A Bivariate Time Series Approach to Anthropogenic Trend Detection in Hemispheric Mean Temperatures

A bivariate time series regression approach is used to model observed variations in hemispheric mean temperature over the period 1900-96. The regression equations include deterministic predictor variables and lagged values of the two predictands, and two different forms of this basic structure are employed. The deterministic predictors considered are simple linear trends, various climate model-generated time series based on different combinations of greenhouse gas, sulfate aerosol, and solar forcing, and the Southern Oscillation index (SOI). With linear trends as the only predictors, the best model is a fourth-order bivariate autoregressive model including lagged Southern Hemisphere (SH) to Northern Hemisphere (NH) dependence, as in previous work by Kaufmann and Stern. The estimated NH and SH trends are both + 0.67°C century-1, and both are highly statistically significant. If SOI is included as an additional predictor, however, a first-order time series model, with no SH to NH dependence, is an adequate fit to the data. This shows that SOI may be an important covariate in this kind of analysis. Further analysis uses climate model-generated forcing terms representing greenhouses gases, sulfate aerosols, and solar effects, as well as SOI. The statistical analysis makes extensive use of Bayes factors as a device for discriminating among a wide spectrum of possible models. The best fits to the data are obtained when all three forcing terms are included. Total sulfate aerosol forcing of 1.1 W m-2(with a corresponding climate sensitivity of ΔT2+ = 4.2cC) is preferred to -0.7 W m-2(with sensitivity of 2.3°C), but the Bayes factor discrimination between these cases is weak

A NEW CLIMATOLOGY OF THE AEROSOLS BASED ON THEIR INHERENT OPTICAL PROPERTIES FOR THE MERIS ATMOSPHERIC CORRECTIONS OVER OCEAN

ABSTRACT In the classical scheme of atmospheric corrections over oceans, the derivation of aerosol path radiances in the visible region is achieved using aerosol models deduced from the spectral dependency of atmospheric signals in the near-infrared domain. Standard models are generally included in the aerosol climatology, but the latter is not sufficient to describe variety of aerosols encountered over coastal areas. One way to extend this climatology consists in the generation of additional models. Coastal and inland CIMEL stations from AERONET (AErosol RObotic NETwork) offer an extensive data set of aerosol characteristics in marine environment through solar extinction and sky radiance measurements. Data collected by 25 stations during several years have been processed with an iterative method of aerosol phase functions retrieval developed at ULCO, to build-up a very large database (~7000 sequences). Statistical methods applied on this data set allowed to discard the wrong sequences and to suggest a classification in aerosol models through their inherent optical properties

Direct Resolution of the Interactions of a Hydrocarbon Gas with Adsorbed Surfactant Monolayers at the Water/Air Interface Using Neutron Reflectometry

We have directly resolved in the present work the interfacial composition during and after the interactions of a saturated atmosphere of oil vapor with soluble surfactant solutions at a planar water/air interface for the first time. Experiments were conducted on interactions of hexane vapor with solutions of alkyltrimethylammonium bromides and sodium dodecyl sulfate to observe the balance between cooperativity and competition of the components at the interface. In all cases, hexane adsorption was strongly enhanced by the presence of the surfactant, even at bulk surfactant concentrations four orders of magnitude below the critical micelle concentration. Cooperativity of the surfactant adsorption was observed only for sodium dodecyl sulfate at intermediate bulk concentrations, yet for all four systems, competition set in at higher concentrations, as hexane adsorption reduced the surfactant surface excess. The data fully supported the complete removal of hexane from the interface following venting of the system to remove the saturated atmosphere of oil vapor. These results help to identify future experiments that would elaborate and could explain the cooperativity of surfactant adsorption, such as on cationic surfactants with short alkyl chains and a broader series of anionic surfactants. This work holds relevance for oil recovery applications with foam, where there is a gas phase saturated with oil vapor

The Community Climate System Model version 3 (CCSM3)

Author Posting. © American Meteorological Society 2006. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 19 (2006): 2122–2143, doi:10.1175/JCLI3761.1.The Community Climate System Model version 3 (CCSM3) has recently been developed and released to the climate community. CCSM3 is a coupled climate model with components representing the atmosphere, ocean, sea ice, and land surface connected by a flux coupler. CCSM3 is designed to produce realistic simulations over a wide range of spatial resolutions, enabling inexpensive simulations lasting several millennia or detailed studies of continental-scale dynamics, variability, and climate change. This paper will show results from the configuration used for climate-change simulations with a T85 grid for the atmosphere and land and a grid with approximately 1° resolution for the ocean and sea ice. The new system incorporates several significant improvements in the physical parameterizations. The enhancements in the model physics are designed to reduce or eliminate several systematic biases in the mean climate produced by previous editions of CCSM. These include new treatments of cloud processes, aerosol radiative forcing, land–atmosphere fluxes, ocean mixed layer processes, and sea ice dynamics. There are significant improvements in the sea ice thickness, polar radiation budgets, tropical sea surface temperatures, and cloud radiative effects. CCSM3 can produce stable climate simulations of millennial duration without ad hoc adjustments to the fluxes exchanged among the component models. Nonetheless, there are still systematic biases in the ocean–atmosphere fluxes in coastal regions west of continents, the spectrum of ENSO variability, the spatial distribution of precipitation in the tropical oceans, and continental precipitation and surface air temperatures. Work is under way to extend CCSM to a more accurate and comprehensive model of the earth's climate system.We would like to acknowledge the substantial contributions to and support for the CCSM project from the National Science Foundation (NSF), the Department of Energy (DOE), the National Oceanic and Atmospheric Administration, and the National Aeronautics and Space Administration

