maximum lgm during the late lgm due to the lowered sea level 100 m lower and the shortened distance from the shore to the study site the pollen concentration was very high the pollen assemblages were dominated by non arboreal taxa especially artemisia pollen before 15 cal ka bp abundant subtropical and tropical pollen taxa were still important components and a south subtropical climate prevailed during the late lgm the coexistent rich artemisia pollen possibly was not derived from near shores but was derived mainly from the northern exposed continental shelf in the east china sea ecs after 15 cal ka bp with the rise in the sea level and enhanced distance from the pollen source areas to the core site pollen concentrations started to decline gradually however during the late deglaciation and early holocene the higher concentrations of many pollen taxa reoccurred which cannot be attributed to the sea level changes pinus pollen deposited in the core which is considered to be mostly water carried based on many modern pollen surveys also started to dramatically increase at the same time therefore the higher pollen concentration with more pinus and typha an aquatic plant pollen indicated a notably enhanced terrestrial runoff and precipitation during the last deglaciation holocene transition 11 3 9 4 cal ka bp we inferred that a strong summer monsoon occurred at this time during the late lgm deglaciation transition period the pollen assemblage reflected a gradually warming climate and the climate fluctuations derived from the high latitudes were not well identified this study suggests that solar insolation played a crucial role in controlling the east asian monsoon and hydrological cycle in the northern scs

geochemical records of taiwan sourced sediments in the south china sea linked to holocene climate changes we present a multi proxy geochemical analysis of core kng5 retrieved from the northern south china sea slope spanning the last 13 0 ka bp to assess the response of weathering and erosion processes in the southwestern taiwan river basin to climate change a provenance analysis indicates that the core sediments were primarily derived from the southwestern taiwan river and can be used to reconstruct the erosion and or weathering history of this river basin the chemical index of alteration the plagioclase index of alteration rb sr al ti principle component 1 and k al combined with terrigenous mass accumulation rates and the proportion of clay exhibit sharp excursions from 12 0 to 5 5 ka peaking at 10 0 ka which suggests strong chemical weathering and physical erosion during the early mid holocene the period of the maximum summer monsoon abrupt falling weathering trends during 5 2 and 3 5 ka bp correlate with a weaker monsoon after 3 5 ka bp a stable lower weathering trend to the present day was evident indicating the deposition of less weathered sediments in the slope when the monsoon rainfall was weakening a good correlation between our proxy records of chemical weathering and variations of the monsoon intensity in south china emphasizes that variation in monsoon intensity is most likely the primary drive of the intensity of weathering and erosion in southwestern taiwan river sediments over the last 13 0 ka bp finally we concluded that geochemical parameters can be used as reliable proxies for climate variation on a millennial centennial time scale in such areas as taiwan where weathering limited regimes exist c 2015 elsevier b v all rights reserved

a systematic comparison of tropical waves over northern africa part i influence on rainfall abstractlow latitude rainfall variability on the daily to intraseasonal time scale is often related to tropical waves including convectively coupled equatorial waves the madden julian oscillation

three dimensional multipass sar focusing experiments with long term spaceborne data synthetic aperture radar sar interferometry is a modern efficient technique that allows reconstructing the height profile of the observed scene however apart for the presence of critical nonlinear inversion steps particularly crucial in abrupt topography scenarios it does not allow one to separate different scattering mechanisms in the elevation height direction within the ground pixel overlay of scattering at different elevations in the same azimuth range resolution cell can be due either to the penetration of the radiation below the surface or to perspective ambiguities caused by the side looking geometry multibaseline three dimensional 3 d sar focusing allows overcoming such a limitation and has thus raised great interest in the recent research first results with real data have been only obtained in the laboratory and with airborne systems or with limited time span and spatial coverage spaceborne data this work presents a novel approach for the tomographic processing of european remote sensing satellite ers real data for extended scenes and long time span besides facing problems common to the airborne case such as the nonuniformly spaced passes this processing requires tackling additional difficulties specific to the spaceborne case in particular a space varying phase calibration of the data due to atmospheric variations and possible scene deformations occurring for years long temporal spans first results are presented that confirm the capability of ers multipass tomography to resolve multiple targets within the same azimuth range cell and to map the 3 d scattering properties of the illuminated scene

the displacement field of the landers earthquake mapped by radar interferometry geodetic data obtained by ground or space based techniques can be used to infer the distribution of slip on a fault that has ruptured in an earthquake although most geodetic techniques require a surveyed network to be in place before the earthquake1 3 satellite images when collected at regular intervals can capture co seismic displacements without advance knowledge of the earthquake s location synthetic aperture radar sar interferometry first introduced4 in 1974 for topographic mapping5 8 can also be used to detect changes in the ground surface by removing the signal from the topography9 10 here we use sar interferometry to capture the movements produced by the 1992 earthquake in landers california11 we construct an interferogram by combining topographic information with sar images obtained by the ers 1 satellite before and after the earthquake the observed changes in range from the ground surface to the satellite agree well with the slip measured in the field with the displacements measured by surveying and with the results of an elastic dislocation model as a geodetic tool the sar interferogram provides a denser spatial sampling 100 m per pixel than surveying methods1 3 and a better precision 3 cm than previous space imaging techniques12 13

