The response of extreme rainstorm to global climate pattern changes in the loess plateau

The response of extreme rainstorm to global climate pattern changes in the loess plateau

Shaobo Long^1,3、Jianen Gao^1,2,3*、Huijuan Li⁵、Zhe Gao⁴、minmin Qiang^1,3、Sixuan Liu^1,3

1. Institute of Soil and Water Conservation, Northwest Agriculture and Forestry University, 712100, Yangling, Shaanxi, China.
2. Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, 712100, Yangling, Shaanxi, China.
3. Research Center on Soil and Water Conservation, Ministry of Water Resources, 712100, Yangling, Shannxi, China.
4. College of Water Resources and Architectural Engineering, Northwest Agriculture and Forestry University, 712100, Yangling, Shaanxi, China.
5. Institute of Geographic Sciences and Natural Research, CAS, 100101, Beijing, China.

Abstract: The loess plateau is the region with the most serious soil and water problems in the world, the soil erosion mainly occurs in the season of rainfall, especially the extreme rainstorm has great influence on soil erosion. In recent years, under the background of global climate change, extreme rainstorm occurs frequently in the loess plateau, causes a series of soil damage, was difficult to predict. Therefore, it is a great significance to study the rule of extreme rainstorm for the soil erosion in the loess plateau. Based on the daily rainfall data of 56 meteorological stations and global sea surface temperatures (SST) data in the last 60 years, the effects of El Niño on extreme rainstorm were studied by using empirical orthogonal function (EOF), wavelet transform, and other statistical methods. The results show:

• (1) The extreme rainstorm has obvious spatial distribution characteristics, which decreases gradually from the south to the north of the loess plateau; Temporal variation of extreme rainstorm has obvious decadal oscillation, showing a decreasing trend from 1982 to 2012 and an increasing trend after 2012.
• (2) There was a significant positive correlation between the time coefficient of EOF1 for SST and the extreme rainstorm (P < 0.05). Wavelet analysis shows that Both extreme rainstorm and SST anomaly have a 30-year cycle, with the time change becoming more dramatic after 2012.
• (3) El Niño has obvious influence on the extreme rainstorm in the loess plateau region. Extreme rainstorm can be predicted about 1 year in advance by the change of SST anomaly. This is of great significance to the study of extreme rainfall erosion in the loess plateau.

Keywords: The loess plateau; Extreme rainstorm; El Niño

Funding:

1. The National key Research and Development Program of China (No.2017YFC0504703).
2. National Natural Science Foundation of China (No. 41877078, 41371276).
3. Knowledge Innovation Program of the Chinese Academy of Sciences (No.A315021615).