Rising flood risks in semiarid South Asia driven by changing intraseasonal oscillations under global warming.
Jinhui Xie1, Pang-Chi Hsu1, June-Yi Lee2,3
1State Key Laboratory of Climate System Prediction and Risk Management/Key Laboratory of Meteorological Disaster, Ministry of Education/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing, Jiangsu, China.
Subseasonal monsoon dynamics, including the monsoon intraseasonal oscillation (ISO), are intensifying extreme rainfall and flooding in South Asia. These changes, driven by global warming, significantly increase flood risks in the region.
Area of Science:
- Climatology
- Hydrology
- Atmospheric Science
Background:
- Northwestern South Asia experiences increasing persistent heavy rainfall and flooding.
- Previous research focused on seasonal mean changes, overlooking subseasonal dynamics.
Purpose of the Study:
- To investigate the role of subseasonal climate dynamics in recent flood increases in Pakistan and northwest India.
- To analyze the influence of monsoon intraseasonal oscillations (ISO) on extreme rainfall and flood frequency.
Main Methods:
- Analysis of observational data on rainfall and atmospheric circulation patterns.
- Utilizing Coupled Model Intercomparison Project Phase 6 (CMIP6) projections to assess future risks.
Main Results:
- The northward-propagating monsoon ISO has strengthened and extended inland, amplifying rainfall extremes.
- A slowed southeastward-propagating mid-latitude ISO has prolonged circulation patterns conducive to heavy rainfall.
- These ISOs explain approximately 44% of the increased flood frequency, similar to mean-state changes (40%).
Conclusions:
- Subseasonal variability, particularly ISOs, is a critical driver of hydroclimatic extremes in South Asia.
- Projected intensification of ISOs under global warming will escalate flood risks in this vulnerable region.
- This study highlights an overlooked mechanism linking subseasonal dynamics to climate extremes.
More Related Videos
10:28Investigating the Relationship between Sea Surface Chlorophyll and Major Features of the South China Sea with Satellite Information
Published on: June 13, 2020
13:27Exploring the Effects of Atmospheric Forcings on Evaporation: Experimental Integration of the Atmospheric Boundary Layer and Shallow Subsurface
Published on: June 8, 2015
Related Concept Videos
What is Climate?
Responses to Drought and Flooding
Global Climate Change
Design Example: Analyzing Capacity Contours for Flood Risk Assessment
Adaptations that Reduce Water Loss
Precipitation Processes
