{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T01:56:12Z","timestamp":1760234172661,"version":"build-2065373602"},"reference-count":61,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2021,4,16]],"date-time":"2021-04-16T00:00:00Z","timestamp":1618531200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"University of Bologna","award":["ECOCZERB"],"award-info":[{"award-number":["ECOCZERB"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Vertical deformations of the Earth\u2019s surface result from a host of geophysical and geological processes. Identification and assessment of the induced signals is key to addressing outstanding scientific questions, such as those related to the role played by the changing climate on height variations. This study, focused on the European and Mediterranean area, analyzed the GPS height time series of 114 well-distributed stations with the aim of identifying spatially coherent signals likely related to variations of environmental parameters, such as atmospheric surface pressure (SP) and terrestrial water storage (TWS). Linear trends and seasonality were removed from all the time series before applying the principal component analysis (PCA) to identify the main patterns of the space\/time interannual variability. Coherent height variations on timescales of about 5 and 10 years were identified by the first and second mode, respectively. They were explained by invoking loading of the crust. Single-value decomposition (SVD) was used to study the coupled interannual space\/time variability between the variable pairs GPS height\u2013SP and GPS height\u2013TWS. A decadal timescale was identified that related height and TWS variations. Features common to the height series and to those of a few climate indices\u2014namely, the Arctic Oscillation (AO), the North Atlantic Oscillation (NAO), the East Atlantic (EA), and the multivariate El Ni\u00f1o Southern Oscillation (ENSO) index (MEI)\u2014were also investigated. We found significant correlations only with the MEI. The first height PCA mode of variability, showing a nearly 5-year fluctuation, was anticorrelated (\u22120.23) with MEI. The second mode, characterized by a decadal fluctuation, was well correlated (+0.58) with MEI; the spatial distribution of the correlation revealed, for Europe and the Mediterranean area, height decrease till 2015, followed by increase, while Scandinavian and Baltic countries showed the opposite behavior.<\/jats:p>","DOI":"10.3390\/rs13081554","type":"journal-article","created":{"date-parts":[[2021,4,19]],"date-time":"2021-04-19T06:35:53Z","timestamp":1618814153000},"page":"1554","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Interannual Variability of GPS Heights and Environmental Parameters over Europe and the Mediterranean Area"],"prefix":"10.3390","volume":"13","author":[{"given":"Letizia","family":"Elia","sequence":"first","affiliation":[{"name":"Dipartimento di Fisica e Astronomia (DIFA), University of Bologna, 40126 Bologna, Italy"}]},{"given":"Susanna","family":"Zerbini","sequence":"additional","affiliation":[{"name":"Dipartimento di Fisica e Astronomia (DIFA), University of Bologna, 40126 Bologna, Italy"}]},{"given":"Fabio","family":"Raicich","sequence":"additional","affiliation":[{"name":"CNR\u2014Istituto di Scienze Marine, 34123 Trieste, Italy"}]}],"member":"1968","published-online":{"date-parts":[[2021,4,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.tecto.2009.08.018","article-title":"The geology of vertical movements of the lithosphere: An overview","volume":"475","author":"Teixell","year":"2009","journal-title":"Tectonophysics"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2342","DOI":"10.1126\/science.1065328","article-title":"A New Global Mode of Earth Deformation: Seasonal Cycle Detected","volume":"294","author":"Blewitt","year":"2001","journal-title":"Science"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"ETG 9-1","DOI":"10.1029\/2001JB000570","article-title":"Effect of annual signals on geodetic velocity","volume":"107","author":"Blewitt","year":"2002","journal-title":"J. Geophys. Res. Solid Earth"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"ETG 4-1","DOI":"10.1029\/2002JB002297","article-title":"Correction to \u201cEffect of annual signals on geodetic velocity\u201d by Geoffrey Blewitt and David Lavall\u00e9e","volume":"108","author":"Blewitt","year":"2003","journal-title":"J. Geophys. Res. Solid Earth"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"761","DOI":"10.1029\/RG010i003p00761","article-title":"Deformation of the Earth by surface loads","volume":"10","author":"Farrell","year":"1972","journal-title":"Rev. Geophys."