DOCSLIB.ORG

Impact of Resolution Degradation of the Initial Condition on Typhoon Track Forecasts

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Impact of Resolution Degradation of the Initial Condition on Typhoon Track Forecasts 1568 WEATHER AND FORECASTING VOLUME 25 NOTES AND CORRESPONDENCE Impact of Resolution Degradation of the Initial Condition on Typhoon Track Forecasts TAKEMASA MIYOSHI Department of Atmospheric and Oceanic Science, University of Maryland, College Park, College Park, Maryland TAKUYA KOMORI AND HITOSHI YONEHARA Numerical Prediction Division, Japan Meteorological Agency, Tokyo, Japan RYOTA SAKAI River Office, Osaka Prefectural Government, Osaka, Japan MUNENHIKO YAMAGUCHI RSMAS, University of Miami, Miami, Florida (Manuscript received 17 December 2009, in final form 11 May 2010) ABSTRACT The operational numerical weather prediction (NWP) systems at the Japan Meteorological Agency (JMA) indicated that the typhoon track forecasts made by the control member of the ensemble prediction system (EPS) tended to be worse than those made by the high-resolution global NWP. The control forecast of the EPS with horizontal triangular truncation at 319 wavenumbers and 60 vertical levels (T319/L60 resolution) was initialized by eliminating the higher-wavenumber components of the global analysis at T959/L60 reso- lution. When the data assimilation cycle was performed at the lower T319/L60 resolution, the forecast gave typhoon track forecasts closer to the high-resolution global NWP. Therefore, it stands to reason that the resolution transform of the initial condition must be responsible for the degradation of the typhoon track forecasts at least to considerable extent. To improve the low-resolution forecast, two approaches are tested in this study: 1) applying a smoother spectral truncation for the resolution transform and 2) performing non- cycled lower-resolution data assimilation during preprocessing. Results from the single case study of Typhoon Nuri (2008) indicate almost no impact from the former approach, but a significant positive impact when using the latter approach. The results of this study illuminate the importance of considering a model’s resolving capability during data assimilation. Namely, if the initial conditions contain features caused by unresolved scales, degraded forecasts may result. 1. Introduction EPS has a lower resolution than the global NWP system, which is true for the TEPS at a T319/L60 resolution. The The Japan Meteorological Agency (JMA) began to initial conditions for the control forecast of TEPS are operate its global NWP system at a T959/L60 resolution generated by simply eliminating higher-wavenumber in November 2007 (Nakagawa 2009) and its typhoon components of the high-resolution global analyses. Five ensemble prediction system (TEPS) in 2008 (Yamaguchi ensemble perturbations are generated by the singular and Komori 2009; Yamaguchi et al. 2009). Typically, the vector (SV) method (e.g., Buizza 1994), and the plus– minus pairs are added to the control initial conditions. Thus, the ensemble mean of the 11-member initial con- Corresponding author address: Takemasa Miyoshi, Dept. of At- mospheric and Oceanic Science, University of Maryland, College ditions equals the set of control initial conditions. Park, College Park, MD 20742. Operations of the high-resolution global NWP and the E-mail: [email protected] lower-resolution TEPS in 2008 yielded an interesting DOI: 10.1175/2010WAF2222392.1 Ó 2010 American Meteorological Society Unauthenticated | Downloaded 09/29/21 12:12 AM UTC OCTOBER 2010 N O T E S A N D C O R R E S P O N D E N C E 1569 result in that the typhoon track forecasts by the TEPS TABLE 1. List of operational forecasts and experiments. control member tended to have larger errors than Expt Description Resolution the high-resolution global forecasts. Moreover, the 11-member ensemble mean of TEPS ensemble forecast T959_OPE Operational high-resolution NWP T959/L60 TEPS_CTL Operational TEPS control forecast T319/L60 tracks, which was generally better than the single control T319_CYC T319 data assimilation cycle T319/L60 member, was still worse than the single high-resolution T319_TS1 Smooth resolution transform T319/L60 forecasts. The initial conditions were essentially identi- T319_TS2 Noncycled T319 data assimilation T319/L60 cal; the higher-wavenumber components were simply eliminated. The forecast degradation may have been due to the differences among the forecast models. Namely, the developed and investigated TC bogusing and reposi- T959/L60 model may have been more accurate than the tioning methods: for example, the National Centers for T319/L60 model. However, the preoperational investi- Environmental Prediction (NCEP; Lord 1991; Liu et al. gations in 2007 indicated essentially identical performance 2000), NRL (Goerss and Jeffries 1994), the Met Office between the high- and low-resolution models in the case (Heming et al. 1995), and ECMWF [never used in op- where the initial conditions are generated by each in- erations; Serrano and Unden (1994)]. More recent studies dependent data assimilation cycle at each resolution. include that of Wu et al. (2006), who