Effects Of Typhoon Research Articles

Effects of typhoon and upwelling on Chlorophyll-a distribution in the northeastern coast of Hainan during Summer.

Typhoons or upwelling are thought to promote higher phytoplankton chlorophyll-a (Chl-a) concentration in many previous studies. However, the combined effects of typhoons and upwelling have been less studied in the South China Sea. Based on satellite remote sensing data, we investigated potential contributions of temperature-characterizing upwelling and typhoon events to Chl-a changes in the Hainan northeast area. Results showed that the Chl-a concentration was 0.80 mg m-3 at the coastal upwelling index (CUI) of 1.7°C in the summer of 2020 when there were no typhoons crossing the area. The CUI (1.01°C) of typhoon-influenced period in 2019 was 0.21°C higher than that of typhoon-free period in 2019. And the Chl-a also increased from 0.70 mg m-3 to 0.99 mg m-3. In comparison, during the typhoon-free period, with the higher CUI, there was the higher concentration of Chl-a. In addition, the typhoon affected Chl-a concentration is significantly higher than that in the other two typhoon-free periods of 2019 and 2020. Though the typhoon has a limited effect on the upwelling intensity, the Chl-a concentration is much higher than when the upwelling acts alone. This is due to the combined effect of typhoon (vertical mixing and runoff) and upwelling. The above results indicate that upwelling dominated the changes in Chl-a concentration in the Hainan northeast upwelling area during the typhoon-free period. In contrast, strong vertical mixing and runoff dominated the changes of Chl-a concentration during the typhoon-influenced period in the above area.

Effects of Typhoon In‐Fa (2021) and the Western Pacific Subtropical High on an Extreme Heavy Rainfall Event in Central China

AbstractAn extreme heavy rainfall event in Henan Province (HnHRE) of central China in July 2021, which is jointly affected by the western Pacific subtropical high (WPSH) and Typhoon In‐Fa (2021), is comprehensively studied through five experiments conducted using the Weather Research and Forecasting Model (WRF). The patterns of the WPSH, In‐Fa, and precipitation are well reproduced in the control experiment. The magnitude of potential vorticity (PV) anomaly associated with the WPSH (In‐Fa) is increased and decreased by 50% in the initial condition based on the piecewise PV inversion method, namely, SH150 and SH050 (TC150 and TC050), respectively. The analysis shows that the 54‐hr rainfall accumulations in TC150 and TC050 are reduced by 39.5% and 31.8%, respectively, more than 28.8% in SH150 and 20.1% in SH050, indicating that Typhoon In‐Fa plays a more critical role in the rainfall amplification than the WPSH. This result also confirms that the HnHRE occurs within the quite favorable configuration of WPSH and In‐Fa circulations. The WPSH and In‐Fa majorly control the meridional and zonal moisture transports, respectively. The diagnosis of moist ageostrophic turns out that diabatic heating is closely related to the vertical motion during the HnHRE. Besides, the heavy rainfall region is also closely attributed to the distributions of equivalent potential temperature and divergence.

Downdrift Port Siltation Adjacent to a River Mouth: Effects of Mesotidal Conditions and Typhoon

The Zhuoshui River has one of the highest sediment yields in the world. The riverine sediment may have been transported away from the river mouth by strong tidal currents and deposited in a navigational channel and a harbor basin south of the Zhuoshui River. This study describes the dispersal of riverine sediments in mesotidal conditions, including transport processes of sediments via river plumes, initial deposition, resuspension, and long-term net accumulation. Our results revealed that the distribution of suspended sediment concentration (SSC) and the transport process of the river plume was markedly modulated by tidal currents in a north–south direction. Under high-discharge conditions, energetic winds and ocean currents interrupted the offshore propagation of the sediment-laden river plume with a high SSC to the ocean. The plume, induced by typhoon floods, was either propagated northward due to the Coriolis effect or was deposited near the river mouth. The sediments deposited within the inner shelf were resuspended by intensive tidal currents and transported through southward residual circulations to the navigation channel south of the river mouth.

