Hurricane annual cycle controlled by both seeds and genesis probability

Area of Science:

• Atmospheric Science
• Climate Science
• Meteorology

Background:

• Tropical cyclone (TC) climatology is crucial for societal and scientific understanding.
• The annual cycle of TC activity is a primary indicator of climate forcing and a test for climate models.
• Existing TC genesis theories often fail to explain the sharp seasonal peak observed in basins like the North Atlantic.

Purpose of the Study:

• To develop and validate a new framework for understanding tropical cyclone genesis.
• To accurately reproduce the observed annual cycle of hurricane activity in the North Atlantic.
• To assess the framework's ability to capture TC annual cycles across different ocean basins.

Main Methods:

• Applied a framework that determines TC genesis based on pre-TC synoptic disturbances (seeds) and genesis probability.
• Validated the framework against observational data and climate model simulations for the North Atlantic basin.
• Extended the analysis to evaluate TC annual cycles in other global basins.

Main Results:

• The seeds-probability framework successfully reproduces the compact hurricane season in the North Atlantic, with a sharp peak from August to October.
• The model accurately captures the abrupt increase in hurricane activity from July to August.
• The framework demonstrates consistency in predicting annual cycles across different TC basins.

Conclusions:

• The seeds-probability framework provides a more accurate representation of the hurricane annual cycle compared to existing theories.
• This framework successfully captures key aspects of TC genesis and variability, including sensitivity to climate change.
• The study highlights the essential elements of the tropical cyclone-climate connection.