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Minimizing the effects of filtering on catchment scale GRACE solutions
Author(s) -
Dutt Vishwakarma Bramha,
Devaraju Balaji,
Sneeuw Nico
Publication year - 2016
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1002/2016wr018960
Subject(s) - amplitude , environmental science , drainage basin , attenuation , signal (programming language) , water storage , hydrology (agriculture) , structural basin , scaling , climate change , series (stratigraphy) , usable , scale (ratio) , computer science , remote sensing , geology , mathematics , physics , geography , geomorphology , paleontology , oceanography , geometry , cartography , geotechnical engineering , quantum mechanics , optics , inlet , programming language , world wide web
The Gravity Recovery and Climate Experiment ( grace ) satellite mission has provided time variable gravity information since its launch in 2002. Due to short‐wavelength noise, the total water storage variations over a catchment observed from grace are usable only after filtering. Filtering smooths both the signal and the noise, inevitably changing the nature of the estimated total water storage change. The filtered estimates suffer from attenuation and leakage, which changes the signal characteristics. Several studies have mainly focused on correcting the changed amplitude with the aid of hydrological models. In this study, it is demonstrated that in addition to the amplitude loss, also significant phase change in the time series of total water storage over a region can occur. The phase change due to leakage from nearby catchments can be around20 °to30 °for catchments with moderate size, which makes it difficult to retrieve signal by only scaling. We propose a strategy to approach the true time series with improved phase and amplitude. The strategy is independent of any hydrological model. It is first demonstrated in a closed‐loop environment over 32 catchments, where we show that the performance of our method is consistent and better than other model‐dependent approaches. Then we also discuss the limitations of our approach. Finally we apply our method to the grace level 2 products for 32 catchments.