assimilated bogus Therefore, we expect that the forecast degradation was data into a mesoscale model and found that wind data caused by the resolution transformation of the initial con- played an important role in TC prediction due to the ditions. This idea agrees with a commonly accepted hy- geostrophic adjustment of smaller scales. pothesis that the initial conditions are suitable to the The focus of this study is different from those of the model with which the data assimilation cycle is performed. previous studies. Global NWP began to be useful for TC This was our first experience at JMA with clear forecasts only about a decade ago (e.g., Elsberry 1995), forecast degradation due to the resolution transform of and NCEP started the operation of the first EPS around the initial conditions using high-wavenumber elimina- that time (Toth and Kalnay 1993). Because the global tion. C. Reynolds (2010, personal communication) had EPS began to increase the level of resolution and be- a similar experience with the Navy Operational Global came potentially useful for TC forecasts only very re- Atmospheric Prediction System (NOGAPS) at the Naval cently, the need to initialize TCs in a lower-resolution Research Laboratory (NRL), and R. Buizza (2010, per- EPS using a higher-resolution analysis has emerged very sonal communication) mentioned the experience of the recently. This has not been addressed in the literature to European Centre for Medium-Range Weather Forecasts the best of the authors’ knowledge. (ECMWF) with their EPS in terms of the importance In this note, we report the diagnostics obtained by the of resolution change from the high-resolution analysis. operations of high-resolution global NWP and TEPS in However, to the best of the authors’ knowledge, no study 2008. In addition, we propose and test two approaches to published thus far has brought to light the problem of the improve the low-resolution forecasts at a minimal addi- degradation of tropical cyclone (TC) track forecasts. Al- tional cost. Section 2 describes the error statistics of the though it is not easy to identify the exact mechanism for 2008 operational typhoon predictions, in which the skill track degradation, it would be beneficial to report the of the high-resolution global NWP exceeded that of the facts observed in the operational systems, which may TEPS control forecast. In section 3 we test two possible motivate further scientific investigations in the wider re- approaches to improve the low-resolution forecast using search community. a case study of Typhoon Nuri (the 12th typhoon in 2008). Many studies have been published on the initialization Finally, a summary and discussion are provided in section of TCs, including those discussing JMA’s prior devel- 4. For simplicity, we define the short names of the oper- opments (e.g., Iwasaki et al. 1987; Ueno 1989; Ueno and ational forecasts and our experiments in Table 1. Details Onogi 1991; Ueno 1995). Most of the previous studies of the experiments will be described later in section 3. focused mainly on TC bogusing and repositioning methods Following the Japanese operational convention, in this to better initialize TC vortices that are compatible with note the term typhoon includes tropical cyclones in the a model’s resolution when only relatively poor analyses northwestern Pacific with maximum wind speed of greater are available due to the general lack of observations than 34 kt (17.5 m s21). around TCs over the ocean. For example, Kurihara et al. (1993) proposed a method of initializing a high-resolution 2. Statistical fact in 2008 typhoon forecast TC forecast using a low-resolution analysis by replacing a crudely resolved TC in the large-scale analysis with a In daily weather briefings to monitor typhoons in 2008, high-resolution vortex. Many operational centers have the developers of TEPS noticed that TEPS_CTL tended Unauthenticated | Downloaded 09/29/21 12:12 AM UTC 1570 WEATHER AND FORECASTING VOLUME 25 FIG. 1. Typhoon track forecast errors averaged for all typhoon forecasts in 2008. FIG. 2. The best track (BEST) and forecast tracks (T959_OPE, operational high resolution; TEPS_CTL, TEPS control; T319_CYC, T319 data assimilation cycle; T319_TS1, smooth resolution trans- to have larger typhoon track prediction errors than T959_ form; T319_TS2, noncycled T319 data assimilation) of Typhoon OPE. This has been proven correct by a statistical in- Nuri (2008) initialized at 1200 UTC 19 Aug 2008 up to 54 h later. vestigation of forecast track errors for all typhoons that Dots indicate typhoon center positions at every 12 h defined by the occurred in 2008, where T959_OPE has significantly minimum mean SLP. smaller track errors by at least 30 km for forecast lead times longer than or equal to 36 h (Fig. 1). In the present case of Typhoon Nuri analyzed at A possible explanation of this statistical fact is the 1200 UTC 19 August 2008, essentially no observation difference between the forecast models; that is, the T959 was available in the vicinity of the typhoon. Therefore, model provides a more accurate prediction than the the preprocessing of the operational global data assimi- T319 model.
