Why does the data have the appearance of a slight north-south pattern?
A7. The surface wetness and temperature anomaly data are generated by Commodity Hedgers, Inc. in Geographic coordinates (latitude/longitude). This coordinate system is spherical and is suitable for displaying data for the entire world. However, when data over Canada is displayed in Geographic coordinates, the shape of the country is truncated in north-south direction. To optimize the appearance and be consistent with other Drought Watch maps, the data are converted into a Lambert Conformal Conic projection, which essentially stretches out the map in north-south direction to give it a more representative shape. As a result, the individual data pixels, or grid cells, are also stretched in north-south direction. In other words, the data pixels were originally square, but have been stretched out by re-projection and are rectangular in the final map product. This is the reason for the appearance of a north-south pattern in the data.
