Moderate rain intensity increased and contributes significantly to total rain change in recent decades over the Qinghai-Tibet Plateau

Abstract

Study region: Qinghai-Tibet Plateau Study focus: We focused on characterization and contributions of classified rain to total rain change. For each decade between 1981 and 2020, rain events were categorized into four non-overlapping groups based on percentile thresholds: light rain (LRI; 99th percentile), with trends detected using robust non-parametric approach. Thereafter, we used relative weights and multiple regression models to assess the contribution of each categorized rain to the overall rainfall change. New hydrological insights for the region: Classified rain represented rain features better than mean wet rain intensity. Mean rain intensity fluctuated as classified rain, although > 50th percentiles (MRI, HRI, and VHRI) increased more. Weighted linear combination revealed that during 1981–1990, 1991–2000, 2001–2010, and 2011–2020, majority of explained variance in total rain intensities was attributed to MRI with 32%, 36%, 35%, 40% model R2, respectively. The MRI year-to-year variation was also consistent with total wet rain (r > 0.8), implying that MRI was the most significant predictor of total rain change (p < 0.05). Although the annual wet rain, MRI, HRI, and VHRI all had positive linkages with temperature, it is still important to investigate the variability of classified rain intensity and frequency in the context of other climatic factors. This research will aid the understanding of changes in classified rain events.

Keywords

• Rain frequency
• Rain intensity
• Multiple linear regression
• Relative weights
• Climate change
• Tibetan Plateau