Super Typhoon Research Articles

Microphysical processes of super typhoon Lekima (2019) and their impacts on polarimetric radar remote sensing of precipitation

Abstract. The complex precipitation microphysics associated with super typhoon Lekima (2019) and its potential impacts on the consistency of multi-source datasets and radar quantitative precipitation estimation were disentangled using a suite of in situ and remote sensing observations around the waterlogged area in the groove windward slope (GWS) of Yandang Mountain (YDM) and Kuocang Mountain, China. The main findings include the following: (i) the quality control processing for radar and disdrometers, which collect raindrop size distribution (DSD) data, effectively enhances the self-consistency between radar measurements, such as radar reflectivity (ZH), differential reflectivity (ZDR), and the specific differential phase (KDP), as well as the consistency between radar, disdrometers, and gauges. (ii) The microphysical processes, in which breakup overwhelms coalescence in the coalescence–breakup balance of precipitation particles, noticeably make radar measurements prone to be breakup-dominated in radar volume gates, which accounts for the phenomenon where the high number concentration rather than the large size of drops contributes more to a given attenuation-corrected ZH (ZHC) and the significant deviation of attenuation-corrected ZDR (ZDRC) from its expected values (Z^DR) estimated by DSD-simulated ZDR–ZH relationships. (iii) The twin-parameter radar rainfall estimates based on measured ZH (ZHM) and ZDR (ZDRM), and their corrected counterparts ZHC and ZDRC, i.e., R(ZHM, ZDRM) and R(ZHC, ZDRC), both tend to overestimate rainfall around the GWS of YDM, mainly ascribed to the unique microphysical process in which the breakup-dominated small-sized drops above transition to the coalescence-dominated large-sized drops falling near the surface. (iv) The improved performance of R(ZHC, Z^DR) is attributed to the utilization of Z^DR, which equals physically converting breakup-dominated measurements in radar volume gates to their coalescence-dominated counterparts, and this also benefits from the better self-consistency between ZHC, Z^DR, and KDP, as well as their consistency with the surface counterparts.

Classification modeling of intention to donate for victims of Typhoon Odette using deep learning neural network

The need for stability in the economy for world development has been a challenge due to the COVID-19 pandemic. In addition, the increase of natural disasters and their aftermath have been increasing causing damages to infrastructure, the economy, livelihood, and lives in general. This study aimed to determine factors affecting the intention to donate for victims of Typhoon Odette, a recent super typhoon that hit the Philippines leading to affect 38 out of 81 provinces of the most natural disaster-prone countries. Determining the most significant factor affecting the intention to donate may help in increasing the engagement of donations among other people to help establish a more stable economy to heighten world development. With the use of deep learning neural network, a 97.12% accuracy was obtained for the classification model. It could be deduced that when donors understand and perceive both severity and vulnerability to be massive and highly damaging, then a more positive intention to donate to victims of typhoons will be observed. In addition, the influence of other people, the holiday season when the typhoon happened, and the media as a platform have greatly contributed to heightening the intention to donate and control over the donor's behavior. The findings of this study could be applied and utilized by government agencies and donation platforms to help engage and promote communication among donors. Moreover, the framework and methodology considered in this study may be extended to evaluate intention, natural disasters, and behavioral studies worldwide.

Impact Analysis of Super Typhoon 2114 ‘Chanthu’ on the Air Quality of Coastal Cities in Southeast China Based on Multi-Source Measurements

The northward typhoon configuration along the southeast coast of China (TCN-SEC) is one of the key circulation patterns influencing the coastal cities in southeast China (CCSE). Here, we analyzed the air quality in CCSE during the high-incidence typhoon period from 2019 to 2021. Multi-source measurements were carried out to explore the impact of super typhoon 2114 ‘Chanthu’ on the air quality in CCSE. The results showed that the TCN-SEC and its surrounding weather situation had a favorable impact on the increase in pollutant concentration in CCSE, especially on the increase in O3 concentration. From 13 September to 17 September 2021, affected by the cyclonic shear in the south of super typhoon 2114 ‘Chanthu,’ the strong wind near the ground, stable relative humidity, strong precipitation, and the significantly reduced wind speed had a substantial effect on PM10, PM2.5, SO2, and NO2 concentrations. Calm and light air near the ground, weak precipitation, high daily maximum temperatures, and minimum relative humidity may provide favorable meteorological conditions for the accumulation of O3 precursors and photochemical reactions during the day, resulting in the daily peak values of O3 exceeding 160 μg/m3. The evolution of wind, relative humidity, and boundary layer height could play an important role in the variations in PM10 and PM2.5 concentrations by influencing pollutant accumulation or diffusion. It was suggested that the atmospheric structure of horizontal stability and vertical mixing below 1500 m could play a significant role in the accumulation and vertical distribution of ozone. The results highlight the important role of typhoons in the regional environment and provide a scientific basis for further application of multi-source observation data, as well as air pollution control.

