Understanding the spatiotemporal dynamics of vegetation drought and its time-lag link with teleconnection factors on the Loess Plateau

Abstract

Study region: Loess Plateau (LP), China Study focus: This study investigated the spatiotemporal dynamics of vegetation drought on the LP using an improved temperature vegetation drought index (ITVDI) and explored its time-lag link with teleconnection factors. New hydrological insights for the region: Findings indicated that: (1) ITVDI is an effective tool for vegetation drought monitoring; (2) the vegetation droughts were primarily characterized by mild to moderate intensity, with spring manifesting the most expansive drought-stressed areas (about 61.89% of pixels); (3) approximately 71.69% of the region exhibited an increasing trend in vegetation drought, particularly in the Ordos Plateau and typical agricultural zones; (4) long-term dependence in vegetation drought patterns was observed in 70.65% of the region, characterized by forest-covered areas becoming wetter, crop-covered areas getting drier, and grass-covered areas shifting from dryness to wetness; (5) the lag time between ITVDI and Southern Oscillation Index (SOI) was generally less than four months (approximately 71.01% of pixels), while ITVDI lagged behind Pacific Decadal Oscillation (PDO) mostly between 6 and 8 months (around 75.77% of pixels); (6) extremum correlation coefficients effectively determined the lag time for vegetation drought behind large-scale circulation factors, considering both monotonic and non-monotonic relationships. These insights contribute to drought monitoring, risk assessment, and early warning system, thereby providing valuable support for drought mitigation and management strategies in the LP and similar regions worldwide.

Keywords

• Temperature vegetation drought index
• Pre-whitening Mann-Kendall method
• Mutual information
• ENSO
• PDO