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Sea temperature change spawns more typhoons
Publication Date : 18-09-2013
Unusual climate beginning this summer, such as extreme heat, tornadoes and torrential rain, are the effects of global warming, experts have pointed out.
According to the Japan Meteorological Agency, air and sea surface temperatures have both risen due to global warming. Japan’s average air temperature has risen by about 1.15 C over the past 100 years or so. Sea surface temperatures have also continually risen, and five of 10 water areas adjacent to Japan marked a record high in mid-August.
According to the agency’s data, surface temperatures of the Pacific Ocean off western Japan are 28 C to 29 C, one to two degrees higher than usual. A typhoon typically originates in the tropical zone and moves north. When it moves close to Japanese coastal waters, it loses its strength. However, as Typhoon No. 18 entered waters off western Japan, it grew in strength as it moved closer to land and maintained its power for a long time even after making landfall.
There is a correlation between an increase in sea surface temperature and torrential rain and tornadoes. When the air temperature rises, the amount of vapour in the air increases. In addition, when the sea surface heats up, seawater easily evaporates, and the amount of vapour further increases. Warm and humid air generated through such a process develops cumulonimbus clouds, which cause torrential rain and tornadoes.
Starting from around Typhoon No. 18, strong south winds carried large amounts of subtropical air containing vapour to an autumn rain front, which created a storm front. Around the Kinki region, rain clouds from the typhoon and those of the front became integrated, extending the typhoon from north to south covering an area stretching from the Pacific Ocean to the Sea of Japan. Therefore, not only areas near the Pacific, but also areas near the Sea of Japan, along with inland areas of the Kinki region, which were some distance from the typhoon, were hit hard by record-level torrential rains.
“Unprecedented climatic phenomena are expected to continue,” said Takehiko Yamamura, the head of Disaster Prevention System Institute. “It is necessary to pay attention to weather information and protect ourselves.”