APRIL 1998 NOTES AND CORRESPONDENCE 1091

Statistical Analysis of the Characteristics of Severe Hitting the Japanese Main Islands

TAKESHI FUJII General Education and Research Center, Kyoto Sangyo University, Kyoto, 5 May 1997 and 19 July 1997

ABSTRACT Characteristics of 51 severe typhoons hitting the Japanese main islands with central pressure equal to or less than 980 hPa during the period 1955±94 were analyzed by an objective method using hourly station observation during passages. Position of a typhoon center, central pressure depth ⌬p, and radius of the maximum

wind rm, were obtained at hourly intervals after landfall on the main islands of Japan. The pressure pro®le of severe typhoons used in this analysis was chosen from formulas presented in previous papers, namely the same as one used by the U.S. Army Corps of Engineers for hurricanes hitting . Coastlines of the main islands were divided into three sections: areas A, B, and C extending from west to east. Statistical analyses of parameters were made for each area. At time of landfall, the maximum value of ⌬p was 83.2 hPa for area A, 85.2 hPa for area B, and 47.8 hPa for area C. The differences in return period of ⌬p among areas are considered to be caused by the SST distribution off the Paci®c coast. On average, typhoons

making landfall in area C have larger rm and speed, and display a more eastward component of translation than those in the other two areas. The differences of speed and direction among areas and months can be explained to be caused by variation of the synoptic-scale air current at the 500-hPa level.

1. Introduction suta and Fujii 1986). The 51 severe typhoons making landfall on the Japanese main islands in this period In most parts of western Japan, severe natural dis- with the central pressure equal to or less than 980 hPa asters have mainly been caused by typhoons. In 1959, were analyzed by ®tting to the pressure pro®le for- (Isewan) caused a high and mula by Schloemer. more than 5000 deaths. Recently, of 1991 damaged about 680 000 wooden houses, and losses paid by insurance amounted to 600 billion yen 2. Experimental formula for pressure pro®le of (about 5 billion U.S.). Statistical images of such se- a typhoon vere typhoons hitting Japan are ®gured out in this Mature stage tropical cyclones are characterized by paper. their concentric pressure patterns. The pressure dis- The author has presented an objective analysis tribution can be given by one radial pressure pro®le. method of pressure patterns of typhoons ®tting a pre- The formula chosen to represent typhoons hitting the scribed pressure formula (Fujii 1974). Using this Japanese islands by a previous study (Mitsuta et al. method, the author and collaborators chose the best 1979) is one proposed by Schloemer (1954), namely, ®t formula for tropical cyclones hitting the Japanese main islands from various formulas presented previ- 1 ously (Mitsuta et al. 1979), to be the one used by the p ϭ pc ϩ⌬p exp Ϫ , (1) U.S. Corps of Engineers. (Schloemer 1954) for hur- ΂΃x ricanes hitting Florida. where p is the sea level pressure at the radial distance

In this study, pressure patterns of typhoons making r, pc is the pressure at a typhoon center, ⌬p ϭ pϱ Ϫ landfall on the Japanese main islands were reanalyzed p c ( pϱ is peripheral pressure) de®ned as the central for a 40-yr period from 1955 to 1994 including those pressure depth, and x ϭ r/r m (r m is radius of the max- analyzed in previous studies (Mitsuta et al. 1979; Mit- imum wind speed). Holland (1980) has extended this equation by add- ing another parameter, B, to represent small-scale tropical cyclones in Australia: Corresponding author address: Takeshi Fujii, General Education and Research Center, Kyoto Sangyo University, Kamigamo, Kita, 1 Kyoto 603-8555, Japan. p ϭ pc ϩ⌬p exp Ϫ . (2) E-mail: [email protected] ΂΃xB

