solar radiation maintained glacier recession on kilimanjaro drawn from combined ice radiation geometry modeling 1 in the context of investigating modern glacier recession on kilimanjaro which began around 1880 this study addresses the glacier regime of the vertical ice walls that typically form the margins of kilimanjaro s summit glaciers these walls have suffered a continuous lateral retreat during the twentieth century to evaluate the role of solar radiation in maintaining glacier recession on kilimanjaro a radiation model is applied to an idealized representation of the 1880 ice cap the combined process based model calculates the spatial extent and geometry of the ice cap for various points in time after 1880 support for input data and fundamental assumptions are provided by an automatic weather station that has operated on the summit s northern icefield since february 2000 even in a simple climatic scenario only forced with an annual cycle of clouds the basic evolution in spatial distribution of ice bodies on the summit is modeled well the northern and southern icefields form in characteristic east west orientation which verifies the basic idea behind the model forcing the model with further climate related phenomena improves the results it then additionally reproduces the eastern icefield the third big ice entity on the summit this study qualitatively demonstrates that solar radiation is the main climatic parameter maintaining modern glacier recession on kilimanjaro summit but also suggests that retreat on the inner ice cap margin might have been supported by a secondary energy source the need for additional field measurements is emphasized in order to better understand the complex processes of glacier climate interaction on kilimanjaro index terms 1620 global change climate dynamics 3309 1827 hydrology glaciology 1863 3309 meteorology and atmospheric dynamics climatology 1620 3359 meteorology and atmospheric dynamics radiative processes 9305 information related to geographic region africa keywords tropical glaciers kilimanjaro climate change glacier retreat solar radiation modeling

lateral eddy mixing in the subtropical salinity maxima of the global ocean abstracta suite of observationally driven model experiments is used to investigate the contribution of near surface lateral eddy mixing to the subtropical surface salinity maxima in the global ocean surface fields of salinity are treated as a passive tracer and stirred by surface velocities derived from altimetry leading to irreversible water mass transformation in the absence of surface forcing and vertical processes the transformation rate can be directly related to the integrated diffusion across tracer contours which is determined by the observed velocities the destruction rates of the salinity maxima by lateral mixing can be compared to the production rates by surface forcing which act to strengthen the maxima the ratio of destruction by eddy mixing in the surface layer versus the surface forcing exhibits regional differences in the mean from 10 in the south pacific to up to 25 in the south indian furthermore the regional basins show seasonal and interannual variability in eddy mixing th

measurements of turbulence transfer in the near surface layer over the antarctic sea ice surface from april through november in 2016 the surface energy budget over the antarctic sea ice from 8 april 2016 through 26 november 2016 are presented from april to october sensible heat flux sh and subsurface conductive heat flux g were the heat source of surface while latent heat flux le and net radiation flux rn were the heat sink of surface our results showed larger downward sh due to the warmer air in our site and upward le due to the drier air and higher wind speed in our site compared with sheba data however the values of sh in n ice2015 campaign which located at a zone with stronger winds and more advection of heat in the arctic were comparable to our results under clear skies the values of aerodynamic roughness length z0m and scalar roughness length for temperature z0h being 1 9 10 3 m and 3 7 10 5 m were suggested in this study it is found that snow melting might increase z0m our results also indicate that the value of log z0h z0m was related to the stability of stratification in addition several representative parameterization schemes for z0h have been tested and a couple of schemes were found to make a better performance

