Long‐term trends in tropical cyclone tracks around Korea and Japan in late summer and early fall

Lee, Min-Kyu; Cha, Dong‐Hyun; Moon, Jaekyun; Park, Jin‐Young; Jin, Chun‐Sil; Chan, Johnny C. L.

doi:10.1002/asl.939

Cited by 19 publications

(19 citation statements)

References 28 publications

(36 reference statements)

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“…SST in the WNP has increased more significantly in the mid‐latitudes than other regions in recent decades (Deser et al., 2010; Lee, Cha, et al., 2019) while being projected to substantially increase around the Korean Peninsula and Japan in future climate scenarios (Lee, Jin, et al., 2019; Murakami et al., 2011; Tsou et al., 2016). This warming pattern is similar to the negative PDO phase.…”

Section: Summary and Discussionmentioning

confidence: 99%

How Does Pacific Decadal Oscillation Affect Tropical Cyclone Activity Over Far East Asia?

Lee

Kim

Cha

et al. 2021

Geophysical Research Letters

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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 (TCm) 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 the large‐scale environments were favorable for TC activity. However, TCm and PDO were not related in August because the location of WNP subtropical high was not significantly different. In addition, large‐scale environments, which were associated with TC activity, provided more favorable conditions in September than in August.

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Section: Summary and Discussionmentioning

confidence: 99%

How Does Pacific Decadal Oscillation Affect Tropical Cyclone Activity Over Far East Asia?

Lee

Kim

Cha

et al. 2021

Geophysical Research Letters

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“…As shown in Figure 5, such wind pulses are largely associated with the extratropical cyclones over the East Asia. Previous studies have revealed that the intensity, frequency, and path of the extratropical cyclones over the East Asia were influenced by large‐scale climatic patterns, such as the global warming and Pacific decadal oscillation (Chen et al., 2019; M. Lee et al., 2019; J. Lee et al., 2020). One may, therefore, expect the causal link between the large‐scale climatic pattern and thermocline mixing.…”

Section: Discussionmentioning

confidence: 99%

“…Previous studies have revealed that the intensity, frequency, and path of the extratropical cyclones over the East Asia were influenced by large-scale climatic patterns, such as the global warming and Pacific decadal oscillation (Chen et al, 2019;M. Lee et al, 2019;J.…”

Section: Discussionmentioning

confidence: 99%

Intermittent Intense Thermocline Shear Associated With Wind‐Forced Near‐Inertial Internal Waves in a Summer Stratified Temperate Shelf Sea

et al. 2021

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Thermocline shear (i.e., velocity shear in the thermocline) lies at the heart of stratified shelf sea systems, regulating the vertical mixing and transport of mass and biogeochemical constituents. Based on year‐long moored ADCP measurements in the southern Yellow Sea (YS), the baroclinic kinetic energy and thermocline shear are investigated in this study. The rotary spectra analysis of the velocity measurements and numerical simulations with the slab model demonstrate that the wind‐forced near‐inertial internal waves (NIWs) contribute most of the baroclinic kinetic energy (50%) and thermocline shear (55%) in this stratified temperate shelf sea. The NIWs are mostly in the first two modes and are frequently generated during the warm season, associated with the presence of strong stratification and disturbances from extratropical cyclones. Most interestingly, the observed thermocline shear shows intermittent enhanced near‐inertial shear in the YS for the first time. Further analysis reveals that the thermocline shear is in the form of a clockwise rotating vector with the shear maxima (hereafter the shear spike) occurring at an angle of ∼90° to the right of the wind vector. These shear spikes, which prevail in warm seasons, are further demonstrated to be related to the wind‐shear‐alignment mechanism through comparing with a theoretical shear production model. Given the prevalence of shear spikes in warm seasons, this process is believed to have important implications in inducing thermocline mixing, which may further modulate nutrients cycling and help the maintenance of primary productivity in seasonally stratified shelf seas.

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“…In order to reduce forecast error, there has been a lot of effort to improve forecast models related to physical processes, convection, ocean feedback and resolution (Islam et al, 2015;Park et al, 2008;Soden and Held, 2006;Kendon et al, 2012). Also, the performance of the forecast models has been improved by techniques related to initial condition (Kwon and Cheong, 2010;Cha et al, 2013), forcing data (Kang et al, 2005;Moon et al, 2019) and model output (Piani et al, 2010;Dosio and Paruolo, 2011).…”

Section: Introductionmentioning

confidence: 99%

Improvement of Tropical Cyclone Track Forecast over the Western North Pacific Using a Machine Learning Method

Kim¹,

Cha²,

Im³

2020

Preprint

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<p>&#160;The accurate tropical cyclone (TC) track forecast is necessary to mitigate and prepare significant damage. TC has been predicted by the numerical models, statistical models, and machine learning methods in previous researches. However, those models are separately used for TC track forecast, and historical data with satellite images were used as input variables for machine learning without forecast data from numerical models. In this study, we corrected the TC track forecast of a numerical model by artificial neural network (ANN). TCs that occurred from 2006 to 2015 over the western North Pacific were hindcasted by the Weather Research and Forecasting (WRF) model, and all categories of TCs except for tropical depression (i.e., tropical storm, severe tropical storm, and typhoon) from June to November were included in this study. We evaluated the performance of TC track forecast in terms of duration, translation speed, and direction compared with the best track data. The simulated positions of TCs at 24-hour, 48-hour, and 72-hour forecast lead time were used as variables for training and testing ANN. To optimize the number of neurons in ANN, simulated TCs were divided into two parts; TCs in 2006-2014 for ANN optimization and those in 2015 for a blind test. Also, the output selection method based on the forecast error of the WRF was applied to exclude the outlier of ANN results. By applying the output selection, the forecast error of ANN was further reduced than that of the WRF. As a result, ANN with the output selection method could improve TC track forecast by about 15% compared to the WRF. Also, the effect of ANN tended to increase when the forecast error of the WRF was large. The output selection method was particularly effective by excluding outliers of ANN results when the forecast error of the WRF was small.</p> <p>&#8251; This research was supported by Next-Generation Information Computing Development Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Science, ICT (NRF-2016M3C4A7952637).</p>

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Long‐term trends in tropical cyclone tracks around Korea and Japan in late summer and early fall

Cited by 19 publications

References 28 publications

How Does Pacific Decadal Oscillation Affect Tropical Cyclone Activity Over Far East Asia?

How Does Pacific Decadal Oscillation Affect Tropical Cyclone Activity Over Far East Asia?

Intermittent Intense Thermocline Shear Associated With Wind‐Forced Near‐Inertial Internal Waves in a Summer Stratified Temperate Shelf Sea

Improvement of Tropical Cyclone Track Forecast over the Western North Pacific Using a Machine Learning Method

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