reconstruction of sea surface conditions at middle to high latitudes of the northern hemisphere during the last glacial maximum lgm based on dinoflagellate cyst assemblages abstract a new calibration database of census counts of organic walled dinoflagellate cyst dinocyst assemblages has been developed from the analyses of surface sediment samples collected at middle to high latitudes of the northern hemisphere after standardisation of taxonomy and laboratory procedures the database comprises 940 reference data points from the north atlantic arctic and north pacific oceans and their adjacent seas including the mediterranean sea as well as epicontinental environments such as the estuary and gulf of st lawrence the bering sea and the hudson bay the relative abundance of taxa was analysed to describe the distribution of assemblages the best analogue technique was used for the reconstruction of last glacial maximum lgm sea surface temperature and salinity during summer and winter in addition to sea ice cover extent at sites from the north atlantic n 63 mediterranean sea n 1 and eastern north pacific n 1 three of the north atlantic cores from the continental margin of eastern canada revealed a barren lgm interval probably because of quasi permanent sea ice six other cores from the greenland and norwegian seas were excluded from the compilation because of too sparse assemblages and poor analogue situation at the remaining sites n 54 relatively close modern analogues were found for most lgm samples which allowed reconstructions the new lgm results are consistent with previous reconstructions based on dinocyst data which show much cooler conditions than at present along the continental margins of canada and europe but sharp gradients of increasing temperature offshore the results also suggest low salinity and larger than present contrasts in seasonal temperatures with colder winters and more extensive sea ice cover whereas relatively warm conditions may have prevailed offshore in summer from these data we hypothesise low thermal inertia in a shallow and low density surface water layer

atmospheric effects in interferometric synthetic aperture radar surface deformation and topographic maps interferogram images derived from repeat pass spaceborne synthetic aperture radar systems exhibit artifacts due to the time and space variations of atmospheric water vapor other tropospheric variations such as pressure and temperature also induce distortions but the effects are smaller in magnitude and more evenly distributed throughout the interferogram than the wet troposphere term spatial and temporal changes of 20 in relative humidity lead to 10 cm errors in deformation products and perhaps 100 m of error in derived topographic maps for those pass pairs with unfavorable baseline geometries in wet regions such as hawaii these are by far the dominant errors in the spaceborne imaging radar c and x band synthetic aperature radar sir c x sar interferometric products the unknown time delay from tropospheric distortion is independent of frequency and thus multiwavelength measurements such as those commonly used to correct radar altimeter and global positioning system gps ionospheric biases cannot be used to rectify the error in the topographic case the errors may be mitigated by choosing interferometric pairs with relatively long baselines as the error amplitude is inversely proportional to the perpendicular component of the interferometer baseline for the sir c x sar hawaii data we found that the best longest baseline pair produced a map supporting 100 m contouring whereas the poorest baseline choice yielded an extremely noisy topographic map even at this coarse contour interval in the case of deformation map errors the result is either independent of baseline parameters or else very nearly so here the only solution is averaging of independent interferograms so in order to create accurate deformation products in wet regions many multiple passes may be required rules for designing optimal data acquisition and processing sequences for interferometric analyses in nondesert parts of the world are 1 to use the longest radar wavelengths possible within ionospheric scintillation and faraday rotation limits 2 for topography maximize interferometer baseline within decorrelation limits and 3 for surface deformation use multiple observations and average the derived products following the above recipe yields accuracies of 10 m for digital elevation models and 1 cm for deformation maps even in very wet regions such as hawaii

a wave number frequency wavelet analysis of convectively coupled equatorial waves and the mjo over the indian ocean convectively coupled equatorial waves and the madden julian oscillation mjo constitute the dominant coherent modes of planetary to synoptic scale organized convection in the tropics this work presents a space time wavelet analysis of outgoing longwave radiation olr data globally at wavenumbers 0 1 and isolated more closely about the indian ocean at higher wavenumbers the mean power spectrum shows broad similarity to fourier power spectra in previous works after normalization by a red background the seasonal cycle of the power spectrum is analyzed along with its association with the phases of an index of the mjo and background state zonal winds at a variety of pressure levels over the indian ocean results show substantial variability across the seasonal cycle and the mjo in the distribution of power above the background results also show that the spectral peaks associated with the mjo and kelvin and equatorial rossby waves lose 20 50 of their normal variance during periods of strong easterly wind in the upper troposphere over the indian ocean while at the same time fast westward moving waves increase between wavenumbers 7 and 14 and periods of 2 6 days

amplitude and timing of sea surface temperature change in the northern south china sea dynamic link to the east asian monsoon magnesium calcium mg ca ratios of foraminiferal shells from a sediment core from the northern south china sea a semi enclosed basin in the western tropical pacific document variations in sea surface temperature sst during the past 145 k y glacial ssts were 4 c colder than interglacial ssts during the last deglaciation most of the warming was accomplished in a single abrupt step after continental ice sheet decay had already begun but warming and ice sheet demise were nearly synchronous during the penultimate deglaciation abrupt sst changes of the past 15 k y were apparently synchronous with events in east asian monsoon rainfall suggesting that variations in monsoon winds and their influence on surface circulation of the western pacific exerted a strong control on northern south china sea ssts we suggest that this link persisted for the previous 130 k y during which time orbital scale 2 3 c sst changes and several small 2 c abrupt sst events occurred in the northern south china sea the similar timing of northern south china sea sst on a benthic 1 8 o time scale to a well dated speleothem record from eastern china suggests that the demise of ice sheets associated with the penultimate deglaciation did not precede northern hemisphere summer insolation increase our results suggest that surface waters had higher 1 8 o values during times of strong summer monsoon than during times of weak monsoon likely reflecting a redistribution of 1 8 o depleted rainfall from land during times of strong summer monsoons to the western pacific during times of weaker summer monsoons

