DOCSLIB.ORG

Intensification and Structure Change of Super Typhoon Flo As Related to the Large-Scale Environment

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Intensification and Structure Change of Super Typhoon Flo As Related to the Large-Scale Environment N PS ARCHIVE 1998.06 TITLEY, D. NAVAL POSTGRADUATE SCHOOL Monterey, California DISSERTATION INTENSIFICATION AND STRUCTURE CHANGE OF SUPER TYPHOON FLO AS RELATED TO THE LARGE-SCALE ENVIRONMENT by David W. Titley June 1998 Dissertation Supervisor: Russell L. Elsberry Thesis T5565 Approved for public release; distribution is unlimited. -EYKNC . •OOL DUDLEY KNOX LIBRARY NAVAL POSTGRADUATE SCHOOL MONTEREY, CA 93943-5101 REPORT DOCUMENTATION PAGE Form Approved OMB No 0704-01! Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instruction, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of ManagemerJ and Budget, Paperwork Reduction Project (0704-0188) Washington DC 20503. 1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED June 1998. Doctoral Dissertation 4. TITLE AND SUBTITLE Intensification and Structure Change of Super 5. FUNDING NUMBERS Typhoon Flo as Related to the Large-Scale Environment 6. AUTHOR(S) Titley, David W. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) PERFORMING Naval Postgraduate School ORGANIZATION Monterey CA 93943-5000 REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING AGENCY REPORT NUMBER 11. SUPPLEMENTARY NOTES The views expressed in this thesis are those of the author and do not reflect the official policy or position of the Department of Defense or the U.S. Government. 12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE Approved for public release; distribution is unlimited. 13. ABSTRACT (maximum 200 words) A Multi-Quadric (MQ) analysis is developed and compared with the four-dimensional data assimilation analyses of the structure of Typhoons Flo and Ed during the Tropical Cyclone Motion (TCM-90) field experiment. The MQ analysis has been shown to provide an alternate, plausible depiction of the tropical atmosphere. These analyses are used to compare physical processes leading to rapid intensification of Flo, but not of Ed. Significant documentations include: (i) the existence of a "cyclonic wind burst" extending beyond 1000 km radius at 200 mb during the forcing phase for Typhoon Flo, which appears to be the result of strong, sustained eddy flux convergence of angular momentum (EFC) in the upper troposphere; (ii) a complex EFC vertical structure that evolved with time; (iii) Flo had developed a warmer core near the tropopause, and was less stable than Ed in the upper troposphere prior to the beginning of the rapid intensification period; (iv) a high correlation of the mid-troposphere azimuthally-averaged absolute vorticity with the 48-h future intensity of four tropical cyclones; and (v) the 850 - 200 mb vertical wind shear for Typhoon Ed was less than the vertical shear calculated for Typhoon Flo, which implies that low vertical shear, although necessary for significant storm development is not, by itself, a sufficient dynamic factor to ensure rapid intensification. A conceptual model is proposed for tropical cyclone rapid intensification and subsequent weakening that accounts for varying EFC and vertical shear values. Although based on Typhoons Ed and Flo, this model is also consistent with intensity changes of Typhoons Yancy and Zola. 14. SUBJECT TERMS Tropical Cyclone Intensification, Objective Analysis Method, 15. NUMBER OF Multi-Quadric Analysis. PAGES 389 16. PRICE CODE 17. SECURITY CLASSIFI- SECURITY CLASSIFI- 19. SECURITY CLASSIFI- 20. LIMITATION OF CATION OF REPORT CATION OF THIS PAGE CATION OF ABSTRACT ABSTRACT Unclassified Unclassified Unclassified UL NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89) Prescribed by ANSI Std. 239-18 298-102 11 DUDLEY KNOX LIBRARY NAVAL POSTGRADUATE SCHOOL