comparative precambrian stratigraphy and structure along the mid continent rift the mid continent rift is a geophysically identified tectonic structure that has been traced from kansas northeastward into the lake superior district a related arm has been identified by gravity as extending from eastern lake superior southeastward into the lower peninsula of michigan this rift is of precambrian keweenawan age and began developing approximately 1 1 b y b p for most of its extent this continental class rift system is buried below phanerozoic strata outcrops are found only in east central minnesota northwestern wisconsin and the upper peninsula of michigan the most accepted tectonic model of the mid continent rift is that of a central horst partly covered by clastic rocks bounded by high angle faulting and flanked by basins filled with clastic rocks this model was developed in conjunction with field studies in the southwestern lake superior area and generally has been adopted for minnesota iowa nebraska and kansas a comparable model has yet to be presented for the related arm extending into southern michigan in the lake superior outcrop belt the oldest recognized rifted rocks are layered basalts of middle keweenawan age overlying these basalts is an upper keweenawan thick sedimentary sequence composed of the oronto older and bayfield younger groups these sedimentary rocks are almost entirely clastic with texture ranging from conglomerate to shale mudstone rock colors are principally reds and browns with secondary shades of green and white the oronto group is more immature mineralogically and texturally and more complex structurally than the bayfield group the oronto group also is differentiated by one of its units the nonesuch formation which contains organic shales that bleed liquid hydrocarbons from subsurface fractures and vugs in a michigan copper mine conditions of eposition for both groups are closely allied with an aquatic continental environment specific paleogeography ranged from alluvial fan and plain to deltaic flood plain fluvial and lacustrine southwest and southeast of the lake superior outcrop belt stratigraphic relationships are known principally from fewer than a dozen significant wells drilled into the precambrian within the mid continent rift trend analysis of the proposed upper keweenawan red clastic sedimentary rock column within these wells suggests that the lake superior stratigraphy can be provisionally correlated throughout the mid continent rift trend

glacier recession on kilimanjaro east africa 1912 89 the varying ice extent on the kibo cone of kilimanjaro east africa this century was reconstructed from terrestrial photogrammetric mappings in 1912 and 1953 and satellite images in 1976 and 1989 these were all conformed to the official 1 50 000 topographic sheet the ice distribution on kibo is characterized by lower ice margins on the southern than on the northern flanks and deepest reaching glaciers to the west contrasting with least ice cover on the eastern crater rim the meridional contrast appears to be related to the more abundant precipitation on the southern side the even more striking zonal asymmetry in ice cover is favored by the vigorous diurnal circulations with enhanced afternoon cloudiness blocking insolation on the western slopes the total ice cover diminished from 12 058 to 6675 to 4171 to 3305 x 10 3 m 2 between the years 1912 1953 1976 and 1989 and the three large coherent ice bodies disintegrated into numerous smaller ice fragments

enhancement of mesoscale eddy stirring at steering levels in the southern ocean abstract meridional cross sections of effective diffusivity in the southern ocean are presented and discussed the effective diffusivity keff characterizes the rate at which mesoscale eddies stir properties on interior isopycnal surfaces and laterally at the sea surface the distributions are obtained by monitoring the rate at which eddies stir an idealized tracer whose initial distribution varies monotonically across the antarctic circumpolar current acc in the absence of observed maps of eddying currents in the interior ocean the advecting velocity field is taken from an eddy permitting state estimate of the southern ocean sose a three dimensional advection diffusion equation is solved and the diffusivity diagnosed by applying the nakamura technique on both horizontal and isopycnal surfaces the resulting meridional sections of keff reveal intensified isopycnal eddy stirring reaching values of 2000 m2 s 1 in a layer deep beneath the acc but rising toward the surface on the equatorward flank

mass balance model parameter transferability on a tropical glacier we explore the small scale spatial and temporal transferability of model parameters between two points in the ablation zone of tropical glaciar shallap cordillera blanca peru 9 s 77 w 4800 m a s l in order to provide a robust assessment of the performance of a process based glacier mass balance model relative surface height change is calculated at hourly time steps and cumulative values are compared to surface height measurements made at irregular intervals 14 64 days over the course of two continuous hydrological years august 2006 august 2008 best performing parameter combinations were determined for each point from the outcome of 1000 model simulations for which parameters were varied randomly within a defined range with these parameter combinations measurements for a specific location and time span are well reproduced transferring the parameter combination as optimized for one location to the other location in the ablation zone increases the errors of modeled cumulative mass balance by 5 1326 mm ice eq a 1 transferring the parameter combinations as optimized for one year to the other year increases the modeled errors in cumulative mass balance by 18 3179 mm ice eq a 1 model errors generally increase during periods with frequent snowfall and snow cover this could reflect either the inherent difficulty of modeling complex snow processes or the inability of the model to correctly capture the pattern of albedo evolution at this site the magnitude of errors associated with parameter transfer in space and time highlights the need for improving model performance for robust climatological and or hydrological analyses on tropical glaciers

