In the current analysis the cocitation correlation matrix was mapped to two dimensions and the points plotted, as shown in Figure 3. The resulting map has been annotated to indicate some of the major ``topical'' clusters of WWW sites revealed by the cocitation analysis. This is just one interpretation of the information revealed by the MDS processing. In general, the vertical axis of Figure 3 seems to represent a topical continuum ranging from ``Weather and Climate'' related sites at the bottom to ``Geography and GIS'' related sites at the top. The horizontal axis appears to represent a continuum ranging from ``Remote Sensing'' related sited on the left to ``Ecology and Environment'' related sites on the right. Central to the mapping (indicating centrality in the field) are sites dealing with the Earth system and geophysical phenomena.
Of course, drawing the borders of the clusters revealed by MDS is strongly affected by the author's own biases, but the general meaning of the axes seems fairly clear. Sites such as Climate Prediction Center at NOAA (S14), NASA-Goddard Climate and Radiation Branch (S5), the NOAA/PMEL/TAO El Nino Theme Page (S30), and the NOAA ``Live Access to Climate Data'' site (S10), Weathernet (S4) and the ``Current Weather Maps/Movies'' site (S33) seem to form a natural and related cluster of topically similar WWW sites. Other sites that seem to be topically related are not so closely placed on the mapping. For example there seems to be line of hydrology and ocean-related sites (S29, S28, S17) that crosses several of the notional groups drawn on Figure 3. Perhaps adding a third dimension would show additional groupings not apparent in 2-d.
The mappings produced by cocitation analysis of WWW sites in Geographic Information Systems, Earth Sciences, and Satellite Remote Sensing seem to produce quite clear, reasonable and interpretable results.