Approved for public release; distribution is unlinMeWEREY> CA 93943-5101 INTENSIFICATION AND STRUCTURE CHANGE OF SUPER TYPHOON FLO AS RELATED TO THE LARGE-SCALE ENVIRONMENT David W. Titley Commander, United States Navy B.S., The Pennsylvania State University, 1980 M.S.,Naval Postgraduate School, 1991 Submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY IN METEOROLOGY from the NAVAL POSTGRADUATE SCHOOL June 1998 DUDLEY KNOX LIBRARY NAV. 00 , ABSTRACT A Multi-Quadric (MQ) analysis is developed and compared with the four-dimensional data assimilation analyses of the structure of Typhoons Flo and Ed during the Tropical Cyclone Motion (TCM-90) field experiment. The MQ analysis has been shown to provide an alternate, plausible depiction of the tropical atmosphere. These analyses are used to compare physical processes leading to rapid intensification of Flo, but not of Ed. Significant documentations include: (i) the existence of a "cyclonic wind burst" extending beyond 1000 km radius at 200 mb during the forcing phase for Typhoon Flo, which appears to be the result of strong, sustained eddy flux convergence of angular momentum (EFC) in the upper troposphere; (ii) a complex EFC vertical structure that evolved with time; (iii) Flo had developed a warmer core near the tropopause, and was less stable than Ed in the upper troposphere prior to the beginning of the rapid intensification period; (iv) a high correlation of the mid-troposphere azimuthally-averaged absolute vorticity with the 48-h future intensity of four tropical cyclones; and (v) the 850 - 200 mb vertical wind shear for Typhoon Ed was less than the vertical shear calculated for Typhoon Flo, which implies that low vertical shear, although necessary for significant storm development is not, by itself, a sufficient dynamic factor to ensure rapid intensification. A conceptual model is proposed for tropical cyclone rapid intensification and subsequent weakening that accounts for varying EFC and vertical shear values. Although based on Typhoons Ed and Flo, this model is also consistent with intensity changes of Typhoons Yancy and Zola. VI TABLE OF CONTENTS I. INTRODUCTION 1 A. MOTIVATION 1 B. PREVIOUS WORK ON TROPICAL CYCLONE INTENSITY .... 4 1. Thermodynamic Considerations 6 2. Mid-latitude and Tropical Upper Tropospheric Trough (TUTT) Interactions with Tropical Cyclones 12 3. Vertical Wind Shear 21 4. Identification of Common Predictors for Tropical Cyclone Intensification 23 C. GOALS AND HYPOTHESES 24 D. APPROACH 26 II. DATA ANALYSIS 29 A. TROPICAL CYCLONE MOTION FIELD EXPERIMENT 29 B. GRIDDED ANALYSES 34 C. ANALYSIS METHOD 34 1. Background 34 2. Method Chosen 36 a. Multi-Quadric Method 37 (1) Smoothing 39 vn (2) Dynamic Constraints 44 b. Application of the Multi-Quadric Method 45 (1) Increment Analysis 45 (2) Horizontal Resolution 52 (3) Vertical Resolution 52 (4) Analysis Domain 52 (5) Analyzed Parameters 54 3. Summary 54 D. DATA MANAGEMENT 55 1. Data Preparation 57 2. Quality Control 57 E. LOCAL OBJECTIVE ANALYSIS SCHEME 58 1 . Observation Quality Control 60 a. Horizontal Quality Control Checks 60 b. Radiation Error Corrections 68 c. DC-8 and LORAN Dropwindsonde Height Observations 72 (1) Adjusting the heights to the nearest mandatory pressure level 72 (2) DC-8 and LORAN Dropwindsonde Height Bias. 73 Vlll 2. Dynamic Constraints 76 3. First-Guess Modifications 81 4. Observation Enhancements 90 a. Composite Observations 90 b. Synthetic Observations 91 (1) Zero-bogus Observations 91 (2) Typhoon Depiction Observations 95 5. Post-processing the Tropical Cyclone Wind Field 98 6. 0600 and 1800 UTC Analyses 99 7. Summary 99 VORTICITY, DIVERGENCE, AND VERTICAL VELOCITY CALCULATIONS 101 1. Vorticity 101 2. Divergence 102 3. Vertical Motion 102 a. Computing the Surface Pressure 103 1 1 b. Converting vertical velocity from /^bar s" to m s" . 