coherent mesoscale eddies in the north atlantic subtropical gyre 3 d structure and transport with application to the salinity maximum the mean vertical structure and transport properties of mesoscale eddies are investigated in the north atlantic subtropical gyre by combining historical records of argo temperature salinity profiles and satellite sea level anomaly data in the framework of the eddy tracking technique the study area is characterized by a low eddy kinetic energy and sea surface salinity maximum although eddies have a relatively weak signal at surface amplitudes around 3 7 cm the eddy composites reveal a clear deep signal that penetrates down to at least 1200 m depth the analysis also reveals that the vertical structure of the eddy composites is strongly affected by the background stratification the horizontal patterns of temperature salinity anomalies can be reconstructed by a linear combination of a monopole related to the elevation depression of the isopycnals in the eddy core and a dipole associated with the horizontal advection of the background gradient by the eddy rotation a common feature of all the eddy composites reconstructed is the phase coherence between the eddy temperature salinity and velocity anomalies in the upper 300 m layer resulting in the transient eddy transports of heat and salt as an application a box model of the near surface layer is used to estimate the role of mesoscale eddies in maintaining a quasi steady state distribution of salinity in the north atlantic subtropical salinity maximum the results show that mesoscale eddies are able to provide between 4 and 21 of the salt flux out of the area required to compensate for the local excess of evaporation over precipitation

solar radiation cloudiness and longwave radiation over low latitude glaciers implications for mass balance modelling broadband radiation schemes parameterizations are commonly used tools in glacier mass balance modelling but their performance at high altitude in the tropics has not been evaluated in detail here we take advantage of a high quality 2 year record of global radiation g and incoming longwave radiation l measured on kersten glacier kilimanjaro east africa at 5873 m a s l to optimize parameterizations of g and l we show that the two radiation terms can be related by an effective cloud cover fraction neff s og or l can be modelled based on neff derived from measured l or g respectively at neff 1 g is reduced to 35 of clear sky g and l increases by 45 65 depending on altitude relative to clear sky l validation for a 1 year dataset of g and l obtained at 4850 m on glaciar artesonraju peruvian andes yields a satisfactory performance of the radiation scheme whether this performance is acceptable for mass balance studies of tropical glaciers is explored by applying the data from glaciar artesonraju to a physically based mass balance model which requires among others g and l as forcing variables uncertainties in modelled mass balance introduced by the radiation parameterizations do not exceed those that can be caused by errors in the radiation measurements hence this paper provides a tool for inclusion in spatially distributed mass balance modelling of tropical glaciers and or extension of radiation data when only g or l is measured

geographical variability of the first baroclinic rossby radius of deformation global 1 83 18 climatologies of the first baroclinic gravity wave phase speed c1 and the rossby radius of deformation l1 are computed from climatological average temperature and salinity profiles these new atlases are compared with previously published 5 83 58 coarse resolution maps of l1 for the northern hemisphere and the south atlantic and with a 1 83 18 fine resolution map of c1 for the tropical pacific it is concluded that the methods used in these earlier estimates yield values that are biased systematically low by 5 15 owing to seemingly minor computational errors geographical variations in the new high resolution maps of c1 and l1 are discussed in terms of a wkb approximation that elucidates the effects of earth rotation stratification and water depth on these quantities it is shown that the effects of temporal variations of the stratification can be neglected in the estimation of c1 and l1 at any particular location in the world ocean this is rationalized from consideration of the wkb approximation

surface roughness and bulk heat transfer on a glacier comparison with eddy correlation more than 100 simultaneously measured profiles of wind speed and temperature were analyzed to determine the aerodynamic and thermal roughness lengths of glacier ice the results proved to be extremely sensitive to measurement height which is difficult to define precisely on the hummocky terrain of a glacier therefore aerodynamic roughness lengths were estimated from the microtopography of the surface yielding 2 46 mm for ice and 5 5 mm for snow despite the indeterminate nature of the profile analysis it did support the view that the thermal roughness length must decrease as the roughness reynolds number increases a relationship which has been modelled in the literature good agreement between bulk transfer estimates and eddy correlation measurements of fhe sensible heat flux density on melting ice and snow was obtained by combining the aerodynamic roughness length with a suitable model for thermal roughness length

