RGB combination
An artificial composite of the infrared and water vapour channels of FY-2 was provided by the RGB combination. The RGB combination consists of the IR12.0-IR10.7 Brightness Temperature Difference (BTD, on red), the IR10.7-IR3.9 BTD (on green) and the IR10.7 channel (on blue). The BTD of IR12.0-IR10.7 and IR10.7-IR3.9 were limited form -4K to 4K, and -90K to -10K respectively. Figure 17 is the RGB combination image and intensive convective cloud could been found easily. But there are a lots noise points in thickness cold cloudiness, just as several disperse pink points lied in the blue region in image. As soon as noise points were appeared, the convective cloud was not intensive any more and maybe die out in the following few hours.
Figure 17: FY-2 RGB combination at 07:00
Figure 18: FY-2 RGB combination at 07:00