multiscale convective wave disturbances in the tropics insights from a two dimensional cloud resolving model abstract multiscale convective wave disturbances with structures broadly resembling observed tropical waves are found to emerge spontaneously in a nonrotating two dimensional cloud model forced by uniform cooling to articulate the dynamics of these waves model outputs are objectively analyzed in a discrete truncated space consisting of three cloud types shallow convective deep convective and stratiform and three dynamical vertical wavelength bands model experiments confirm that diabatic processes in deep convective and stratiform regions are essential to the formation of multiscale convective wave patterns specifically upper level heating together with low level cooling serves to preferentially excite discrete horizontally propagating wave packets with roughly a full wavelength structure in troposphere and dry phase speeds cn in the range 16 18 m s 1 these wave packets enhance the triggering of new deep convective cloud systems via low level destabilization the new convection in turn caus

modeling tropical convergence based on the moist static energy budget abstract the vertically integrated moist static energy equation provides a convenient starting point for the construction of simple models of the time mean low level convergence in the tropics a vertically integrated measure of the moist static stability the gross moist stability proves to be of central importance minima in this quantity mark the positions of the tropical convergence zones we argue that the positions of these minima are determined by the time mean moisture field which is in turn closely tied to the time mean surface temperature

palynological record of climate change during the last deglaciation from the song hong red river delta vietnam abstract the palynological sequence from core nd 1 on the song hong delta in the northern vietnam reveals the climate change during the last deglaciation the identified pollen in the core is dominated by castanopsis lithocarpus elaeocarpus ficus piperaceae and quercus high percentages of temperate taxa including the conifers dacrydium podocarpus pinus cupressaceae txodiaceae and cryptomeria and broad leaved taxa of carpinus alnus juglans carya ulmus fagus ilex castanea quercus which have a mainly upland distribution is possibly associated with a lowering of the montane vegetation boundary on the other hand intensified river influence can also result in an increase in the temperate allochthonous taxa after analyzing the magnitude of river influence on pollen assemblages during the sedimentary environment evolution we extracted the climate information and used this to reconstruct climate change during the last deglaciation a cooler climate during 14 5 10 9 cal kyr bp than at present is indicated by higher percentage of temperate types than at present under a similar river influence on the floodplain the younger dryas cooling event is recognized by widely developed grasslands between 12 9 and 11 6 cal kyr bp adding to the evidences for this period from both terrestrial and marine records in regions influenced by the east asian monsoon two other cooling periods 9 4 9 0 cal kyr bp and 6 5 5 2 cal kyr bp are indicated by increases of temperate pollen taxa such as cryptomeria alnus quercus and castanea

late quaternary upwelling intensity and east asian monsoon forcing in the south china sea foraminifera from two cores off eastern vietnam and the northwestern philippines where modern summer and winter monsoon driven upwelling occurs in the south china sea respectively were analyzed to evaluate the changes in paleoproductivity and upper water structure over the last 220 000 yr we observed enhanced organic carbon flux and a shoaled thermocline when upwelling intensified off eastern vietnam during interglacial ages and off the northwestern philippines during glacial ages this indicates that the east asian summer monsoon increased while the winter monsoon decreased during interglacial ages particularly the upwelling reached a maximum off eastern vietnam during late marine isotopic stage mis 5 and off the northwestern philippines during mis 2 implying that the summer monsoon decreased gradually since mis 5 while the winter monsoon displayed an opposite trend the variations in upwelling proxies exhibit a distinct cyclicity with frequencies near 41 000 yr and 23 000 yr off eastern vietnam in contrast to a strong frequency peak near 100 000 yr off the northwestern philippines we suggest that the east asian summer monsoon has been forced by changes in solar insolation associated with precession and obliquity while ice volume forcing is probably a primary factor in determining the strength and timing of the east asian winter monsoon but with less important insolation forcing

nonlinear subsidence rate estimation using permanent scatterers in differential sar interferometry discrete and temporarily stable natural reflectors or permanent scatterers ps can be identified from long temporal series of interferometric sar images even with baselines larger than the so called critical baseline this subset of image pixels can be exploited successfully for high accuracy differential measurements the authors discuss the use of ps in urban areas like pomona ca showing subsidence and absidence effects a new approach to the estimation of the atmospheric phase contributions and the local displacement field is proposed based on simple statistical assumptions new solutions are presented in order to cope with nonlinear motion of the targets

very high resolution spaceborne sar tomography in urban environment synthetic aperture radar tomography tomosar extends the synthetic aperture principle into the elevation direction for 3 d imaging it uses stacks of several acquisitions from slightly different viewing angles the elevation aperture to reconstruct the reflectivity function along the elevation direction by means of spectral analysis for every azimuth range pixel the new class of meter resolution spaceborne sar systems terrasar x and cosmo skymed offers a tremendous improvement in tomographic reconstruction of urban areas and man made infrastructure the high resolution fits well to the inherent scale of buildings floor height distance of windows etc this paper demonstrates the tomographic potential of these sars and the achievable quality on the basis of terrasar x spotlight data of urban environment a new wiener type regularization to the singular value decomposition method equivalent to a maximum a posteriori estimator for tomosar is introduced and is extended to the differential case 4 d i e space time different model selection schemes for the estimation of the number of scatterers in a resolution cell are compared and proven to be applicable in practice two parametric estimation algorithms of the scatterers elevation and their velocities are evaluated first 3 d and 4 d reconstructions of an entire building complex including its radar reflectivity with very high level of detail from spaceborne sar data by pixelwise tomosar are presented

