DOCSLIB.ORG

High-Resolution Numerical Simulation of Typhoon Longwang (2005) with the Spectrum Nudging Technique

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
High-Resolution Numerical Simulation of Typhoon Longwang (2005) with the Spectrum Nudging Technique Vol.21 No.4 JOURNAL OF TROPICAL METEOROLOGY December 2015 Article ID: 1006-8775(2015) 04-0311-15 HIGH-RESOLUTION NUMERICAL SIMULATION OF TYPHOON LONGWANG (2005) WITH THE SPECTRUM NUDGING TECHNIQUE 1, 2 2 2 LI Jing (李 静) , TANG Jian-ping (汤剑平) , FANG Juan (方 娟) (1. Shanghai Central Meteorological Observatory, Shanghai Meteorological Bureau, Shanghai 200030 China; 2. Key Laboratory of Mesoscale Severe Weather (MOE), School of Atmospheric Sciences, Nanjing University, Nanjing 210043 China) Abstract: With the Weather Research and Forecasting model (WRFV3.2.1), the application of spectrum nudging techniques in numerical simulation of the genesis and development of typhoon Longwang (2005) is evaluated in this work via four numerical experiments with different nudging techniques. It is found that, due to the ability to capture the large-scale fields and to keep the meso-to small-scale features derived from the model dynamics, the experiment with spectrum nudging technique can simulate the formation, intensification and motion of Longwang properly. The improvement on the numerical simulation of Longwang induced by the spectrum nudging depends on the nudging coefficients. A weak spectrum nudging does not make significant improvement on the simulation of Longwang. Although the experiment with four-dimensional data assimilation, i.e., FDDA, also derives the genesis and movement of Longwang appropriately, it fails to simulate the intensifying process of Longwang properly. The reason is that, as the large-scale features derived from the model are nudged to the observational data, the meso- to small-processes produced by the model dynamics important to the intensification of typhoon are nearly smoothed by FDDA. Key words: typhoon; genesis; intensification; spectrum nudging; FDDA CLC number: P444 Document code: A doi: 10.16555/j.1006-8775.2015.04.001 1 INTRODUCTION numerical model, the nudging methods are usually adopted in the numerical simulation. A widely used Along with the development of numerical nudging technique in the numerical model is the calculation techniques and the appearance of traditional nudging, i.e., four-dimensional data high-speed computers, numerical models become an assimilation (FDDA), which is conducted by adding important tool in the studies on tropical cyclones nudging terms in the model equations to reduce the (TCs). To improve the ability of numerical models to deviations of the model-simulated fields from the simulate TCs, many efforts have been made, such as observations (Stauffer and Seaman[13, 14]; Stauffer et increasing the horizontal grid resolution to as much as [15] [1] [2] al. ). Different from FDDA, the spectral nudging to 1 km (Chen et al. ; Menelaou et al. ), modifying [16] [3] technique, proposed by Waldron and then improved the parameterization schemes (Lin et al. ; Ma and by von Storch[17], is conducted by adding nudging Tan[4]; Deshpande et al.[5]), and improving the initial [6] [7] terms in the spectral space. In this way, the conditions (Zou and Xiao ; Zhang et al. ; Yuan et model-derived large-scale fields can be adjusted to be al.[8]; Ma and Tan[9]; Yuan et al.[10]; Liu et al.[11]; [12] close to the observations while the model-simulated Zhang et al. ). meso- to small-scale fields are left unmodified. Due to the vital role of the large-scale Recently, many regional climate models adopt background flow played in the motion and evolution the spectral nudging technique in simulating the of TCs, the appropriate description of the large-scale climatological activity of TCs (Knutson et al.[18]; background circulation in which TC is embedded by Feser and von Storch[19]; Cha et al.[20]; Feser and the numerical model is a precondition of successful Barcikowska[21]; Cao et al.