Chang, C.-P.

Kuo, H.C.

Liu, C.H.

English

Calhoun, Institutional Archive of the Naval Postgraduate School

Calhoun: The NPS Institutional ArchiveDSpace RepositoryFaculty and Researchers Faculty and Researchers' Publications2012Convection and Shear Flow in TCDevelopment and IntensificationChang, C.-P.; Kuo, H.C.; Liu, C.H.http://hdl.handle.net/10945/69521This publication is a work of the U.S. Government as defined in Title 17, UnitedStates Code, Section 101. Copyright protection is not available for this work in theUnited States.Downloaded from NPS Archive: Calhoun1  DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.   Convection and Shear Flow in TC Development and Intensification  C.-P. Chang Department of Meteorology Naval Postgraduate School, Code MR/Cp Monterey, CA 93943 Telephone 831-656-2840, e-mail cpchang@nps.edu  H.-C. Kuo Department of Meteorology Naval Postgraduate School, Code MR/Cp Monterey, CA 93943 Telephone 831-656-2840, e-mail kuo@as.ntu.edu.tw   C.- H. Liu Department of Meteorology Naval Postgraduate School, Code MR/Cp Monterey, CA 93943 Telephone 831-656-2840, e-mail ching_hwang@yahoo.com   Award # N0001412WX20843   LONG TERM GOALS  To study the dynamic processes of tropical cyclone (TC) development in the western North Pacific through field observational data and theoretical modeling.  OBJECTIVES  The objectives are: (1) to study the convection and vorticity generations in the vortex environment that may lead to the development and intensification of TC; (2) to study the development and evolution of deep moist mesoscale convective system subject to strain effect due to the horizontal shear associated with the vortex rotation; (3) to study the offsetting between (1) and (2); (4) to study nonlinear interactions that may lead to additional strain effects that may impact on the convection in ways that are not yet known.  APPROACH  TCS-08 offers a unique opportunity to collect high resolution data of kinematic and thermodynamic fields to determine the filamentation time, which is a function of total deformations and vorticity. The NRL P-3 aircraft with ELDORA airborne radar made it possible to directly compute the filamentation time at the convection scale, allowing an investigation into the effect of filamentation on the stratiform convection and cumulus convection from the Eldora radar data. The stratiform convection and cumulus convection is classified according to Steiner et al. (1995) with modifications that account for the Report Documentation Page Form ApprovedOMB No. 0704-0188Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering andmaintaining 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, ArlingtonVA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if itdoes not display a currently valid OMB control number. 1. REPORT DATE 2012 2. REPORT TYPE N/A 3. DATES COVERED   -   4. TITLE AND SUBTITLE Convection and Shear Flow in TC Development and Intensification 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Department of Meteorology Naval Postgraduate School, Code MR/CpMonterey, CA 93943 8. PERFORMING ORGANIZATIONREPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S ACRONYM(S) 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 12. DISTRIBUTION/AVAILABILITY STATEMENT Approved for public release, distribution unlimited 13. SUPPLEMENTARY NOTES The original document contains color images. 14. ABSTRACT 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT SAR 18. NUMBEROF PAGES 7 19a. NAME OFRESPONSIBLE PERSON a. REPORT unclassified b. ABSTRACT unclassified c. THIS PAGE unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 2  difference between different types of radars. We have concentrated our effort for TCS025 (a non-developing case), Typhoon Hagupit (2008) in the pre-tropical storm (TS) stage, Typhoon Jangmi (2008) and Typhoon Nuri (2008) in the TS stage, and Typhoon Sinlaku (2008) in the re-intensifying stage.   RESULTS  Our effort this year was to better understand the filamentation dynamics on different types of the convection in the pre-TS and TS stages and in a re-intensifying stage of typhoon.   The report of filamentation dynamics in the re-intensification stage of Typhoon Sinlaku (2008) the previous year has been revised to classify the reflectivity into the convective and  stratiform regimes. The paper has been accepted for publication in the Monthly Weather Review this year. The results suggest that filamentation effects may be important for the deep convective process in the TC environment, and likely relevant to the organization of asymmetric structure and spiral bands. Since filamentation increases with increasing TC intensity, it may play a role in limiting convection particularly in the outer spiral cloud band region.   In this year we examined the filamentation effect on the deep convection and stratiform convection in different stages of TC and also a non-developing case TCS025. Figure 1 shows the visible satellite image for (a) TCS025 on 28 Aug. 2008, (b) Typhoon Hagupit on 15 Sep. 2008, (c) Typhoon Jangmi on 25 Sep. 2008, and (d) Typhoon Nuri on 18 Aug. 2008, respectively. The NRL P-3 flight tracks (red) and the domain for dual-Doppler analysis (blue boxes) are superimposed. The TCS025 is a non-developing case, Typhoon Hagupit on 15 Sep. 2008 is in pre-TS stage, Typhoon Jangmi on 25 Sep. 2008 and Typhoon  Typhoon Nuri on 18 Aug. 2008 are in TS stage. Figure 2 is the NRL P-3 Eldora radar reflectivity at 3km level for the cases illustrated in Fig.1.   