Advanced Scientific Computing Research

Recent Content

Recent Highlights

Algorithms and software were developed to solve a key challenge, property preservation, in modeling atmospheric transport of trace constituent species, such as water vapor, trace gases, and aerosols. These methods will speed up global climate models.
As mass loss from the Greenland and Antarctic ice sheets accelerates, climate modelers recognize the importance of dynamic ice sheet models for predicting future mass loss and sea level rise. The Community Ice Sheet Model (CISM) version 2.1 has been significantly improved and, as a result of these...
The biggest uncertainty in near-future sea level rise (SLR) comes from the Antarctic Ice Sheet. Antarctic ice flows in relatively fast-moving ice streams from the interior to the ocean, where it is carried into enormous floating ice shelves which push back on their feeder ice streams, buttressing...
The description of physical processes in weather and climate models involves many tunable parameters. A new strategy to optimize these parameters is presented based on surrogate models. It is applied to the one-dimensional parameterization of the boundary-layer and the benefits in terms of...
Hyperdiffusion is used in atmospheric models to eliminate spurious, unphysical noise that emerges from the way numerical methods represent the atmosphere.  This paper uses a theoretical analysis to compute the optimal amount of hyperdiffusion needed by atmospheric models using the spectral element...
We derived equations that represent organismal maturation as a function of variable environmental conditions, such as variation in temperature that capture the effects of random variation but which do not require computationally expensive Monte Carlo simulations (replications of variable...
A highly-resolved model of the West Antarctic Ice Sheet is used to examine the processes regulating basin-wide ice mass loss. This study finds that rates of mass loss are especially sensitive near the point the system transitions into a regime of self-sustained retreat where the effects of...
The DOE Energy Exascale Earth System Model (E3SM) project is developing a new non-hydrostatic dynamical core for modeling atmospheric fluid dynamics at high resolution. This work canvassed over 250 integration methods and solvers to determine the most promising approaches for the new dynamical core...
Moulins are the conduits that allow water melting on the surface of the Greenland Ice Sheet to drain to its base and cause the ice to flow faster.  This study compared moulins mapped from satellite-images to computer simulations of stresses in the ice constrained by hourly, on-site ice velocity...
We present a new discrete representation of non-hydrostatic vertical motions in the atmosphere based on a generalization of grid staggering to finite elements. The result is a model that is efficiently implemented in parallel, is arbitrarily accurate in space, and shows superior wave dispersion...

Recent Publications

Atmospheric tracer transport is a computationally demanding component of the atmospheric dynamical core of weather and climate simulations. Simulations typically have tens to hundreds of tracers. A tracer field is required to preserve several properties, including mass, shape, and tracer...
We describe and evaluate version 2.1 of the Community Ice Sheet Model (CISM). CISM is a parallel, 3-D thermomechanical model, written mainly in Fortran, that solves equations for the momentum balance and the thickness and temperature evolution of ice sheets. CISM's velocity solver incorporates a...
The Antarctic Ice Sheet (AIS) remains the largest uncertainty in projections of future sea level rise. A likely climate‐driven vulnerability of the AIS is thinning of floating ice shelves resulting from surface‐melt‐driven hydrofracture or incursion of relatively warm water into subshelf ocean...
Physical parameterizations in global atmospheric and ocean models typically include free parameters that are not theoretically or empirically constrained. New methods are required to determine the optimal parameter combinations for such models in an objective, exhaustive, yet computationally...
The spectral element method (SEM) is a mimetic finite element method with several properties that make it a desirable choice for numerical modeling. Although the linear dispersion properties of this method have been analyzed extensively for the case of the 1D inviscid advection equation, practical...
Phenology models are becoming increasingly important tools to accurately predict how climate change will impact the life histories of organisms. We propose a class of integral projection phenology models derived from stochastic individual‐based models of insect development and demography. Our...
Rapid change now underway on Thwaites Glacier (TG) raises concern that a threshold for unstoppable grounding line retreat has been or is about to be crossed. We use a high-resolution ice sheet model to examine the mechanics of TG self-sustained retreat by nudging the grounding line just past the...
The efficient simulation of non-hydrostatic atmospheric dynamics requires time integration methods capable of overcoming the explicit stability constraints on time step size arising from acoustic waves. In this work, we investigate various implicit-explicit (IMEX) additive Runge-Kutta (ARK) methods...
Moulins permit access of surface meltwater to the glacier bed, causing basal lubrication and ice speedup in the ablation zone of western Greenland during summer. Despite the substantial impact of moulins on ice dynamics, the conditions under which they form are poorly understood. We assimilate a...
Atmospheric modeling systems require economical methods to solve the non-hydrostatic Euler equations. Two major differences between hydrostatic models and a full non-hydrostatic description lie in the vertical velocity tendency and numerical stiffness associated with sound waves. In this work, we...