Late Holocene changes in precipitation in northwest Tasmania and their potential links to shifts in the Southern Hemisphere westerly winds

Saunders, Krystyna M.; Kamenik, Christian; Hodgson, Dominic A.; Hunziker, Stefan; Siffert, Luca; Fischer, Daniela; Fujak, Marian; Gibson, John A.E.; Grosjean, Martín

doi:10.1016/j.gloplacha.2012.04.005

Cited by 37 publications

(24 citation statements)

References 58 publications

(80 reference statements)

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“…Wind reconstructions from South Africa are roughly consistent with the timing and direction of changes observed in the eastern Pacific during the past millennium (Stager et al, 2012), while records from Australia and New Zealand are neither consistently in-phase nor out (Knudson et al, 2011;Saunders et al, 2012). Knudson et al (2011) suggested that in addition to potential changes in the extent and intensity of the SWW belt, the SWW varied zonally, likely due to interactions with atmospheric pressure systems, which shift in response to changes in high-frequency climate oscillations such as the SAM and ENSO.…”

Section: (B)supporting

confidence: 52%

Centennial-scale variability of the Southern Hemisphere westerly wind belt in the eastern Pacific over the past two millennia

et al. 2014

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Abstract. We present the first high-resolution (sub-annual) dust particle data set from West Antarctica, developed from the West Antarctic Ice Sheet (WAIS) Divide deep ice core (79.468 • S, 112.086 • W), and use it to reconstruct changes in atmospheric circulation over the past 2400 years. We find a background dust flux of ∼ 4 mg m −2 year −1 and a mode particle size of 5-8 µm diameter. Through comparing the WAIS Divide record with other Antarctic ice core particle records, we observe that coastal and lower-elevation sites have higher dust fluxes and coarser particle size distributions (PSDs) than sites on the East Antarctic plateau, suggesting input from local dust sources at these lower-elevation sites. In order to explore the use of the WAIS Divide dust PSD as a proxy for past atmospheric circulation, we make quantitative comparisons between both mid-latitude zonal wind speed and West Antarctic meridional wind speed and the dust size record, finding significant positive interannual relationships. We find that the dust PSD is related to midlatitude zonal wind speed via cyclonic activity in the Amundsen Sea region. Using our PSD record, and through comparison with spatially distributed climate reconstructions from the Southern Hemisphere (SH) middle and high latitudes, we infer that the SH westerlies occupied a more southerly position from circa 1050 to 1400 CE (Common Era), coinciding with the Medieval Climate Anomaly (MCA). Subsequently, at ca. 1430 CE, the wind belt shifted equatorward, where it remained until the mid-to-late twentieth century. We find covariability between reconstructions of El Niño-Southern Oscillation (ENSO) and the mid-latitude westerly winds in the eastern Pacific, suggesting that centennial-scale circulation changes in this region are strongly influenced by the tropical Pacific. Further, we observe increased coarse particle deposition over the past 50 years, consistent with observations that the SH westerlies have been shifting southward and intensifying in recent decades.

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Section: (B)supporting

confidence: 52%

Centennial-scale variability of the Southern Hemisphere westerly wind belt in the eastern Pacific over the past two millennia

et al. 2014

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“…This opens the door to the analysis of sub-varve scale of NPP. That is clearly an advantage compared with reflectance spectra from point measurements with typical 2-8 mm spatial resolution (Rein and Sirocko 2002;von Gunten et al 2009;von Gunten et al 2012;Saunders et al 2012;Amann et al 2014;Michelutti and Smol 2016).…”

Section: Combination Of Hplc-and Hsi-inferred Pigment Concentrationsmentioning

confidence: 99%

“…The analysis of sedimentary pigments (typically with HPLC) is, however, challenging and high-resolution long records are difficult to obtain. Recently, important advancements have been made with non-destructive scanning reflectance spectroscopic techniques which facilitated the measurement of lutein, chlorophylls and their derivates (chlorins) directly from fresh sediment cores at mm-scale resolution (Rein and Sirocko 2002;Rein et al 2005;von Gunten et al 2009;Saunders et al 2012;Amann et al 2014). Butz et al (2015) and Butz et al (2017) developed this approach further and used spectra from a scanning hyperspectral imaging system (HSI; pixel size: ~68 x 68 µm; spectral resolutions ~2.7 nm) to infer 'green pigments' {chlorophyll a and pheophytin a} as well as bacteriopheophytin a at subvarve-scale resolution.…”

