Typhoon

Typhoon Yolanda brought death and devastation, leaving over four million people displaced and over a million homes destroyed. Progress to rebuild and resettle homeless inhabitants has been made since a new phase of recovery commenced from 2015. Large infrastructure projects have been undertaken, or are ongoing; and an extensive number of public and private relocation shelters have been erected. Many people who lost their homes have new ones. Local buildings-barangay halls (the barangay is the smallest political unit with elected officials), multipurpose buildings, Communities are slowly being rebuilt after Super Typhoon Yolanda (also known as Typhoon Haiyan) struck the Visayas Islands in the Philippines in November 2013. The vulnerable, most affected communities face ongoing challenges to re-establish livelihoods, safe housing, access to water and electricity, and to rebuild roads and drainage. Aid agencies, active on the ground in the immediate aftermath, have since left the region, leaving national and local government, policymakers and affected communities to respond to the long-term legacy. Researchers at the University of Nottingham, UK and Ningbo, China in partnership with the University of the Philippines, Diliman have worked closely with local communities to articulate the lessons from Typhoon Yolanda. Their recommendations for national and local policymakers and government officials, civil society groups, and foreign aid agencies involved in future disaster work show signs of adoption as agencies take on board the importance of engaging affected communities in recovery and rehabilitation plans. Cover photo: Communities attempt to rebuild their lives amidst the debris left behind by Typhoon Yolanda.

In this study, the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5) with three-dimensional variational data assimilation (3DVAR) is utilized to investigate influences of GPS occultation refractivity on simulations of typhoons past Taiwan. Two recent cases were simulated, including Typhoon Nari in September 2001 and Typhoon Nakri in July 2002. The GPS observation data are taken from the Challenging Minisatellite Payload for Geophysical Research and Application (CHAMP) and Satélite de Aplicaciones Científicas-C (SAC-C) satellites that provide several retrieved refractivity profiles in the simulated domain near the initialization time. Through 3DVAR, the observed refractivity can be quickly ingested into the model initial conditions to recover the information over the ocean. The initial moisture increments from ingested GPS refractivity soundings exhibit a maximum magnitude of about 1.5 g kg−1 associated with temperature incr...

1] In recent years, the population and the value of properties in areas prone to tropical cyclone (TC) have increased dramatically. This has caused more attention to be placed on the characterization of TC climatologies and the identification of the role that factors such as the main teleconnection patterns may play in TC variability. Due to the timescales involved, the instrumental records have proven too short to provide a complete picture. Thus, documentary and other paleoclimatological techniques have been used to reconstruct TC occurrence. This has been done mostly for the Atlantic basin, whereas in the Pacific basin, fewer attempts have been made. The aim of this paper is to provide a high-resolution chronology of typhoons and intense storms occurring in the Philippine Islands and their vicinity for the period 1566-1900. The chronology is based upon the writings of the Spanish Jesuit Miguel Selga, who produced the original work at the beginning of the 20th century. The sources, reliability, and completeness of the chronology are examined critically. A total of 652 events are included, 524 of which are reported as typhoons, the rest being considered as tropical storms. For each of these classes, the landfall location and the track (when sufficient information is available) have been drawn. This chronology is an indispensable step toward a final and complete typhoon record in the western Pacific basin.

Strong winds and storm surges from Typhoon Haiyan caused damage of US$12–15 billion and N10,000 human casualties in central Philippines in November 2013. To validate a proposed government US$22 million mangrove replanting program, mangrove damage and short-term recovery were surveyed in seven natural and planted mangrove sites in Eastern Samar province at 2.5 month and 4.5 month post-Haiyan. The preliminary assessment showed that natural mangroves (except for those directly hit by the storm) were recovering by means of tree sprouts and surviving seedlings and saplings compared to the devastated plantation. Likewise, tree mortality was higher in the plantation and natural forests hit by the storm surge, compared to more undamaged and partially damaged trees in natural mangroves. Hence the main recommendations to government are (1) to protect recovering mangroves by not releasing rehabilitation funds (that will inadvertently pay for clearing of live trees and for removal of seedlings), (2) to only plant in totally damaged sites (e.g., plantations), and (3) to only plant naturally dominant species, e.g., Sonneratia alba and Avicennia marina (instead of the popular Rhizophora apiculata, R. mucronata and R. stylosa).