Resiliency of seagrass beds in shallow waters of Tacloban City, Philippines after super Typhoon Yolanda

Resiliency of seagrass beds in shallow waters of Tacloban City, Philippines after super Typhoon Yolanda

Posttraumatic stress disorder symptoms among parents and adolescents following Typhoon Lekima: Examination of the mother-daughter sex matching effect.

This study aimed to examine the same-sex matching effect of posttraumatic stress disorder (PTSD) symptoms from parents to children and the mediating role of children' sense of security and catastrophization. Longitudinal data from 447 parent-child dyads were acquired using self-report scales. Parents (77.0% mothers; Mage = 40.15 years old) reported their PTSD symptoms 3 months after Super Typhoon Lekima, and children (55.9% girls; Mage = 13.40 years old) reported their PTSD symptoms, sense of security, and catastrophization 3 months and 15 months after the typhoon. Results showed that intrusion in mothers predicated intrusion, avoidance, and hyperarousal symptoms in daughters, while avoidance and hyperarousal in mothers predicted the same symptoms in daughters. This was not observed in any other parent-child dyads. Moreover, mothers' intrusion positively predicted daughters' PTSD symptoms via daughters' sense of security and then catastrophization, while mothers' hyperarousal showed the opposite prediction. These findings suggest that a same-sex matching effect occurs from mothers to daughters in terms of intrusion, avoidance, and hyperarousal symptoms of PTSD. Thus, clinical interventions that target daughters' PTSD symptoms should also consider mothers' intrusion and avoidance symptoms. Moreover, it may be possible to develop interventions to improve daughters' sense of security.

Monitoring and Evaluation Framework for Long Lasting Treated Nets (LLITN) Installation in Tacloban City

This paper addresses the need to come up with a monitoring and evaluation framework based on barangay visitations conducted by the Department of Health in conjunction with Oxford for Families (OXFAM) in the wake of super typhoon Haiyan that ravaged Tacloban City of Eastern Visayas, Philippines in 2013. The framework for monitoring and evaluation on LLIT installation together with barangay surveillance was drawn from collected narratives of the carpenters of LLITN, the community members, school pupils, administrators, and barangay leaders surrounding the different schools identified in the study. Installation of Long Lasting Insecticide Treated Nets (LLITN) alongside barangay surveillances were palliative interventions requiring constant monitoring and evaluation because dengue virus inflicts human beings and its carrier, mosquito, will continue to thrive in communities if not seriously dealt with. Qualitative data were gathered from direct interviews conducted through focus group discussions. Results indicated that LLITN installation in schools should be constantly monitored and evaluated because 1) school pupils can easily rip the fabric. 2) some areas in the classroom left open can render LLITN ineffective as mosquitoes can easily get in. 3) strength of the fabric can wane over time due to weather conditions 4) community and barangay surveillance on the presence of dengue-carrying mosquitoes indicate effectiveness of LLITN and overall dengue interventions. Finally, social mobilization on reducing dengue virus infection through social media campaign is relevant to engage community members to actively pursue a dengue-free environment.