Challenges in quantifying changes in the global water cycle

Human influences have likely already impacted the large-scale water cycle but natural variability and observational uncertainty are substantial. It is essential to maintain and improve observational capabilities to better characterize changes. Understanding observed changes to the global water cycle is key to predicting future climate changes and their impacts. While many datasets document crucial variables such as precipitation, ocean salinity, runoff, and humidity, most are uncertain for determining long-term changes. In situ networks provide long time-series over land but are sparse in many regions, particularly the tropics. Satellite and reanalysis datasets provide global coverage, but their long-term stability is lacking. However, comparisons of changes among related variables can give insights into the robustness of observed changes. For example, ocean salinity, interpreted with an understanding of ocean processes, can help cross-validate precipitation. Observational evidence for human influences on the water cycle is emerging, but uncertainties resulting from internal variability and observational errors are too large to determine whether the observed and simulated changes are consistent. Improvements to the in situ and satellite observing networks that monitor the changing water cycle are required, yet continued data coverage is threatened by funding reductions. Uncertainty both in the role of anthropogenic aerosols, and due to large climate variability presently limits confidence in attribution of observed changes

Natriuretic peptides and integrated risk assessment for cardiovascular disease: an individual-participant-data meta-analysis

BACKGROUND: Guidelines for primary prevention of cardiovascular diseases focus on prediction of coronary heart disease and stroke. We assessed whether or not measurement of N-terminal-pro-B-type natriuretic peptide (NT-proBNP) concentration could enable a more integrated approach than at present by predicting heart failure and enhancing coronary heart disease and stroke risk assessment. METHODS: In this individual-participant-data meta-analysis, we generated and harmonised individual-participant data from relevant prospective studies via both de-novo NT-proBNP concentration measurement of stored samples and collection of data from studies identified through a systematic search of the literature (PubMed, Scientific Citation Index Expanded, and Embase) for articles published up to Sept 4, 2014, using search terms related to natriuretic peptide family members and the primary outcomes, with no language restrictions. We calculated risk ratios and measures of risk discrimination and reclassification across predicted 10 year risk categories (ie, <5%, 5% to <7·5%, and ≥7·5%), adding assessment of NT-proBNP concentration to that of conventional risk factors (ie, age, sex, smoking status, systolic blood pressure, history of diabetes, and total and HDL cholesterol concentrations). Primary outcomes were the combination of coronary heart disease and stroke, and the combination of coronary heart disease, stroke, and heart failure. FINDINGS: We recorded 5500 coronary heart disease, 4002 stroke, and 2212 heart failure outcomes among 95 617 participants without a history of cardiovascular disease in 40 prospective studies. Risk ratios (for a comparison of the top third vs bottom third of NT-proBNP concentrations, adjusted for conventional risk factors) were 1·76 (95% CI 1·56-1·98) for the combination of coronary heart disease and stroke and 2·00 (1·77-2·26) for the combination of coronary heart disease, stroke, and heart failure. Addition of information about NT-proBNP concentration to a model containing conventional risk factors was associated with a C-index increase of 0·012 (0·010-0·014) and a net reclassification improvement of 0·027 (0·019-0·036) for the combination of coronary heart disease and stroke and a C-index increase of 0·019 (0·016-0·022) and a net reclassification improvement of 0·028 (0·019-0·038) for the combination of coronary heart disease, stroke, and heart failure. INTERPRETATION: In people without baseline cardiovascular disease, NT-proBNP concentration assessment strongly predicted first-onset heart failure and augmented coronary heart disease and stroke prediction, suggesting that NT-proBNP concentration assessment could be used to integrate heart failure into cardiovascular disease primary prevention. FUNDING: British Heart Foundation, Austrian Science Fund, UK Medical Research Council, National Institute for Health Research, European Research Council, and European Commission Framework Programme 7

