Abstract from a Dynamical Point of View, Three Dimensional Analyses Of

551.515.2 An Aerological Investigation of the Structure of the Typhoon - Analyses of the Typhoons Jane and Kezia- by Y. Masuda and M. Takeuchi RescarchMerteorological Institute (Receive (I July 25, 1951) Abstract From a dynamical point of view, three dimensional analyses of the typhoons Jane and Kezia, that is, the analysis of the pressure field, the temperature field, the tropopause and the stream lines, etc. are performed, and a typhoon model deduced from thee analyses is proposed. It is concluded that the typhoon is not a simple convective system, but a system superposed by a few dynamical secondary convective systems, and each meteorolo- gical element corresponds to the distribution of then e systems. 1. Introduction The typhoon is a large cyclonic eddy accompanied with strong winds and heavy rains, bringing about great damage in its passage. Therefore, since former times, studise of forecasting of several phenomena associated with it have been made, and many laws (mainly empirical laws) have been obtained. However, these laws are not reliable yet. This may be partly due to the fact that the three-dimentional structure of the typhoon has not been held exactly. Therefore, it is most necessary to make a detailed three-dimensional analysis of typhoon. Two-dimensional analyses of the typhoon have been performed in some detail using abundant data of surface observations. Especially, Dr. SY0N0 S. [11, [2] showed theoretically the existence of negative vorticity area in the typhoon and he and his collaborators [3] verified this theory after analysing the typhoon from the dynamical point of view. Furthermore, T. Fujita's study of the fine structure of the typhoon Dela [4] is also remarkable. Recently, especially during and after World War II, in company with the development of aerological observation nets, a branch of meteorology, known as tropical synoptic meteorology, has developed and a tendency to study the formation and the structure of the typhoon in its three-dimentional aspect has been growing. However, in this tropical synoptic meteorology there are many difficulties in method of analysis addition to the scarcity of data. That is, thermal methods of analysis familiar in the middle latitudes ---frontal, lapse-rate, and air mass analysis, etc.- -are not useful. The system with which tropical synopic meteorology is concerned has 1951An Aerological Investigation of the Structure of the Typhoon235 a dynamical character and then, in its analysis, dynamical and kinematical methods must be mainly used. Some studies of the three-dimensional structure of the typhoon from these points of view- have been performed. And especially, as some detailed data are gained in the case of the typhoon Kitty, many studies, for example the studies of YAMA_DA H. & MATUHASHI S. [5], of Dr. ARAKAwA H. [6], [7], of HASHIMOTO M. & SAMPE1 J. [8] and of IVIAsuDA Y. [9], . etc. are reported. Conc- erning the hurricane, studies of SimPSON R. H. [10], [11] and PALMEN E. [12] are also remarkable. However, these analyses are all fragmentary and a synthetic analysis has not been performed yet. In this report, from a dynamical point of .view, three-dimensional analyses of the typhoons Jane and Kezi .a are performed by using aerological data of Japan, and a typhoon model deduced from these analyses is proposed. As typhoons, coming near Japan, change their intensities through the mature to the dissipative stage, so the model proposed in this, report belongs to these .stages. In future, it is necessary to settle the typhoon model after accumulations of sufficient data, to study the mechanism of typhoon phenomena theoretically, and further to study applications of aerological data to typhoon forecast in relation to surface data. 2. General aspects The typhoon Jane was born in the area south of Iwozima on about 30 Aug. 1950, moved through the Kinki district of Ja- pan on 3 Sep. , and went away south of Kuril. Islands on 5 Sep.. The scale of this typhoon was smaller than that of the typhoon Mu- roto, but in several places it was strong- er than the later, and wrought great damage. The typhoon Kezia came into existence in the 236Y. Masuda and M. Takeuchi Vlo. 11 Nos.3--4 area north-west of Gum Island on about 7 Sep. 1950, landed in the south of Kylisyet, on 13 Sep entered into the Japan Sea after crossing Ky6syit, and moved away to the Okhotsk Sea on 15 Sep.. Fig. 1 shows the tracks of the typhoons Jane and Kezia, and positions of the aerological observatories using in this report. In this figure, denominators of fractional numbers of side of tracks represent dates, numerators times (in L. M. T. ), and the abbreviations Wak. , Sap. , Mi. , Aki. , Sen. , Tat., Ha. , Waz. , Ko. , Shi. , Yo. , Ita. , Kag. , and Tare represent