A Modified Approach of Extracting Landfast Ice Edge Based on Sentinel-1A InSAR Coherence Image in the Gulf of Bothnia

Abstract

Landfast ice is an integral component of the coastal ecosystem. Extracting the edge and mapping the extent of landfast ice are one of the main methods for studying ice changes. In this work, a standardized process for extracting landfast ice edge in the Baltic Sea using the InSAR coherence image is established with Sentinel-1 radar data and InSAR technology. A modified approach combining multiscale segmentation and morphological erosion is then proposed to provide a reliable way to extract landfast ice edge. Firstly, the coherence image is obtained using InSAR technology. Then, the edge is separated and extracted with the modified approach. The modified approach is essentially a four-step procedure involving image segmentation, median filter, morphological erosion, and rejection of small patches. Finally, the full extent of landfast ice can be obtained using floodfill algorithm. Multiple InSAR image pairs of Sentinel-1A acquired from 2018 to 2019 are utilized to successfully extract the landfast ice edge in the Gulf of Bothnia. The results show that the landfast ice edge and the extents obtained by the proposed approach are visually consistent with those shown in the ice chart issued by the Swedish Meteorological and Hydrological Institute (SMHI) over a coastline length of 345 km. The mean distance between land–water boundary and the coastline issued by the National Oceanic and Atmospheric Administration (NOAA) is 109.1 m. The modified approach obviously preserves more details in local edge than the reference method. The experimental results show that the modified approach proposed in this paper can extract the edge and map the extent of landfast ice more accurately and quickly, and is therefore expected to contribute to the further understanding and analyzing the changes of landfast ice in the future.

Extracting winter wheat based on multi-feature optimization of short-time series synthetic aperture radar data with dual polarizations

“…On the contrary, if the scattering medium is changed significantly, it will be significantly reduced. For Sentinel-1A SLC data with VV/VH polarization, interferometric SAR (InSAR) was performed on every two scenes with adjacent dates 44 . In this process, the image before the date was the master image and the image after the date was the slave image, with a temporal baseline of interferometric pairs were 36 days in the paper.…”

“…For Sentinel-1A SLC data with VV/VH polarization, interferometric SAR (InSAR) was performed on every two scenes with adjacent dates. 44 In this process, the image before the date was the master image and the image after the date was the slave image, with a temporal baseline of interferometric pairs were 36 days in the paper. The calculation of the coherence coefficient is based on the following equation: 45…”

Research on weed identification method in rice fields based on UAV remote sensing

“…By competing with rice for water, fertilizer, light, and space, they change the microecological environment of paddy fields, affect the photosynthesis, nutrition, and reproductive growth of rice, and are intermediate hosts of pests and diseases, aggravating the occurrence of pests and diseases, leading to yield reduction and decline of rice quality, and causing huge losses to rice production ( Luo et al., 2020 ). In the current rice weed management process, chemical weed control is currently the most effective and widely used method of weed control in rice fields, commonly used to spray herbicides uniformly and covering the entire operating area in a disorderly “spot” or “sheet” form ( Eppinga et al., 2020 ; Druskin et al., 2021 ; Wang et al., 2021 ). The presence of weeds can lead to excessive spraying of herbicides ( Siva Kumar et al., 2020 ; Su et al., 2022 ).…”