Drought Events over the Amazon River Basin (1993–2019) as Detected by the Climate-Driven Total Water Storage Change

Kunjun Tian,Cong Liu,Fupeng Li,Zhengtao Wang,Yang Xiao,Yu Gao

doi:10.3390/rs13061124

Abstract

The Gravity Recovery and Climate Experiment (GRACE) mission has measured total water storage change (TWSC) and interpreted drought patterns in an unparalleled way since 2002. Nevertheless, there are few sources that can be used to understand drought patterns prior to the GRACE era. In this study, we extended the gridded GRACE TWSC to 1993 by combining principal component analysis (PCA), least square (LS) fitting, and multiple linear regression (MLR) methods using climate variables as input drivers. We used the extended (climate-driven) TWSC to interpret drought patterns (1993–2019) over the Amazon basin. Results showed that, in the Amazon area with the resolution of 0.5°, GRACE, GRACE follow on, and Swarm had correlation coefficients of 0.95, 0.92, and 0.77 compared with climate-driven TWSCS, respectively. The drought patterns assessed by the climate-driven TWSC were consistent with those interpreted by the Palmer Drought Severity Index and GRACE TWSC. We also found that the 1998 and 2016 drought events in the Amazon, both induced by strong El Niño events, showed similar drought patterns. This study provides a new perspective for interpreting long-term drought patterns prior to the GRACE period.

Highlights

We found that the climate-driven total water storage change (TWSC) fit well with the Gravity Recovery and Climate Experiment (GRACE) data in both training and testing periods, indicating that our combined method performed well in deriving the climate-driven TWSC for the Amazon basin
We detected the drought events that were occurred in the Amazon basin using the climate driven TWSC (1993–2019) as derived by combining principal component analysis (PCA), least square (LS), and Firstly, we used the GRACE TWSC and the climate drivers from April 2002 to March
The GRACE TWSC was used to test the uncertainties of the climatedriven TWSC in both training and testing periods

Summary

Introduction

This study provides a new perspective for interpreting long-term drought patterns prior to the GRACE period. As a result of global changes, hydrological extremes such as drought events are increasing. The time-variable gravity field model, observed by the GRACE mission, collects detailed changes in the Earth’s gravity field and infers the total water storage change (TWSC) over large continental regions with unprecedented precision [8]. The GRACE-derived TWSC interprets all information contained in vertical water contents, such as surface water, soil moisture, and ground water, which are clearly of more value to estimate the total water storage during the drought period [9,10]. The GRACE TWSC holds unique potential to study hydrological drought events over large-scale river basins. It is documented that the GRACE TWSC has made a great contribution to the detection of hydrological droughts [11,12]

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