TYPHOON BETH meandered across the South China Sea towards Hong Kong yesterday, causing Royal Observatory forecasters to raise and then lower the No 1 signal. But as the territory waited from noon until dusk, when tropical storm warnings replaced typhoon signals, a local researcher was already working on a better typhoon-tracker. NASA's first space-based measurements of typhoon winds should fine-tune forecasts, said City University associate professor Dr Johnny Chan Chung-leung. Dr Chan, who is involved in the project, said he had supplied data on typhoons Tom and Violet to help NASA test its new 'scatterometer'. The scatterometer - named because it measures wind by analysing how ripples on ocean waves scatter radar signals - will beam regular updates on ocean wind speeds from space. Dr Chan was invited aboard the US-Japan collaboration because of his expertise on typhoons. After seeing the first images from the satellite, he said he would use the data to fine-tune his model. 'It looks very exciting. It really shows what it can do. 'It will be very valuable if it is able to sweep over the typhoon.' Forecasters now use data from ships near typhoons and from satellites, but NASA says the scatterometer's improved resolution should give scientists 100 times more information on ocean winds. The machine, aboard Japan's polar-orbiting Advanced Earth Observing Satellite, picked up images of the typhoons Violet and Tom - each with winds of 95 km/h - in the northwest Pacific on September 20. Days later, Violet rammed into Tokyo and eastern Japan, killing at least seven people and causing hundreds of landslides and extensive flooding. Typhoon Tom blew out over the sea. NASA scatterometer project manager Jim Graf, in California, said the radar could pierce even the gloomiest conditions to relay information predicting hurricanes and winter storms. 'We are very pleased with the quality of these two images,' he said.