87,118 research outputs found
Two-dimensional reconstruction of the Mediterranean sea level over 1970 - 2006 from tide gauge data and regional ocean circulation model outputs
No full textwo-dimensional reconstructions of the Mediterranean sea level corrected for the atmospheric effects are proposed at monthly interval over the period 1970-2006 using 14 tide gage records and 33-year long (1970-2002) sea level grids from the NEMOMED8 regional ocean circulation model (NM8) and the PROTHEUS System Atmosphere-Ocean coupled model (PS). They are compared with a similar reconstruction using decade-long sea level grids from altimetry (Topex/Poseidon and Jason1) and a published reconstruction by Calafat and Gomis (2009). Tests with extra tide gages, not used in the computation, show that interannual variability is better captured when using long (33-year) spatial grids. In particular the NM8-based reconstruction reproduces better the sea level variability at all independent tide gages. An empirical Orthogonal Function decomposition of this reconstruction over 1970-2006 shows that the temporal curve of the two first modes are highly correlated with the North Atlantic Oscillation. We note in particular different behaviors over the 1970-1994 and 1994-2006 time spans. Results suggest that the North Atlantic Oscillation forcing modified the spatial patterns of the Mediterranean sea level around the year 1993 close to the date of occurrence of the Eastern Mediterranean Transient (a major change in the deep water formation of the Levantine and Ionian basin that occurred in the early 1990s)
Reconstruction of Mediterranean sea level fields for the period 1945–2000
No full textThe distribution of sea level in the Mediterranean Sea is recovered for the period 1945–2000 by using a reduced space optimal interpolation analysis. The method involves estimating empirical orthogonal functions from satellite altimeter data spanning the period 1993–2005 that are then combined with tide gauge data to recover sea level fields over the period 1945–2000. The reconstruction technique is discussed and its robustness is checked through different tests. For the altimetric period (1993–2000) the prediction skill is quantified over the whole domain by comparing the reconstructed fields with satellite altimeter observations. For past times the skill can only be tested locally, by validating the reconstruction against independent tide gauge records. The reconstructed distribution of sea level trends for the period 1945–2000 shows a positive peak in the Ionian Sea (up to 1.5 mm yr? 1) and a negative peak of ? 0.5 mm yr? 1 in a small area to the south-east of Crete. Positive trends are found nearly everywhere, being larger in the western Mediterranean (between 0.5 and 1 mm yr? 1) than in the eastern Mediterranean (between 0 and 0.5 mm yr? 1). The estimated rate of mean sea level rise for the period 1945–2000 is 0.7 ± 0.2 mm yr? 1, i.e. about a half of the rate estimated for global mean sea level. These overall results do not appear to be very sensitive to the distribution of tide gauges. The poorest results are obtained in open-sea regions with intense mesoscale variability not correlated with any tide gauge station, such as the Algerian Basin
A Mediterranean sea level reconstruction (1950–2008) with error budget estimates
No full textReconstructed sea level fields are commonly obtained by using techniques that combine long-term records from coastal and island tide gauges with spatial covariance structures determined from recent altimetric observations. In this paper we estimate the error budget of the Mediterranean sea level reconstructions based on a reduced space optimal interpolation. In particular, we characterize the baseline error of the methodology, which is linked to the capacity of tide gauges to capture open sea processes and to the representativity of the selected EOFs. Also, we analyze the impact of the non-stationarity of the EOFs and the uneven tide gauge spatial distribution. Results suggest that the baseline error is the dominant contribution in most areas of the Mediterranean (average value of 2.7 cm). In particular, the error due to the truncation of the EOFs is the largest contribution to the baseline error. The other error sources have a more localized impact, which can be important in certain areas with atypical mesoscale activity. The skills of the reconstruction are more dependent on the length of the period than on the particular years used to compute the EOFs. Redundant tide gauges improve the reconstruction only slightly while a single tide gauge at a critical location improves it significantly. In addition we estimate the total error linked to all sources of uncertainty. Finally, we also present an updated sea level reconstruction which includes several improvements with respect to previous reconstructions. The comparison with independent data shows that this new reconstruction provides better results with respect to previous products
Quantifying recent acceleration in sea level unrelated to internal climate variability
No full textSea level observations suggest that the rate of sea level rise has accelerated during the last 20?years. However, the presence of considerable decadal-scale variability, especially on a regional scale, makes it difficult to assess whether the observed changes are due to natural or anthropogenic causes. Here we use a regression model with atmospheric pressure, wind, and climate indices as independent variables to quantify the contribution of internal climate variability to the sea level at nine tide gauges from around the world for the period 1920–2011. Removing this contribution reveals a statistically significant acceleration (0.022?±?0.015?mm/yr2) between 1952 and 2011, which is unique over the whole period. Furthermore, we have found that the acceleration is increasing over time. This acceleration appears to be the result of increasing greenhouse gas concentrations, along with changes in volcanic forcing and tropospheric aerosol loading
BAYEX: Spatiotemporal Bayesian hierarchical modeling of storm surge extremes with max-stable processes
No full textBAYEX offers spatiotemporal Bayesian hierarchical modeling of storm surge extremes using max-stable and latent processes. As a key feature, BAYEX makes estimates of both the GEV parameters (location, scale and shape) and the annual maxima at any arbitrary location, either gauged or ungauged, while providing realistic uncertainty estimates. Inference in BAYEX is performed using Hamiltonian Monte Carlo as implemented by the Stan probabilistic programming language.This version 1.0 of the code was released to accompany the paper:
Calafat, F. M., and M. Marcos (2020), Probabilistic reanalysis of storm surge extremes in Europe. Proc. Natl. Acad. Sci. U. S. A.