Characteristics of wave energy resources on coastal waters of northeast Taiwan

Hourly measurements of wave data for 10–14 years from four field stations were analyzed to evaluate wave energy resource characteristics in medium wave power potential coastal waters of northeast Taiwan. Spectral parameters, resource index, and constitutive energy periods were discussed. Time series of water surface displacement in each hour for three consecutive years at two stations were first adopted to obtain period transferring coefficient Cep of 0.86–0.87 for JONSWAP's peak enhancement factor γ of 1.5–1.6. The derived average wave energy scatter maps characterized indices of monthly and seasonal variations and highlighted the effects of typhoon and higher potentials by monsoons with increasing waves from NE. Comparisons with previous numerical simulations on sites offshore northeastern coasts pointed out slightly higher energy potentials at present field stations suggesting field measurements being vital for resource assessment. From energy scatter maps of two representative geographical zones, 15 and 16 top-ranked bin conditions were selected to display concentrations on constitutive energy periods from 6 s to 10 s. Similar selections were applied to foreign energy resources in Pacific and Atlantic coastal waters to show major energy potentials at higher latitudes concentrated on constitutive period ranges by 2 s longer.

Disentangle the effects of environment and disturbance on landscape dynamics using LANDIS forest landscape model

Forest landscapes pattern and development are affected by environment and disturbance. Disentangling their effects is important to understanding current landscape and predicting future changes. Such studies are limited by short-term observation and sparse disturbance-history data. Spatially-explicit forest landscape modeling represents a solution to these limitations. Here, we reconstructed the 300-year-time-series (1710–2010) of post-volcanic-eruption forest landscapes experiencing periodic-typhoons in Changbai Mountain, China, using LANDIS forest landscape model. We used a factorial simulation design to quantify the main and interactive effects of environment and typhoon on forest landscape recovery. Results showed environment had dominant effects (>80%) on early recovery (1710–1760), suggesting early forest development follows deterministic community-assembly processes governed by environment. However, as forest matured, disturbance became dominant (>50%) at later-recovery stages (1860–2010). This study showed that historical landscape reconstruction reveals the full spectrum of interplays of environment, disturbance, and succession in forest ecosystems, which may not be captured by short-term studies.

Effects of Typhoon on Saltwater Intrusion in a High Discharge Estuary

AbstractSaltwater intrusion in the Changjiang Estuary occurs in winter and dry season, which may affect drinking water supply in Shanghai. An atypical saltwater intrusion event, observed under high river discharge (>20,000 m3/s) in October 2018, coincided with the passage of super typhoon Kong‐rey. The response of the estuarine salt field is reproduced here with a numerical model for analysis with a Eulerian framework. Model results show that saltwater intrusion was mainly due to the landward advection of salt (∼260 t/s), which was driven by the storm surge (∼0.4 m) and landward Ekman transport under typhoon winds. The sheared salt flux (∼145 t/s) significantly contributes to the total landward flux, especially when the surge recedes after the typhoon has passed. Northwesterly winds increased vertical shear and stratification during the event. The maximum saltwater intrusion occurred about a day after the typhoon passage, and the salinity at the freshwater reservoir intake exceeds the local drinking standard of 0.45 psu. A numerical experiment shows that if Kong‐rey had passed during spring tide, the saltwater intrusion would have been weaker due to a stronger northward transport near the coast and a landward transport in the southern channels.

Responses of Hydrodynamics and Saline Water Intrusion to Typhoon Fongwong in the North Branch of the Yangtze River Estuary

The typhoon impact on an estuarine environment is complex and systematic. A three-dimensional hydrodynamic and salinity transport model with a high-resolution, unstructured mesh and a spatially varying bottom roughness, is applied to investigate the effects of a historical typhoon, Fongwong, which affected Shanghai, on the hydrodynamics and saline water intrusion in the North Branch (NB) of the Yangtze River Estuary (YRE). The model is well validated through observation data of the tidal level, current velocity and direction, and salinity. The numerical results of this typhoon event show that: (1) the tidal level and its range increase toward the upstream part of the NB due to the combined effects of the funnel-shaped plane geometry of the NB and the typhoon; (2) the current velocity and the flow spilt ratio of the NB varies with the tides, with a maximum increase by 0.13 m/s and 26.61% during the flood tide and a maximum decrease by 0.12 m/s and 83.33% during the ebb tide, i.e., the typhoon enhances the flood current and weakens the ebb current; (3) the salinity value increases in the NB to a maximum of 1.40 psu and water is well-mixed in the vertical direction in the typhoon’s stable and falling period. The salinity distribution gradually recovered to the normal salt wedge pattern in 3 days following the typhoon. Although this study is based on a site-specific model, the findings will provide valuable insights into saline water intrusion under typhoon events, and thus assist in implementing more efficient estuarine management strategies for drinking water safety.

