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BCCR Seminar:3-dimensional insights on the climatology of midlatitude cyclones in the Southern Hemisphere.”

Time

23. June 2025, 09:00-10:00

Location

BCCR lecture room 4020, Jahnebakken 5

Next week’s BCCR Monday seminar will be given by Nicholas Grosfeld, who is visiting BCCR from the University of New South Wales, ARC Center of Excellence for 21st Century Weather in Australia. He will present his work on "3-dimensional insights on the climatology of midlatitude cyclones in the Southern Hemisphere.”. The seminar will take place in the usual BCCR seminar room (4th floor of the West wing) at 11:00.

Abstract

Synoptic cyclones are known to make important contributions to rainfall across the Southern Hemisphere landmasses. In Southern Australia, these lows underpin a key component of interannual rainfall variability, and can occasionally lead to flooding. Countless studies have employed automated identification and tracking schemes to reveal insights to these weather systems based on analysis at a single level of the troposphere, while more recent works have begun to extend the tracking process across several levels.
In this talk I will first describe a simple algorithm to identify and track synoptic cyclones throughout the depth of the troposphere, which will be applied to geopotential height data in the ERA5 reanalysis, across the whole Southern Hemisphere, for the years 1979-2022. These cyclones will then be classified according to whether the system first develops in the lower, middle, or upper troposphere, and differences in the climatology of these classes of cyclones will be presented. Finally, the contribution of each of these classes of cyclones to annual rainfall across Southern Australia will be explored.

Speaker information

After completing high-school in rural Australia during the Millennium Drought, Nicholas completed a bachelor of science, majoring in Atmosphere and Ocean science, at the University of Melbourne, and then an honours year at UNSW. Nick’s research interest lies at the intersection of synoptic meteorology and climate dynamics, and improving the prediction of rainfall. Nick is continuing his research on the nature and variability of rain-bearing cyclones across the Southern Hemisphere mid-latitudes in a PhD at UNSW.

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12.06.25

BCCR Seminar by Michael Bird: "Heinrich Events in the Antipodes?"

Dear all, This week’s BCCR seminar will be given on Thursday, June 12th by Michael Bird, who is visiting BCCR from James Cook University in Australia. He will present his work on "Heinrich Events in the Antipodes”. Abstract Heinrich events are major reorganisations of global ocean circulation that originate in the North Atlantic in response to the melting of icecaps on the adjacent land masses. They are known to drive ‘weak monsoon events’ in China, which is at the northern end of the coupled East Asian and Indo-Australian Monsoon domain. There is currently no record of the impact of Heinrich events in the Australian region. This talk will first provide an insight into the realities of fieldwork in the seasonally dry north Australian savanna region. It will then present a record of pollen, organic carbon and the hydrogen isotope composition on n-alkanes in an 18-metre sedimentary record from a permanently wet sinkhole lagoon in the Northern Territory of Australia. Radiocarbon and OSL dating of the sediments indicates the core provides a continuous 150,000-year record of fire regime, vegetation and climate. Interpretation is complicated by the fact that coastline position near the site changes by ~320 km from interglacial to full glacial conditions as a result of sea level change and a wide flat continental shelf. However, most Heinrich events are evident in the record as short, rapid increases in tree pollen representation and decreases in the hydrogen isotope composition of terrestrially sourced n-alkanes. These trends are both consistent with monsoon intensification in the Indo-Australian Monsoon domain accompanying Heinrich events. Speaker information Michael Bird trained as a geologist, obtaining a PhD in isotope geochemistry in 1988 from the Australian National University. Following a postdoctoral fellowship at the University of Western Ontario (Canada), he returned to Australia as Research Fellow, Queen Elizabeth II Fellow and Fellow at the ANU. In 2000 he moved to an Associate Professorship in Singapore then to the Chair in Environmental Change at the University of St. Andrews (Scotland) in 2004. He returned to Australia in 2009 to take up an Australian Research Council Federation, then Laureate, Fellowship. He is currently a Distinguished Professor at James Cook University. His research interests include the carbon cycle, geoarchaeology and environmental change in the tropics.

13.06.25

Bjerknes choir’s summer concert

Bjerknes choir’s summer concert will take place at 1.30pm on Friday 13th June, in the front entrance hall of the Geophysical Institute. We would like to invite you all to join us for a celebration of song and summer!