Microphysical processes under different hourly rainfall intensities in super typhoon Rammasun

High-resolution numerical simulation data of super typhoon Rammasun simulated by the Weather Research and Forecasting (WRF) Model was used to study the cloud microphysical processes under different hourly rainfall intensities. The grid points in the gale circle were categorized into four types (0–5, 5–20, 20–50, and 50- mm) based on hourly rainfall. The precipitation and microphysical characteristics under different types were investigated by diagnostic and statistical methods. The results showed that on the eve of the first landfall, extremely hourly heavy precipitation (50- mm type) was significantly enhanced compared to other types. The vertical movement was significantly reduced to the middle and lower troposphere which was very conducive to the relative movement and interaction of hydrometeors with the enhancement of the collision processes. The rainfall in the 5–20 and 20–50 mm types both mostly accounted for about 40% of the total rainfall in the gale circle, while that of the 0–5 and 50- mm types were generally smaller than the former two. As the rainfall intensity increased, the absolute conversion rates of all major cloud microphysical processes had shown increasing trends, especially the non-uniformity of Cnd (the condensation of water vapor to cloud water), Pracw (the accretion of cloud water by rain) and Dgacw (the accretion of cloud water by graupel). The relative contribution of Pgmlt (the melting of graupel) increased slightly and then decreased significantly from the 20–50 mm type (36.28%) to the 50- mm type (25.06%), while that of Pracw had significantly increased especially from the 20–50 mm type (41.77%) to the 50- mm type (50.97%), which was related to the upward motion characteristics.

Evaluation and impact factors of Doppler wind lidar during Super Typhoon Lekima (2019)

Doppler wind lidar (DWL) has been widely employed in the wind energy industry. However, the evaluation of DWL winds under typhoon conditions is still rare. This study evaluated the accuracy of wind data measured by two types of DWLs (WindPrint S4000 and WindCube V2), and investigated the impact of three environmental factors (precipitation intensity, relative humidity and drift distance of sounding balloons) on the DWL-measured wind speed and direction. Data were collected from the joint observation at Baoshan, Zhoushan and Taizhou during the passage of Super Typhoon Lekima in 2019. The DWL observations were compared with measured data from balloon-borne radiosonde released at the same location. The results show that the optimal agreement was found with the 1-min average DWL-measured winds. The DWL data missing rate decreases with the increase of signal-to-noise ratio and height from the surface. The applicability of DWL is poor when the precipitation intensity is larger than 50 mm h−1. The DWL wind speed and wind direction biases significantly increase when the relative humidity exceeds 85% and 90%, respectively. Moreover, the measured wind data of the balloon-borne radiosonde are not reliable when the horizontal drift distance is larger than 2 km.

Investigation of wind characteristics of typhoon boundary layer through field experiments and CFD simulations

High-resolution observations of typhoon boundary layer above 100 m are rare as traditional wind towers are generally below 100 m, which limits the study of typhoon boundary layer and engineering applications such as wind-resistant design of tall buildings and wind turbines in typhoon-prone regions. In this study, boundary layer winds of super typhoon Lekima (2019) are observed, simulated and analyzed. Together with traditional wind tower, Doppler wind lidar is utilized for observations of typhoon boundary layer in order to obtain measured data above 100 m. Besides, Computational Fluid Dynamics (CFD) simulation based on Large Eddy Simulation (LES) method is conducted to further investigate the impact of complex terrain on the near-surface wind characteristics. The results show that the power law fits the mean wind speed profile well below 100 m. However, before and after the typhoon lands, a local reverse or low-level jet occurs in the mean wind speed profile at the height of 100–300 m, which cannot be depicted by the power law. Meanwhile, the turbulence intensity increases with height and experiences larger fluctuations. In addition, there is a significant negative correlation between the ground elevation and power exponents of the fitted mean wind speed profiles. This study provides useful information to better understand wind characteristics of the typhoon boundary layer.

Data for vertical distribution char acteristics of the super typhoon gust factor based on a 356-m high meteorological gradient tower

Data for vertical distribution char acteristics of the super typhoon gust factor based on a 356-m high meteorological gradient tower

Developing a Climate Change Risk Perception Model in the Philippines and Fiji: Posttraumatic Growth Plays Central Role

This two-study paper developed a climate change risk perception model that considers the role of posttraumatic growth (i.e., a reappraisal of life priorities and deeper appreciation of life), resource loss, posttraumatic stress, coping, and social support. In Study 1, participants were 332 persons in the Philippines who experienced Super Typhoon Haiyan. In Study 2, participants were 709 persons in Fiji who experienced Cyclone Winston. Climate change can increase the size and destructive potential of cyclones and typhoons as a result of warming ocean temperatures, which provides fuel for these storms. Participants completed measures assessing resource loss, posttraumatic stress, coping, social support, posttraumatic growth, and climate change risk perception. Structural equation modeling was used to develop a climate change risk perception model with data collected in the Philippines and to confirm the model with data collected in Fiji. The model showed that climate change risk perception was influenced by resource loss, posttraumatic stress, coping activation, and posttraumatic growth. The model developed in the Philippines was confirmed with data collected in Fiji. Posttraumatic growth played a central role in climate change risk perception. Public health educational efforts should focus on vividly showing how climate change threatens life priorities and that which gives life meaning and can result in loss, stress, and hardship. Disaster response organizations may also use this approach to promote preparedness for disaster threats.