Please cite that paper when using this code
Desarrollo de una metodología para la gestión y control de calidad de cimentaciones para ingenieros de edificación
No full textTrabajo científico técnico. El objetivo del presente proyecto es desarrollar de una forma lo más clara posible, una sistemática de actuación para la verificación de la calidad estructural en la edificación, tanto en fase de proyecto como en fase de ejecución. Para ello, se desarrollan varias de las tipologías constructivas existentes en cimentación, ámbito del presente trabajoDios Calafat, F. (2011). Desarrollo de una metodología para la gestión y control de calidad de cimentaciones para ingenieros de edificación. https://riunet.upv.es/handle/10251/11918.Archivo delegad
Data supporting: "Bayesian diagnosis of climate feedback evolution and forced temperature response"
No full textThis data set supports the paper:
Calafat, F. M., & Cael, B. B. (2023). Bayesian diagnosis of climate feedback evolution and forced temperature response, Geophysical Research Letters, submitted.
Please cite this paper when using this data set.
Data description:
EBM_estimates.nc: this file contains Bayesian estimates from the energy balance model, including estimates of the climate feedback parameter and forced global average temperature change.
EBM_input_data.nc: this file contains all of the data used as input to the Bayesian energy balance model
Comparison of Mediterranean sea level fields for the period 1961–2000 as given by a data reconstruction and a 3D model
No full textTwo Mediterranean sea level distributions spanning the last decades are examined. The first one is a reconstruction of sea level obtained by a reduced-space optimal interpolation applied to tide gauge and altimetry data. The second distribution is obtained from a 3D (baroclinic) regional circulation model. None of the two representations includes the mechanical atmospheric forcing. Results are presented for two different periods: 1993–2000 (for which altimetry data are available) and 1961–2000 (the longest period common to both distributions).The first period is examined as a test period for the model, since the reconstruction is very similar to altimetry observations. The modelled sea level is in fair agreement with the reconstruction in the Western Mediterranean and in the Aegean Sea (except in the early nineties), but in the Ionian Sea the model departs from observations. For the whole period 1961–2000 the main feature is a marked positive trend in the Ionian Sea (up to 1.8 mm yr? 1), observed both in the reconstruction and in the model. Also the distribution of positive trends in the Western Mediterranean (mean value of 1.1 mm yr? 1) and the smaller trends in the Aegean Sea (0.5 mm yr? 1) are similar in the reconstruction and in the model, despite the first implicitly accounts for sea level variations due to remote sources such as ice melting and the second does not. The interannual sea level variability associated with key regional events such as the Eastern Mediterranean Transient is apparently captured by the reconstruction but not by the model (at least in its present configuration). Hence, the reconstruction can be envisaged as a useful tool to validate further long-term numerical simulations in the region
Code supporting: "The Sources of Sea-Level Changes in the Mediterranean Sea since 1960"
No full textThis code supports the paper:
Calafat, F. M., Frederikse, T., and Horsburgh, K. (2022). The Sources of Sea-Level Changes in the Mediterranean Sea since 1960, Journal of Geophysical Research Oceans, under review.
Please cite this paper when using this code.
Overview:
The code implements spatiotemporal Bayesian hierarchical modeling of sea-level observations from tide gauges and satellite altimetry in combination with sea-level fingerprints of contemporary land-mass changes (GRD effects) and glacial isostatic adjustment (GIA). It makes estimates of sea-level changes as well as rates of change and quantifies the individual contribution from sterodynamic changes, GRD effects, and GIA to sea-level changes at any arbitrary location (observed or unobserved). Inference in the model is performed using Hamiltonian Monte Carlo as implemented by the Stan probabilistic programming language.
Input data to run the Bayesian hierarchical model and needed to replicate the results of the paper are available at https://doi.org/10.5281/zenodo.6797928
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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