Load more

Recommended publications
  • Scientific Collaborations (2014-2019)
    Scientific Collaborations (2014-2019) NOAA ● National Environmental Satellite, Data and Information Service ○ Center for Satellite Applications and Research ○ CoastWatch ○ National Centers for Environmental Information ○ OceanWatch ● National Marine Fisheries Service ○ Alaska Fisheries Science Center ○ Northeast Fisheries Science Center ○ Northwest Fisheries Science Center ○ Pacific Islands Fisheries Science Center ○ Office of Science and Technology ○ Southeast Fisheries Science Center ○ Southeast Regional Office ○ Southwest Fisheries Science Center ● National Ocean Service ○ U.S. Integrated Ocean Observing System ■ Caribbean Regional Association for Coastal Ocean Observing (CARICOOS) ■ Gulf of Mexico Coastal Ocean Observing System (GCOOS) ● Gulf of Mexico Coastal Acidification Network (GCAN) ■ Mid-Atlantic Coastal Ocean Observing System (MARACOOS) ■ Pacific Islands Ocean Observing System (PacIOOS) ■ Southeast Coastal Ocean Observing Regional Association (SECOORA) ● Southeast Ocean and Coastal Acidification Network (SOCAN) ○ National Centers for Coastal Ocean Science ○ National Geodetic Survey ○ Office of National Marine Sanctuaries ■ Florida Keys National Marine Sanctuary ■ Flower Gardens Bank National Marine Sanctuary ■ National Marine Sanctuary of American Samoa ■ Olympic Coast National Marine Sanctuary ○ Office of Response and Restoration ● National Weather Service ○ Climate Prediction Center ○ Environmental Modeling Center ○ National Centers for Environmental Prediction ○ National Data Buoy Center ○ National Hurricane Center 1 ○ Office
    [Show full text]
  • Recent Advances in Research on Tropical Cyclogenesis
    Available online at www.sciencedirect.com ScienceDirect Tropical Cyclone Research and Review 9 (2020) 87e105 www.keaipublishing.com/tcrr Recent advances in research on tropical cyclogenesis Brian H. Tang a,*, Juan Fang b, Alicia Bentley a,y, Gerard Kilroy c, Masuo Nakano d, Myung-Sook Park e, V.P.M. Rajasree f, Zhuo Wang g, Allison A. Wing h, Liguang Wu i a University at Albany, State University of New York, Albany, USA b Nanjing University, Nanjing, China c Ludwig-Maximilians University of Munich, Munich, Germany d Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan e Korea Institute of Ocean Science and Technology, Busan, South Korea f Centre for Atmospheric and Climate Physics Research, University of Hertfordshire, Hatfield, UK g University of Illinois, Urbana, USA h Florida State University, Tallahassee, USA i Fudan University, Shanghai, China Available online 7 May 2020 Abstract This review article summarizes recent (2014e2019) advances in our understanding of tropical cyclogenesis, stemming from activities at the ninth International Workshop on Tropical Cyclones. Tropical cyclogenesis involves the interaction of dynamic and thermodynamic processes at multiple spatio-temporal scales. Studies have furthered our understanding of how tropical cyclogenesis may be affected by external processes, such as intraseasonal oscillations, monsoon circulations, the intertropical convergence zone, and midlatitude troughs and cutoff lows. Addi- tionally, studies have furthered our understanding of how tropical cyclogenesis may be affected by internal processes, such as the organization of deep convection; the evolution of the “pouch” structure; the role of friction; the development of the moist, warm core; the importance of surface fluxes; and the role of the mid-level vortex.
