Using linked micromap plots to characterize Omernik ecoregions

The paper introduces linked micromap (LM) plots for presenting environmenta l summaries. The LM template includes parallel sequences of micromap, label , and statistical summary graphics panels with attention paid to perceptual grouping, sorting and linking of the summary components. The applications show LM plots for Omernik Level II Ecoregions. The summarized United States continental data includes USGS digital elevation, 30-year normal precipita tion and temperature, and 8 million AVHRR pixels classified into 159 types of land cover. One LM plot uses a line-height glyph to represent all 159 la nd cover percentages per ecoregion. LM plots represent new visualization me thodology that is useful in the data and knowledge based pattern representa tion and knowledge discovery process. The LM plots focus on providing an or ienting overview. The overview provides a starting place for subsequent dri lling down to what could otherwise be viewed as an overwhelming mass of dat a. The overview also provides a starting place to learn about the intellect ual structure that lies behind the notion of ecoregions and begins to conne ct this abstract structure to quantitative methods.