Space-time dynamic design of environmental monitoring networks

Methods for constructing optimal spatial sampling designs for environmental monitoring networks, widely applied in a large number of disciplines, gene rally produce static designs that are optimal under models with no explicit temporal structure. However, environmental processes tend to exhibit both spatial and temporal variability; hence, static networks may not capture th e essential spatiotemporal variability of the process. Static designs, ofte n necessary due to geopolitical and economic considerations, could be suppl emented with mobile monitoring devices. The design problem is to decide whe re mobile monitors should be located at time t + 1 based on observations th rough time t. We propose a simple, general, dynamical space-time model that allows estimation of prediction error covariance at time t + 1, given info rmation up to time t. We then seek the optimal spatial locations at time t + 1 that satisfy some design criterion. Several experiments show the import ance of spatial and temporal structure in the selection of optimal designs. Data from the Chicago area ozone monitoring network are used to demonstrat e potential dynamical designs under realistic space-time dependence assumpt ions.