城市园林不同生活型植物叶片碳、氮、磷生态化学计量特征及其对台风的响应

植物碳（C）、氮（N）、磷（P）含量及其化学计量比对于维持植物的正常生长发育具有重要意义。台风可能通过多种途径影响我国沿海城市园林植物的生长发育，并改变园林植物C、N、P含量及其生态化学计量特征。然而，相关研究鲜有报道，亟待深入。因此，在2020年8月黑格比台风登陆我国浙江省前后，我们对比研究了台风来临前、台风影响期间以及台风过境一周后，台州市主城区常见的乔、灌、草园林植物叶片C、N、P含量及其生态化学计量比变化特征。结果表明：（1）乔、灌、草园林植物叶片的C/N分别为27.3±0.6、42.9±1.4、25.4±2.2，C/P分别为208.8±9.3、194.1±9.6、88.5±5.7，N/P分别为7.7±0.4、4.9±0.2、4.2±0.5，表明研究区域城市园林植物受到N的限制。（2）不同生活型的园林植物叶片C、N、P含量受台风的影响存在不同程度的差异。C与N含量受台风的影响程度均表现为草本>灌木>乔木，P含量受台风的影响程度表现为草本>乔木>灌木。（3）不同生活型的园林植物叶片C、N、P生态化学计量比对台风的响应存在差异。C/N受台风的影响程度表现为草本>灌木>乔木，C/P受台风的影响程度表现为草本>乔木>灌木，而N/P受台风的影响程度表现为乔木>草本>灌木。台风影响一周后，乔、灌、草园林植物叶片C、N、P含量及生态化学计量比能够自我调节进行恢复。可见，台风会对不同生活型的园林植物叶片基础元素含量及生态化学计量比产生不同程度的影响，而园林植物可通过自身内稳态调节机制使台风的影响减小到最低。;The concentrations of carbon (C), nitrogen (N) and phosphorus (P), and their ecological stoichiometric ratios in plant tissues play an important role in maintaining the growth and development of plants. Although the typhoons could affect the growth and development of garden plants in coastal cities of China in many ways, the effects of typhoon on the ecological stoichiometric characteristics of carbon, nitrogen and phosphorus in urban garden plants have not been demonstrated. Therefore, the concentrations of C, N and P in leaves of common garden trees, shrubs and herbs were measured in Taizhou City, a coastal city in Zhejiang Province before one day, after one day and one week of Typhoon Hagupit in August 2020, respectively. Then, the short-term effects of typhoon Hagupit on the concentrations and stoichiometric ratios of C, N and P in these garden plant leaves were evaluated. The C/N ratio of the investigated garden trees, shrubs and herbs is 27.3±0.6, 42.9±1.4 and 25.4±2.2, respectively; the C/P ratio is 208.8±9.3, 194.1±9.6, 88.5±5.7, respectively; and the N/P ratio is 7.7±0.4, 4.9±0.2, 4.2±0.5, respectively, implying that the investigated urban garden plants are limited by N. The concentrations of C, N and P in garden plant leaves of different life forms were affected by the typhoon to varying degrees, but the concentrations of the measured bioelements gradually recovered to the original level after one week of typhoon impact. Both C and N concentrations in plant leaves were affected by typhoon followed as herb > shrub > tree, while the concentration of P in plant leaves was affected by typhoon followed as herb > tree > shrub. The differential responses of C, N and P stoichiometric ratios in garden plants to the typhoon Hagupit were observed among different plant life forms. The ratio of C to N in plant leaves were affected by the typhoon followed as herb > shrub > tree, the ratios of C to P in plant leaves were affected by the typhoon followed as herb > tree > shrub, and the ratio of N to P in plant leaves were affected by the typhoon followed as tree > herb > shrub, respectively. After one week of the typhoon Hagupit, the concentrations and stoichiometric ratios of C, N and P in garden plants gradually recovered to the pre-typhoon level. In conclusion, the typhoon can have to a certain extent effects on C/N/P stoichiometry of garden plants of different life forms, and garden plants can minimize the impact of typhoon by regulating their homeostasis.

