Effects Of Typhoons Research Articles

A meso- to micro-scale coupled model under typhoon conditions considering vortex structure and coriolis effect for wind farms

Accurate simulations of typhoon-induced wind speeds on wind farms are crucial for the refined assessment of typhoon risks in wind turbines. Southeastern coastal area in China is rich in wind resources but is also severely threatened by typhoons. As an extremely destructive weather system with complex structures, the refined near-surface wind fields of typhoons are difficult to simulate by meso-scale models for risk assessment. Therefore, a coupled meso- and micro-scale model under typhoon conditions is proposed to simulate typhoon-induced winds on a wind farm. The Coriolis force is considered in the coupled model to reflect the rotating effect of typhoons caused by the vortex structure. A coupling algorithm based on objective analysis is proposed to construct boundary conditions at the coupling interface, to consider the variation of inflow variables in the vertical and cross-wind directions. Model constants of the two-equation turbulence model are calibrated based on typhoon field observations, to more reasonably simulate typhoons. A validation study is conducted, and the results show that the maximum wind speed on the wind farm simulated by the coupled model exhibits an increased accuracy compared with that of the meso-scale model, where the absolute error decreases by 34%.

Consecutive Northward Super Typhoons Induced Extreme Ozone Pollution Events in Eastern China

Typhoons are one of the most important weather systems that can cause severe ozone (O3) pollution in eastern China. While the effects of individual typhoons on O3 concentrations have been extensively studied, the effects of consecutive northward typhoons and the underlying mechanisms remain unclear, partly due to the complex processes involved. Here, Typhoons Maysak and Haishen, two consecutive northward typhoons in 2020, are selected to investigate their impact on the O3 pollution in eastern China. The results show that consecutive northward typhoons not only produced and maintained meteorological conditions conducive to O3 generation (e.g., elevated temperatures and intensified solar radiation), but also facilitated local accumulation and cross-regional transport of O3. These factors jointly led to a 30% increase in O3 concentration in eastern China with a prolonged period of O3 pollution. Our work underscores the significance of complex meteorological conditions in O3 pollution occurrences during extreme weather events, advancing our understanding of how consecutive northward typhoons affect air quality.

Effect of atmospheric response induced by preceding typhoon on movement of subsequent typhoon over Northwestern Pacific

This study investigates the atmospheric interactions between two closely located typhoons in 2019. Typhoons in the Western Pacific significantly impact Eastern and Southeastern Asian countries, leading to various damages. As global warming is expected to increase typhoon intensity, accurate track forecasting becomes crucial for coastal disaster management. Despite the existing knowledge about the influence of typhoon activities on the atmospheric background, limited research addresses the atmospheric response between two typhoons. The study focuses on the cases of LEKIMA and KROSA, occurring simultaneously in 2019, and utilizes the Weather Research and Forecasting (WRF) model for simulations. The experimental setup involves comparing two scenarios: one with both typhoons and one with LEKIMA removed. Results reveal LEKIMA-induced distinctive atmospheric responses, including the closure of the western North Pacific subtropical high (WNPSH) boundary and the formulation of a wave train, influencing KROSA’s stagnation. The absence of LEKIMA allows KROSA to move more freely along the steering flow. Furthermore, the study highlights the potential of atmospheric models for understanding typhoon effects at regional to mesoscale levels. A comprehensive analysis of similar cases could enhance typhoon predictions, contributing to better damage mitigation strategies.

Revealing the Effect of Typhoons on the Stability of Residual Soil Slope by Wind Tunnel Test

