Dong‐Hyun Cha

Abstract To improve the initial conditions of tropical cyclone (TC) forecast models, a dynamical initialization (DI) scheme using cycle runs is developed and implemented into a real-time forecast system for northwest Pacific TCs based on the Weather Research and Forecasting (WRF) Model. In this scheme, cycle runs with a 6-h window before the initial forecast time are repeatedly conducted to spin up the axisymmetric component of the TC vortex until the model TC intensity is comparable to the obse

[1] This study examines simulated typhoon sensitivities to spectral nudging (SN) to investigate the effects on values added by regional climate models, which are not properly resolved by low-resolution global models. SN is suitably modified to mitigate its negative effects while maintaining the positive effects, and the effects of the modified SN are investigated through seasonal simulations. In the sensitivity experiments to nudging intervals of SN, the tracks of simulated typhoons are improved

In this study, the systematic errors in regional climate simulation of 28‐year summer monsoon over East Asia and the western North Pacific (WNP) and the impact of the spectral nudging technique (SNT) on the reduction of the systematic errors are investigated. The experiment in which the SNT is not applied (the CLT run) has large systematic errors in seasonal mean climatology such as overestimated precipitation, weakened subtropical high, and enhanced low‐level southwesterly over the subtropical

Abstract Because of global warming and abnormal climate change, record‐breaking heat wave events have been increasing. Therefore, it is necessary to analyze and predict the mechanisms for generating and developing heat waves. In this study, the impacts of synoptic and local factors on heat waves over the southeastern region of South Korea in 2015 are investigated. First, Heat wave events for 1980–2016 defined by spatiotemporal criteria are classified into three clusters using the K‐means cluster

ABSTRACT In this study, the regional climate of the Korean Peninsula is dynamically downscaled using a high‐resolution regional climate model forced by two representative concentration pathway scenarios of Hadley Centre Global Environmental Model version 2‐Atmosphere and Ocean (HadGEM2‐AO) using multiple regional climate models. Changes in extreme precipitation indices are investigated. Through the evaluation of the present climate, a multi‐model ensemble reasonably reproduces the long‐term clim

Abstract Regional models often face a chronic problem caused by inconsistencies between simulated model fields and large‐scale forcing data, which could limit predictability of regional models. Spectral nudging is a technique which can ameliorate this issue by providing large‐scale forcing in the regional model interior. In this study, spectral nudging was applied to tropical cyclone (TC) track and intensity forecasts, and its effects were investigated using a high‐resolution regional model. Cas

Impacts of coupled air–sea interaction and large-scale nudging were examined through regional climate simulation of the East Asian summer monsoon (EASM). A slab ocean model (SOM) was coupled with a regional climate model (RCM) to investigate the impact of two-way air–sea interaction, and the spectral nudging was applied to examine the effect of large-scale nudging. The control run without coupled air–sea interaction and large-scale nudging had significantly large systematic errors in simulated o

Abstract In high‐resolution numerical modeling, cloud microphysics schemes can affect the forecasting of tropical cyclones (TCs) by controlling the phase changes of water. The simulated TC characteristics such as motion, intensity, and structure can change depending on the number of hydrometeors used in these schemes. In this study, we investigate the sensitivity of real‐time track and intensity forecasts of TCs to cloud microphysics schemes using the Weather Research and Forecasting (WRF) model

Abstract We investigated the relationship between tropical cyclones (TCs) and the Pacific Decadal Oscillation (PDO) over the western North Pacific (WNP) during 1982–2018, focusing on an area surrounding the Korean Peninsula and Japan. The frequency of TCs passing through this area (TC m ) in the negative PDO phase was approximately 50% higher than that in the positive phase in September. Higher TC track density was observed around the Korean Peninsula and Japan in the negative PDO phase because

Abstract This study investigates long‐term trends in tropical cyclones (TCs) over the extratropical western North Pacific (WNP) over a period of 35 years (1982–2016). The area analyzed extended across 30–45°N and 120–150°E, including the regions of Korea and Japan that were seriously affected by TCs. The northward migration of TCs over the WNP to the mid‐latitudes showed a sharp increase in early fall. In addition, the duration of TCs over the WNP that migrated northwards showed an increase, spe

Abstract This study evaluated tropical cyclone (TC) activity simulated by two regional climate models (RCMs) incorporated in the Coordinated Regional Climate Downscaling Experiment (CORDEX) framework with two different horizontal resolutions. Evaluation experiments with two RCMs (RegCM4 and MM5) forced by reanalysis data were conducted over the CORDEX-East Asia domain for phases I and II. The main difference between phases I and II is horizontal resolution (50 and 25 km). The 20-yr (1989–2008) m