    [Show full text]
  • List of Participants
    WMO Sypmposium on Impact Based Forecasting and Warning Services Met Office, United Kingdom 2-4 December 2019 LIST OF PARTICIPANTS Name Organisation 1 Abdoulaye Diakhete National Agency of Civil Aviation and Meteorology 2 Angelia Guy National Meteorological Service of Belize 3 Brian Golding Met Office Science Fellow - WMO HIWeather WCRP Impact based Forecast Team, Korea Meteorological 4 Byungwoo Jung Administration 5 Carolina Gisele Cerrudo National Meteorological Service Argentina 6 Caroline Zastiral British Red Cross 7 Catalina Jaime Red Cross Climate Centre Directorate for Space, Security and Migration Chiara Proietti 8 Disaster Risk Management Unit 9 Chris Tubbs Met Office, UK 10 Christophe Isson Météo France 11 Christopher John Noble Met Service, New Zealand 12 Dan Beardsley National Weather Service NOAA/National Weather Service, International Affairs Office 13 Daniel Muller 14 David Rogers World Bank GFDRR 15 Dr. Frederiek Sperna Weiland Deltares 16 Dr. Xu Tang Weather & Disaster Risk Reduction Service, WMO National center for hydro-meteorological forecasting, Viet Nam 17 Du Duc Tien 18 Elizabeth May Webster South African Weather Service 19 Elizabeth Page UCAR/COMET 20 Elliot Jacks NOAA 21 Gerald Fleming Public Weather Service Delivery for WMO 22 Germund Haugen Met No 23 Haleh Kootval World Bank Group 24 Helen Bye Met Office, UK 25 Helene Correa Météo-France Impact based Forecast Team, Korea Meteorological 26 Hyo Jin Han Administration Impact based Forecast Team, Korea Meteorological 27 Inhwa Ham Administration Meteorological Service
    [Show full text]
  • Report on UN ESCAP / WMO Typhoon Committee Members Disaster Management System
    Report on UN ESCAP / WMO Typhoon Committee Members Disaster Management System UNITED NATIONS Economic and Social Commission for Asia and the Pacific January 2009 Disaster Management ˆ ` 2009.1.29 4:39 PM ˘ ` 1 ¿ ‚fiˆ •´ lp125 1200DPI 133LPI Report on UN ESCAP/WMO Typhoon Committee Members Disaster Management System By National Institute for Disaster Prevention (NIDP) January 2009, 154 pages Author : Dr. Waonho Yi Dr. Tae Sung Cheong Mr. Kyeonghyeok Jin Ms. Genevieve C. Miller Disaster Management ˆ ` 2009.1.29 4:39 PM ˘ ` 2 ¿ ‚fiˆ •´ lp125 1200DPI 133LPI WMO/TD-No. 1476 World Meteorological Organization, 2009 ISBN 978-89-90564-89-4 93530 The right of publication in print, electronic and any other form and in any language is reserved by WMO. Short extracts from WMO publications may be reproduced without authorization, provided that the complete source is clearly indicated. Editorial correspon- dence and requests to publish, reproduce or translate this publication in part or in whole should be addressed to: Chairperson, Publications Board World Meteorological Organization (WMO) 7 bis, avenue de la Paix Tel.: +41 (0) 22 730 84 03 P.O. Box No. 2300 Fax: +41 (0) 22 730 80 40 CH-1211 Geneva 2, Switzerland E-mail: [email protected] NOTE The designations employed in WMO publications and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of WMO concerning the legal status of any country, territory, city or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries.
