Abstract:

The Qinghai-Tibet Plateau (QTP) is known as the “Water Tower of Asia” and is also the origin of major rivers in China. Study on changes in precipitation properties is crucial to assessment of climate change impact on water resources, agriculture and husbandry, ecosystems, and disasters such as drought, flash floods, and landslides. However, due to the complex of topography, and lack of spatial coverage of long-term in-situ observations, our understanding on changes in precipitation amount, frequency and related extremes is limited. In recent years, various precipitation analysis or derived datasets have been developed, but we do not have much knowledge on if these multi-source datasets are representative in reflecting actual climate change and consistent with in-situ observations in the QTP. The consistencies and differences in changes of the rainy season precipitation amount, frequency and extreme precipitation (R95ptot and R95pday) are comprehensively analyzed between the in-situ rain gauge observations and five analytical precipitation datasets (APHRO、CN05.1、CMFD、TRMM and GPCP) in this paper. In addition, changes of precipitation prosperities in three different climatic regions of QTP are assessed. It concludes that: (1) CN05.1 and CMFD datasets are generally consistent with the in-situ observations in terms of the trend of the regional average precipitation, the spatial distribution of precipitation, R95ptot and the trends, but have discrepancies in changes of precipitation days and extreme precipitation days. APHRO dataset underestimates increasing trends in precipitation total and frequency and gives opposite trends for extreme precipitation and frequency as compared to the in-situ observations on average. GPCP and TRMM datasets are too short for climate change study, overestimates change in number of rain days and exhibit opposite trend in total precipitation, but they are acceptable for trend estimates for extreme precipitation amount and frequency. (2) Based on the in-situ precipitation observations and with consideration of consistency of other analytical datasets, rainy season precipitation total and extreme amount, and number of extreme precipitation days over QTP show overall increasing trends from 1961 to 2019. However, uncertainty still exists in the understanding of precipitation frequency due to the large discrepancy between the in-situ observations and other analytical datasets. Regionally, the arid zone and the semi-arid zone seem to have experienced increasing trends in rainy season precipitation amount and frequency, and in extreme precipitation and frequency. For the semi-humid zone, a slight increase trend is detected in number of extreme precipitation days, and significant increase trends are found in precipitation total and extreme precipitation amount except for slight decrease trends in some of its eastern and central parts. In addition, regional averaged number of precipitation days has reduced mainly due to significant decrease in its eastern and southern parts.

Key words: The Qinghai-Tibet Plateau (QTP), Multi-source datasets, In-situ observations, Precipitation properties, Extreme precipitation, Trend, Climatic zones