An Investigation of the Southern Ocean Surface Temperature Variability Using Long-Term Optimum Interpolation SST Data

Abstract

An attempt is made to understand the long-term variability of SST using NOAA optimum interpolation SST data for the period (1982–2011) in the Southern Ocean. This dataset has been used (i) to study the interannual variability in SST anomaly and (ii) to carry out regression analysis to compute linear trend in the annual averaged Southern Ocean SST. It is observed that summer season exhibits more variability than winter. Moreover, El Nino/La Nina events apparently play a critical role in the variability of Southern Ocean SST. Thus, higher SST anomalies were observed in El Nino years (e.g., 1983), while cooler anomalies were seen during La Nina years (e.g., 1985). In addition, the eastern and western sides of Antarctica experience episodes of warm and cold SST. Western parts of the Southern Ocean experienced higher anomalies during 1992, 1993, and 1994, while the eastern part experienced positive anomalies in 1997, 1998, 2002, and 2003. The paper also highlights the different regions of the Southern Ocean showing statistically significant positive/negative trends in the variability of interannual average SST. However, in general, the Southern Ocean as a whole is showing a weak interannual cooling trend in SST.

Antarctic icebergs: A significant natural ocean sound source in the Southern Hemisphere

“…In the Pacific, ice volume begins decreasing in 2009, after the disintegration of C19a and B15a. Regional and temporal differences in iceberg volume, and sound level reflect the local distribution and stability of the ice sheets, iceberg drift paths, and sea-surface temperature anomalies [e.g., Maheshwari et al, 2013]. Romanov et al [2014] found possible links between El Niño events and iceberg concentration in the east Pacific and in the west Atlantic sectors of Southern Ocean but the results were still inconclusive.…”

Diatom Phenology in the Southern Ocean: Mean Patterns, Trends and the Role of Climate Oscillations

“…Although we could not estimate trends in the bloom start date and bloom end date, we can expect a similar pattern to the ones detected for date of Dia-Chla maximum since these indices are highly correlated ( Figure S1 in the supplement). These observations combined with recent studies on the trends in sea surface temperature [64] and sea ice cover [65] over the last three decades, suggest a link between these two variables and the diatom phenology. For example, in the region south of 60 • S and from 60 • E to 120 • E (Figure 7, grey star) the earlier date of Dia-Chla maximum and the increased Dia-Chla maximum coincide with the observed increase trend in SST and decrease in sea ice cover (earlier sea ice melt).…”

Evidence for the Impact of Climate Change on Primary Producers in the Southern Ocean

“…It is increasingly clear that the response of phytoplankton to multiple stressors acting concurrently cannot be obtained by superimposing their separate responses (Boyd and Brown, 2015;Zhu et al, 2016;Boyd et al, 2016;Luxem et al, 2017;Andrew et al, 2019;Strzepek et al, 2019;Trimborn et al, 2019;Boyd, 2019). Satellite observations in the Southern Ocean show complex patterns of environmental change; surface warming in much of the Northern zone contrasts with slight cooling trends over the last 40 years further south (Maheshwari et al, 2013;Kostov et al, 2016;Sallée, 2018); average sea ice concentration has decreased in the Amundsen Sea but increased in parts of the Weddell, Bellingshausen and Ross Seas (Vaughan et al, 2013;Zhang et al, 2018;Pinkerton, 2019;IPCC, 2019); irradiance at the sea-surface has increased north of the Subantarctic Front and generally reduced to the south over the last 20 years; over the same period, mixed-layer depths have likely shallowed in the Northern zone, and both deepened and shallowed in different parts of the Subantarctic and Antarctic zones (Leung et al, 2015;Pinkerton, 2019).…”