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

2017 ◽  
Vol 13 (10) ◽  
pp. 1301-1322 ◽  
Author(s):  
Imogen M. Browne ◽  
Christopher M. Moy ◽  
Christina R. Riesselman ◽  
Helen L. Neil ◽  
Lorelei G. Curtin ◽  
...  
Keyword(s):  
New Zealand ◽  
Late Holocene ◽  
Vegetation Change ◽  
Drainage Basin ◽  
Southern Oscillation ◽  
Southern Annular Mode ◽  
The Pacific ◽  
Westerly Winds ◽  
Latitudinal Position ◽  
Basin Response

Abstract. The Southern Hemisphere westerly winds (SHWWs) play a major role in controlling wind-driven upwelling of Circumpolar Deep Water (CDW) and outgassing of CO2 in the Southern Ocean, on interannual to glacial–interglacial timescales. Despite their significance in the global carbon cycle, our understanding of millennial- and 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 δ13C 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 δ18O and δ13C, 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.

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

2017 ◽  
Author(s):  
Imogen M. Browne ◽  
Christopher M. Moy ◽  
Christina R. Riesselman ◽  
Helen L. Neil ◽  
Lorelei G. Curtin ◽  
...  
Keyword(s):  
New Zealand ◽  
Late Holocene ◽  
Drainage Basin ◽  
Southern Oscillation ◽  
Southern Annular Mode ◽  
Ice Age ◽  
The Pacific ◽  
Westerly Winds ◽  
Latitudinal Position ◽  
Paleoclimate Records

Abstract. The Southern Hemisphere westerly winds (SHWW) play a major role in controlling wind-driven upwelling of Circumpolar Deep Water (CDW) and outgassing of CO2 in the Southern Ocean on interannual to glacial-interglacial timescales. Despite their significance in the global carbon cycle, our understanding of millennial-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 paleoclimate records from comparable latitudes. Here, we reconstruct middle to late Holocene variability in the SHWW 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. Drainage basin response to variability in the strength of the SHWW at this latitude is reconstructed from downcore variations in magnetic susceptibility (MS) and bulk organic δ13C and atomic C/N, which monitor influxes of lithogenous and terrestrial vs marine organic matter, respectively. The hydrographic response to SHWW variability is reconstructed using benthic foraminifer δ18O and δ13C, 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 ~ 1600–900 yr BP at subantarctic latitudes that is broadly consistent with previous studies of vegetation response to climate at the Auckland Islands. Comparison with a SHWW reconstruction using similar proxies from Fiordland suggests a northward migration of the SHWW over New Zealand at the beginning of the Little Ice Age (LIA). Comparison with paleoclimate and paleoceanographic records from southern South America and the western Antarctic Peninsula indicates a late Holocene strengthening of the SHWW after ~ 1600 yr BP that appears to be broadly symmetrical across the Pacific basin, although our reconstruction suggests that this symmetry breaks down during the LIA. Contemporaneous increases in SHWW at localities 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 (SAM) and El Niño Southern Oscillation (ENSO).

scholarly journals Decadal Variability of the ENSO Teleconnection to the High-Latitude South Pacific Governed by Coupling with the Southern Annular Mode*

2006 ◽  
Vol 19 (6) ◽  
pp. 979-997 ◽  
Author(s):  
Ryan L. Fogt ◽  
David H. Bromwich
Keyword(s):  
High Latitude ◽  
Decadal Variability ◽  
Southern Oscillation ◽  
Phase Relationship ◽  
South Pacific ◽  
Southern Annular Mode ◽  
Height Anomaly ◽  
Austral Spring ◽  
Annular Mode ◽  
The Pacific