᭧ 1998 American Meteorological Society

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This formula was applied to the estimation of the estimates of the typhoon center (␾, ␭ ), r m , ⌬p, and storm surge in Bangladesh by Hubbert et al. (1991) ␴ p , were determined. and Flather (1994). Hubbert et al. also presented an In this study, the distance increment was reduced experimental relation representing increase of B with from 0.02Њ used in a previous study (Mitsuta and Fujii decreasing p c . 1986) to 0.01Њ, and the interval of r m was reduced Using Eq. (2), Fujii and Mitsuta (1995) analyzed from 1 to 0.5 km. The outer boundary of the analysis pressure patterns of three typhoons, Mireille of 1991, region also extended from 200 to 250 km from the Yancy of 1993, and Orchid of 1994, that made landfall typhoon center. Data from approximately 20±40 sta- on the Japanese main islands in recent years with tions could be used at each hour. Results of the anal- strong intensity. Their results showed that pressure ysis of 51 severe typhoons over 40 years are sum- patterns can be approximated reasonably with B ϭ marized in Table 1. Detailed hourly data for each ty- 1.0. This implies that pressure pro®les of intense ty- phoon are compiled in a database, which is available phoons reaching the Japanese main islands in mid- upon request. latitudes may be represented by Eq. (1) without any serious error. So, in this study Eq. (1) is used. 4. Statistical characteristics at time of landfall 3. Method of the objective analysis Most severe typhoons approach Japan from the The pressure distribution formula, Eq. (1), was ®t- southwest along the periphery of the Paci®c Ocean ted to an hourly sea level at over the warm Kuroshio Current. They are in a mature weather stations of the Japanese Meteorological stage, but some are already weakened after its peak. Agency (JMA) within about 250 km of the typhoon While the Japanese main islands extend from south- center by the least square method for each typhoon. southwest to north-northeast, typhoons hitting them

In this process, the following weighting function, w r , are a little different in nature between the western and was applied in order to get a close ®tting to the ob- eastern parts of Japan. The Paci®c coasts of the main served sea level pressures near the typhoon center: islands of Japan were divided into three areasÐA, B, and CÐas shown in Fig. 1a. These were 20 out of 51 typhoons that made landfall in area A, 19 in area B, 100  , r Ͼ 10 km and 12 in area C. The time of landfall is de®ned as  r w ϭ (3) the ®rst hour after a typhoon pressure center crosses r  the smoothed coastline as shown in Fig. 1a. Direction 10, r Յ 10 km. and speed of the typhoon movement at landfall are The ®tting process starts from a given central position de®ned as the vector difference between hourly ty-

(latitude ␾ and longitude ␭) and an initial rm. The ®rst phoon positions just before landfall and at landfall. estimation of ⌬p was computed by using the method of The distribution of (SST) least squares. The initial central position, (␾, ␭), can be in August is also shown in Fig. 1b, in relation to a rough estimate that may be the position of the weather comparison of typhoon intensities among areas. station showing the minimum pressure, and initial rm may also be 80 km, which is the average by the previous a. Central pressure depth, ⌬p study (Mitsuta and Fujii 1986). Root-mean-square error,

␴p, was computed from the difference between com- From the annual maximum values of ⌬p at time of puted sea level pressures and observed pressures at landfall, return periods are computed by the method weather stations, multiplied by the weighting function of Hazen (1930) for annual peak values for each area. wr shown in Eq. (3) as follows: However, these values cannot be compared among areas due to differences in the length of the coastline. 1/2 w (p Ϫ p )2 ͸ r comp obs So, the widths of the areas looking from the averaged ␴p ϭ , (4) w direction of typhoon translations, which is shown by ͸ r an arrow in Fig. 1a, are 233 km in area A, 348 km where pcomp and pobs are computed and measured sea in area B, and 253 km in area C. Return periods of level pressures at each station. ⌬p are converted into the values per invading width