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

analysis of convectively coupled kelvin waves in the indian ocean mjo abstract the active convective phase of the madden julian oscillation hereafter active mjo comprises enhanced moist deep convection on its own temporal and spatial scales as well as increased variance in convection associated with higher frequency modes synoptic scale cloud superclusters apparently associated with convectively coupled kelvin waves occur within the active convective envelopes of most mjo events these convectively coupled kelvin waves also occur during the suppressed convective phase of the mjo hereafter suppressed mjo this observational study presents an analysis of outgoing longwave radiation and reanalysis data to determine how these waves behave differently as they propagate through the active and suppressed mjo time indices of the mjo and kelvin waves are derived for over the equatorial indian ocean dates of local extrema in these indices are used to composite data to discern how the waves and associated circulations behave on average then further composites are made based o

a climatology of waves in the equatorial region abstract propagating anomalies of moisture and moist deep convection in the tropics are organized into a variety of large scale modes these include but are not limited to the so called intraseasonal oscillations convectively coupled waves similar to those predicted by shallow water theory on the equatorial beta plane and tropical depression type disturbances along with the annual and diurnal cycles these modes act and interact to control much of the variance of tropical convection analyses of 10 yr of outgoing longwave radiation olr and precipitable water pw data are carried out to develop comparative climatologies of these wavelike modes the analysis relaxes the commonly used cross equatorial symmetry constraints which allows study of the portions of the wavelike processes that are asymmetric across the equator mean background states are found for olr and for pw as functions of day of the year examination of anomalies together with the background reveals much about how the waves are affec

on large scale circulations in convecting atmospheres the dominant thinking about the interaction between large scale atmospheric circulations and moist convection holds that convection acts as a heat source for the large scale circulations while the latter supply water vapour to the convection we show that this idea has led to fundamental misconceptions about this interaction and offer an alternative paradigm based on the idea that convection is nearly in statistical equilibrium with its environment according to the alternative paradigm the vertical temperature profile itself rather than the heating is controlled by the convection which ties the temperature directly to the subcloud layer entropy the understanding of large scale circulations in convecting atmospheres can therefore be regarded as a problem of understanding the distribution in space and time of the subcloud layer entropy we show that the subcloud layer entropy is controlled by the sea surface temperature the surface wind speed and the large scale vertical velocity in the convecting layer and demonstrate how the recognition of this control leads to a simple physically consistent view of large scale flows ranging from the hadley and walker circulations to the 30 50 day oscillation in particular we argue that the direct effect of convection on large scale circulations is to reduce by roughly an order of magnitude the effective static stability felt by such circulations and to damp all of them

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

mapping small elevation changes over large areas differential radar interferometry a technique that uses synthetic aperture radar sar images to measure very small 1 cm or less surface motions with good resolution 10 m over large swaths 50 km is presented along with experimental results the method could be used for accurate measurements of many geophysical phenomena including swelling and buckling in fault zones residual displacements from seismic events and prevolcanic swelling the method is based on sar interferometry where two images are made of a scene by simultaneously flying two physically separated antennas then the phases of corresponding pixels are differenced and altitude formation is deduced from some simple computation and image rectification it is also possible to use one antenna flown twice over the same scene then if the second flight exactly duplicates the track of the first an interesting possibility occurs there would be no phase changes between the images at all unless there was a physical change in the scene such as ground swelling that would alter the distance from some resolution element to the antenna since the phase changes all occur at the short carrier wavelength the basic limitation on sensitivity is only the phase noise in the system when the two imaging passes are made from flight tracks that are separated which is the case with the seasat images used here it is no longer possible to distinguish surface changes from the parallax caused by topography however with some additional computation a third image made at some other baseline may be used to remove the topography and leave only the surface changes this method was applied using seasat data to an imaging site in imperial valley california where motion effects were observed that were ascribed to the expansion of water absorbing clays phase change images of this area are shown along with associated ground truth about the presence of water problems with the technique are explored along with a discussion of future experimental possibilities on upcoming sar missions like earth observing system eos earth resources satellite ers 1 sir c and the venus imaging radar magellan

palaeo ecological significance transport and preservation of organic walled dinoflagellate cysts in the somali basin nw arabian sea to date relatively little information is available about factors influencing organic walled cyst production of tropical dinoflagellates and processes influencing the final burial of cysts in bottom sediments such as transport and preservation to extend this information cyst fluxes were documented for three sediment traps from june 1992 to february 1993 at two sites in the somali basin northwestern arabian sea as well as the cyst association of underlying sediments by comparing cyst associations of contemporaneously collected trap samples at different depths at one site information about transport and processes of decay in the water column was obtained neither transport nor decay appears to have any detectable influence on cyst association during cyst settlement through the water column comparing the trap associations with the underlying sediments indicates that downslope transport appears to have influenced the cyst association on a local scale only species selective decay probably related to the presence of oxygen in bottom sediments has influenced the cyst association most pronouncedly at the most offshore site relating variations in the trap associations with environmental conditions of the overlying surface waters indicates that highest production of both filled and empty cysts occurs during the sw monsoon upwelling based on this correlation three groups of species can be distinguished species with highest fluxes during 1 the first half of the sw monsoon june august bitectatodinium spongium echinidinium granulatum echindinium transparantum echinidnium spp cysts of protoperidinium compressum and cysts of protoperidinium subinerme 2 the transition between the sw monsoon and inter monsoon spiniferites mirabilis and spiniferites spp 3 no particular season all other species cyst associations of all trap samples are dominated by cyst of protoperidinium species cysts with highest fluxes during the sw monsoon form about a third of the associations