Abstract Decadal variability of the El Niño–Southern Oscillation (ENSO) teleconnection to the high-latitude South Pacific is examined by correlating the European Centre for Medium-Range Weather Forecasts (ECMWF) 40-yr Re-Analysis (ERA-40) and observations with the Southern Oscillation index (SOI) over the last two decades. There is a distinct annual contrast between the 1980s and the 1990s, with the strong teleconnection in the 1990s being explained by an enhanced response during austral spring. Geopotential height anomaly composites constructed during the peak ENSO seasons also demonstrate the decadal variability. Empirical orthogonal function (EOF) analysis reveals that the 1980s September–November (SON) teleconnection is weak due to the interference between the Pacific–South American (PSA) pattern associated with ENSO and the Southern Annular Mode (SAM). An in-phase relationship between these two modes during SON in the 1990s amplifies the height and pressure anomalies in the South Pacific, producing the strong teleconnections seen in the correlation and composite analyses. The in-phase relationship between the tropical and high-latitude forcing also exists in December–February (DJF) during the 1980s and 1990s. These results suggest that natural climate variability plays an important role in the variability of SAM, in agreement with a growing body of literature. Additionally, the significantly positive correlation between ENSO and SAM only during times of strong teleconnection suggests that both the Tropics and the high latitudes need to work together in order for ENSO to strongly influence Antarctic climate.

scholarly journals Atmospheric Meridional Moisture Flux over the Southern Ocean: A Story of the Amundsen Sea

2013 ◽  
Vol 26 (20) ◽  
pp. 8055-8064 ◽  
Author(s):  
Maria Tsukernik ◽  
Amanda H. Lynch
Keyword(s):  
Southern Ocean ◽  
Moisture Transport ◽  
Southern Oscillation ◽  
Moisture Flux ◽  
Southern Annular Mode ◽  
Complex Nature ◽  
Regional Variability ◽  
Amundsen Sea ◽  
The Pacific ◽  
Meridional Moisture Transport

Abstract The Antarctic ice sheet constitutes the largest reservoir of freshwater on earth, representing tens of meters of sea level rise if it were to melt completely. However, because of the remote location of the continent and the concomitant sparse data coverage, much remains unknown regarding the climate variability in Antarctica and the surrounding Southern Ocean. This study uses the high-resolution ECMWF Interim Re-Analysis (ERA-Interim) data during 1979–2010 to calculate the meridional moisture transport associated with the mean circulation, planetary waves, and synoptic-scale systems. The resulting moisture flux, which is dominated by the synoptic scales, is largely consistent with results from theoretical assumptions and previous studies. Here, high interannual and regional variability in the total meridional moisture flux is found, with no significant trend over the last 30 years. Further, the variability of the meridional moisture flux cannot be explained by the southern annular mode or El Niño–Southern Oscillation, even in the Pacific sector. In addition, the Amundsen Sea sector experiences the highest variability in meridional moisture transport and reveals a statistically significant decrease in the moisture flux at synoptic scales along the coastal zone. These results suggest that the Amundsen Sea provides a window on the complex nature of atmospheric moisture transport in the high southern latitudes.

Coincident recruitment patterns of Southern Hemisphere fishes

2016 ◽  
Vol 73 (2) ◽  
pp. 270-278 ◽  
Author(s):  
Claudio Castillo-Jordán ◽  
Neil L. Klaer ◽  
Geoffrey N. Tuck ◽  
Stewart D. Frusher ◽  
Luis A. Cubillos ◽  
...  
Keyword(s):  
South Africa ◽  
New Zealand ◽  
Southern Hemisphere ◽  
Southern Oscillation ◽  
Global Climate ◽  
Southern Annular Mode ◽  
Fish Stock ◽  
Climate Indices ◽  
Dynamic Factor ◽  
Recruitment Patterns

Three dominant recruitment patterns were identified across 30 stocks from Australia, New Zealand, Chile, South Africa, and the Falkland Islands using data from 1980 to 2010. Cluster and dynamic factor analysis provided similar groupings. Stocks exhibited a detectable degree of synchrony among species, in particular the hakes and lings from Australia, New Zealand, Chile, and South Africa. We tested three climate indices, the Interdecadal Pacific Oscillation (IPO), Southern Annular Mode (SAM), and Southern Oscillation Index (SOI), to explore their relationship with fish stock recruitment patterns. The time series of IPO and SOI showed the strongest correlation with New Zealand hoki (blue grenadier, Macruronus novaezelandiae) and Australian jackass morwong (Nemadactylus macropterus) (r = 0.50 and r = –0.50), and SAM was positively related to Australian Macquarie Island Patagonian toothfish (Dissostichus eleginoides) (r = 0.49). Potential linkages in recruitment patterns at sub-basin, basin, and multibasin scales and regional and global climate indices do account for some of the variation, playing an important role for several key Southern Hemisphere species.

