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Effects of Landfall Location and the Approach Angle of a Cyclone Vortex Encountering a Mesoscale Mountain Range
SEPTEMBER 2011 L I N A N D S A V A G E 2095 Effects of Landfall Location and the Approach Angle of a Cyclone Vortex Encountering a Mesoscale Mountain Range YUH-LANG LIN Department of Physics, and Department of Energy & Environmental Systems, and NOAA ISET Center, North Carolina A&T State University, Greensboro, North Carolina L. CROSBY SAVAGE III Wind Analytics, WindLogics, Inc., St. Paul, Minnesota (Manuscript received 3 November 2010, in final form 30 April 2011) ABSTRACT The orographic effects of landfall location, approach angle, and their combination on track deflection during the passage of a cyclone vortex over a mesoscale mountain range are investigated using idealized model simulations. For an elongated mesoscale mountain range, the local vorticity generation, driving the cyclone vortex track deflection, is more dominated by vorticity advection upstream of the mountain range, by vorticity stretching over the lee side and its immediate downstream area, and by vorticity advection again far downstream of the mountain as it steers the vortex back to its original direction of movement. The vorticity advection upstream of the mountain range is caused by the flow splitting associated with orographic blocking. It is found that the ideally simulated cyclone vortex tracks compare reasonably well with observed tracks of typhoons over Taiwan’s Central Mountain Range (CMR). In analyzing the relative vorticity budget, the authors found that jumps in the vortex path are largely governed by stretching on the lee side of the mountain. Based on the vorticity equation, this stretching occurs where fluid columns descend the lee slope so that the rate of stretching is governed mostly by the flow speed and the terrain slope. -
Improvement of Wind Field Hindcasts for Tropical Cyclones
Water Science and Engineering 2016, 9(1): 58e66 HOSTED BY Available online at www.sciencedirect.com Water Science and Engineering journal homepage: http://www.waterjournal.cn Improvement of wind field hindcasts for tropical cyclones Yi Pan a,b, Yong-ping Chen a,b,*, Jiang-xia Li a,b, Xue-lin Ding a,b a State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098, China b College of Harbor, Coastal and Offshore Engineering, Hohai University, Nanjing 210098, China Received 16 August 2015; accepted 10 December 2015 Available online 21 February 2016 Abstract This paper presents a study on the improvement of wind field hindcasts for two typical tropical cyclones, i.e., Fanapi and Meranti, which occurred in 2010. The performance of the three existing models for the hindcasting of cyclone wind fields is first examined, and then two modification methods are proposed to improve the hindcasted results. The first one is the superposition method, which superposes the wind field calculated from the parametric cyclone model on that obtained from the cross-calibrated multi-platform (CCMP) reanalysis data. The radius used for the superposition is based on an analysis of the minimum difference between the two wind fields. The other one is the direct modification method, which directly modifies the CCMP reanalysis data according to the ratio of the measured maximum wind speed to the reanalyzed value as well as the distance from the cyclone center. Using these two methods, the problem of underestimation of strong winds in reanalysis data can be overcome. Both methods show considerable improvements in the hindcasting of tropical cyclone wind fields, compared with the cyclone wind model and the reanalysis data. -
Effects of Landfall Location and the Approach Angle of a Cyclone Vortex Encountering a Mesoscale Mountain Range
SEPTEMBER 2011 L I N A N D S A V A G E 2095 Effects of Landfall Location and the Approach Angle of a Cyclone Vortex Encountering a Mesoscale Mountain Range YUH-LANG LIN Department of Physics, and Department of Energy & Environmental Systems, and NOAA ISET Center, North Carolina A&T State University, Greensboro, North Carolina L. CROSBY SAVAGE III Wind Analytics, WindLogics, Inc., St. Paul, Minnesota (Manuscript received 3 November 2010, in final form 30 April 2011) ABSTRACT The orographic effects of landfall location, approach angle, and their combination on track deflection during the passage of a cyclone vortex over a mesoscale mountain range are investigated using idealized model simulations. For an elongated mesoscale mountain range, the local vorticity generation, driving the cyclone vortex track deflection, is more dominated by vorticity advection upstream of the mountain range, by vorticity stretching over the lee side and its immediate downstream area, and by vorticity advection again far downstream of the mountain as it steers the vortex back to its original direction of movement. The vorticity advection upstream of the mountain range is caused by the flow splitting associated with orographic blocking. It is found that the ideally simulated cyclone vortex tracks compare reasonably well with observed tracks of typhoons over Taiwan’s Central Mountain Range (CMR). In analyzing the relative vorticity budget, the authors found that jumps in the vortex path are largely governed by stretching on the lee side of the mountain. Based on the vorticity equation, this stretching occurs where fluid columns descend the lee slope so that the rate of stretching is governed mostly by the flow speed and the terrain slope. -
Appendix 8: Damages Caused by Natural Disasters
Building Disaster and Climate Resilient Cities in ASEAN Draft Finnal Report APPENDIX 8: DAMAGES CAUSED BY NATURAL DISASTERS A8.1 Flood & Typhoon Table A8.1.1 Record of Flood & Typhoon (Cambodia) Place Date Damage Cambodia Flood Aug 1999 The flash floods, triggered by torrential rains during the first week of August, caused significant damage in the provinces of Sihanoukville, Koh Kong and Kam Pot. As of 10 August, four people were killed, some 8,000 people were left homeless, and 200 meters of railroads were washed away. More than 12,000 hectares of rice paddies were flooded in Kam Pot province alone. Floods Nov 1999 Continued torrential rains during October and early November caused flash floods and affected five southern provinces: Takeo, Kandal, Kampong Speu, Phnom Penh Municipality and Pursat. The report indicates that the floods affected 21,334 families and around 9,900 ha of rice field. IFRC's situation report dated 9 November stated that 3,561 houses are damaged/destroyed. So far, there has been no report of casualties. Flood Aug 2000 The second floods has caused serious damages on provinces in the North, the East and the South, especially in Takeo Province. Three provinces along Mekong River (Stung Treng, Kratie and Kompong Cham) and Municipality of Phnom Penh have declared the state of emergency. 121,000 families have been affected, more than 170 people were killed, and some $10 million in rice crops has been destroyed. Immediate needs include food, shelter, and the repair or replacement of homes, household items, and sanitation facilities as water levels in the Delta continue to fall. -
Simulating Storm Surge and Inundation Along the Taiwan Coast During Typhoons Fanapi in 2010 and Soulik in 2013
Terr. Atmos. Ocean. Sci., Vol. 27, No. 6, 965-979, December 2016 doi: 10.3319/TAO.2016.06.13.01(Oc) Simulating Storm Surge and Inundation Along the Taiwan Coast During Typhoons Fanapi in 2010 and Soulik in 2013 Y. Peter Sheng1, *, Vladimir A. Paramygin1, Chuen-Teyr Terng 2, and Chi-Hao Chu 2 1 University of Florida, Gainesville, Florida, U.S.A. 2 Central Weather Bureau, Taipei City, Taiwan, R.O.C. Received 10 January 2016, revised 9 June 2016, accepted 13 June 2016 ABSTRACT Taiwan is subjected to significant storm surges, waves, and coastal inundation during frequent tropical cyclones. Along the west coast, with gentler bathymetric slopes, storm surges often cause significant coastal inundation. Along the east coast with steep bathymetric slopes, waves can contribute significantly to the storm surge in the form of wave setup. To examine the importance of waves in storm surges and quantify the significance of coastal inundation, this paper presents numerical simulations of storm surge and coastal inundation during two major typhoons, Fanapi in 2010 and Soulik in 2013, which impacted the southwest and northeast coasts of Taiwan, respectively. The simulations were conducted with an integrated surge-wave modeling system using a large coastal model domain wrapped around the island of Taiwan, with a grid resolution of 50 - 300 m. During Fanapi, the simulated storm surge and coastal inundation near Kaohsiung are not as accurate as those obtained using a smaller coastal domain with finer resolution (40 - 150 m). During Soulik, the model simulations show that wave setup contributed significantly (up to 20%) to the peak storm surge along the northeast coast of Taiwan. -
Typhoon Initialization in a Mesoscale Model — Combination of the Bogused Vortex and the Dropwindsonde Data in DOTSTAR
Typhoon Initialization in a Mesoscale Model — Combination of the Bogused Vortex and the Dropwindsonde Data in DOTSTAR Kun-Hsuan Chou and Chun-Chieh Wu Department of Atmospheric Sciences, National Taiwan University, Taipei, Taiwan Submitted to Monthly Weather Review (Revised on April 23, 2007) ___________________ Corresponding author address: Dr. Chun-Chieh Wu, Department of Atmospheric Sciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 106, Taiwan. ([email protected]) Abstract Issues on the initialization and simulation of tropical cyclones by integrating both the dropwindsonde data and the bogused vortex into a mesoscale model have been studied. A method is proposed to combine the dropwindsonde data with the bogused vortex for the tropical cyclone initialization and to improve the track and intensity prediction. Clear positive impact of this proposed method on both the tropical cyclone track and intensity forecasts in a mesoscale model is demonstrated in three cases of typhoons, Meari (2004), Conson (2004) and Megi (2004). The effectiveness of the proposed method in improving the track and intensity forecasts are also demonstrated in the evaluation of all 10 cases of DOTSTAR (Dropwindsonde Observations for Typhoon Surveillance near the Taiwan Region) missions in 2004. This method provides a useful and practical means to improve the operational tropical cyclones prediction with the dropwindsonde observations. 1 1 Introduction Over the past 30 years, persistent and steady progress on the track forecasts of tropical cyclone (TC) have been well demonstrated through the improvement of the numerical models, the data assimilation and bogusing systems, the targeted observations, and the satellite and dropwindsonde data available to the forecast systems (Wu et al. -
