Spatiotemporal Covariability of Extreme Precipitation and Integrated Vapour Transport Over the Tibetan Plateau During 1979–2015

ABSTRACT Extreme precipitation and atmospheric moisture transport are closely linked components of the Tibetan Plateau (TP) hydroclimate, but statistical covariability should be distinguished from causal control. We analyse extreme‐precipitation and integrated vapour transport (IVT) indices over 1979–2015 using APHRODITE precipitation and ERA5 reanalysis. The precipitation and moisture‐transport products used in the original workflow were evaluated against independent station and radiosonde observations: APHRODITE showed the best overall performance among the evaluated precipitation products, while ERA5‐derived IVT agreed substantially better with radiosonde observations than NCEP–NCAR. Regional‐mean R95p, R10mm and Rx1day increased by 7.02 mm decade −1 , 0.40 days decade −1 and 0.77 mm decade −1 , respectively. IVT90p increased by 1.34 kg m −1 s −1 decade −1 ( Z = 1.79), but the regional‐mean trend did not reach the two‐sided 0.05 significance level; R150IVT and IVTmax likewise showed non‐significant increases of 0.65 days decade −1 and 1.61 kg m −1 s −1 decade −1 . The leading EOF explains 66.0%, 52.6% and 26.3% of the variance in R95p, R10mm and Rx1day, respectively, compared with 23.6% for IVT90p and 21.9% for R150IVT. These results quantify historical spatial and temporal covariability over 1979–2015 without implying hydrological risk, statistical non‐stationarity, or deterministic climate control.