Table Of Content

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Unclassified Security Classification ofthis page REPORT DOCUMENTATION PAGE la Report Security Classification: Unclassified lb Restrictive Markings 2a Security Classification Authority 3 Distribution/AvailabilityofReport 2b Declassification/Downgrading Schedule Approved for public release; distribution is unlimited. 4 Performing Organization Report Number(s) 5 Monitoring OrganizationReport Number(s) 6a Name ofPerforming Organization 6b Office Symbol 7a Name ofMonitoring Organization MR Naval Postgraduate School (ifapplicable) Naval Postgraduate School 6c Address (city, state, andZIPcode) 7b Address (city, state, andZIP code) Monterey CA 93943-5000 Monterey CA 93943-5000 8a Name ofFunding/Sponsoring Organization 6b Office Symbol 9 Procurement Instrument Identification Number (ifapplicable) Address (city, state, andZIP code) 10Source ofFunding Numbers Program Element No Project No Task No Work Unit Accession No AN INVESTIGATION OF THE ERICA IOP-5A CYCLONE 11 Title(include security classification) 12 Personal Author(s) Spinelli, Julia M. 13a Type ofReport 13b TimeCovered 14 Date ofReport (year, month, day) 15 PageCount Master's Thesis From To December 1992 114 16 Supplementary Notation The views expressed in this thesis are those ofthe author and do not reflect the official policy or position ofthe Department of Defense or the U.S. Government. 17 Cosati Codes 18 Subject Terms (continue on reverse ifnecessary andidentify by block number) Field Group Subgroup Experiment on Rapidly Intensifying Cyclones over the Atlantic (ERICA) IOP-5A, rapid cyclogenesis, NORAPS, mesoscale coastal cyclogenesis. 19 Abstract (continue on reverse ifnecessary and identify by blocknumber) A synoptic investigation was conducted of the rapid coastal cyclogenesis event that occurred during Intensive Observation Period (ICP) 5A of the Experiment on Rapidly Intensifying Cyclones over the Atlantic (ERICA). Navy Operational Regional Analysis and Prediction System (NORAPS) objective analyses, utilizing operationally available and some special ERICA data, were examined in order to study the environment in which rapid development took place and to determine key synoptic and subsynoptic features important in the evolution ofthis storm. Additionally, the ability of NORAPS to accurately simulate the rapid cyclogenesis was investigated. Several processes contributed to the storm's intense development including strong low tropospheric temperature advection and upper-level cyclonic vorticity advection and divergence associated with a mobile trough andjet streak. NORAPS forecasts initialized 12 h prior to the explosive deepening phase ofthe IOP-5A cyclone provided a reasonably accurate simulation ofthe event. However, subjective hand analyses ofhourly data for the period surrounding the onset of rapid deepening revealed the presence ofa mesoscale coastal cyclone, which influenced the development ofthe storm. The development of this separate cyclone was not resolved by the model, resulting in a forecast track north ofthe actual storm's path. 20 Distribution/AvailabilityofAbstract 21 Abstract Security Classification xx unclassified/unlimited _ same as report DTIC users Unclassified 22a Name ofResponsible Individual 22b Telephone (include Area Code) 22c Office Symbol Wash, Carlyle H. (408) 656-2295 MR/Wx DD FORM 1473,84 MAR 83 APRedition may be used until exhausted security classification ofthis page All other editions areobsolete Unclassified T258590 Approvedfor public release; distribution is unlimited. An Investigation ofthe ERICAIOP-5ACyclone by Julia M. Spinelli Lieutenant, United StatesNavy B.S., United States NavalAcademy, 1985 Submittedin partial fulfillment ofthe requirements forthe degree of MASTEROF SCIENCE IN METEOROLOGY AND PHYSICAL OCEANOGRAPHY fromthe NAVALPOSTGRADUATE SCHOOL December 1992 ABSTRACT A synoptic investigation was conducted of the rapid coastal cyclogenesis event that occurred during Intensive Observation Period (IOP) 5A of the Experiment on Rapidly Intensifying Cyclones over the Atlantic (ERICA) Navy Operational Regional . Analysis and Prediction System (NORAPS) objective analyses, utilizing operationally available and some special ERICA data, were examined in order to study the environment in which rapid development took place and to determine key synoptic and subsynoptic features important in the evolution of this storm. Additionally, the ability of NORAPS to accurately simulate the rapid cyclogenesis was investigated. Several processes contributed to the storm's intense development including strong low tropospheric temperature advection and upper- level cyclonic vorticity advection and divergence associated with a mobile trough and jet streak. NORAPS forecasts initialized 12 h prior to the explosive deepening phase of the I0P-5A cyclone provided a reasonably accurate simulation of the event. However, subjective hand analyses of hourly data for the period surrounding the onset of rapid deepening revealed the presence of a mesoscale coastal cyclone, which influenced the development of the storm. The development of this separate cyclone was not 111 resolved by the model, resulting in a forecast track north of the actual storm's path. IV OUDLEY KNOX LIBRARY NAVALPOSTGRADUATESCHOOt MONTEREY.CALIFORNIA93943-500; TABLE OF CONTENTS I. INTRODUCTION 1 .... A. THE SIGNIFICANCE OF RAPID CYCLOGENESIS 1 B. RECENT CLIMATOLOGICAL STUDIES/RESEARCH PROJECTS 1 C. THE EXPERIMENT ON RAPIDLY INTENSIFYING CYCLONES OVER THE ATLANTIC (ERICA) 3 D. THESIS OBJECTIVES 5 II. BACKGROUND 7 A. PREVIOUS STUDIES OF THE PROCESSES CONTRIBUTING TO RAPID CYCLOGENESIS 7 ... B. NUMERICAL MODELLING OF RAPID CYCLOGENESIS 12 ... 1. National Meteorological Center Models 12 2. The Navy Operational Regional Atmospheric Prediction System (NORAPS) 12 III. SYNOPTIC DISCUSSION 15 A. 1200 UTC 20 JANUARY 1989 15 B. 1800 UTC 20 JANUARY 1989 19 C. 0000 UTC 21 JANUARY 1989 24 D. 0600 UTC 21 JANUARY 1989 29 E. 1200 UTC 21 JANUARY 1989 35 F. 1800 UTC 21 JANUARY 1989 41 . G. 0000 UTC 22 JANUARY 1989 42 H. MESOSCALE ANALYSES AND THE EXAMINATION OF TOPOGRAPHIC/COASTAL INFLUENCES 50 IV. NORAPS MODEL PERFORMANCE 60 A. MODEL DESCRIPTION 60 B. POSITION AND INTENSITY 61 C. LOW-LEVEL THICKNESS/THERMAL FEATURES 62 D. MID-LEVEL VORTICITY FEATURES 64 .... E. UPPER-LEVEL JET AND DIVERGENCE FEATURES 68 F. SUMMARY 71 V. VERTICAL MOTION ANALYSIS 72 ... A. METHODS OF CALCULATING VERTICAL VELOCITY 72 ... B. COMPARISONS OF VERTICAL MOTION ESTIMATES 75 1. 1800 UTC 20 January 1989 76 2. 0000 UTC 21 January 1989 78 3. 0600 UTC 21 January 1989 81 4. 1200 UTC 21 January 1989 83 5. 1800 UTC 21 January 1989 85 6 Summary 87 VI. CONCLUSIONS AND RECOMMENDATIONS 89 A. CONCLUSIONS 89 B. RECOMMENDATIONS 91 vi