Typhoon-induced slope failure is one of the most important geological hazards in coastal areas. However, the specific influence of typhoons on the stability of residual soil slopes still remains an open issue. In this study, the Feiyunjiang catchment in Zhejiang Province of SE China was chosen as the study area, and a downscaling physical model of residual soil slopes in the region was used to carry out the wind tunnel test. Our aim was to answer the question, How does the vegetation on the slope and slope stability respond during a typhoon event? For this purpose, multiple aspects were monitored and observed under four different wind speeds (8.3 m/s, 10.3 m/s, 13.3 m/s, and 17 m/s), including vegetation damage on the slope, macrocracks on the slope surface, wind pressure, wind load, permeability coefficient of the soil layer, and slope stability. The results showed that the plants on the slope could restore to their original states when the wind speeds ranged from 8.3 m/s to 13.3 m/s, but were damaged to the point of toppling when the wind speed increased to 17 m/s. Meanwhile, evident cracks were observed on the ground under this condition, which caused a sharp increase in the soil permeability coefficient, from 1.06 × 10−5 m/s to 6.06 × 10−4 m/s. The monitored wind pressures were larger at the canopy than that at the trunk for most of the trees, and generally larger at the crown of the slope compared with the toe of the slope. Regarding the wind load to the slope ground, the total value increased significantly, from 35.4 N under a wind speed of 8.3 m/s to 166.5 N under a wind speed of 17 m/s. However, the wind load presented different vector directions at different sections of the slope. The quantitative assessment of slope stability considering the wind load effect revealed that the safety factor decreased by 0.123 and 0.1 under the natural state and saturated state, respectively, from no wind to a 17 m/s strong wind. Overall, the present results explained the mechanism of slope failure during typhoon events, which provided theoretical reference for revealing the characteristics of residual soil slope stability under typhoon conditions.

Multi-scale simulation of typhoon wind field at building scale utilizing mesoscale model with nested large eddy simulation

Based on the mesoscale WRF (Weather Research Forecast) and LES (Large Eddy Simulation), an integrated numerical simulation framework aiming to resolve typhoon wind fields around urban building blocks has been developed. The holistic multi-scale simulation spans four scales: macroscale (∼1000 km), mesoscale (∼100 km), microscale (∼1 km), and building scale (0.1–100m). By interactively sharing the meteorological data among different scales, this simulation framework addressed the challenge of downscaling typhoon effects in urban environments. Typhoon weather reanalysis and urban wind field simulation were conducted by the WRF model with nested computational domains incorporating high-resolution topography data. For the downscaled LES model with urban buildings, the wind profiles produced by the WRF model were used at the interface with provided turbulent fluctuations in the flow. K11 building is a 270-m-tall building located in a densely built-up area of Hong Kong. Wind velocity and pressure fields surrounding the K11 building in Hong Kong during Typhoon Kammuri were obtained by the proposed framework, and the simulation results were validated by comparing with the meteorological data and full-scale measurements at the top of the K11 building. The interactions of the wind fields and building clusters resulting in vortex shedding, separation, and channeling effects have been resolved at high resolutions. Probabilistic distributions and higher-order statistics of wind pressure, i.e., skewness and kurtosis, were presented to highlight non-Gaussian characteristics of the simulated local wind pressure on the K11 building. Based on the simulated wind pressure, wind-induced vibration of the K11 building during the typhoon was analyzed and compared to the measurements.

Typhoon strikes, political costs and earnings management

AbstractThis study examines how firms in typhoon‐prone areas respond to the political costs of typhoon strikes. We found that such firms tend to engage in downward earnings management after a typhoon strike. Various robustness tests support our findings: cross‐sectional variation tests indicate that this tendency is strong in cities with high governmental intervention and incentives for political leaders and in firms with high political connections and visibility. Further analysis reveals that typhoon strikes enhance earnings management by intensifying fiscal pressure. Finally, this study provides a precise evaluation of the adverse effects of typhoons and complements the existing literature on the political cost hypothesis.

Contrasting carbon cycling in the benthic food webs between a river-fed, high-energy canyon and an upper continental slope

Abstract. The Gaoping Submarine Canyon (GPSC) off southwest Taiwan has been extensively studied due to its unique geology, its role in transferring terrestrial material to the deep sea, and its diverse biological communities. However, there is a lack of understanding of carbon cycling across the sediment–water interface in the canyon. This study aims to fill the gap by utilizing the field data collected between 2014 and 2020 and a linear inverse model (LIM) to reconstruct the benthic food web (i.e., carbon flows through different stocks) in the head of GPSC and the upper Gaoping slope (GS). The biotic and abiotic organic carbon (OC) stocks were significantly higher on the slope than in the canyon, except for the bacteria stock. The sediment oxygen utilization was similar between the two habitats, but the magnitude and distribution of the OC flow in the food web were distinctively different. Despite a significant input flux of ∼ 2020 mg C m−2 d−1 in the canyon, 84 % of the carbon flux exited the system, while 12 % was buried. On the slope, 84 % of the OC input (∼ 109 mg C m−2 d−1) was buried, and only 7 % exited the system. Bacteria processes play a major role in the carbon fluxes within the canyon. In contrast, the food web in the upper slope exhibited stronger interactions among metazoans, indicated by higher fluxes between meiofauna and macrofauna compartments. Network indices based on the LIM outputs showed that the canyon head had higher total system throughput (T..) and total system throughflow (TST), indicating greater energy flowing through the system. In contrast, the slope had a significantly higher Finn cycling index (FCI), average mutual information (AMI), and longer OC turnover time, suggesting a relatively more stable ecosystem with higher energy recycling. Due to sampling limitations, the present study only represents the benthic food web during the “dry” period. By integrating the field data into a food web model, this study provides valuable insight into the fates of OC cycling in an active submarine canyon, focusing on the often overlooked benthic communities. Future studies should include “wet” period sampling to reveal the effects of typhoons and monsoon rainfalls on OC cycling.