105 4. Summary 105 IX III. INITIAL VALIDATION OF THE MULTI-QUADRIC ANALYSES .... 107 A. VALIDATION AND COMPARISON OF THE MULTI-QUADRIC ANALYSES 107 1. Qualitative Checks 108 a. Two-Dimensional Plots 108 b. Comparison With Rucker Hand Analyses 110 c. Dataset Visualization 116 2. Quantitative Checks 121 a. Root Mean Square Evaluation 121 (1) Wind RMS Calculations 123 (2) Height RMS Calculations 135 (3) RMS Summary 138 b. Propagation Vector Analysis 140 (1) Introduction 140 (2) Typhoon Flo Storm Motion, Large-Scale Steering Flow, and Propagation Vectors 143 c. Azimuthally-Averaged Winds in the Vicinity of Typhoon Flo 148 (1) 850 mb Tangential Wind Speed 149 (2) 200 mb Tangential Wind Speed 155 (3) Vertical Cross-Sections of Tangential Wind Speed 161 (4) 850 mb Radial Wind Speed 163 (5) 200 mb Radial Wind Speed 168 (6) Vertical Cross-Sections of Radial Wind Speed. 172 (7) Summary 174 B. ANALYSIS CONCLUSIONS 177 C. FUTURE ANALYSIS WORK 179 1. Multi-Quadric Analysis Enhancements 179 2. Data Impact and Sensitivity Studies 180 IV. DISCUSSION OF DYNAMICS OF TYPHOONS ED AND FLO 183 A. STRENGTHS AND LIMITATIONS OF THE ANALYSES .... 183 B. EFFECT OF THERMAL INFLUENCES ON TYPHOONS ED AND FLO 184 1. Sea-Surface Temperature 184 2. Thermal Structure of Ed and Flo 186 a. Background 186 b. Analysis Method 187 c. Results 189 XI TIME EVOLUTION OF UPPER-TROPOSPHERIC WINDS IN TYPHOONS ED AND FLO 190 1. Motivation 190 2. Analysis Method 191 a. Tangential and Radial Wind Calculations 191 b. Vertical Wind Shear Calculations 193 3. Typhoon Flo 193 a. Forcing Phase (00 UTC 13 September to 12 UTC 14 September) 194 (1) Tangential Wind 196 (2) Radial Wind 200 (3) Eddy Flux Convergence of Relative Angular Momentum 212 (4) Vertical Wind Shear 218 (5) Discussion and Conclusions 221 b. Quiescent Forcing Phase (18 UTC 14 September through 12 UTC 16 September) 225 (1) Contraction Phase 225 (2) Rapid Intensification Phase 234 c. Super Typhoon Phase (12 UTC 16 September through 18 UTC 17 September) 249 xn . d . Mid-latitude Interaction Phase (00 UTC 1 8 September to 00 UTC 19 September) 263 4.
Load more

Recommended publications
  • Typhoon Neoguri Disaster Risk Reduction Situation Report1 DRR Sitrep 2014‐001 ‐ Updated July 8, 2014, 10:00 CET
    Typhoon Neoguri Disaster Risk Reduction Situation Report1 DRR sitrep 2014‐001 ‐ updated July 8, 2014, 10:00 CET Summary Report Ongoing typhoon situation The storm had lost strength early Tuesday July 8, going from the equivalent of a Category 5 hurricane to a Category 3 on the Saffir‐Simpson Hurricane Wind Scale, which means devastating damage is expected to occur, with major damage to well‐built framed homes, snapped or uprooted trees and power outages. It is approaching Okinawa, Japan, and is moving northwest towards South Korea and the Philippines, bringing strong winds, flooding rainfall and inundating storm surge. Typhoon Neoguri is a once‐in‐a‐decade storm and Japanese authorities have extended their highest storm alert to Okinawa's main island. The Global Assessment Report (GAR) 2013 ranked Japan as first among countries in the world for both annual and maximum potential losses due to cyclones. It is calculated that Japan loses on average up to $45.9 Billion due to cyclonic winds every year and that it can lose a probable maximum loss of $547 Billion.2 What are the most devastating cyclones to hit Okinawa in recent memory? There have been 12 damaging cyclones to hit Okinawa since 1945. Sustaining winds of 81.6 knots (151 kph), Typhoon “Winnie” caused damages of $5.8 million in August 1997. Typhoon "Bart", which hit Okinawa in October 1999 caused damages of $5.7 million. It sustained winds of 126 knots (233 kph). The most damaging cyclone to hit Japan was Super Typhoon Nida (reaching a peak intensity of 260 kph), which struck Japan in 2004 killing 287 affecting 329,556 people injuring 1,483, and causing damages amounting to $15 Billion.
