ISSN 1006-9895

CN 11-1768/O4

Using FY-2C High Temporal Resolution Regional Scan Data to Monitor Strong Convective Cloud
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    Abstract:

    The FY-2C geostationary satellite performed its first rapid regional scan test in 2011, yielding high temporal resolution data. The mean observation frequency is about 10 min. Observational test data were used to analyze a strong convective cloud development process that appeared on June 28-29, 2011, in Guangdong Province. The results show that the parameter difference between high-frequency observations can be used to monitor the initial development of convective clouds. The parameters can be selected as the brightness temperature at the infrared window channel and the brightness temperature difference between the infrared window channel and water vapor channel. At the initial phase of convective cloud formation, the cloud top first appeared strong cooling at the infrared window channel. Then, the brightness temperature difference between the infrared window and water vapor channels decreased, demonstrating that the height of the cloud top developed considerably. Accompanied by the development of convective clouds, the minimum brightness temperature continued to decrease, and the number of cold cloud pixels increased gradually, indicating that the cloud continued to develop. Hourly precipitation data at the surface are classified into three levels: smaller than 5 mm, between 5 mm and 10 mm, and larger than 10 mm. According to the different precipitation levels, the statistical distribution of the brightness temperature in the infrared window channel was analyzed. The results show that the cold cloud top is the main property producing strong precipitation during a strong convective cloud process. The colder the cloud top is, the stronger the precipitation is that appears on the surface. A Hovmöller diagram is used to show the evolving properties of the cloud cold core in high-frequency observation mode. Combined with hourly precipitation data, it can show good agreement between the location of the cold cloud core and the center of maximum precipitation. Because there are six observations during 1 h during the high-frequency rapid regional scan, the standard deviation in the brightness temperature is calculated. A smaller standard deviation in the brightness temperature during 1 h indicates fewer changes in the cloud top properties. When heavy precipitation appears on the surface, the cloud not only has a colder top temperature, but also the colder cloud top should remain for a certain time period. On the basis of the above analysis, a high-frequency rapid regional scan can capture the features of evolving convective cloud properties, providing technological support to forecast the initial stages of a convective cloud mass.

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History
  • Received:April 09,2012
  • Revised:November 16,2012
  • Adopted:
  • Online: June 18,2013
  • Published: