Impact of high frequency waves on the ocean altimeter range bias

New aircraft observations are presented on the range determination error in satellite altimetry associated with ocean waves. Laser-based measurements of the cross correlation between the gravity wave slope and elevation are reported for the first time. These observations provide direct access to a long, O(10 m), gravity wave statistic central to nonlinear wave theory prediction of the altimeter sea state bias. Coincident Ka-band radar scattering data are used to estimate an electromagnetic (EM) range bias analogous to that in satellite altimetry. These data, along with ancillary wind and wave slope variance estimates, are used alongside existing theory to evaluate the extent of long- versus short-wave, O(cm), control of the bias. The longer wave bias contribution to the total EM bias is shown to range from 25 to as much as 100%. Moreover, on average the term is linearly related to wind speed and to the gravity wave slope variance, consistent with WNL theory. The EM bias associated with interactions between long and short waves is obtained assuming the effect is additive to the independently observed long-wave factor. This second component is also a substantial contributor, is observed to be quadratic in wind speed or wave slope, and dominates at moderate wind speeds. The behavior is shown to be consistent with EM bias prediction based in hydrodynamic modulation theory. Study implications for improved correction of the on-orbit satellite sea state bias are discussed

Sea state bias in altimeter sea level estimates determined by combining wave model and satellite data

This study documents a method for increasing the precision of satellite-derived sea level measurements. Results are achieved using an enhanced three-dimensional (3-D) sea state bias (SSB) correction model derived from both Jason-1 altimeter ocean observations (i.e., sea state and wind) and estimates of mean wave period from a numerical ocean wave model, NOAA’s WAVEWATCH III. A multiyear evaluation of Jason-1 data indicates sea surface height variance reduction of 1.26 (±0.2) cm2 in comparison to the commonly applied two-parameter SSB model. The improvement is similar for two separate variance reduction metrics and for separate annual data sets spanning 2002–2004. Spatial evaluation of improvement shows skill increase at all latitudes. Results indicate the new model can reduce the total Jason-1 and Jason-2 altimeter range error budgets by 7.5%. In addition to the 2-D (two-dimensional) and 3-D model differences in correcting the range for wavefield variability, mean model regional differences also occur across the globe and indicate a possible 1–2 cm gradient across ocean basins linked to the zonal variation in wave period (short fetch and period in the west, swells and long period in the east). Overall success of this model provides first evidence that operational wave modeling can support improved ocean altimetry. Future efforts will attempt to work within the limits of wave modeling capabilities to maximize their benefit to Jason-1 and Jason-2 SSB correction methods

Sea surface salinity variability from a simplified mixed layer model of the global ocean

International audienceA bi-dimensional mixed layer model (MLM) of the global ocean is used to investigate the sea surface salinity (SSS) balance and variability at daily to seasonal scales. Thus a simulation over an average year is performed with daily climatological forcing fields. The forcing dataset combines air-sea fluxes from a meteorological model, geostrophic currents from satellite altimeters and in situ data for river run-offs, deep temperature and salinity. The model is based on the "slab mixed layer" formulation, which allows many simplifications in the vertical mixing representation, but requires an accurate estimate for the Mixed Layer Depth. Therefore, the model MLD is obtained from an original inversion technique, by adjusting the simulated temperature to input sea surface temperature (SST) data. The geographical distribution and seasonal variability of this "effective" MLD is validated against an in situ thermocline depth. This comparison proves the model results are consistent with observations, except at high latitudes and in some parts of the equatorial band. The salinity balance can then be analysed in all the remaining areas. The annual tendency and amplitude of each of the six processes included in the model are described, whilst providing some physical explanations. A map of the dominant process shows that freshwater flux controls SSS in most tropical areas, Ekman transport in Trades regions, geostrophic advection in equatorial jets, western boundary currents and the major part of subtropical gyres, while diapycnal mixing leads over the remaining subtropical areas and at higher latitudes. At a global scale, SSS variations are primarily caused by horizontal advection (46%), then vertical entrainment (24%), freshwater flux (22%) and lateral diffusion (8%). Finally, the simulated SSS variability is compared to an in situ climatology, in terms of distribution and seasonal variability. The overall agreement is satisfying, which confirms that the salinity balance is reliable. The simulation exhibits stronger gradients and higher variability, due to its fine resolution and high frequency forcing. Moreover, the SSS variability at daily scale can be investigated from the model, revealing patterns considerably different from the seasonal cycle. Within the perspective of the future satellite missions dedicated to SSS retrieval (SMOS and Aquarius/SAC-D), the MLM could be useful for determining calibration areas, as well as providing a first-guess estimate to inversion algorithms

