Using Linked Micromap Plots to Characterize Omernik Ecoregions

The paper introduces linked micromap (LM) plots for presenting environmental 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 precipitation 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 land cover percentages per ecoregion. LM plots represent new visualization methodology that is useful in the data and knowledge based pattern representation and knowledge discovery process. The LM plots focus on providing an orienting overview. The overview provides a starting place for subsequent drilling down to what could otherwise be viewed as an overwhelming mass of data. The overview also provides a starting place to learn about the intellectual structure that lies behind the notion of ecoregions and begins to connect this abstract structure to quantitative methods.