Abstracts

CaGIS vol. 32, no. 1

Climate Forecast Maps as a Communication and Decision-Support Tool: An Empirical Test with Prospective Policy Makers

Toru Ishikawa, Anthony G. Barnston, Kim A. Kastens, Patrick Louchouarn, and Chester F. Ropelewski

This paper reports an empirical study of communication issues concerning climate forecasts. Students in a professional master’s degree (MPA) program in environmental science and policy participated in the study as prospective policy makers. Participants viewed a set of currently issued precipitation forecast maps, and answered questions designed to assess, in the context relevant to agricultural and environmental decision-making, their understanding and evaluation of the maps. Participants failed to understand some aspects of the information shown on the maps, in the current design, as the map makers intended. In particular, participants had difficulty understanding probability forecast maps and distinguishing probabilistic three category forecasts and the amount of precipitation. Most participants evaluated the degree of agreement between the forecast and observation as “agree only slightly” or “agree somewhat.” More than half of the participants were not inclined to use the forecasts in agricultural decision-making. Implications for improvement in design for better communication are discussed.

KEYWORDS: Cartographic communication, climate forecasts, probabilities, uncertainty, decision making, policy makers

Cubic Map Algebra Functions for Spatio-Temporal Analysis

Jeremy Mennis, Roland Viger, and C. Dana Tomlin

We propose an extension of map algebra to three dimensions for spatio-temporal data handling. This approach yields a new class of map algebra functions that we call "cube functions." Whereas conventional map algebra functions operate on data layers representing two-dimensional space, cube functions operate on data cubes representing two-dimensional space over a third-dimensional period of time. We describe the prototype implementation of a spatio-temporal data structure and selected cube function versions of conventional local, focal, and zonal map algebra functions. The utility of cube functions is demonstrated through a case study analyzing the spatio-temporal variability of remotely sensed, southeastern U.S. vegetation character over various land covers and during different El Niño/Southern Oscillation (ENSO) phases. Like conventional map algebra, the application of cube functions may demand significant data preprocessing when integrating diverse data sets, and are subject to limitations related to data storage and algorithm performance. Solutions to these issues include extending data compression and computing strategies for calculations on very large data volumes to spatio-temporal data handling.

Individual Differences in Map Reading Spatial Abilities Using Perceptual and Memory Processes

Robert Earl Lloyd and Rick L. Bunch

Central to spatial intelligence are the capacities to perceive the visual world accurately, to perform transformations and modifications upon one’s initial perceptions, and to be able to re-create aspects of one’s visual experiences, even in the absence of relevant physical stimulation. One can be asked to produce forms or simply to manipulate those that have been provided [Gardner 1983, p. 173].

The above quote is from a book on multiple intelligences that argues spatial intelligence is one of seven human intelligences. By this definition, the two main expressions of spatial intelligence are related to being accurate and using memory. Individuals can demonstrate their spatial intelligence in many ways. Some individuals might excel at navigating in unfamiliar environments while others are better at remembering the locations of landmarks in familiar environments (Galea and Kimura 1993; Silverman et al. 2000). The sex of an individual may reflect some environmental variables that are expressed through genetic factors. Both natural and sexual selection have been suggested as evolutionary processes that separate females and males on the basis of spatial abilities (Ecuyer-Dab and Robert 2004). The purpose of the current study is to consider the variation of a spatial ability related to map reading that might be explained by both biological and environmental variables. The basic problem was to conduct a map reading experiment that would require subjects to use both perceptual and memory processes. The research objective of the study was to model the variation of the efficiency of human performance on map-reading tasks with variables related to the nature of the task and the map readers.

Deriving New Minimum Cost Pathways from Existing Paths

Denis J. Dean

Without a priori cell traversing cost data, conventional GIS-based techniques cannot be used to find minimum cost paths from specified starting points to specified ending points. However, in one class of problems where these costs do not exist a priori, it may be possible to derive them. This class of problems is characterized by the presence of an existing minimum cost path that is subject to the same traversing cost mechanics as the new path that is being contemplated. This study developed and evaluated linear programming-based techniques for deriving both isotropic and anisotropic traversing costs from existing minimum cost pathways. The derived costs can then be used to find minimum cost routes for new pathways that are subject to the same cost mechanics as the existing pathways. The techniques presented here were evaluated by applying them to situations found in the forest road network of the Arapaho and Roosevelt National Forests (ARNF) in Colorado. In 18 of the 19 situations evaluated, the predicted routes generated using the techniques presented here agreed with actual roads found in the ARNF.

KEYWORDS: Cost spreading, linear programming, minimum cost paths, isotropic costs, anisotropic costs