    [Show full text]
  • Minnesota Weathertalk Newsletter for Friday, January 3, 2014
    Minnesota WeatherTalk Newsletter for Friday, January 3, 2014 To: MPR's Morning Edition From: Mark Seeley, Univ. of Minnesota, Dept of Soil, Water, and Climate Subject: Minnesota WeatherTalk Newsletter for Friday, January 3, 2014 HEADLINES -December 2013 was climate near historic for northern communities -Cold start to 2014 -Weekly Weather potpourri -MPR listener questions -Almanac for January 3rd -Past weather -Outlook Topic: December 2013 near historic for far north In assessing the climate for December 2013 it should be said that from the standpoint of cold temperatures the month was quite historic for many northern Minnesota communities, especially due to the Arctic cold that prevailed over the last few days of the month. Minnesota reported the coldest temperature in the 48 contiguous states thirteen times during the month, the highest frequency among all 48 states. Many northern observers saw overnight temperatures drop below -30 degrees F on several occasions. The mean monthly temperature for December from several communities ranked among the coldest Decembers ever. A sample listing includes: -4.1 F at International Falls, 2nd coldest all-time 4.6 F at Duluth, 8th coldest all-time 0.1 F at Crookston, 3rd coldest all-time -3.1 F at Roseau, 3rd coldest all-time 0.3 F at Park Rapids, 3rd coldest all-time -4.4 F at Embarrass, 2nd coldest all-time -4.1 F at Baudette, coldest all-time -3.7 F at Warroad, coldest all-time -2.9 F at Babbitt, coldest all-time -2.8 F at Gunflint Lake, coldest all-time In addition, some communities reported an exceptionally snowy month of December.
    [Show full text]
  • SRNWP-V Programme: a Comparison of Regional European Forecast Models
    SRNWP-V programme: a comparison of regional European forecast models Clive Wilson , Marion Mittermaier Sep 2011 © Crown copyright Met Office Outline & motivation • Short Range Numerical Weather Prediction – EUMETNET programme • Desire to benchmark operational models cf CBS global exchange • Phase 1 2009-2010 • Establish framework, recommend methods • Phase 2 2011-2012 • Continue comparison, more parameters • Use radar/extra observations • Extremal measures © Crown copyright Met Office EUMETNET/SRNWP programme - Deliverables • D1: Operational verification comparison of deterministic forecasts from one version of each of the 4 regional models of Europe (available for all the participating members) • D2: Additional intercomparison of other versions of the consortia models including high resolution models • D3: Inventory and recommendations of “new” scale-selective verification methods. • D4: Catalogue of sources of non-GTS data • D5 Exchange methods and code for verification of severe weather forecasts © Crown copyright Met Office 15km 12km 7km 10km 5 km (10km) Hirlam UM COSMO ALADIN Aladin-Lace © Crown copyright Met Office Parameter Scores Mean sea level mean bias and root mean pressure square errors 2m temperature Bias, rmse 2m relative humidity Bias, rmse mean bias speed error 10m winds and root mean square vector wind error equitable threat score and 6 hourly total frequency bias for 0.5, precipitation 1.0 and 4.0 mm 6h -1 © Crown copyright Met Office Key Model Label Hirlam reference run by FMI UK-FI Aladin-France run by Meteo-France
    [Show full text]
  • Magazine Issue 35 | Improvements to the Seasonal Forecast System and the New UK Climate Projections (UKCP18) Which Come out Next Year
    Barometer Magazine issue 35 | www.metoffice.gov.uk improvements to the seasonal forecast system and the new UK Climate Projections (UKCP18) which come out next year. I also refocused the climate science programme Professor Stephen onto both science and services, and substantially increased Belcher, Met Office Chief our international work, for example through the Climate Scientist, describes his Science for Service Partnership China (CSSP China). passion for his new role Capitalising on the new supercomputer and work addressing the Our new supercomputer was delivered ahead of schedule challenges of big data which has meant that many of the latest science upgrades and climate change. are now going operational and are helping to improve our forecasts (page 19). Leading science A new supercomputer also means huge volumes of data. July 2017 Now, data is one thing, but information is another, so we are Barometer is a controlled circulation magazine looking at intelligent ways of creating useful information distributed free of charge to decision-makers in to services government, science and commerce, for whom and extracting value from that data (page 4). That is where weather and climate information has an impact. the science to service aspect comes in. Improvements to Product information is correct at the time of eing Chief Scientist at the Met Office is a wonderful our weather and climate models will enable development publication but may be subject to change. job because of the broad range of science done of better services, particularly relevant in our support of the For queries about Barometer contact: in the Met Office, as well as the world-leading scientists Government’s emerging Industrial Strategy (page 7) and in Jon Stanford who produce it.
