Two meteorologists warned that the Beijing would encounter a
possibly high frequency of lightning during the Olympic season next
summer and protection should be made in those particularly
vulnerable areas.
In an academic paper submitted Thursday to the ongoing 13th
International Conference on Atmospheric Electricity, Guo Hu, head
of the Beijing Meteorological Observatory (BMO), and his fellow
researcher Xiong Yajun concluded, after studying the 11-year
lightning disaster data from 1995 to 2005, that Haidian District
was the area most seriously affected by lightning disasters.
Haidian was among the high-frequency region of natural lightning
while lots of universities, research institutes, tall buildings and
electric equipment were based there, they said.
Most of the 31 Beijing Olympic venues are located in Haidian and
some are open-aired.
The statistics showed that the lightning disaster frequency in
Haidian is 4.73 times every year, which was followed by Fengtai,
Chaoyang and Tongzhou at 2.5 times a year, Guo and Xiong said in
the paper.
An electric current, lightning is a bright flash of electricity
produced by a thunderstorm. All thunderstorms produce lightning and
are dangerous. Within a thundercloud way up in the sky, many small
bits of frozen raindrops bump into each other as they move around
in the air, which creates electric charges.
The China Meteorological Administration released that lightning
disasters resulted in 12 deaths, 30 injuries and 246 damage reports
from 1997 to 2005 in Beijing.
The meteorologists employed four indexes for evaluating
vulnerability of lightning disaster areas in Beijing. The indexes
include flash density which is from data gathered by
satellite-board lightning imaging sensor (LIS) and optical
transient detector (OTD), historical disaster frequency, economic
vulnerability module and population-related vital vulnerability
module.
Analyzing the vulnerability degrees, the meteorologists
summarized that districts of Dongcheng, Xicheng and Fengtai are the
most vulnerable while Haidian, Chaoyang and Tongzhou districts are
among the second tier of vulnerability.
Compared with other parts in north China, Beijing is more likely
to be hit by thunderstorms and lightning due to its geographical
and meteorological conditions, the experts said.
Historical data showed that the flash density in northeast part
of Pinggu county was as high as 16 times per square kilometers per
year.
The sky over Beijing has been monitored by the country's best
facilities. There are four lightning monitors covering most areas
of Hebei Province, which is adjacent to Beijing.
A Doppler radar takes the mission of scanning 300 square kilometers
surrounding Beijing. In addition, a satellite surveys most part of
north China, Guo said.
Guo said the prediction and warning system is able to produce
the next 24-hour thunderstorm potential objective forecast and the
next 2-hour thunderstorm warning.
The real-time radar and other parts of the monitoring system
would collect lightning and sounding data, which are automatically
categorized by the BMO neural networks. Meteorologists then use the
dynamic fit for tracking algorithm to analyze the mobile vector of
thunderstorms and, subsequently, forecast areas which would be
possibly affected by the thunderstorms.
The BMO tested its contingency plan for thunderstorm forecast
service around August 8, exactly one year before the opening
ceremony of the 2008 Beijing Olympics. The BMO reported three times
on possible thunderstorms, gales or lightnings to the Olympic
organizing committee. At least six additional observation points
have been built around the Olympic venues for weather
surveillance.
(Xinhua News Agency August 17, 2007)