DOCSLIB.ORG

Downloaded 10/05/21 02:09 PM UTC 1426 WEATHER and FORECASTING VOLUME 29

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Downloaded 10/05/21 02:09 PM UTC 1426 WEATHER and FORECASTING VOLUME 29 DECEMBER 2014 W E I 1425 Surface Wind Nowcasting in the Penghu Islands Based on Classified Typhoon Tracks and the Effects of the Central Mountain Range of Taiwan CHIH-CHIANG WEI Department of Digital Content Designs and Management, Toko University, Pu-Tzu City, Chia-Yi County, Taiwan (Manuscript received 5 March 2014, in final form 21 September 2014) ABSTRACT The purposes of this study were to forecast the hourly typhoon wind velocity over the Penghu Islands, and to discuss the effects of the terrain of the Central Mountain Range (CMR) of Taiwan over the Penghu Islands based on typhoon tracks. On average, a destructive typhoon hits the Penghu Islands every 15–20 yr. As a typhoon approaches the Penghu Islands, its track and intensity are influenced by the CMR topography. Therefore, CMR complicates the wind forecast of the Penghu Islands. Six main typhoon tracks (classes I–VI) are classified based on typhoon directions, as follows: (I) the direction of direct westward movement across the CMR of Taiwan, (II) the direction of northward movement along the eastern coast of Taiwan, (III) the direction of northward movement traveling through Taiwan Strait, (IV) the direction of westward movement traveling through Luzon Strait, (V) the direction of westward movement traveling through the southern East China Sea (near northern Taiwan), and (VI) the irregular track direction. The adaptive network-based fuzzy inference system (ANFIS) and multilayer perceptron neural network (MLPNN) were used as the forecasting technique for predicting the wind velocity. A total of 49 typhoons from 2000 to 2012 were analyzed. Results showed that the ANFIS models provided high-reliability predictions for wind velocity, and the ANFIS achieved more favorable performance than did the MLPNN. In addition, a de- tailed discussion on the interaction of the CMR with the Penghu Islands based on various track directions is provided. For class I, the CMR is observed to have significantly influenced variations in wind speed when typhoons approached the Penghu Islands. In addition, the winds on the Penghu Islands were ob- served to have been influenced by the distance from the typhoon center to the Penghu Islands for all classes except class II. 1. Introduction a destructive typhoon hits the Penghu Islands every 15– 20 yr (Wu et al. 2013). For the Penghu Islands, the wind The Penghu Islands (Fig. 1), situated in the main path data were measured by a weather station at an eleva- of western North Pacific typhoons, form an archipelago tion of 10 m above sea level, indicating highly fluctu- off the western coast of Taiwan in the Taiwan Strait. The ating wind velocities during typhoons, as evidenced Penghu Islands comprise excellent land and sea areas for by historical records. Compared with weather stations wind power generation. Recently, the Penghu Islands at this altitude, a typical wind turbine, which is ap- were selected as low-carbon islands because numerous proximately 40–60 m in height, might be subjected to researchers have found the Penghu Islands to be an relatively stronger winds. Because fluctuations in wind excellent location for developing wind power (Lee and velocity influence wind power production, accurate Huang 2004; Lin 2012). Wind power meteorology can knowledge of wind is required for the planning, design, provide information to the wind power industry over and operation of wind turbines (Akhmatov 2007; the Penghu Islands, such as the siting of wind tur- Vincentetal.2010). bines, regional wind resource assessment, and the short- As a typhoon approaches the Penghu Islands, the ty- term prediction of wind resources (Petersen et al. 1998; phoon circulation with the Central Mountain Range Hsieh and Dai 2012). According to typhoon statistics, (CMR) of Taiwan, as indicated by the yellow dotted line in Fig. 1, produces considerable mesoscale variations in Corresponding author address: Chih-Chiang Wei, No. 51, Sec. 2, pressure, wind, and precipitation distribution over and University Rd., Pu-Tzu City, Chia-Yi County 61363, Taiwan. nearby Taiwan. The CMR is the principal range of E-mail: [email protected] mountains in Taiwan, and runs from the north to the DOI: 