Evidence of daily hydrological loading in GPS time series over Europe
Loading deformations from atmospheric, oceanic, and hydrological mass changes mask geophysical processes such as land subsidence and tectonic or volcanic deformation. While it is known that hydrological loading plays a role at seasonal time scales, here we demonstrate evidence that also fast water storage changes contribute to daily Global Positioning System (GPS) height time series. So far, no clear strategy, i.e., no single conventional hydrological model, has been proposed for removing hydrological deformation from daily GPS height time series. Hydrological model predictions of total water storage anomalies tend to diverge and (substantially) deviate from Gravity Recovery and Climate Experiment (GRACE) observations, which however have a limited spatial and temporal resolution. Here, we suggest to overcome these limitations by assimilating GRACE data into a high-resolution (12.5 km) hydrological model. We tested this approach over Europe, and we found that accounting for daily hydrological mass changes reduces the root mean square scatter of GPS height time series almost by a factor of two when compared to monthly hydrological mass changes. We suggest that a GRACE-assimilating hydrological model would provide a promising option for removing hydrology-induced vertical deformation from GPS time series also at the global scale.
KeywordsGPS Vertical deformation Hydrogeodesy GRACE Assimilation
We thank Matt King and three anonymous reviewers, whose thoughtful comments improved the manuscript. GRACE solutions were obtained from the ITSG (https://www.tugraz.at/institutes/ifg/downloads/gravity-field-models/itsg-grace2016/). The GPS time series are available in SINEX format through the EPN website (ftp://igs.bkg.bund.de/EPNrepro2/products/).
Anne Springer performed the assimilation of GRACE data into CLM3.5 to produce the high-resolution total water storage reanalysis over Europe and wrote the manuscript. Makan Karegar analyzed the GPS time series, modeled the deformation and helped write the manuscript. Jürgen Kusche contributed to the interpretation of the results and helped improve the manuscript. Jessica Keune and Stefan Kollet performed the initial setup of the CLM3.5 model over Europe. Wolfgang Kurtz set up the interface between CLM3.5 and the parallel data assimilation framework (PDAF).
- Argus DF, Landerer FW, Wiese DN, Martens HR, Fu Y, Famiglietti JS, Thomas BF, Farr TG, Moore AW, Watkins MM (2017) Sustained water loss in California’s mountain ranges during severe drought from 2012 to 2015 inferred from GPS. J Geophys Res: Solid Earth 122(12):10559–10585. https://doi.org/10.1002/2017JB014424 CrossRefGoogle Scholar
- Flechtner F, Dobslaw H, Fagiolini E (2015) AOD1B Product Description Document for Product Release 05. Technical Report GRACE 327 - 750 (GR-GFZ-AOD-0001)Google Scholar
- Fu Y, Argus DF, Freymueller JT, Heflin MB (2013) Horizontal motion in elastic response to seasonal loading of rain water in the Amazon Basin and monsoon water in Southeast Asia observed by GPS and inferred from GRACE. Geophys Res Lett 40(23):6048–6053. https://doi.org/10.1002/2013GL058093 CrossRefGoogle Scholar
- Giorgi F, Jones C, Asrar GR (2009) Addressing climate information needs at the regional level: the CORDEX framework. WMO Bull 58:175–183Google Scholar
- Herring TA, Melbourne TI, Murray MH, Floyd MA, Szeliga WM, King RW, Phillips DA, Puskas CM, Santillan M, Wang L (2016) Plate boundary observatory and related networks: GPS data analysis methods and geodetic products. Rev Geophys 54(4):759–808. https://doi.org/10.1002/2016RG000529 CrossRefGoogle Scholar
- Ihde J, Habrich H, Sacher M, Söhne W, Altamimi Z, Brockmann E, Bruyninx C, Caporali A, Dousa J, Fernandes R, Hornik H, Kenyeres A, Lidberg M, Mäkinen J, Poutanen M, Stangl G, Torres JA, Völksen C (2014) EUREF’s contribution to national, European and global geodetic infrastructures. In: Rizos C, Willis P (eds) Earth on the edge: science for a sustainable planet. International association of geodesy symposia. Springer, Berlin, pp 189–196CrossRefGoogle Scholar
- Karegar MA, Dixon TH, Kusche J, Chambers DP (2018) A new hybrid method for estimating hydrologically induced vertical deformation from GRACE and a hydrological model: an example from central North America. J Adv Model Earth Syst 10(5):1196–1217. https://doi.org/10.1029/2017MS001181 CrossRefGoogle Scholar
- Khaki M, Hoteit I, Kuhn M, Awange J, Forootan E, van Dijk AIJM, Schumacher M, Pattiaratchi C (2017) Assessing sequential data assimilation techniques for integrating GRACE data into a hydrological model. Adv Water Resour 107:301–316. https://doi.org/10.1016/j.advwatres.2017.07.001 CrossRefGoogle Scholar
- Nahmani S, Bock O, Bouin MN, Santamaría-Gómez A, Boy JP, Collilieux X, Métivier L, Panet I, Genthon P, de Linage C, Wöppelmann G (2012) Hydrological deformation induced by the West African Monsoon: comparison of GPS, GRACE and loading models. Solid Earth, J Geophys Res. https://doi.org/10.1029/2011JB009102 CrossRefGoogle Scholar
- Scanlon BR, Zhang Z, Save H, Sun AY, Schmied HM, van Beek LPH, Wiese DN, Wada Y, Long D, Reedy RC, Longuevergne L, Döll P, Bierkens MFP (2018) Global models underestimate large decadal declining and rising water storage trends relative to GRACE satellite data. PNAS 115(6):E1080–E1089. https://doi.org/10.1073/pnas.1704665115 CrossRefGoogle Scholar
- Springer A (2019) A water storage reanalysis over the European continent: assimilation of GRACE data into a high-resolution hydrological model and validation. PhD thesis, Bonn University, BonnGoogle Scholar