A Universal Multifractal Approach to Assessment of Spatiotemporal Extreme Precipitation over the Loess Plateau of China

Abstract

Abstract. Extreme precipitation (EP) is a major external agent driving various natural hazards in the Loess Plateau (LP), China. Yet, the characteristics of spatiotemporal EP responsible for such hazardous situations remain poorly understood. We integrate universal multifractals with a segmentation algorithm to characterize a physically meaningful threshold for EP (EPT). Using daily data from 1961 to 2015, we investigate the spatiotemporal variation of EP over the LP. Our results indicate that EPTs range from 17.3 to 50.3 mm/d while the mean annual EP increases from 35 to 138 mm from northwest to southeast LP. Further, EP frequency (EPF) has historically spatially varied from 54–116 days, with the highest EPF occurring in the mid-southern and southeastern LP where precipitation is much more abundant. However, EP intensities tend to be strongest in the central LP where precipitation also tends to be scare, and get progressively weaker as we move towards the margins (similarly with EP severity). An examination of atmosphere circulation patterns indicates that the central LP is the boundary where tropical cyclones reach furthest into inland China, resulting in the highest EP intensities and EP severities being in this area. Under the control of the East Asian monsoon, precipitation from June to September accounts for 72 % of the total amount, while 91 % of the total EP events are concentrated in June to August. Further, EP events occur, on average, 11 days earlier than the wettest part of the season. These phenomena are responsible for the most serious natural hazards in the LP, especially in the Central region. Spatiotemporally, 91.4 % of the LP has experienced a downward trend of precipitation, while 62.1 % of the area has experienced upward trends of the EP indices, indicating the potential risk of more serious hazardous situations.

Spatiotemporally varied extreme precipitation events simultaneously controlled by multiple circulation factors in China's Loess Plateau

“…In summer, the southeastern part is influenced by the South Asian Monsoon and East Asian Monsoon due to the Pacific high pressure, which brings abundant warm and humid water vapour from the sea (Wang et al ., 2019). Because of the high‐pressure system of the Tibet Plateau, the humidity gradually decreases from the southeast to the northwest (Figure 12b) (Zhang et al ., 2020). The western part is controlled by the westerly system, and the water vapour is mainly transported by the prevailing westerly wind in mid‐latitudes (Chen et al ., 2010).…”

“…For example, Zhang et al . (2020) examined the variation of EPE from 1961 to 2015 and concluded the EPE in the Loess Plateau intensified. Wang et al .…”

“…For example, Zhang et al . (2020) concluded the EPE intensified from 1961 to 2015 in the Loess Plateau, whereas Sun et al . (2016) explored SDII and CDD showed significant decreases and increases during 1960–2013, respectively.…”

“…The Loess Plateau in north China has an area of 620,000 km 2 (Zhang et al ., 2020). The region is mainly influenced by the continental monsoon climate, and heavy rainstorms account for 70% of the annual total precipitations concentrating from July to September (Li et al ., 2009; Wang et al ., 2020).…”

Contribution of climate change and urbanization to the variation of extreme precipitation in the urban agglomerations over the Loess Plateau

“…This seriously affects the economic development and ecological security of the LP. (Zhang et al, 2020;Zhao, Li, & Zhu, 2017). In the last 20 years, the LP has experienced rapid urbanization.…”