Economy

'Respite for Japan from radiation may be temporary'

Vinson Kurian Thiruvananthapuram | Updated on March 18, 2011 Published on March 18, 2011

IMD Run

IMD Run

Weather Underground Run

The respite from exposure to radioactive material emanating from Japan’s quake-ravaged nuclear reactors thanks to favourable sea-ward winds may not last long, according to the latest trajectory model runs by India Meteorological Department (IMD).

The winds are northwesterly-to-westerly over the island nation blowing into the sea but this is likely to be reversed as early as from today (Friday), according to the IMD model runs based on the US National Oceanographic and Atmospheric Administration’s (NOAA) HYSPLIT trajectory model.

WIND DIRECTION

The model uses the GFS (global forecasting system) model's winds to track the movement of a hypothetical release of a substance into the atmosphere.

The Director-General of IMD, Dr Ajit Tyagi, informed Business Line last (Thursday) night that the winds will change to southwesterly, which would make them blow back to the stricken northeast region of Japan.

Weather Underground, a leading private forecaster, is also largely in agreement with the IMD’s outlook.

An update by Weather Underground, a leading private forecaster based in the US, at 7 p.m. IST on Thursday said that favourable winds blowing at 10 - 20 mph out of the northwest continued over Tokyo today, and these winds will take radiation particles emitted by the stricken Fukushima nuclear plant immediately out to sea.

The northwesterly winds are blowing in response to the clockwise flow of air around a high pressure system approaching Japan from the southwest.

Since high pressure systems are regions of sinking air, the radiation will stay close to the ocean surface over the next day or two as the air spirals clockwise over the Pacific.

FIVE-DAY FORECAST

Five-day forecast movement of plumes of radioactive air emitted at 10 meters altitude and 300 meters early Friday morning IST from the Fukushima Daiichi nuclear plant showed plumes initially spiralling clockwise around the high pressure system to the southwest of Japan and staying near the surface.

By Saturday, though, the plumes get caught in a southwesterly flow of air in advance of an approaching low pressure system. Ascending air lifts the plumes to high altitudes, where winds are stronger and rapid long-range transport occurs.

Five-day forecast movement of plumes of radioactive air emitted at 10 meters altitude and 300 meters early Saturday morning shows plumes getting caught in a southwesterly flow of air in advance of an approaching low pressure system.

The plume emitted near the surface would stay trapped near the surface for four days before being lifted to two km. But the plume emitted at 300 meters is lifted to five km altitude after two-and-a-half days by the rising air associated with the approaching low pressure system.

Published on March 18, 2011
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