scholarly journals Supplementary material to "Late Holocene intensification of the westerly winds at the subantarctic Auckland Islands (51° S), New Zealand"

2017 ◽  
Author(s):  
Imogen M. Browne ◽  
Christopher M. Moy ◽  
Christina R. Riesselman ◽  
Helen L. Neil ◽  
Lorelei G. Curtin ◽  
...  
Keyword(s):  
New Zealand ◽  
Late Holocene ◽  
Westerly Winds ◽  
Supplementary Material

Asynchronous Droughts in California Streamflow as Reconstructed from Tree Rings

1993 ◽  
Vol 39 (3) ◽  
pp. 290-299 ◽  
Author(s):  
Christopher J. Earle
Keyword(s):  
Southern Oscillation ◽  
Western United States ◽  
Historical Period ◽  
Winter Storms ◽  
Central California ◽  
The Pacific ◽  
Latitudinal Position ◽  
High Flows ◽  
Western Washington ◽  
The Mean

AbstractStreamflow since 1560 A.D. for four rivers within the Sacramento River Basin, California, has been reconstructed dendroclimatically. Both the highest and the lowest reconstructed streamflows occurred during the historical period, with high flows from 1854 to 1916 and low flows from 1917 to 1950. Prolonged (decade-scale) excursions from the mean have been the norm throughout the reconstructed period. The periods of high and low streamflow in the Sacramento Basin are generally synchronous with wet and dry periods reconstructed by dendroclimatic studies in the western United States. The record indicates a number of asynchronous droughts or wet years. The strongest contrasts are developed between northern (western Washington and Oregon or the Columbia Basin) and southern (the Sacramento Basin or central California) climate regions. These asynchronous events may be due to variation in the latitude of the subtropical high and in the latitudinal position of winter storms coming off the Pacific. No association was found with El Niño-Southern Oscillation events.

scholarly journals Cloud responses to climate variability over the extratropical oceans as observed by MISR and MODIS

2019 ◽  
Vol 19 (11) ◽  
pp. 7547-7565 ◽  
Author(s):  
Andrew Geiss ◽  
Roger Marchand
Keyword(s):  
Optical Depth ◽  
Southern Oscillation ◽  
Temporal Trends ◽  
Southern Annular Mode ◽  
Reanalysis Data ◽  
Cloud Optical Depth ◽  
Weather Forecasts ◽  
Maximum Covariance Analysis ◽  
The North ◽  
The Pacific

Abstract. Linear temporal trends in cloud fraction over the extratropical oceans, observed by NASA's Multi-angle Imaging SpectroRadiometer (MISR) during the period from 2000 to 2013, are examined in the context of coincident European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis data using a maximum covariance analysis. Changes in specific cloud types defined with respect to cloud-top height and cloud optical depth are related to trends in reanalysis variables. A pattern of reduced high-altitude optically thick cloud and increased low-altitude cloud of moderate optical depth is found to be associated with increased temperatures, geopotential heights, and anti-cyclonic flow over the extratropical oceans. These and other trends in cloud occurrence are shown to be correlated with changes in the El Niño–Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), the North Pacific index (NPI), and the Southern Annular Mode (SAM).

scholarly journals Siple Dome shallow ice cores: a study in coastal dome microclimatology

2014 ◽  
Vol 10 (3) ◽  
pp. 1253-1267 ◽  
Author(s):  
T. R. Jones ◽  
J. W. C. White ◽  
T. Popp
Keyword(s):  
Southern Oscillation ◽  
Ice Cores ◽  
Southern Annular Mode ◽  
Snow Accumulation ◽  
West Antarctica ◽  
Spatial Gradients ◽  
West Antarctic ◽  
The Pacific ◽  
Siple Dome ◽  
Borehole Temperatures

Abstract. Ice cores at Siple Dome, West Antarctica, receive the majority of their precipitation from Pacific Ocean moisture sources. Pacific climate patterns, particularly the El Niño–Southern Oscillation (ENSO) and the Southern Annular Mode (SAM), affect local temperature, atmospheric circulation, snow accumulation, and water isotope signals at Siple Dome. We examine borehole temperatures, accumulation, and water isotopes from a number of shallow ice cores recovered from a 60 km north–south transect of the dome. The data reveal spatial gradients partly explained by orographic uplift, as well as microclimate effects that are expressed differently on the Pacific and inland flanks. Our analyses suggest that while an ENSO and SAM signal are evident at Siple Dome, differences in microclimate and possible postdepositional movement of snow makes climate reconstruction problematic, a conclusion which should be considered at other West Antarctic coastal dome locations.

