Temporal-spatial variability of modern climate in the Altai Mountains during 1970-2015

have been detailedly investigated [11–18]. The increasing trends were revealed in mean annual temperature (MAT) [17–18] and mean annual precipitation (MAP) [14, 16] in the Tianshan Mountains over the past decades. The Altai Mountains (Fig 1A), the second largest mountain system within ACAZ and located in the north of the Tianshan Mountains, stretch across Russia, Mongolia, China and Kazakhstan. They are of scientific concern in term of paleoclimatic studies for understanding the interaction between the westerlies and the Asian summer monsoon and for exploring the associations between climate modulation and cultural evolution along the ‘Eurasian Steppe Belt’ [19–25]. Compared with the detailed investigations about modern climate changes in the Tianshan Mountains, modern climate changes are poorly analyzed in the Altai Mountains. For example, Malygina et al. [26] detected the precipitation changes in the Russian Altai and in the Mongolian Altai in the interval spanning from 1959 to 2014 and estimated the possible driving factors. Zhang et al. [27] based on a converse moisture character during the Holocene interval and analyzed the different time-scale (i.e., season, year, multi-decades and centennial/ millennial scales) climatic changes in the Russian Altai and in the Chinese Altai. It is clear that modern climate trends were not systematically investigated in terms of different sub-regions and of different elevations in the Altai Mountains. Based on the selected meteorological data in the Altai Mountains, we detailedly investigated

the temporal-spatial changes of modern climate of the Altai Mountains during 1970–2015. This study is very important for assessing the influences of climate changes on its physical environments and ecosystem stabilities or securities and for improving the abilities for ecologi- cal management in the whole Altai Mountains. Regional setting Located in the transition zone between the Siberian taiga forests and the Central Asian deserts, the Altai Mountains stand out from its surrounding territories with their unique diversity of Fig 1. Geographic location of the Altai Mountains (a) and the related meteorological stations in the Altai Mountains (white area) (b). The Altai Mountains are divided into three sub-regions (1, 2 and 3) and the detailed information of meteorological stations is showed in Table 1. The image was downloaded from the Natural Earth website (http://www. naturalearthdata.com/ ). https://doi.org/10.1371/journal.pone.0230196.g001 PLOS ONE Modern climate characters in the Altai Mountains PLOS ONE | https://doi.org/10.1371/journal.pone.0230196 March 17, 2020 2 / 15 Funding: This research was financially supported by Strategic Priority Research Program of Chinese Academy of Sciences (No. XDA20020101), by China Postdoctoral Science Foundation (No. 2019M663864), and by the Western Young Scholar Program-B of Chinese Academy of Sciences (No. 2018-XBQNXZ-B-020). The primary analysis of Russian meteorological data was done with support of Russian Science Foundation (No. 17-77-10041). The funders had no role in study design, data collection and analysis, decision to

publish, or preparation of the manuscript. Competing interests: The authors declare no competing interests. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.