With successive changes of r m at intervals of 0.5 of 100 km, which are shown in Fig. 2. km, ␴ p is computed. Values of r m and ⌬p, are chosen Expected values for return periods of 50 years per as the set of values showing the minimum ␴ p . Then, 100 km are 73 hPa in area A, 60 hPa in area B, and the typhoon center is shifted by Ϯ0.01Њ in latitude or 43 hPa in area C, and those for 25 years are 63, 57, longitude, and a second estimate of central position and 37 hPa, respectively. is chosen as the position that gives the minimum value Apparent discontinuities are seen from 52 to 64 hPa of ␴ p after adjusting values of r m and ⌬p by the meth- for area A and from 37 to 51 hPa for area B. The od shown above. Repeating this procedure, the best reason is not clear but may be caused by the mixing

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TABLE 1. List of 51 typhoons that made landfall on the Japanese main islands with central pressure below 980 hPa in the period from 1955 to 1994 with the typical parameters obtained by the analysis of this study. At landfall Time change rate Area of

Typhoon Typhoon land- ⌬p rm C ␥ ap ar ac ad Year name number fall (hPa) (km) (km hϪ1) (Њ) (10Ϫ2 hϪ1) (km hϪ1) (km hϪ2) (Њ hϪ1) 1955 Louise 5522 A 63.8 97.5 29 Ϫ17 4.9 4.3 2.9 6.8 1956 Harriet 5615 C 30.9 67.0 54 55 Ð Ð Ð Ð 1957 Bess 5710 A 48.2 84.5 35 44 6.4 5.0 Ϫ3.9 Ϫ5.6 1958 Helen 5821 C 46.5 118.0 47 45 3.5 5.3 5.0 2.9 1958 Ida 5822 C 42.8 44.0 34 52 21.2 8.0 5.7 Ϫ8.0 1959 Ellen 5906 B 21.6 146.0 26 40 1.2 4.5 1.9 3.9 1959 Vera 5915 B 85.2 105.5 45 12 11.9 12.3 6.9 2.1 1960 Della 6016 B 29.4 68.0 50 22 6.4 4.9 0.4 Ϫ3.2 1961 Nancy 6118 B 69.0 75.0 39 31 8.0 4.5 7.9 0.3 1961 Violet 6124 C 35.4 104.0 101 45 Ð Ð Ð Ð 1963 Bess 6309 A 31.4 105.0 29 25 7.0 9.7 Ϫ3.9 Ϫ11.6 1964 Kathy 6414 A 40.0 77.5 13 Ϫ4 2.1 1.5 Ϫ0.3 3.5 1964 Wilda 6420 A 83.2 50.5 33 29 9.7 6.7 0.6 1.7 1965 Jean 6515 A 50.6 50.5 37 