FIGURE T25. Mean (top) and anomalous (bottom) outgoing longwave radiation  (NOAA 18 AVHRR IR window channel measurements by NESDIS/ORA). OLR contour interval is 20 Wm^-2 with values greater than 280 Wm^-2 indicated by dashed contours. Anomaly contour interval is 15 Wm^-2 with positive values indicated by dashed contours and light shading. Anomalies are departures from the 1979–95 base period monthly means.