tomographic formulation of interferometric sar for terrain elevation mapping topographic mapping with spotlight synthetic aperture radar sar using an interferometric technique is studied included is a review of the equations for determination of terrain elevation from the phase difference between a pair of sar images formed from data collected at two differing imaging geometries this paper builds upon the systems analysis of li and goldstein in which image pair decorrelation as a function of the baseline separation between the receiving antennas was first analyzed in this paper correlation and topographic height error variance models are developed based on a sar image model derived from a tomographic image formation perspective the models are general in the sense that they are constructed to analyze the case of single antenna two pass interferometry with arbitrary antenna line of sight and velocity vector directions correlation and height error variance sensitivity to sar system parameters and terrain gradients are studied

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

deep sea pollen from the south china sea pleistocene indicators of east asian monsoon abstract a high resolution pollen record sampling interval averages 820 years has been obtained from odp site 1144 water depth 2037 m northern south china sea the 504 m sequence in composition length covers the last 1 03 million years according to micropaleontological and isotopic stratigraphy the pollen assemblages are characterized by high proportions of pinus and herb pollen and by their frequent alternations based on these alternations 29 pollen zones have been recognized that are closely correlated to the marine oxygen isotope stages mis 1 29 pinus dominant pollen zones correspond to interglacial periods with lighter 18o values while herb marked ones relate to the heavier 18o stages assigned to glacials judging from the pollen data the exposed northern continental shelf of the south china sea during the glacials was covered by grassland and the extensive northern shelf has formed only since mis 6 ca 150 ka probably as a result of tectonic subsidence tree pollen influx values are indicative of winter monsoon which began to intensify 600 ka ago the summer monsoon variations can be approximated by the fern percentage within the total pollen and spore abundance and the result shows high values in general occurring at interglacials with the maxima at mis 15 5e and 1 the relatively high fern percentage with smaller amplitude in variations before 600 ka might suggest more stable humid conditions before the intensification of winter monsoon

convectively coupled equatorial waves 1 convectively coupled equatorial waves ccews control a substantial fraction of tropical rainfall variability their horizontal structures and dispersion characteristics correspond to matsuno s 1966 solutions of the shallow water equations on an equatorial beta plane namely kelvin equatorial rossby mixed rossby gravity and inertio gravity waves because of moist processes the tilted vertical structures of ccews are complex and their scales do not correspond to that expected from the linear theory of dry waves the dynamical structures and cloud morphology of ccews display a large degree of self similarity over a surprisingly wide range of scales with shallow convection at their leading edge followed by deep convection and then stratiform precipitation mirroring that of individual mesoscale convective complexes ccews have broad impacts within the tropics and their simulation in general circulation models is still problematic although progress has been made using simpler models a complete understanding of ccews remains a challenge in tropical meteorology

holocene east asian summer monsoon records in northern china and their inconsistency with chinese stalagmite δ18o records abstract monsoon precipitation over china exhibits large spatial differences it has been found that a significantly enhanced east asian summer monsoon easm is characterized by increased rainfall in northern china and by reduced rainfall in southern china and this relationship occurs on different time scales during the holocene this study presents results from a diverse range of proxy paleoclimatic records from northern china where precipitation variability is traditionally considered as an easm proxy our aim is to evaluate the evolution of the easm during the holocene and to compare it with all of the published stalagmite 18 o records from the asian monsoon region in order to explore the potential mechanism s controlling the chinese stalagmite 18 o we found that the intensity of the easm during the holocene recorded by the traditional easm proxy of moisture or precipitation records from northern china is significantly different from the chinese stalagmite 18 o records the easm maximum occurred during the mid holocene challenging the prevailing view of an early holocene easm maximum mainly inferred from stalagmite 18 o records in eastern china in addition all of the well dated holocene stalagmite 18 o records covering a broad geographical region exhibit a remarkably similar trend of variation and are statistically well correlated on different time scales thus indicating a common signal however in contrast with the clear consistency in the 18 o values in all of the cave records both instrumental and paleoclimatic records exhibit significant spatial variations in rainfall on decadal to centennial time scales over eastern china in addition both paleoclimatic records and modeling results suggest that holocene east asian summer monsoon precipitation reached a maximum at different periods in different regions of china thus the stalagmite 18 o records from the easm region should not be regarded as a reliable indicator of the strength of the east asian summer monsoon furthermore modern observations indicate that the moisture for precipitation in the east asian monsoon region is mainly derived from the indian ocean the moisture transport route from the indian ocean to the east asian monsoon region during the holocene is almost identical to that of modern precipitation therefore the strong correlation of 18 o records in the easm and indian summer monsoon ism regions and the similarity of the pattern of latitudinal changes in 18 o values in stalagmites and in modern meteoric precipitation along the water vapor transport route further suggests that the stalagmite 18 o records from the easm region are essentially a signal of the isotopic composition of precipitation which is determined mainly by changes in the 18 o of atmospheric vapor in the upstream source region over the indian ocean and indian monsoon region via the upstream depletion mechanism finally the main trends of the stalagmite 18 o records are strongly correlated with the known evolution of the ism and therefore these records reflect the history of the ism rather than that of the easm our findings support the conclusion that easm variability is mainly controlled by northern hemisphere summer insolation and was strongly modulated by ice volume during the last deglaciation and early holocene which delayed the response of the easm maximum to peak insolation forcing

