An empirical parameterization of subsurface entrainment temperature for improved SST anomaly simulations in an intermediate ocean model

An empirical model for the temperature of subsurface water entrained into the ocean mixed layer (Te) is presented and evaluated to improve sea surface temperature anomaly (SSTA) simulations in an intermediate ocean model (IOM) of the tropical Pacific. An inverse modeling approach is adopted to estimate Te from an SSTA equation using observed SST and simulated upper-ocean currents. A relationship between Te and sea surface height (SSH) anomalies is then obtained by utilizing a singular value decomposition (SVD) of their covariance. This empirical scheme is able to better parameterize Te anomalies than other local schemes and quite realistically depicts interannual variability of Te, including a nonlocal phase lag relation of Te variations relative to SSH anomalies over the central equatorial Pacific. An improved Te parameterization naturally leads to better depiction of the subsurface effect on SST variability by the mean upwelling of subsurface temperature anomalies. As a result, SSTA simulations are significantly improved in the equatorial Pacific; a comparison with other schemes indicates that systematic errors of the simulated SSTAs are significantly small—apparently due to the optimized empirical Teparameterization. Cross validation and comparisons with other model simulations are made to illustrate the robustness and effectiveness of the scheme. In particular it is demonstrated that the empirical Te model constructed from one historical period can be successfully used to improve SSTA simulations in another

Resolución de los problemas de autenticación a una aplicación web

Con la Era del Internet y del uso masivo e imprescindible de los ordenadores en los negocios han aparecido nuevos problemas vinculados con la seguridad. Para aprovechar esta nueva tecnología que es el Internet, para robar los datos personales de los usuarios o para entrar en sistemas informáticos sin tener derecho, los piratas han desarrollado nuevas tecnologías como el Scam, el Spam y el Phishing entre otros. Durante estos últimos años, también se ha visto la aparición de técnicas para luchar frente a las amenazas previamente citadas. La seguridad informática es un dominio con una expansión muy importante. Para los usuarios particulares, el hecho de que alguien le roben sus datos puede ser preocupante, pero en el caso de una empresa, puede devenir en problemas realmente criticos. Si unos datos confidenciales son revelados, es la credibilidad de la empresa la que puede encontrarse en peligro. Por ejemplo, si la lista de los clientes de una empresa es descubierta por una persona externa o si las informaciones referentes a las ventas son divulgadas al publico o a un competidor, las consecuencias pueden ser muy graves incluyendo demandas legales, perdida de clientes, perdida de competitividad. Uno de los aspectos básicos de la seguridad es la autenticación de los usuarios. Muchas herramientas de administración estan disponible en Internet para permitir a las personas acceder a las aplicaciones de diferentes maneras siguiendo las políticas de la empresa. El sistema de autenticación se convierte entonces en un punto critico de sus desarrollos. Por eso se debe definir de manera especifica los derechos de acceso de los usuarios y asegurarse de prohibir el acceso a las personas no autentificadas. Desde hace mucho tiempo, existen varios métodos de autenticacion, pero nuevas soluciones han también aparecido desde hace poco, pensadas y desarrolladas para el uso de Internet, desde cualquier dispositivo y desde cualquier localidad. El objetivo de este Proyecto de Fin de Carrera es de resolver los problemas de autenticación de los usuarios a una aplicación web dentro de una empresa. Contempla la selección del método de autenticación, y su puesta en producción como nueva herramienta utilizable por los empleados de la empresa

Can the Weak Surface Currents of the Cape Verde Frontal Zone Be Measured With Altimetry?

