The severity of drought and precipitation prediction in the eastern fringe of the Tibetan Plateau

Abstract

The trend, severity, and duration of drought in the eastern fringe of the Tibetan Plateau (EFTP) have been investigated using the Mann-Kendall (M-K) trend test, standardized precipitation index (SPI), and generalized extreme value (GEV), using data obtained from 438 rainfall stations and reanalysis datasets for the period 1961-2014. A recent drought trend is evident from a decrease in rainfall, with this mainly occurring on the eastern slope of the TP (< 3000-m elevation); this is attributed to downward air flows over the eastern slope of the Tibetan Plateau (TP) induced by TP heating. Recent droughts have also been more severe, with these again mostly occurring on the eastern slopes. The duration of drought illustrates that extreme droughts are becoming more frequent. The study also predicted summer precipitation, due to its crucial role in drought research in the EFTP. Results show that the preceding May-June-July (MJJ) averaged column-integrated meridional water vapor transport (MWVT) from the South China Sea (SCS), Philippine Sea, and tropical western Pacific is a vital predictor of summer precipitation in the EFTP. A partial least squares (PLS) regression prediction model is therefore constructed, using the leading PLS components of preceding MJJ-averaged columnintegrated MWVT. Compared to the observed summer rainfall, the PLS prediction model performs an excellent reconstructed skill with a correlation of 0.81 and exhibits a promising forecast skill with a correlation of 0.67 (2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014). Results suggest that southerly moisture transport in early summer would help prevent summer drought in the EFTP.

Responses of soil moisture to regional climate change over the Three Rivers Source Region on the Tibetan Plateau

“…Studies have suggested that partial correlation can be used to study the correlation between two meteorological factors (Meng et al ., ; Zhao et al ., ; Bai et al ., ). The spatial distribution of the partial correlation coefficient between trended precipitation and GLDAS‐NOAH025 soil moisture with correlation statistical significance at or above the 95% level are shown in Figure .…”

Investigating Predictability of the TRHR Seasonal Precipitation at Long Lead Times Using a Generalized Regression Model with Regularization

“…Consequently, the TRHR plays a critical role in providing invaluable ecological goods and serviced as well as other resources like energy and food. While great efforts have been devoted to studying teleconnections between the broader TP precipitation and large-scale climates (Benn and Owen, 1998;Shaman and Tziperman, 2005;Feng and Zhou, 2012;Dong et al, 2020), the quantitative studies focusing solely on the TRHR are rather limited and only looks at short lead times (Zhang et al, 2019;Zhao et al, 2019). In this study, we extend the forecast lead time up to 24 months and the performance are compared against some widely-used regression methods including OLS multi-linear regression, the EOF regression, and the CCA regression.…”

Climate modulation of summer rainstorm activity in eastern China based on the Tibetan Plateau spring heating

“…On average, urban temperatures in this region are 1-3°C higher than in surrounding rural environments (Voogt and Oke 2003), while summer air temperature over the TP is generally 4-6°C warmer than at an equivalent altitude in the free atmosphere. Zhao et al (2019a) emphasized that the eastern TP is a mainly heating source; it has important effect on the summer precipitation for the eastern slope of TP.…”