Emergent conservation outcomes of shared risk perception in human‐wildlife systems

Human perception of risks related to economic damages caused by nearby wildlife can be transmitted through social networks. Understanding how sharing risk information within a human community alters the spatial dynamics of human‐wildlife interactions has important implications for the design and implementation of effective conservation actions. We developed an agent‐based model that simulates farmer livelihood decisions and activities in an agricultural landscape shared with a population of a generic wildlife species (wildlife‐human interactions in shared landscapes [WHISL]). In the model, based on risk perception and economic information, farmers decide how much labor to allocate to farming and whether and where to exclude wildlife from their farms (e.g., through fencing, trenches, or vegetation thinning). In scenarios where the risk perception of farmers was strongly influenced by other farmers, exclusion of wildlife was widespread, resulting in decreased quality of wildlife habitat and frequency of wildlife damages across the landscape. When economic losses from encounters with wildlife were high, perception of risk increased and led to highly synchronous behaviors by farmers in space and time. Interactions between wildlife and farmers sometimes led to a spillover effect of wildlife damage displaced from socially and spatially connected communities to less connected neighboring farms. The WHISL model is a useful conservation‐planning tool because it provides a test bed for theories and predictions about human‐wildlife dynamics across a range of different agricultural landscapes.Resultados Emergentes de Conservación de la Percepción Compartida sobre Riesgos en los Sistemas Humanos – FaunaResumenLa percepción humana de los riesgos relacionados con los daños económicos causados por la fauna vecina puede transmitirse por medio de las redes sociales. El entendimiento de cómo la propagación de la información sobre riesgos dentro de una comunidad humana altera las dinámicas espaciales de las interacciones humanos – fauna tiene implicaciones importantes para el diseño e implementación de las acciones de conservación efectiva. Desarrollamos un modelo basado en agentes que simula las decisiones y las actividades de subsistencia de los agricultores en un paisaje agrícola compartido con una especie genérica de fauna (interacciones humanos – fauna en paisajes compartidos [WHISL, en inglés]). En el modelo, con base en la percepción del riesgo y en la información económica, los agricultores decidieron cuánto trabajo asignar a la agricultura y si y en dónde excluir a la fauna de sus parcelas (por ejemplo, por medio de cercas, fosas o la reducción de la vegetación). En los escenarios en los que la percepción de riesgo de los agricultores estuvo fuertemente influenciada por otros agricultores, la exclusión de la fauna estuvo generalizada, lo que resultó en una disminución de la calidad del hábitat de la fauna y en la frecuencia de daños causados por los animales a lo largo del paisaje. Cuando las pérdidas económicas causadas por los encuentros con la fauna fueron altas, la percepción del riesgo incrementó y resultó en comportamientos altamente sincrónicos adoptados por los agricultores en el tiempo y el espacio. Las interacciones entre la fauna y los agricultores a veces resultaron en un efecto de derrama de daños causados por la fauna desplazada de las comunidades conectadas social y espacialmente hacia parcelas vecinas con una menor conexión. El modelo WHISL es una herramienta útil para la planificación de la conservación porque proporciona una plataforma de experimentación para las teorías y predicciones sobre las dinámicas humano – fauna en una extensión geográfica de diferentes paisajes agrícolas.摘要人类对附近野生动物造成经济损失的风险感知可以通过社会网络传播。理解人类社会中共享风险信息如何改变人类与野生动物互作的空间动态, 对设计和实施有效保护行动具有重要意义。我们开发了一种基于主体的模型, 以模拟存在野生动物种群的农业景观中农场主的生计决策和活动 (共享景观中的野生动物‐人类互作) 。在这个模型中, 农场主根据风险感知和经济方面的信息来决定如何分配农作劳动、是否以及在哪里将野生动物驱逐到农场之外 (如通过建围栏、挖沟渠或减少植被覆盖) 。在农场主的风险感知受到其它农场主强烈影响的情况下, 农场主普遍会驱逐野生动物, 导致整个景观中野生动物生境质量下降, 野生动物造成破坏的频率也下降。当遭遇野生动物造成的经济损失较高时, 农场主对风险的感知会增加, 从而导致他们的行为在时空上高度同步。野生动物和农场主之间的互作有时候也会产生溢出效应, 使野生动物造成的破坏从社会及空间上紧密联系的社区转移到联系不够紧密的临近农场。本研究的共享景观中野生动物‐人类互作模型是一种有效的保护规划工具, 为不同农业景观中人类‐野生动物动态变化的理论和预测提供了试验平台。 【翻译: 胡怡思; 审校: 聂永刚】Article impact statement: Sharing of risk perception in social networks alters spatial patterns of human‐wildlife interactions, sometimes creating spillover effects.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156460/2/cobi13473_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156460/1/cobi13473.pd

Multidisciplinary characterisation of sedimentary processes in a recent maar lake (Lake Pavin, French Massif Central) and implication for natural hazards

Sedimentation processes occurring in the most recent maar lake of the French Massif Central (Lake Pavin) are documented for the first time based on high resolution seismic reflection and multibeam bathymetric surveys and by piston coring and radiocarbon dating on a sediment depocentre developed on a narrow sub aquatic plateau. This new data set confirms the mid Holocene age of maar lake Pavin formation at 6970±60 yrs cal BP and highlights a wide range of gravity reworking phenomena affecting the basin. In particular, a slump deposit dated between AD 580–640 remoulded both mid-Holocene lacustrine sediments, terrestrial plant debris and some volcanic material from the northern crater inner walls. Between AD 1200 and AD 1300, a large slide scar mapped at 50 m depth also affected the southern edge of the sub aquatic plateau, suggesting that these gas-rich biogenic sediments (laminated diatomite) are poorly stable. Although several triggering mechanisms can be proposed for these prehistoric sub-aquatic mass wasting deposits in Lake Pavin, we argue that such large remobilisation of gas-rich sediments may affect the gas stability in deep waters of meromictic maar lakes. This study highlights the need to further document mass wasting processes in maar lakes and their impacts on the generation of waves, favouring the development of dangerous (and potentially deadly) limnic eruptions

A New Tool Preliminary Assessment on Temporal-Comorbidity Adjusted Risk of Emergency Readmission (T-CARER)

Patients’ comorbidities, operations and complications can be associated with reduced long-term survival probability and increased healthcare utilisation. The aim of this research was to produce an adjusted case-mix model of comorbidity risk and develop a user-friendly toolkit to encourage public adaptation and incremental development.It has been shown in healthcare research that demographics, temporal dimensions, length-of-stay and time between admissions, can noticeably improve the statistical measures related to comorbidities. The proposed model incorporates temporal aspects, medical procedures, demographics, and admission details, as well as diagnoses.The research resulted in the development of Temporal-Comorbidity Adjusted Risk of Emergency Readmission (T-CARER) model using routinely collected hospital data

Deep endometriosis infiltrating the recto-sigmoid: critical factors to consider before management

Mauricio Simoes Abrao1,, Felice Petraglia2, Tommaso Falcone3, Joerg Keckstein4, Yutaka Osuga5, and Charles Chapron6,7,8 Endometriosis Division, Obstetrics and Gynecological Department – Sao Paulo University, Sao Paulo, Brazil Obstetrics and Gynecology, Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy Obstetrics, Gynecology andWomen's Health Institute, Cleveland Clinic, Cleveland, OH, USA Department of Obstetrics and Gynecology, Center for Endometriosis, Villach Hospital, Villach, Austria Department of Obstetrics and Gynecology, Faculty of Medicine, University of Tokyo, Hongo, Bunkyo, Tokyo, Japan Universite Paris Descartes, Sorbonne Paris Cite, Faculte de Medecine, Assistance Publique – Hopitaux de Paris (APHP), Groupe Hospitalier Universitaire (GHU) Ouest, Centre Hospitalier Universitaire (CHU) Cochin, Department of Gynecology Obstetrics II and Reproductive Medicine, 75679 Paris, France Institut Cochin, Universite Paris Descartes, Sorbonne Paris Cite CNRS (UMR 8104), Paris, France Inserm, Universite Paris Descartes, Sorbonne Paris Cite, Unite de recherche U1016, Paris, Franc

