An Australian oceanographer is hopeful that scientists can calculate the presumed crash site of Malaysia Airlines flight MH370 to within 10,000 square km in the southern Indian Ocean.

Erik van Sebille, of the University of New South Wales in Sydney, said groups of scientists around the world were ready and waiting for searchers to find some confirmed wreckage from the aircraft so they could start tracing back the currents to a possible crash site.

He said he had been in contact with fellow oceanographers in the United Kingdom, the United States, Australia and Germany, who were preparing drift modeling that would help corroborate satellite evidence of a crash announced earlier this week.

But the longer they waited the more difficult the task became.

"The thing is that because it's been such a long time that the debris has been in the water already, it goes beyond our technical capabilities to get a very exact backwards trajectory," van Sebille told Xinhua in an interview Thursday.

"It's a bit like forecasting the weather. Because the weather is so chaotic, you can forecast it for say seven days, but you can 't say what the weather in Beijing is going to be in five weeks.

"The same is true for the ocean. The ocean essentially loses its memory. We can't trace it back to more than a few days and the longer we have to trace it back, the larger our uncertainty's going to be and the larger the area's going to be where this debris was back on the edge of March.

"We need to be very careful that the winds and the currents are not in exactly the same direction, so it very much depends how far a piece of debris sits above the water, how much wind there is versus how strong the current is."

Essentially every piece of debris would take a completely different trajectory depending on where it fell in the ocean and how far it sits above the water and how buoyant it is, he said, adding, "That's why this situation is very difficult."

Van Sebille said he had done his own rough and incomplete estimation of a crash site where the black box flight data and cockpit voice recorders might be found.

"We should be able to get an area within say 10,000 square km or so, which is huge of course, but it's much smaller than what they're searching now. I think if you then combine that with the satellite ping information from the Inmarsat information from a few days ago, I would really like to hope that we do solve this," he said.

A massive international research program, begun in the 1980s, had seen the release of tens of thousands of buoys with GPS and satellite signaling, providing scientists with a "good theory" of how the ocean currents moved, but the southern Indian Ocean was full of eddies that made the currents less predictable in the short term.

"The ocean down there is so turbulent and so chaotic that actually, if the plane had hit the water in a spot 100 km away, it might have drifted completely differently," said van Sebille.

If the debris were in the current search area, a total area of 80,000 square km about 2,500 km from the southwestern city of Perth, it might wash up on shores in South Australia or Tasmania " within half a year or a year or so."

Working aboard a ship in the southern Indian Ocean was difficult enough in the summer when the conditions were the best.

"It's very difficult and very tiring to work in these conditions and now it gets only worse as we get into autumn and soon into winter. The winds are going to really pick up and they' re going to be bigger and bigger and bigger and the waves are going to be higher and higher and higher."?