    [Show full text]
  • Public Weather Service Value for Money Review
    Public Weather Service Value for Money Review March 2015 Mike Gray Public Weather Service Customer Group Secretariat Page 1 of 25 Public Weather Service Value for Money Review Executive Summary Through analysing existing studies and literature on the economic value of weather forecasts, and using up to date figures, this review concludes with high confidence that the benefits of the Public Weather Service (PWS) to the UK are very likely to exceed £1bn per annum, and are likely to be close to £1.5bn per annum. This is consistent with the findings of the previous value for money study prepared for the PWS Customer Group (PWSCG) by PA from 2007 which assessed the economic benefits of the PWS at £614m per annum and, given its limited scope, considered the benefits to be many times that figure. Sectors considered in the review were the perceived value to the public (which had an estimated benefit of £480m per annum), value to aviation (£400m per annum), added value to other sectors of the economy (£400m per annum), storm damage avoidance (£80m per annum), value to land transport (£100m per annum) and flood damage avoidance (£64m per annum). Other benefits included the hosting of the European Centre for Medium-range Weather Forecasting (ECMWF) in the UK (£60m per annum) and business of over €200m for the UK space industry by being able to bid for EUMETSAT (the European Organisation for the Exploitation of Meteorological Satellites) contracts by virtue of UK membership paid for by the PWS. It is estimated that the PWS contributes to reducing deaths from high impact weather by many tens per year, and many more during individual severe events such as North Sea coastal flooding.
    [Show full text]
  • Statistical Characteristics of the Response of Sea Surface Temperatures to Westward Typhoons in the South China Sea
    remote sensing Article Statistical Characteristics of the Response of Sea Surface Temperatures to Westward Typhoons in the South China Sea Zhaoyue Ma 1, Yuanzhi Zhang 1,2,*, Renhao Wu 3 and Rong Na 4 1 School of Marine Science, Nanjing University of Information Science and Technology, Nanjing 210044, China; [email protected] 2 Institute of Asia-Pacific Studies, Faculty of Social Sciences, Chinese University of Hong Kong, Hong Kong 999777, China 3 School of Atmospheric Sciences, Sun Yat-Sen University and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519082, China; [email protected] 4 College of Oceanic and Atmospheric Sciences, Ocean University of China, Qingdao 266100, China; [email protected] * Correspondence: [email protected]; Tel.: +86-1888-885-3470 Abstract: The strong interaction between a typhoon and ocean air is one of the most important forms of typhoon and sea air interaction. In this paper, the daily mean sea surface temperature (SST) data of Advanced Microwave Scanning Radiometer for Earth Observation System (EOS) (AMSR-E) are used to analyze the reduction in SST caused by 30 westward typhoons from 1998 to 2018. The findings reveal that 20 typhoons exerted obvious SST cooling areas. Moreover, 97.5% of the cooling locations appeared near and on the right side of the path, while only one appeared on the left side of the path. The decrease in SST generally lasted 6–7 days. Over time, the cooling center continued to diffuse, and the SST gradually rose. The slope of the recovery curve was concentrated between 0.1 and 0.5.
    [Show full text]
  • The Genesis of Typhoon Nuri As Observed During the Tropical Cyclone Structure 2008 (TCS-08) field Experiment – Part 1: the Role of the Easterly Wave Critical Layer
    Atmos. Chem. Phys., 10, 9879–9900, 2010 www.atmos-chem-phys.net/10/9879/2010/ Atmospheric doi:10.5194/acp-10-9879-2010 Chemistry © Author(s) 2010. CC Attribution 3.0 License. and Physics The genesis of Typhoon Nuri as observed during the Tropical Cyclone Structure 2008 (TCS-08) field experiment – Part 1: The role of the easterly wave critical layer M. T. Montgomery, L. L. Lussier III, R. W. Moore, and Z. Wang Naval Postgraduate School, Monterey, California, USA Received: 5 June 2009 – Published in Atmos. Chem. Phys. Discuss.: 16 September 2009 Revised: 14 April 2010 – Accepted: 25 May 2010 – Published: 20 October 2010 Abstract. An observational and real-time model forecast Real-time forecasts were produced using operational study of the genesis of Typhoon Nuri during the Tropical Cy- global prediction model data to support scientific missions clone Structure 2008 (TCS-08) field campaign in the western during TCS-08. These forecasts were found to be useful North Pacific sector is presented. Analysis and observational in flight planning discussions and predicted Typhoon Nuri’s data show that the surrounding base state is an easterly trade eventual genesis latitude within 1.5 degrees 72 h in advance. wind flow and the precursor disturbance to Typhoon Nuri is an easterly wave that originates in the ITCZ in the Central Pa- cific. This disturbance can be tracked more than 10 days prior to tropical storm formation. An overview of the field data is 1 Introduction presented here using a newly proposed dynamical framework The western North Pacific region is the most active trop- for tropical cyclone formation within the critical layer of an ical cyclone (TC) basin on the earth, responsible for, on easterly wave.