imaging the internal structure of an alpine glacier via l band airborne sar tomography in this paper we report results from the analysis of 3 d l band airborne synthetic aperture radar sar acquisitions acquired in march 2014 over the mittelbergferner glacier austrian alps during the european space agency esa campaign alptomosar the campaign included coincident in situ measurements of snow and ice properties and ground penetrating radar gpr data acquired at 600 and 200 mhz over a total length of 18 km radar data were acquired by repeatedly flying an l band sar along an oval racetrack at an altitude of about 1300 m over the glacier such that two data stacks from opposite views are obtained data from all passes were coherently combined to achieve 3 d resolution capabilities resulting in the generation of 3 d tomographic sar tomosar cubes where each voxel represents l band radar reflectivity from a particular location in the 3 d space at a spatial resolution on the order of meters tomosar cubes were finally corrected to account for wave propagation velocity into the ice which was a necessary step to associate the observed features with their geometrical location hence enabling a direct comparison to gpr data the tomosar cubes show the complexity of the glacier subsurface scattering most areas are characterized by surface scattering in proximity of the ice surface plus a complex pattern of in depth volumetric scattering beneath and scattering at the ice bedrock interface various subsurface features observed in gpr transects at 200 mhz clearly showed up in tomosar sections as well particularly firn bodies crevasses layer transitions and bedrock reflection down to 50 m below the ice surface

plio quaternary sedimentation processes and neotectonics of the northern continental margin of the south china sea abstract analyses of over 6600 km of reflection seismic profiles on the northern continental margin of the south china sea permit the recognition of four quaternary high frequency type 1 sequences of the 4th order deposited during the past ca 690 kyr at the present day shelf edge only lowstand systems tracts characterised by a prograding clinoformal internal reflection pattern are preserved the prograding complexes can be considered as regressive units accumulated during relative sea level falls they exhibit internal discontinuities which might point to minor sea level fluctuations of the 5th order a preliminary regional relative sea level curve for the past 630 kyr is established using the present positions of the delta fronts mapped the neotectonics curve derived by subtracting eustatic sea level changes from the relative sea level curve shows that the depths of the delta fronts today are controlled primarily by regional tectonic movements and the global sea level our seismo stratigraphic interpretation documents that the area off hong kong and around the dongsha islands experienced two uplift episodes during the past 5 ma namely at the miocene pliocene boundary and at the end of the lower middle pleistocene respectively these uplift events which are centred on the dongsha rise led to its subaerial exposure and to the erosion of the pliocene and most of the pleistocene strata the change from thermal subsidence of the continental margin initiated at the end of the drift phase to the phase of magmato tectonic uplift was caused by a reorientation of the tectonic regime the recent depositional environment on the northern continental margin of the south china sea is dominated by sediment accumulation within the inner shelf and the zhujiang pearl river estuary the outer shelf and upper slope especially around the dongsha islands are characterised by bypass of terrigenous material the sedimentary column in the deepsea basin has a thickness of more than 2 km and comprises 14 depositional units starting with terrestrial rift deposits it overlies oceanic as well as transitional crust

first demonstration of airborne sar tomography using multibaseline l band data in synthetic aperture radar sar interferometry the phase differences between two different sensor positions are used to estimate the terrain topography although it is possible in this way to find a three dimensional 3d surface representation the distribution of the different scatterers in the height direction at a fixed range and azimuth position remains unknown contrary to this tomographic techniques enable a real geometric resolution capability in the height direction and introduce new possibilities for many applications and inversion problems even misinterpretations in sar images caused by layover and foreshortening effects can be solved by the tomographic processing in this paper the successful experimental realization of polarimetric airborne sar tomography is demonstrated for the first time the authors present the concept of aperture synthesis for tomographic imaging for the case of a multibaseline imaging geometry and discuss the constraints arising from the limited number of flight tracks they propose a method for reduction of the height ambiguities associated to the irregular and undersampled spatial distribution of the imaging positions finally they address the experimental requirements for polarimetric airborne sar tomography and show experimental results using a multibaseline data set acquired in l band by dlr s experimental sar e sar of a test site near oberpfaffenhofen germany

actively growing anticlines beneath catania from the distal motion of mount etna s decollement measured by sar interferometry and gps we used sar interferometry and gps to measure the rise of an anticline beneath the urban area of catania italy which originates from outward thrusting above the basal decollement of etna volcano the anticline grows at a rate of over 0 015 m a 1 of se thrusting and about 0 007 m a 1 of relative uplift by relating this growth to the simultaneous extension measured at the summit of the volcano we demonstrate the occurrence of active volcanic spreading this process may exert a control on eruptions earthquakes sector collapses and landslides