Delivering accurate cyclone forecasts in time is of key importance when it comes to saving human lives and reducing economic loss. Difficulties arise because the geographical and climatological characteristics of the various cyclone formation basins are not similar, which entails that a single forecasting technique cannot yield reliable performance in all ocean basins. For this reason, global forecasting techniques need to be applied together with basin-specific techniques to increase the forecast accuracy. As cyclone track is governed by a range of factors variations in weather conditions, wind pressure, sea surface temperature, air temperature, ocean currents, and the earth' rotational force-the coriolis force, it is a formidable task to combine these parameters and produce reliable and accurate forecasts. In recent years, the availability of suitable data has increased and more advanced forecasting techniques have been developed, in addition to old techniques having been modified. In particular, artificial neural network based techniques are now being considered at meteorological offices. This new technique uses freely available satellite images as input, can be run on standard PCs, and can produce forecasts with good accuracy. For these reasons, artificial neural network based techniques seem especially suited for developing countries which have limited capacity to forecast cyclones and where human casualties are the highest.

Coral reefs in Eastern Samar, Philippines were badly damaged by super typhoon Haiyan, which left many reefs in a fragmented state-with many branching corals and other coral forms scattered in loose pieces. As part of the efforts to address this problem, we tested the re-attachment of 43 species of coral fragments to sturdy natural substrates in three reef sites in Eastern Samar (Can-usod and Monbon in Lawaan, and Panaloytoyon in Quinapondan). The results revealed that 88% of re-attached coral fragments survived (45% showed positive growth, and 43% survived with partial tissue mortality). Those that showed positive growth exhibited high growth rates. We also found that fragments of some coral species are more fast-growing (e.g., Cyphastrea decadia, Echinopora pacificus, and Millepora tenella) than others (e.g., Porites lobata or Pectinia paeonia). Overall, our results suggest that if Local Government Units (LGUs) invest in the re-attachment of fragmented corals (e.g., reefs damaged by super typhoons or by various human activities such as fishing), then coral reef degradation in the Philippines would have a better chance of recovering.

Starting from 2003, a new typhoon surveillance program, Dropwindsonde Observations for Typhoon Surveillance near the Taiwan Region (DOTSTAR), was launched. During 2004, 10 missions for eight typhoons were conducted successfully with 155 dropwindsondes deployed. In this study, the impact of these dropwindsonde data on tropical cyclone track forecasts has been evaluated with five models (four operational and one research models). All models, except the Geophysical Fluid Dynamics Laboratory (GFDL) hurricane model, show the positive impact that the dropwindsonde data have on tropical cyclone track forecasts. During the first 72 h, the mean track error reductions in the National Centers for Environmental Prediction's (NCEP) Global Forecast System (GFS), the Navy Operational Global Atmospheric Prediction System (NOGAPS) of the Fleet Numerical Meteorology and Oceanography Center (FNMOC), and the Japanese Meteorological Agency (JMA) Global Spectral Model (GSM) are 14%, 14%, and 19%, respectively. The track error reduction in the Weather Research and Forecasting (WRF) model, in which the initial conditions are directly interpolated from the operational GFS forecast, is 16%. However, the mean track improvement in the GFDL model is a statistically insignificant 3%. The 72-h-average track error reduction from the ensemble mean of the above three global models is 22%, which is consistent with the track forecast improvement in Atlantic tropical cyclones from surveillance missions. In all, despite the fact that the impact of the dropwindsonde data is not statistically significant due to the limited number of DOTSTAR cases in 2004, the overall added value of the dropwindsonde data in improving typhoon track forecasts over the western North Pacific is encouraging. Further progress in the targeted observations of the dropwindsonde surveillances and satellite data, and in the modeling and data assimilation system, is expected to lead to even greater improvement in tropical cyclone track forecasts.

At this point, Japan is being attacked by a super typhoon, but my bubble has protected the area that far exceeds my area. The color has changed and is easy to understand.
BUBBLE TECH IS PROVING THAT US HUMANS COLLECTIVELY ARE THE CREATOR GODS OF ALL THAT WE SEE.

