El Nino found to affect typhoons

Japanese researchers said Tuesday that the El Nino effect strengthens typhoons and thus increases typhoon-related damage in Japan.

The findings of a joint study by Ryuzaburo Yamamoto, professor emeritus at Kyoto University, and the Japan Weather Association will be presented at the annual meeting of the Meteorological Society of Japan, which begins today, the researchers said.

A study of typhoons between 1951 and 1999 shows that typhoons are stronger when the El Nino effect — which warms sea temperatures in the Pacific Ocean off Peru — is present.

They said El Nino storms form further to the east in the Pacific and strengthen as they travel for a relatively long period over waters with high temperatures before approaching the Japanese archipelago.

Damage from typhoons forming in El Nino years is three times higher than in years experiencing the La Nina phenomenon, in which the temperature of the sea surface off Peru drops.

The researchers said the average number of typhoons in years in which the El Nino phenomenon was present was 16.1, slightly less than the average 18.2 in years of La Nina.

However, the average atmospheric pressure at the center of the typhoons when they were at their most developed was 953.6 hectopascals in the years of El Nino and 964.5 hectopascals in the years of La Nina.

The average number of days in which the typhoons maintained strength under 970 hectopascals was 46.3 days for the El Nino years and 26.9 days for La Nina years.

The average radius of the storm area was 235.9 km for El Nino years and 180.4 km for La Nina years.

The total cost of damage from 15 typhoons in El Nino years since 1970 was about 1.7 trillion yen, while that for 11 typhoons in La Nina years was about 560 billion yen.

The El Nino phenomenon brings abnormal weather such as droughts and floods to Pacific Rim countries.