Simultaneous retrieval of land surface temperature and emissivity from the FengYun-4A advanced geosynchronous radiation imager

This paper extends a new temperature and emissivity separation(TES)algorithm for retrieving land surface temperature and emissivity(LST and LSE)to the Advanced Geosynchronous Radiation Imager(AGRI)onboard Fengyun-4A,China’s newest geostationary meteorological satellite.The extended TES algorithm was named the AGRI TES algorithm.The AGRI TES algorithm employs a modified water vapor scaling(WVS)method and a recalibrated empirical function over vegetated surfaces.In situ validation and cross-validation are utilized to investigate the accuracy of the retrieved LST and LSE.LST validation using the collected field measurements showed that the mean bias and RMSE of AGRI TES LST are 0.58 and 2.93 K in the daytime and−0.30 K and 2.18 K at nighttime,respectively;the AGRI official LST is systematically underestimated.Compared with the MODIS LST and LSE products(MYD21),the average bias and RMSE of AGRI TES LST are−0.26 K and 1.65 K,respectively.The AGRI TES LSE outperforms the AGRI official LSE in terms of accuracy and spatial integrity.This study demonstrates the good performance of the AGRI TES algorithm for the retrieval of high-quality LST and LSE,and the potential of the AGRI TES algorithm in producing operational LST and LSE products.

Spatiotemporal dynamic of environmental indices of watershed sustainability in connection with land-use change

Exploring spatial and temporal land-use changes is valuable for local governments to address issues of sustainability and planning policy where urbanization and industrialization are taking place.Besides anthropogenic effects,natural driving forces like climate change may also affect sustainability.However,such relationships have not been studied minutely.Hence,this study first investigates the land-use changes and their relationship with land surface temperature(LST)for the Shazand Watershed,Iran,in 1986,1998,2008,and 2016 coincided with supplementary industrialization stages.Furthermore,the relations among LST and other biophysical parameters,including Normalized Difference Vegetation Index(NDVI),Normalized Difference Buildup Index(NDBI),and Normalized Difference Water Index(NDWI),were analyzed,and corresponding variations were explored.The results indicated that the mean LST of the study watershed has an increasing trend from 1986 to 2008 due to land-use change and drought intensification.Later,LST decreased in 2016.Lower LST was associated with irrigation farming and orchard,and higher LST was related to sparse oak forest areas.There was also a negative correlation between LST and NDVI.As a result,it was inferred that greenery declined LST.Conversely,a positive correlation was found between LST and NDBI resulting from the built-up areas.Since LST could influence biological,physical,chemical processes,it can therefore be supported as an effective index for environmental sustainability assessment.