[22]). Knutson et al.[18] simulation of TCs. To ensure that the large-scale showed that a RCM with spectral nudging improved background flow of TCs is properly captured by the the interannual variability of hurricane occurrences by Received 2014-10-20; Revised 2015-08-11; Accepted 2015-10-15 Foundation item: Nature Science Foundation of China (41475046, 41130964); State Key Program of China (2012CB417201) Biography: LI Jing, Assistant Engineer, Shanghai Central Meteorological Observatory, primarily undertaking research on tropical cyclogenesis. Corresponding author: FANG Juan, e-mail: [email protected] 312 Journal of Tropical Meteorology Vol.21 decreasing the number of simulated hurricanes in typhoon in the northwest Pacific in the 2005 typhoon inactive seasons. In Feser and von Storch[19], it is season. In the wake of Saola, there were several found that regional models with spectral nudging can positive vorticity centers. Since the vorticity was improve simulated typhoon developments from global rather weak, no closed cyclonic circulations formed in forcing reanalysis data by giving lower core pressure the wake of Saola. About one day later, the vorticity and higher wind speeds and more realistic strengthened and a closed cyclonic circulation precipitation patterns. In the experiments to evaluate appeared in the wake of Saola. The cyclonic simulated typhoon sensitivities to spectral nudging, circulation enlarged and intensified gradually in the Cha et al.[20] adopted the intermittent spectral nudging next two days and finally developed into a tropical to avoid the suppression that the intensities of depression by 0600 UTC 25 September 2005 simulated typhoons decrease as the spectral nudging (Fig.1b-1d). effect increases while the tracks of simulated Li and Fu[24] argued that TC could induce the typhoons are improved. Recently, Feser and Rossby wave, which might lead to tropical Barcikowska[21] indicated that spectral nudging has cyclogenesis in the wake of the preceding TC via mostly positive effects on typhoon formation, location energy dispersion. To investigate how well the and general circulation patterns in the generation tropical cyclogenesis mechanism proposed by Li et al. areas of TCs. In addition to being used in the (2006) worked in the formation of Longwang, the numerical simulations on the climatological activity signature of Rossby wave was extracted from the of TCs, the spectral nudging method can also be 850-hPa wind fields in the period from 22 to 25 adopted in TC case studies. In Feser and von September 2005 via a 3- to 8-day bandpass filtering Storch[23], the performance of spectral nudging in the following Li and Fu[24]. In the early developing stage construction of a very strong and large typhoon, of Saola, the 3- to 8-day filtered 850-hPa wind fields Winnie (1997), is evaluated. The results indicate that did not exhibit any Rossby wave signals in the wake the spectrum nudging can considerably improve the of Saola because the TC was very weak. From Fig.2a simulation of the motion and evolution of Winnie. we can see that a weak anticyclonic circulation However, due to the relative coarse horizontal grid appeared in the southeast side of Saola at 0600 UTC resolution, i.e., 18 km, the simulation conducted by 22 September. In the following 24 hours, a Feser and von Storch[23] cannot capture the details of northeasterly was considerably enhanced in the east of Winnie evolution and is not good enough for the the anticyclonic circulation and a closed cyclonic studies on the meso-scale processes occurring in the circulation developed gradually in the southeast side evolution of Winnie. of the anticyclonic circulation (Fig.2b and 2c). The In the northwest Pacific, two or more TCs may cyclonic circulation intensified gradually and finally coexist for several days. Under such a circumstance, developed into a tropical depression, i.e., Longwang, successful simulation on