Localized correlation coefficient (r-values) between middle-to-high (≤680 mb/>3.2 km) and low (>680 mb/<3.2 km) level cloud from the (a) ISCCP IR and (b) MODIS datasets. Only statistically significant r-values (p < .05) are displayed. The data shows that for regions of frequent cloud cover the low level cloud is strongly anti-correlated to overlying cloud, indicating that variations in the low cloud are predominantly artificial.