a high resolution absolute dated holocene and deglacial asian monsoon record from dongge cave china abstract we present a continuous record of the asian monsoon over the last 16 ka from 18o measurements of stalagmite calcite over 900 oxygen isotopic measurements providing information on shifts in monsoon precipitation are combined with a chronology from 45 precise 230th dates 18o and therefore asian monsoon intensity generally follows changes in insolation although changes in 18o are generally accommodated in abrupt shifts in contrast to smoothly varying insolation indicating that threshold effects may be important 18o decreased dramatically 3 at the start of the holocene 11 5 ka and remained low for 6 ka four positive 18o events centered at 11225 97 yr bp 1 05 10880 117 yr bp 1 15 9165 75 yr bp 1 4 and a double event centered at 8260 64 yr bp 1 1 and 8080 74 yr bp 1 0 punctuated this period of high monsoon intensity all four events correlate within error with climate changes in greenland ice cores thus the relationship between the asian monsoon and the north atlantic observed during the glacial period appears to continue into the early holocene in addition three of the four events correlate within error with outburst events from lake agassiz the decline of monsoon intensity in the mid late holocene is characterized by an abrupt positive shift in 18o which occurs at 3550 59 yr bp 1 1 in 100 yr in addition the holocene is punctuated by numerous centennial and multi decadal scale events amplitudes 0 5 to 1 up to half the amplitude of the glacial interstadial events seen in the last glacial period thus holocene centennial and multi decadal scale monsoon variability is significant although not as large as glacial millennial scale variability the monsoon shows a strong connection with northern south american hydrological changes related by changes in itcz position spectral analysis of the 18o record shows significant peaks at solar periodicities of 208 yr and 86 yr suggesting variation is influenced by solar forcing however there are numerous other significant peaks including peaks at el nino frequencies observed for high resolution portions of the record between 8110 and 8250 yr which suggest that changes in oceanic and atmospheric circulation patterns in addition to those forced by solar changes are important in controlling holocene monsoon climate in addition for this high resolution portion we observe a distinctive biennial oscillation of the asian monsoon which has been associated with the tropospheric biennial oscillation tbo

influence of the basic state zonal flow on convectively coupled equatorial waves observational data are used to test the hypothesis that the basic state modulates the dispersion properties of convectively coupled equatorial waves ccews this hypothesis is based on shallow water theory which predicts that the zonal speed of propagation of such tropospheric equatorial modes is altered by the equivalent depth and the basic zonal flow localized space time spectra are calculated to investigate how ccew spectral peaks vary across the tropics and how they are affected by the variations in zonal wind observed geographically and by season doppler shifting by the basic state barotropic zonal flow is readily identified once this doppler shifting is taken into account the equivalent depths of ccews inferred from global power spectra are surprisingly uniform both geographically and temporally however there are also detectable modulations that appear consistent with changes in vertical shear of the zonal flow along with other shifts that are not as easily explained

source and distribution of pollen in the surface sediment of daihai lake inner mongolia daihai lake lies in the transitional area from semi humid to semi arid region and also in the north margin of the east asia monsoon the analysis of 65 pollen samples from the surface sediment of daihai lake and alluvium of its inflow rivers revealed the characteristics of pollen distribution and different transport vectors most pollen grains in daihai lake come from its inflow rivers although rain out and wind are also important activities of insects birds and humans may also carry pollen into the lake the pollen assemblages are consistent with the regional vegetation in general the variance of pollen assemblages in different parts of the lake reflects changes of local vegetation near the lakeshore pollen concentrations in the lake sediment surface are lower than that in fresh alluvium in its inflow rivers and the highest percentages and concentrations of major pollen types mainly appear in the margin part of the lake dca demonstrated that there are more similarities between lake sediments and the inflow rivers than there are differences

demonstration of super resolution for tomographic sar imaging in urban environment tomographic synthetic aperture radar sar inversion including sar tomography and differential sar tomography is essentially a spectral analysis problem the resolution in the elevation direction depends on the elevation aperture size i e on the spread of orbit tracks since the orbits of modern meter resolution spaceborne sar systems such as terrasar x are tightly controlled the tomographic elevation resolution is at least an order of magnitude lower than in range and azimuth hence super resolution sr reconstruction algorithms are desired considering the sparsity of the signal in elevation a compressive sensing based super resolving algorithm named scale down by l1 norm minimization model selection and estimation reconstruction sl1mmer pronounced slimmer was proposed by the authors in a previous paper the ultimate bounds of the technique on localization accuracy and sr power were investigated in this paper the essential role of sr for layover separation in urban infrastructure monitoring is indicated by geometric and statistical analysis it is shown that double scatterers with small elevation distances are more frequent than those with large elevation distances furthermore the sr capability of sl1mmer is demonstrated using terrasar x real data examples for a high rise building complex the percentage of detected double scatterers is almost doubled compared to classical linear estimators among them half of the detected double scatterer pairs have elevation distances smaller than the rayleigh elevation resolution this confirms the importance of sr for this type of applications

intertropical convergence zones during the active season in daily data synoptic scale variability of vorticity structures in the lower troposphere of the tropics is analyzed in 23 yr of daily averaged high resolution reanalysis data the vorticity structures can be divided into zonally elongated vorticity strips classified as intertropical convergence zones itczs and more localized maxima termed westward propagating disturbances a composite of such variability is presented for the east to central pacific and for the east atlantic africa region both in summer the composite in the east pacific is zonally elongated and itcz like propagating westward over a number of days before dissipating the spatial structure of the vorticity strip shows the characteristic cyclonic tilt into the latitudinal direction with time that is also seen in modeling experiments the composite over the atlantic africa region shows two active regions that are correlated on synoptic time scales the disturbances in the southern region are better developed and longer lasting even though the time and space scales are smaller than over the east pacific overall variability over the atlantic is consistent with variability due to african easterly waves the double itcz in spring in the east pacific is different from the few earlier studies available it is stronger south of the equator and located at 10 s which is farther poleward than earlier studies have indicated the northern branch that is weak in comparison is located at 5 n the two branches of the double itcz tend to appear in tandem on the 2 week time scale