10.1175/WAF-D-14-00027.1 Ó 2014 American Meteorological Society Unauthenticated | Downloaded 10/05/21 02:09 PM UTC 1426 WEATHER AND FORECASTING VOLUME 29 FIG. 1. Location of the Penghu Islands and schematic diagram of the typhoon track classifications. south of Taiwan. The tallest peak of the CMR is Jade confining the storm to a cyclonic track around the Mountain (3952 m). The CMR is 340 km long and 80 km northern end of the CMR. Bender et al. (1985) observed wide, with an average height of 2500 m. As a typhoon that the mountain range affects the decay rate through approaches Taiwan, the topography of the CMR in- reduction in the supply of latent and kinetic energy into fluences its track and intensity (Wu and Kuo 1999; Tsai the storm circulation both during and after the passage and Lee 2009). The topography increases the rainfall of the storm over the mountain. Moreover, Hsu et al. amount significantly by lifting moist air over the wind- (2013) examined the effect of topographically phase- ward side of the mountains. The topography modulates locked convection with the CMR on the westward the wind field, and the rainfall pattern adjusts with the movement of typhoons across Taiwan. They deter- wind pattern (Wu et al. 2002). mined that topographically phase-locked convection acts A number of review studies on typhoons affecting to slow the northern landfalling typhoons and accelerate Taiwan have been investigated and have indicated that, the southern landfalling typhoons. These studies have when a typhoon approaches Taiwan, the CMR signifi- shown the substantial influences of the CMR topogra- cantly affects its circulation and track (Chang et al. phy on typhoons. 1993; Tsay 1994; Wu et al. 2002; Wu and Kuo 1999). Based on historical records, the Central Weather Brand and Blelloch (1974) found that westbound ty- Bureau (CWB) of Taiwan defined 10 typical track phoons tend to move cyclonically around the northern types based on typhoon statistics. For simplicity, the side of the CMR, and experience an average intensity typhoon tracks that affected the Penghu Islands are decrease of over 40%, starting approximately 12 h be- classified into the following six main track directions fore the storm centers reach the CMR. Wang (1980) (classes I–VI) (Fig. 1): direct westward movement documented and analyzed the path, intensity, propa- across the CMR of Taiwan (class I, comprising types gation speed, and evolution of 53 westbound typhoons 2–4); northward movement along the eastern coast of that approached Taiwan, indicating that the typhoon Taiwan (class II, comprising types 6 and 8); northward center was deflected toward the north as it approaches movement traveling through Taiwan Strait (class III, Taiwan, and toward the south after its passage over comprising types 7 and 9); westward movement traveling the CMR, because of the deflection of the mean through the Luzon Strait, which is the strait between steering flow upstream of the CMR. Using a primitive Taiwan and Luzon Island of the Philippines (class IV, equation model, Chang (1982) showed that, because comprising type 5); the direction of westward movement of blocking effects, mountain-induced flow deflections traveling through the southern East China Sea (near are mainly confined to the lower levels, and the passage northern Taiwan) (class V, comprising type 1); and the of the westward-approaching typhoon induces a mean irregular track direction except classes I–V (class VI, cyclonic circulation pattern around the mountain, comprising type 10). Unauthenticated | Downloaded 10/05/21 02:09 PM UTC DECEMBER 2014 W E I 1427 TABLE 1. Typhoons affecting the Penghu Islands during 2000–12 and typhoon information. Track Period affected Max wind in Max wind in class the Penghu Magong typhoon center Intensity 2 2 (type) Typhoon Islands (LST) (m s 1) (m s 1) category Class I Bilis 22–23 Aug 2000 15.9 53 Category 3 (types 2–4) Toraji 29–31 Jul 2001 9.3 38 Category 1 Lekima 26–28 Sep 2001 12.7 35 Category 1 Morakot 3–4 Aug 2003 6.7 23 Tropical storm Haitang 17–19 Jul 2005 16.8 55 Category 3 Talim 31 Aug–1 Sep 2005 17.0 53 Category 3 Longwang 1–3 Oct 2005 10.8 51 Category 3 Bilis 13–15 Jul 2006 12.9 25 Tropical storm Kaemi 24–26 Jul 2006 13.8 38 Category 1 Bopha 8–9 Aug 2006 8.0 23 Tropical storm Pabuk 7–9 Aug 2007 8.4 28 Tropical storm Sepat 17–19 Aug 2007 13.7 53 Category 3 Krosa 6–7 Oct 2007 12.6 51 Category 3 