This study examines the dynamics which lead to revitalization of everyday life in the public spaces of Cagayan de Oro, a medium-sized urban center in Northern Mindanao, the Philippines. By employing the oriental philosophies together with western thoughts such as Henri Lefebvre, Alain Touraine and Jurgen Habermas, this study elucidates that the core of perceived, lived and conceived spaces is ‘the Subject.’ Once the Subject utilizes the public sphere to instill social action, social space is ultimately produced. Hawkers, grassroots environmental activists, street readers and artists are the social Subjects who partake in the vibrancy of public spaces. The social Subjects utilize public spaces as venues of social transformation. Thus, this study argues that the social Subjects’ role in democratic process lead to inclusivity of the marginalized sector in the public spaces of the city.

Journal of Oceanography, Vol. 58, pp. 137 to 151, 2002 Review Microwave Remote Sensing of Tropical Cyclones from Space Kristina В. Katsaros1*, Paris W. Vachon2, W. Timothy Liu3 and Peter G. Black1 1 NOAA/Atlantic Océanographie and Meteorological Laboratory, 4301 ...

Strong winds and storm surges from Typhoon Haiyan caused damage of US$12-15billion and >10,000 human casualties in central Philippines in November 2013. To validate a proposed government US$22million mangrove replanting program, mangrove damage and short-term recovery were surveyed in seven natural and planted mangrove sites in Eastern Samar province at 2.5month and 4.5month post-Haiyan. The preliminary assessment showed that natural mangroves (except for those directly hit by the storm) were recovering by means of tree sprouts and surviving seedlings and saplings compared to the devastated plantation. Likewise, tree mortality was higher in the plantation and natural forests hit by the storm surge, compared to more undamaged and partially damaged trees in natural mangroves. Hence the main recommendations to government are (1) to protect recovering mangroves by not releasing rehabilitation funds (that will inadvertently pay for clearing of live trees and for removal of seedlings), (2) to only plant in totally damaged sites (e.g., plantations), and (3) to only plant naturally dominant species, e.g., Sonneratia alba and Avicennia marina (instead of the popular Rhizophora apiculata, R. mucronata and R. stylosa).

The Northwest Pacific Ocean (NWP) is one of the most vulnerable regions that has been hit by typhoons. In September 2018, Mangkhut was the 22nd Tropical Cyclone (TC) over the NWP regions (so, the event was numbered as 1822). In this paper, we investigated the highest amplitude ionospheric variations, along with the atmospheric anomalies, such as the sea-level pressure, Mangkhut's cloud system, and the meridional and zonal wind during the typhoon. Regional Iono-sphere Maps (RIMs) were created through the Hong Kong Continuously Operating Reference Stations (HKCORS) and International GNSS Service (IGS) data around the area of Mangkhut typhoon. RIMs were utilized to analyze the ionospheric Total Electron Content (TEC) response over the maximum wind speed points (maximum spots) under the meticulous observations of the solar-terrestrial environment and geomagnetic storm indices. Ionospheric vertical TEC (VTEC) time sequences over the maximum spots are detected by three methods: interquartile range method (IQR), enhanced average difference (EAD), and range of ten days (RTD) during the super typhoon Mangkhut. The research findings indicated significant ionospheric variations over the maximum spots during this powerful tropical cyclone within a few hours before the extreme wind speed. Moreover, the ionosphere showed a positive response where the maximum VTEC amplitude variations coincided with the cyclone rainbands or typhoon edges rather than the center of the storm. The sea-level pressure tends to decrease around the typhoon periphery, and the highest ionospheric VTEC amplitude was observed when the low-pressure cell covers the largest area. The possible mechanism of the ionospheric response is based on strong convective cells that create the gravity waves over tropical cyclones. Moreover, the critical change state in the meridional wind happened on the same day of maximum ionospheric variations on the 256th day of the year (DOY 256). This comprehensive analysis suggests that the meridional winds and their resulting waves may contribute in one way or another to upper atmosphere-ionosphere coupling.

