Sensitivity

The value added by atmospheric measurements to the analyses and forecasts produced by data assimilation systems (DAS) is closely determined by the representation of the statistical properties of the errors in the prior forecast estimate (background) and observations. Four-dimensional variational data assimilation (4D-Var) aims to provide an optimal estimate to the initial state by solving a large-scale PDE model-constrained optimization problem.

Transmission topology optimization (line switching) supports congestion management by routing power flow away from congested / overloaded facilities to the rest of the system which has spare capacity. The result is an increase in transfer capabilities from low-cost resources to demand centers with significant potential for economic and reliability benefits. However, due to the computational complexity of the problem, its use has been limited, employed on an ad-hoc basis and relying on operators’ previous experience or a set of fixed procedures.

Soil structure is the arrangement of soil particles into secondary units called aggregates or peds. These manifest the cumulative effect of local pedogenic processes and influence soil behaviour - especially as it pertains to aeration and hydrophysical properties. One of the most direct methods of probing and characterizing soil structure is the analysis of the spatial arrangement of pore and solid spaces on images of sections of resin-impregnated soil or non-disruptive CT scanning.

The representation of subgrid scale processes introduces many poorly constrained parameters into mathematical representations of the climate system, contributing substantial uncertainty in model projections of climate change, especially for variables such as precipitation. This talk will outline a few pragmatic problems where connection to the stochastic community may be productive.