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Typhoon Rita was one of the longest-lived Western Pacific tropical cyclone on record, traversing the basin along an erratic path for 22 days. The second of four simultaneously developing storms, Rita was first identified to the southeast of Guam on July 5, 1972. ==Meteorological history== In early July 1972, conditions across the western Pacific were highly favorable for tropical cyclogenesis. Enhanced by an El Niño event, surface westerlies traversed the region south of an east-west near-equatorial trough that extended from east of the Philippines to well east of the Marshall Islands. On July 3, conditions in the upper troposphere over the basin underwent significant changes with two upper-level troughs developing in the midlatitudes; of note was one which moved southward from Japan. By July 5, four distinct disturbances had organized along the near-equatorial trough; however, limited data made further analysis on these systems difficult. The precursor to Rita specifically was situated to the southeast of Guam at this time. The Japan Meteorological Agency (JMA) classified the system as a tropical depression at 12:00 UTC that day. On July 6, the precursor depression to Rita was invigorated as it interacted with a cutoff low to its north. Simultaneously, a subtropical ridge rapidly built on either side of the cutoff low. Within a complex upper-level environment, favorable outflow was able to form over the system and enhance convective development.〔 It was estimated that the depression attained tropical storm-status by 00:00 UTC on July 7 while located south of Guam. Moving west and later northwest, the storm steadily intensified to typhoon status by 12:00 UTC the following day. Increasingly vigorous outflow, attributed to the cutoff low near Japan, enabled continued deepening of the cyclone over the next two days.〔 Rita ultimately attained its peak intensity on July 11 as a Category 5-equivalent typhoon on the modern-day Saffir–Simpson hurricane wind scale with sustained winds of 270 km/h (165 mph) and a barometric pressure of 911 mbar (hPa; 26.90 inHg). At this time, the storm displayed a well-defined 37 km (23 mi) diameter eye〔 At its peak, Rita was a somewhat lopsided system, with deep convection and cirrus clouds extending more to the northwest than any other quadrant. Following the typhoon's peak intensity, the cutoff low previously providing Rita with favorable outflow rapidly weakened. This resulted in a near-total collapse of outflow along the storm's northern side and prompted dramatic weakening.〔 Simultaneously, the cyclone turned more westerly and slowed as an intensifying Typhoon Phyllis to its east began to influence Rita.〔 Convection along the north side of the typhoon contracted significantly, with Rita's eye situated close to the edge of the convective canopy on July 12. In contrast to the weakening on the north side, outflow along the south side of Rita became more pronounced.〔 By July 13, Rita had briefly stalled and began moving to northeast owing to a process known as the Fujiwhara effect.〔 The once Category 5 system had degraded to minimal typhoon status by July 14.〔 On July 14 and 15, Rita again stalled as Typhoon Phyllis swung around to the north and headed to Japan.〔 The storm re-intensified slightly during this period with winds reaching 160 km/h (100 mph) and its pressure dipping to 962 mbar (hPa; 28.41 inHg).〔 This re-invigoration was short-lived as Rita weakened soon thereafter and began moving slowly to the north-northwest.〔 The typhoon maintained its intensity for two days until a new outflow channel established itself over the storm. This channel, previously aiding the development of Typhoon Tess to the west, enabled Rita to attain winds of 175 km/h (110 mph) on July 18.〔〔 Alongside the increase in winds was a dramatic increase in the storm's size; by July 18 gale-force winds spanned an area approximately 1,290 km (800 mi) across. Another major shift in the typhoon's course took place that day as a ridge build over the Sea of Japan and imparted a more westerly track.〔 Weakening slightly once more Rita passed through the Ryukyu Islands of Japan on July 20, with its center passing just north of Amami Ōshima; a pressure of 968.9 mb (hPa; 28.61 inHg) was measured there. Typhoon-force winds were measured 150 km (90 mi) north of the center at this time on Gajajima. Upon moving over the East China Sea on July 21, an unusual set of conditions prompted Rita to turn southwest. The two main factors in this were the presence of a low over Manchuria which resulted in slower forward movement and Typhoon Tess located 1,480 km (920 mi) east which pulled the storm south due to the Fujiwhara effect. Over the following three and a half days, the typhoon looped along the edge of the Ryukyu Islands, fluctuating in strength all the while.〔 The center of Rita brushed Miyako-jima as a Category 1-equivalent typhoon on July 23 and Okinawa as Category 2-equivalent the following day.〔 Rita completed its cyclonic loop on July 25 and subsequently accelerated northward as it moved into a convergent flow region between the Manchuria low and the ridge near Japan. The storm skirted the Korean Peninsula on July 26, passing near Jeju Province off the southwestern coast of South Korea, before moving over the Yellow Sea. Turning westward over the Sea, Rita brushed the northern coast of Shandong Peninsula in China before transitioning into an extratropical cyclone over the Bohai Sea around 12:00 UTC on July 26 according to the JMA's best track.〔 Thereafter, the storm's winds dropped below typhoon force for the first time since it attained such winds 18 days prior. Rita then made landfall near Tianjin, China as a weakening system.〔 Though judged to be extratropical by the JMA at this time, the China Meteorological Agency asserts that Rita remained tropical until its landfall in accordance with radar imagery and radiosonde observations.〔中央气象局研究所 ．一九七三年气象雷达会议文集 . 1973 . p. 51-59 ．〕 Regardless of the true nature of the system as it struck North China, Rita further degraded over land. The remnant low persisted for several more days as they moved through Northern China and eventually Mongolia by July 28. The remnants of Rita were last noted on July 30 as a 1000 mb (hPa; 29.53 inHg) low over Northeast China.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Typhoon Rita (1972)」の詳細全文を読む スポンサード リンク
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