A 250-year periodicity in Southern Hemisphere westerly winds over the last 2600 years
Southern Hemisphere westerly airflow has a significant influence on the ocean–atmosphere system of the mid- to high latitudes with potentially global climate implications. Unfortunately, historic observations only extend back to the late 19th century, limiting our understanding of multi-decadal to c...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-02-01
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| Series: | Climate of the Past |
| Online Access: | http://www.clim-past.net/12/189/2016/cp-12-189-2016.pdf |
| Summary: | Southern Hemisphere westerly airflow has a significant influence on the
ocean–atmosphere system of the mid- to high latitudes with potentially global
climate implications. Unfortunately, historic observations only extend back to
the late 19th century, limiting our understanding of multi-decadal to
centennial change. Here we present a highly resolved (30-year) record of past
westerly wind strength from a Falkland Islands peat sequence spanning the
last 2600 years. Situated within the core latitude of Southern Hemisphere
westerly airflow (the so-called <i>furious fifties</i>), we identify highly variable changes in exotic pollen and
charcoal derived from South America which can be used to inform on past
westerly air strength. We find a period of high charcoal content between 2000
and 1000 cal. years BP, associated with increased burning in Patagonia,
most probably as a result of higher temperatures and stronger westerly
airflow. Spectral analysis of the charcoal record identifies a pervasive
ca. 250-year periodicity that is coherent with radiocarbon production rates,
suggesting that solar variability has a modulating influence on Southern
Hemisphere westerly airflow. Our results have important implications for understanding
global climate change through the late Holocene. |
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| ISSN: | 1814-9324 1814-9332 |