Both Argo measurements and satellite sea surface temperature (SST) data revealed that there was less-than-usual surface cooling during the passage of typhoons Kaemi and Cimaron in the tropical Northwest Pacific. In the present study, it is found that SST cooling induced by typhoon can be greatly suppressed by a barrier layer with a thickness of 5-15 m. Such a barrier layer could reduce the entrainment cooling by 0.4-0.8 • C/d during typhoon passage, according to a diagnostic mixed layer model. The pre-existing barrier layer leads to a reduction in typhoon-induced surface cooling, and favors typhoon development. The average SST anomaly under barrier layer condition is 0.4-0.8 • C less than that under no-barrierlayer condition. Due to the reduced cooling, the available maximum potential intensity (MPI) under barrier layer condition are higher 6 and 9.34 m/s than those under no-barrier-layer condition according to SST-dependent MPI formulation for Kaemi and Cimaron. In addition, the results from Price-Weller-Pinkel (PWP) model indicate that stratification due to salinity may significantly influence both entrainment and the upper ocean heat content during typhoon passage in the tropical Northwest Pacific.

The litterfall in a subtropical broadleaf forest within the Fushan Experimental Forest in northeastern Taiwan was monitored for 9 years. Mean annual litterfall was very sensitive to typhoon frequency and intensity, ranging from 3 to 11 Mg·ha -1 ·year -1 . Litterfall was significantly higher in years with strong typhoons than in years without typhoons, and the number of strong typhoons explained 82% of interannual variation in litterfall. Nutrient-use efficiency (dry mass/nutrients in litterfall) was high for N, but low for P compared with other tropical forests. This result supports the idea that the study forest is P limited but not N limited. Nutrient loss via litterfall represents a large percentage of aboveground biomass, especially during years with strong typhoons (e.g., 19%-41%, 15%-40%, 5%-12%, for N, P, and K, respectively). Forests that experience infrequent wind disturbance (e.g., temperate or boreal forests) can gradually regain any lost nutrients prior to the next disturbance; this is different from the situation observed in the Fushan Experimental Forest. At Fu-shan the pattern of not responding to typhoons with a flush of new growth appears to be an adaptation to the frequency with which there are multiple typhoons affecting the forest in a single year. Nutrient loss in litterfall caused by frequent typhoon disturbances appears to limit tree growth and contributes to the very low canopy height of the Fushan Experimental Forest.

Forecasting of a typhoon moving path may help to evaluate the potential negative impacts in the neighbourhood areas along the moving path. This study proposed a work of using both static and dynamic neural network models to link a time series of typhoon track parameters including longitude and latitude of the typhoon central location, cyclonic radius, central wind speed, and typhoon moving speed. Based on the historical records of 100 typhoons, the performances of neural network models are evaluated from the indices of a correlation coefficient and a mean square error. The dynamic model or the so-called nonlinear autoregressive network with the use of a moving average method proved to forecast the ten types of typhoon moving path more effectively in Taiwan region. The new and simply approach developed in this study for solving studied typhoon cases may be applicable to other areas of interest worldwide..

Space geodetic applications require to model troposphere delays as good as possible in order to achieve highly accurate positioning estimates. However, these models are not capable to consider complex refractivity fields which are likely to occur during extreme weather situations like typhoons, storms, heavy rain-fall, etc. Thus it has been investigated how positioning results can be improved if information from numerical weather models is taken into account. It will be demonstrated that positioning errors can be significantly reduced by the usage of ray-traced slant delays. Therefore, mesoscale and fine-mesh numerical weather models are utilized and their impact on the positioning results will be measured. The approach has been evaluated during a typhoon passage using global positioning service (GPS) observations of 72 receivers located around Tokyo, proving the usefulness of ray-traced slant delays for positioning applications. Thereby, it is possible reduce virtual station movements as well as improve station height repeatabilities by up to 30% w.r.t. standard processing techniques. Additionally the advantages and caveats of numerical weather models will be discussed and it will be shown how fine-mesh numerical weather models, which are restricted in their spatial extent, have to be handled in order to provide useful corrections.