Kalmaegi 17–18 Jul 2008 8.9 33 Category 1 Fung-Wong 27–29 Jul 2008 15.9 43 Category 2 Sinlaku 12–14 Sep 2008 10.1 51 Category 3 Jangmi 27–29 Sep 2008 13.4 53 Category 3 Morakot 7–9 Aug 2009 15.4 40 Category 1 Fanapi 19–20 Sep 2010 18.9 45 Category 2 Nanmadol 28–31 Aug 2011 10.6 53 Category 3 Saola 31 Jul–3 Aug 2012 12.3 38 Category 1 Class II Kai-Tak 8–9 Jul 2000 8.2 35 Category 1 (types 6 and 8) Prapiroon 27–30 Aug 2000 7.1 33 Category 1 Xangsane 30 Oct–1 Nov 2000 12.0 38 Category 1 Cimaron 11–13 May 2001 9.9 23 Tropical storm Melor 2–3 Nov 2003 9.0 25 Tropical storm Mindulle 30 Jun–2 Jul 2004 9.0 45 Category 2 Haima 12–13 Sep 2004 5.6 18 Tropical storm Nock-Ten 24–25 Oct 2004 8.9 43 Category 2 Class III Chebi 22–24 Jun 2001 25.8 35 Category 1 (types 7 and 9) Nanmadol 3–4 Dec 2004 9.9 38 Category 1 Nakri 9–10 Jul 2002 11.9 18 Tropical storm Chanchu 17–18 May 2006 14.6 45 Category 2 Linfa 20–22 Jun 2009 14.8 28 Tropical storm Lionrock 31 Aug–2 Sep 2010 8.5 23 Tropical storm Megi 21–23
Load more

Recommended publications
  • Chapter 7. Building a Safe and Comfortable Society
    Section 1 Realizing a Universal Society Building a Safe and Comfortable Chapter 7 Society Section 1 Realizing a Universal Society 1 Realizing Accessibility through a Universal Design Concept The “Act on Promotion of Smooth Transportation, etc. of Elderly Persons, Disabled Persons, etc.” embodies the universal design concept of “freedom and convenience for anywhere and anyone”, making it mandatory to comply with “Accessibility Standards” when newly establishing various facilities (passenger facilities, various vehicles, roads, off- street parking facilities, city parks, buildings, etc.), mandatory best effort for existing facilities as well as defining a development target for the end of FY2020 under the “Basic Policy on Accessibility” to promote accessibility. Also, in accordance with the local accessibility plan created by municipalities, focused and integrated promotion of accessibility is carried out in priority development district; to increase “caring for accessibility”, by deepening the national public’s understanding and seek cooperation for the promotion of accessibility, “accessibility workshops” are hosted in which you learn to assist as well as virtually experience being elderly, disabled, etc.; these efforts serve to accelerate II accessibility measures (sustained development in stages). Chapter 7 (1) Accessibility of Public Transportation In accordance with the “Act on Figure II-7-1-1 Current Accessibility of Public Transportation Promotion of Smooth Transportation, etc. (as of March 31, 2014) of Elderly Persons, Disabled
    [Show full text]
  • 4. the TROPICS—HJ Diamond and CJ Schreck, Eds
    4. THE TROPICS—H. J. Diamond and C. J. Schreck, Eds. Pacific, South Indian, and Australian basins were a. Overview—H. J. Diamond and C. J. Schreck all particularly quiet, each having about half their The Tropics in 2017 were dominated by neutral median ACE. El Niño–Southern Oscillation (ENSO) condi- Three tropical cyclones (TCs) reached the Saffir– tions during most of the year, with the onset of Simpson scale category 5 intensity level—two in the La Niña conditions occurring during boreal autumn. North Atlantic and one in the western North Pacific Although the year began ENSO-neutral, it initially basins. This number was less than half of the eight featured cooler-than-average sea surface tempera- category 5 storms recorded in 2015 (Diamond and tures (SSTs) in the central and east-central equatorial Schreck 2016), and was one fewer than the four re- Pacific, along with lingering La Niña impacts in the corded in 2016 (Diamond and Schreck 2017). atmospheric circulation. These conditions followed The editors of this chapter would like to insert two the abrupt end of a weak and short-lived La Niña personal notes recognizing the passing of two giants during 2016, which lasted from the July–September in the field of tropical meteorology. season until late December. Charles J. Neumann passed away on 14 November Equatorial Pacific SST anomalies warmed con- 2017, at the age of 92. Upon graduation from MIT siderably during the first several months of 2017 in 1946, Charlie volunteered as a weather officer in and by late boreal spring and early summer, the the Navy’s first airborne typhoon reconnaissance anomalies were just shy of reaching El Niño thresh- unit in the Pacific.