Multi-scale characteristics of an extreme rain event in Shandong Province, produced by Typhoon Lekima (2019)

Super Typhoon Lekima (2019) is the fifth strongest typhoon to make landfall in mainland China since 1949. After its landfall, Typhoon Lekima moved northward along the coastline, resulting in an extreme rain event in Shandong Province that caused the highest precipitation in available meteorological records. A Weather Research and Forecasting (WRF) model simulation that properly produces the track and intensity of Typhoon Lekima and the spatio-temporal evolution of rainfall is used to analyze the multi-scale characteristics of the extreme rain event. The results show that different from the typhoon precipitation which occurred at low latitudes, the extreme rain event that occurred in mid-latitudes was influenced by the interactions of mid-latitude synoptic systems and typhoon circulation, especially with five mesoscale rainbands. The mid-latitude synoptic systems, mainly including the upper-tropospheric jet, the western North Pacific subtropical high, the mid-latitude trough, the low-level jets, and Typhoon Krosa (2019), allowed Typhoon Lekima to maintain its intensity after landfall and provided favorable kinematic, thermodynamic, and moisture conditions for the heavy rainfall in Shandong. Based on the evolution of the mesoscale rainbands, the extreme rain event can be divided into three stages. The first stage can be classified as distant rainfall, which was affected by two convective rainbands associated with boundary-layer processes. The second stage had the highest precipitation, featuring the formation of a frontal zone in Shandong, interacting with Typhoon Lekima. The third stage had weakened rainfall and was directly influenced by the spiral rainband of Typhoon Lekima.

Dynamic response evaluation of the Shanghai Tower in along- and across-wind directions during super typhoon Lekima

The dynamic responses of the Shanghai Tower (ST) under Typhoon Lekima in 2019 were evaluated in the along- and across-wind directions based on SHM data. Compared to most similar studies that focus on two main axes of the buildings, this study focused on such dynamic responses in the along- and across-wind directions; these processes were also widely discussed regarding wind tunnel tests. The results of dynamic responses in wind directions were compared to those in the main axes of buildings. The vibration amplitudes in the along- and across-wind directions were closer than those in the two main axes. The relationship between acceleration amplitudes and reduced wind speeds showed a significant effect of the vortex shedding. Additionally, time-varying frequency spectra were used to discuss the modal contribution of the vibration signal. The fundamental frequencies and damping ratios were identified using the SSI method, and correlation analyses were carried out. The relationship between the identified damping ratios and the reduced wind speeds exhibits different aerodynamic effects in the along- and across-wind directions. Comparison of the data showed that dynamic response evaluation in the along- and across-wind directions was more suitable to analyze the wind-resistant performances of super high-rise buildings. All results can aid in understanding the characteristics of these interactions as well as perfect the wind-resistant design of super high-rise buildings.

The Tales of the Philippine Coast Guard Personnel in Responding to the Community Needs

The Philippine Coast Guard personnel experienced a lot of challenges as they put their lives at risk while saving the community against the threat brought by the calamity. One of this life threating incident is the strong typhoon that hits Misamis Occidental. This typhoon gave the people fear in their hearts and mind specially the Philippine Coast Guard Personnel who was the one saving the lives of the community even if it costs their lives. Another incident was also when Super typhoon Odette hit the Philippines. This typhoon was hailed as one of the strongest typhoon that happened in the country that brought torrential rains, strong winds and floods. The study explored the experiences of the Philippine Coast Guard Personnel during their actual rescue or how they respond to the situation during the calamity. There were ten participants who experienced saving lives and properties during calamities served as the participant of the study. Data was obtained through the interview and analyzed through Moustaka’s Transcendental Phenomenological data analysis approach. The generated data from the participants were analyzed and gathered four (4) themes, which include: (1) Motivated to Serve; (2) Prepared to Respond to the Community Needs; (3) Resistant of the Citizens; (4) Job Satisfaction. The government and the community should continue showing their support towards the Philippine Coast Guard organization, especially in times of calamities. The government should conduct a training program for the personnel and also for the community to improve their survival skills. The organization should also conduct survival training or seminars to increase the level of preparedness of the community whenever calamity will arrive.