P min minimum typhoon center atmospheric pressure R(t) typhoon seventh-grade-wind storm radius R max maximum storm radius of R(t) r correlation coefficient t time U(t) typhoon near-center wind speed U max maximum wind speed of U(t) Y(t) astronomical tidal level w i angular frequencies of component tides h(t)

This study explores the possibility of reconstructing the weather of Southeast Asia for the last decades using an atmospheric regional climate model, the Climate version of the Lokal-Modell (CLM). For this purpose global National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) reanalyses data were dynamically downscaled to 50 km and in a double-nesting approach to 18-km grid distance. To prevent the regional model from deviating significantly from the reanalyses with respect to large-scale circulation and large-scale weather phenomena, a spectral nudging technique was used. The performance of this technique in dealing with Southeast Asian typhoons is now examined by considering an ensemble of one simulated typhoon case. This analysis is new insofar as it deals with simulations done in the climate mode (so that any skill of reproducing the typhoon is not related to details of initial conditions), is done in ensemble mode (the same development is described by several simulations), and is done with a spectral nudging constraint (so that the observed large-scale state is enforced in the model domain). This case indicates that tropical storms that are coarsely described by the reanalyses are correctly identified and tracked; considerably deeper core pressure and higher wind speeds are simulated compared to the driving reanalyses. When the regional atmospheric model is run without spectral nudging, significant intraensemble variability occurs; also additional, nonobserved typhoons form. Thus, the insufficiency of lateral boundary conditions alone for determining the details of the dynamic developments in the interior becomes very clear. The same lateral boundary conditions are consistent with different developments in the interior. Several sensitivity experiments were performed concerning varied grid distances, different initial starting dates of the simulations, and changed spectral nudging parameters.

So I came and conquered this beautiful island and felt like a winner of a lottery after seeing its heavenly features-both the blue sea and the blue sky looks the same in my eyes, the wind keeps on brushing off my hair, the sun shines so bright featuring the beauty of the surroundings, the white sand complements the crystal clear waters; the beautiful, paradise island was totally ready for me. The island is so peaceful and serene until darkness took over its beauty

農作物生產過程遭受強風吹襲而造成損失，防風網的利用是一種低成本及施作簡易
之防災策略。本研究擬建立由計算流體力學(CFD) 評估最適化防風網架設條件，作為提
供農作物防風技術之參考依據。試驗結果顯示，試驗田區架設不同網目及高度之防風
網，由實測風速變化以驗證CFD 模擬能力，結果顯示CFD模擬值與實際風場通過防風網
之減弱趨勢相符，可準確掌握風速流場，做為評估防風網效能之有效工具。另由評估結
果，防風網最佳阻風有效長度，水平距離為防風網高度之6 倍，有效高度為防風網高度
之1.3 倍。另由實際防風網在颱風期間之阻風效果案例分析，以70%百吉網阻風率可將18
m s-1 最大陣風降至4 m s-1，防風效果顯著。

An interesting eyewall evolution occurred in Typhoon Zeb (1998) when it devastated Luzon. The eyewall of Zeb contracted before landfall and broke down and weakened after landfall; then a much larger new eyewall formed and strengthened as it left Luzon and reentered the ocean. The fifth-generation Pennsylvania State University-NCAR Mesoscale Model (MM5) with four nested domains was used to perform numerical experiments to understand the effects of terrain and land surface variation on the observed eyewall evolution. Results show that the presence of Luzon plays a critical role in the observed eyewall evolution. Quite different from the conventional concentric eyewall replacement, the eyewall replacement that occurred in Typhoon Zeb was triggered by the mesoscale landmass and terrain variation with a horizontal scale similar to the core of the typhoon. In Typhoon Zeb, the original eyewall contracted and broke down because of enhanced surface friction after landfall. The outer eyewall was triggered by convective rainbands near the western coastal region of Luzon and formed as a result of axisymmetrization well after the dissipation of the inner eyewall convection.