    [Show full text]
  • 1 Storm Surge in Seto Inland Sea with Consideration Of
    STORM SURGE IN SETO INLAND SEA WITH CONSIDERATION OF THE IMPACTS OF WAVE BREAKING ON SURFACE CURRENTS Han Soo Lee1, Takao Yamashita1, Tomoaki Komaguchi2, and Toyoaki Mishima3 Storm surge and storm wave simulations in Seto Inland Sea (SIS) in Japan were conducted for Typhoon Yancy (9313) and Chaba (0416) using an atmosphere (MM5)-wave (SWAN)-ocean (POM) modeling system. In the coupled modeling system, a new method for wave-current interaction in terms of momentum transfer due to whitecapping in deep water and depth-induced wave breaking in shallow water was considered. The calculated meteorological and wave fields show good agreement with the observations in SIS and its vicinities. The storm surge results also exhibit good accordance with the observations in SIS. To resolve a number of islands in SIS, we also performed numerical experiments with different grid resolutions and obtained improved results from higher resolutions in wave and ocean circulation fields. Keywords: Seto Inland Sea; storm surge; atmosphere-wave-ocean coupled model; air-sea interaction; whitecapping; depth-induced wave breaking INTRODUCTION Storm surge due to tropical cyclones (TCs) varies from place to place depending on the geographical features of the place we are interested in such as the effect of surrounding topography on meteorological fields, geographical shape of the bay or harbor, underwater bathymetry, tide, and interaction with other water bodies including rivers and open seas and oceans. In the storm surge modeling it is difficult to consider all of these effects such that we have to compromise some of them for simplifying a problem, more efficient modeling and engineering purpose.
    [Show full text]
  • Toward the Establishment of a Disaster Conscious Society
    Special Feature Consecutive Disasters --Toward the Establishment of a Disaster Conscious Society-- In 2018, many disasters occurred consecutively in various parts of Japan, including earthquakes, heavy rains, and typhoons. In particular, the earthquake that hit the northern part of Osaka Prefecture on June 18, the Heavy Rain Event of July 2018 centered on West Japan starting June 28, Typhoons Jebi (1821) and Trami (1824), and the earthquake that stroke the eastern Iburi region, Hokkaido Prefecture on September 6 caused damage to a wide area throughout Japan. The damage from the disaster was further extended due to other disaster that occurred subsequently in the same areas. The consecutive occurrence of major disasters highlighted the importance of disaster prevention, disaster mitigation, and building national resilience, which will lead to preparing for natural disasters and protecting people’s lives and assets. In order to continue to maintain and improve Japan’s DRR measures into the future, it is necessary to build a "disaster conscious society" where each member of society has an awareness and a sense of responsibility for protecting their own life. The “Special Feature” of the Reiwa Era’s first White Paper on Disaster Management covers major disasters that occurred during the last year of the Heisei era. Chapter 1, Section 1 gives an overview of those that caused especially extensive damage among a series of major disasters that occurred in 2018, while also looking back at response measures taken by the government. Chapter 1, Section 2 and Chapter 2 discuss the outline of disaster prevention and mitigation measures and national resilience initiatives that the government as a whole will promote over the next years based on the lessons learned from the major disasters in 2018.