Section: Introductionmentioning

confidence: 99%

A high-resolution pigment and productivity record from the varved Ponte Tresa basin (Lake Lugano, Switzerland) since 1919: insight from an approach that combines hyperspectral imaging and high-performance liquid chromatography

et al. 2018

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A high-resolution pigment and productivity record from the varved Ponte Tresa basin (Lake Lugano, Switzerland) since 1919: insight from an approach that combines hyperspectral imaging and high-performance liquid chromatography A high-resolution pigment and productivity record from the varved Ponte Tresa basin (Lake Lugano, Switzerland) since 1919: insight from an approach that combines hyperspectral imaging and high-performance liquid chromatography Abstract Eutrophication, prompted by anthropogenic activities and climate change has led to multiple adverse effects in freshwater systems across the world. As instrumental measurements are typically short, lake sediment proxies of aquatic primary productivity (PP) are often used to extend the observational record of eutrophication back in time. Sedimentary pigments provide specific information on PP and major algal communities, but the records are often limited in the temporal resolution. Hyperspectral imaging (HSI) data, in contrast, provide very high seasonal (sub-varve-scale) resolution, but the pigment speciation is limited. Here, we explore a combined approach on varved sediments from the Ponte Tresa basin, southern Switzerland, taking the advantages of both methods (HSI and high performance liquid chromatography, HPLC) with the goal to reconstruct the recent eutrophication history at seasonal to interannual resolution. We propose a modified scheme for the calibration of HSI data (here: Relative Absorption Band Depth between 590 and 730 nm RABD590-730) and HPLC-inferred pigment concentrations (here: 'green pigments' {chlorophyll a and pheophytin a}) and present a calibration model (R 2 = 0.82; RMSEP ~ 12%). The calibration range covers >98% of the spectral index values of all individual pixels (68 µm x 68 µm) in the sediment core. This allows us to identify and quantify extreme pigment concentrations related to individual major algal blooms, to identify multiple algal blooms within one season, and to assess interannual variability of PP. Prior to the 1930s, 'green pigment' concentrations and fluxes (~50 µg g -1 ; ~2 µg cm -2 a -1 , chlorophyll a and pheophytin a) and interannual variability was very low. From the 1930s to 1964, chlorophyll a and pheophytin a increased by a factor of ~4, and ββ-carotene appeared in substantial amounts (~0.4 µg cm -2 a -1 ). Interannual variability increased markedly and a first strong algal bloom with 'green pigment' concentrations as high as 700 µg g -1 is observed in 1958. Peak eutrophication (~12 µg cm -2 a -1 chlorophyll a and pheophytin a) and very high interannual variability with extreme algal blooms ('green pigment' concentrations up to 1400 µg g -1 ) is observed until ca. 1990, when eutrophication decreases slightly. Maximum PP values after 2009 are likely the result of internal nutrient cycling related to repeated deep mixing of the lake.

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“…Palaeoclimate records of wind strength reconstruct changes in atmospheric circulation using the strong positive correlation between wind strength and precipitation in the middle latitudes of the Southern Hemisphere (Garreaud, 2007). Although there are a number of records from southern New Zealand (Gellatly et al, 1988;Knudson et al, 2011;Lorrey et al, 2008Lorrey et al, , 2014Putnam et al, 2010;Turney et al, 2017), Tasmania (Saunders et al, 2012), and southern South America (Aracena et al, 2015;Ariztegui et al, 2010;Lamy et al, 2001Lamy et al, , 2010Moreno et al, 2009Moreno et al, , 2014Moy et al, 2008Moy et al, , 2009Schmipf et al, 2011;Turney et al, 2016a;Waldmann et al, 2010;and others), there are fewer from the subantarctic islands, all of which have a palaeovegetation focus (McFadgen and Yaldwyn, 1984;McGlone 2002;McGlone et al, 2000McGlone et al, , 2010McGlone and Moar, 1997;Turney et al, 2016b).…”

