Flooding and landslides in East Africa have killed dozens of people and forced hundreds of thousands from their homes. Meanwhile, thousands of miles away in Australia, a period of hot, dry weather has led to a spate of bushfires.

Both weather events have been linked to higher-than-usual temperature differences between the two sides of the Indian Ocean - something meteorologists refer to as the Indian Ocean Dipole.

The Indian Ocean Dipole - often called the "Indian Niño" because of its similarity to its Pacific equivalent - refers to the difference in sea-surface temperatures in opposite parts of the Indian Ocean.

Temperatures in the eastern part of the ocean oscillate between warm and cold compared with the western part, cycling through phases referred to as "positive", "neutral" and "negative".

The dipole's positive phase this year - the strongest for six decades - means warmer sea temperatures in the western Indian Ocean region, with the opposite in the east.

The result of this unusually strong positive dipole this year has been higher-than-average rainfall and floods in eastern Africa and droughts in south-east Asia and Australia.