    [Show full text]
  • Secessionist Activity Behind Solo Travel
    CHINA DAILY | HONG KONG EDITION Friday, August 2, 2019 | 3 TOP NEWS 7th Military Secessionist Games torch rally lauds activity behind PLA birth By ZHAO LEI solo travel ban [email protected] A torch relay for the upcoming 7th International Military Sports Individual permits to visit Taiwan Council Military World Games first allowed on trial basis in June 2011 began on Thursday in Nanchang, Jiangxi province. The flame was lit at a ceremony on By ZHANG YI “The launch of individual travel Thursday morning in front of a [email protected] permits in 2011 was a positive meas­ sculpture of Communist Party of ure to expand exchanges across the China revolutionaries inside the Ma Xiaoguang, spokesman for Straits in the climate of the peaceful The bed of Hongze Lake is exposed as water recedes due to the worst drought in decades in Nanchang August 1st Memorial Hall. the State Council’s Taiwan Affairs development of cross­Straits rela­ Huai’an, Jiangsu province, on Wednesday. PROVIDED TO CHINA DAILY Fang Minglu, the great­grand­ Office, said on Thursday that it is the tions,” Ma said. daughter of Fang Zhimin, a revolu­ island’s ruling Democratic Progres­ For years, mainland residents tionary martyr, lit the torch with a sive Party’s “Taiwan independence” visiting Taiwan played a positive concave mirror using the sun’s rays. secessionist activities that led to the role in promoting the development Business dries up for fishermen, Later, she passed the flame to a PLA suspension of individual travel per­ of Taiwan's tourism and related soldier who transferred it to a carrier.
    [Show full text]
  • Flood Hazard Mapping in an Urban Area Using Combined Hydrologic-Hydraulic Models and Geospatial Technologies
    Global J. Environ. Sci. Manage. 5(2): 139-154, Spring 2019 Global Journal of Environmental Science and Management (GJESM) Homepage: https://www.gjesm.net/ ORIGINAL RESEARCH PAPER Flood hazard mapping in an urban area using combined hydrologic-hydraulic models and geospatial technologies B.A.M.Talisay*, G.R. Puno, R.A.L. Amper GeoSAFER Northern Mindanao/ Cotabato Project, College of Forestry and Environmental Science, Central Mindanao University, Musuan, Maramag, Bukidnon, Philippines ARTICLE INFO ABSTRACT Flooding is one of the most occurring natural hazards every year risking the lives and Article History: Received 12 August 2018 properties of the affected communities, especially in Philippine context. To visualize Revised 12 November 2018 the extent and mitigate the impacts of flood hazard in Malingon River in Valencia Accepted 30 November 2018 City, Bukidnon, this paper presents the combination of Geographic Information System, high-resolution Digital Elevation Model, land cover, soil, observed hydro-meteorological data; and the combined Hydrologic Engineering Center- Keywords: Hydrologic Modeling System and River Analysis System models. The hydrologic Geographic information system (GIS) model determines the precipitation-runoff relationships of the watershed and the Inundation hydraulic model calculates the flood depth and flow pattern in the floodplain area. Light detection and ranging The overall performance of hydrologic model during calibration was “very good fit” Model calibration based on the criterion of Nash-Sutcliffe Coefficient of Model Efficiency, Percentage Bias and Root Mean Square Error – Observations Standard Deviation Ratio with the values of 0.87, -8.62 and 0.46, respectively. On the other hand, the performance of hydraulic model during error computation was “intermediate fit” using F measure analysis with a value of 0.56, using confusion matrix with 80.5% accuracy and the Root Mean Square Error of 0.47 meters.