TCs becomes difficult. With at 0600 UTC 25 September (Fig.2d). On after the the intention to evaluate the performance of spectral other, the cyclonic, anticyclonic and cyclonic nudging in the numerical simulation of TCs that circulations appeared in the wake of Saola, clearly evolve in an environment with complicated indicating that a Rossby wave train was activated by circulations, a numerical high-resolution simulation of Saola. Obviously, the Rossby wave played an typhoon Longwang (2005) is conducted in this work. important role in the formation of Longwang via The remainder of this paper is organized as follows: offering a low-level cyclonic circulation to trigger the Section 2 presents an overview of the evolution of wind-induced surface heat exchange (WISHE). Typhoon Longwang. Section 3 describes the experiment and methodology. The performance of the spectral nudging in simulation of Longwang is investigated in section 4 and concluding remarks are given in section 5. 2 OVERVIEW ON THE EVOLUTION OF LONGWANG 2.1 Formation of Longwang Figure 1 displays the 850-hPa horizontal streamlines and relative vorticity derived from the NCEP/NCAR reanalysis data in the northwest Pacific during 22-25 September 2005. At 0600 UTC 22 September 2005, a TC, coded Saola, was active at around 25°N, 144°E (Fig.1a), which is the eighteenth 312 No.4 LI Jing (李 静), TANG Jian-ping (汤剑平), et al. 313 Figure 1. The 850-hPa horizontal streamlines and relative vorticity (colored every 2×10-5 s-1) over the tropical Pacific at (a) 0600 UTC 22, (b) 0600 UTC 23, (c) 0600 UTC 24 and (d) 0600 UTC 25 September 2005. The letters “S” and “L” denote typhoon Saola and Longwang, respectively. Figure 2. The 3- to 8-day bandpass-filtered 850-hPa wind fields and 850-hPa wind speed (shaded) at (a) 0600 UTC 22, (b) 0600 313 314 Journal of Tropical Meteorology Vol.21 UTC 23, (c) 0600 UTC 24 and (d) 0600 UTC 25 September 2005. The letters “S” and “L” denote Saola and Longwang, respectively. gradually. 2.2 Intensification of Longwang 2.3 Movement of Longwang Figure 3a displays the time evolution of the minimum sea-level pressure and maximum wind Figure 4a displays the track of Longwang.
Load more

Recommended publications
  • The Eyewall-Penetration Reconnaissance Observation of Typhoon Longwang (2005) with Unmanned Aerial Vehicle, Aerosonde
    JANUARY 2008 L I N A N D L E E 15 The Eyewall-Penetration Reconnaissance Observation of Typhoon Longwang (2005) with Unmanned Aerial Vehicle, Aerosonde PO-HSIUNG LIN AND CHENG-SHANG LEE Department of Atmospheric Sciences, National Taiwan University, Taipei, Taiwan (Manuscript received 18 September 2006, in final form 18 April 2007) ABSTRACT In this paper, a successful eye-penetration reconnaissance flight by an unmanned aerial vehicle, Aerosonde, into Typhoon Longwang (2005) and the preliminary analyses of the collected data are pre- sented. The 10-h flight is diagnosed through four flight legs. The wind field measured along flight leg 1 provides the tangential and radial wind profiles from the outer perimeter into the eye of the typhoon at the 700-hPa layer. A vertical sounding was taken in the eye along flight leg 2 and the derived surface pressure in the eyewall is close to the estimates made by the local weather agencies. Along flight leg 3, the strongest winds during the whole flight mission were measured. These in situ wind measurements by Aerosonde are consistent with the winds observed by the Hua-lien Doppler weather radar. The maximum 10-min (1 min) wind along flight leg 3 when Aerosonde was flying around the eyewall region is 58.6 m sϪ1 (62 m sϪ1). The maximum sustained surface wind derived from this maximum wind speed is also close to the estimates made by the local weather agencies. In conclusion, this successful mission demonstrates that the Aerosonde with a trained crew can play a role in severe weather monitoring and the Aerosonde’s measurement can serve as an independent check for Doppler radar wind retrieval.
