Hysteresis Behaviors in East Asian Extreme Precipitation Frequency to CO<sub>2</sub> Pathway
Seo‐Young Jo, Min‐Gyu Seong, Seung‐Ki Min, Jong‐Seong Kug, Sang‐Wook Yeh, Soon‐Il An, Seok‐Woo Son, Jongsoo Shin
Abstract
Abstract Understanding regional hydro‐climatic extreme responses to CO 2 pathways is fundamental to climate change mitigation and adaptation. This study evaluates responses of extreme precipitation frequency (R30mm: days with precipitation ≥30 mm) over East Asia to idealized CO 2 forcing using the Community Earth System Model (CESM1). Under a symmetric increase (ramp‐up, +1% per year until quadrupling level) and decrease (ramp‐down, about −1% per year back to the present level) of CO 2 concentrations, East Asian R30mm shows an asymmetric response with higher frequency during the ramp‐down period. This hysteresis behavior is found to be due to a northwestward propagating wave response to the El Niño‐like warming, which induces a three‐cell (positive‐negative‐positive) R30mm difference pattern from central equatorial Pacific to East Asia. Monthly analysis further reveals that this asymmetry has a seasonal locking, occurring during July–September only, constrained by the background precipitation climatology over the sub‐tropical western Pacific.