Michael D. Karcher

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The ability to simulate the past variability of the sea ice-ocean system is of fundamental interest for the identification of key processes and the evaluation of scenarios of future developments. To achieve this goal atmospheric surface fields are reconstructed by statistical means for the period 1900 to 1997 and applied to a coupled sea ice-ocean model of(More)
Monthly energetics of the Arctic Ocean are estimated based on results from six different coupled ice-ocean models. The components of the kinetic, potential and available potential energies, energy conversion and forcing rates are studied. The energy balances derived from the models differ significantly in the abyss, notably regarding the conversion of(More)
Phylodynamics seeks to estimate effective population size fluctuations from molecular sequences of individuals sampled from a population of interest. One way to accomplish this task formulates an observed sequence data likelihood exploiting a coalescent model for the sampled individuals' genealogy and then integrating over all possible genealogies via Monte(More)
Pacific Water (PW) enters the Arctic Ocean through Bering Strait and brings in heat, fresh water, and nutrients from the northern Bering Sea. The circulation of PW in the central Arctic Ocean is only partially understood due to the lack of observations. In this paper, pathways of PW are investigated using simulations with six state-of-the art regional and(More)
SUMMARY. I review the literature on the impact on student achievement of high-stakes testing. Its popularity as a mechanism for holding educators accountable has triggered studies to examine whether its promise to increase student learning has been fulfilled. The review concludes there is no consistent evidence to suggest high-stakes testing leads to(More)
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