    [Show full text]
  • The Genesis of Typhoon Nuri As Observed During the Tropical Cyclone Structure 2008 (TCS-08) field Experiment – Part 1: the Role of the Easterly Wave Critical Layer
    Atmos. Chem. Phys. Discuss., 9, 19159–19203, 2009 Atmospheric www.atmos-chem-phys-discuss.net/9/19159/2009/ Chemistry © Author(s) 2009. This work is distributed under and Physics the Creative Commons Attribution 3.0 License. Discussions This discussion paper is/has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP if available. The genesis of Typhoon Nuri as observed during the Tropical Cyclone Structure 2008 (TCS-08) field experiment – Part 1: The role of the easterly wave critical layer M. T. Montgomery, L. L. Lussier III, R. W. Moore, and Z. Wang Naval Postgraduate School, Monterey, California, USA Received: 5 June 2009 – Accepted: 12 August 2009 – Published: 16 September 2009 Correspondence to: M. T. Montgomery ([email protected]) Published by Copernicus Publications on behalf of the European Geosciences Union. 19159 Abstract An observational and real-time model forecast study of the genesis of Typhoon Nuri during the Tropical Cyclone Structure 2008 (TCS-08) field campaign in the western North Pacific sector is presented. Analysis and observational data show that the sur- 5 rounding base state flow was an easterly trade wind flow and the precursor disturbance to Typhoon Nuri was an easterly wave that originated in the ITCZ in the Central Pacific and can be tracked more than 10 days prior to tropical storm formation. An overview of the field data is presented here using a newly proposed dynamical framework for tropical cyclone formation within the critical layer of an easterly wave. Despite propa- 10 gating through a hostile environment ripe with strong vertical wind shear and relatively dry air, the easterly wave critical layer protected the proto-vortex and allowed it to gestate until it reached a more favorable environment.
    [Show full text]
  • Intensification and Decay of Typhoon Nuri (2014) Associated with Cold Front and Southwesterly Airflow Observed in Satellite Cloud Images
    Journal of Marine Science and Technology, Vol. 25, No. 5, pp. 599-606 (2017) 599 DOI: 10.6119/JMST-017-0706-1 INTENSIFICATION AND DECAY OF TYPHOON NURI (2014) ASSOCIATED WITH COLD FRONT AND SOUTHWESTERLY AIRFLOW OBSERVED IN SATELLITE CLOUD IMAGES Kuan-Dih Yeh1, Ji-Chyun Liu1, Chee-Ming Eea1, Ching-Huei Lin1, Wen-Lung Lu1, Ching-Tsan Chiang1, Yung-Sheng Lee2, and Ada Hui-Chuan Chen3 Key words: super typhoons, satellite imagery, cold fronts. variety of weather patterns could be observed along the occluded fronts, with the possibility of thunderstorms and cloudy condi- tions accompanied by patchy rain or showers. ABSTRACT This paper presents a framework involving the use of remote sensing imagery and image processing techniques to analyze a I. INTRODUCTION 2014 super typhoon, Typhoon Nuri, and the cold occlusion that Investigating the effects of climate variability and global warm- occurred in the northwestern Pacific Ocean. The purpose of ing on the frequency, distribution, and variation of tropical storms this study was to predict the tracks and profiles of Typhoon (TSs) is valuable for disaster prevention (Gierach and Subrah- Nuri and the corresponding association with the induction of manyam, 2007; Acker et al., 2009). Cloud images provided by cold front occlusion. Three-dimensional typhoon profiles were satellite data can be used to analyze the cloud structures and dy- implemented to investigate the in-depth distribution of the cloud namics of typhoons (Wu, 2001; Pun et al., 2007; Pinẽros et al., top from surface cloud images. The results showed that cold fronts 2008, 2011; Liu et al., 2009; Zhang and Wang, 2009).
    [Show full text]