scholarly journals Modelling the Antarctic marine cryosphere at the Last Glacial Maximum

2015 ◽  
Vol 56 (69) ◽  
pp. 425-435 ◽  
Author(s):  
Kazuya Kusahara ◽  
Tatsuru Sato ◽  
Akira Oka ◽  
Takashi Obase ◽  
Ralf Greve ◽  
...  
Keyword(s):  
Sea Ice ◽  
Last Glacial Maximum ◽  
Ocean Model ◽  
Glacial Maximum ◽  
Ice Shelf ◽  
Atlantic Sector ◽  
Ice Shelves ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

AbstractWe estimate the sea-ice extent and basal melt of Antarctic ice shelves at the Last Glacial Maximum (LGM) using a coupled ice-shelf-sea-ice-ocean model. The shape of Antarctic ice shelves, ocean conditions and atmospheric surface conditions at the LGM are different from those in the present day; these are derived from an ice-shelf-ice-sheet model, a sea-ice-ocean model and a climate model for glacial simulations, respectively. The winter sea ice in the LGM is shown to extend up to ∼7° of latitude further equatorward than in the present day. For the LGM summer, the model shows extensive sea-ice cover in the Atlantic sector and little sea ice in the other sectors. These modelled sea-ice features are consistent with those reconstructed from sea-floor sedimentary records. Total basal melt of Antarctic ice shelves in the LGM was ∼2147 Gt a–1, which is much larger than the present-day value. More warm waters originating from Circumpolar Deep Water could be easily transported into ice-shelf cavities during the LGM because the full glacial grounding line extended to shelf break regions and ice shelves overhung continental slopes. This increased transport of warm water masses underneath an ice shelf and into their basal cavities led to the high basal melt of ice shelves in the LGM.

Reconstruction of sea-surface temperature, salinity, and sea-ice cover in the northern North Atlantic during the last glacial maximum based on dinocyst assemblages

2000 ◽  
Vol 37 (5) ◽  
pp. 725-750 ◽  
Author(s):  
Anne de Vernal ◽  
Claude Hillaire-Marcel ◽  
Jean-Louis Turon ◽  
Jens Matthiessen
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Last Glacial Maximum ◽  
North Atlantic ◽  
Ice Cover ◽  
Glacial Maximum ◽  
Sea Surface ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Past sea-surface conditions over the northern North Atlantic during the last glacial maximum were examined from the study of 61 deep-sea cores. The last glacial maximum time slice studied here corresponds to an interval between Heinrich layers H2 and H1, and spanning about 20-16 ka on a 14C time scale. Transfer functions based on dinocyst assemblages were used to reconstruct sea-surface temperature, salinity, and sea-ice cover. The results illustrate extensive sea-ice cover along the eastern Canadian margins and sea-ice spreading, only during winter, over most of the northern North Atlantic. On the whole, much colder winter prevailed, despite relatively mild conditions in August (10-15°C at most offshore sites), thus suggesting a larger seasonal contrast of temperatures than today. Lower salinity than at present is reconstructed, especially along the eastern Canadian and Scandinavian margins, likely because of meltwater supply from the surrounding ice sheets. These reconstructions contrast with those established by CLIMAP on the basis of planktonic foraminifera. These differences are discussed with reference to the stratigraphical frame of the last glacial maximum, which was not the coldest phase of the last glacial stage. The respective significance of dinocyst and foraminifer records is also examined in terms of the thermohaline characteristics of surface waters and the vertical structure of upper water masses, which was apparently much more stratified than at present in the northern North Atlantic, thus preventing deep-water formation.

scholarly journals A global climatology of the ocean surface during the Last Glacial Maximum mapped on a regular grid (GLOMAP)

2021 ◽  
Vol 17 (2) ◽  
pp. 805-824
Author(s):  
André Paul ◽  
Stefan Mulitza ◽  
Rüdiger Stein ◽  
Martin Werner
Keyword(s):  
Sea Ice ◽  
Last Glacial Maximum ◽  
Climate Sensitivity ◽  
Ocean Surface ◽  
Glacial Maximum ◽  
Sea Ice Extent ◽  
Equilibrium Climate Sensitivity ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract. We present a climatology of the near-sea-surface temperature (NSST) anomaly and the sea-ice extent during the Last Glacial Maximum (LGM, 23 000–19 000 years before present) mapped on a global regular 1∘×1∘ grid. It is an extension of the Glacial Atlantic Ocean Mapping (GLAMAP) reconstruction of the Atlantic NSST based on the faunal and floral assemblage data of the Multiproxy Approach for the Reconstruction of the Glacial Ocean Surface (MARGO) project and several recent estimates of the LGM sea-ice extent. Such a gridded climatology is highly useful for the visualization of the LGM climate, calculation of global and regional NSST averages, and estimation of the equilibrium climate sensitivity, as well as a boundary condition for atmospheric general circulation models. The gridding of the sparse NSST reconstruction was done in an optimal way using the Data-Interpolating Variational Analysis (DIVA) software, which takes into account the uncertainty in the reconstruction and includes the calculation of an error field. The resulting Glacial Ocean Map (GLOMAP) confirms the previous findings by the MARGO project regarding longitudinal and meridional NSST differences that were greater than today in all oceans. Taken at face value, the estimated global and tropical cooling would imply an equilibrium climate sensitivity at the lower end of the currently accepted range. However, because of anticipated changes in the seasonality and thermal structure of the upper ocean during the LGM as well as uneven spatial sampling, the estimated cooling and implied climate sensitivity are likely to be biased towards lower values.

Sea-ice distribution and atmospheric pressure patterns in southwestern Okhotsk Sea since the Last Glacial Maximum

2010 ◽  
Vol 72 (3) ◽  
pp. 99-107 ◽  
Author(s):  
Kota Katsuki ◽  
Boo-Keun Khim ◽  
Takuya Itaki ◽  
Yusuke Okazaki ◽  
Ken Ikehara ◽  
...  
Keyword(s):  
Sea Ice ◽  
Last Glacial Maximum ◽  
Atmospheric Pressure ◽  
Glacial Maximum ◽  
Okhotsk Sea ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial
Sign in / Sign up

Export Citation Format

Share Document