Change assessment of the Tonga island surface temperature before and after volcanic eruption based on FY-3D time series dataset

Taking advantage of the 250 m resolution and daily observation of dual thermal infrared channels data of the Medium Resolution Spectral Imager (MERSI) onboard the Fengyun 3D (FY-3D) satellite, a refined thermal infrared island surface temperature (ILST) inversion model is established through radiation transmission simulation. And the Tonga ILST change maps before and after the volcanic eruption are produced and analyzed based on ILST time series dataset. The results show that the ILST decreases by 2 K –3 K within the five days after the eruption due to the amount of volcanic ash deposition, but increases significantly by 2 K –6 K within the fifth to tenth days after the eruption. The trend of time-limited cooling, warming, and then gradual recovery after volcanic eruption is very obvious. Through the manual cleaning and the scouring by seawater or rainwater to the volcanic ash covered ground, more parts of the island surface restored its original state. Hence, the Tonga ILST also increased gradually within a week thereafter. However, in regions with local vegetation, the recovery time of ILST would be longer. The temporal and spatial resolution of FY-3D MERSI meets the need for monitoring the changes of the island surface states before and after the volcanic eruption.