    [Show full text]
  • The Eyewall-Penetration Reconnaissance Observation of Typhoon Longwang (2005) with Unmanned Aerial Vehicle, Aerosonde
    JANUARY 2008 L I N A N D L E E 15 The Eyewall-Penetration Reconnaissance Observation of Typhoon Longwang (2005) with Unmanned Aerial Vehicle, Aerosonde PO-HSIUNG LIN AND CHENG-SHANG LEE Department of Atmospheric Sciences, National Taiwan University, Taipei, Taiwan (Manuscript received 18 September 2006, in final form 18 April 2007) ABSTRACT In this paper, a successful eye-penetration reconnaissance flight by an unmanned aerial vehicle, Aerosonde, into Typhoon Longwang (2005) and the preliminary analyses of the collected data are pre- sented. The 10-h flight is diagnosed through four flight legs. The wind field measured along flight leg 1 provides the tangential and radial wind profiles from the outer perimeter into the eye of the typhoon at the 700-hPa layer. A vertical sounding was taken in the eye along flight leg 2 and the derived surface pressure in the eyewall is close to the estimates made by the local weather agencies. Along flight leg 3, the strongest winds during the whole flight mission were measured. These in situ wind measurements by Aerosonde are consistent with the winds observed by the Hua-lien Doppler weather radar. The maximum 10-min (1 min) wind along flight leg 3 when Aerosonde was flying around the eyewall region is 58.6 m sϪ1 (62 m sϪ1). The maximum sustained surface wind derived from this maximum wind speed is also close to the estimates made by the local weather agencies. In conclusion, this successful mission demonstrates that the Aerosonde with a trained crew can play a role in severe weather monitoring and the Aerosonde’s measurement can serve as an independent check for Doppler radar wind retrieval.
    [Show full text]
  • The Impact of Dropwindsonde on Typhoon Track Forecasts in DOTSTAR and T-PARC
    1 Eyewall Evolution of Typhoons Crossing the Philippines and Taiwan: An 2 Observational Study 3 Kun-Hsuan Chou1, Chun-Chieh Wu2, Yuqing Wang3, and Cheng-Hsiang Chih4 4 1Department of Atmospheric Sciences, Chinese Culture University, Taipei, Taiwan 5 2Department of Atmospheric Sciences, National Taiwan University, Taipei, Taiwan 6 3International Pacific Research Center, and Department of Meteorology, University of 7 Hawaii at Manoa, Honolulu, Hawaii 8 4Graduate Institute of Earth Science/Atmospheric Science, Chinese Culture University, 9 Taipei, Taiwan 10 11 12 13 14 Terrestrial, Atmospheric and Oceanic Sciences 15 (For Special Issue on “Typhoon Morakot (2009): Observation, Modeling, and 16 Forecasting Applications”) 17 (Accepted on 10 May, 2011) 18 19 ___________________ 20 Corresponding Author’s address: Kun-Hsuan Chou, Department of Atmospheric Sciences, 21 National Taiwan University, 55, Hwa-Kang Road, Yang-Ming-Shan, Taipei 111, Taiwan. 22 ([email protected]) 1 23 Abstract 24 This study examines the statistical characteristics of the eyewall evolution induced by 25 the landfall process and terrain interaction over Luzon Island of the Philippines and Taiwan. 26 The interesting eyewall evolution processes include the eyewall expansion during landfall, 27 followed by contraction in some cases after re-emergence in the warm ocean. The best 28 track data, advanced satellite microwave imagers, high spatial and temporal 29 ground-observed radar images and rain gauges are utilized to study this unique eyewall 30 evolution process. The large-scale environmental conditions are also examined to 31 investigate the differences between the contracted and non-contracted outer eyewall cases 32 for tropical cyclones that reentered the ocean.
