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XU Hui (徐 辉) , LIU Chong-Jian (柳崇健) Vol.14 No.2 JOURNAL OF TROPICAL METEOROLOGY December 2008 Article ID: 1006-8775(2008) 02-0141-04 ENTROPY FLOW CHARACTERISTICS ANALYSIS OF TYPHOON MATSA (0509) 1 2 XU Hui (徐 辉), LIU Chong-jian (柳崇健) (1. National Meteorological Centre, Beijing 100081 China; 2. Chinese Academy of Meteorological Sciences, Beijing 100081 China) Abstract: The evolution of Typhoon Matsa (0509) is examined in terms of entropy flow through an entropy balance equation derived from the Gibbs relation, according to the second law of thermodynamics. The entropy flows in the various significant stages of (genesis, development and decaying) during its evolution are diagnosed based on the outputs of the PSU/NCAR mesoscale model (known as MM5). The results show that: (1) the vertical spatial distribution of entropy flow for Matsa is characterized by a predominantly negative entropy flow in a large portion of the troposphere and a positive flow in the upper levels; (2) the fields of entropy flows at the middle troposphere (500 hPa) show that the growth of the typhoon is greatly dependent on the negative entropy flows from its surroundings; and (3) the simulated centres of heavy rainfall associated with the typhoon match well with the zones of large negative entropy flows, suggesting that they may be a significant indicator for severe weather events. Key words: entropy flow; typhoons; simulation CLC number: P444 Document code: A 1 INTRODUCTION to the system must be less than that as output from it, or, there must be a negative entropy flow. It can be The introduction of the second thermodynamic law th inferred that the presence of a negative entropy flow is in the early 20 century has broadened the scope to a forceful criterion to judge whether an orderly which the discipline can be applied. The interactions dissipative structure has already occurred. It is just and forcings among various irreversible processes in because of it that this study tries to diagnose and non-equilibrium states have become a pivotal point in [1-6] analyze a typhoon process using the concept of thermodynamics development. Previous work has negative entropy flow based on an entropy equilibrium paved the way for both present and future equation derived, in the hope that the result could open comprehensive study of the atmospheric up a new way to predict the track and intensity of thermodynamics. In China, there has already been typhoons. much work on incorporating the theory of dissipative structure into the atmospheric science [7 - 10]. As it 2 ANALYSIS OF THE NUMERICAL involves a lot of approximation in its application, the SIMULATIONS study is still in a growing stage before maturing and few people employ the theory to analyze individual Matsa (0509) was a typhoon that made landfall in weather processes. Taizhou, Zhejiang province, at 3:40 a.m., August 6, Entropy is a core concept in the theory of 2005 and became the most serious storm that ever hit dissipative structure and existing literature has a full [11 - 14] the eastern China and its coast after Winnie (9711), spectrum of coverage about it . The value of which made landfall in Wenling, Zhejiang, August 18, entropy exchange can be either positive or negative 1997 [15 - 17]. Matsa was numerically simulated with while the value of entropy generated is nonnegative. MM5V3 with the domain centered at 24°N, 123°E and Entropy is the product of any system that produces the over 115×126 horizontal gridpoints, 15 km in grid dissipative structure, i.e. the amount of entropy as input Received date: 2007-09-18; revised date: 2008-10-09 Foundation item: Natural Science Foundation of China (40475022; 40333028) Biography: XU Hui, male, native from Zhejiang province, M.S., engineer, mainly undertaking mesoscale numerical simulation. E-mail for correspondence author: [email protected] PDF created with pdfFactory trial version www.pdffactory.com 142 Journal of Tropical Meteorology Vol.14 Fig.1 The migratory track of Matsa every six hours. The solid line is the observed track and the dashed line the simulated track. a b c Fig.2 The distribution of 500-hPa negative entropy flow at the generation and developing stages of Matsa. The black dot is where the typhoon is and the circle is the area of interest. (a), (b) and (c) indicate 06:00 and 18:00 August 2 and 06:00 August 6, 2005, respectively. interval, 23 layers in the vertical direction and 45 s in after decaying. The area of large values of negative time step. The data used include NCEP analysis with a entropy indicates in