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Atmospheric angular momentum related to Earth rotation studies: history and modern developments / David A. Salstein (2019) 

Public Titre : Atmospheric angular momentum related to Earth rotation studies: history and modern developments Type de document : Article/Communication Auteurs : David A. Salstein, Auteur Editeur : Paris, Meudon et Nançay : Observatoire de Paris Année de publication : 2019 Conférence : JSRST 2019, Journées systèmes de référence spatio-temporels, Astrometry, Earth Rotation, and Reference Systems in the GAIA era 07/10/2019 09/10/2019 Paris France OA Proceedings Importance : pp 209 - 213 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie [Termes IGN] moment cinétique atmosphérique [Termes IGN] rotation de la Terre Résumé : (auteur) It was noted some time ago that the angular momentum of the atmosphere varies, both regionally as well as in total. Given the conservation of angular momentum in the Earth system, except for known external torques, such variability implies transfer of the angular momentum across the atmosphere’s lower boundary. As nearly all is absorbed by the Earth below, the solid Earth changes its overall rotation from this impact. Due to the large difference between in the moments of inertia of the atmosphere and Earth, relatively big differences in the atmosphere are translated as relatively very small differences in the Earth, measurable as changes in Earth rotation rate, and polar motion. The atmospheric angular momentum (AAM) is that due to the motion of the winds and to the changes in mass distribution, closely related to the atmosphere pressure patterns; its variability in the atmosphere is mirrored in the Earth rotation rate and polar motion. This connection between the global solid Earth properties and the global and regional atmosphere on a number of time scales, especially seasonal and interannual, was much appreciated by Barbara Kolaczek, with Jolanta Nastula, at the Space Research Center in Warsaw, and this was a subject of our collaborative studies. Many calculations were made of atmospheric angular momentum, leading to a service under the Global Geophysical Fluids Center of the IERS based on calculations using both operational meteorological series, determined for weather forecasting purposes, and retrospective analyses of the atmosphere. Theoretical development of the connection between the AAM, Earth rotation/polar motion, and also the angular momentum of the other geophysical fluids occurred at the same time that space-based observations and enhanced computer power were allowing improved skills for both weather analysis and forecasting. Hence better determination of the AAM became possible, which could be used as a measure for forecasting Earth rotation. Today we are looking at the atmosphere in combination with the ocean and other fluids, and also assessing the implications of climate variability on Earth rotation through climate model research. According to models of the Earth system, significant changes in winds appear to be a possible result of climate change, with implications for the Earth rotation parameters. Numéro de notice : C2019-076 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Communication DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100193

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Hydrological excitation of polar motion by different variables from the GLDAS models / Malgorzata Winska in Journal of geodesy, vol 91 n° 12 (December 2017)  

Public [article]  inJournal of geodesy > vol 91 n° 12 (December 2017) . - pp 1461 - 1473 Titre : Hydrological excitation of polar motion by different variables from the GLDAS models Type de document : Article/Communication Auteurs : Malgorzata Winska, Auteur ; Jolanta Nastula, Auteur ; David A. Salstein, Auteur Année de publication : 2017 Article en page(s) : pp 1461 - 1473 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] données GRACE [Termes IGN] moment cinétique [Termes IGN] mouvement du pôle [Termes IGN] surcharge hydrologique Mots-clés libres : Global Land Data Assimilation System model  GLDAS model Résumé : (Auteur) Continental hydrological loading by land water, snow and ice is a process that is important for the full understanding of the excitation of polar motion. In this study, we compute different estimations of hydrological excitation functions of polar motion (as hydrological angular momentum, HAM) using various variables from the Global Land Data Assimilation System (GLDAS) models of the land-based hydrosphere. The main aim of this study is to show the influence of variables from different hydrological processes including evapotranspiration, runoff, snowmelt and soil moisture, on polar motion excitations at annual and short-term timescales. Hydrological excitation functions of polar motion are determined using selected variables of these GLDAS realizations. Furthermore, we use time-variable gravity field solutions from the Gravity Recovery and Climate Experiment (GRACE) to determine the hydrological mass effects on polar motion excitation. We first conduct an intercomparison of the maps of variations of regional hydrological excitation functions, timing and phase diagrams of different regional and global HAMs. Next, we estimate the hydrological signal in geodetically observed polar motion excitation as a residual by subtracting the contributions of atmospheric angular momentum and oceanic angular momentum. Finally, the hydrological excitations are compared with those hydrological signals determined from residuals of the observed polar motion excitation series. The results will help us understand the relative importance of polar motion excitation within the individual hydrological processes, based on hydrological modeling. This method will allow us to estimate how well the polar motion excitation budget in the seasonal and inter-annual spectral ranges can be closed. Numéro de notice : A2017-708 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-017-1036-8 En ligne : https://doi.org/10.1007/s00190-017-1036-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=88089 [article]

