ORIGINAL PAPER Spatiotemporal variations of the twentieth century Tibetan Plateau precipitation based on the monthly 2.5° reconstructed data Samuel S. P. Shen 1,2 & Gregori Clarke 3 & Bo-Wen Shen 1 & Tandong Yao 4 Received: 23 February 2017 /Accepted: 15 December 2017 # Springer-Verlag GmbH Austria, part of Springer Nature 2017 Abstract This paper studies the spatiotemporal variations of precipitation over the Tibetan Plateau (TP) region with latitude and longitude ranges of (25° N, 45° N) and (65° E, 105° E) of the twentieth century from January 1901–December 2000. A long-term (January 1901–December 2009) TP monthly precipitation dataset with 2.5° latitude-longitude resolution is generated in this paper using spectral optimal gridding (SOG) method. The method uses the Global Precipitation Climatology Center (GPCC) ground station data to anchor the basis of empirical orthogonal functions (EOFs) computed from the Global Precipitation Climatology Project (GPCP) data. Our gridding takes teleconnection into account and uses data from stations both within and outside of the TP region. While the annual total precipitation increased at an approximate rate of 2.6 mm per decade in the period of 1971–2000 exists, no significant increase of TP precipitation from 1901 to 2000 was found. Our rate is less than those of previous publications based only on the TP stations because our data consider the entire TP region, including desert and high-altitude areas. An analysis of extremes and spatiotemporal patterns of our data shows that our reconstructed data can properly quantify the reported disasters of flooding and droughts in India, Bangladesh, and China for the following events: flooding in 1988 and 1998 and drought in 1972. Our time-frequency analysis using the empirical mode decomposition method shows that our nonlinear trend agrees well with the linear trend in the period from 1971 to 2000. The spatiotemporal variation characteristics documented in this paper can help understand atmospheric circulations on TP precipitation and validate the TP precipitation in climate models. 1 Introduction This paper studies the spatiotemporal variations of precip- itation over the Tibetan Plateau (TP) region with latitude and longitude ranges of (25° N, 45° N) and (65° E, 105° E) and a total area of 2.6 million km 2 (Fig. 1). The TP’ s high altitude, long-time snow cover in a year over the high- altitude area, and large-sized glacier make the TP a Bwater tower^ for hundreds of million people in the surrounding countries (Xu et al. 2008). The Bwater tower^ provides its supply via various rivers originating from TP, such as the Yangtze and Yellow Rivers of China. Accurate documenta- tion of the spatiotemporal distribution of TP precipitation is an important water resource database for the TP and its surrounding regions (Gao et al. 2015; Liu and Yin 2001; Yao et al. 2004). The documentation can contribute not only to the progress of climate science but also benefit businesses, the general public, and governments by en- abling optimal policymaking and risk management deci- sions (Shen et al. 2015; Zhang et al. 2015). Quantification of the TP precipitation’ s spatiotemporal variation in a long- time history motivated many researches within recent years (Yao et al. 2012, 2013, and references therein). However, most published studies have been limited by the short his- tory of observation stations, which often have low eleva- tions. The systematic station observations have been made only since 1961, and elevations of the observation locations are all below 5000 m (Xu et al. 2008). The historical records of satellite observations are even shorter, e.g., the Global Precipitation Climatology Project (GPCP) only began in 1979 (Adler et al. 2003; Huffman et al. 2009). * Samuel S. P. Shen sam.shen@sdsu.edu 1 Department of Mathematics and Statistics, San Diego State University, San Diego, CA, USA 2 Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA 3 Computational Science Research Center, San Diego State University, San Diego, CA, USA 4 Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China Theoretical and Applied Climatology https://doi.org/10.1007/s00704-017-2357-5