Remote Effects of double Typhoons on Record-breaking Rainfall: A case Study in North China

During 18–22 July 2021, an extreme precipitation event occurred in Henan, China, with maximum daily precipitation reached 657 mm, broking their historical records and resulting in severe disaster. This heavy rainstorm occurred with the background of two typhoon (In-fa and Cempaka) activities, but resent studies have only considered the effects of individual typhoons, ignoring their combined effects. The Dynamic Recycling Model and Weather Research and Forecasting Model were applied to investigate the contributions of two typhoons on water vapor transportation. Two transportation paths were determined: the eastern path for In-fa and the southwestern path for Cempaka. These paths contributed up to 78% of the total water vapor over Henan. Two typhoons jointly led to extreme precipitation, and Cempaka showed greater impact than In-fa on the vapor transportation. The precipitation was 39.0% of that in the control test when only Cempaka existed and 34.4% when only considering In-fa. The sensitivity results also indicate that Cempaka mainly induced the early stage of precipitation, while In-fa controlled the later stage. In addition to the effect of water vapor transportation, In-fa also influenced the local atmospheric stability. The pseudo equivalent potential temperature near the surface was 6 K higher when only In-fa existed relative to the scenario in which no typhoon was considered, indicating that In-fa strengthened the convective instability. Therefore, both Cempaka and In-fa contributed to this extreme precipitation event. Cempaka transferred more water vapor than In-fa, and In-fa acted to increase the instability. Their joint contribution amplified the precipitation intensity beyond the cumulative impact of individual effects.

Effects of typhoons on primary production and dissolved oxygen in the East China Sea

Previous investigations confirm that typhoons deliver both dissolved oxygen and nutrient sources via promoting vertical/lateral exchanges between water masses. The former one replenishes oxygen for the bottom water and prevents persistent oxygen depletion, while the latter one facilitates primary production and subsequent subsurface oxygen consumption. However, it is left unknown if typhoons ultimately result in net gain or loss of dissolved oxygen during the passage. Tropical cyclone information, satellite observations, and numerical simulations were used to investigate the response of primary production and dissolved oxygen dynamics to typhoons. Results imply that both typhoon intensity, and distance between typhoon track and the Changjiang estuary control the magnitude of responses in primary production, air-sea oxygen flux, advection-induced oxygen variation, and oxygen consumption variation. The model-based oxygen budget analysis indicated that oxygen content increased after the passage of all typhoons occurred between 2011-2020. The findings in this study suggest that typhoons ultimately result in net gain of oxygen. The increased strength and frequency of typhoon in the warming future would play an important role in counteracting deoxygenation, which is likely to slow down the pace of deterioration of the seasonal hypoxia in this region.

Simulating the impact of typhoons on air‐sea CO2 fluxes on the northern coastal area of the South China Sea

The South China Sea is a typhoon-prone region, and previous studies have shown that typhoons have significant impacts on air-sea CO2 fluxes. However, the effect of typhoons on the northern coastal area of the South China Sea is not well understood owing to limited observational data. In this study, we used a coupled model to simulate the impact of four typhoons (Hato, Mangkhut, Nida, and Merbok) on the partial pressure of CO2 in seawater (pCO2sea) and the CO2 fluxes in this area. Our results show that the coupled model effectively reproduces the spatial pattern of pCO2sea in this region. The response of pCO2sea to typhoons was determined by typhoon-induced vertical mixing and coastal upwelling, along with initial oceanic conditions. Typhoon Nida caused a decrease in pCO2sea with Total Alkalinity and Sea Surface Temperature being the primary factors. However, typhoons Hato, Mangkhut, and Merbok caused an increase in pCO2sea with Dissolved Inorganic Carbon playing a more prominent role. The average CO2 fluxes during the passage were approximately 6–14 times higher than those before typhoon passage. These results enhance our understanding of the effect of typhoons on air-sea CO2 fluxes over the northern coastal area of the South China Sea.

