Meteorological characteristics of line-shaped rainbands in northern Japan and its surrounding seas under climate change

Abstract

In recent years, line-shaped rainbands (LRBs) have increased in Hokkaido, Japan. LRBs caused several flood disasters historically, thus the weather patterns that cause them need to be investigated. This study aimed to understand statistically the relationship between LRBs and weather patterns during the summer months under climate change conditions. Our study investigates the link between LRBs and weather patterns in Hokkaido during July and August, using historical and climate prediction models. With a 2°/4° global temperature rise, LRB occurrences in this region increase by approximately 1.51/2.07 times. The highest occurrences of LRBs correlate with increased water vapor flux from the south and positive pressure anomalies over the Pacific Ocean. Three main weather patterns contribute significantly to LRBs: (1) a nearby low-pressure system, (2) a strengthening Pacific High frontal pattern, and (3) approaching or landing typhoons in Hokkaido. These patterns double the LRB occurrence probability, a trait observed across past and projected climates (+2K and +4K experiments). These are important insights for future flood risk management. HIGHLIGHTS Integrative technical approach in hydroinformatics proposed for the first time.; The novel framework was introduced for the analysis of massive climate data.; Important new insights into line-shaped rainbands are provided.; Important insights into the effects of climate change are provided.; Significant enhancement in understanding summer meteorological fields contributing to heavy rainfall.;

Keywords

• climate change
• heavy rainfall
• line-shaped rainbands
• mesoscale
• northern japan
• self-organizing maps