Overview
This lecture, part of a webinar series on monsoons, focuses on the Asian-Australian Monsoon, its research communities, climate change impacts, operational forecasting, and communication challenges between science and stakeholders.
Introduction to the Asian-Australian Monsoon
- The Asian-Australian Monsoon region covers about a third of global tropics and subtropics, affecting over 3 billion people.
- It is divided into East Asian, South Asian, Western/North Pacific, and Indonesian-Australian monsoons, each with distinct summer and winter seasons.
- A regional working group with diverse scientists promotes collaboration, research, forecasting, and stakeholder engagement.
Indian Monsoon and Climate Change Impacts
- Climate change increases frequency and intensity of extreme rainfall events in Central India, while reducing small and medium rainfall events.
- The intensity of the heaviest seasonal rainfalls has risen by about 40% over 50 years.
- Seasonal mean monsoon rainfall increases roughly 3% per degree of global temperature rise, but regional differences exist.
- Central India sees increased rainfall; Northeast India observes a decrease in average rainfall but an increase in extreme events.
- The spatial rainfall distribution is shifting westward, with western regions becoming wetter under climate change.
Predictability and Model Challenges
- Current models struggle with biases and uncertainty in projecting monsoon rainfall.
- ENSO explains only about 35% of Indian monsoon variability; other sources of predictability need identification.
- High-resolution models are needed for better simulation of extremes and synoptic-scale disturbances.
- Process-based verification and collaboration across disciplines are essential for model improvement.
Australian Monsoon: Operational View
- Northern Australia’s cattle industry and biodiversity rely on the summer monsoon; onset timing is crucial.
- Multiple definitions exist for monsoon onset, based on wind, rainfall, or outgoing longwave radiation.
- The Madden-Julian Oscillation (MJO) and other tropical waves drive monsoon bursts and breaks.
- The community is highly engaged and depends on products forecasting rainfall onset, rainfall bursts, tropical cyclones, and seasonal outlooks.
- Forecast skill for summer rainfall remains limited; external events (e.g., volcanic eruptions) can disrupt expected patterns.
Science Communication and Stakeholder Engagement
- Monsoon variability is complex; communicating scientific uncertainty and probabilistic forecasts to users is critical.
- Stakeholders, such as farmers, value explanations of climate drivers and probabilistic information for decision-making.
- Collaboration between model developers, operational forecasters, and end-users improves usefulness and adoption of climate products.
Key Terms & Definitions
- Monsoon — Seasonal wind and rainfall patterns affecting large regions.
- ENSO (El Niño–Southern Oscillation) — Climate pattern involving temperature changes in the Pacific Ocean, influencing global weather.
- Madden-Julian Oscillation (MJO) — Tropical atmospheric wave affecting rainfall on 30–60 day timescales.
- Synoptic Disturbances — Short-lived, large-scale weather systems, such as cyclones or depressions.
- Extreme Events — Unusually intense weather events, like heavy rainfall or droughts.
- Process-Based Verification — Model evaluation approach focused on comparing simulated and observed physical processes.
Action Items / Next Steps
- Review posted webinar video and Q&A for further insights.
- Follow updates from the Monsoon working group and participate in future webinars.
- Explore regional monsoon forecast products and practice interpreting probabilistic forecasts.
- Stay engaged with ongoing research and model improvement initiatives.