Figure 3 is the same as Fig. 2 but for dual-Doppler winds, deep convection zone, vorticity dominate zone (VDZ) and rapid filamentation zone (RFZ). The RFZ is with filamentation times < 40 minutes. The RFZs are hatched in yellow, convective area are shaded in light grey with red outlines, and VDZs are shaded in light green. The black line is the P-3 flight track and the arrow heads indicate the aircraft heading direction. Figure 3 suggests that RFZ is larger in the TS stage (Fig. 3c and Fig. 3d) than in the pre-TS stage (Fig.3b). The non-developing case (Fig.3a), with some rotational wind and VDZ, is with insignificant RFZ.   Figure 4 shows the frequency distribution of the filamentation time (minute) for cumulus convection (strong convection) and stratiform convection (in general weak convection) between 2 km and 4 km heights for the cases illustrated in Fig. 1. Figure 4 suggests that there is more convective and stratiform convections occurred in the RFZ as the TC gets stronger. This is expected from the fact that the filamentation increases with increasing TC intensity. In the non-developing case TCS025 and in the pre-TS stage of Typhoon Hagupit, approximately 2/3 of the convective and stratiform convections occurred outside the RFZ. On the other hand, the rainbands in Typhoon Jiangmi 2008 (Fig. 4c) and Typhoon Nuri 2008 (Fig. 4d) were suppressed by the vortex strain effect. The effect may be small but still systematic and conspicuous. The demarcation occurs at filamentation time ~ 35 min.     3  IMPACT  Our results offer information on the mechanisms governing convection in the early stage of a TC, and suggest that filamentation effects may be important for the deep convective process when TC is in the TS stage or stronger. Since filamentation increases with increasing TC intensity, it may play a role in limiting convection particularly in the outer spiral cloud band region. This information can be helpful in evaluating the maximum intensity of a TC.   Fig 1: The NRL P-3 flight tracks (red) superimposed on visible satellite image for (a) TCS025 on 28 Aug. 2008, (b) Typhoon Hagupit on 15 Sep. 2008, (c) Typhoon Jangmi on 25 Sep. 2008, and (d) Typhoon Nuri on 18 Aug. 2008, respectively. The blue boxes indicate the domain for dual-Doppler analysis. The upper left panels on (b), (c), and (d) are center pressure for corresponded typhoons. The TCS025 is a non-developing case, Typhoon Hagupit is in pre-TS stage, while Typhoons Jiangmi and Nuri are in TS stage. 4    Fig 2: The NRL P-3 Eldora radar reflectivity at 3km level for (a) TCS025 at 0257-0223UTC on 28 Aug. 2008, (b) Typhoon Haupit at 0000-0021 on 15 Sep. 2008, (c) Tyohoon Jangmi at 2358-0036 on 24 Sep. 2008, and (d) Typhoon Nuri at 0139-0211 on 18 Aug. 2008, respectively. The black line is the P-3 flight track and the arrow heads indicate the aircraft heading direction. The color tables are shown in the bottom of each panel.  5    Fig 3: Same as Fig. 2 but for dual-Doppler winds, deep convection zone, vorticity dominate zone (VDZ) and rapid filamentation zone (RFZ). The RFZ is with filamentation times < 40 minutes. The RFZs are hatched in yellow, convective area are shaded in light grey with red outlines, and VDZs are shaded in light green. The black line is the P-3 flight track and the arrow heads indicate the aircraft heading direction. The scale for the wind vector is shown in the bottom right of each panel. The wind vector shown is 4 m s-1 except Fig. 3c is with 6 m s-1. 6    Fig 4: Same as Fig. 2 but for the frequency distribution of filamentation time (minute) for the convective (red) and stratiform (blue) reflectivity near the eye core region between 2 km and 4 km heights. The dashed line in the upper panel is the difference between the two. The unit is the same as the lower panel but the scale is shown at the upper right of the frame.   RELATED PROJECTS  TCS08 projects led by Professors Russ Elsberry, Pat Harr and Michael Montgomery at NPS.  SUMMARY  In this year TCS-08 P3 radar data were used to identify the cumulus/stratiform convections and to compute the filamentation time scale in the case of TCS025 which did not develop into a typhoon despite of initial promising conditions, and three cases that did develop:Typhoon Hagupit 2008, 7  Typhoon Jiangmi 2008, and Typhoon Nuri 2008. In all four cases the results confirm that the impact of filamentation process on the convections increases with the TC intensity.   REFERENCES  Biggerstaff, M. I., and S. A. Listemaa 2000: An improved scheme for convective/stratiform echo classification using radar reflectivity. J. Appl. Meteor., 39, 2129-2150. Rosenfeld, D., E. Amitai, and D. B. Wolff, 1995: Classification of rain regimes by the three-dimensional properties of reflectivity fields. J. Appl. Meteor., 34, 198–211. Rozoff, M. C., W. H. Schubert, B. D. McNoldy, and J. P. Kossin, 2006: Rapid filamentation zones in intense tropical cyclones. J. Atmos. Sci., 63, 325-340. Steiner, M., R. A. Houze Jr., and S. E. Yuter, 1995: Climatological characterization of three-dimensional storm structure from operational radar and rain gauge data. J. Appl. Meteor., 34, 1978–2007.  PUBLICATION  Kuo, H.-C., C.-P. Chang, and C.-H. Liu, 2012: Convection and Shear Flow in Typhoon Development and Intensification: An Observation of Typhoon Silaku during TCS-08. Mon. Wea. Rev., 140, 2806–2817..   

Convection and Shear Flow in TC Development and Intensification

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Convection and Shear Flow in TC Development and Intensification

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