Section: Introductionmentioning

confidence: 99%

Late Holocene intensification of the westerly winds at the subantarctic Auckland Islands (51° S), New Zealand

et al. 2017

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Abstract. The Southern Hemisphere westerly winds (SHWWs) play a major role in controlling wind-driven upwelling of Circumpolar Deep Water (CDW) and outgassing of CO 2 in the Southern Ocean, on interannual to glacial-interglacial timescales. Despite their significance in the global carbon cycle, our understanding of millennialand centennial-scale changes in the strength and latitudinal position of the westerlies during the Holocene (especially since 5000 yr BP) is limited by a scarcity of palaeoclimate records from comparable latitudes. Here, we reconstruct middle to late Holocene SHWW variability using a fjord sediment core collected from the subantarctic Auckland Islands (51 • S, 166 • E), located in the modern centre of the westerly wind belt. Changes in drainage basin response to variability in the strength of the SHWW at this latitude are interpreted from downcore variations in magnetic susceptibility (MS) and bulk organic δ 13 C and atomic C / N, which monitor influxes of lithogenous and terrestrial vs. marine organic matter, respectively. The fjord water column response to SHWW variability is evaluated using benthic foraminifer δ 18 O and δ 13 C, both of which are influenced by the isotopic composition of shelf water masses entering the fjord. Using these data, we provide marine and terrestrial-based evidence for increased wind strength from ∼ 1600 to 900 yr BP at subantarctic latitudes that is broadly consistent with previous studies of climate-driven vegetation change at the Auckland Islands. Comparison with a SHWW reconstruction using similar proxies from Fiordland suggests a northward migration of the SHWW over New Zealand during the first half of the last millennium. Comparison with palaeoclimate and palaeoceanographic records from southern South America and West Antarctica indicates a late Holocene strengthening of the SHWW after ∼ 1600 yr BP that appears to be broadly symmetrical across the Pacific Basin. Contemporaneous increases in SHWW at localities on either side of the Pacific in the late Holocene are likely controlled atmospheric teleconnections between the low and high latitudes, and by variability in the Southern Annular Mode and El Niño-Southern Oscillation.

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Late Holocene changes in precipitation in northwest Tasmania and their potential links to shifts in the Southern Hemisphere westerly winds

Cited by 37 publications

References 58 publications

Centennial-scale variability of the Southern Hemisphere westerly wind belt in the eastern Pacific over the past two millennia

Centennial-scale variability of the Southern Hemisphere westerly wind belt in the eastern Pacific over the past two millennia

A high-resolution pigment and productivity record from the varved Ponte Tresa basin (Lake Lugano, Switzerland) since 1919: insight from an approach that combines hyperspectral imaging and high-performance liquid chromatography

Late Holocene intensification of the westerly winds at the subantarctic Auckland Islands (51° S), New Zealand

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Late Holocene changes in precipitation in northwest Tasmania and their potential links to shifts in the Southern Hemisphere westerly winds

Cited by 37 publications

References 58 publications

Centennial-scale variability of the Southern Hemisphere westerly wind belt in the eastern Pacific over the past two millennia

Centennial-scale variability of the Southern Hemisphere westerly wind belt in the eastern Pacific over the past two millennia

A high-resolution pigment and productivity record from the varved Ponte Tresa basin (Lake Lugano, Switzerland) since 1919: insight from an approach that combines hyperspectral imaging and high-performance liquid chromatography

Late Holocene intensification of the westerly winds at the subantarctic Auckland Islands (51° S), New Zealand

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Late Holocene intensification of the westerly winds at the subantarctic Auckland Islands (51° S), New Zealand