The Intergovernmental Panel on Climate Change predicts dramatic changes in precipitation patterns over the next century. One potential method for inferring how these changes in annual precipitation and intensity of storm events will influence aquatic ecosystems is to study and model present-day lakes that share climatic characteristics with future climate scenarios. A small lake in north-central Taiwan provided an excellent opportunity to explore the influence of intense meteorological events on CO 2 exchange between surface waters and the atmosphere. Each year Yuan Yang Lake (YYL) is influenced by multiple typhoons that pass near the island of Taiwan. This lake has been instrumented with a sensor network that monitors water column and meteorological parameters at a high temporal resolution (2-10 min intervals). Using this highresolution data and manually collected CO 2 samples, a mass-balance model of CO 2 dynamics in YYL was developed. In addition, a generalized simulation model was used to explore how typhoon frequency, intensity, and timing impact CO 2 efflux to the atmosphere. Our findings suggest that increased annual precipitation and frequency of storm events results in greater epilimnetic interaction with the watershed and hypolimnion. These interactions resulted in elevated epilimetic CO 2 concentrations and therefore greater evasion of CO 2 to the atmosphere.

Due to the 2009 flood brought by Typhoon Ondoy, relief operations were done through the partnership of a humanitarian organization and the academe. The engagement of the academe was deemed important to document and draw lessons from the experience in emergency response. This paper examines the experience on disaster relief operations. It looks at the processes, good practices, challenges and issues faced during the provision of relief goods from needs assessment, pre-distribution preparation, actual distribution and post-distribution activities. The paper provides insights in improving practices in disaster relief operations that can contribute to more humane processes, better interpersonal relations and substantial impact.

Asian countries strongly depend on rice production for food security. The major rice-growing season (June to October) is highly exposed to the risk of tropical storm related damage. Unbiased and transparent approaches to assess the risk of rice crop damage are essential to support mitigation and disaster response strategies in the region. This study describes and demonstrates a method for rapid, pre-event crop status assessment. The ex-post test case is Typhoon Haiyan and its impact on the rice crop in Leyte Province in the Philippines. A synthetic aperture radar (SAR) derived rice area map was used to delineate the area at risk while crop status at the moment of typhoon landfall was estimated from specific time series analysis of Moderate Resolution Imaging Spectroradiometer (MODIS) data. A spatially explicit indicator of risk of standing crop loss was calculated as the time

We quantified mangrove disturbance resulting from Super Typhoon Haiyan using a remote sensing approach. Mangrove areas were mapped prior to Haiyan using 30m Landsat imagery and a supervised decision-tree classification. A time sequence of 250m eMODIS data was used to monitor mangrove condition prior to, and following, Haiyan. Based on differences in eMODIS NDVI observations before and after the storm, we classified mangrove into three damage level categories: minimal, moderate, or severe. Mangrove damage in terms of extent and severity was greatest where Haiyan first made landfall on Eastern Samar and Western Samar provinces and lessened westward corresponding with decreasing storm intensity as Haiyan tracked from east to west across the Visayas region of the Philippines. However, within 18months following Haiyan, mangrove areas classified as severely, moderately, and minimally damaged decreased by 90%, 81%, and 57%, respectively, indicating mangroves resilience to powerful typhoons.

Remotely-sensed sea surface temperature (SST) and chlorophyll data were used to assess the biological response to the Typhoon Megi in the Japan/East Sea (JES). Mean SST from in situ measurements and satellite data decreased by about 2-4°C in the JES after Typhoon Megi. Mean concentration of MODIS chlorophyll in the post-typhoon period increased by about 70% along the typhoon passage. The cold, nutrient-rich waters entrained into the surface layer lead to an enhancement of phytoplankton growth. Typhoon-induced variability of nitrate, phosphate, and silicate at the sea surface of the JES were derived from the MODIS SST using a nutrient-temperature relationship based on in situ measurements. After the passage of the typhoon, there were increases in NO 3 , PO 4 , and SiO 2 by about 90%, 40%, and 35%, respectively. The nutrient flux brought into the surface water by the storm-induced mixing has the potential to support new production.