    [Show full text]
  • Analysis on Typhoon Longwang Intensity Changes Over the Ocean Via Satellite Data
    Journal of MarineC.-C. Science Liu etand al .:Technology, Analysis on Vol. Typhoon 17, No. Longwang 1, pp. 23-28 Intensity (2009) Changes Over the Ocean via Satellite Data 23 ANALYSIS ON TYPHOON LONGWANG INTENSITY CHANGES OVER THE OCEAN VIA SATELLITE DATA Chung-Chih Liu*, Tian-Yow Shyu**, Chun-Chieh Chao***, and Yu-Feng Lin*** Key words: typhoon, anticyclonic divergence, radiate. I. INTRODUCTION Typhoons are one of nature’s most destructive weather sys- ABSTRACT tems. Most of them form and develop over the ocean. However, traditional observations are often not sufficient, due to the dif- The changes in the typhoon intensity are a very important ficulty and resources required for the data collection. Thus, process. In this study, we used satellite data to analyze the cloud satellite remote sensing data serves as a much better choice in structure of Typhoon Longwang. Results show that the changes terms of its spatial and temporal resolutions. The geostationary in the high level cirrus pattern seemed to have a connection to meteorological satellite has become an available tool for de- the typhoon intensity. During the time period from 0600UTC to termining the typhoon location, structure and intensity. When 1200UTC 30 September 2005, the high level cirrus clouds of geostationary satellite images were available, the identification Typhoon Longwang radiated from the inner core region. The and tracking of tropical cyclones turned into a trivial task. cloud area that Typhoon Longwang covered grew larger, and the However, many problems still exist in terms of weaker tropical pattern changed from a asymmetric to symmetric distribution cyclones. The scientists at NOAA/NESDIS led by Vern Dvorak during 0000UTC to 1200UTC 30 September 2005.
    [Show full text]
  • Report for Typhoon
    Country Report ( 2007 ) For the 40th Session of the Typhoon Committee ESCAP/WMO Macao, China 21–26 November 2007 People’s Republic of China 1 I. Overview of Meteorological and Hydrological Conditions 1. Meteorological Assessment From Oct. 1st 2006 to Sep. 30th 2007, altogether 23 tropical cyclones (including tropical storms, severe tropical storms, typhoons, severe typhoons and super typhoons) formed over the Western North Pacific and the South China Sea (Fig. 1.1). Among them, 8 TCs formed from Oct. 1st to Dec. 31st in 2006 and 4 of them affected China’s coastal waters but didn’t land on China’s coastal areas. They were super typhoon Cimaron (0619), super typhoon Chebi 0620), super typhoon Durian (0621) and severe typhoon Utor (0622). In 2007, 15 tropical cyclones formed over the Western North Pacific and the South China Sea. The number was obviously less than the average (19.7) during the corresponding period from 1949 to 2006. And 9 of them developed into typhoons or beyond, which accounted for 60.0% of the total. The percentage was higher than the average (58.6%). During the same period, 4 TCs formed over the South China Sea. The number was slightly less than the average (4.7). Moreover, 6 TCs made landfalls over China coastal areas, all of them exceed tropical storm category. They were tropical storm Toraji (0703), severe tropical storm Pabuk 0706), tropical storm Wupit 0707), super typhoon Sepat (0708), super typhoon Wipha 0712) and tropical storm Francisco (0713). The total landed TC number was slightly less than the average (about 6.79), but the percentage of landed TCs (40.0%) was obviously above the average (30.8%).