Three data types are compared in the low-current-velocity regime in the southeastern North Atlantic, between 12-degrees-N and 30-degrees-N, 29-degrees-W and 18-degrees-W: Geosat altimetric sea level and derived surface geostrophic velocities, shallow current meter velocities, and dynamic heights derived from hydrographic data from cruises 4, 6, and 9 of the research vessel Meteor. The four current meter daily time series, at depths around 200 m, were smoothed over 1 month; the altimetric geostrophic velocities were computed from sea surface slopes over 142 km every 17 days. The correlation coefficients between the current meter and altimetric geostrophic velocities range between 0.64 and 0.90 for the moorings near 29-degrees-N but between 0.32 and 0.71 for the two around 21-degrees-N; the associated rms discrepancies between the two measurement types range between 1.5 and 4.4 cm/s, which is 49% to 127% of the rms of the respective current meter time series. Dynamic heights relative to 1950 dbar for the months of November 1986 (d(M4)), November 1987 (d(M6)), and February 1989 (d(M9)) were computed from Meteor cruises 4, 6, and 9. Both dynamic heights and altimetric heights (h(M4), h(M6), h(M9)) were averaged over 1-degrees boxes for the duration of each cruise. Differences d(M4) - d(M6) and d(M9) - d(M6) were computed only at bins where at least one station from both cruises existed, Assuming that dynamic heights d in dynamic centimeters are equivalent to sea level h in centimeters, the standard deviation sigma of the differences ((h(M4) - h(M6)) - (d(M4) - d(M6))) and corresponding M9 - M6 values was 2.1 cm. This value (squared) is only 13% of the (5.8 cm)2 variance of the dynamic height differences and is indistinguishable from the 2.7- to 5.6-cm natural variability of sea level in the area expected between the times when the ship and the satellite sampled the ocean. The areally averaged discrepancy for M9 - M6 was only 0.7 cm, but the corresponding value for M4 - M6 was 5.2 cm. A systematic difference between the water vapor corrections used before and after July 1987 is responsible for the M4 - M6 difference. The average M4 - M6 discrepancy is only 0.1 cm using the Fleet Numerical Oceanography Center correction, with a standard deviation of 3.1 cm. In spite of the underlying differences in sampling and physics, including unknown barotropic components not included in our hydrographic dynamic heights, and in data errors, including water vapor, ionospheric, and orbital effects on the altimetry, consistent interannual changes of the mean sea level from the independently obtained altimetric and hydrographic data sets are obtained, and correlated seasonal changes in surface currents are observed with both altimetry and current meters

Resolución de los problemas de autenticación a una aplicación web

Con la Era del Internet y del uso masivo e imprescindible de los ordenadores en los negocios han aparecido nuevos problemas vinculados con la seguridad. Para aprovechar esta nueva tecnología que es el Internet, para robar los datos personales de los usuarios o para entrar en sistemas informáticos sin tener derecho, los piratas han desarrollado nuevas tecnologías como el Scam, el Spam y el Phishing entre otros. Durante estos últimos años, también se ha visto la aparición de técnicas para luchar frente a las amenazas previamente citadas. La seguridad informática es un dominio con una expansión muy importante. Para los usuarios particulares, el hecho de que alguien le roben sus datos puede ser preocupante, pero en el caso de una empresa, puede devenir en problemas realmente criticos. Si unos datos confidenciales son revelados, es la credibilidad de la empresa la que puede encontrarse en peligro. Por ejemplo, si la lista de los clientes de una empresa es descubierta por una persona externa o si las informaciones referentes a las ventas son divulgadas al publico o a un competidor, las consecuencias pueden ser muy graves incluyendo demandas legales, perdida de clientes, perdida de competitividad. Uno de los aspectos básicos de la seguridad es la autenticación de los usuarios. Muchas herramientas de administración estan disponible en Internet para permitir a las personas acceder a las aplicaciones de diferentes maneras siguiendo las políticas de la empresa. El sistema de autenticación se convierte entonces en un punto critico de sus desarrollos. Por eso se debe definir de manera especifica los derechos de acceso de los usuarios y asegurarse de prohibir el acceso a las personas no autentificadas. Desde hace mucho tiempo, existen varios métodos de autenticacion, pero nuevas soluciones han también aparecido desde hace poco, pensadas y desarrolladas para el uso de Internet, desde cualquier dispositivo y desde cualquier localidad. El objetivo de este Proyecto de Fin de Carrera es de resolver los problemas de autenticación de los usuarios a una aplicación web dentro de una empresa. Contempla la selección del método de autenticación, y su puesta en producción como nueva herramienta utilizable por los empleados de la empresa

Design of a Bandpass Filter with an Absorptive Stopband for Multifeed Antenna Systems

This paper presents a filtering solution for enhanced multiband and multisource antenna systems used for space applications. Covering a large surface of the Earth necessitates numerous apertures closely spaced over a reflector antenna. Since these multi-feed systems generally employ multiple bands and multiple polarizations, these architectures induce significant coupling and consequently influence the effectiveness of the solution. The approach of signal retransmission with a controlled phase is proven to be efficient despite a delay concern. On the other hand, as shown in this paper, dissipating the reflected signal can also provide an adequate solution. For this second approach, we have synthesized a two-band filter, one passing the signal, the other absorbing it. This behaviour fits the desired antenna performance and improves the isolation between the two channels. We have designed such a filter and a comparison was made between the two approaches to investigate and derive the efficiency and benefit of each solution. A resized version of the microwave filter with dual behaviour has been manufactured and characterized for experimental verification

