Abstract:
The characteristics of the Mesoscale Convective Complex (MCC) from convective initiation to mature stage over the Sichuan Basin in 2018 were analyzed using high-frequency FY-4A satellite data. The results indicated that the area of MCC convective cloud increased at a rate of 0–50 pixels (15 min)
−1 at the convective–initiation stage and at 150–200 pixels (15 min)
−1 at the mature stage, finally reaching 7, 000–10, 000 pixels. The maximum temperature gradient is located on the side of the low-level inflow zone at the convective–initiation stage, which is concentrated near the 240 K contour with the most abundant texture in the cloud top, having a maximum value of 30°C–40°C. This feature basically disappears at the mature stage. The variation in the minimum infrared radiation 1 channel (IR1) and water vapor channel (IR3) at the convective–initiation and mature stages are consistent; both rapidly decrease to 190 K at the convective–initiation stage, while the minimum value remains unchanged at the mature stage. The distribution patterns of cloud top cooling rate (
R) of IR1 and IR3 are also similar. The significant
R, which is close to the 240 K on the side of the low-level inflow zone, reaches −40 K (15 min)
−1 at the convective–initiation stage but remains stable from −25 to −10 K (15 min)
−1 at the mature stage. The maximum brightness temperature difference (
D) is 6–10 K at the convective–initiation stage and 0~6 K at the mature stage. Moreover,
R(
D) in the low-level inflow zone is the most significant at the convective–initiation stage, remaining steady at the mature stage.