constraining turbulent heat flux parameterization over a temperate maritime glacier in new zealand the turbulent sensible and latent heat fluxes are important components of the surface energy balance over glaciers in the southern alps of new zealand contributing over half the energy available for ablation during large melt events to calculate these terms confidently in glacier mass balance models it is essential to use appropriate parameterizations for surface roughness and atmospheric stability eddy covariance measurements at brewster glacier were obtained over an ice surface to help facilitate an assessment of the calculation of the turbulent heat fluxes the roughness length for momentum was found to be 3 6 x 10 3 m while the roughness lengths for temperature and humidity were two orders of magnitude smaller in agreement with surface renewal theory a monte carlo approach was used to assess the uncertainty in turbulent heat fluxes calculated using the bulk aerodynamic method it was found that input data and roughness length uncertainty could not explain underestimates of observed sensible heat fluxes during periods with low wind speed and large temperature gradients during these periods a katabatic wind speed maximum alters the formulation of the turbulent exchange coefficient to that typically observed in a neutral atmosphere and this has implications for glacier mass balance sensitivity

global surface eddy diffusivities derived from satellite altimetry 1 velocities derived from aviso sea surface height observations adjusted to be nondivergent are used to simulate the evolution of passive tracers at the ocean surface eddy mixing rates are derived from the tracer fields in two ways first the method of nakamura is applied to a sector in the east pacific second the osborn cox diffusivity is calculated globally to yield estimates of diffusivity in two dimensions the results from the east pacific show weak meridional mixing at the surface in the southern ocean 1000 m2 s 1 consistent with previous results but higher mixing rates 3000 5000 m2 s 1 in the tropical ocean the osborn cox diagnostic provides a global picture of mixing rates and agrees reasonably well with the results from the east pacific it also shows extremely high mixing rates 104 m2 s 1 in western boundary current regions the osborn cox diffusivity is sensitive to the tracer initialization which we attribute to the presence of anisotropic mixing processes the mixing rates are strongly influenced by the presence of a mean flow nearly everywhere as shown by comparison with an eddy only calculation with the mean flow absent finally results are compared with other recent estimates of mixing rates using lagrangian and inverse methods

the north atlantic subtropical surface salinity maximum as observed by aquarius aquarius satellite derived sea surface salinity sss data from august 2011 through september 2013 reveals significant seasonal migration and freshening of the subtropical surface salinity maximum sss max area in the north atlantic in good agreement with in situ observations including those obtained as part of the spurs salinity processes in the upper ocean regional study field experiment in 2012 2013 the sss max fluctuated in surface area as defined by the 37 4 surface isohaline during the course of the aquarius time series by about 67 the sss max has a surprisingly large amount of non seasonal variability including a general decrease in salinity throughout the eastern subtropical north atlantic between 2011 2012 and 2012 2013 of about 0 1 0 2 the documented seasonal variability is weakest in the maximum salinity area and increases toward the north and south respectively this is consistent with the important role played by ekman transport and regional excess of evaporation over precipitation in the formation of the sss max

deglaciated areas of kilimanjaro as a source of volcanic trace elements deposited on the ice cap during the late holocene abstract ice fields on kilimanjaro 5895 m a s l tanzania are retreating and 85 of the ice cover has been lost since 1912 the degree to which this recession is exceptional during the holocene is uncertain as age control of the entire ice stratigraphy exists only for the very shallow and very bottom ice of the northern ice field this empirical evidence suggests that the kilimanjaro ice cover may be a persistent holocene feature while a model based on maximum possible extent and a constant shrinkage rate of the summit glaciers suggests a cyclic decay time on the order of one to two centuries today the mass balance of these ice fields is negative and no persistent ice accumulation zones are observed over multiannual scales the expanding deglaciated area within the kilimanjaro caldera should act as an increasingly larger and productive source of volcanic origin aeolian dust that is quickly deposited onto the surface of the adjacent ice fields particularly in the seasonal absence of caldera snow cover variations in the local dust influx may directly influence albedo and the energy balance of these ice fields investigating the characteristics of insoluble material entrapped in the ice remnants of kilimanjaro can thus provide insights into the extent of ice and or continuity of the summit snow cover through time here we report the trace element composition linked to the insoluble particles entrapped in holocene kilimanjaro ice in the context of the current understanding of the past ice accumulation processes including solid precipitations and ablation contributing to build the horizontal caldera ice fields for this purpose we analysed an ice core drilled to bedrock from the northern ice field thought to span the late holocene 2200 bc 1950 ad the ultra low trace element concentrations recorded in this kilimanjaro core are consistent with a generally low volcanic dust source availability i e limited exposure of the deglaciated area in the caldera and fairly continuous ice accumulation during the late holocene in contrast the maximum concentrations for most of the trace elements recorded in the surface ice section suggest that the current lack of ice accumulation on the kilimanjaro ice fields is unusual over the last 4 ka