1] Isotope ratios of precipitation and water vapor were observed during the passage of Typhoon Shanshan at Ishigaki Island, southwestern Japan, on 15-16 September 2006. Such high-resolution isotopic observations allow for qualitative understanding of atmospheric moisture cycling; they revealed that isotope ratios of both the precipitation and water vapor decreased radially inward in the cyclone's outer region; anomalously high isotope ratios appeared in the cyclone's inner region; and d-excess tended to decrease in the cyclone's inner region. In the cyclone's outer region, the water vapor was isotopically depleted due to the rainout effect which involves both condensation efficiency as reflected in inwardly increasing cloud thickness and isotopic exchange between falling droplets and the ambient water vapor. In contrast, water vapor in the cyclone's inner region was isotopically enriched due to weak rainout effect in conjunction with intensive isotopic recharge from the sea spray and sea surface with heavy isotope ratios. Since water vapor mainly acts as a source of precipitation, the isotope ratios of precipitation also had systematic variation. A unique circumstance is the intensity of isotopic exchange with almost saturated surface air and high winds, causing anomalously high isotope ratios and low d-excess values in the cyclone's inner region.

Landfalling tropical cyclones (TCs) often bring about heavy rainfall, which typically decreases with the weakening of the TCs. However, some TCs may suddenly be reinvigorated after they become remnants over land. Such TCs may produce even stronger rains than those at the time of their landfall. This reinvigorating phenomenon is known as ''rainfall reinforcement associated with landfalling tropical cyclones'' (RRLTC). The TCs triggering rainfall reinforcement account for 9.7% of the total number of TCs that make landfall on mainland China and often cause problems and surprises for forecasters. The TCs with rainfall reinforcement mostly make landfall in the area of the southeastern coast of China and move primarily along two tracks, spreading northward or westward. RRLTC often occurs in the remnant of a tropical depression that has already been downgraded from typhoon intensity, particularly in a period when the remnant has slowed down or even stagnated. The highest frequency of RRLTC occurrence is during the third day after landfall and in the northeast quadrant of a TC moving northward and the southwest quadrants of a TC moving westward.

A coupled model has been developed to simulate, at watershed level, landslides and debris flows induced by a severe typhoon (tropical cyclone) in Taiwan. The model comprises a landslide susceptibility model to predict landslide occurrence, an empirical model to select debris-flow initiation points, and a debris flow model to simulate the transport and deposit of failed materials from the identified source areas. In raster format with a 10 m spatial resolution, the model output includes unstable cells, debris-flow initiation cells, debrisflow velocities, runout paths, and deposition zones. The model was first tested and calibrated in a small area, where the damage by landslides had been investigated and recorded. It was then applied to a watershed, and the simulation results were validated by comparing them with a landslide/debris-flow inventory map prepared from satellite images using a multiple change detection technique. Model test and validation results confirm the usefulness of the model in predicting the number and size of affected areas (landslides and runouts combined), runout path, and volume of runout deposits. It is a common practice in Taiwan to separate landslide and debris-flow inventories and to study debris flows only in select drainage basins. This study suggests that landslide and debris flow should be modeled as a sequential process for efficient watershed management.

When Typhoon Songda (2004) was located southeast of Okinawa over the western North Pacific during 2-4 September 2004, a heavy rainfall event occurred over southern central Japan and its adjacent seas, more than 1200 km from the typhoon center. The Advanced Research version of the Weather Research and Forecast (WRF-ARW) model was used to investigate the possible remote effects of Typhoon Songda on this heavy precipitation event in Japan. The National Centers for Environmental Prediction (NCEP) global final (FNL) analysis was used to provide both the initial and lateral boundary conditions for the WRF model. The model was initialized at 1800 UTC 2 September and integrated until 1800 UTC 6 September 2004, during which Songda was a supertyphoon. Two primary numerical experiments were performed. In the control experiment, a bogus vortex was inserted into the FNL analysis to enhance the initial storm intensity such that the model typhoon had an intensity that was similar to that observed at the initial time. In the no-typhoon experiment, the vortex associated with Typhoon Songda in the FNL analysis was removed by a smoothing algorithm such that the typhoon signal did not appear at the initial time. As verified against various observations, the control experiment captured reasonably well the evolution of the storm and the spatial distribution and evolution of the precipitation, whereas the remote precipitation in Japan was largely suppressed in the no-typhoon experiment, indicting the significant far-reaching effects of Typhoon Songda. Songda enhanced the remote precipitation in Japan mainly through northward moisture transport into the preconditioned precipitation region by its outer circulation. The orographic forcing of the central mountains in Japan played a small role compared with Typhoon Songda in this extreme precipitation event.