BEIJING, April 17 (Xinhua) -- The following is a summary of published science and technology news of China.

SATELLITES UPGRADE

China has completed an upgrade of the ground system for its first-generation relay satellite, Tianlian I, according to the Beijing Space Information Transmission Center on Friday.

The upgrade enables the country to operate its two generations of relay satellite systems, Tianlian I and Tianlian II-1, in an integrated manner, said the center.

It also greatly enhances the reliability of the relay satellite systems, as well as their maintainable and automatic natures.

The relay satellite systems will further support the country in improving its tracking, telemetry and control capacity, and they will have roles in the country's upcoming space station mission, according to the center.

GREENHOUSE GAS

Chinese researchers have discovered that greenhouse gases and anthropogenic aerosols induced rainfall reduction in northern Central Asia.

The subtropical westerly jet is one of the important circulation systems in Eurasia and is closely linked to summer precipitation over northern Central Asia at different time scales.

The observed changes in the subtropical westerly jet are attributable to the combined contributions of greenhouse gases and anthropogenic aerosols, according to the recent research article in the journal Geophysical Research Letters.

DRIVERLESS TRAIN

Southwest China's Chongqing Municipality put its first driverless rail transit system, BYD SkyShuttle, into operation in Bishan District on Friday, according to local authorities.

Developed by China's leading new energy vehicle manufacturer BYD, the rail transit system involves electricity-powered, autonomous trains running on a 15.4 km elevated rail line. There are 15 stations along the route.

The vehicles are able to make turns at a minimum radius of 15 meters, and can carry 6,000 to 10,000 passengers per hour at a maximum speed of 80 km per hour.