Australian Drought Research Paper

Topic 1 - Drought

Drought is a phenomenon that has become characterizes a majority of Australia’s climate. It can be detrimental to the population of Australia especially on agricultural productivity. Within the region of drought southeastern Australia there are three main occurrences that cause drought, El Niño Southern oscillation, Indian Ocean dipole and variability and the Southern annular mode. Since drought in Australia can become so severe, the federal government has accepted drought as a feature of the climate and has emergency funding for those affected in times of ‘exceptional circumstances’ (textbook).

With Australia being termed as the driest inhabited continent in the world drought can be broadly defined as a period of time

El Niño southern oscillation involves a cycle that can occur every 2-7 years that changes the pressure gradient within the Indonesian – Australian low-pressure cell and the Southern pacific High pressure cell over the Peruvian coast.

ENSO involves three phases, Neutral, La Nina and El Nino. El Nino and its affects on Australia is the aspect of the oscillation that brings high pressure systems, cooler ocean temperatures and convection moves away from the Australian coast which all generate drought. The Neutral phase is comprised of the normal walker circulation of the atmosphere; trade winds blow westward, this produces warm surface water in the west (Indo-Australia) and cool surface water in the east (Peruvian coast). This normal cell pattern brings strong uplifts of moist air resulting in heavy seasonal rainfall off the Australian coasts. The La Nina phase is like an intensification of the walker circulation where there is increased convection and stronger trade winds over towards Australia resulting in increased

Although when there is less moist air developing over the northern Indian ocean less clouds full of precipitation is moved to southern Australia and victoria greatly impacting the rainfall for the usual time periods over winter and spring.

Just like the ENSO affects the east coast of Australia from the Pacific Ocean, the Indian Ocean dipole affects the western coast leading into southern Australia from the Indian Ocean. This weather pattern varies between positive, neutral and negative phases in a cycle similar to that of ENSO, although at the rate of every 3-8 years. (CSIRO). As mentioned, during these positive IOD events lower moisture developing over the north eastern Indian Ocean is caused by below average sea surface temperatures and similar to ENSO, this cool water causes less convection causing droughts in Australia whilst introducing floods to parts of India and East Africa. It is also believed that positive IOD events have a significant influence on extreme weather events like drought, but also events such as wildfire in southern Victoria specifically the Black Saturday bushfires in Victoria in 2009. During the negative phase, there is a presence of warmer water