7 results on '"Muñoz-Sabater, Joaquín"'
Search Results
2. The ERA5 global reanalysis: Preliminary extension to 1950.
- Author
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Bell, Bill, Hersbach, Hans, Simmons, Adrian, Berrisford, Paul, Dahlgren, Per, Horányi, András, Muñoz-Sabater, Joaquín, Nicolas, Julien, Radu, Raluca, Schepers, Dinand, Soci, Cornel, Villaume, Sebastien, Bidlot, Jean-Raymond, Haimberger, Leo, Woollen, Jack, Buontempo, Carlo, and Thépaut, Jean-Noël
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UPPER air temperature ,QUASI-biennial oscillation (Meteorology) ,PRECIPITATION variability ,OCEAN conditions (Weather) ,VOLCANIC eruptions ,TROPICAL cyclones - Abstract
The extension of the ERA5 reanalysis back to 1950 supplements the previously published segment covering 1979 to the present. It features the assimilation of additional conventional observations, as well as improved use of early satellite data. The number of observations assimilated increases from 53,000 per day in early 1950 to 570,000 per day by the end of 1978. Accordingly, the quality of the reanalysis improves throughout the period, generally joining seamlessly with the segment covering 1979 to the present. The fidelity of the extension is illustrated by the accurate depiction of the North Sea storm of 1953, and the events leading to the first discovery of sudden stratospheric warmings in 1952. Time series of ERA5 global surface temperature anomalies show temperatures to be relatively stable from 1950 until the late 1970s, in agreement with the other contemporary full-input reanalysis covering this period and with independent data sets, although there are significant differences in the accuracy of representing specific regions, Europe being well represented in the early period but Australia less so. The variability of ERA5 precipitation from month to month agrees well with observations for all continents, with correlations above 90% for most of Europe and generally in excess of 70% for North America, Asia and Australia. The evolution of upper air temperatures, humidities and winds shows smoothly varying behaviour, including tropospheric warming and stratospheric cooling, modulated by volcanic eruptions. The Quasi-Biennial Oscillation is well represented throughout. Aspects to be improved upon in future reanalyses include the assimilation of tropical cyclone data, the spin-up of soil moisture and stratospheric humidity, and the representation of surface temperatures over Australia. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
3. The ERA5 global reanalysis.
- Author
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Hersbach, Hans, Bell, Bill, Berrisford, Paul, Hirahara, Shoji, Horányi, András, Muñoz‐Sabater, Joaquín, Nicolas, Julien, Peubey, Carole, Radu, Raluca, Schepers, Dinand, Simmons, Adrian, Soci, Cornel, Abdalla, Saleh, Abellan, Xavier, Balsamo, Gianpaolo, Bechtold, Peter, Biavati, Gionata, Bidlot, Jean, Bonavita, Massimo, and Chiara, Giovanna
- Subjects
OCEAN waves ,CLIMATE change ,STRATOSPHERE ,TROPOSPHERE - Abstract
Within the Copernicus Climate Change Service (C3S), ECMWF is producing the ERA5 reanalysis which, once completed, will embody a detailed record of the global atmosphere, land surface and ocean waves from 1950 onwards. This new reanalysis replaces the ERA‐Interim reanalysis (spanning 1979 onwards) which was started in 2006. ERA5 is based on the Integrated Forecasting System (IFS) Cy41r2 which was operational in 2016. ERA5 thus benefits from a decade of developments in model physics, core dynamics and data assimilation. In addition to a significantly enhanced horizontal resolution of 31 km, compared to 80 km for ERA‐Interim, ERA5 has hourly output throughout, and an uncertainty estimate from an ensemble (3‐hourly at half the horizontal resolution). This paper describes the general set‐up of ERA5, as well as a basic evaluation of characteristics and performance, with a focus on the dataset from 1979 onwards which is currently publicly available. Re‐forecasts from ERA5 analyses show a gain of up to one day in skill with respect to ERA‐Interim. Comparison with radiosonde and PILOT data prior to assimilation shows an improved fit for temperature, wind and humidity in the troposphere, but not the stratosphere. A comparison with independent buoy data shows a much improved fit for ocean wave height. The uncertainty estimate reflects the evolution of the observing systems used in ERA5. The enhanced temporal and spatial resolution allows for a detailed evolution of weather systems. For precipitation, global‐mean correlation with monthly‐mean GPCP data is increased from 67% to 77%. In general, low‐frequency variability is found to be well represented and from 10 hPa downwards general patterns of anomalies in temperature match those from the ERA‐Interim, MERRA‐2 and JRA‐55 reanalyses. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
4. Assimilation de données de télédétection pour le suivi des surfaces continentales : Mise en oeuvre sur un site expérimental
- Author
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Muñoz Sabater, Joaquín, Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Paul Sabatier - Toulouse III, Jean-Christophe Calvet, Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), and Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS)
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remote sensing ,télédétection ,vegetation biomass ,humidité du sol ,biomasse de la végétation ,soil moisture ,assimilation de données ,[SDU.OTHER]Sciences of the Universe [physics]/Other ,data assimilation - Abstract
The research undertaken in this thesis focuses on the assimilation of remotely sensed data for continental surface monitoring. The analysed variables are root-zone soil moisture content and above-ground vegetation biomass. The data cover the period 2001 to 2004 and were collected over fallow at the SMOSREX experimental site, south-west of Toulouse, France. Four assimilation techniques (EKF, EnKF, 1D-VAR and T-VAR) were implemented into the Météo-France SVAT model ISBA-A-gs and their performances compared to each other. It was found that the 1D-VAR is the most effective technique, for both quality of the analyses and lower computational cost. This particular technique was applied in a joint assimilation of surface soil moisture and leaf are index observations, as well as of remotely sensed measurements collected over the site. The assimilation improves the control simulation, if a dynamic wilting point is introduced (this is particularly useful during strong drought periods). The impact of a high level of uncertainty in the precipitation data is also evaluated.; Le travail réalisé dans le cadre de cette thèse porte sur l'assimilation de données de télédétection pour le suivi des surfaces continentales. Les variables analysées sont l'état hydrique du sol et la biomasse de la végétation, sur la jachère du site expérimental SMOSREX, de 2001 à 2004, au sud-ouest de Toulouse. Quatre méthodes d'assimilation (EKF, EnKF, 1D-VAR et T-VAR) ont été mises en œuvre dans le modèle ISBA-A-gs de Météo-France, et comparées. La méthode 1D-VAR est la plus performante, aussi bien pour la qualité des analyses qu'en temps de calcul. Cette méthode a été appliquée à l'assimilation simultanée des observations de l'humidité de la surface et de l'indice foliaire, ainsi qu'aux mesures de télédétection réalisées sur le site. L'assimilation améliore la simulation de contrôle, à condition d'introduire un point de flétrissement dynamique (cela est particulièrement utile pendant les périodes de forte sécheresse). Les effets d'une incertitude sur les précipitations sont évalués.