    [Show full text]
  • Annual Review 2007
    ESCAP/WMO TCAR 2007 Typhoon Committee Over 40 years of InternationalAnnual Cooperation Review Kong-Rey Yutu Toraji Man-Yi Usagi Pabuk Wutip Sepat Fitow Danas Nari Wipha Francisco Lekima Krosa Haiyan Podul Lingling Kajiki Faxai Peipah Tapah Mitag Hagibis ESCAP/ WMO Typhoon Committee 20071 ESCAP/WMO Typhoon Committee Annual Review 2007 On the Cover: MTSAT-1R VS imagery of SEPAT (0708) at 00UTC, 16 August 2007.(By courtesy of Japan Meteorological Agency) The headquarters of the Typhoon Committee Secretariat. 2 TCAR Contents 2007 CONTENTS ESCAP, WMO and the ESCAP/WMO Typhoon Committee 7 Typhoon Committee (2006 – 2007) 9 ESCAP/WMO Typhoon Committee Annual Review 2007 Editorial Board 11 Foreword 13 Introduction 15 Chapter 1 Typhoon Committee Activities 2007 1.1 Meteorology 17 1.2 Hydrology 105 1.3 Disaster Prevention and Preparedness (DPP) 153 1.4 Typhoon Committee Secretariat (TCS) 195 Chapter 2 Tropical Cyclones in 2007 2.1 Overview 197 2.2 Report on individual tropical cyclones which affected Members of the Typhoon Committee 2.2.1 Kong-Rey (0701) 204 2.2.2 Yutu (0702) 206 2.2.3 Toraji (0703) 208 2.2.4 Man-Yi (0704) 210 2.2.5 Usagi (0705) 212 2.2.7 Wutip (0707) 216 2.2.8 Sepat (0708) 218 2.2.9 Fitow (0709) 220 2.2.10 Danas (0710) 222 2.2.11 Nari (0711) 224 2.2.12 Wipha (0712) 226 2.2.13 Francisco (0713) 228 2.2.14 Lekima (0714) 230 2.2.15 Krosa (0715) 232 2.2.16 Haiyan (0716) 234 2.2.17 Podul (0717) 236 2.2.18 Lingling (0718) 238 2.2.19 Kajiki (0719) 240 2.2.20 Faxai (0720) 242 2.2.21 Peipah (0721) 244 2.2.22 Tapah (0722) 246 2.2.23 Mitag (0723) 248 2.2.24 Hagibis (0724) 250 3 ESCAP/WMO Typhoon Committee Annual Review 2007 Chapter 3 Contributed Papers Zhiyu Liu, Bureau of Hydrology, Ministry of Water Resources of China “Mountainous Torrent Disasters and Approaches to Flash Flood Early Warning in China” 253 Mr.
    [Show full text]
  • QPE/QPF) Crowne Plaza Manila Galleria, Quezon City, Philippines 27-30 March 2012
    A Training Course on Quantitative Precipitation Estimation/Forecasting (QPE/QPF) Crowne Plaza Manila Galleria, Quezon City, Philippines 27-30 March 2012 Frequently used QPF techniques and developments Extrapolation, Climatology, Similarity Kuo-Chen Lu Central Weather Bureau, Chinese Taipei Training Course on QPE/QPF Manila 2012 1 contents Introduction Philosophy Synoptic forcing Frontal system Development of forecast guide Typhoon Climatology approach Rain gauge and Grid base Dynamic model approach Development of forecast guide Training Course on QPE/QPF Manila 2012 2 philosophy QPF : is the expected amount of melted precipitation accumulated over a specified time period over a specified area. Amount: Maximum value, or the mean value ? Time period : Hourly, Daily or, A Storm lifespan. Specified Area : A rain gauge, a river basin, A township, A high risk area. How they evaluate QPF ? What’s the reporter said on the newspaper ? They evaluated the QPF is based on the rain gauges. So the forecaster should forecast the value to meet the reporter need, that is based on the rain gauges. Besides, they show the maximum value first. What’s the type of QPF that the user need ? The type of the value should be in the range or in probability. Daily or hourly, the spatial resolution and the duration of request. Training Course on QPE/QPF Manila 2012 3 Forecasting QPF Must determine Where When How Much rainfall will occur area. Must understand the processes that determine the size, scale and intensity of an area of precipitation (synoptic, mesoscale, and even microscale meteorology) Must ..Possess Good Pattern Recognition Skills and understand what gives the pattern the potential to produce significant rainfall Must Possess a working Knowledge of Local Climatology Understand numerical models especially model biases and why they occur Training Course on QPE/QPF Manila 2012 4 Subjectively QPF Analyze situation looking at the synoptic and mesoscale environment.