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1077","DOI":"10.1016\/S0079-1946(98)00147-5","article-title":"Modeling environment loading effects: A review","volume":"23","author":"Wahr","year":"1998","journal-title":"Phys. Chem. Earth"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"651","DOI":"10.1007\/978-3-642-10634-7_86","article-title":"Modeling and Observation of Loading Contribution to Time-Variable GPS Sites Positions","volume":"Volume 135","author":"Mertikas","year":"2010","journal-title":"Gravity, Geoid and Earth Observation"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"B03405","DOI":"10.1029\/2003JB002500","article-title":"Study of the atmospheric pressure loading signal in very long baseline interferometry observations","volume":"109","author":"Petrov","year":"2004","journal-title":"J. Geophys. Res. Solid Earth"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"L22310","DOI":"10.1029\/2005GL024104","article-title":"Atmospheric pressure loading corrections applied to GPS data at the observation level","volume":"32","author":"Tregoning","year":"2005","journal-title":"Geophys. Res. Lett."},{"key":"ref_10","unstructured":"Maggioni, V., and Massari, C. (2019). Chapter Two\u2014Terrestrial water storage. Extreme Hydroclimatic Events and Multivariate Hazards in a Changing Environment, Elsevier."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"651","DOI":"10.1029\/2000GL012120","article-title":"Crustal displacements due to continental water loading","volume":"28","author":"Wahr","year":"2001","journal-title":"Geophys. Res. Lett."},{"key":"ref_12","first-page":"134","article-title":"Earth Deformation Effects Modelling","volume":"Volume 1","author":"Fletcher","year":"2013","journal-title":"GNSS Data Processing, Vol. I: Fundamentals and Algorithms"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"L23609","DOI":"10.1029\/2004GL021185","article-title":"Observing and assessing nontidal ocean loading using ocean, continuous GPS and gravity data in the Adriatic area","volume":"31","author":"Zerbini","year":"2004","journal-title":"Geophys. Res. Lett."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1043","DOI":"10.1007\/s00190-012-0564-5","article-title":"Nontidal ocean loading: Amplitudes and potential effects in GPS height time series","volume":"86","author":"Collilieux","year":"2012","journal-title":"J. Geod."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"45","DOI":"10.1007\/s10291-020-0959-3","article-title":"Correcting GPS measurements for non-tidal loading","volume":"24","author":"Boy","year":"2020","journal-title":"GPS Solut."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Wu, S., Nie, G., Meng, X., Liu, J., He, Y., Xue, C., and Li, H. (2020). Comparative Analysis of the Effect of the Loading Series from GFZ and EOST on Long-Term GPS Height Time Series. Remote Sens., 12.","DOI":"10.3390\/rs12172822"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"57","DOI":"10.2478\/arsa-2019-0006","article-title":"Influence of Geophysical signals on coordinate variations GNSS permanent stations in central Europe","volume":"54","author":"Kaczmarek","year":"2019","journal-title":"Artif. Satell."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"42","DOI":"10.1007\/s00190-020-01370-y","article-title":"Comparative analysis of different atmospheric surface pressure models and their impacts on daily ITRF2014 GNSS residual time series","volume":"94","author":"Li","year":"2020","journal-title":"J. Geod."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"74","DOI":"10.1016\/j.earscirev.2011.10.004","article-title":"Present-day trends of vertical ground motion along the coast lines","volume":"110","author":"Ostanciaux","year":"2012","journal-title":"Earth Sci. Rev."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"2145","DOI":"10.1007\/s00190-019-01295-1","article-title":"Evidence of daily hydrological loading in GPS time series over Europe","volume":"93","author":"Springer","year":"2019","journal-title":"J. Geod."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"74","DOI":"10.1016\/j.pepi.2014.03.002","article-title":"Hydrological changes and vertical crustal deformation in south India: Inference from GRACE, GPS and absolute gravity data","volume":"231","author":"Tiwari","year":"2014","journal-title":"Phys. Earth Planet. Int."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1139","DOI":"10.1007\/s10712-016-9385-z","article-title":"Terrestrial Water Storage Anomalies Associated with Drought in Southwestern USA from GPS Observations","volume":"37","author":"Jin","year":"2016","journal-title":"Surv. Geophys."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"13006","DOI":"10.1029\/2019GL085370","article-title":"A decade of Water Storage Changes across the Contiguous United States from GPS and Satellite Gravity","volume":"46","author":"Adusumilli","year":"2019","journal-title":"Geophys. Res. Lett."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"743","DOI":"10.1002\/2014GL062446","article-title":"Climate-driven vertical acceleration of Icelandic crust measured by continuous GPS geodesy","volume":"42","author":"Compton","year":"2015","journal-title":"Geophys. Res. Lett."