Surface wave field under binary typhoons Sarika and Haima (2016) in South China Sea

The effects of the binary typhoon on the surface wave field in the South China Sea (SCS) were investigated using the third-generation wave model WaveWatch Ⅲ (WWⅢ). The surface wave field during the binary typhoons Sarika and Haima (2016) was reproduced with blended winds and two nested domains, and the simulation results obtained are in good agreement with the satellite altimeter data. To investigate different wave characteristics under binary and individual typhoons, a numerical experiment was designed with the multi-annual mean winds replacing one cyclone of the blended binary typhoons, and its results were compared with the simulation results of realistic binary typhoons. The comparison suggests that the surface waves induced by the binary typhoon not only have higher intensity, but also exhibit more complex behaviors. Binary typhoons cause an increase in the significant wave height (Hs) inside the maximum wind radius of the latter typhoon (Haima). Factors affecting the enhanced Hs on the surface wave field include typhoon intensity, maximum wind radius, and typhoon translation speeds. The interactions between waves generated by Haima and Sarika enhance extreme waves by 4%–5%. The response of wave characteristics of Sarika and Haima to the monsoon winds is different. For wave spectra, bi-modal features are widespread on the surface wave field between the interval of the two typhoons, even if the separation distance between them is greater than 1700 km.

Short- and Long-term Effects of Typhoon 0418 on Macrobenthic Community in Tidal Flats on the Coast of Iwakuni in Hiroshima Bay

Short- and Long-term Effects of Typhoon 0418 on Macrobenthic Community in Tidal Flats on the Coast of Iwakuni in Hiroshima Bay

Recolonization of mollusc assemblages in mangrove plantations damaged by Typhoon Chan-hom in the Philippines

We investigated the effects of a catastrophic typhoon on mollusc assemblages of damaged mangrove plantations of different ages. Molluscs were sampled from infaunal, epifaunal and arboreal assemblages of mangrove stands in Lingayen Gulf, northwest Philippines, and compared with assemblages of un-impacted areas. Prior to the occurrence of the typhoon, there were clear shifts in the species diversity (H’) and composition of mollusc assemblages with stand age of mangrove forests. This was observed in species composition through the succession in dominance from pioneer to seral or putative climax species, and assemblage type (as arboreal, epifaunal and infaunal). However, severe damage to vegetation structure and sediment properties (associated with a reduction in tree density and canopy cover resulting in increased temperatures and exposure) following the typhoon resulted in an alteration of trajectory patterns in the damaged stands. There were shifts in species composition and dominant species from having mature mangrove-associated species (pre-typhoon) to an abrupt return in dominance of pioneer species (post-typhoon). The damage was more evident in older stands than in intermediate-aged stands. Furthermore, the reduced presence of molluscs (and also probably their activities, i.e. burrowing) may have contributed to the delayed recovery of mangroves. The prospects for recovery of the system to pre-typhoon levels are therefore uncertain where the re-establishment of seral or edaphic mollusc assemblages appears to be related to the recovery of vegetation and sediment conditions.

Monitoring wind effects of a landfall typhoon on a 600 m high skyscraper

This article presents the observations of the atmospheric boundary layer (ABL) and wind effects on a 600 m high skyscraper during a landfall typhoon. Wind structure and characteristics throughout the entire ABL are presented and discussed based on records from a Doppler radar wind profiler and near-ground measurements at several meteorological stations. Wind speed profiles with the feature of low-level jets and radial-distance and exposure dependences of gradient height are stressed. Afterwards, wind-induced pressures on building surfaces of the skyscraper are investigated with highlights on non-Gaussian probability distributions of negative pressures and vortex shedding occurred alternately at two sides of the building. The structural responses measured by both accelerometers and strain gauges are analyzed subsequently. Modal parameters of the skyscraper and their dependence on response amplitude are presented and discussed. This study aims to provide useful information for the wind-resistant design of skyscrapers in tropic cyclone-prone regions.