29 11.7 10.2 3.6 Ϫ3.4 1965 Lucy 6517 C 37.9 26.0 31 27 18.5 4.3 Ϫ5.7 4.0 1965 Shirley 6523 B 59.9 67.0 55 16 8.9 5.5 6.0 2.3 1965 Trix 6524 C 41.2 106.0 66 27 7.9 20.0 4.6 0.4 1966 Ida 6626 C 47.8 30.0 50 23 Ð Ð Ð Ð 1967 Dinah 6734 B 33.9 79.0 52 21 Ð Ð Ð Ð 1968 Mary 6804 B 27.0 267.5 47 Ϫ52 1.6 Ϫ11.5 Ϫ3.4 3.7 1969 Cora 6909 A 43.1 54.0 40 64 4.2 3.4 Ϫ1.8 Ϫ2.1 1970 Olga 7002 B 27.9 77.5 28 Ϫ26 9.9 7.2 0.0 Ϫ0.1 1970 Wilda 7009 A 47.7 56.0 26 47 7.2 5.9 2.4 Ϫ0.9 1970 Anita 7010 B 52.0 102.5 21 Ϫ30 6.2 3.7 5.0 4.1 1971 Olive 7119 A 38.1 71.0 27 36 6.8 3.5 1.4 Ϫ9.2 1971 Trix 7123 A 33.1 123.5 24 18 0.9 Ϫ0.8 Ϫ2.3 1.9 1972 Tess 7209 A 21.2 99.5 15 Ϫ63 3.1 Ϫ3.4 5.7 7.1 1972 Helen 7220 B 54.4 93.0 53 22 7.7 15.0 3.3 0.1 1974 Polly 7416 B 31.3 88.0 30 Ϫ35 9.3 9.3 3.2 3.2 1975 Rita 7506 B 31.6 90.0 23 24 2.8 3.5 2.0 0.9 1976 Fran 7617 A 42.4 81.0 19 27 7.4 12.7 3.4 2.4 1979 Owen 7916 B 56.8 40.5 49 35 14.8 7.7 3.9 2.5 1979 Tip 7920 B 29.0 117.5 64 38 5.9 17.5 9.4 0.9 1980 Orchid 8013 A 26.9 273.0 76 6 1.0 Ϫ29.4 Ϫ6.4 1.2 1981 Ogden 8110 A 32.3 36.5 22 Ϫ42 9.2 3.2 2.0 Ϫ1.7 1981 Thad 8115 C 38.6 261.0 48 26 0.8 Ϫ4.8 10.2 Ϫ4.0 1982 Cecil 8210 C 23.2 102.0 72 4 1.8 4.4 Ϫ6.8 Ϫ2.6 1982 Ellis 8213 A 40.9 82.0 18 24 5.0 6.8 3.4 Ϫ3.8 1982 Judy 8218 C 36.2 122.5 34 29 12.2 18.4 6.4 Ϫ2.1 1982 Ken 8219 B 29.5 111.0 41 12 9.2 12.3 2.8 Ϫ4.2 1983 Abby 8305 C 20.0 88.5 29 11 2.9 1.8 Ϫ3.1 Ϫ5.7 1985 Irma 8506 C 30.4 106.0 81 51 1.5 11.3 2.3 Ϫ1.3 1985 Pat 8513 A 52.3 52.0 42 Ϫ6 7.9 5.0 2.7 0.7 1987 Kelly 8719 B 36.8 110.5 44 34 9.6 14.2 2.6 Ϫ2.2 1989 Roger 8917 B 25.4 108.0 38 24 3.5 15.1 Ϫ0.3 4.4 1990 Flo 9019 B 59.6 74.0 40 56 10.7 6.7 2.0 Ϫ4.6 1991 Kinna 9117 A 42.2 72.0 40 30 10.8 9.7 2.5 Ϫ1.7 1991 Mireille 9119 A 69.0 83.5 67 61 6.8 14.6 11.0 Ϫ4.5 1992 Janis 9210 A 50.9 83.0 38 38 7.3 9.8 Ϫ0.6 Ϫ1.8 1993 Yancy 9313 A 77.1 56.0 44 28 10.0 9.1 1.7 Ϫ8.5 1994 Orchid 9426 B 59.5 49.5 28 39 16.1 12.3 6.3 Ϫ5.9