Experiences, Coping Style, and Concerns of BSVAWA with Super-typhoon Odette

This study was focused on horrible experiences during the super typhoon Odette among Bonbon Small Vendor and Worker Association (BSVAWA) members, a registered women group in Barangay Bonbon. This is an adopted Barangay where (BSVAWA) resides, located near the coastal area of Clarin. The aim of the study was to assess the experiences, coping mechanisms, and concerns with the super typhoon Odette through focus group discussion and coping style survey questionnaire. The researcher concluded the dominating shared experience were terrible fear due to very strong wind and first-time experiences of high-flooding that destroyed their homes and properties. It was concluded that the identified coping style among the BSVAWA members is the Problem-Focused Coping Style which was ranked first with a weighted mean of 3.38 described as a medium amount of coping style which was interpreted as an ideal coping mechanism for stressful situation. Result showed that the major concern of the respondents was in need of a job and livelihood for survival, and most importantly an aid to rebuild their home as one of the physiological needs and safety. The researcher recommends to create a program and activities that would help respondents on their holistic recovery from the unpleasant experience and program to mitigate stress in every natural disaster and improve their health and wellness. This will be a baseline data that will be important for the Local Government Unit of the area.

Typhoon Damage Analysis of Typical Vulnerable Structures

Typhoon, as one of the most devastating natural hazards, has brought billions of property losses and threaten the safety of people around the world, and meanwhile, damage and collapse of various urban structures are the main components of direct losses caused by typhoon. Therefore, the review focus on the introduction on the impact and poster researches about three kinds of typhoon action, external wind pressure, internal wind pressure and wind-borne debris, on the structures at first, and then summarize the failure modes for three kinds of vulnerable structures, including bungalows, light steel industrial buildings and advertisement boards, respectively. Based on the data and field investigations on several severe or super typhoon, the failure modes of those structure start with the places where the elements are lack of potent connection and integrality, such as enclosure members, or the place where the stress concentration appears. This paper is looking forward to giving a assisting the engineers and scientists to improve the typhoon resistance measure or regulate the design of structures to prevent or alleviate the property loss and life security in typhoon in the field of structural analysis. This paper gives the summary on failure mechanism of vulnerable structures, and recommend the reinforcement trend on this field of structures.

Investigation of dynamic properties of tall buildings under super typhoon Mangkhut via Bayesian method

Investigations into the variation law of modal parameters of tall buildings under typhoon events via field measurements have been performed extensively in recent decades. In this study, the dynamic properties of tall buildings under super typhoon Mangkhut are investigated via Bayesian operational modal analysis (BAYOMA), which provides the most probable value and identification uncertainty. First, numerical examples are presented to illustrate the excellent performance of BAYOMA in identifying time-varying structural dynamic properties under colored noise excitations. Subsequently, BAYOMA is performed to identify the modal parameters of two tall buildings with different configurations, namely, the Zhuoyue Century Center (280 m) and Guangzhou West Tower (432 m), using measured acceleration responses atop the buildings under significant structural vibration amplitudes (maximum accelerations of approximately 20 mill-g) during Mangkhut. Variations in the natural frequencies and damping ratios with respect to time and amplitude are investigated and discussed. The identified natural frequencies vary significantly with time. An investigation into the identified natural frequencies vs. the modal root-mean-square shows a negative correlation. Meanwhile, the damping ratios show a large dispersion but remain in the same order of magnitude and do not exhibit significant time-varying and amplitude-dependent features. The aim of this study is to provide further understanding into the in-situ dynamic properties of tall buildings and provide an important reference for wind-resistant design and wind-induced vibration control under severe typhoon conditions.

