Feasibility of acoustic thermometry of Arctic Ocean climate change

1993 ◽  
Vol 94 (3) ◽  
pp. 1760-1760
Author(s):  
Peter N. Mikhalevsky
Keyword(s):  
Climate Change ◽  
Arctic Ocean ◽  
Ocean Climate ◽  
Acoustic Thermometry

Acoustic thermometry for Arctic Ocean climate

2002 ◽  
Author(s):  
P.N. Mikhalevsky ◽  
R. Muench ◽  
A.B. Baggeroer
Keyword(s):  
Arctic Ocean ◽  
Ocean Climate ◽  
Acoustic Thermometry

scholarly journals Variability and decadal trends in the Isfjorden (Svalbard) ocean climate and circulation - an indicator for climate change in the European Arctic

2020 ◽  
Author(s):  
Ragnheid Skogseth ◽  
Lea L. A. Olivier ◽  
Frank Nilsen ◽  
Marius O. Jonassen ◽  
Eva Falck
Keyword(s):  
Climate Change ◽  
Arctic Ocean ◽  
Air Temperature ◽  
The Arctic ◽  
Weighted Mean ◽  
Ocean Climate ◽  
Weighted Mean Temperature ◽  
The Arctic Ocean ◽  
Local Mean ◽  
Type Water

<p>Isfjorden, a broad Arctic fjord in western Spitsbergen, has shown significant changes in hydrography and inflow of Atlantic Water (AW) the last decades that only recently have been observed in the Arctic Ocean north of Svalbard. Variability and trends in this fjord’s climate and circulation are therefore analysed from observational and reanalysis data during 1987 to 2017. Isfjorden experienced a shift in summer ocean structure in 2006, from AW generally in the bottom layer to AW (with increasing thickness) higher up in the water column. This shift, and a concomitant shift to less fast ice in Isfjorden are linked to positive trends in the mean sea surface temperature (SST) and volume weighted mean temperature (VT) in winter (SST<sub>w</sub>/VT<sub>w</sub>: 0.7 ± 0.1/0.9 ± 0.3 °C 10yr<sup>-1</sup>) and summer (SST<sub>S</sub>/VT<sub>S</sub>: 0.7 ± 0.1/0.6 ± 0.1 °C 10yr<sup>-1</sup>). The local mean air temperature shows similar trends in winter (1.9 ± 0.4 °C 10yr<sup>-1</sup>) and summer (0.7 ± 0.1 °C 10yr<sup>-1</sup>). Positive trends in volume weighted mean salinity in winter (0.21 ± 0.06 10yr<sup>-1</sup>) and summer (0.07 ± 0.05 10yr<sup>-1</sup>) suggest increased AW advection as a main reason for Isfjorden’s climate change. Local mean air temperature correlates significantly with sea ice cover, SST, and VT, revealing the fjord’s impact on the local terrestrial climate. In line with the shift in summer ocean structure, Isfjorden has changed from an Arctic type fjord dominated by Winter Deep and Winter Intermediate thermal and haline convection, to a fjord dominated by deep thermal convection of Atlantic type water (Winter Open). AW indexes for the mouth and Isfjorden proper show that AW influence has been common in winter over the last decade. Alternating occurrence of Arctic and Atlantic type water at the mouth mirrors the geostrophic control imposed by the Spitsbergen Polar Current (carrying Arctic Water) relative to the strength of the Spitsbergen Trough Current (carrying AW). During high AW impact events, Atlantic type water propagates into the fjord according to the cyclonic circulation along isobaths determined by the winter convection. This study demonstrates that Isfjorden and its ocean climate can be used as an indicator for climate change in the Arctic Ocean. The used methods may constitute a set of helpful tools for future studies also outside the Svalbard Archipelago.</p>

scholarly journals Regional variability of acidification in the Arctic: a sea of contrasts

2014 ◽  
Vol 11 (2) ◽  
pp. 293-308 ◽  
Author(s):  
E. E. Popova ◽  
A. Yool ◽  
Y. Aksenov ◽  
A. C. Coward ◽  
T. R. Anderson
Keyword(s):  
Climate Change ◽  
Primary Production ◽  
Arctic Ocean ◽  
Canadian Arctic ◽  
Atmospheric Co2 ◽  
The Arctic ◽  
Canadian Arctic Archipelago ◽  
Regional Variability ◽  
The Arctic Ocean ◽  
The Impact

Abstract. The Arctic Ocean is a region that is particularly vulnerable to the impact of ocean acidification driven by rising atmospheric CO2, with potentially negative consequences for calcifying organisms such as coccolithophorids and foraminiferans. In this study, we use an ocean-only general circulation model, with embedded biogeochemistry and a comprehensive description of the ocean carbon cycle, to study the response of pH and saturation states of calcite and aragonite to rising atmospheric pCO2 and changing climate in the Arctic Ocean. Particular attention is paid to the strong regional variability within the Arctic, and, for comparison, simulation results are contrasted with those for the global ocean. Simulations were run to year 2099 using the RCP8.5 (an Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) scenario with the highest concentrations of atmospheric CO2). The separate impacts of the direct increase in atmospheric CO2 and indirect effects via impact of climate change (changing temperature, stratification, primary production and freshwater fluxes) were examined by undertaking two simulations, one with the full system and the other in which atmospheric CO2 was prevented from increasing beyond its preindustrial level (year 1860). Results indicate that the impact of climate change, and spatial heterogeneity thereof, plays a strong role in the declines in pH and carbonate saturation (Ω) seen in the Arctic. The central Arctic, Canadian Arctic Archipelago and Baffin Bay show greatest rates of acidification and Ω decline as a result of melting sea ice. In contrast, areas affected by Atlantic inflow including the Greenland Sea and outer shelves of the Barents, Kara and Laptev seas, had minimal decreases in pH and Ω because diminishing ice cover led to greater vertical mixing and primary production. As a consequence, the projected onset of undersaturation in respect to aragonite is highly variable regionally within the Arctic, occurring during the decade of 2000–2010 in the Siberian shelves and Canadian Arctic Archipelago, but as late as the 2080s in the Barents and Norwegian seas. We conclude that, for future projections of acidification and carbonate saturation state in the Arctic, regional variability is significant and needs to be adequately resolved, with particular emphasis on reliable projections of the rates of retreat of the sea ice, which are a major source of uncertainty.

ATOC and Other Acoustic Thermometry Observations In New Zealand

1999 ◽  
Vol 33 (1) ◽  
pp. 55-60
Author(s):  
C.T. Tindle ◽  
G.E.J.
Keyword(s):  
New Zealand ◽  
Ocean Bottom ◽  
Underwater Sound ◽  
Floating Platform ◽  
Ocean Climate ◽  
Acoustic Thermometry ◽  
Tasman Sea ◽  
Heard Island ◽  
Large Fluctuations ◽  
Feasibility Test

A summary of participation of the New Zealand group in the ATOC (Acoustic Thermometry of Ocean Climate) program over a five year period is presented. Transmissions from Heard Island were observed in the Tasman Sea during the Heard Island Feasibility Test in 1991. The California-New Zealand underwater sound path was verified with explosive sources in 1992. Single hydrophone observations were made of transmissions to New Zealand from California from an electrically driven source first suspended beneath a floating platform in 1994 and later placed on the ocean bottom at Pioneer Seamount in 1995. Results from these experiments show that acoustic propagation to ranges of order 10 Mm appears to be characterised by large fluctuations occurring with a time scale of a few minutes.

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