Remote Inspection, Measurement and Handling for LHC

Personnel access to the LHC tunnel will be restricted to varying extents during the life of the machine due to radiation, cryogenic and pressure hazards. The ability to carry out visual inspection, measurement and handling activities remotely during periods when the LHC tunnel is potentially hazardous offers advantages in terms of safety, accelerator down time, and costs. The first applications identified were remote measurement of radiation levels at the start of shut-down, remote geometrical survey measurements in the collimation regions, and remote visual inspection during pressure testing and initial machine cool-down. In addition, for remote handling operations, it will be necessary to be able to transmit several real-time video images from the tunnel to the control room. The paper describes the design, development and use of a remotely controlled vehicle to demonstrate the feasibility of meeting the above requirements in the LHC tunnel. Design choices are explained along with operating experience to-date and future development plans

Holocene earthquake-triggered mass-wasting events recorded in the sediments of Lake Puyehue (South-Central Chile)

Despite South-Central Chile’s high seismicity and the occurrence of earth’s largest instrumentally recorded earthquake (AD 1960; Mw: 9.5), paleoseismic data is still scarce for this region. In this study, very high-resolution reflection seismic profiles (3.5 kHz) in Lake Puyehue (41°S) were utilized to trace giant seismic events back into time. The seismic profiles show repeated occurrences of multiple mass-wasting deposits (slumps, debris flows, homogenites) occurring at a same seismic-stratigraphic horizon, indicating that they are coeval and caused by a single mass-wasting event of basin-wide importance. An age-depth model, based on 9 AMS radiocarbon datings and varve-counting on an 11 m-long sediment core, has been used to develop a “seismic chronostratigraphy”. It allows dating of the mass-wasting events by interpolation between dated seismic horizons to the distal parts of the mass-wasting deposits. The mass-wasting events are assumed to be earthquake-triggered because:The recentmost mass-wasting events correlate with the devastating historical earthquakes of AD 1575 and AD 1960.Synchronicity of multiple slope failures (mass-wasting events) requires a strong regional trigger, such as an earthquake. Consequently, local slope oversteepening at delta fronts or local fluid expulsion could not initiate such widespread events.South-Central Chile has been historically subjected to several strong (M > 8) subduction earthquakes and subduction processes have been constantly active since Mesozoic times.Multiple slope failures occur at water depths > 70 m, which rules out shallow instability triggers, such as storm wave action and lake-level fluctuations.This study reveals nine paleoseismic events during the Holocene with a mean recurrence rate of about 1000 yr, but with an overall relatively aperiodic occurrence (ranging between 400-2000 yrs.). The most prominent event took place around 1660 cal. yr. BP, evidenced by at least 29 simultaneous mass-movements and a homogenite deposit. Quantitative comparison of mass-wasting events related to the historical earthquakes of AD 1960 and AD 1575 showed significant differences (respectively 17 and 4 observed mass-wasting deposits) although these earthquakes are assumed to have had a comparable strength. This can be attributed to a lowered sedimentation rate on the potentially unstable slopes in the period 3000 cal. yr. BP – 500 cal. yr. BP, which would have made lacustrine earthquake recording less likely in AD 1575. The absence of mass-wasting deposits associated with other historical earthquakes (e.g.: AD 1737 (Ms: 7.5) and AD 1837 (Ms: 8)) indicates that only mega-earthquakes (Mw >8.5) within a range of about 300 km are recorded in the sedimentary sequence of Lake Puyehue.Reflection seismic profiles also show vertical fluidisation structures with large-scale sediment injections, which disturb the upper sedimentary sequences. The top of these fluidisation structures and diverse deformation levels could be spatially linked to seismically induced mass-wasting deposits and consequently indicate an additional method for lacustrine paleo-earthquake tracing.Several reconaissance seismic surveys on other glacigenic lakes in the Chilean Lake District also show promising paleoseismic records, which will offer the opportunity to correlate lacustrine records to reveal South-Central Chile’s paleoseismic history in detail and the earthquake registration capacities of its glacigenic lakes