    [Show full text]
  • Field Surveys and Numerical Simulation of the 2018 Typhoon Jebi: Impact of High Waves and Storm Surge in Semi-Enclosed Osaka Bay, Japan
    Pure Appl. Geophys. 176 (2019), 4139–4160 Ó 2019 Springer Nature Switzerland AG https://doi.org/10.1007/s00024-019-02295-0 Pure and Applied Geophysics Field Surveys and Numerical Simulation of the 2018 Typhoon Jebi: Impact of High Waves and Storm Surge in Semi-enclosed Osaka Bay, Japan 1 1 2 1 1 TUAN ANH LE, HIROSHI TAKAGI, MOHAMMAD HEIDARZADEH, YOSHIHUMI TAKATA, and ATSUHEI TAKAHASHI Abstract—Typhoon Jebi made landfall in Japan in 2018 and hit 1. Introduction Osaka Bay on September 4, causing severe damage to Kansai area, Japan’s second largest economical region. We conducted field surveys around the Osaka Bay including the cities of Osaka, Annually, an average of 2.9 tropical cyclones Wakayama, Tokushima, Hyogo, and the island of Awaji-shima to (from 1951 to 2016) have hit Japan (Takagi and evaluate the situation of these areas immediately after Typhoon Esteban 2016; Takagi et al. 2017). The recent Jebi struck. Jebi generated high waves over large areas in these regions, and many coasts were substantially damaged by the Typhoon Jebi in September 2018 has been the combined impact of high waves and storm surges. The Jebi storm strongest tropical cyclone to come ashore in the last surge was the highest in the recorded history of Osaka. We used a 25 years since Typhoon Yancy (the 13th typhoon to storm surge–wave coupled model to investigate the impact caused by Jebi. The simulated surge level was validated with real data hit Japan, in 1993), severely damaging areas in its acquired from three tidal stations, while the wave simulation results trajectory.
    [Show full text]
  • U Ncorrected Proof
    Pure Appl. Geophys. Ó 2019 Springer Nature Switzerland AG https://doi.org/10.1007/s00024-019-02295-0 Pure and Applied Geophysics 1 Field Surveys and Numerical Simulation of the 2018 Typhoon Jebi: Impact of High Waves 2 and Storm Surge in Semi-enclosed Osaka Bay, Japan 3 1 1 2 1 1 4 LE TUAN ANH, HIROSHI TAKAGI, MOHAMMAD HEIDARZADEH, YOSHIHUMI TAKATA, and ATSUHEI TAKAHASHI 5 Abstract—Typhoon Jebi made landfall in Japan in 2018 and hit 1. Introduction 39 6 Osaka Bay on September 4, causing severe damage to Kansai area, 7 Japan’s second largest economical region. We conducted field 8 surveys around the Osaka Bay including the cities of Osaka, Annually, an average of 2.9 tropical cyclones 40 Author Proof 9 Wakayama, Tokushima, Hyogo, and the island of Awaji-shima to (from 1951 to 2016) have hit Japan (Takagi and 41 10 evaluate the situation of these areas immediately after Typhoon 42 11 Esteban 2016; Takagi et al. 2017). The recent Jebi struck. Jebi generated high waves over large areas in these 43 12 regions, and many coasts were substantially damaged by the Typhoon Jebi in September 2018 has been the 13 combined impact of high waves and storm surges. The Jebi storm strongest tropical cyclone to come ashore in the last 44 14 surge was the highest in the recorded history of Osaka. We used a 45 15 25 years since Typhoon Yancy (the 13th typhoon to storm surge–wave coupled model to investigate the impact caused 46 16 by Jebi. The simulated surge level was validated with real data hit Japan, in 1993), severely damaging areas in its 17 acquired from three tidal stations, while the wave simulation results trajectory.