Climate fluctuations of tropical coupled system: The role of ocean dynamics

The tropical oceans have long been recognized as the most important region for large-scale ocean–atmosphere interactions, giving rise to coupled climate variations on several time scales. During the Tropical Ocean Global Atmosphere (TOGA) decade, the focus of much tropical ocean research was on understanding El Niño–related processes and on development of tropical ocean models capable of simulating and predicting El Niño. These studies led to an appreciation of the vital role the ocean plays in providing the memory for predicting El Niño and thus making seasonal climate prediction feasible. With the end of TOGA and the beginning of Climate Variability and Prediction (CLIVAR), the scope of climate variability and predictability studies has expanded from the tropical Pacific and ENSO-centric basis to the global domain. In this paper the progress that has been made in tropical ocean climate studies during the early years of CLIVAR is discussed. The discussion is divided geographically into three tropical ocean basins with an emphasis on the dynamical processes that are most relevant to the coupling between the atmosphere and oceans. For the tropical Pacific, the continuing effort to improve understanding of large- and small-scale dynamics for the purpose of extending the skill of ENSO prediction is assessed. This paper then goes beyond the time and space scales of El Niño and discusses recent research activities on the fundamental issue of the processes maintaining the tropical thermocline. This includes the study of subtropical cells (STCs) and ventilated thermocline processes, which are potentially important to the understanding of the low-frequency modulation of El Niño. For the tropical Atlantic, the dominant oceanic processes that interact with regional atmospheric feedbacks are examined as well as the remote influence from both the Pacific El Niño and extratropical climate fluctuations giving rise to multiple patterns of variability distinguished by season and location. The potential impact of Atlantic thermohaline circulation on tropical Atlantic variability (TAV) is also discussed. For the tropical Indian Ocean, local and remote mechanisms governing low-frequency sea surface temperature variations are examined. After reviewing the recent rapid progress in the understanding of coupled dynamics in the region, this study focuses on the active role of ocean dynamics in a seasonally locked east–west internal mode of variability, known as the Indian Ocean dipole (IOD). Influences of the IOD on climatic conditions in Asia, Australia, East Africa, and Europe are discussed. While the attempt throughout is to give a comprehensive overview of what is known about the role of the tropical oceans in climate, the fact of the matter is that much remains to be understood and explained. The complex nature of the tropical coupled phenomena and the interaction among them argue strongly for coordinated and sustained observations, as well as additional careful modeling investigations in order to further advance the current understanding of the role of tropical oceans in climate

Cell distribution after intracoronary bone marrow stem cell delivery in damaged and undamaged myocardium: implications for clinical trials

International audienceABSTRACT : INTRODUCTION : Early randomized clinical trials of autologous bone marrow cardiac stem cell therapy have reported contradictory results highlighting the need for a better evaluation of protocol designs. This study was designed to quantify and compare whole body and heart cell distribution after intracoronary or peripheral intravenous injection of autologous bone marrow mononuclear cells in a porcine acute myocardial infarction model with late reperfusion. METHODS : Myocardial infarction was induced using balloon inflation in the left coronary artery in domestic pigs. At seven days post-myocardial infarction, 1 x 10(8) autologous bone marrow mononuclear cells were labeled with fluorescent marker and/or 99mTc radiotracer, and delivered using intracoronary or peripheral intravenous injection (leg vein). RESULTS : Scintigraphic analyses and Upsilon-emission radioactivity counting of harvested organs showed a significant cell fraction retained within the heart after intracoronary injection (6 +/- 1.7% of injected radioactivity at 24 hours), whereas following peripheral intravenous cell injection, no cardiac homing was observed at 24 hours and cells were mainly detected within the lungs. Importantly, no difference was observed in the percentage of retained cells within the myocardium in the presence or absence of myocardial infarction. Histological evaluation did not show arterial occlusion in both animal groups and confirmed the presence of bone marrow mononuclear cells within the injected myocardium area. CONCLUSIONS : Intravenous bone marrow mononuclear cell injection was ineffective to target myocardium. Myocardial cell distribution following intracoronary injection did not depend on myocardial infarction presence, a factor that could be useful for cardiac cell therapy in patients with chronic heart failure of non-ischemic origin or with ischemic myocardium without myocardial infarction

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Annual, seasonal, and interannual variability of air-sea heat fluxes in the Indian Ocean

