Climate summary for the southern hemisphere, 2019–20: a strong positive Indian Ocean Dipole
Blair Trewin
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Abstract
This is a summary of the southern hemisphere atmospheric circulation patterns and meteorological indices for 2019–20; an account of rainfall and temperature for the Australian region is also provided. The second half of 2019 was dominated by a strong positive Indian Ocean Dipole, before a return to more normal conditions from early 2020. The Indian Ocean Dipole, along with generally negative phases of the Southern Annular Mode associated with a marked high-latitude sudden stratospheric warming, contributed to very dry conditions in Australia in the second half of 2019, with exceptional fire weather conditions and associated severe fires. The sudden stratospheric warming was also a major contributor to a well below average Antarctic ozone hole in spring 2019. It was also fairly dry over most other southern hemisphere continental areas, and over the Maritime Continent in the second half of 2019, with the most significant wet anomalies in 2019–20 being in equatorial east Africa. Temperatures were well above average in 2019–20 for both Australia and the southern hemisphere as a whole.
Keywords: 2019, 2020, Black Summer of fire, climate summary, El Niño–Southern Oscillation, ENSO, Forest Fire Danger Index, Indian Ocean Dipole, IOD, OLR, outgoing longwave radiation, Pacific, rainfall anomalies, rainfall overview, SAM, sea ice extent, sea surface temperature, seasonal summary, southern hemisphere, SST, summer of extremes, Southern Annular Mode, temperature anomalies, temperature overview.
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