The extratropical upper troposphere and lower stratosphere

The extratropical upper troposphere and lower stratosphere (Ex-UTLS) is a transition region between the stratosphere and the troposphere. The Ex-UTLS includes the tropopause, a strong static stability gradient and dynamic barrier to transport. The barrier is reflected in tracer profiles. This region exhibits complex dynamical, radiative, and chemical characteristics that place stringent spatial and temporal requirements on observing and modeling systems. The Ex-UTLS couples the stratosphere to the troposphere through chemical constituent transport (of, e.g., ozone), by dynamically linking the stratospheric circulation with tropospheric wave patterns, and via radiative processes tied to optically thick clouds and clear-sky gradients of radiatively active gases. A comprehensive picture of the Ex-UTLS is presented that brings together different definitions of the tropopause, focusing on observed dynamical and chemical structure and their coupling. This integral view recognizes that thermal gradients and dynamic barriers are necessarily linked, that these barriers inhibit mixing and give rise to specific trace gas distributions, and that there are radiative feedbacks that help maintain this structure. The impacts of 21st century anthropogenic changes to the atmosphere due to ozone recovery and climate change will be felt in the Ex-UTLS, and recent simulations of these effects are summarized and placed in context

Neurogenic mechanisms in bladder and bowel ageing

The prevalence of both urinary and faecal incontinence, and also chronic constipation, increases with ageing and these conditions have a major impact on the quality of life of the elderly. Management of bladder and bowel dysfunction in the elderly is currently far from ideal and also carries a significant financial burden. Understanding how these changes occur is thus a major priority in biogerontology. The functions of the bladder and terminal bowel are regulated by complex neuronal networks. In particular neurons of the spinal cord and peripheral ganglia play a key role in regulating micturition and defaecation reflexes as well as promoting continence. In this review we discuss the evidence for ageing-induced neuronal dysfunction that might predispose to neurogenic forms of incontinence in the elderly

Télédétection des aérosols au dessus des terres émergées à l'aide des capteurs "couleur de l'eau" et applications

Le travail de thèse s'est organisé autour de l'application de l'algorithme de télédétection des aérosols au-dessus des terres émergées développé pour le capteur ENVISAT/MERIS sur une base de données du capteur SeaSTAR/SeaWiFS. La télédétection des aérosols au-dessus des terres émergées est basée sur la détection des cibles de végétation sombre dans le bleu et le rouge (DDV) à l'aide d'un seuil sur l'ARVI. Le point critique de l'algorithme est la faible couverture du produit aérosol (inférieur à 2% des terres émergées). Pour remédier à cette faible couverture, le concept de DDV a été étendu à des surfaces plus brillantes appelées LARS. La réflectance des LARS est modélisée grâce à la linéarité de la réflectance de surface en fonction de l'ARVI. Une étude statistique sur les données SeaWiFS basée sur l'homogénéitéspatiale des aérosols sur ces petites sous scènes a permis de confirmer le nouveau modèle établi par HYGEOS sur les données MERIS. La comparaison des produits aérosols SeaWiFS avec les données photométriques du réseau AERONET montre une bonne inversion des épaisseurs optiques des aérosols dans le bleu et une surestimation des épaisseurs optiques des aérosols dans le rouge. Nous avons maintenant un produit aérosol opérationnel sur les données SeaWiFS. Dans le cadre de deux projets européens, nous avons été amenés à appliquer l'algorithme de télédétection des aérosols au-dessus des terres émergées. Le projet EXPER/PF porte sur la qualité de l'air et la possibilité de conversion des épaisseurs optiques des aérosols en mesure de "Particulate Matter" à l'aide d'une large base de données sur les particules et des données auxiliaires. Le projet SISCAL concerne la "couleur de l'eau" et l'application de la télédétection des aérosols au-dessus des terres émergées dans une approche innovante des corrections atmosphériques au-dessus des eaux intérieures.This work is organized on the application of the aerosol remote sensing over land algorithm developed for the ENVISAT/MERIS sensor on a large database of SeaSTAR/SeaWiFS sensor. The aerosol remote sensing over land is based on the DDV (Dense Dark Vegetation) detection selected with the ARVI thanks to the darkness of the DDV in the blue and the red. The critical point of the algorithm is the weak coverage of the aerosol product (around 2% of the land). To fix this coverage problem, the DDV concept has been extended to brighter surfaces called LARS (Land Aerosol Remote Sensing). The LARS reflectance is modelized thanks to the linearity between the surface reflectance and the ARVI. A statistical study based on the aerosol spatial homogeneity over small SeaWiFS subscenes allows confirming the new model established by HYGEOS on MERIS data. The comparison of the SeaWiFS aerosol product with AERONET data shows a good retrieval of the aerosol optical thickness in the blue and an overestimation of the aerosol optical thickness in the red. Now, we have an operational aerosol product with SeaWiFS. In the frame of two European projects, we applied the aerosol remote sensing over land algorithm. The EXPER/PF project relies on air quality and the possibility of the conversion of the aerosol optical thickness into PM with the help of a large database on particles and auxiliary data. The SISCAL project relies on the "water color" and the application of the aerosol remote sensing over land for an innovative approach of the atmospheric correction over inland waters.BOULOGNE-BU Droit Lettres (621602101) / SudocSudocFranceF

Estimation du P.A.R. (Photosynthetically active radiation) dans les eaux du cas II par télédétection spatiale

BOULOGNE-BU Droit Lettres (621602101) / SudocSudocFranceF