Journal of Tropical Oceanography ›› 2019, Vol. 38 ›› Issue (6): 29-40.doi: 10.11978/2019003CSTR: 32234.14.2019003

• Marine Hydrography • Previous Articles     Next Articles

Analysis of characteristics of brightness temperature relative power spectrum before and after typhoon landfall in Guangdong coastal area

ZHANG Xin1, CHEN Mingyu2()   

  1. 1. Key Laboratory of Earthquake Monitoring and Disaster Reduction Technology, China Earthquake Administration, Guangdong Earthquake Agency, Guangzhou 510070, China
    2. Ocean College, Zhejiang University, Zhoushan 316021, China.
  • Received:2019-01-03 Revised:2019-04-18 Online:2019-11-20 Published:2019-11-26
  • Contact: Mingyu CHEN E-mail:chenmyu@zju.edu.cn
  • Supported by:
    Combination Project with Monitoring, Prediction and Scientific Research of Earthquake Technology, CEA(CEA3JH2017-0124);Earthquake Science and Technology Star Fire Plan(XH2018034Y)

Abstract:

In the period of 2008-2017, there were 25 typhoons that made landfall in the coastal areas of Guangdong, China. However, abnormal thermal radiation around the typhoon landing area has not attracted much attention so far. In this paper, the infrared remote sensing temperature data of Chinese geostationary meteorological satellite FY-2C/2E are used to analyze the thermal radiation anomalies associated with typhoon landfall. The temporal and spatial distributions of thermal radiation before and after typhoon landfall are quantified using bright temperature relative power spectrum (RPS). It is found that with the typhoon landfall, RPS was five times greater than the background value, experiencing a process of generating— increasing—reaching maximum—attenuating—extinction, which lasted longer than the typhoon process itself. There was a correlation between the area with enhanced RPS and typhoon landfall path, limited by terrestrial conditions and ocean heat supply. By analyzing the landfall path and RPS change trend during the typhoon landfall process, we show that the thermal radiation lasted for 10-20 days before and after typhoon landfall, and the thermal anomalies during this period were all related to the typhoon process. The mechanism of thermal radiation anomalies caused by typhoon landfall may be related to the heating leakage and water-vapor accumulation, that is, the ocean heat absorbed by typhoon is modulated by the air-sea interaction as the air rises, resulting in thermal radiation variation in different frequency bands and regions.

Key words: typhoon, landfall, relative power spectrum, coastal area of Guangdong province, thermal radiation