of developing and decaying stage typhoons in areas b. Radius of the maximum wind, rm A and B, where warm seawater with SST above 28ЊC is distributed at 100 km off the Paci®c coast, as shown The radius of the maximum wind speed, rm, is one in Fig. 1b. On the other hand, almost all of the ty- index of the horizontal scale of a typhoon as seen in phoons making landfall in area C, where SST is lower Eq. (1). The frequency distribution of rm at landfall is than 27ЊC, are in the decaying stage, and thus there shown in Fig. 3. For 27 out of 51 analyzed severe ty- is no apparent discontinuity. These complicated prob- phoons, rm is in the range of 50±100 km. The frequency ability curves for each area may also suggest dif®culty of typhoons with a large value of rm is larger in the in typhoon statistics. eastern area than in the western area, and averages of

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rm in each area are 84 km in area A, 98 km in area B, and 98 km in area C.

The relation of rm to ⌬p at landfall is shown in Fig. 4. As seen in this ®gure, severe typhoons have small values of rm. The correlation coef®cients between rm and ⌬p are Ϫ0.40 for typhoons making landfall in area A and Ϫ0.39 for those in area B, and there is a weak but signi®cant relation. However, for typhoons making landfall in area C, rm has no signi®cant correlation to ⌬p, which may be the result of no typhoons having high intensity, (⌬p exceeding 50 hPa). After trial with several functions, it is assumed that rm decreases logarithmically with ⌬p, and the best-®t curves for areas A and B are represented in Fig. 4. No signi®cant differences between these curves is seen. The best-®t curve for all areas is drawn, and it shows that rm is 93 km for ⌬p ϭ 40 hPa, 72 km for ⌬p ϭ 60 hPa, and 56 km for ⌬p ϭ 80 hPa. c. Speed of translation, C Occurrence frequencies of typhoon speed, C, at time of landfall are shown in Fig. 5. As a whole, 32 out of 51 severe typhoons have speeds of 20±50 km hϪ1. Av- erage speeds in each area are 34 km hϪ1 (ϭ9.4msϪ1) in area A, 41 km hϪ1 (ϭ11.3 m sϪ1) in area B, and 54 km hϪ1 (ϭ15.0 m sϪ1) in area C. The differences among these areas are considered to be caused by differences of the steering current speeds in the middle and upper troposphere. Monthly mean FIG. 1. (a) Division of the Paci®c coast of the Japanese main islands. Broken lines represent smoothed coast lines, and a circle indicates a values and standard deviations of wind speed at the 500- location of a weather station, where K, S, and T are abbreviations hPa level averaged over the period of 1961±80 are for Kagoshima, Shionmisaki, and Tateno, respectively. (b) The cli- shown in Table 2. Kagoshima, Shionomisaki, and Ta- matological SST distribution in August in the sea area around the teno are located near the Paci®c coasts in areas A, B, Japanese main islands. SST is the average value over the period 1961± and C, respectively, as seen in Fig. 1a. The average 94, based on the dataset of SST over the western North Paci®c com- piled by JMA. An arrow indicates an averaged direction of typhoon wind speeds of the four months from July to October translation, 23Њ measured clockwise from the north. are 12.3 m sϪ1 at Kagoshima, 14.2 m sϪ1 at Shionom- isaki, and 15.7 m sϪ1 at Tateno. The averaged typhoon speeds correspond to 0.8±1.0 time the mean wind speed air current at the 500-hPa level is weak, as seen in Table at the 500-hPa level. 2, and the steering current ¯ows westward occasionally As seen in Table 2, the wind at the 500-hPa level has with northward shifting of the subtropical ridge. a signi®cant variation from month to month, and it is the weakest in August and the highest in October. In Fig. 5, almost all typhoons in August have slow trans- 5. Time change after landfall lation speeds, below 50 km hϪ1, and three of the four Of the 51 typhoons analyzed, 47 could be traced for typhoons in October have fast speeds exceeding 50 km more than 5 h after landfall with central pressures below hϪ1. Therefore, scattering over a wide range of typhoon 990 hPa. Time changes in typhoon characteristics after speeds is considered to be caused by variations in landfall were analyzed for these typhoons. strength of the synoptic-scale steering current. a. The ®lling rate of ⌬p d. Direction of motion, ␥ Generally, intense typhoons have larger ®lling rates Typhoon direction ␥ is measured clockwise from the than weak ones (e.g., Tuleya et al. 1984). So, the ®lling north, and frequency distributions of ␥ at landfall are rate of ⌬p with time, t, after landfall can be shown as shown in Fig. 6. In areas A and B, some typhoons made the function of ⌬p after Matano (1956) as follows; landfall with the westward translating components. Al- d⌬p most all of these typhoons made landfall in July or ϭϪa ⌬p, (5) August. In these months, the west±east component of dt p

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FIG. 3. Frequency distributions of radii of maximum wind speed, r , at landfall. FIG. 2. Expected values of central pressure depth ⌬p as a function m of return period. Return periods were estimated by the method of Hazen (1930). The abscissa is drawn with a double exponential scale. b. Time changes of other parameters Other parameters of typhoons, radius of maximum where a is a parameter representing a typhoon ®lling p winds rm, and translation speed C, and direction ␥ are rate. Therefore, ⌬p decreases exponentially with t as, assumed to be expressed by linear trends as follows:

⌬p ϭ⌬p 0 exp(Ϫapt), (6) r r at mmϭ 0 ϩ r  where ⌬p 0 is ⌬p at the time of landfall. Rapid decrease C ϭ C0 ϩ atc , (7) of ap with increasing rmo has been reported by this author  (Fujii 1987) because lateral mixing is more effective ␥ ϭ ␥0 ϩ atd  than bottom or surface friction on typhoon ®lling when there is no energy supply from the sea surface. Averages Ϫ1 Ϫ1 of ap are 0.065 h in area A, 0.080 h in area B, and 0.078 hϪ1 in area C. It is noted that typhoons making land®ll in area A had the small ®lling rate.

In Fig. 7, ap is shown as a function of rm0, which is rm at landfall. The values of ap are correlated with those of rm0 inversely with the correlation coef®cients of Ϫ0.64 for typhoons in area A, Ϫ0.66 in area B, and Ϫ0.64 in area C. The best-®t curves are shown in this ®gure, on the assumption of exponentially decreasing ap with rm0. The regression curves indicate no signi®cant difference among areas. For all typhoons, the correlation coef®cient between rm0 and ap is Ϫ0.58, and the best-®t curve is also shown in Fig. 7. This curve gives the ®lling rates of 0.13 hϪ1 Ϫ1 for rm0 ϭ 50 km and 0.05 h for rm0 ϭ 100 km. FIG. 4. Relation between ⌬p and rm at landfall.

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FIG. 5. Same as Fig. 3 except for translation speed C.

FIG. 6. Same as Fig. 3 except for translation direction ␥. where ar, ac, and ad are new parameters representing a time change rate and suf®x 0 denotes the value at land- fall. upper layer inside of the eyewall with reduction of en- Ϫ1 Values of ar range from Ϫ29 to 20 km h . Out of ergy supply in the eyewall and rising of the sea level the 47 typhoons investigated, 29 show time changes of pressure at a typhoon center, and, as a result, decreasing Ϫ1 rm in the range 0±10 km h . Averages in each area are of the pressure gradient force in the vicinity of rm.It 4.9 km hϪ1 in area A, 7.5 km hϪ1 in area B, and 8.1 km may resemble the expanding of the maximum wind ra- hϪ1 in area C. dius after AgI crystal seeding in a hurricane modi®-

Increase of rm with typhoon decay is considered to cation experiment (e.g., Anthes 1982). be caused by the weakening of the warm core in the The rate of change of typhoon translation is equiv-

TABLE 2. Average (avg.) and standard deviation (SD) of wind speeds (m sϪ1) at the 500-hPa level (1200 UTC) averaged over the period from 1961 to 1980 (Japan Meteorological Agency 1983). July August September October 4-month Station Avg. SD Avg. SD Avg. SD Avg. SD avg. Kagoshima W±E component 5.1 1.0 1.8 3.6 8.9 3.3 16.4 3.1 S±N component 1.0 1.6 1.4 1.8 2.7 1.7 2.5 1.6 Total speed 9.9 2.1 8.3 1.6 12.5 2.9 18.3 2.9 12.3 Shionomisaki W±E component 7.0 4.3 3.7 3.9 11.6 3.4 18.4 3.4 S±N component 0.4 1.7 1.5 2.0 3.6 2.2 4.7 1.9 Total speed 11.5 2.3 9.6 1.8 14.6 2.9 21.0 2.9 14.2 Tateno W±E component 8.8 3.7 6.9 3.7 14.6 3.7 20.3 3.4 S±N component Ϫ0.4 1.8 1.0 1.7 4.5 2.8 5.6 2.3 Total speed 12.0 2.6 10.0 2.6 17.4 3.2 23.2 3.1 15.7

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SST and synoptic-scale air current at the 500-hPa level. A study on a relation of typhoon deepening and ®lling to SST will be published by this author in the near future. Wide scattering of typhoon speed and direction frequency distributions depended on variation of the air current at the 500-hPa level with month. Results shown here could be synthesized and used in constructing a typhoon model in various disaster pre- vention works.