Logic tree approach for probabilistic typhoon wind hazard assessment

Abstract Global warming and climate change are increasing the intensity of typhoons and hurricanes and thus increasing the risk effects of typhoon and hurricane hazards on nuclear power plants (NPPs). To reflect these changes, a new NPP should be designed to endure design-basis hurricane wind speeds corresponding to an exceedance frequency of 10−7/yr. However, the short typhoon and hurricane observation records and uncertainties included in the inputs for an estimation cause significant uncertainty in the estimated wind speeds for return periods of longer than 100,000 years. A logic-tree framework is introduced to handle the epistemic uncertainty when estimating wind speeds. Three key parameters of a typhoon wind field model, i.e., the central pressure difference, pressure profile parameter, and radius to maximum wind, are used for constructing logic tree branches. The wind speeds of the simulated typhoons and the probable maximum wind speeds are estimated using Monte Carlo simulations, and wind hazard curves are derived as a function of the annual exceedance probability or return period. A logic tree decreases the epistemic uncertainty included in the wind intensity models and provides reasonably acceptable wind speeds.

One-Dimensional (1D) River Analysis of a River Basin in Southern Luzon Island in the Philippines Using Lidar Digital Elevation Model

Flooding is a perennial problem in the Philippines during the monsoon season intensified by the effects of typhoon. On average, there are 20 typhoons that enter the Philippine Area of Responsibility (PAR), and many of these make landfall causing catastrophic aftermath. Extreme rainfall events could lead to flooding in the downstream floodplain and landslide in mountainous terrains. In this study, which is for the case of Calumpang River that drains to the populated and developing region of Batangas City, the focus is on flooding in the floodplain areas. The river was modelled using LiDAR digital elevation model (DEM) that has an accuracy of 20cm in the vertical and 50cm in the horizontal. The result of this is river hydraulic model that can be used to accurately generate flood inundation simulations and flood hazard maps.

Impacts of increasing typhoons on the structure and function of a subtropical forest: reflections of a changing climate

Due to their destructive and sporadic nature, it is often difficult to evaluate and predict the effects of typhoon on forest ecosystem patterns and processes. We used a 21-yr record of litterfall rates to explore the influence of typhoon frequency and intensity, along with other meteorological variables, on ecosystem dynamics in a subtropical rainforest. Over the past half century there has been an increasing frequency of strong typhoons (category 3; >49.6 m s−1; increase of 1.5 typhoons/decade) impacting the Fushan Experimental Forest, Taiwan. At Fushan strong typhoons drive total litterfall mass with an average of 1100 kg ha−1 litterfall typhoon−1. While mean typhoon season litterfall has been observed to vary by an order of magnitude, mean litterfall rates associated with annual leaf senescence vary by <20%. In response to increasing typhoon frequency, total annual litter mass increased gradually over the 21-year record following three major typhoons in 1994. Monthly maximum wind speed was predictive of monthly litterfall, yet the influence of precipitation and temperature was only evident in non-typhoon affected months. The response of this subtropical forest to strong typhoons suggests that increasing typhoon frequency has already shifted ecosystem structure and function (declining carbon sequestration and forest stature).

APPLYING UAV AND PHOTOGRAMMETRY TO MONITOR THE MORPHOLOGICAL CHANGES ALONG THE BEACH IN PENGHU ISLANDS

Penghu islands, in the southern Taiwan Strait, is a remnant of a middle-late Miocene basaltic shield volcano. We present a procedure to use UAV (Unmanned Aerial Vehicles) to perform photogrammetry survey and monitoring analysis in beach evolution scenarios. The aim of this study is to understand spatial-temporal change along the sandy beach in Penghu islands, especially as for the effects of typhoon and coastal structures. According to the study result, this example of application is provided to show the results and the potential of this methodology in real beach changes. In addition, we found the typhoon and coastal structures play important roles to shape the beach morphology and its evolution. The result of beach monitoring reveals that the reduction and change of sand volume in Shanshui beach resulted from the placement of detached breakwater complexes. This coastal structure likely resulted in the development of tombolo and therefor make the beach unstable and subject to conduct rip current and more erosion.