    [Show full text]
  • Country Report(China).Pdf
    Country Report (2005) For the 38th Session of the Typhoon Committee ESCAP/WMO Hanoi , Vietnam 14 - 19 November 2005 The People’s Republic of China I. Overview of Meteorological and Hydrological Conditions in 2005 1. Meteorological Assessment From October 2004 to October 10 2005, altogether 27 tropical cyclones (including tropical storms, severe tropical storms and typhoons) were formed over the Northwest Pacific and the South China Sea. The total number was basically equivalent to the average (27.49) in 1951-2004. Out of 27, 16 TCs were developed into typhoons, which accounts for 59.26% of the total. In other words, the total typhoon number was slightly less than normal average (17.19 accounting for 62.53%). During the same period, 2 TCs were developed over the waters around the Hainan Province, which were 4.92 less than the multiple-year average. During this period, 10 tropical cyclones made their landfalls over China and they were Typhoon Nock-ten (0424), Typhoon Nanmadol (0427), Typhoon Haitang (0505), severe Tropical Storm Washi (0508), Typhoon Matsa (0509), severe Tropical Storm Sanvu (0510), Typhoon Talim (0513), Typhoon Khanun (0515), Typhoon Damrey (0518) and Typhoon Longwang (0519). The total number was noticeably more than the normal average number (about 7), which accounted for 37.04% of the total in comparison with the average percentage (25.46%). Moreover, in the same period there were another 4 TCs that had affected the coastal waters of China, despite of the fact they did not land over China. These TCs were Typhoon Muiha (0425), Tropical Storm Merbok (0426), Typhoon Nabi (0514) and Tropical Storm Vicente (0516).
    [Show full text]
  • A Long-Lasting Vortex Rossby Wave–Induced Rainband of Typhoon Longwang (2005)
    A Long-Lasting Vortex Rossby Wave–Induced Rainband of Typhoon Longwang (2005) YANLUAN LIN, YUANLONG LI, QINGSHAN LI, MINYAN CHEN, FANGHUA XU, YUQING WANG, AND BIN HUANG n 2 October 2005, a record-breaking rainfall event Tsai 2013). As Typhoon Longwang approached the with 152 mm of rainfall in an hour occurred as coast of Fujian Province at 0800 UTC, one type of this OTyphoon Longwang approached Fujian Province, transient rainband in the northeast sector started to China. The severe rainfall was unexpected and signifi- weaken and dissipate (Fig. 1b). At the same time, the cantly underpredicted by the local weather forecasters eyewall underwent an asymmetry transformation and caused a total of 96 deaths. Because of the severe accompanied by a bended convection pattern in the damage over Taiwan and mainland China, the name north (Fig. 1b). The bended convection transformed of Longwang, which means a dragon in charge of into a strong convective band along the eyewall to the rainfall in Chinese, was removed from the name list north and moved outward relative to the storm center for future typhoons. (Fig. 1c). The convective band continued to intensify with a sharp inner edge (Fig. 1d). An hour later, the EVOLUTION AND BASIC FEATURES OF convective band achieved its maximum intensity with THE RAINBAND. The formation and evolution a large area of stratiform precipitation outward and of the rainband associated with the rainfall event was downstream (Fig. 1e). At this time, cloud brightness captured by the radar mosaic produced by the Central temperatures as low as −80°C were measured by a Weather Bureau (CWB) of Taiwan (Fig.
    [Show full text]
  • Modelling the Effects of Typhoons on Morphological Changes in The
    Continental Shelf Research 135 (2017) 1–13 Contents lists available at ScienceDirect Continental Shelf Research journal homepage: www.elsevier.com/locate/csr ff Modelling the e ects of typhoons on morphological changes in the Estuary MARK of Beinan, Taiwan Wei Po Huang Dept. Harbor and River Engineering, National Taiwan Ocean University, Keelung 20224, Taiwan ARTICLE INFO ABSTRACT Keywords: On average, Taiwan is subjected to three or four typhoon invasions each year. As a typhoon approaches, strong Sediment dynamics ocean waves from the sea, which are accompanied by flash floods on land, can considerably change the Estuarine morphology morphology of estuaries. Thus, knowing the effect of typhoons is important for coastal management. This study Suspended load transport uses simulations and field surveys to analyze the processes of sediment transport near the Beinan Estuary in Typhoon impact southeastern Taiwan. A model that is based on Eulerian and Lagrangian methods is used to simulate sediment Morphological changes transport from fluvial flows, waves, and currents. Typhoons of various intensities, different types of fluvial Wave effect hydrographs, and seasonal effects are used to study their effects on the bathymetry. The relationships among the fluvial sediments, the wave loads, and the evolution of the estuary are derived from the results. The results indicate that the morphology of the Beinan Estuary is governed by typhoon events and that the process of erosion, transport, and deposition of sediment are short. The amount of fluvial sediments that is required to cause changes in the estuary is determined based on these results, and this estimate can be used for erosion protection in the future.
