Water is arguably our most precious resource, which is related to the hydrological cycle, climate change, regional drought events, and water resource management. In Turkey, besides traditional ...hydrological studies, Terrestrial Water Storage (TWS) is poorly investigated at a continental scale, with limited and sparse observations. Moreover, TWS is a key parameter for studying drought events through the analysis of its variation. In this paper, TWS variation, and thus drought analysis, spatial mass distribution, long-term mass change, and impact on TWS variation from the parameter scale (e.g., precipitation, rainfall rate, evapotranspiration, soil moisture) to the climatic change perspective are investigated. GRACE (Gravity Recovery and Climate Experiment) Level 3 (Release05-RL05) monthly land mass data of the Centre for Space Research (CSR) processing center covering the period from April 2002 to January 2016, Global Land Data Assimilation System (GLDAS: Mosaic (MOS), NOAH, Variable Infiltration Capacity (VIC)), and Tropical Rainfall Measuring Mission (TRMM-3B43) models and drought indices such as self-calibrating Palmer Drought Severity (SCPDSI), El Niño–Southern Oscillation (ENSO), and North Atlantic Oscillation (NAO) are used for this purpose. Turkey experienced serious drought events interpreted with a significant decrease in the TWS signal during the studied time period. GRACE can help to better predict the possible drought nine months before in terms of a decreasing trend compared to previous studies, which do not take satellite gravity data into account. Moreover, the GRACE signal is more sensitive to agricultural and hydrological drought compared to meteorological drought. Precipitation is an important parameter affecting the spatial pattern of the mass distribution and also the spatial change by inducing an acceleration signal from the eastern side to the western side. In Turkey, the La Nina effect probably has an important role in the meteorological drought turning into agricultural and hydrological drought.
The present study aimed to understand the effect of filtering on global and regional terrestrial water storage (TWS) signal derived from Gravity Recovery and Climate Experiment (GRACE) satellite data ...obtained from Centre for Space Research (CSR), Jet Propulsion Laboratory (JPL) and GeoForschungsZentrum (GFZ). Our results show that the CSR and GFZ solutions were compatible after processing, while for JPL solutions were more challenging to eliminate data noises using filtering techniques. Concerning the effect of changing the Gauss filtering radius on TWS, differences were found to be at a maximum ±5 cm in annual amplitude and ±1 cm/yr in trend sections; mostly apparent in regions where the signal was anomalous. Various destriping methods may led to data misinterpretation, loss of available TWS signal or confusion. Finally, new releases of CSR (RL06) showed an improvement compared to former versions particularly for solutions for the specific time of year chosen in this study.
Gravity Recovery and Climate Experiment (GRACE) and the GRACE-Follow-On (GRACE-FO) gravimetric missions provide essential data for remotely measure large-scale Terrestrial Water Storage (TWS) changes ...on a regional and global scale. However, during the operating time of the gravimetric missions, monthly or almost yearly data gaps may induce and fail to provide continuous information. Quantifying and predicting the TWS variations is very important for uninterrupted environmental monitoring, to be prepared for the consequences of the climatic change and water resources studies. This paper proposes to predict the TWS variability of 19 global basins from 2019 to 2022 using the traditional Seasonal Autoregressive Integrated Moving Average, Error Trend Seasonal, and Singular Spectrum Analysis as newer time series analysis modeling and prediction approach. For this purpose, the integrated GRACE/GRACE-FO Level-3 Release 06 data from the German Research Centre (GFZ) have been privileged. The accuracy of the resulted TWS predictions has been evaluated based on the use of the mentioned approaches, the cross-validation method, and the root-mean-square-error. Using integrated GRACE/GRACE-FO data, the research strategy in this paper is to become a reference to study the TWS prediction of the new GRACE-FO mission and to bridge the gap between GRACE/GRACE-FO missions. For some global basins, the obtained TWS prediction results reveal a continuous negative or positive TWS during the study period 2019–2022. In conclusion, September 2020 and 2021 are expected to be important dates in terms of TWS decrease affecting all basins in different order of magnitude.
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