Probabilities of acquiring cloud-free and low-tide Landsat observations for mapping saltmarsh over south-eastern Bangladesh from 1980 to 2019

Abstract As is well-documented, cloud cover (CC) obscures the target object and water depth and turbidity impede optical remote sensing (RS). Therefore, Landsat imagery acquired under cloud-free (CFI) and low-tide (LTI) conditions are considered ‘quality’ observations when mapping tidal wetlands such as saltmarsh. Although it is essential to estimate probabilities of acquiring at least one CFI and LTI, previous studies rarely addressed in RS of saltmarsh land cover (SLC). In order to evaluate the probabilities of acquiring at least one CFI and LTI in a year, a month, a season, a pair of seasons, or a certain time interval within a year over south-eastern Bangladesh, all images acquired between 1988 and 2019 were examined. The results indicate that SLC applications are generally affected by CC and tide heights; an average yearly CF probability of 16% can be acquired under LT conditions. Seasonal variations in CFI are apparent and there is a significant shortage of clear observation during the monsoon. The higher number of CFI may not guarantee a higher probability of LTI due to tide dynamics. The availability of both CFI and LTI can be remarkably improved if the present 16-day interval time of Landsat’s acquisition is increased.