Silvicultural Management Strategies: A Determinant for a Successful NGP Plantation in Northern Isabela, Philippines

The National Greening Program is the most extensive reforestation program in the Philippines. It aimed for climate change mitigation, biodiversity conservation, and food security. This paper provides initial information on the performance of NGP in Northern Isabela, focusing on the general information of the plantation site, the participation of stakeholders, and the implementation of selected forestry management strategies. Three sites were considered, which are located in Delfin Albano, Cabagan, and San Pablo, Isabela. Findings revealed that the plantation sites were grasslands and previously were of corn plantations. Yemane is the common species planted in the three study sites because it is less susceptible to the effects of drought, fire, pests, diseases, and typhoons, according to the implementers. Other tree species planted in Delfin Albano are teak, kadamba, acacia, and mahogany. It was further validated during the field site visit and inspection that the above-mentioned tree species have 100% survival because the implementers were equipped with knowledge on some silvicultural strategies for maintaining the plantation. Implementers considered the period of planting, the ideal size of seedlings, the proper spacing, fertilization requirements, and intermediate treatments for sanitation. Nevertheless, it is recommended to all plantations that the implementers should integrate agroforestry crops in collaboration with the Department of Agriculture. Finally, since the DENR was tasked with the monitoring and validation of the performance of the program, the DENR should also partner with various research institutions, including academic institutions, to assess the progress of the NGP for enhancement.

Daily impact of the simultaneous passage of binary typhoons on sea surface chlorophyll-a concentration dynamics in the Northwestern Pacific

Typhoons are recognized as one of the most destructive meteorological phenomena, exerting significant influences on marine ecosystems. Sea surface chlorophyll-a concentration (CHL)an essential indicator of phytoplankton biomass, can be utilized to characterize the disturbances of typhoons on the marine ecosystem. However, it is challenging to investigate this impact at a daily scale due to the missing CHL remote sensing data caused by cloud cover. Given that concurrent passing typhoons may interact with CHL, this study analyzes the effect of the simultaneous passage of binary typhoons Tembin and Bolaven on CHL by using daily CHL reconstruction data, and investigates the role of ocean environmental factors in driving the dynamics of CHL, including sea surface temperature (SST), mixed layer depth (MLD), and sea surface height anomaly (SSHA). The results show that typhoons Tembin and Bolaven increase CHL with the maximum increment of ∼3.2 mg∙m−3 during 4–6 days after typhoons passage. The maximum change areas of CHL are distributed near the intersection of typhoon track of (32°N, 125.2°E), corresponding to the regions of greater variation in SST and MLD. During 15 days before and after typhoons (i.e., from 15 August to 15 September 2012), SST is negatively correlated with CHL (the correlation coefficient of −0.85) and MLD is positively correlated with CHL (the correlation coefficient of −0.80). SST immediately declines after typhoons with a maximum cooling of 7.8 deg. C, showing the decreased SST from ∼28 deg. C to ∼23 deg. C can promote phytoplankton growth. MLD deepens from 10 m to >25 m caused by typhoon-induced strong winds, allowing more nutrients to be transported from the subsurface layer to the euphotic layer for phytoplankton blooms. Furthermore, oceanic eddies captured by SSHA change from cyclonic to anticyclonic eddies accompanied by the beginning of CHL increases, and the largest CHL increases correspond to the distribution of pre-existing cyclonic eddies. It suggests that Tembin and Boravin promote phytoplankton growth to increase CHL by enhancing vertical mixing and upwelling to transport nutrients to the sea surface. These findings inspire us to rethink the daily effects of typhoons on CHL, with critical importance for predicting and managing the ecological consequences of typhoons in the ocean.

Harvested Spartina area performs better than native Scirpus in sedimentation and carbon preservation under storm surge

Typhoons pose threats to coastal wetlands, but the impacts on carbon stocks remain unclear. This study investigated typhoon effects on salt marsh carbon pools with different vegetation covers (harvested Spartina alterniflora, native Scirpusmariqueter, bare mudflat) in the Yangtze River estuary.During Typhoon Muifa (September 2022), significant erosion occurred in the Scirpus area while the harvested Spartina area experienced sediment deposition, indicating its stronger coastal protection capacity. Grain size analysis validated the geomorphic changes. The harvested Spartina area also captured coarser sediments from the mudflat. Wave data showed the amplified hydrodynamics during typhoons can transport more sediment into marshes.In the Scirpus area, surface sediments (0–15 cm) lost 43% organic carbon and 73% belowground biomass due to erosion. The deposited sediments after typhoons lacked the original high carbon content. In contrast, harvested Spartina areas maintained carbon levels despite intense hydrodynamics. The bare mudflat lost 43% total carbon after experiencing substantial erosion.This study demonstrates harvested Spartina areas effectively mitigated carbon loss and even facilitated carbon sequestration through enhanced sediment trapping during typhoons. With intensifying storm surges, seasonal harvesting of Spartina could balance coastal protection and ecological functions better than complete removal. The carbon sink capacity of sediments with native vegetation is vulnerable to typhoons due to limited resilience. Harnessing bio-geomorphic feedbacks is crucial for preserving blue carbon storage facing climate change.

Sea Surface pCO2 Response to Typhoon “Wind Pump” and Kuroshio Intrusion in the Northeastern South China Sea

The Luzon Strait (LS) is a key region for estimating carbon sources and sinks in the South China Sea (SCS) and is highly influenced by the Kuroshio Current (KC) and typhoons. Understanding the variations in the sea surface partial pressure of carbon dioxide (pCO2-sw) under the combined effects of typhoons and KC in this region is crucial for estimating local and regional changes in ocean carbon flux. Based on valuable in situ pCO2-sw and remote sensing data, this study aimed to reveal the temporal variations and the physical mechanisms of pCO2-sw variations under the comprehensive effects of both typhoons and Kuroshio Intrusion (KI) in the LS. One week after the passage of the tropical cyclone (TC) Nanmadol, the concentration in the pCO2-sw and the influencing mechanisms varied in three different regions (W1–W3) on Transect A (120°E). In the region dominated by SCS waters (W1), the average pCO2-sw increased by 5.1 μatm after TC, which was mainly due to the TC “Wind Pump” inducing strong vertical mixing, which brought dissolved inorganic carbon (DIC)-rich deeper water up to the surface. In the region affected by KC (W2 and W3), pCO2-sw decreased after the TC (−8.2 μatm and −1.8 μatm, respectively) with TC-enhanced KI because the invasion of lower pCO2-sw of Kuroshio waters inhibited the TC-induced upwelling. More significant TC-induced upwelling (W3) would alleviate the decrease in pCO2-sw caused by the TC-enhanced KI. This study is a rare case providing a better understanding of the variations in pCO2-sw under TC-enhanced KI, which provides support for regional climate change prediction and carbon flux estimation in the western boundary current regions.

Life cycle carbon footprint accounting of an offshore wind farm in Southeast China—Simplified models and carbon benchmarks for typhoons

Offshore wind farms are fast-spreading off the southeast coast of China to achieve carbon neutrality by 2060. However, unfavorable weather conditions in Southeast China (e.g. frequent typhoons and severe wind intermittency) may increase the carbon footprint of offshore wind energy. But typhoons have never been considered in carbon accounting before, which may affect the design decisions of stakeholders and research priority setting for academicians. (i) To determine the effect of typhoons on carbon footprint, a life cycle assessment was performed on a typical offshore wind farm using real data. The results demonstrate that typhoons can be the largest contributor to carbon footprint, and the maximum wind speed of typhoons is the most critical parameter to carbon footprint. (ii) To quantify the carbon emissions caused by typhoons, simplified models estimating carbon emission intensity under different maximum wind speeds of typhoons are established, using Monte Carlo method based on 51 historical typhoons. The models imply that wind turbines with Permanent Magnet Synchronous Generator (PMSG) are highly recommended in typhoon-prone area, because their carbon footprint is smaller than those with Doubly-Fed Induction Generator (DFIG). (iii) To set carbon benchmarks for typhoons, statistic analysis was conducted based on the simulated samples generated by Monte Carlo method. The carbon benchmarks of typhoons show that gearbox has the highest carbon emission intensity (mean=4.35g/kW, 95th percentile=7.00g/kW) among all components, resulting DFIG with gearbox not suitable in typhoon-areas. The site selection of offshore wind farms in Southeast China should avoid areas where the maximum wind speed of typhoons exceeds 44.5 m/s. This study emphasizes the importance of typhoons in carbon footprint accounting for offshore wind farms in Southeast China. More significantly, the proposed simplified models and carbon benchmarks of typhoons can be applied to feasibility studies in early design stage for engineers and stakeholders.