APPLYING UAV AND PHOTOGRAMMETRY TO MONITOR THE MORPHOLOGICAL CHANGES ALONG THE BEACH IN PENGHU ISLANDS

Abstract. Penghu islands, in the southern Taiwan Strait, is a remnant of a middle-late Miocene basaltic shield volcano. We present a procedure to use UAV (Unmanned Aerial Vehicles) to perform photogrammetry survey and monitoring analysis in beach evolution scenarios. The aim of this study is to understand spatial-temporal change along the sandy beach in Penghu islands, especially as for the effects of typhoon and coastal structures. According to the study result, this example of application is provided to show the results and the potential of this methodology in real beach changes. In addition, we found the typhoon and coastal structures play important roles to shape the beach morphology and its evolution. The result of beach monitoring reveals that the reduction and change of sand volume in Shanshui beach resulted from the placement of detached breakwater complexes. This coastal structure likely resulted in the development of tombolo and therefor make the beach unstable and subject to conduct rip current and more erosion.

Study on a Numerical Navigation System in the East China Sea

High winds, ocean current as well as wind-induced ocean waves can affect ship safety and navigation cost. To avoid such rough ocean states and make use of beneficial ocean current, an exact ship position considering about the weather and ocean information is of great importance. In our study, a powerful typhoon in the Kuroshio Current area of the East China Sea was studied to construct the Numerical Navigation System. Information of ocean winds, wind-induced ocean waves as well as the strong western boundary Kuroshio Current is firstly generated by modern weather and ocean models as a combination and then provided to a ship maneuvering model to construct a numerical ship navigation system. Effects of typhoon, wind-induced ocean waves as well as ocean currents on ship navigation could be found quantitatively by utilizing this method.

Effects of Orography on the Tail-End Effects of Typhoon Ketsana

The study of tail-end effects of typhoon on orography is new to Malaysia. The current study used FY-2D satellite data to investigate the variation of selected parameters of the Typhoon Ketsana system. In situ data, obtained via the radiosonde technique, were used to verify the atmospheric conditions, whereas the Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model was applied to determine the structure of the mountains in East Malaysia (EM). This study aimed to identify typhoon-terrain effects, in terms of wind, cloud, and rain of the tail-end effects of typhoon in a regional environment. The tail-end effects of Typhoon Ketsana were altered by the orography in EM such that a slow movement with higher rate of rainfall was distributed along the mountainous western region, and cloud classification distribution patterns were different before, during, and after the tail-end effects of the typhoon. The wind intensity increased with altitude and affected the larger atmosphere region over EM. Additionally, the location of the Sabah region puts it at a higher risk to the impact of the tail-end effect of typhoons compared with the Sarawak region due to its distance from the typhoon. This study concluded that the impacts of the tail-end effects of a typhoon can also be varied and enhanced by the orography.

The spatial and temporal characteristics of the wave energy resources around Taiwan

This study focused on the assessment of wave energy resources around the Taiwan sea area. The forecasted wave data of TaiCOMS, offered by Harbor and Marine Technology Center of Taiwan, records wave buoys deployed by the Central Weather Bureau of Taiwan, and information on typhoons were used to analyze the temporal and spatial characteristics of wave power density in Taiwan's coastal area. In addition, the effects of monsoon and typhoon that contributed to the wave energy resource were investigated, and the average annual wave power around Taiwan was also estimated. The northeastern coastal area is the potential area for wave energy usage in Taiwan. The peak density of wave power occurs in autumn and winter for most of Taiwan's sea area, except for the southwestern coast, in which peak seasons occur in spring and summer. These results imply that the wave power in Taiwan's sea area is dominated by monsoons. However, because a typhoon usually generates substantial power, the annual wave energy may be affected by the quantity, path, and scale of a typhoon that hits Taiwan. In particular, the effects of typhoons on to the annual wave energy are crucial for the southwestern coastal area. Finally, for resources assessment, the average annual wave energy of coastal area surrounding Taiwan Island was estimated to an amount of approximately 16.9 TWh per year.