Author Posting. © American Meteorological Society, 2007. 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 20 (2007): 3190-3209, doi:10.1175/JCLI4163.1.This study investigated the accuracy and physical representation of air–sea surface heat flux estimates for the Indian Ocean on annual, seasonal, and interannual time scales. Six heat flux products were analyzed, including the newly developed latent and sensible heat fluxes from the Objectively Analyzed Air–Sea Heat Fluxes (OAFlux) project and net shortwave and longwave radiation results from the International Satellite Cloud Climatology Project (ISCCP), the heat flux analysis from the Southampton Oceanography Centre (SOC), the National Centers for Environmental Prediction reanalysis 1 (NCEP1) and reanalysis-2 (NCEP2) datasets, and the European Centre for Medium-Range Weather Forecasts operational (ECMWF-OP) and 40-yr Re-Analysis (ERA-40) products. This paper presents the analysis of the six products in depicting the mean, the seasonal cycle, and the interannual variability of the net heat flux into the ocean. Two time series of in situ flux measurements, one taken from a 1-yr Arabian Sea Experiment field program and the other from a 1-month Joint Air–Sea Monsoon Interaction Experiment (JASMINE) field program in the Bay of Bengal were used to evaluate the statistical properties of the flux products over the measurement periods. The consistency between the six products on seasonal and interannual time scales was investigated using a standard deviation analysis and a physically based correlation analysis. The study has three findings. First of all, large differences exist in the mean value of the six heat flux products. Part of the differences may be attributable to the bias in the numerical weather prediction (NWP) models that underestimates the net heat flux into the Indian Ocean. Along the JASMINE ship tracks, the four NWP modeled mean fluxes all have a sign opposite to the observations, with NCEP1 being underestimated by 53 W m−2 (the least biased) and ECMWF-OP by 108 W m−2 (the most biased). At the Arabian Sea buoy site, the NWP mean fluxes also have an underestimation bias, with the smallest bias of 26 W m−2 (ERA-40) and the largest bias of 69 W m−2 (NCEP1). On the other hand, the OAFlux+ISCCP has the best comparison at both measurement sites. Second, the bias effect changes with the time scale. Despite the fact that the mean is biased significantly, there is no major bias in the seasonal cycle of all the products except for ECMWF-OP. The latter does not have a fixed mean due to the frequent updates of the model platform. Finally, among the four products (OAFlux+ISCCP, ERA-40, NCEP1, and NCEP2) that can be used for studying interannual variability, OAFlux+ISCCP and ERA-40 Qnet have good consistency as judged from both statistical and physical measures. NCEP1 shows broad agreement with the two products, with varying details. By comparison, NCEP2 is the least representative of the Qnet variabilities over the basin scale.This work is supported by the NOAA Office of Climate Observation and the Office of Climate Change and Data Detection under Grant NA17RJ1223

Westerly wind bursts : ENSO’s tail rather than the dog?

Author Posting. © American Meteorological Society, 2005. 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 18 (2005): 5224–5238, doi:10.1175/JCLI3588.1.Westerly wind bursts (WWBs) in the equatorial Pacific occur during the development of most El Niño events and are believed to be a major factor in ENSO's dynamics. Because of their short time scale, WWBs are normally considered part of a stochastic forcing of ENSO, completely external to the interannual ENSO variability. Recent observational studies, however, suggest that the occurrence and characteristics of WWBs may depend to some extent on the state of ENSO components, implying that WWBs, which force ENSO, are modulated by ENSO itself. Satellite and in situ observations are used here to show that WWBs are significantly more likely to occur when the warm pool is extended eastward. Based on these observations, WWBs are added to an intermediate complexity coupled ocean-atmosphere ENSO model. The representation of WWBs is idealized such that their occurrence is modulated by the warm pool extent. The resulting model run is compared with a run in which the WWBs are stochastically applied. The modulation of WWBs by ENSO results in an enhancement of the slow frequency component of the WWBs. This causes the amplitude of ENSO events forced by modulated WWBs to be twice as large as the amplitude of ENSO events forced by stochastic WWBs with the same amplitude and average frequency. Based on this result, it is suggested that the modulation of WWBs by the equatorial Pacific SST is a critical element of ENSO's dynamics, and that WWBs should not be regarded as purely stochastic forcing. In the paradigm proposed here, WWBs are still an important aspect of ENSO's dynamics, but they are treated as being partially stochastic and partially affected by the large-scale ENSO dynamics, rather than being completely external to ENSO. It is further shown that WWB modulation by the large-scale equatorial SST field is roughly equivalent to an increase in the ocean-atmosphere coupling strength, making the coupled equatorial Pacific effectively self-sustained.IE and ET are supported by the US National Science Foundation Climate Dynamics program grant ATM-0351123. LY is supported by NASA ocean vector wind science team under JPL contract 1216955 and NSF Climate Dynamics grant ATM-0350266