Effect of typhoons on spatiotemporal patterns of multi-group persistent organic pollutants in sediment of Chinese southeastern coastal estuaries

Estuaries are susceptible to both anthropogenic disturbances and global climate changes. Impacts may be discriminated by pollution patterns of widely quantified persistent organic pollutants (POPs), though data are scarce for extreme climate events. This study quantified four groups of POPs, i.e., polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs), and hexachlorocyclohexanes (HCHs), in sediments from seven Chinese coastal estuaries across a gradient of socioeconomic development in their watersheds with comparisons among the pre-typhoon, typhoon, and post-typhoon periods during 2016–2019. The maximal average concentrations, up to 1561 μg PAHs kg−1, 235 μg DDTs kg−1, and 38.9 μg HCHs kg−1, were quantified in the Jiulong River estuary and 7.61 μg PCBs kg−1 in the Jiao River estuary. Anthropogenic activities contributed to the distinctive spatial distributions of four groups of POPs in estuaries with non-agricultural gross domestic product (NAGDP) per capita significantly relating to sedimentary concentrations of PAHs and PCBs and agricultural gross domestic product (AGDP) per capita relating to DDTs and HCHs. Seasonality and typhoons led to less temporal variations in sedimentary POPs concentrations, whose spatial heterogeneity was remarkably reduced in the post-typhoon period rather than in the pre-typhoon and typhoon periods. The results of this study suggested that fingerprinting legacy POPs in spatial and temporal distributions contributed to identifying the effects of anthropogenic disturbances and climate changes on estuarine sediment quality.

Marine ecological effect of typhoon influenced by the frequency-phases of ENSO and anthropogenic activity: the East China Sea example

In coastal regions, typhoons are one of the most frequent natural disasters, and instrumental data indicate that they can greatly boost marine primary productivity. Typhoons' long-term ecological repercussions, however, are still little understood. To investigate the ecological effects of typhoons since the mid-Holocene, we focused on the sediment cores in the East China Sea, with key parameters of organic CN and Bio-Si to reveal the paleo-productivity variation. Over a millennium, the occurrence of El Niño-Southern Oscillation (ENSO) has had a substantial impact on primary productivity in the southern East China Sea. The primary productivity in the southern East China Sea was risen by humid climate conditions in ∼3.0–2.0 ka and frequent typhoons in 1.5–0 ka. With a millennial period, ENSO frequency has been significantly influencing primary productivity in the southern East China Sea since the mid-Holocene. During 1.5–0 ka, frequent ENSO events have led to more frequent typhoons, which caused terrestrial materials input and water vertically mix in the southern East China Sea, ultimately increasing primary productivity. Particularly on a centennial time scale, ENSO phases determined how much primary productivity was increased, and this magnitude was bigger during the La Niña-like periods than it was during the El Niño-like periods since La Niña is when typhoons occur more frequently. During the Little Ice Age, the cold climate hindered the reproduction of phytoplankton, but increased human activities in Taiwan resulted in more soil erosion and the supply of terrestrial-derived nutrients into the sea, then amplified the typhoon-induced increase in primary productivity. As a result, this stage showed the highest primary productivity since the mid-Holocene. This study reveals that frequent typhoons promote marine primary productivity on centennial-millennial timescales and emphasizes that human activities amplify the ecological effect of typhoons in recent centuries.