a possible southeastern extension of the midcontinent rift system located in ohio in 1988 a stratigraphic test core drilled in southwestern ohio penetrated a previously unknown structure and sedimentologic unit core analyses disclosed a sequence of lithic arenite and siltstone of probable pre phanerozoic age deposited within an alluvial fluvial environment a seismic reflection profile across the core site shows a sequence of strong horizontal paleozoic reflectors unconformably overlying eastward dipping layered units of poor reflectivity beyond the core hole total depth a regime of excellent reflectors is seen the pre mount simon upper cambrian sedimentary sequence encountered has been defined as the type section of the middle run formation point counter analyses of typical middle run formation samples indicate that this sequence is similar in composition to middle proterozoic units associated with the midcontinent rift system in the lake superior region the newly discovered structure in ohio is also similar to half graben structures composing the lake superior basin portion of the midcontinent rift on the basis of similarities in lithology stratigraphy structure and proximity to regional gravity anomalies the middle run formation and its apparent half graben basin is proposed as evidence for the probable extension of the midcontinent rift system southward from its normally accepted termination in southeastern michigan into southwestern ohio

the role of rifting in the tectonic development of the midcontinent u s a abstract recent studies have proposed the existence of several major ancient rift zones in the midcontinent region of north america although the dating of some of these rifts and even the rift interpretations are subject to question an analysis of these paleo rifts reveals three major episodes of rifting keweenawan 1 1 b y b p eocambrian 600 m y b p and early mesozoic 200 m y b p the extent of these events documents that rifting has played a major role in the tectonic development of the midcontinent region this role goes well beyond the initial rifting event because these features display a strong correlation with paleozoic basins and a strong propensity for reactivation for example the eocambrian reelfoot rift was reactivated in the mesozoic to form the mississippi embayment and is the site of modern seismicity which suggests reactivation in a contemporary stress field of ene compression even though the importance of rifting can be established recognition of rifts and delineation of their complexities remain a major problem which requires more study

mimoc a global monthly isopycnal upper ocean climatology with mixed layers a monthly isopycnal mixed layer ocean climatology mimoc global from 0 to 1950 dbar is compared with other monthly ocean climatologies all available quality controlled profiles of temperature t and salinity s versus pressure p collected by conductivity temperature depth ctd instruments from the argo program ice tethered profilers and archived in the world ocean database are used mimoc provides maps of mixed layer properties conservative temperature absolute salinity sa and maximum p as well as maps of interior ocean properties sa and p to 1950 dbar on isopycnal surfaces a third product merges the two onto a pressure grid spanning the upper 1950 dbar adding more familiar potential temperature and practical salinity s maps all maps are at monthly 0 5 0 5 resolution spanning from 80 s to 90 n objective mapping routines used and described here incorporate an isobath following component using a fast marching algorithm as well as front sharpening components in both the mixed layer and on interior isopycnals recent data are emphasized in the mapping the goal is to compute a climatology that looks as much as possible like synoptic surveys sampled circa 2007 2011 during all phases of the seasonal cycle minimizing transient eddy and wave signatures mimoc preserves a surface mixed layer minimizes both diapycnal and isopycnal smoothing of s as well as preserves density structure in the vertical pycnoclines and pycnostads and the horizontal fronts and their associated currents it is statically stable and resolves water mass features fronts and currents with a high level of detail and fidelity

estimates and implications of surface eddy diffusivity in the southern ocean derived from tracer transport abstract near surface effective diffusivities associated with geostrophic eddies in the southern ocean are estimated by numerically monitoring the lengthening of idealized tracer contours as they are strained by surface geostrophic flow observed by satellite altimetry the resulting surface diffusivities show considerable spatial variability and are large 2000 m2 s 1 on the equatorward flank of the antarctic circumpolar current and are small 500 m2 s 1 at the jet axis regions of high and low effective diffusivity are shown to be collocated with regions of respectively weak and strong isentropic potential vorticity gradients the maps of diffusivity are used along with climatological estimates of surface wind stress and air sea buoyancy flux to estimate surface meridional residual flows and the relative importance of eulerian and eddy induced circulation in the streamwise averaged dynamics of the antarctic circumpolar current