    [Show full text]
  • THE PHILIPPINES Schedule of Specific Commitments (For the First
    ASEAN-KOREA AGREEMENT ON TRADE IN SERVICES ANNEX/SC1 ________________________________________________________________________ THE PHILIPPINES Schedule of Specific Commitments (For the First Package of Commitments) 1 AK-ATS/SC1/PHI PHILIPPINES – SCHEDULE OF SPECIFIC COMMITMENTS Modes of supply 1) Cross-border supply 2) Consumption abroad 3) Commercial presence 4) Presence of natural persons Sector or Sub sector Limitations on Market Access Limitations on National Treatment Additional Commitments I. HORIZONTAL COMMITMENTS Unbound* means unbound due to lack of technical feasibility. ALL SECTORS INCLUDED 3) In Activities Expressly Reserved by Law 3) Access to Domestic Credit IN THIS SCHEDULE to Citizens of the Philippines (i.e. foreign equity is limited to a minority share): A foreign firm, engaged in non- manufacturing activities availing The participation of foreign investors in itself of peso borrowings, shall the governing body of any corporation observe, at the time of borrowing, engaged in activities expressly the prescribed 50:50 debt-to- reserved to citizens of the Philippines equity ratio. Foreign firms covered by law shall be limited to the are: proportionate share of foreign capital of such entities. a) Partnerships, more than 40 per cent of whose capital is All executive and managing officers owned by non-Filipino must be citizens of the Philippines. citizens; and Acquisition of Land b) Corporations, more than 40 per cent of whose total All lands of the public domain are subscribed capital stock is owned by the State. owned by non-Filipino citizens. Only citizens of the Philippines or corporations or association at least 60 This requirement does not apply to per cent of whose capital is owned by banks and non-bank financial such citizens may own land other than intermediaries public lands and acquire public lands through lease.
    [Show full text]
  • News Release A
    a News release § Swiss Re estimates its third quarter claims burden from large natural catastrophes at USD 1.1 billion; large man-made losses to be an additional USD 300 million Swiss Re estimates its preliminary combined claims burden from Media Relations, recent large natural catastrophes at approximately USD 1.1 billion, Zurich net of retrocession and before tax, dominated by weather-related Telephone +41 43 285 7171 losses in Japan New York In addition, large man-made catastrophe events are expected to Telephone +1 914 828 6511 lead to a pre-tax claims burden of approximately USD 300 million Singapore While the third quarter losses are large for an individual quarter for Telephone +65 6232 3302 Swiss Re, the cumulative losses for the first nine months are broadly in line with year-to-date expectations Investor Relations, Zurich Zurich, 18 October 2018 – Swiss Re estimates its preliminary claims Telephone +41 43 285 4444 burden from recent natural catastrophes amount to approximately USD 1.1 billion in the third quarter of 2018, net of retrocession and Swiss Re Ltd before tax. Claims from Typhoon Jebi are expected to be Mythenquai 50/60 CH-8022 Zurich USD 500 million. The claims burden from Hurricane Florence is expected to be USD 120 million. A number of further natural Telephone +41 43 285 2121 catastrophes, mainly in Japan (including torrential rains/floods, Fax +41 43 285 2999 Typhoon Trami) and North America (such as the Carr Wildfire in California and a windstorm in Ontario) aggregate to another www.swissre.com USD 500 million of large losses for Swiss Re in the quarter.
    [Show full text]
  • 1990) and Gene (1990
    DECEMBER 1999 WU AND CHENG 3003 An Observational Study of Environmental In¯uences on the Intensity Changes of Typhoons Flo (1990) and Gene (1990) CHUN-CHIEH WUANDHSIU-JU CHENG Department of Atmospheric Sciences, National Taiwan University, Taipei, Taiwan (Manuscript received 27 July 1998, in ®nal form 22 December 1998) ABSTRACT The European Centre for Medium-Range Weather Forecasts Tropical Ocean±Global Atmosphere advanced analysis was used to study the mechanisms that affect the intensity of Typhoons Flo (1990) and Gene (1990). The out¯ow structure, eddy momentum ¯ux convergence, and the mean vertical wind shear were examined. The evolution of potential vorticity (PV) in the out¯ow layer showed low PV areas on top of both Typhoons Flo and Gene, and the low PV areas expanded as the typhoons intensi®ed. The out¯ow pattern of the two typhoons was in¯uenced by the upper-tropospheric environmental systems. The upper-level environmental fea- tures were shown to play a crucial role in the intensi®cation of the two typhoons. The tropical upper-tropospheric trough cell east of Flo provided the out¯ow channel for the typhoon. The enhanced out¯ow, the upper-level eddy ¯ux convergence (EFC), the low vertical wind shear, and the warm sea surface temperature provided all favorable conditions for the development of Flo. On the other hand, the intensi®cation of Gene was associated with its interaction with an upper-level midlatitude trough. The approach of the trough produced upper-level EFC of angular momentum outside 108 lat radius, and the EFC shifted inward with time.