High-resolution atmospheric angular momentum functions related to Earth rotation parameters during CONT08 / D. Gambis in Journal of geodesy, vol 85 n° 7 (July 2011)  

Public [article]  inJournal of geodesy > vol 85 n° 7 (July 2011) . - pp 435 - 441 Titre : High-resolution atmospheric angular momentum functions related to Earth rotation parameters during CONT08 Type de document : Article/Communication Auteurs : D. Gambis, Auteur ; David A. Salstein, Auteur ; S. Lambert, Auteur Année de publication : 2011 Article en page(s) : pp 435 - 441 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] analyse comparative [Termes IGN] données GPS [Termes IGN] données ITGB [Termes IGN] moment cinétique atmosphérique [Termes IGN] rotation de la Terre Résumé : (Auteur) Due to the temporal resolution of available numerical weather analyses, the effect of the atmosphere on Earth rotation at daily and sub-daily periods is usually investigated using 6-hourly atmospheric angular momentum (AAM) functions. During the period of CONT08, however, atmospheric analysis data were provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) also on an hourly basis. In this paper, we, therefore, determine two sets of AAM functions from ECMWF data—one for CONT08 with hourly resolution and one for the year 2008 with 6-hourly resolution. The comparisons of the AAM functions to high-resolution Earth rotation parameters (ERP) from VLBI and GPS observations are carried out in the frequency domain. Special attention is paid to the preparation of the high-resolution data sets for the geodetic purposes, as there are jump discontinuities at 12 h intervals. Hence, the hourly AAM functions need to be concatenated. The revised functions yield much smaller amplitudes than their 6-hourly counterparts, as can be seen from the equatorial and the axial frequency spectra of atmospheric excitation in Earth rotation. This decrease of spectral power in the hourly AAM functions is found to be associated with a strong counteraction of pressure and wind terms, which originates from atmospheric circulation on short time scales. The results are compared to previous findings published by Brzezin'ski and Petrov (IERS Tech Note 28:53–60, 2000) based on the data from the U.S. National Centers for Environmental Prediction (NCEP). Numéro de notice : A2011-332 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0458-y Date de publication en ligne : 27/04/2011 En ligne : https://doi.org/10.1007/s00190-011-0458-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31111 [article]

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vol 85 n° 7 - July 2011 - CONT08 -continuous geodetic VLBI campaign 2008 August 12-26 2008 (Bulletin de Journal of geodesy) / Axel Nothnagel  

Public [n° ou bulletin]  est un bulletin de Journal of geodesy (1996 -)   Titre : vol 85 n° 7 - July 2011 - CONT08 -continuous geodetic VLBI campaign 2008 August 12-26 2008 Type de document : Périodique Auteurs : Axel Nothnagel, Éditeur scientifique ; U. Hungentobler, Éditeur scientifique ; International association of geodesy, Auteur ; David A. Salstein, Éditeur scientifique Année de publication : 2011 Importance : 50 p. Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes IGN] dégradation du signal [Termes IGN] interférométrie à très grande base [Termes IGN] troposphère Numéro de notice : 266-201107 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Numéro de périodique En ligne : http://link.springer.com/journal/190/85/7/page/1 Format de la ressource électronique : URL sommaire Permalink : https://documentation.ensg.eu/index.php?lvl=bulletin_display&id=16338 [n° ou bulletin]

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• VLBI-derived troposphere parameters during CONT08 / Robert Heinkelmann in Journal of geodesy, vol 85 n° 7 (July 2011)  
• Multi-technique comparison of troposphere zenith delays and gradients during CONT08 / Kamil Teke in Journal of geodesy, vol 85 n° 7 (July 2011)  
• High-resolution atmospheric angular momentum functions related to Earth rotation parameters during CONT08 / D. Gambis in Journal of geodesy, vol 85 n° 7 (July 2011)  

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The impact of El Nino and other low-frequency signals on Earth rotation and global Earth systems parameters / David A. Salstein (1999)

Public Titre : The impact of El Nino and other low-frequency signals on Earth rotation and global Earth systems parameters Type de document : Monographie Auteurs : David A. Salstein, Éditeur scientifique ; B. Kolaczek, Éditeur scientifique ; D. Gambis, Éditeur scientifique Editeur : Paris, Meudon et Nançay : Observatoire de Paris Année de publication : 1999 Collection : IERS Technical note num. 26 Importance : 74 p. Format : 21 x 30 cm Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] altimétrie [Termes IGN] atmosphère terrestre [Termes IGN] interférométrie à très grande base [Termes IGN] International Terrestrial Reference Frame [Termes IGN] rotation de la Terre Numéro de notice : 18920 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Recueil / ouvrage collectif Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=41580

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