Serviceability Evaluation of High-Rise Buildings Exposed to Typhoon Proximity Effects Using ISO10137 and ISO6897

This study evaluates the vibration data of high-rise buildings during a typhoon by measuring the vibration data and using international serviceability standards. In order to do this, the horizontal vibration serviceability evaluation standards of each country were surveyed, but the standards that could be applied were limited to ISO10137 and ISO 6897. Despite the trend that the discomfort of residents increases as the number of high-rise buildings increases, the current standards are for high-frequency vibrations, such as machine vibrations or vertical floor vibrations, so there is an urgent need for research on new evaluation methods for low-frequency horizontal vibrations. As a result of analyzing the effects of typhoons on buildings, the study’s target building had low natural frequencies of less than 1 Hz, and the highest acceleration was observed to be amplified up to about 160 times due to the effects of Typhoon Danas and Chaba, but there was no change in the natural frequency. When this result was applied to the horizontal vibration serviceability evaluation, it was found that the likelihood of residents perceiving vibration was low during constant vibration, but during strong winds, the size of the top-floor horizontal vibration exceeded the average level of vibration perception proposed by ISO standards, so most residents of high-rise buildings would be likely to perceive the vibration as uncomfortable.

Measuring the effects of typhoon trajectories on dengue outbreaks in tropical regions of Taiwan: 1998-2019.

Dengue fever is a rapidly spreading mosquito-borne contagion. However, the effects of extreme rainfall events on dengue occurrences have not been widely evaluated. With their immense precipitation and high winds, typhoons may have distinct effects on dengue occurrence from those during other heavy rain events. Frequented by typhoons and situated in the tropical climate zone, southern Taiwan is an appropriate study area due to its isolated geographic environment. Each subject to distinct orographic effects on typhoon structure and typhoon-induced precipitation, 9 typhoon trajectories around Taiwan have not been observed until now. This study analyzes typhoon-induced precipitation and examines historical typhoon events by trajectory to determine the effects of typhoons on dengue occurrences in different urban contexts of Tainan and Kaohsiung in high-epidemic southern Taiwan. We employed data from 1998 to 2019 and developed logistic regression models for modeling dengue occurrence while taking 28-day lag effects into account. We considered factors including typhoon trajectory, occurrence, and typhoon-induced precipitation to dengue occurrences. Our results indicate that typhoon trajectories are a significant risk factor for dengue occurrence. Typhoons affect dengue occurrence differently by trajectory. One out of four northbound (along the Taiwan Strait) and four out of five westbound (across Taiwan) typhoons were found to be positively correlated with dengue occurrences in southern Taiwan. We observe that typhoon-induced precipitation is not associated with dengue occurrence in southern Taiwan, which suggests that wind destruction during typhoon events may serve as the primary cause for their positive effects by leaving debris suitable for mosquito habitats. Our findings provide insights into the impact of typhoons by trajectory on dengue occurrence, which can improve the accuracy of future dengue forecasts in neighboring regions with similar climatic contexts.

Remote dynamic and thermodynamic effects of typhoons on Meiyu–Baiu precipitation in Japan assessed with bogus typhoon experiments

To advance comprehensive knowledge of typhoon-induced remote precipitation and anomalous atmospheric circulations during the early summer rainy season (Meiyu-Baiu), we performed numerical simulations in which different bogus typhoons are imbedded in the July climatological mean field as ideal initial and lateral boundary conditions using a regional atmospheric model, and we compared experiments with and without the bogus typhoon. The dominance of an anomalous local high (ALH) remotely induced by a typhoon leads to a poleward shift of the primary Meiyu–Baiu frontal zone in the form of the enhancement of the North Pacific subtropical high (NPSH). Typhoon-induced negative potential vorticity advection plays a dominant role in forming the ALH around Japan. Despite the shift of the frontal zone, heavy precipitation in excess of 100 mm per day occurs along the Pacific coast of western Japan, which is triggered by two primary moisture inflows. One is the low-level moisture inflow along the moisture conveyor belt (MCB), which is an appreciable low-level moisture flux zone stretching from the Indian Ocean to a typhoon over the western North Pacific, due to the intensified horizontal pressure gradient between the typhoon and the NPSH. The MCB is more robust in the experiment in which the typhoon is close to the South China Sea where the monsoon westerlies prevail. The parcels along the MCB bring moisture into western Japan even though moisture losses due to condensation occur on the way, to some degree. The other is the moisture inflow through the atmospheric boundary layer along the southwestern periphery of the NPSH. The parcels along the NPSH periphery easily receive moisture from the underlying ocean as they approach western Japan. Both inflows are enhanced by the ALH formation over Japan. The combined effect of the typhoon and its induced ALH is responsible for the prominence of the two major moisture inflows into western Japan, leading to local heavy precipitation in that region.