Characterization of Ionospheric Disturbances Following Multiple Typhoons Using GPS‐Derived TEC

AbstractTyphoon is one of the major hazards in ocean coastal areas, but traditional techniques are inadequate to monitor typhoons due to limited or high‐cost observations, like radio sounding and meteorological radar. Previous studies have found that typhoons can cause ionospheric disturbances, but the relationship and characteristics are still unclear. In this paper, about 400 stations observations of the Global Positioning System (GPS) network in Taiwan are used to extract ionospheric disturbances during multiple typhoons. The detailed characteristics of the ionospheric disturbances are investigated using a fourth‐order Butterworth filter following the 2016 Nepartak, 2019 Lekima, 2019 Mitag, and 2020 Hagupit typhoons. The results show that significant ionospheric disturbances were observed during the typhoons, and the larger disturbances are mostly located 400–1200 km far from the typhoon eye. The estimated horizontal propagation velocity of the ionospheric disturbances is about 127–194 m/s. The locations of the ionospheric disturbances between the typhoon eye and the landfall site are related to the typhoon path. The azimuth distribution of the ionospheric disturbance around the typhoon eye is affected by the GPS elevation angles. At 500–700 km from the typhoon eye, the mean ionospheric disturbances are 0.17 TECU (TEC Unit) and 0.15 TECU for super typhoon Nepartak and Lekima, and 0.13 TECU and 0.18 TECU for typhoon Mitag and Hagupit. The higher the intensity of the typhoon is, the greater the magnitude of the ionospheric disturbance is.

Aberrant white matter microstructure evaluation by automated fiber quantification in typhoon-related post-traumatic stress disorder.

Super typhoons can lead to post-traumatic stress disorder (PTSD), which can adversely affect a person's mental health after a disaster. Neuroimaging studies suggest that patients with PTSD may have post-exposure abnormalities of the white matter. However, little is known about these defects, if they are localized to specific regions of the white matter fibers, or whether they may be potential biomarkers for PTSD. Typhoon survivors with PTSD (n = 27), trauma-exposed controls (TEC) (n = 33), and healthy controls (HCs) (n = 30) were enrolled. We used automated fiber quantification (AFQ) to process the participants' DTI and compared diffusion metrics among the three groups. To evaluate diagnostic value, we used support vector machine (SVM) and a random forest (RF) classifier to build a machine learning model. White matter fiber segmentation between the three groups was found to be statistically significant for the fractional anisotropy (FA) value of the right anterior thalamic radiation (ATR) (26-50 nodes) and right uncinate fasciculus (UF) (60-72 nodes) (FDR correction, p < 0.05). By analyzing the characteristics of the machine learning model, the two most important variables were the right ATR and right UF for differentiating PTSD and trauma-exposed controls (TEC) from the healthy controls (HC). In addition, the left cingulum cingulate and left UF were the most critical variables in the differentiation of PTSD and TEC. AFQ with machine learning can localize abnormalities in specific regions of white matter fibers. These regions may be used as a diagnostic biomarker for PTSD.

Improving Risk Projection and Mapping of Coastal Flood Hazards Caused by Typhoon-Induced Storm Surges and Extreme Sea Levels

Seawater inundation mapping plays a crucial role in climate change adaptation and flooding risk reduction for coastal low-lying areas. This study presents a new elevation model called the digital impermeable surface model (DISM) based on the topographical data acquired by unmanned aerial vehicle (UAVs) for improving seawater inundation mapping. The proposed DISM model, along with the bathtub model, was used to assess coastal vulnerability to flooding in significant tropical cyclone events in a low-lying region of Victoria Harbor in Hong Kong. The inundation simulations were evaluated based on the typhoon news and reports which indicated the actual storm surge flooding conditions. Our findings revealed that the proposed DISM obtains a higher accuracy than the existing digital elevation model (DEM) and the digital surface model (DSM) with a RMSE of 0.035 m. The DISM demonstrated a higher skill than the DEM and the DSM by better accounting for the water-repellent functionality of each geospatial feature and the water inflow under real-life conditions. The inundation simulations affirmed that at least 88.3% of the inundated areas could be recognized successfully in this newly-designed model. Our findings also revealed that accelerating sea level rise in Victoria Harbor may pose a flooding threat comparable to those induced by super typhoons by the end of the 21st century under two representative emission scenarios (RCP4.5 and RCP8.5). The seawater may overtop the existing protective measures and facilities, making it susceptible to flood-related hazards.