Warm Advection as a Cause for Extreme Heat Event in North China

Abstract

Extreme heat events (EHEs) often hit North China, resulting in significant losses. The devastating EHE in the 1743 summer, marked as the highest temperature in the past 300 years, led to ∼11,000 fatalities. These historical EHEs prompt us to explore potential mechanisms beyond anthropogenic influences. We employ the Norwegian Earth System Model here to simulate the past millennium climate and then dynamically downscale the July 1743 event using the Weather Research and Forecasting Model. The successful simulation of warming in North China, although it has been a fortunate outcome, is supported by tree-ring records, providing a compelling case study for the event. Through composite and case analyses, we discover a connection between EHEs and active Northeast China Vortexes (NCVs) which induce warm advection, consequently heating the lower atmosphere. Reanalysis further confirms the connection in the modern era. Our study suggests modeling past EHEs, while challenging, is indeed feasible.