Wakkanai, Sapporo, Misawa, Akita, Sendai, Tateno, Haneda, Wazima, Komaki, Shionomisaki, Yonago, Itazuke, Kagoshima and the Ocean Station at 135°E, 29°N respectively. These abbreviations will be used throughout this report. Figs. 2 and 3 show relative positions of the main aerological observatories to Jane and Kezia. In these figures, concentric circles represent distances 2°, 4°, 6°, 8° and 10° in latitude from the surface centers. Fig. 4 and 5 indicate the weather charts at those times when Jane and Kezia were located at the Shikoku and the Kyrisyri district respectively. At these times, isobars of the each typhoon system were almost circular and no front was found yet. It is thought that Jane changed into an extratropical cyclone of the temperate latitudes near Hokkaido, and Kezia in the middle of the Japan Sea. Figs. 6 and 7 represent time isopleths for Tare and Wazima in Jane, Fig. 8 space cross-section taking from NE to SE direction through the center of Kezia at 1951 Fig. 6 The temperature and potential temperature isopleth for Tare in Jane. In this figure, full lines represent isotherms for each 5°C, dotted lines isentropic lines for each 5°K, and dashed and dotted line tropopause. 0000 L. M. T. 14 Sep. and Fig. 9 time isopleth for Itazuke in Kezia respectively. In these figures solid lines indicate isotherms for each 5°C, dotted lines isentropic lines for each 5°K, and dashed and dotted lines tropopauses respectively. The definition of tropopause will be seen in paragraph 5. Fig. 6 is the most characteristic among these figures, and from this figure, a warm core which is extremely warm up to. Fig. 7 The temperature and potential temperature isopleth for Wazima in Jane. the upper levels exists at 13.00, 2 Sep. nearest to the typhoon center, and around it fairly cold areas exist. From this fact, it is suggested that areas of strong descending currents exist in the vicinity of the typhoon center and areas of strong ascending currents surround it. As, however, in a humid system such as typhoon, Fig. 8 The temperature and potential temperature cross-section taking from NE to SE direction through the cent(r of Kezia at 0000 L.M. T. 14 Sep. 1950. it occasionally happens that temperature rises when the humid air near the earth surface ascends in wet adiabatic change, so the above description probably does not hold in the lower layers. Other figures are essentially the same as in Fig. 6. However, in these figures time intervals of observations are too long to describe fine structure any more. Fig. 9 The temperature and potential temperature isopleth for itazuke in Kezia. 3. Analysis of the pressure field (a) Vertical pressure distributions In order to investigate vertical pressure distributions in the vicinity of the typhoon, time isopleths for each place and space cross-sections of pressure are 242 , Y. Masuda and M. TakeuchiVol. II Nos. 3-4 drawn. On that occasion, in order to eliminate diurnal variations of pressure and temperature in outline, time isopleths of pressure and temperature anomalies are drawn. The anomalies are computed with respect to the monthly mean values at 0 h, 6 h, 12 h and 18 h in September 1950 at the each aerological station. In this report, " pressure " means heights of standard pressure levels. Figs. 10 (a and b) show distributions of pressure and temperature anomalies for Wazima and Yonago in Jane, and ' Figs. 11 (a arid h) those for Itazuke and Kagoshima in Kezia. In these figures, solid lines represent pressure isanomals for each 40 dyn. m. and dotted lines temperature isanomals for each 2°C. Abscissas of these figures are times of observations and vertical axes are logarithms of pressure. However, in the figure for Itazuke in Kezia, the distances from the typhoon center are taken an abscissa. As, in a system such as the typhoon , the relation between time intervals of observations and distances from the center is not linear , and as the typhoon rapidly fills after landing, so that utility of time isopleths is limited within some degrees. However, from the common characters of time isopleths, characteristic vertical pressure distributions in the typhoon system are understood in some details. Space cross-section of pressure and temperature Figs. 10 (a and b) Time isopleths of pressure and temperature anomalies for Nazi ma (a), Yonago (b). In these figures, solid lines represent pressure anomalies or each 40 dyn. m. , dotted lines temperature anomalies for each 2°C, II and L relatively high and low pressure areas, and IV and C relatively warmer and colder areas. Figs. ii (a and b) Time isopleths of pressure and temperature anotnalies for Itazuke (a), Kagoshiina(b). The explanation of represent- ation are same as Figs. 10. distributions taken NE to SE through the center of Kezia near Itazuke .iE shown in Fig.

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