Typhoon Initialization in a Mesoscale Model—Combination of the Bogused Vortex and the Dropwindsonde Data in DOTSTAR
MARCH 2008 CHOU AND WU 865 Typhoon Initialization in a Mesoscale Model—Combination of the Bogused Vortex and the Dropwindsonde Data in DOTSTAR KUN-HSUAN CHOU AND CHUN-CHIEH WU Department of Atmospheric Sciences, National Taiwan University, Taipei, Taiwan (Manuscript received 12 January 2007, in final form 30 May 2007) ABSTRACT Issues concerning the initialization and simulation of tropical cyclones by integrating both dropwindsonde data and a bogused vortex into a mesoscale model have been studied. A method is proposed to combine dropwindsonde data with a bogused vortex for tropical cyclone initialization and to improve track and intensity prediction. A clear positive impact of this proposed method on both the tropical cyclone track and intensity forecasts in a mesoscale model is demonstrated in three cases of typhoons, including Meari (2004), Conson (2004), and Megi (2004). The effectiveness of the proposed method in improving the track and intensity forecasts is also demonstrated in the evaluation of all 10 cases of Dropwindsonde Observations for Typhoon Surveillance near the Taiwan Region (DOTSTAR) missions in 2004. This method provides a useful and practical means to improve operational tropical cyclone prediction with dropwindsonde obser- vations. 1. Introduction been sparse, the uncertainty and poor quality in initial conditions can lead to monumental errors in the nu- Over the past 30 yr, persistent and steady progress on merical simulation and prediction of TCs. For example, the track forecasts of tropical cyclones (TCs) has been Kurihara et al. (1995) have shown that a better predic- well demonstrated through the improvement of nu- tion could be achieved by the use of improved initial- merical models, data assimilation and bogusing sys- ization procedures that better represent the initial en- tems, targeted observations, and satellite and drop- vironment, as well as the vortex-scale, flow, and mass windsonde data available to the forecast systems (Wu fields. -
Annual Weather Review 2010 ______
Annual Weather Review 2010 ____________________________________________________________________________ Review of Weather Conditions in 2010 Northeast Monsoon Season (Jan – March) 2010 started off with a mild Northeast Monsoon, with rainfall well below average for the first two months of the year. Not only was the 2009/2010 Northeast Monsoon unusual in not bringing the monsoon surges typical of the rainy season1, the period also saw the occurrence of Sumatra squalls on three almost consecutive days on 4, 6 and 7 January 2010. Sumatra squalls are associated with deep southwesterly winds and are uncommon during the Northeast Monsoon, during which the prevailing winds are predominantly from the opposite direction. The dry phase2 of the Northeast Monsoon set in during late January 2010 and extended to March 2010. The dry conditions usually experienced during this period are due to the strong cross equatorial flow induced by the migration of the monsoon rain belt far south of the equator away from Singapore. The absence of sufficient moisture coupled with the presence of strong divergent wind flow at the 700-850 hPa levels, impeded convective activity and suppressed rainfall during this period. In February 2010, the coincident passage of a dry phase of the Madden Julian Oscillation (MJO) and a moderate El-Niño over the maritime continent further exacerbated the dry conditions over Singapore and the surrounding region. As a result, February 2010 was the driest February for Singapore since rainfall records began in 1869, with only 6.3 mm of rainfall recorded at the climate station. Moreover, the dry phase of the Northeast Monsoon in 2010 had only 5 rain days and registered a total rainfall of merely 9.8 mm. -
Typhoon Conson
