Yuchen Wang 교수

Abstract. Eastern China (27–41∘ N, 110–123∘ E) is heavily polluted by nitrogen dioxide (NO2), particulate matter with aerodynamic diameter below 2.5 µm (PM2.5), and other air pollutants. These pollutants vary on a variety of temporal and spatial scales, with many temporal scales that are nonperiodic and nonstationary, challenging proper quantitative characterization and visualization. This study uses a newly compiled EOF–EEMD analysis visualization package to evaluate the spatiotemporal variabil

Abstract We propose a new tsunami data assimilation approach based on Green's functions to reduce the computation time for tsunami early warning. Green's Function‐based Tsunami Data Assimilation (GFTDA) forecasts the waveforms at points of interest (PoIs) by superposition of Green's functions between observation stations and PoIs. Unlike the previous assimilation approach, GFTDA does not require the calculation of the tsunami wavefield for the whole region during the assimilation process, becaus

Abstract The Eastern Mediterranean Basin (EMB) is under the threat of tsunami events triggered by various causes including earthquakes and landslides. We propose a deployment of Offshore Bottom Pressure Gauges (OBPGs) around Crete Island, which would enable tsunami early warning by data assimilation for disaster mitigation. Our OBPG network consists of 12 gauges distributed around Crete Island, with a 100‐km interval, based on three criteria to select the locations. The station network must have

Abstract The tsunami resonance leads to the amplification of wave heights and extends the duration of wave activity. For tsunami warning and coastal planning, it is important to understand resonance behavior. We characterized the tsunami resonance of trans‐Pacific events in the bays and continental shelves of Japan, focusing on the Hokkaido and Sanriku regions. We considered five tsunami events with sources in the Peru–Chile subduction zone and the Alaska–Aleutian subduction zone. Spectral analy

VFA 80 cm2 effectively identified carotid atherosclerosis for both lean and obese individuals in middle-aged Chinese men.

Abstract The 2016 Fukushima earthquake (M 7.4) generated a moderate tsunami, which was recorded by the offshore pressure gauges of the Seafloor Observation Network for Earthquakes and Tsunamis (S-net). We used 28 S-net pressure gauge records for tsunami data assimilation and forecasted the tsunami waveforms at four tide gauges on the Sanriku coast. The S-net raw records were processed using two different methods. In the first method, we removed the tidal components by polynomial fitting and appl

Abstract The tsunami data assimilation method enables tsunami forecasting directly from observations, without the need of estimating tsunami sources. However, it requires a dense observation network to produce desirable results. Here we propose a modified method of tsunami data assimilation for regions with a sparse observation network. The method utilizes interpolated waveforms at virtual stations. The tsunami waveforms at the virtual stations between two existing observation stations are estim

Abstract A tsunami was triggered in the North Pacific Ocean by the 2021 Alaska earthquake (M 8.2) on July 29. We studied the source properties and resonance characteristics of the tsunami event using observed records from offshore tsunameters and coastal tide gauges as well as numerical simulation. Spectral analyses were conducted on records at tsunameters and tide gauges. We reconstructed the tsunami source spectrum by calculating the ratio of tsunami spectra to the background spectra of these

Selective laser sintering is used to prepare components from a kind of blended powder of polyamide 12 (PA12) and organically modified rectorite (OREC). The effects of OREC on the sintering parameters and mechanical properties of the sintered specimens are investigated. The results show that the laser power needed for sintering decreases greatly and the mechanical properties of the sintered specimens are imprved considerbly with the addition of OREC. The differential scanning calorimetry result s

Abstract Abnormal volcanic earthquakes occurring near the volcanic island of Torishima, south of Japan, sometimes generate relatively larger tsunamis compared to the seismic magnitudes. They have a non‐double‐couple focal mechanism known as compensated linear vector dipole. The unusual earthquake source mechanism poses difficulties in traditional tsunami forecasting method based on seismic parameters. Tsunami data assimilation, a method of tsunami forecast using offshore tsunami observation data

Abstract We propose a method of real-time tsunami detection using ensemble empirical mode decomposition (EEMD). EEMD decomposes the time series into a set of intrinsic mode functions adaptively. The tsunami signals of ocean-bottom pressure gauges (OBPGs) are automatically separated from the tidal signals, seismic signals, as well as background noise. Unlike the traditional tsunami detection methods, our algorithm does not need to make a prediction of tides. The application to the actual data of

Abstract High‐frequency (HF) radar monitors the sea surface current velocity and provides information for tsunami early warning. SeaSondeR, an HF ocean radar system in the eastern Tsugaru Strait, Japan, measured the tsunami‐induced current velocity during the 2022 Tonga volcanic tsunami. As an air‐coupled tsunami, the generating mechanism was complex, making it difficult to predict coastal tsunamis using traditional early warning methods. We adopted the tsunami data assimilation (DA) approach, w

Earthquakes occurring in the Ryukyu Trench, Nankai Trough, and Japan Trench can trigger tsunamis, affecting Hangzhou Bay, China. The 2011 Tohoku tsunami reached the east China coast and resulted in prolonged oscillations in Hangzhou Bay. We used this event as an example and studied the resonance behavior in Hangzhou Bay by spectral and modal analyses. We simulated the wavefield of the 2011 Tohoku tsunami and validated the modeling results using the tide gauge records. The spectral analysis based