Keith D. Williams

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The equilibrium climate sensitivity (ECS) of the two perturbed physics ensembles (PPE) generated using structurally different GCMs, MIROC3.2 and HadSM3, is investigated. We develop a method to quantify the SW cloud feedback by clouds with different cloud top pressure. We find that the difference in the ensemble means of the ECS between the two ensembles is(More)
[1] Global mean cloud feedbacks in ten atmosphere-only climate models are estimated in perturbed sea surface temperature (SST) experiments and the results compared to doubled CO 2 experiments using mixed-layer ocean versions of these same models. The cloud feedbacks in any given model are generally not consistent: the sign of the net cloud radiative(More)
A community diagnostics and performance met-rics tool for the evaluation of Earth system models (ESMs) has been developed that allows for routine comparison of single or multiple models, either against predecessor versions or against observations. The priority of the effort so far has been to target specific scientific themes focusing on selected essential(More)
An extended cloud-clustering method to assess the seasonal variation of clouds is applied to five CMIP5 models. The seasonal variation of the total cloud radiative effect (CRE) is dominated by variations in the relative frequency of occurrence of the different cloud regimes. Seasonal variations of the CRE within the individual regimes contribute much less.(More)
BACKGROUND CONTEXT The North American Spine Society's (NASS) Evidence-Based Clinical Guideline for the Diagnosis and Treatment of Adult Isthmic Spondylolisthesis features evidence-based recommendations for diagnosing and treating adult patients with isthmic spondylolisthesis. The guideline is intended to reflect contemporary treatment concepts for(More)
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