    [Show full text]
  • Sigma 1/2008
    sigma No 1/2008 Natural catastrophes and man-made disasters in 2007: high losses in Europe 3 Summary 5 Overview of catastrophes in 2007 9 Increasing flood losses 16 Indices for the transfer of insurance risks 20 Tables for reporting year 2007 40 Tables on the major losses 1970–2007 42 Terms and selection criteria Published by: Swiss Reinsurance Company Economic Research & Consulting P.O. Box 8022 Zurich Switzerland Telephone +41 43 285 2551 Fax +41 43 285 4749 E-mail: [email protected] New York Office: 55 East 52nd Street 40th Floor New York, NY 10055 Telephone +1 212 317 5135 Fax +1 212 317 5455 The editorial deadline for this study was 22 January 2008. Hong Kong Office: 18 Harbour Road, Wanchai sigma is available in German (original lan- Central Plaza, 61st Floor guage), English, French, Italian, Spanish, Hong Kong, SAR Chinese and Japanese. Telephone +852 2582 5691 sigma is available on Swiss Re’s website: Fax +852 2511 6603 www.swissre.com/sigma Authors: The internet version may contain slightly Rudolf Enz updated information. Telephone +41 43 285 2239 Translations: Kurt Karl (Chapter on indices) CLS Communication Telephone +41 212 317 5564 Graphic design and production: Jens Mehlhorn (Chapter on floods) Swiss Re Logistics/Media Production Telephone +41 43 285 4304 © 2008 Susanna Schwarz Swiss Reinsurance Company Telephone +41 43 285 5406 All rights reserved. sigma co-editor: The entire content of this sigma edition is Brian Rogers subject to copyright with all rights reserved. Telephone +41 43 285 2733 The information may be used for private or internal purposes, provided that any Managing editor: copyright or other proprietary notices are Thomas Hess, Head of Economic Research not removed.
    [Show full text]
  • October 2013 Global Catastrophe Recap 2 2
    October 2013 Global Catastrophe Recap Table of Contents Executive0B Summary 3 United2B States 4 Remainder of North America (Canada, Mexico, Caribbean, Bermuda) 4 South4B America 4 Europe 4 6BAfrica 5 Asia 5 Oceania8B (Australia, New Zealand and the South Pacific Islands) 6 8BAAppendix 7 Contact Information 14 Impact Forecasting | October 2013 Global Catastrophe Recap 2 2 Executive0B Summary . Windstorm Christian affects western and northern Europe; insured losses expected to top USD1.35 billion . Cyclone Phailin and Typhoon Fitow highlight busy month of tropical cyclone activity in Asia . Deadly bushfires destroy hundreds of homes in Australia’s New South Wales Windstorm Christian moved across western and northern Europe, bringing hurricane-force wind gusts and torrential rains to several countries. At least 18 people were killed and dozens more were injured. The heaviest damage was sustained in the United Kingdom, France, Belgium, the Netherlands and Scandinavia, where a peak wind gust of 195 kph (120 mph) was recorded in Denmark. More than 1.2 million power outages were recorded and travel was severely disrupted throughout the continent. Reports from European insurers suggest that payouts are likely to breach EUR1.0 billion (USD1.35 billion). Total economic losses will be even higher. Christian becomes the costliest European windstorm since WS Xynthia in 2010. Cyclone Phailin became the strongest system to make landfall in India since 1999, coming ashore in the eastern state of Odisha. At least 46 people were killed. Tremendous rains, an estimated 3.5-meter (11.0-foot) storm surge, and powerful winds led to catastrophic damage to more than 430,000 homes and 668,000 hectares (1.65 million) acres of cropland.