consortium for continental reflection profiling michigan surveys reprocessing and results reprocessing of consortium for continental reflection profiling data from central michigan with emphasis on deconvolution and velocity filtering before stack and more detailed velocity analysis has resulted in greatly improved imaging of a previously reported keweenawan rift buried beneath the paleozoic of the michigan basin the seismic stratigraphy of the sub paleozoic units can now be related to the basin filling middle keweenawan volcanic sequence and the upper keweenawan clastic assemblage in greater detail important structural and stratigraphic features can be seen for the first time for example reprocessing has imaged an unconformity within the upper keweenawan it is possible some of these newly imaged features are associated with a late keweenawan compressive episode furthermore reprocessing also reveals previously unrecognized sub keweenawan structures including a deeply penetrating reflection which may represent a major crustal fault and possible weak reflections from midcrustal 25 km and moho 43 km depths

regional and temporal variability of lateral mixing in the north atlantic abstractgeostrophic eddies contribute to the mixing of heat carbon and other climatically important tracers a passive tracer driven by satellite derived surface velocity fields is used to study

evidence for a major late precambrian tectonic event rifting in the eastern midcontinent region united states recently acquired gravity and aeromagnetic data delineate a large linear gravity anomaly which extends through eastern kentucky and tennessee and coincides with a zone of complex high amplitude magnetic anomalies basement lithologies in the area can be interpreted as a bimodal volcanic suite which is locally peralkaline in nature these volcanics appear to be metamorphosed where they lie east of the grenville front suggesting they predate the grenville metamorphic event the available gravity aeromagnetic seismic refraction and petrologic data along with regional correlations suggest that the best tectonic interpretation of these data is that a keweenawan rift zone extended through the area this rift can be roughly outlined by the gravity high which is locally offset suggesting the presence of transform faults the boundaries of this rift have been locally reactivated and in fact a recent earthquake was located along its western boundary in northern kentucky

subtropical surface layer salinity budget and the role of mesoscale turbulence the subtropical north atlantic exhibits the saltiest surface waters of the open ocean eventually that water subducted from the surface and exported toward the equator as a subsurface salinity maximum s max forming the lower limb of the subtropical cell climatologically the winter subtropical surface water coinciding with the deepest mixed layer of 100 m is saltier and colder than the s max towed ctd measurements in march april 2013 a component of the field program spurs within the north atlantic subtropical surface salinity maximum reveal several relatively fresh warm anomalies which deviate strongly from climatological conditions these features introduce a large amount of freshwater into the subtropical region exceeding the amount introduced by local rain events observed scales and evolution of the features strongly suggest a connection to mesoscale dynamics this is supported by high resolution regional model output which produces an abundance of features that are similar in scale and structure to those observed it is hypothesized that turbulent transport in the surface ocean is a crucial process for setting mixed layer characteristics which spread into s max stratum high variability in the eke implies a high potential for interannual variability in the resulting s max water properties by ocean dynamics in addition to the variability caused by air sea fluxes this has likely consequences to the meridional transport of heat and freshwater of the subtropical cell in the north atlantic and to the larger scale ocean and climate system

energy balance model validation on the top of kilimanjaro tanzania using eddy covariance data eddy covariance data collected over a horizontal surface on the largest ice body on kilimanjaro tanzania over 26 29 july 2005 were used to assess the uncertainty of calculating sublimation with a surface energy balance seb model data required for input to the seb model were obtained from an existing automatic weather station surface temperatures that were solved iteratively by the seb model were used to compute emitted longwave radiation turbulent heat fluxes using the aerodynamic bulk method and the subsurface heat flux roughness lengths for momentum and temperature which were found to be the most important input parameters controlling the magnitude of modelled bulk method turbulent heat fluxes were obtained using eddy covariance data the roughness length for momentum was estimated to be 1 7 10 3 m while the length for temperature was one order of magnitude smaller modelled sensible and latent heat fluxes bulk method compared well to eddy covariance data with root mean square differences between 3 1 and 4 8 w m 2 for both turbulent heat fluxes modelled sublimation accounted for about 90 of observed ablation confirming that mass loss by melting is much less important than sublimation on the horizontal surfaces of the remaining plateau glaciers on kilimanjaro