Philippines: Information bulletin n° 1 GLIDE TC-2010-000131-PHL 14 July 2010 Typhoon Conson This bulletin is being issued for information only and reflects the current situation and details available at this time. The Philippine Red Cross, with the support of the International Federation of Red Cross and Red Crescent Societies (IFRC), has determined that external assistance is currently not required, and is therefore not seeking funding or other assistance from donors at this time. <click here to view the map of the affected area, or here for detailed contact information> Typhoon Conson (locally named Basyang) was seen via satellite 660 km east-northeast of Virac, Catanduanes on July 12, 2010 at 4:00 a.m. It intensified and was upgraded to a Tropical Storm at 11:00 p.m. the same day, moving towards the Isabela-Aurora area. The Situation Typhoon Conson (locally known as Basyang) is the second typhoon for the Philippines of a series of some 22 more expected for this year. Conson made landfall early Tuesday night (13 July) as storm warning number 3 was raised in the Aurora province in Northern Quezon, including Polilio Island and Camarines Norte. Public Storm Signal Number 1 was raised in Batangas, Cavite and included Lubang Island, Bataan, Pampanga, Zambales, Tarlac, Pangasinan, Albay, Marinduque, La Union, Benguet, Mt. Province, Ilocos Sur, Kalinga, Apayao, Abra, Cagayan, and Metro Manila. Public Storm Signal Number 2 was raised in Camarines Sur, Southern Quezon, Laguna, Rizal, Bulacan, Nueva Ecija, Nueva Vizcaya, Quirino, Ifugao and Isabela. Meanwhile, Public Storm Signal Number 3 was raised in Catanduanes, Camarines Norte, Northern Quezon, Polilio Island, and Aurora. -
Subsidence Warming As an Underappreciated Ingredient in Tropical Cyclogenesis
NOVEMBER 2015 K E R N S A N D C H E N 4237 Subsidence Warming as an Underappreciated Ingredient in Tropical Cyclogenesis. Part I: Aircraft Observations BRANDON W. KERNS AND SHUYI S. CHEN Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida (Manuscript received 15 December 2014, in final form 15 July 2015) ABSTRACT The development of a compact warm core extending from the mid-upper levels to the lower troposphere and related surface pressure falls leading to tropical cyclogenesis (TC genesis) is not well understood. This study documents the evolution of the three-dimensional thermal structure during the early developing stages of Typhoons Fanapi and Megi using aircraft dropsonde observations from the Impact of Typhoons on the Ocean in the Pacific (ITOP) field campaign in 2010. Prior to TC genesis, the precursor disturbances were characterized by warm (cool) anomalies above (below) the melting level (;550 hPa) with small surface pressure perturbations. Onion-shaped skew T–logp profiles, which are a known signature of mesoscale subsidence warming induced by organized mesoscale convective systems (MCSs), are ubiquitous throughout the ITOP aircraft missions from the precursor disturbance to the tropical storm stages. The warming partially erodes the lower-troposphere (850–600 hPa) cool anomalies. This warming results in increased surface pressure falls when superposed with the upper-troposphere warm anomalies associated with the long-lasting MCSs/cloud clusters. Hydrostatic pressure analysis suggests the upper-level warming alone would not result in the initial sea level pressure drop associated with the transformation from a disturbance to a TC. -
Downloaded 10/01/21 02:24 PM UTC 4916 JOURNAL of the ATMOSPHERIC SCIENCES VOLUME 72
DECEMBER 2015 T A N G E T A L . 4915 Horizontal Transition of Turbulent Cascade in the Near-Surface Layer of Tropical Cyclones JIE TANG Shanghai Typhoon Institute, China Meteorological Administration, Shanghai, and Key Laboratory of Mesoscale Severe Weather, Ministry of Education, and School of Atmospheric Sciences, Nanjing University, Nanjing, China DAVID BYRNE Environmental Physics Group, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich,€ Zurich, Switzerland JUN A. ZHANG National Oceanic and Atmospheric Administration/Atlantic Oceanographic and Meteorological Laboratory/Hurricane Research Division, Miami, Florida YUAN WANG Key Laboratory of Mesoscale Severe Weather, Ministry of Education, and School of Atmospheric Sciences, Nanjing University, Nanjing, China XIAO-TU LEI,DAN WU,PING-ZHI FANG, AND BING-KE ZHAO Shanghai Typhoon Institute, China Meteorological Administration, Shanghai, China (Manuscript received 15 December 2014, in final form 7 July 2015) ABSTRACT Tropical cyclones (TC) consist of a large range of interacting scales from hundreds of kilometers to a few meters. The energy transportation among these different scales—that is, from smaller to larger scales (up- scale) or vice versa (downscale)—may have profound impacts on TC energy dynamics as a result of the associated changes in available energy sources and sinks. From multilayer tower measurements in the low- level (,120 m) boundary layer of several landing TCs, the authors found there are two distinct regions where the energy flux changes from upscale to downscale as a function of distance to the storm center. The boundary between these two regions is approximately 1.5 times the radius of maximum wind. Two-dimensional tur- bulence (upscale cascade) occurs more typically at regions close to the inner-core region of TCs, while 3D turbulence (downscale cascade) mostly occurs at the outer-core region in the surface layer. -
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.