    [Show full text]
  • (OSCAT) and ASCAT Scatterometers Over Tropical Cyclones Goal of Study
    P1.37P197 Comparisons and Evaluations between the Oceansat-2 (OSCAT) and ASCAT Scatterometers over Tropical Cyclones Roger T. Edson, NOAA National Weather Service, Barrigada Guam Coverage and Availability of Scatterometer: OSCAT vs. ASCAT and WindSAT Case Studies of Different Tropical Cyclone Characteristics or OSCAT (~2400L) Goal of Study NOAA/NESDIS –’Manati Site’ KNMI – EUMETSAT site Typhoon Man-Yi (16W) development from a ASCAT depiction of the development and OSCAT View monsoon gyre north or the Marianas -Compare reliability, depiction and BYU Hi-Res OSCAT intensification of Typhoon Mawar (04W) accuracy over tropical cyclones -Find strengths and weaknesses -Assess comparative loss with QuikSCAT -Evaluate NRCS and BYU Hi-Res IR and OSCAT Winds TRMM 85h with OSCAT NRCS OSCAT Development was slow with a large light and variable wind center. At this products to assist analysis time winds were beginning to consolidate about one circulation center as Combine ASCAT A/B with either OSCAT better seen in the OSCAT NRCS and BYU Hi-Res images. or WindSAT to increase coverage -Use of integrated techniques, Sensor Characteristics especially with microwave Sensor/Sat QuikSCAT ASCAT A/B WindSAT OSCAT-2 48hr Structure and intensity between 31 May (25kt) and 2 Jun (70kt) TYPE Active Active Passive Active imagery AGENCY/re-Processed JPL/NESDIS ESA/KNMI US Navy India/KNMI LAUNCH/END 1999/Nov09(end) 2006/12 2003 2009 Typhoon Tembin (15W) approaching Japan SWATH (KM) 1800 2 X 550 ~1100 1836 The intensity of a tropical cyclone that has begun GAP (KM) 0 600 N/A N/A extra-tropical transition is often underestimated RESOLUTION (KM) 25 (12.5) 50 (25) 25 50 (25) Goal of Scatterometer Data for TC Analysis when intensity is solely based on the Dvorak SPEED (KT) 4-80 5-60 10-40 5-60? Technique.
    [Show full text]
  • Research Article Application of Buoy Observations in Determining Characteristics of Several Typhoons Passing the East China Sea in August 2012
    Hindawi Publishing Corporation Advances in Meteorology Volume 2013, Article ID 357497, 6 pages http://dx.doi.org/10.1155/2013/357497 Research Article Application of Buoy Observations in Determining Characteristics of Several Typhoons Passing the East China Sea in August 2012 Ningli Huang,1 Zheqing Fang,2 and Fei Liu1 1 Shanghai Marine Meteorological Center, Shanghai, China 2 Department of Atmospheric Science, Nanjing University, Nanjing, China Correspondence should be addressed to Zheqing Fang; [email protected] Received 27 February 2013; Revised 5 May 2013; Accepted 21 May 2013 Academic Editor: Lian Xie Copyright © 2013 Ningli Huang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The buoy observation network in the East China Sea is used to assist the determination of the characteristics of tropical cyclone structure in August 2012. When super typhoon “Haikui” made landfall in northern Zhejiang province, it passed over three buoys, the East China Sea Buoy, the Sea Reef Buoy, and the Channel Buoy, which were located within the radii of the 13.9 m/s winds, 24.5 m/s winds, and 24.5 m/s winds, respectively. These buoy observations verified the accuracy of typhoon intensity determined by China Meteorological Administration (CMA). The East China Sea Buoy had closely observed typhoons “Bolaven” and “Tembin,” which provided real-time guidance for forecasters to better understand the typhoon structure and were also used to quantify the air-sea interface heat exchange during the passage of the storm.