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"111","DOI":"10.1016\/j.jog.2012.04.006","article-title":"An EOF and SVD analysis of interannual variability of GPS coordinates, environmental parameters and space gravity data","volume":"67","author":"Zerbini","year":"2013","journal-title":"J. Geodyn."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Blewitt, G., Hammond, W.C., and Kreemer, C. (2018). Harnessing the GPS Data Explosion for Interdisciplinary Science. Eos, 99.","DOI":"10.1029\/2018EO104623"},{"key":"ref_27","unstructured":"SOPAC (2020, June 18). The Scripps Orbit and Permanent Array Center. Available online: http:\/\/sopac.ucsd.edu\/."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1203","DOI":"10.1007\/s00190-014-0754-4","article-title":"Detecting discontinuities in GNSS coordinate time series with STARS: Case study, the Bologna and Medicina GPS sites","volume":"88","author":"Bruni","year":"2014","journal-title":"J. Geod."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"437","DOI":"10.1175\/1520-0477(1996)077<0437:TNYRP>2.0.CO;2","article-title":"The NCEP\/NCAR 40-year reanalysis project","volume":"77","author":"Kalnay","year":"1996","journal-title":"Bull. Amer. Meteor. Soc."},{"key":"ref_30","unstructured":"Global Modeling and Assimilation Office (GMAO) (2020, September 30). MERRA-2 tavg1_2d_lnd_Nx: 2d,1-Hourly, Time-Averaged, Single-Level, Assimilation, Land Surface Diagnostics V5.12.4, Greenbelt, MD, USA, Goddard Earth Sciences Data and Information Services Center (GES DISC), 2015. Available online: https:\/\/arcticdata.io\/catalog\/view\/doi%3A10.18739%2FA27M0416J."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"20150202","DOI":"10.1098\/rsta.2015.0202","article-title":"Principal component analysis: A review and recent developments","volume":"374","author":"Jolliffe","year":"2016","journal-title":"Phil. Trans. R. Soc. A"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"735","DOI":"10.1109\/TCS.1975.1084118","article-title":"A new algorithm in spectral analysis and band-limited extrapolation","volume":"22","author":"Papoulis","year":"1975","journal-title":"IEEE Trans. Circuits Syst."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"709","DOI":"10.1080\/713818946","article-title":"Super-resolution through error energy reduction","volume":"21","author":"Gerchberg","year":"1974","journal-title":"Opt. Acta"},{"key":"ref_34","first-page":"626","article-title":"EM algorithms for PCA and SPCA","volume":"Volume 10","author":"Roweis","year":"1998","journal-title":"Advances in Neural Information Processing Systems"},{"key":"ref_35","first-page":"112","article-title":"A Manual for EOF and SVD Analyses of Climatic Data","volume":"97","author":"Venegas","year":"1997","journal-title":"McGill Univ. Rep. N"},{"key":"ref_36","unstructured":"(2020, January 22). GCOS. Available online: https:\/\/gcos.wmo.int\/en\/essential-climate-variables."},{"key":"ref_37","unstructured":"WMO (2012). Statement on the State of the Global Climate in 2011, World Meteorological Organization. Available online: https:\/\/library.wmo.int\/index.php?lvl=notice_display&id=9754#.YBLB9-hKhjk."},{"key":"ref_38","unstructured":"Bissolli, P., Ziese, M., Pietzsch, S., Finger, P., Friedrich, K., Nitsche, H., and Obreg\u00f3n, A. (2012). Drought conditions in Europe in the spring of 2012. Dtsch. Wetterd., Available online: https:\/\/www.dwd.de\/EN\/ourservices\/specialevents\/drought\/20120810_Trockenheit_2012_en.pdf?_blob=publicationFile&v=4."},{"key":"ref_39","unstructured":"WMO (2014). Statement on the State of the Global Climate in 2013, World Meteorological Organization. Available online: https:\/\/library.wmo.int\/index.php?lvl=notice_display&id=15957#.YBLBq-hKhjk."},{"key":"ref_40","unstructured":"WMO (2015). Statement on the State of the Global Climate in 2014, World Meteorological Organization. Available online: https:\/\/library.wmo.int\/index.php?lvl=notice_display&id=16898#.YBLVeehKhjk."},{"key":"ref_41","unstructured":"WMO (2016). Statement on the State of the Global Climate in 2015, World Meteorological Organization. Available online: https:\/\/library.wmo.int\/index.php?lvl=notice_display&id=19125#.YBLDkOhKhjk."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"1397","DOI":"10.5194\/hess-21-1397-2017","article-title":"The European 2015 drought from a climatological perspective","volume":"21","author":"Ionita","year":"2017","journal-title":"Hydrol. Earth Syst. Sci."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"3169","DOI":"10.1175\/JCLI-D-18-0331.1","article-title":"The European 2016\/17 Drought","volume":"32","author":"Barriopedro","year":"2019","journal-title":"J. Clim."},{"key":"ref_44","unstructured":"WMO (2018). Statement on the State of the Global Climate in 2017, World Meteorological Organization. Available online: https:\/\/library.wmo.int\/index.php?lvl=notice_display&id=20220#.YBLgL-hKhjk."