Because of the influence of different weather systems and topography, much of northwest China is arid compared to the southeast coast of China. Although extreme precipitation events (EPE) are rare in this region, short duration, high intensity, and localized heavy rainfall can cause natural disasters. Mountain torrents, or a combination of large-scale sliding floodwater and mud, as well as landslides have resulted from EPE events. In recent years, EPE occurrences in Northwest China have increased, causing more serious disasters and disrupting the fragile ecosystem of the arid biome. To understand what is driving more frequent extreme precipitation in Northwest China, scientists broke down several key atmospheric components, hoping to find the source of change.
Dr. Shan Lu from the Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions, Northwest Institute of Eco-Environment and Resources, along with her colleagues, have published their new findings about EPE frequency changes across Northwest China in Advances in Atmospheric Sciences. Results show that EPE have been the most significant contributor to the total precipitation in Northwest China. Within the arid region, the westerly and plateau zones have seen the most impactful EPE increase. Regarding seasonal effects, EPE have started earlier, and the last annual event is trending later. At the same time, researchers observed the opposite phenomenon in the monsoon regions of Southeast China.
“The possible mechanisms were investigated based on the interdecadal shift in EPE, said Dr. Lu. “The mechanisms behind EPE are very complex.”
Summer atmospheric circulation, water vapor transport, and atmospheric instability over Northwest China varied greatly throughout the decades analyzed in the study. However, an abrupt increase in EPE is apparent just before and consistently after 1986. Conversely, the conditions in the monsoon zone suppressed summer EPE development and occurrence after 1986.
Future studies may need to focus on the influence of topography on EPE. Additionally, strengthening ecological protection and enhancing disaster prevention and awareness are the best measures to effectively deal with the adverse effects of environmental change.