a new approach to resolving climate cryosphere relations downscaling climate dynamics to glacier scale mass and energy balance without statistical scale linking 1 we present a novel combination of methods to quantify the local mass response of mountain glaciers to large scale circulation previously such multiscale approaches bypassed the mesoscale processes of the mountain induced atmospheric flow by statistical transfer functions or subgrid parameterizations and included simplified glacier mass balance mb models here we show on the basis of kilimanjaro east africa as a test case that a limited area atmospheric model lam and a process resolving mb model can be linked without statistical corrections at their interface this is evident from robust energy and mb patterns at the glacier surface regardless of whether the mb model is forced by 1 in situ meteorological measurements or 2 uncorrected output from the high resolution lam grid over the glacier area the latter is achieved by multiple grid nesting in the land atmosphere ocean domain of the lam since this setup resolves the mesoscale process space we also show the potential to increase knowledge of how dynamical thermodynamic and microphysical phenomena of the mountain induced flow affect glacier mb all these results are encouraging for future research because they demonstrate that a dynamical system which operates on very different space time scales can be quantified in a fully physical way if dynamic meteorology and glaciology are exploited in a complementary sense this will enhance the process understanding of forward problems glacier response to climate forcing and backward problems climate signal extraction from past extents of mountain glaciers

ocean eddy freshwater flux convergence into the north atlantic subtropics for a quasi steady state condition the water vapor flux from the ocean to atmosphere typical of the salty subtropics must be compensated by ocean processes that transfer freshwater into the evaporative regime observations of the north atlantic subtropical sea surface salinity maximum region frequently reveal the presence of eddies with distinct salinity temperature signatures of up to 0 2 psu 1 c with horizontal scales of up to 200 km using the surface layer salinity and meridional velocity from the simple ocean data assimilation soda reanalysis data we find that the eddy flux can accomplish 50 to 75 of the required freshwater convergence into the subtropical regime the rest being delivered by ekman transport convergence and therefore represents a significant component of the marine hydrological cycle interannual fluctuations of the eddy freshwater flux are reflected in sea surface salinity variability

one million cubic kilometers of fossil ice in valles marineris relicts of a 3 5 gy old glacial landsystem along the martian equator abstract self consistent landform assemblages suggest that valles marineris the giant valley system that stretches along the martian equator was entirely glaciated during late noachian to early hesperian times and still contains huge volumes of fossil ice some of these glacial landform assemblages are illustrated here with representative examples selected in three regions ius chasma central candor chasma and the junction between coprates chasma and capri chasma a morphological boundary separating an upper spur and gully morphology from a smooth basal escarpment has been spectacularly preserved along valley walls throughout valles marineris the boundary winds around topographic obstacles and displays long wavelength variations in elevation it is associated with lateral benches hanging valleys and truncated spurs comparisons with terrestrial analogs indicate that it is most reasonably interpreted as a glacial trimline chasma floors are covered by various kinds of terrains including hummocky terrains platy terrains lateral banks layered benches and a draping mantle landforms in these terrains and their spatial relationship with the interpreted trimline suggest that they correspond to various disintegration stages of an ancient glacial fill currently protected by a superficial cover of ablation till altogether these landforms and terrains compose a full glacial landsystem with wet based glaciers that were able to flow and slide over their beds it was most probably fed by ice accumulating at low elevations directly from the atmosphere onto valley floors and walls with only minor contributions from tributary glaciers flowing down from higher elevations similar fossil glacial landsystems dating back from the early martian history are to be expected in many other low latitude troughs such as chasmata chaos valleys impact craters and other basins

eddy induced particle dispersion in the near surface north atlantic abstractthis study investigates the anisotropic properties of the eddy induced material transport in the near surface north atlantic from two independent datasets one simulated from the sea surface height altimetry and one derived from real ocean surface drifters and systematically examines the interactions between the mean and eddy induced material transport in the region the lagrangian particle dispersion which is widely used to characterize the eddy induced tracer fluxes is quantified by constructing the spreading ellipses the analysis consistently demonstrates that this dispersion is spatially inhomogeneous and strongly anisotropic the spreading is larger and more anisotropic in the subtropical than in the subpolar gyre and the largest ellipses occur in the gulf stream vicinity even at times longer than half a year the spreading exhibits significant nondiffusive behavior in some parts of the domain the eddies in this study are defined as deviations from the long term time mean the contr

