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You searched for id:"oai:lup.lub.lu.se:1dec9d4e-e626-42f5-8c8a-ea6651fc54b4". One record found.

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University of Lund

1. Du, Yiheng. Present and future precipitation variations in the source region of the Yangtze River, China.

Degree: 2021, University of Lund

The source region of the Yangtze River (SRYR), the origin of the longest river in China, is an area with high-mountains and river ecotones that face considerable challenges under climate change. Precipitation is fundamental for sustainable ecosystems in this area and for the downstream water supplies. Thus, this study investigated the present and future patterns of precipitation variation in the SRYR. To investigate historical climate characteristics of the SRYR, analysis of hydro-climatic components during 1957-2013 was performed. Temperature in the SRYR increased at a rate of 0.34°C/decade, precipitation and evaporation increased by 11.4 and 7.6 mm/decade, respectively. Runoff depth increased by 3.3 mm/decade. Considering the water balance, annual water storage was constant despite a continuous small negative trend. Increase in precipitation is mainly caused by increasing evapotranspiration, leading to the relatively stable water storage during the study period, which also suggests an accelerating water cycle in the SRYR. This knowledge is essential for the understanding of water resources conditions in the area. Rainy season precipitation (June-August) in the SRYR accounts for approximately 70% of the annual total, and its anomalies are essential for ecosystem resilience. Hence, analysis of rainy season precipitation variability in relation to sea surface temperature (SST) anomalies as well as large-scale circulations including El Niño Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) was conducted. Results indicate that the leading modes of rainy season precipitation variability can be explained by the variability of SST together with an integrated effect of ENSO and PDO. The influence of ENSO and PDO will enhance/decrease when they are in-/out-of-phase, respectively. Negative PDO induces more precipitation in La Niña years than in El Niño years for the SRYR, especially over central and eastern parts of the basin. Positive PDO induces precipitation decrease, and El Niño enhances the decrease. The mechanism behind this pattern is atmospheric circulation affecting the strength of westerlies that transport moisture to the inland areas and as well local convergence conditions. Results have implications for predicting the rainy season precipitation for coming decades over the study area. If the current negative PDO phase continues together with more frequent extreme La Niña events, as suggested in other research, more precipitation during rainy season is expected over the SRYR. To further quantify precipitation variability, a multi-space model for seasonal precipitation prediction was developed using principal component analysis (PCA) and artificial neural network (ANN). Correlation analysis shows that the most important climate indices for precipitation in the SRYR vary depending on the season and spatial location. The North Atlantic Oscillation (NAO), Polar/Eurasia Pattern (POL), Southern Oscillation Index (SOI), and Scandinavia Pattern (SCA) events have influence on precipitation in the SRYR during…

Subjects/Keywords: Oceanography, Hydrology, Water Resources; Meteorology and Atmospheric Sciences; Precipitation; water balance; ENSO; PDO; Yangtze River; Tibet Plateau; future projections

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APA (6th Edition):

Du, Y. (2021). Present and future precipitation variations in the source region of the Yangtze River, China. (Doctoral Dissertation). University of Lund. Retrieved from https://lup.lub.lu.se/record/1dec9d4e-e626-42f5-8c8a-ea6651fc54b4 ; https://portal.research.lu.se/ws/files/90496380/Yiheng_Du_web.pdf

Chicago Manual of Style (16th Edition):

Du, Yiheng. “Present and future precipitation variations in the source region of the Yangtze River, China.” 2021. Doctoral Dissertation, University of Lund. Accessed February 26, 2021. https://lup.lub.lu.se/record/1dec9d4e-e626-42f5-8c8a-ea6651fc54b4 ; https://portal.research.lu.se/ws/files/90496380/Yiheng_Du_web.pdf.

MLA Handbook (7th Edition):

Du, Yiheng. “Present and future precipitation variations in the source region of the Yangtze River, China.” 2021. Web. 26 Feb 2021.

Vancouver:

Du Y. Present and future precipitation variations in the source region of the Yangtze River, China. [Internet] [Doctoral dissertation]. University of Lund; 2021. [cited 2021 Feb 26]. Available from: https://lup.lub.lu.se/record/1dec9d4e-e626-42f5-8c8a-ea6651fc54b4 ; https://portal.research.lu.se/ws/files/90496380/Yiheng_Du_web.pdf.

Council of Science Editors:

Du Y. Present and future precipitation variations in the source region of the Yangtze River, China. [Doctoral Dissertation]. University of Lund; 2021. Available from: https://lup.lub.lu.se/record/1dec9d4e-e626-42f5-8c8a-ea6651fc54b4 ; https://portal.research.lu.se/ws/files/90496380/Yiheng_Du_web.pdf

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