    [Show full text]
  • The Relationship Between the Typhoon Storm in Fujian and Circulation Circumstances
    Journal of Geoscience and Environment Protection, 2018, 6, 277-289 http://www.scirp.org/journal/gep ISSN Online: 2327-4344 ISSN Print: 2327-4336 The Relationship between the Typhoon Storm in Fujian and Circulation Circumstances Jinyu Zeng, Yi Lin, Conghui Gao Fujian Meteorological Observatory, Fuzhou, China How to cite this paper: Zeng, J.Y., Lin, Y. Abstract and Gao, C.H. (2018) The Relationship between the Typhoon Storm in Fujian and The cases of landing and impact of the heavy rain of typhoon in Fujian are Circulation Circumstances. Journal of analyzed. From the research of the mainly weather systems which caused Geoscience and Environment Protection, 6, heavy rain and the distribution characteristics of atmospheric circulation situ- 277-289. https://doi.org/10.4236/gep.2018.64017 ation field, we conclude that on the basis of Fujian special geographical loca- tion and terrain, there are four types (easterly jet, warm-type sheer, inverted Received: March 2, 2018 V-shaped trough of typhoon, westerly trough) are conductive to the circula- Accepted: April 13, 2018 tion patterns of causing the heavy rain of typhoon. Through studying a num- Published: April 16, 2018 ber of typical model cases of heavy rain of typhoon, we can reveal the me- Copyright © 2018 by authors and chanism which causes the heavy rain of typhoon by the mostly influencing Scientific Research Publishing Inc. systems in different circulation backgrounds and the causes of the heavy rain This work is licensed under the Creative of typhoon. Commons Attribution International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ Keywords Open Access Typhoon, Heavy Rain, Circulation Circumstances 1.
    [Show full text]
  • The Challenge of the Slope Failure Problem and Its Remedial Considerations at Mileage 39Km, Mt. Ali Road, Taiwan
    The Challenge of the Slope Failure Problem and Its Remedial Considerations at Mileage 39km, Mt. Ali Road, Taiwan Le défi du problème du glissement de pente et des dispositions correctives apportées, au kilomètre 39, de la route Mt. Ali Road, àTaïwan Chang M., Huang R. National Yunlin University of Sci. & Tech., Taiwan ABSTRACT: Mt. Ali Road is a main scenic route to Alishan National Scenic Area and Yushan National Park in the middle of Taiwan. At Mileage 39Km, the downslope side of the road consists of a 200m deep 60° angle bare cliff with a creek passing around the slope’s toe. Despite complex geologic conditions, the underlying slope materials appeared competent for about 20 years after the road opening. In 1999, however, a severe earthquake (Chi-Chi, Mw = 7.6) hit central Taiwan and caused numerous landslips in the mountain range of the island. Although no obvious damages to the road were observed after the time of shaking, the geologic setting of the site was deteriorating. During the attack of Typhoon Nari in 2001, the first serious effect on the road appeared and caused several parallel cracks along the alignment. Remedial work was initiated. Nonetheless, a loss of road base during the monsoon season next year had called for a stop of the work. The remedial plan was revised and implemented, but failed again due to Typhoons Talim and Longwang in 2005. The current repair works have been completed and generally show no major signs of slope distress. In view of repair histories and the geologic setting, this paper discusses the concerns and challenges for long-term stability of slopes at the site.
    [Show full text]