Drought, a normal part of the climate system, poses a significant threat to society, the environment, and the global economy. Droughts have far-reaching impacts on agriculture, water resources, ecological systems, and human livelihoods. As water resources become increasingly vulnerable to competing demands due to climate change, population growth, and expanding economies, understanding the spatiotemporal patterns and characteristics of droughts is essential for effective water management and policy-making.
In a new study published in the Journal of Hydrometeorology, researchers from the Institute of Atmospheric Physics (IAP) at the Chinese Academy of Sciences and the University of California, San Diego, shed light on the distinct characteristics and evolution of droughts across China. By analyzing multiple drought indices, including the Standardized Precipitation Evapotranspiration Index (SPEI) and the Palmer Drought Severity Index (PDSI), the study identified two dominant types of droughts in China, each with its own unique spatial and temporal characteristics.
1. Northern China (NC) Droughts
NC droughts are predominantly precipitation-driven and primarily occur during the summer months (June to September). These droughts are characterized by the absence or inadequacy of rainfall, resulting in shortfalls in water availability for agriculture and ecosystems.
2. Southern China (SC) Droughts
In contrast, SC droughts are primarily temperature-driven and occur during the winter and spring seasons (November to April). SC droughts are often characterized by warm and dry conditions, with elevated temperatures increasing the rate of evapotranspiration and further exacerbating water deficiencies.
The study revealed that NC and SC droughts exhibit different evolution patterns. NC droughts typically develop rapidly, reaching their peak intensity in a matter of weeks or months. They are primarily modulated by the variation of summer monsoon precipitation, influenced by factors such as the El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD).
On the other hand, SC droughts tend to evolve more slowly and can persist for extended periods, lasting several months or even years. Their development is driven by large-scale atmospheric circulation patterns, including the East Asian winter monsoon and the modulation of the mid-high latitude westerly jet stream.
The findings of this study contribute to a deeper understanding of drought characteristics in China and highlight the importance of considering both precipitation and temperature when analyzing droughts. This knowledge is crucial for improving drought monitoring and prediction systems, as well as developing targeted drought risk mitigation strategies. By characterizing the different types of droughts and their respective evolution patterns, policymakers and water managers can enhance water resources management and reduce the societal and economic impacts of droughts in China.