is the decline of ice on kilimanjaro unprecedented in the holocene glaciers on kilimanjaro s highest peak kibo are currently regarded as a persistent feature of the holocene here we synthesize all available measurements observations and our understanding of current processes on kibo gained from intensive research over the past decade to formulate an alternative hypothesis about the age of these ice fields this suggests a shorter discontinuous history of the tabular shaped glaciers on kibo s plateau where typical life cycles of the ice may last only a few hundred years if life cycles overlap they are likely the cause of the observed steps in the plateau glaciers thus it is likely that ice has come and gone repeatedly on kibo s summit plateau throughout the holocene such a cyclicity is supported by lake derived proxy records

kilimanjaro glaciers recent areal extent from satellite data and new interpretation of observed 20th century retreat rates 1 recent and long term variations in ice extent on kilimanjaro are investigated in the context of 20th century climate change in east africa quickbird satellite data show that the areal extent of glaciers on kilimanjaro is 2 51 km2 in february 2003 to assess glacier retreat on kilimanjaro two glacier systems are identified 1 plateau 5700 m and 2 slope 5700 m vertical wall retreat that governs the retreat of plateau glaciers is irreversible and changes in 20th century climate have not altered their continuous demise rapid retreat of slope glaciers at the beginning of the 20th century implies a strong departure from steady state conditions during this time this strong imbalance can only be explained by a sudden shift in climate which is not observed in the early 20th century results suggest glaciers on kilimanjaro are merely remnants of a past climate rather than sensitive indicators of 20th century climate change

what governs the north atlantic salinity maximum in a global gcm taking advantage of the rapid advance in ocean modeling this study investigates the sea surface salinity maximum in the north atlantic using results from a model of the consortium for estimating the circulation and climate of the ocean ecco salinity budget terms were computed at the model s integration time step and archived as monthly averages the simulated mixed layer salinity budget provides the first quantitative evidence for the ocean s role in governing the sea surface salinity maximum in the north atlantic our analysis reveals that ocean dynamics explains about half of the sea surface salinity variance being of equal importance as surface forcing the sea surface salinity maximum varies both seasonally and interannually as a consequence of interplay among surface flux advection and vertical entrainment contribution from eddies and small scale processes is relatively weak but not negligible these results may provide useful hints for the design and interpretation of future observations in the region citation qu t s gao and i fukumori 2011 what governs the north atlantic salinity maximum in a global gcm geophys res lett 38 l07602 doi 10 1029 2011gl046757

climatology and seasonality of upper ocean salinity a three dimensional view from argo floats primarily due to the constraints of observation technologies both field and satellite measurements our understanding of ocean salinity is much less mature compared to ocean temperature as a result the characterizations of the two most important properties of the ocean are unfortunately out of step the former is one generation behind the latter in terms of data availability and applicability this situation has been substantially changed with the advent of the argo floats which measure the two variables simultaneously on a global scale since early this century the first decade of argo acquired salinity data are analyzed here in the context of climatology and seasonality yielding the following main findings for the global upper oceans first the six well defined salty pools observed around 20 in each hemisphere of the pacific atlantic and indian oceans are found to tilt westward vertically from the sea surface to about 600 m depth forming six saline cores within the subsurface oceans second while potential temperature climatology decreases monotonically to the bottom in most places of the ocean the vertical distribution of salinity can be classified into two categories a double halocline type forming immediately above and below the local salinity maximum around 100 150 m depths in the tropical and subtropical oceans and a single halocline type existing at about 100 m depth in the extratropical oceans third in contrast to the midlatitude dominance for temperature seasonal variability of salinity in the oceanic mixed layer has a clear tropical dominance meanwhile it is found that a two mode structure with annual and semiannual periodicities can effectively penetrate through the upper ocean into a depth of 2000 m fourth signature of rossby waves is identified in the annual phase map of ocean salinity within 200 600 m depths in the tropical oceans revealing a strongly co varying nature of ocean temperature and salinity at specific depths these results serve as significant contributions to improving our knowledge on the haline aspect of the ocean climate