Acknowledgments. The author would like to express his thanks to Professor Yasushi Mitsuta of Kyoto Uni- versity for many helpful comments. He would also like to thank the Japan Meteorological Agency for providing the surface meteorological data and the Northwest Pa- ci®c SST Data Set.

REFERENCES Anthes, R. 1982: Tropical CyclonesÐTheir Evolution, Structure and

FIG. 7. The relation between exponential ®lling rate, ap,of⌬p and Effects. Meteor. Monogr., No. 41, Amer. Meteor. Soc. 208 pp.

radius of maximum wind speed, rm0, at landfall. Flather, R. A., 1994: A storm surge prediction model for the northern Bay of Bengal with application to the cyclone disaster in April 1991. J. Phys. Oceanogr., 24, 172±190. Fujii, T. 1974: An objective analysis on surface pressure ®eld in alent to typhoon acceleration/deceleration. Out of 47 typhoon region (in Japanese). Acta Humanistica et Scienti®ca typhoons, 34 are in the range of 0±10 km hϪ2, with an Universitatis Sangio Kyotiensis, 4-1, 77±90. average of 1.4 km hϪ2 for typhoons having made landfall , 1987: An analysis of typhoon ®lling after landfall on the Jap- in area A, 3.3 km hϪ2 in area B, and 2.8 km hϪ2 in area anese Islands. Acta Humanistica et Scienti®ca Universitatis San- gio Kyotiensis, 17-1, 62±84. C. Typhoons that made landfall in area A had small , and Y. Mitsuta, 1995: On the radial pressure pro®les of typhoons acceleration. (in Japanese). Ann. Disas. Prev. Res. Kyoto Univ., 38 B±1, 101± Time changes in typhoon center direction are mostly 116. within Ϯ5Њ hϪ1, and they are small for several hours Hazen, A., 1930: Flows. John Wiley and Sons, 200 pp. after landfall. Holland, G. J., 1980: An analytic model of the wind and pressure pro®les in hurricanes. Mon. Wea. Rev., 108, 1212±1218. Hubbert, G. D, G. J. Holland, L. M. Leslie, and M. J. Manton, 1991: 6. Concluding remarks A real-time system for forecasting storm surges. Wea. Forecasting, 6, 86±97. Objective analyses were made for 51 severe typhoons Japan Meteorological Agency, 1983: Aerological Data of Japan, 30- year Period Averages (1951±1980), Part 2. Japan Meteor. Agen- hitting the Japanese main islands with central pressures cy, 576 pp. below 980 hPa at landfall within the 40-yr period from Matano, H., 1956: On the role of the lateral mixing in the cyclos- 1955 to 1994, to obtain typhoon parameters based upon trophic ¯ow pattern in the atmosphere. J. Meteor. Soc. Japan, sea level pressure data. The pressure pro®le formula 34, 125±136. used in this analysis is the exponential type, the same Mitsuta, Y., and T. Fujii, 1986: Analysis of typhoon pressure patterns over Japanese Islands (II). J. Natl. Disas. Sci., 8±2, 19±28. used by the U.S. Army Corps of Engineers for analysis , , and K. Kawahira, 1979: Analysis of typhoon pressure of hurricanes hitting Florida. patterns over Japanese Islands. J. Natl. Disas. Sci., 1±1, 3±19. These analyses can be made objectively without map Schloemer, R. W., 1954: Analysis and synthesis of hurricane wind analyses and may be used in real-time monitoring of patterns over Lake Okeechobee, Florida. Hydrometeor. Rep., 31, 49 pp. typhoon movement. Tuleya, R. E., M. A. Bender, and Y. Kurihara, 1984: A simulation The statistics of the analyzed parameters indicated study of the landfall of tropical cyclones using a moval nested- good correspondence to climatological distributions of mesh model. Mon. Wea. Rev., 112, 124±136.

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