Features of some interacting tropical cyclones in the Indian Ocean after the Mount Pinatubo eruption
Abstract
The features of the impact of some tropical cyclones (TC) in the Indian Ocean on the environment after the eruption of Mount Pinatubo are considered. The 1992 North Indian Ocean cyclone season was unofficially the most active year on record for the basin, with 13 TC developing. It was shown that TC-05B, closing the chain of 10 TC before its destruction over the North Bay of Bengal, showed anomalous thunderstorm activity and contributed to the emergence of TC Aviona in South Indian Ocean. The strongest in season-92 TC-10B and TC Forrest, apparently, caused an earthquake in the Indian Ocean. At the same time, the strongest typhoons Hunt and Gay from 1979 to 2015 simultaneously developing in the Pacific Ocean caused the Burma Plate earthquake. Experimental data of anomalous features of the ionosphere during these events were obtained using the satellite Cosmos-1809.
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Introduction
The problem of the movement of several interacting tropical cyclones and their impact on the environment is complex. It was previously shown that two tropical cyclones, at a distance of less than 1,400 km from one another, begin to rotate around a common center and converge [1]. Currently, meteorology typically uses a modified ETA model: North American Mesoscale Forecast System (NAM) [2] or Weather Research and Forecast Model (WAR) [3] to predict the development of tropical cyclones. Manipulating the vast datasets and performing the complex calculations necessary to modern numerical weather prediction requires some of the most powerful supercomputers in the world. Examples of such calculations and detailed references are presented in the series of works by the authors [4].
Further studies showed that the nonlinear dynamics of internal gravity wave (IGW) structures of the dissipative ionosphere in the presence of a heterogeneous zonal wind can create both monopole vortices in the form of a tropical cyclone and a vortex path along the zonal wind [5, 6]. IGW can occur both in multiple lightning discharges and in the structures of a developed tropical cyclone [7-9]. The flow of atmospheric air over obstacles such as islands or isolated mountains sometimes gives birth to von Karman vortex streets [10]. The significant role of the structure of the lower stratosphere in the development of a tropical cyclone was noted in [11] and in separate sections of the annual reports of the Joint Typhoon Warning Center (JTWC) by J.C. Sadler. The structure of the equatorial stratosphere is associated with the development phase of the quasibiennial oscillation (QBO) [12, 13].
Analysis conducted by the authors according to the Cosmos-1809 satellite showed that a month after the eruption of Mount Pinatubo 12-Jun-91 [14], the plasma density of the upper ionosphere near the equator decreased approximately two times, and a continuous sequence of typhoons was observed in the western Pacific [15, 16].
In 1992, the cyclonic activity of the world's oceans, characterized by the Accumulated Cyclone Energy (ACE) index, increased by 50% [15]. TCs achieved the highest activity in September-November 92, when up to 10 TCs simultaneously developed. At this time the eastern phase of QBO was observed in the lower stratosphere [12]. IGW acoustic effects from numerous strong aftershocks of the Landers-92 earthquake and from underground nuclear tests (UNT) on the Nevada Test Site (NTS) on the atmosphere contributed to the development of a chain of interacting TCs in accordance with the theoretical conclusions of Aburjania [16-18].
One of the authors' research results was the detection of the dependence of the earthquake occurrence during the intensification of TCs of the fifth category: Andrew (August), Bonnie and Charley (September) in the Atlantic Ocean, and Gay and Hunt (November) in the Pacific Ocean. Earthquakes occurred on the southern border of the American Plate in the South Sandwich Islands on August 24 (M = 6.1), September 24 (M = 5.5 and 5.6) and November 21 (M = 6.6) (Table 1). A possible mechanism for the occurrence of earthquakes is associated with the raising of tectonic plates in the zone of the “eye” of TC and lowering the opposite edge of the plate, what is suggested in the presentation of the report [18].
Conclusion
1. After the Pinatubo eruption, TC enhancement in the Indian Ocean correlated with the development of Pacific typhoons was observed with an east wind in the lower stratosphere.
2. The earthquakes in Simeulue, Indonesia were caused by the joint intensification of TCs into the Bay of Bengal and into South China Sea on November 02 and 13.
3. Earthquakes in Nicobar Islands, India region occurred after August 4, Super Hurricanes Janis and November 22 Gay crossed Marinas Trench and entered the Philippine Sea. Earthquakes in this area also occurred after intensification of the global TCs chain September 24 and intensification of TCs in the South Pacific Ocean and South Indian Ocean December 8, 10 and 27.
4. The earthquake in Indian Ocean Triple Junction November 15 occurred after the synchronous amplification of TC 10B into the Arabian Sea and Forrest into the Andaman Sea. According to the Centennial Earthquake Catalog, it was the only earthquake with Mw>2.5 in the region during the period of November 11-22. It is assumed that it was associated with the rise of the Indian Plate in the zone of development of two TC and the lowering of the edge of the Indian Plate in a node with two adjacent plates.
5. Probably December 25, 2004, the intense tropical cyclone Chambo to 80 kt (150 km / h) in central South Indian Ocean lifted the southern edge of the Indian Plate. The eastern edge of the Indian Plate plummeted beneath the Burma Plate, the mega earthquake of 9.1 Mw and the Boxing Day Tsunami occurred. This situation requires further detailed consideration and refinement of the forecast of such events [24].