ON THE RELATIONSHIPS BETWEEN THE UNUSUAL TRACK OF TYPHOON MORAKOT (0908) AND THE UPPER WESTERLY TROUGH

FEI Jian-fang; LI Bo; HUANG Xiao-gang; CHENG Xiao-ping

doi:10.3969/j.issn.1006-8775.2012.02.008

Abstract:

In this paper, by carrying out sensitivity tests of initial conditions and diagnostic analysis of physical fields, the impact factors and the physical mechanism of the unusual track of Morakot in the Taiwan Strait are discussed and examined based on the potential vorticity (PV) inversion. The diagnostic results of NCEP data showed that Morakot's track was mainly steered by the subtropical high. The breaking of a high-pressure zone was the main cause for the northward turn of Morakot. A sensitivity test of initial conditions showed that the existence of upper-level trough was the leading factor for the breaking of the high-pressure zone. When the intensity was strengthened of the upper-level trough at initial time, the high-pressure zone would break ahead of time, leading to the early northward turn of Morakot. Conversely, when the intensity was weakened, the breaking of the high-pressure zone would be delayed. Especially, when the intensity was weakened to a certain extent, the high-pressure zone would not break. The typhoon, steered by the easterly flow to the south of the high-pressure zone, would keep moving westward, with no turn in the test. The diagnostic analysis of the physical fields based on the sensitivity test revealed that positive vorticity advection and cold advection associated with the upper-level trough weakened the intensity of the high-pressure zone. The upper-level trough affected typhoon's track indirectly by influencing the high-pressure zone.

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FEI Jian-fang, LI Bo, HUANG Xiao-gang, et al. ON THE RELATIONSHIPS BETWEEN THE UNUSUAL TRACK OF TYPHOON MORAKOT (0908) AND THE UPPER WESTERLY TROUGH [J]. Journal of Tropical Meteorology, 2012, 18(2): 187-194, https://doi.org/10.3969/j.issn.1006-8775.2012.02.008

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ON THE RELATIONSHIPS BETWEEN THE UNUSUAL TRACK OF TYPHOON MORAKOT (0908) AND THE UPPER WESTERLY TROUGH

Institute of Meteorology, PLA University of Science and Technology, Nanjing 211101 China

Received Date: 2011-09-30

Rev Recd Date: 2012-02-15

Abstract: In this paper, by carrying out sensitivity tests of initial conditions and diagnostic analysis of physical fields, the impact factors and the physical mechanism of the unusual track of Morakot in the Taiwan Strait are discussed and examined based on the potential vorticity (PV) inversion. The diagnostic results of NCEP data showed that Morakot's track was mainly steered by the subtropical high. The breaking of a high-pressure zone was the main cause for the northward turn of Morakot. A sensitivity test of initial conditions showed that the existence of upper-level trough was the leading factor for the breaking of the high-pressure zone. When the intensity was strengthened of the upper-level trough at initial time, the high-pressure zone would break ahead of time, leading to the early northward turn of Morakot. Conversely, when the intensity was weakened, the breaking of the high-pressure zone would be delayed. Especially, when the intensity was weakened to a certain extent, the high-pressure zone would not break. The typhoon, steered by the easterly flow to the south of the high-pressure zone, would keep moving westward, with no turn in the test. The diagnostic analysis of the physical fields based on the sensitivity test revealed that positive vorticity advection and cold advection associated with the upper-level trough weakened the intensity of the high-pressure zone. The upper-level trough affected typhoon's track indirectly by influencing the high-pressure zone.

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[1]	CHEN Lian-shou, XU Xiang-de, LUO Zhe-xian. An introduction to tropical cyclone dynamic [M]. Beijing: China Meteorological Press, 2002: 316pp (in Chinese).
[2]	ZHANG Sheng-jun, CHEN Lian-shou, XU Xiang-de. The diagnoses and numerical simulation on the unusual track of Helen (9505) [J]. Chin. J. Atmos. Sci., 2005, 29(6): 937-946 (in Chinese).
[3]	FAN Jun-hong, LI Yun-chuan, CHEN Xiao-lei, et al. The analysis of track turning eastward of typhoon Matsa and the test of NWP [[J]. Sci. Meteor. Sinica, 2007, 27(S1): 134-139 (in Chinese).
[4]	XU Jing, CHEN Lian-shou, XU Xiang-de. Diagnosis of the impact of middle troposphere circulation pattern over the Qinghai-Xizang plateau on the track of typhoon over west Pacific [J]. Quart. J. Appl. Meteor., 1999, 10(4): 410-420 (in Chinese).
[5]	HOSKINS B J, McINTYRE M E, ROBERTSON A. On the use and significance of isentropic potential vorticity maps [J]. Quart. J. Roy. Meteor. Soc., 1985, 111(470): 877-946.
[6]	DAVIS C A, EMANUEL K A. Potential vorticity diagnostics of cyclogenesis [J]. Mon. Wea. Rev., 1991, 119(8): 1929-1953.
[7]	WU C C, EMANUEL K A. Potential vorticity diagnostics of hurricane movement. Part I: A case study of Hurricane Bob (1991) [J]. Mon. Wea. Rev., 1995, 123(1): 69-92.
[8]	WU C C, EMANUEL K A. Potential vorticity diagnostics of hurricane movement.Part II：Tropical storm Ana (1991) and Hurricane Andrew (1992) [J]. Mon. Wea. Rev., 1995, 123(1): 93-109.
[9]	WU C C, HUANG T S, CHOU K H. Potential vorticity diagnosis of the key factors affection the motion of Typhoon Sinlaku (2002) [J]. Mon. Wea. Rev., 2004, 132(8): 2084-2093.
[10]	JI Liang. The numerical simulation of the effect of mid-latitude and subtropical systems on landfall tropical cyclone [D]. Ph.D. dissertation, 2007 (in Chinese).
[11]	JI Liang, FEI Jian-fang, HUANG Xiao-gang. Numerical simulation of the effect of the subtropical high on landfalling tropical cyclones [J]. Acta Meteor. Sinica, 2010, 68(1): 40-47(in Chinese).
[12]	ZHANG Da-lin, KIEU C Q. Potential vorticity diagnosis of a simulated hurricane. Part II: Quasi-balanced contributions to forced secondary circulations [J]. J Atmos. Sci., 2006, 63(11): 2898-2914.
[13]	WANG Xing-bao, ZHANG Da-lin. Potential vorticity diagnosis of a simulated hurricane. Part I: Formulation and quasi-balanced flow [J]. J. Atmos. Sci., 2003, 60(13): 1593-1607.
[14]	KIEU C Q, ZHANG Da-lin. A piecewise potential vorticity inversion algorithm and its application to hurricane inner-core anomalies [J]. J. Atmos. Sci., 2010, 67(8): 2616-2631.
[15]	ARTHUR C P. Geopotential heights and thicknesses as predictors of Atlantic tropical cyclone motion and intensity [J]. Mon. Wea. Rev., 1985, 113(6): 931-939.
[16]	An online poster. How to predict tropical cyclones with the aid of steering airflows? (in Chinese) [EB/OL].[2011-09-30] http://tieba.baidu.com/f?kz=259043629.

ON THE RELATIONSHIPS BETWEEN THE UNUSUAL TRACK OF TYPHOON MORAKOT (0908) AND THE UPPER WESTERLY TROUGH

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