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- 2007
5. SMOS Brightness Temperature Angular Noise: Characterization, Filtering, and Validation.
- Author
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Muñoz-Sabater, Joaquín, de Rosnay, Patricia, Jiménez, Carlos, Isaksen, Lars, and Albergel, Clément
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BRIGHTNESS temperature measurement , *INTERFEROMETRY , *ARTIFICIAL satellites , *MICROWAVE measurements , *RADIOMETERS - Abstract
The 2-D interferometric radiometer on board the Soil Moisture and Ocean Salinity (SMOS) satellite has been providing a continuous data set of brightness temperatures, at different viewing geometries, containing information of the Earth's surface microwave emission. This data set is affected by several sources of noise, which are a combination of the noise associated with the radiometer itself and the different views under which a heterogeneous target, such as continental surfaces, is observed. As a result, the SMOS data set is affected by a significant amount of noise. For many applications, such as soil moisture retrieval, reducing noise from the observations while keeping the signal is necessary, and the accuracy of the retrievals depends on the quality of the observed data set. This paper investigates the averaging of SMOS brightness temperatures in angular bins of different sizes as a simple method to reduce noise. All the observations belonging to a single pixel and satellite overpass were fitted to a polynomial regression model, with the objective of characterizing and evaluating the associated noise. Then, the observations were averaged in angular bins of different sizes, and the potential benefit of this process to reduce noise from the data was quantified. It was found that, if a 2° angular bin is used to average the data, the noise is reduced by up to 3 K. Furthermore, this method complements necessary data thinning approaches when a large volume of data is used in data assimilation systems. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
- View/download PDF
6. Initialisation of Land Surface Variables for Numerical Weather Prediction.
- Author
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Rosnay, Patricia, Balsamo, Gianpaolo, Albergel, Clément, Muñoz-Sabater, Joaquín, and Isaksen, Lars
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Land surface processes and their initialisation are of crucial importance for Numerical Weather Prediction (NWP). Current land data assimilation systems used to initialise NWP models include snow depth analysis, soil moisture analysis, soil temperature and snow temperature analysis. This paper gives a review of different approaches used in NWP to initialise land surface variables. It discusses the observation availability and quality, and it addresses the combined use of conventional observations and satellite data. Based on results from the European Centre for Medium-Range Weather Forecasts (ECMWF), results from different soil moisture and snow depth data assimilation schemes are shown. Both surface fields and low-level atmospheric variables are highly sensitive to the soil moisture and snow initialisation methods. Recent developments of ECMWF in soil moisture and snow data assimilation improved surface and atmospheric forecast performance. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
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7. Sensitivity of Soil Moisture Analyses to Contrasting Background and Observation Error Scenarios.
- Author
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Muñoz-Sabater, Joaquín, de Rosnay, Patricia, Albergel, Clément, and Isaksen, Lars
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SOIL moisture ,WEATHER forecasting ,SEAWATER salinity ,ATMOSPHERIC temperature ,HUMIDITY - Abstract
Soil moisture is a crucial variable for numerical weather prediction. Accurate, global initialization of soil moisture is obtained through data assimilation systems. However, analyses depend largely on the way observation and background errors are defined. In this study, a wide range of short experiments with contrasted specifications of the observation error and soil moisture background were conducted. As observations, screen-level variables and brightness temperatures from the Soil Moisture and Ocean Salinity (SMOS) mission were used. The region of interest is North America, given the good availability of in situ observations and mixture of different climates, making it a good test for global applications. The impact of these experiments on soil moisture and the atmospheric layer near the surface were evaluated. The results highlighted the importance of assimilating observations sensitive to soil moisture for air temperature and humidity forecasts. The benefits on predicting the soil water content were more noticeable with increasing the SMOS observation error, and with the introduction of soil texture dependency in the soil moisture background error. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
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