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A Case Study of Insitu-Aircraft Observations in a Waterspout Producing Cloud

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A Case Study of Insitu-Aircraft Observations in a Waterspout Producing Cloud Calhoun: The NPS Institutional Archive DSpace Repository Theses and Dissertations 1. Thesis and Dissertation Collection, all items 2005-03 A case study of insitu-aircraft observations in a waterspout producing cloud Baskin, Clayton M. Monterey California. Naval Postgraduate School http://hdl.handle.net/10945/2320 Downloaded from NPS Archive: Calhoun NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS A CASE STUDY OF INSITU-AIRCRAFT OBSERVATIONS IN A WATERSPOUT PRODUCING CLOUD by Clayton M Baskin March 2005 Thesis Advisor: Haflidi Jonsson Co-Advisor: Wendell Nuss Approved for public release; distribution is unlimited. THIS PAGE INTENTIONALLY LEFT BLANK REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 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 Management 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 March 2005 Master’s Thesis 4. TITLE AND SUBTITLE: A Case Study of Insitu-Aircraft Observations in a 5. FUNDING NUMBERS Waterspout Producing Cloud 6. AUTHOR(S) Clayton M Baskin 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING Naval Postgraduate School ORGANIZATION REPORT Monterey, CA 93943-5000 NUMBER 9. SPONSORING /MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING N/A 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) An analysis of in-situ aircraft observations collected in the parent cloud of a waterspout is presented. Previous waterspout studies were confined mainly to photometric and model simulated data, no in-situ observations were made internal to the parent cloud. On 27 June 2002 the Cooperative Institute for Remotely Piloted Aircraft Studies (CIRPAS) UV-18A Twin Otter aircraft collected observations in a cloud that had developed in a cloud line, located approximately 15km south of Key West, and that formed a waterspout. This study attempts to analyze the waterspout formation process using these data and through a series of scale interactions, from the synoptic scale down to the individual cloud scale. Based upon the analyzed data a hypothetical formation process is developed. The background synoptic scale flow is shown to establish the necessary ambient shear as a key factor in the waterspout formation. The orientation of mesoscale convergent boundaries and thermodynamic processes, internal to the cloud, proved to be an essential factor in developing the vertical motion patterns necessary for formation of an organized circulation in the shear region and to provide the tipping and stretching of the resultant vortex necessary to account for the waterspout formation. This is consistent with conclusions derived from previous studies. 14. SUBJECT TERMS Waterspout, Aircraft Data, CIRPAS, Synoptic Analysis, Sea Surface 15. NUMBER OF Temperature PAGES 55 16. PRICE CODE 17. SECURITY 18. SECURITY 19. SECURITY 20. LIMITATION CLASSIFICATION OF CLASSIFICATION OF THIS CLASSIFICATION OF OF ABSTRACT REPORT PAGE ABSTRACT Unclassified Unclassified Unclassified UL NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89) Prescribed by ANSI Std. 239-18 i THIS PAGE INTENTIONALLY LEFT BLANK ii Approved for public release; distribution is unlimited. A CASE STUDY OF INSITU-AIRCRAFT OBSERVATIONS IN A WATERSPOUT PRODUCING CLOUD Clayton M. Baskin Captain, United States Air Force B.S., University of South Alabama, 1997 Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN METEOROLOGY from the NAVAL POSTGRADUATE SCHOOL March 2005 Author: Clayton M Baskin Approved by: Haflidi Jonsson Thesis Advisor Wendell Nuss Co-Advisor Philip A. Durkee Chairman, Department of Meteorology iii THIS PAGE INTENTIONALLY LEFT BLANK iv ABSTRACT An analysis of in-situ aircraft observations collected in the parent cloud of a waterspout is presented. Previous waterspout studies were confined mainly to photometric and model simulated data, no in-situ observations were made internal to the parent cloud. On 27 June 2002 the Cooperative Institute for Remotely Piloted Aircraft Studies (CIRPAS) UV-18A Twin Otter aircraft collected observations in a cloud that had developed in a cloud line, located approximately 15km south of Key West, and that formed a waterspout. This study attempts to analyze the waterspout formation process using these data and through a series of scale interactions, from the synoptic scale down to the individual cloud scale. Based upon the analyzed data a hypothetical formation process is developed. The background synoptic scale flow is shown to establish the necessary ambient shear as a key factor in the waterspout formation. The orientation of mesoscale convergent boundaries and thermodynamic processes, internal to the cloud, proved to be an essential factor in developing the vertical motion patterns necessary for formation of an organized circulation in the shear region and to provide the tipping and stretching of the resultant vortex necessary to account for the waterspout formation. This is consistent with conclusions derived from previous studies. v THIS PAGE INTENTIONALLY LEFT BLANK vi TABLE OF CONTENTS I. INTRODUCTION........................................................................................................1 A. BACKGROUND INFORMATION ...............................................................1 B. COLLECTED DATA ......................................................................................2 C. GOALS..............................................................................................................3 II. BACKGROUND ENVIRONMENTAL DATA ........................................................5 A. SYNOPTIC ANALYSIS..................................................................................5 1. 300mb/500mb Analysis........................................................................6 2. 700mb Analysis.....................................................................................6 3. 850mb Analysis.....................................................................................6 4. Surface Analysis...................................................................................8 B. SATELLITLE AND SEA SURFACE TEMPERATURE ANALYSIS.......9 1. Sea Surface Temperature Analysis ....................................................9 2. Satellite Imagery Analysis.................................................................10 C. KEY WEST SKEW-T ANALYSIS ..............................................................10 D. BACKGROUND ENVIRONMENTAL SUMMARY ................................12 III. ANALYSIS OF THE AIRCRAFT DATA...............................................................13 A. COLLECTION METHODS.........................................................................13 1. Payload................................................................................................15 2. Data Presentation Methods...............................................................16 B. DATA ANALYSIS.........................................................................................16 1. Horizontal Wind Field.......................................................................16 2. Temperatures .....................................................................................19 3. Vertical Velocities ..............................................................................20 4. Dew Points ..........................................................................................22 5. Equivalent Potential Temperature...................................................22 6. Rotational Wind Plots........................................................................24 7. Aircraft Sounding ..............................................................................24 IV. DISCUSSION AND SUMMARY .............................................................................29 A. DISCUSSION .................................................................................................29 1. Synoptic Scale.....................................................................................29 2. Mesoscale ............................................................................................30 3. Cloud Scale .........................................................................................30 B. HYPOTHETICAL WATERSPOUT FORMATION PROCESS..............30 C. SUMMARY ....................................................................................................34 D. RECOMMENDATIONS FOR FUTURE WORK......................................35 LIST OF REFERENCES......................................................................................................37
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