},{"key":"ref_45","unstructured":"Copernicus (2021, February 11). Climate in 2017\u2014European Wet and Dry Indicators. Available online: https:\/\/climate.copernicus.eu\/climate-2017-european-wet-and-dry-indicators."},{"key":"ref_46","unstructured":"WMO (2019). Statement on the State of the Global Climate in 2018, World Meteorological Organization. Available online: https:\/\/library.wmo.int\/index.php?lvl=notice_display&id=20799#.YBPg5-hKhjk."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1080\/16000870.2019.1704342","article-title":"Impact of strong and extreme El Ni\u00f1os on European hydroclimate","volume":"72","author":"King","year":"2020","journal-title":"Tellus A"},{"key":"ref_48","first-page":"181","article-title":"ENSO influence on Europe during the last centuries","volume":"28","author":"Xoplaki","year":"2007","journal-title":"Clim. Dyn."},{"key":"ref_49","unstructured":"Roesli, H.-P. (2021, February 12). A Westward Travelling ULL Induced the Rapid Reversal of a Pressure Gradient across the Alpine Range in Mid-March 2016. Available online: http:\/\/eumetsat.int\/upper-level-low-ull-over-northern-europe."},{"key":"ref_50","unstructured":"WMO (2011). Statement on the State of the Global Climate in 2010, World Meteorological Organization. Available online: https:\/\/library.wmo.int\/doc_num.php?explnum_id=7739."},{"key":"ref_51","unstructured":"WMO (2013). Statement on the State of the Global Climate in 2012, World Meteorological Organization. Available online: https:\/\/library.wmo.int\/index.php?lvl=notice_display&id=14750#.YBP0s-hKhjk."},{"key":"ref_52","unstructured":"WMO (2017). Statement on the State of the Global Climate in 2016, World Meteorological Organization. Available online: https:\/\/library.wmo.int\/index.php?lvl=notice_display&id=19835#.YBP9VOhKhjk."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"23939","DOI":"10.1029\/94JB02122","article-title":"Atmospheric pressure loading effects on Global Positioning System coordinate determinations","volume":"99","author":"Blewitt","year":"1994","journal-title":"J. Geophys. Res."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1007\/s00190-020-01466-5","article-title":"Robust estimation of spatially varying common-mode components in GPS time-series","volume":"95","author":"Kreemer","year":"2021","journal-title":"J. Geod."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"20190505","DOI":"10.1098\/rstb.2019.0505","article-title":"A Historical, geographical and ecological perspective on the 2018 summer drought","volume":"375","author":"Wouter","year":"2020","journal-title":"Phil. Trans. R. Soc. B"},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"124","DOI":"10.1175\/2010JCLI3590.1","article-title":"An Atmospheric Teleconnection Linking ENSO and Southwestrn European Precipitation","volume":"24","author":"Shaman","year":"2011","journal-title":"J. Clim."},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"1080","DOI":"10.1002\/2015JB012253","article-title":"Extracting the regional common-mode component O GPS station position time series from dense continuous network","volume":"121","author":"Tian","year":"2016","journal-title":"J. Geophys. Res. Solid Earth"},{"key":"ref_58","doi-asserted-by":"crossref","unstructured":"Pan, Y., Chen, R., Ding, H., Xu, X., Zheng, G., Shen, W., and Xiao, I. (2019). Common Mode Component and Its Potential Effect on GPS-Inferred Three-Dimensional Crustal Deformations in the Eastern Tibetan Plateau. Remote Sens., 11.","DOI":"10.3390\/rs11171975"},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"1621","DOI":"10.1029\/2001GL014248","article-title":"Euro Mediterranean rainfall and ENSO\u2014A seasonally varying relationship","volume":"29","author":"Mariotti","year":"2002","journal-title":"Geophys. Res. Lett."},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"1218","DOI":"10.1093\/gji\/ggx483","article-title":"Decadal variation in Earth\u2019s oblateness (J2) from satellite laser ranging data","volume":"212","author":"Cheng","year":"2018","journal-title":"Geophys. J. Int."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"e2020JB019421","DOI":"10.1029\/2020JB019421","article-title":"Variation of Earth\u2019s Oblateness J2 on Interannual-to-Decadal Timescales","volume":"125","author":"Chao","year":"2020","journal-title":"J. Geophys. Res. Solid Earth"}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/13\/8\/1554\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T05:49:00Z","timestamp":1760161740000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/13\/8\/1554"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,4,16]]},"references-count":61,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2021,4]]}},"alternative-id":["rs13081554"],"URL":"https:\/\/doi.org\/10.3390\/rs13081554","relation":{},"ISSN":["2072-4292"],"issn-type":[{"type":"electronic","value":"2072-4292"}],"subject":[],"published":{"date-parts":[[2021,4,16]]}}}