    [Show full text]
  • Large Intensity Changes in Tropical Cyclones: a Case Study of Supertyphoon Flo During TCM-90
    3556 MONTHLY WEATHER REVIEW VOLUME 128 Large Intensity Changes in Tropical Cyclones: A Case Study of Supertyphoon Flo during TCM-90 DAVID W. T ITLEY AND RUSSELL L. ELSBERRY Department of Meteorology, Naval Postgraduate School, Monterey, California (Manuscript received 5 November 1998, in ®nal form 5 May 1999) ABSTRACT A unique dataset, recorded during the rapid intensi®cation and rapid decay of Typhoon Flo, is analyzed to isolate associated environmental conditions and key physical processes. This case occurred during the Tropical Cyclone Motion (TCM-90) ®eld experiment with enhanced observations, especially in the upper troposphere beyond about 300 km. These data have been analyzed with a four-dimensional data assimilation technique and a multiquadric interpolation technique. While both the ocean thermal structure and vertical wind shear are favorable, they do not explain the rapid intensi®cation or the rapid decay. A preconditioning phase is de®ned in which several interrelated factors combine to create favorable conditions: (i) a cyclonic wind burst occurs at 200 mb, (ii) vertical wind shear between 300 and 150 mb decreases 35%, (iii) the warm core is displaced upward, and (iv) 200-mb out¯ow becomes larger in the 400±1200-km radial band, while a layer of in¯ow develops below this out¯ow. These conditions appear to be forced by eddy ¯ux convergence (EFC) of angular momentum, which appears to act in a catalyst function as proposed by Pfeffer and colleagues, because the EFC then decreases to small values during the rapid intensi®cation stage. Similarly, the outer secondary circulation decreases during this stage, so that the rapid intensi®cation appears to be an internal (within 300 km) adjustment process that is perhaps triggered during the preconditioning phase.
    [Show full text]
  • Title Characteristics of Landslides in Unwelded Pyroclastic Flow Deposits
    Characteristics of landslides in unwelded pyroclastic flow Title deposits, southern Kyushu, Japan Author(s) Yamao, M.; Sidle, R. C.; Gomi, T.; Imaizumi, F. Natural Hazards and Earth System Sciences (2016), 16(2): 617- Citation 627 Issue Date 2016-03-03 URL http://hdl.handle.net/2433/216389 © Author(s) 2016. This work is distributed under the Creative Right Commons Attribution 3.0 License. Type Journal Article Textversion publisher Kyoto University Nat. Hazards Earth Syst. Sci., 16, 617–627, 2016 www.nat-hazards-earth-syst-sci.net/16/617/2016/ doi:10.5194/nhess-16-617-2016 © Author(s) 2016. CC Attribution 3.0 License. Characteristics of landslides in unwelded pyroclastic flow deposits, southern Kyushu, Japan M. Yamaoa,†, R. C. Sidle1, T. Gomi2, and F. Imaizumi3 1Sustainability Research Centre, University of the Sunshine Coast, Locked Bag 4, Maroochydore DC, Queensland 4558, Australia 2Department of International Environmental and Agriculture Science, Tokyo University of Agriculture and Technology, Saiwai 3-5-8, Fuchu, Tokyo, 1585809, Japan 3Faculty of Agriculture, Shizuoka University, 836, Ohya, Suruga-ku, Shizuoka, 4228529, Japan aformerly at: Disaster Prevention Research Institute, Kyoto University, Gokasho, Uji, Kyoto, 6110011, Japan †deceased Correspondence to: R. C. Sidle ([email protected]) Received: 5 September 2015 – Published in Nat. Hazards Earth Syst. Sci. Discuss.: 27 October 2015 Revised: 22 January 2016 – Accepted: 29 January 2016 – Published: 3 March 2016 Abstract. We investigated 184 landslides that occurred in thresholds we have identified are useful for predicting the oc- unwelded pyroclastic flow deposits (Shirasu) on southern currence of different types of landslides in unwelded Shirasu Kyushu Island, Japan, that included detailed data on the rain- deposits and improving sediment disaster prevention prac- fall characteristics and the timing of slope failure.