    [Show full text]
  • 二零一七熱帶氣旋tropical Cyclones in 2017
    176 第四節 熱帶氣旋統計表 表4.1是二零一七年在北太平洋西部及南海區域（即由赤道至北緯45度、東 經 100度至180 度所包括的範圍）的熱帶氣旋一覽。表內所列出的日期只說明某熱帶氣旋在上述範圍內 出現的時間，因而不一定包括整個風暴過程。這個限制對表內其他元素亦同樣適用。 表4.2是天文台在二零一七年為船舶發出的熱帶氣旋警告的次數、時段、首個及末個警告 發出的時間。當有熱帶氣旋位於香港責任範圍內時（即由北緯10至30度、東經105至125 度所包括的範圍），天文台會發出這些警告。表內使用的時間為協調世界時。 表4.3是二零一七年熱帶氣旋警告信號發出的次數及其時段的摘要。表內亦提供每次熱帶 氣旋警告信號生效的時間和發出警報的次數。表內使用的時間為香港時間。 表4.4是一九五六至二零一七年間熱帶氣旋警告信號發出的次數及其時段的摘要。 表4.5是一九五六至二零一七年間每年位於香港責任範圍內以及每年引致天文台需要發 出熱帶氣旋警告信號的熱帶氣旋總數。 表4.6是一九五六至二零一七年間天文台發出各種熱帶氣旋警告信號的最長、最短及平均 時段。 表4.7是二零一七年當熱帶氣旋影響香港時本港的氣象觀測摘要。資料包括熱帶氣旋最接 近香港時的位置及時間和當時估計熱帶氣旋中心附近的最低氣壓、京士柏、香港國際機 場及橫瀾島錄得的最高風速、香港天文台錄得的最低平均海平面氣壓以及香港各潮汐測 量站錄得的最大風暴潮（即實際水位高出潮汐表中預計的部分，單位為米）。 表4.8.1是二零一七年位於香港600公里範圍內的熱帶氣旋及其為香港所帶來的雨量。 表4.8.2是一八八四至一九三九年以及一九四七至二零一七年十個為香港帶來最多雨量 的熱帶氣旋和有關的雨量資料。 表4.9是自一九四六年至二零一七年間，天文台發出十號颶風信號時所錄得的氣象資料， 包括熱帶氣旋吹襲香港時的最近距離及方位、天文台錄得的最低平均海平面氣壓、香港 各站錄得的最高60分鐘平均風速和最高陣風。 表4.10是二零一七年熱帶氣旋在香港所造成的損失。資料參考了各政府部門和公共事業 機構所提供的報告及本地報章的報導。 表4.11是一九六零至二零一七年間熱帶氣旋在香港所造成的人命傷亡及破壞。資料參考 了各政府部門和公共事業機構所提供的報告及本地報章的報導。 表4.12是二零一七年天文台發出的熱帶氣旋路徑預測驗証。 177 Section 4 TROPICAL CYCLONE STATISTICS AND TABLES TABLE 4.1 is a list of tropical cyclones in 2017 in the western North Pacific and the South China Sea (i.e. the area bounded by the Equator, 45°N, 100°E and 180°). The dates cited are the residence times of each tropical cyclone within the above‐mentioned region and as such might not cover the full life‐ span. This limitation applies to all other elements in the table. TABLE 4.2 gives the number of tropical cyclone warnings for shipping issued by the Hong Kong Observatory in 2017, the durations of these warnings and the times of issue of the first and last warnings for all tropical cyclones in Hong Kong's area of responsibility (i.e. the area bounded by 10°N, 30°N, 105°E and 125°E). Times are given in hours and minutes in UTC. TABLE 4.3 presents a summary of the occasions/durations of the issuing of tropical cyclone warning signals in 2017. The sequence of the signals displayed and the number of tropical cyclone warning bulletins issued for each tropical cyclone are also given.
    [Show full text]
  • Abstract Proceeding
    1 The Proceedings for The 6th International Conference on Atmosphere, Ocean, and Climate Change August 19 - 21, 2013, Hong Kong Editors: Dr. Banghua Yan Dr. Xiaozhen Xiong Prof. Zhanqing Li Dr. Jingfeng Huang 2 EFFECTS OF AIR-SEA COUPLING ON THE BOREAL SUMMER INTRASEASONAL OSCILLATIONS OVER THE TROPICAL INDIAN OCEAN Ailan Lin1,2, Tim Li, Xiouhua Fu2, Jing-Jia Luo3, Yukio Masumoto3 1 Institute of Tropical and Marine Meteorology, China Meteorological Administration, Guangzhou, China 2. IPRC and Department of Meteorology, University of Hawaii, Honolulu, Hawaii 3. Research Institute for Global Change, JAMSTEC, Yokohama, Japan Abstract The effects of air-sea coupling over the tropical Indian Ocean (TIO) on the eastward- and northward-propagating boreal summer intraseasonal oscillation (BSISO) are investigated by comparing a fully coupled (CTL) and a partially decoupled Indian Ocean (pdIO) experiment using SINTEX-F coupled GCM. Air-sea coupling over the TIO significantly enhances the intensity of both the eastward and northward propagations of the BSISO. The maximum spectrum differences of the northward- (eastward-) propagating BSISO between the CTL and pdIO reach 30% (25%) of their respective climatological values. The enhanced eastward (northward) propagation is related to the zonal (meridional) asymmetry of sea surface temperature anomaly (SSTA). A positive SSTA appears to the east (north) of the BSISO convection, which may positively feed back to the BSISO convection. In addition, air-sea coupling may enhance the northward propagation through the changes of the mean vertical wind shear and low-level specific humidity. The interannual variations of the TIO regulate the air-sea interaction effect. Air-sea coupling enhances (reduces) the eastward-propagating spectrum during the negative Indian Ocean dipole (IOD) mode, positive Indian Ocean basin (IOB) mode and normal years (during positive IOD and negative IOB years).
