CESM1.2 atmospheric surface fields for pre-industrial Southern Ocean hosing experiments

• Main Authors: Bakker, Pepijn, Prange, Matthias
• Format: Dataset
• Language: English
• Published: PANGAEA 2018
• Subjects: Center for Marine Environmental Sciences; File content; File format; File name; File size; MARUM; Uniform resource locator/link to file; Antarctic; Southern Ocean; The Antarctic; Pollard; Bakker; Antarc*; Ice Sheet; Sea ice
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.891414; https://doi.org/10.1594/PANGAEA.891414

Introduction We use high-resolution coupled ocean-atmosphere simulations to show that reasonable past melt rates of the Antarctic Ice Sheet can have led to shifts of the ITCZ through large-scale surface air temperature changes over the Southern Ocean. Through sensitivity experiments employing slightly negative to large positive meltwater fluxes we deduce that meridional shifts of the Hadley cell and therewith the ITCZ are, to a first order, a linear response to Southern Hemisphere high-latitude surface air temperature changes and Antarctic Ice Sheet melt rates. Methods The simulations were performed using the Community Earth System Model version1.2 (CESM1.2), a global climate model that includes interactive atmosphere (CAM4), ocean (POP2), land (CLM4.0; including carbon-nitrogen dynamics), and sea-ice (CICE4) components. For the atmosphere (running with a finite volume dynamical core) and land a horizontal resolution of 0.9° x 1.25° was used with the former having 26 vertical levels. The ocean and sea-ice components use a displaced dipole grid with a nominal horizontal resolution of 1° . The ocean grid has 60 levels. The AIS contribution to meltwater pulse 1A [Clark et al., 1996, doi:10.1029/96PA01419] is highly uncertain, but in the most thorough attempt thus far to quantify this flux, a mean value of 0.034 Sv was found, with maximum values up to 0.11 Sv for a period of 350 years [Golledge et al., 2014, doi:10.1038/ncomms6107]. The Holocene AIS variability suggested by Bakker et al. [2017, doi:10.1038/nature20582] is 0.048 Sv (1σ). Finally, the future response of the AIS if global warming is to continue in the next centuries again varies widely, ranging from ∼0.2-0.5 Sv for the year 2100 in, respectively the so-called Representative Concentration Pathway (RCP) scenario 4.5 and RCP8.5 [Meinshausen et al., 2011, doi:10.1007/s10584-011-0156-z], and ranging from ∼0.2-0.25 Sv for the year 2500 in again RCP4.5 and RCP8.5, respectively [deConto and Pollard , 2016, doi:10.1038/nature17145]. Taken together, credible ...