    [Show full text]
  • 1990) and Gene (1990
    DECEMBER 1999 WU AND CHENG 3003 An Observational Study of Environmental In¯uences on the Intensity Changes of Typhoons Flo (1990) and Gene (1990) CHUN-CHIEH WUANDHSIU-JU CHENG Department of Atmospheric Sciences, National Taiwan University, Taipei, Taiwan (Manuscript received 27 July 1998, in ®nal form 22 December 1998) ABSTRACT The European Centre for Medium-Range Weather Forecasts Tropical Ocean±Global Atmosphere advanced analysis was used to study the mechanisms that affect the intensity of Typhoons Flo (1990) and Gene (1990). The out¯ow structure, eddy momentum ¯ux convergence, and the mean vertical wind shear were examined. The evolution of potential vorticity (PV) in the out¯ow layer showed low PV areas on top of both Typhoons Flo and Gene, and the low PV areas expanded as the typhoons intensi®ed. The out¯ow pattern of the two typhoons was in¯uenced by the upper-tropospheric environmental systems. The upper-level environmental fea- tures were shown to play a crucial role in the intensi®cation of the two typhoons. The tropical upper-tropospheric trough cell east of Flo provided the out¯ow channel for the typhoon. The enhanced out¯ow, the upper-level eddy ¯ux convergence (EFC), the low vertical wind shear, and the warm sea surface temperature provided all favorable conditions for the development of Flo. On the other hand, the intensi®cation of Gene was associated with its interaction with an upper-level midlatitude trough. The approach of the trough produced upper-level EFC of angular momentum outside 108 lat radius, and the EFC shifted inward with time.
    [Show full text]
  • Significant Data on Major Disasters Worldwide, 1900-Present
    DISASTER HISTORY Signi ficant Data on Major Disasters Worldwide, 1900 - Present Prepared for the Office of U.S. Foreign Disaster Assistance Agency for International Developnent Washington, D.C. 20523 Labat-Anderson Incorporated Arlington, Virginia 22201 Under Contract AID/PDC-0000-C-00-8153 INTRODUCTION The OFDA Disaster History provides information on major disasters uhich have occurred around the world since 1900. Informtion is mare complete on events since 1964 - the year the Office of Fore8jn Disaster Assistance was created - and includes details on all disasters to nhich the Office responded with assistance. No records are kept on disasters uhich occurred within the United States and its territories.* All OFDA 'declared' disasters are included - i.e., all those in uhich the Chief of the U.S. Diplmtic Mission in an affected country determined that a disaster exfsted uhich warranted U.S. govermnt response. OFDA is charged with responsibility for coordinating all USG foreign disaster relief. Significant anon-declared' disasters are also included in the History based on the following criteria: o Earthquake and volcano disasters are included if tbe mmber of people killed is at least six, or the total nmber uilled and injured is 25 or more, or at least 1,000 people art affect&, or damage is $1 million or more. o mather disasters except draught (flood, storm, cyclone, typhoon, landslide, heat wave, cold wave, etc.) are included if the drof people killed and injured totals at least 50, or 1,000 or mre are homeless or affected, or damage Is at least S1 mi 1l ion. o Drought disasters are included if the nunber affected is substantial.
    [Show full text]