Jim, You should read through the whole tread but here is one post from ASLR. Much of the thread has to do with Antacrtic bottom water formation and further info on the North Atlantic Bottom water processes are necessary for a full picture of bottom water. The Pacific doesn't have a northern hemispheric production site but the main site of bottom water return to surface waters occurred in the Eastern Equatorial Pacific. Residence times from creation to return are about a thousand years.
Re: Discussion of WAIS Collapse Main Period from 2060 to 2100
« Reply #47 on: July 12, 2013, 05:26:22 PM »
I am concerned that some readers are not familiar with the excellent work of Purkey and Johnson focused on AABW but also very important to the trends in warm CDW (see reply #9 in this trend, and in the first attached figure see the Weddell-Enderby temperature curve indicating warm water that could be contributing now to basal ice melting for FRIS). The following reference and abstract cites their continuing valuable work in 2013:
Antarctic Bottom Water warming and freshening: Contributions to sea level rise, ocean freshwater budgets, and global heat gain
by: Sarah G. Purkey, and Gregory C. Johnson; Journal of Climate 2013 ; doi: http://dx.doi.org/10.1175/JCLI-D-12-00834.1
Abstract: "Freshening and warming of Antarctic Bottom Water (AABW) between the 1980s and 2000s are quantified, assessing the relative contributions of water-mass changes and isotherm heave. The analysis uses highly accurate, full-depth, ship-based, conductivity-temperature-depth measurements taken along repeated oceanographic sections around the Southern Ocean. Fresher varieties of AABW are present within the South Pacific and South Indian oceans in 2000s compared to the 1990s, with the strongest freshening in the newest waters adjacent to the Antarctic continental slope and rise indicating a recent shift in the salinity of AABW produced in this region. Bottom waters in the Weddell Sea exhibit significantly less water-mass freshening than those in the other two southern basins. However, a decrease in the volume of the coldest, deepest waters is observed throughout the entire Southern Ocean. This isotherm heave causes a salinification and warming on isobaths from the bottom up to the shallow potential temperature maximum. The water-mass freshening of AABW in the Indian and Pacific sectors is equivalent to a freshwater flux of 73 ±26 Gt yr-1, roughly half of the estimated recent mass loss of the West Antarctic Ice Sheet. Isotherm heave integrated below 2000 m and south of 30 °S equates to a net heat uptake of 34 ±3 TW of excess energy entering the deep ocean from deep volume loss of AABW and 0.37 ±0.15 mm yr-1 of sea level rise from associated thermal expansion."
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