Coseismic Uplift of Holocene Marine Terraces in the Pakarae River Area, Eastern North Island, New Zealand

1991 ◽  
Vol 35 (3-Part1) ◽  
pp. 331-346 ◽  
Author(s):  
Yoko Ota ◽  
Alan G. Hull ◽  
Kelvin R. Berryman
Keyword(s):  
New Zealand ◽  
Late Holocene ◽  
Active Fault ◽  
Uplift Rate ◽  
Altitudinal Distribution ◽  
Marine Transgression ◽  
Marine Terraces ◽  
The Pacific ◽  
Coastal Uplift ◽  
Northeastern Coast

AbstractHolocene marine terraces along 15 km of the northeastern coast of North Island record episodic tectonic uplift. A maximum of seven terraces are arranged in staircase fashion and lie about 20 km above the subduction interface between the Pacific and Australian plates. The highest (T1) corresponds with the maximum of the Holocene marine transgression about 6700 14C yr B.P. Younger terraces are marine abrasion platforms overlain by thin beach deposits. Radiocarbon ages of marine shells from beach deposits indicate that uplift above marine conditions occurred ca. 6700(T1), 5500(T2), 3900(T3), 2500(4), 1600(T5), 1000(T6), and slightly younger than 600(T7) yr B.P. Uplift probably occurred coseismically. The maximum late Holocene uplift rate in the study area is 8 mm/yr. Altitudinal distribution of terraces suggests deformation exists as a ca. 20-km elongate dome, broken at the southern end by the Pakarae fault, which trends across the dome. Rupture on this fault has accompanied the growth of the dome but is not responsible for it. Bathymetric profiling suggests that an active fault, parallel to and about 5 km offshore, is probably responsible for the episodic coastal uplift.

Different Modes of Variability over the Tasman Sea: Implications for Regional Climate*

2014 ◽  
Vol 27 (22) ◽  
pp. 8466-8486 ◽  
Author(s):  
Stefan Liess ◽  
Arjun Kumar ◽  
Peter K. Snyder ◽  
Jaya Kawale ◽  
Karsten Steinhaeuser ◽  
...  
Keyword(s):  
New Zealand ◽  
Surface Temperature ◽  
Southern Oscillation ◽  
Southern Annular Mode ◽  
Empirical Orthogonal Functions ◽  
Seasonal Temperature ◽  
Orthogonal Functions ◽  
Tasman Sea ◽  
Eastern Australia ◽  
Precipitation Anomalies

Abstract A new approach is used to detect atmospheric teleconnections without being bound by orthogonality (such as empirical orthogonal functions). This method employs negative correlations in a global dataset to detect potential teleconnections. One teleconnection occurs between the Tasman Sea and the Southern Ocean. It is related to El Niño–Southern Oscillation (ENSO), the Indian Ocean dipole (IOD), and the southern annular mode (SAM). This teleconnection is significantly correlated with SAM during austral summer, fall, and winter, with IOD during spring, and with ENSO in summer. It can thus be described as a hybrid between these modes. Given previously found relationships between IOD and ENSO, and IOD’s proximity to the teleconnection centers, correlations to IOD are generally stronger than to ENSO. Increasing pressure over the Tasman Sea leads to higher (lower) surface temperature over eastern Australia (the southwestern Pacific) in all seasons and is related to reduced surface temperature over Wilkes Land and Adélie Land in Antarctica during fall and winter. Precipitation responses are generally negative over New Zealand. For one standard deviation of the teleconnection index, precipitation anomalies are positive over Australia in fall, negative over southern Australia in winter and spring, and negative over eastern Australia in summer. When doubling the threshold, the size of the anomalous high-pressure center increases and annual precipitation anomalies are negative over southeastern Australia and northern New Zealand. Eliassen–Palm fluxes quantify the seasonal dependence of SAM, ENSO, and IOD influences. Analysis of the dynamical interactions between these teleconnection patterns can improve prediction of seasonal temperature and precipitation patterns in Australia and New Zealand.

Sign in / Sign up

Export Citation Format

Share Document