Scientific research shows tiny particles from the Chinese and Mongolian deserts reflect the sun's heat, keeping the Earth cool.

As haru-ichiban, the first wind gusts of the year, are considered a harbinger of spring, so too, is the arrival of windblown sand from deserts in China and Mongolia. Every year, tons of the stuff blanket western Japan, adding to respiratory problems and other health woes, not to mention the tedious job of wiping surfaces clean.

In a word, the annual phenomenon is annoying.

But now, a joint Japan-China research team says there is a beneficial spin-off: These fine particles of sand, more like dust really, might actually help cool the atmosphere.

From March to May, a huge volume of yellow sand is whipped up in the Taklimakan and Gobi deserts, riding westerly winds to sweep down on prefectures bordering the Sea of Japan.

Even 3,776-meter Mount Fuji with its pristine white cap, can look rather dusty at this time of year.

At 113 locations nationwide, a record 1,207 yellow-sand days were recorded in 2002. Sometimes the haze was so bad that airline flights had to be canceled.

Now, specialists have discovered that the gritty particles not only blanket the skies over Japan, but blow far across the Pacific Ocean to North America. But that is not necessarily a bad thing. Experts say the airborne sand is actually playing an active role in curbing global warming by reflecting sunlight.

The Meteorological Research Institute based in Tsukuba, Ibaraki Prefecture, and the Chinese Academy of Science in Beijing began to jointly research the effects of yellow sand on the atmosphere and the environment in fiscal 2000 by analyzing the mechanism of how yellow sand originates and is dispersed.

Data for the 28-year period from 1974 to 2001 showed that fine sand particles rode westerly winds reaching North America. The particles demonstrated a cooling effect over a wide range of atmosphere in the Northern Hemisphere.

Calculated on a global scale, yellow sand particles quell about 0.3 watt of heat per square meter. Carbon-dioxide, one of the main culprits in global warming, is said to produce 1.5 watts of heat per square meter.

The cooling effect was stronger around Japan, with 1 to 5 watts per square meter of heat being dissipated.

According to the Japan Meteorological Agency, each sand particle measures about 0.1 to 10 micrometers. (A micrometer is one-thousandth of a millimeter)

Yellow sand particles possess dual characteristics-they can either repel sunlight and thus act as coolants, or absorb it and heat the atmosphere. The size of the particles is the deciding factor.

Scientists suspect the yellow-sand particles create hazy clouds that act as a giant parasol, or a sun screen, further promoting a cooling effect.

``Now, we want to find out what kind of role the yellow sand plays in creating clouds, and how those clouds affect the climate,'' said Masao Mikami, a research specialist at the Meteorological Research Institute.(IHT/Asahi: February 10,2005)