foraminiferal isotopic evidence for monsoonal activity in the south china sea a present lgm comparison abstract the relationship between planktonic and benthic foraminiferal stable isotope values and oceanographic conditions and factors controlling isotopic variations are discussed on the basis of oxygen and carbon isotopic analyses of 192 modern surface and last glacial maximum lgm samples from the south china sea scs the harmonic variation of benthic 18o in surface sediments with water depth and temperature implies that the temperature is the main factor influencing benthic 18o variations planktonic 18o fluctuates with sea surface temperature sst and salinity sss the n s temperature gradient results in planktonic 18o decreasing from the northeast to the south cool saline waters driven by the winter monsoon are interpreted to have been responsible for the high 18o values in the northeast scs the east asian monsoons not only bring nutrients into the south china sea and maintain high nutrient concentration levels at the southwestern and northeastern ends which cause depleted 13c both in planktonic surface and benthic bottom samples but also reduce planktonic benthic 18o differences the distribution of 18o and 13c in the surface and lgm samples are strikingly similar indicating that the impact of sst and sss has been maintained and nutrient inputs mainly from the northeastern and southwestern ends have been controlled by monsoons since the lgm comparisons of the modern and lgm 18o indicate a difference of about 3 6 c in bottom water temperature and a large surface to bottom temperature gradient during the lgm as compared to today

tomographic sar inversion by l_ 1 norm regularization the compressive sensing approach synthetic aperture radar sar tomography tomosar extends the synthetic aperture principle into the elevation direction for 3 d imaging the resolution in the elevation direction depends on the size of the elevation aperture i e on the spread of orbit tracks since the orbits of modern meter resolution spaceborne sar systems like terrasar x are tightly controlled the tomographic elevation resolution is at least an order of magnitude lower than in range and azimuth hence super resolution reconstruction algorithms are desired the high anisotropy of the 3 d tomographic resolution element renders the signals sparse in the elevation direction only a few pointlike reflections are expected per azimuth range cell this property suggests using compressive sensing cs methods for tomographic reconstruction this paper presents the theory of 4 d differential i e space time cs tomosar and compares it with parametric nonlinear least squares and nonparametric singular value decomposition reconstruction methods super resolution properties and point localization accuracies are demonstrated using simulations and real data a cs reconstruction of a building complex from terrasar x spotlight data is presented

the spectrum of convectively coupled kelvin waves and the madden julian oscillation in regions of low level easterly and westerly background flow abstractthe zonal wavenumber frequency power spectrum of outgoing longwave radiation in the global tropics suggests that power in convectively coupled kelvin waves and the madden julian oscillation mjo is organized into two distinct spectral peaks with a minimum in power in between this work demonstrates that integration of wavelet power in the wavenumber frequency domain over geographical regions of moderate trade winds yields a similar pronounced spectral gap between these peaks in contrast integration over regions of background low level westerly wind yields a continuum of power with no gap between the mjo and kelvin bands results further show that signals in tropical convection are redder in frequency in these low level westerly wind zones confirming that kelvin waves tend to propagate more slowly eastward over the warm pool than other parts of the world results are consistent with the perspective that portions of disturbances labeled as kelvin waves and the mjo that are proximate to kelvin wa

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

holocene evolution of the song hong red river delta system northern vietnam abstract the song hong red river delta located on the western coast of the gulf of bac bo tonkin in the south china sea formed as a result of the song hong sediment discharge throughout the holocene the river s sedimentary basin upstream from the delta plain is not large the delta plain comprises emerged tidal mangrove flats formed during the sea level highstand at 2 3 m 6 4 cal kyr bp and a beach ridge strandplain with straight to lobate beach ridges on the landward and seaward sides of the delta plain respectively the delta affords us the opportunity to examine river mouth morphodynamics comprehensively in relation to sediment discharge and sea level changes in this paper we describe the holocene evolution of the song hong delta system and the river mouth morphodynamics on the basis of seven sediment cores each 30 70 m long taken from the delta plain during 1999 2001 and 101 radiocarbon dates obtained from the core sediments sediments from the seven cores consisting of incised valley fills since the last glacial maximum can be divided in ascending order into fluvial sediments composed of gravelly sand and mottled clay tide influenced estuarine sediments containing shell and wood fragments and deltaic sediments composed of tide influenced sand and mud deposits in which the contents of sand and wood fragments increase upward by applying sequence stratigraphic concepts a transgressive surface can be identified at the gravelly sand mottled clay boundary and the maximum flooding surface can be identified at the estuarine deltaic sediments boundary the lowstand systems tract transgressive systems tract and highstand systems tract record 15 15 9 and 9 0 cal kyr bp respectively during the past 9 kyr the majority of the sediment discharged by the song hong accumulated in the incised valley and enhanced progradation at the river mouth the river mouth prograded from the bay head toward the gulf and its morphology changed from funnel shaped 9 6 cal kyr bp to straight 6 2 cal kyr bp and finally to lobate 2 0 cal kyr bp the morphological change from a funnel shaped to straight coast is interpreted to have been closely related to a hydrologic regime shift from a tide dominated bay head setting to a wave influenced open coast setting the cessation of the sea level rise at 6 cal kyr bp may have played only a small role in the change of river mouth morphology because the progradation rate decelerated from 22 to 4 m yr instead of accelerating at that time the river mouth morphodynamic change from straight to lobate was largely caused by an increase in the song hong sediment discharge from 17 27 9 2 cal kyr bp to 49 million t yr 2 0 cal kyr bp as a result of anthropogenic deforestation along the upper reaches of the song hong