SEA SURFACE pCO2IN THE INDIAN SECTOR OF THE SOUTHERN OCEAN DURING AUSTRAL SUMMER OF 2009

Abstract. Centennial- and millennial-scale variability of Southern Ocean temperature over the Holocene is poorly known, due to both short instrumental records and sparsely distributed high-resolution temperature reconstructions, with evidence for past temperature variations in the region coming mainly from ice core records. Here we present a high-resolution (∼60 year), diatom-based sea surface temperature (SST) reconstruction from the western Indian sector of the Southern Ocean that spans the interval 14.2 to 1.0 ka (calibrated kiloyears before present). During the late deglaciation, the new SST record shows cool temperatures at 14.2–12.9 ka and gradual warming between 12.9 and 11.6 ka in phase with atmospheric temperature evolution. This supports the evolution of the Southern Ocean SST during the deglaciation being linked with a complex combination of processes and drivers associated with reorganisations of atmospheric and oceanic circulation patterns. Specifically, we suggest that Southern Ocean surface warming coincided, within the dating uncertainties, with the reconstructed slowdown of the Atlantic Meridional Overturning Circulation (AMOC), rising atmospheric CO2 levels, changes in the southern westerly winds and enhanced upwelling. During the Holocene the record shows warm and stable temperatures from 11.6 to 8.7 ka followed by a slight cooling and greater variability from 8.7 to 1 ka, with a quasi-periodic variability of 200–260 years identified by spectral analysis. We suggest that the increased variability during the mid- to late Holocene reflects the establishment of centennial variability in SST connected with changes in the high-latitude atmospheric circulation and Southern Ocean convection.

Download Full-text

Variations of net primary productivity and phytoplankton community composition in the Indian sector of the Southern Ocean as estimated from ocean color remote sensing data

Biogeosciences ◽

10.5194/bg-9-3875-2012 ◽

2012 ◽

Vol 9 (10) ◽

pp. 3875-3890 ◽

Cited By ~ 13

Author(s):

S. Takao ◽

T. Hirawake ◽

S. W. Wright ◽

K. Suzuki

Keyword(s):

Southern Ocean ◽

Community Composition ◽

Primary Productivity ◽

Phytoplankton Community ◽

Net Primary Productivity ◽

Austral Summer ◽

Remote Sensing Data ◽

The Past ◽

Phytoplankton Community Composition ◽

Indian Sector

Abstract. Phytoplankton population dynamics play an important role in biogeochemical cycles in the Southern Ocean during austral summer. Recent environmental changes such as a rise in sea surface temperature (SST) are likely to impact on net primary productivity (NPP) and phytoplankton community composition. However, their spatiotemporal relationships are still unclear in the Southern Ocean. Here we assessed the relationships between NPP, dominant phytoplankton groups, and SST in the Indian sector of the Southern Ocean over the past decade (1997–2007) using satellite remote sensing data. As a result, we found a statistically significant reduction in NPP in the polar frontal zone over the past decade during austral summer. Moreover, the decrease in NPP positively correlated with the dominance of diatoms (Kendall's rank correlation τ = 0.60) estimated by a phytoplankton community composition model, but not correlated with SST. In the seasonal ice zone, NPP correlated with not only the dominance of diatoms positively (τ = 0.56), but also the dominance of haptophytes (τ = −0.54) and SST (τ = −0.54) negatively. Our results suggested that summer NPP values were strongly affected by the phytoplankton community composition in the Indian sector of the Southern Ocean.

Download Full-text

Morphological variability of Emiliania huxleyi in the Indian sector of the Southern Ocean during the austral summer of 2010

Marine Micropaleontology ◽

10.1016/j.marmicro.2014.01.005 ◽

2014 ◽

Vol 107 ◽

pp. 44-58 ◽

Cited By ~ 11

Author(s):

Shramik M. Patil ◽

Rahul Mohan ◽

Suhas Shetye ◽

Sahina Gazi ◽

Syed Jafar

Keyword(s):

Southern Ocean ◽

Morphological Variability ◽

Austral Summer ◽

Emiliania Huxleyi ◽

Indian Sector

Download Full-text

Sea surface temperature in the Indian sector of the Southern Ocean over the Late Glacial and Holocene

10.5194/cp-2020-23 ◽

2020 ◽

Author(s):

Lisa C. Orme ◽

Xavier Crosta ◽

Arto Miettinen ◽

Dmitry V. Divine ◽

Katrine Husum ◽

...

Keyword(s):

High Resolution ◽

Southern Ocean ◽

Surface Temperature ◽

Sea Surface Temperature ◽

Late Glacial ◽

Meridional Overturning Circulation ◽

Sea Surface ◽

Oceanic Circulation ◽

Instrumental Records ◽

Indian Sector

Abstract. Centennial and millennial scale variability of Southern Ocean temperature is poorly known, due to both short instrumental records and sparsely distributed high-resolution temperature reconstructions, with evidence for past temperature variability instead coming mainly from ice core records. Here we present a high-resolution (~ 60 year), diatom-based sea-surface temperature (SST) reconstruction from the western Indian sector of the Southern Ocean that spans the interval 14.2 to 1.0 ka BP (calibrated kiloyears before present). During the late deglaciation, the new SST record shows cool temperatures at 14.2–12.9 ka BP and gradual warming between 12.9–11.6 ka BP in phase with atmospheric temperature evolution. This supports that the temperature of the Southern Ocean during the deglaciation was linked with a complex combination of processes and drivers associated with reorganisations of atmospheric and oceanic circulation patterns. Specifically, we suggest that Southern Ocean surface warming coincided, within the dating uncertainties, with the reconstructed slowdown of the Atlantic Meridional Overturning Circulation (AMOC), rising atmospheric CO2 levels, changes in the southern westerly winds and enhanced upwelling. During the Holocene the record shows warm and stable temperatures from 11.6–8.7 ka BP followed by a slight cooling and greater variability from 8.7 to 1 ka BP, with a quasi-periodic variability of 200–260 years as identified by spectral analysis. We suggest that the increased variability during the mid to late Holocene may reflect the establishment of centennial variability in SST connected with changes in the high latitude atmospheric circulation and Southern Ocean convection, as identified in models.

Download Full-text