some way the direction at which resolution of 1°×1° available every six hours between the typhoon moves in the future (Fig.2) while the 00:00 August 1 and 00:00 August 7, 2005. The Grell change in the intensity of negative entropy flow helps scheme is used for cumulus parameterization. The pinpoint in some way the change in typhoon intensity Blakdar scheme is used for the planetary boundary (Fig.3). layer. Due to the limitation of text, this study uses the The migratory track of Matsa is well simulated distribution of the 500-hPa negative entropy flow for using the MM5 (Fig.1). Next, on the basis of the only one of the select time in each of the three stages of numerical simulation output, the equation of entropy developing, maintaining and dissipating to study the equilibrium is used to study the links between the 6-h simulated precipitation (Fig.4). distribution of negative entropy flow and the intensity See the Chinese edition of the journal for more changes of Matsa and typhoon-induced torrential rains. details. The distribution of negative entropy flow varies with the stages of life cycle, when it evolves from the 3 CONCLUSIONS generation to become mature and eventually dissipates PDF crea142t ed with pdfFactory trial version www.pdffactory.com No.2 XU Hui (徐 辉) and LIU Chong-jian (柳崇健) 143 1.5 50 S u r 45 f ) 1 a ) c s 40 e m · K 0.5 35 a ( x / . J w 6 30 0 0 i n 1 ( d g g g g g g g g g g g g g 25 y u u u u u u u u u u u u u s p p -0.5 A A A A A A A A A A A A A e o 1 1 2 2 3 3 4 4 5 5 6 6 6 20 r e t d n Z Z Z Z Z Z Z Z Z Z Z Z Z e 15 ( 0 2 0 2 0 2 0 2 0 2 0 2 0 -1 m l 0 1 0 1 0 1 0 1 0 1 0 1 0 a / t 10 s o ) T -1.5 5 -2 0 total entropy surface max.wind Fig.3 The temporal evolution of general three-dimensional entropy flow at and near the center of Matsa. The time interval is 6 h and the variation of maximum surface wind speed is given as references of comparison. a b c d e f Fig.4 The distributions of 500-hPa negative entropy flow and corresponding precipitation. The black dot is where the typhoon is and the circle is the area of interest. (a), (b) and (c) indicate the 500-hPa negative entropy flow distribution for 06:00 August 3, 06:00 August 5 and 06:00 August 6, 2005, respectively, when Matsa was developing, maintaining and dissipating; (d), (e) and (f) stand for the simulated rainfall 6 hours prior to the corresponding time. In this study, the concept of negative entropy flow characteristics of negative entropy flow associated with in non-linear thermodynamics is used to conduct a the generation, evolution and dissipative stages and at preliminary study of Typhoon Matsa for the different levels of altitude. The following points have PDF created with pdfFactory trial version www.pdffactory.com 143 144 Journal of Tropical Meteorology Vol.14 been summarized. [1] ONSAGER L. Reciprocal relations in irreversible (1) Usually, there are zones of large negative processes.I [J]. Phys. Rev., 1931, 37: 405-426. entropy flow at the lower and middle trosposphere and [2] ONSAGER L. Reciprocal relations in irreversible processes.II [J]. Phys. Rev., 1931, 38: 2 265-2 279. extensive areas of positive entropy flow at the higher [3] PRIGOGINE I. Thermodynamics of irreversible processes troposphere. [J]. Bull. Class. Sci., Acad. Roy. Belg., 1945, 31(5): 600-621. (2) Negative entropy flow is distributed differently [4] PRIGOGINE I. Introduction to thermodynamics of at different stages of the typhoon. At the initial stage of irreversible processes [M]. lllinois: Charles C. Thomas evolution, negative entropy flow appears over a Publisher Springfield, 1955: 1-20. [5] DEGROOT S R, MAZUR P. Non-equilibrium relatively small area with mild intensity; with the thermodynamics [M]. Amsterdam: North-Holland Publishing development and deepening of the typhoon, the flow Company, 1962: 5-25. will increase its coverage and intensity around the eye [6] KATCHALSKY A, CURRAN P F. Nonequilibrium and nearby area; when the typhoon goes beyond the Thermodynamics in Biophysics [M]. Cambridge: Harward strongest point of development, the flow will begin to University Press, 1965: 320. weaken gradually in terms of both coverage and [7] PRIGOGINE I. Introduction to thermodynamics of irreversible processes [M]. lllinois: Charles C. Thomas intensity. Publisher Springfield, 1955: 40-60. (3) The area of intense typhoon-induced [8] LIU Chong-jian. The Theory of Atmospheric Dissipative precipitation is usually corresponding to that of the Structure [M]. Beijing: Meteorological Press, 1988: 101-129. maximum negative entropy flow.
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