    [Show full text]
  • Met Office Unified Model Tropical Cyclone Performance Following Major Changes to the Initialization Scheme and a Model Upgrade
    OCTOBER 2016 H E M I N G 1433 Met Office Unified Model Tropical Cyclone Performance Following Major Changes to the Initialization Scheme and a Model Upgrade JULIAN T. HEMING Met Office, Exeter, Devon, United Kingdom (Manuscript received 1 March 2016, in final form 27 June 2016) ABSTRACT The Met Office has used various schemes to initialize tropical cyclones (TCs) in its numerical weather pre- diction models since the 1980s. The scheme introduced in 1994 was particularly successful in reducing track forecast errors in the model. Following modifications in 2007 the scheme was still beneficial, although to a lesser degree than before. In 2012 a new trial was conducted that showed that the scheme now had a detrimental impact on TC track forecasts. As a consequence of this, the scheme was switched off. The Met Office Unified Model (MetUM) underwent a major upgrade in 2014 including a new dynamical core, changes to the model physics, an increase in horizontal resolution, and changes to satellite data usage. An evaluation of the impact of this change on TC forecasts found a positive impact both on track and particularly intensity forecasts. Following implementation of the new model formulation in 2014, a new scheme for initialization of TCs in the MetUM was developed that involved the assimilation of central pressure estimates from TC warning centers. A trial showed that this had a positive impact on both track and intensity predictions from the model. Operational results from the MetUM in 2014 and 2015 showed that the combined impact of the model upgrade and new TC initialization scheme was a dramatic cut in both TC track forecast errors and intensity forecast bias.
    [Show full text]
  • Pdf | 431.12 Kb
    ASIA PACIFIC REGION 22 - 28 October, 2013 Weekly Regional Humanitarian Snapshot from the OCHA Regional Office in Asia and the Pacific 1 PHILIPPINES Probability of Above/Below As of 21 Oct, the 7.2M earthquake in Bohol had killed 186 people, affected some 3 Normal Precipitation r" million, and left nearly 381,000 people displaced of whom 70% or 271,000 were staying (Nov 2013 - Jan 2014) outside of established evacuation centers. These people were in urgent need of shelter Above normal rainfall and WASH support. Psycho-social support was identified as an urgent need for children traumatized by the earthquake, which has produced well over 2,000 aftershocks so far. Recently repaired bridges and roads have opened greater access to affected locations M O N G O L I A normal in Bohol. The Government has welcomed international assistance. Source: OCHA Sitrep No. 4 DPR KOREA Below normal rainfall 2 CAMBODIA 5 Floods across Cambodia have claimed 168 lives, displaced almost 145,000 and 5 RO KOREA JAPAN r" p" u" affected more than 1.7 million. Waters have begun to recede across the country with the worst affected provinces being Battambang and Banteay Meanchey, where many parts C H I N A LEKIMA KOBE remain flooded. Communities are in urgent need of clean water, basic sanitation and BHUTAN emergency shelter. NEPAL p" 5 Source: HRF Sitrep No. 4 KATHMANDU 3 INDIA PA C I F I C Heavy rainfall has been affecting the states of Andhra Pradesh and Odisha, SE India, in BANGLADESH FRANCISCO I N D I A u" the last few days.
    [Show full text]