A study of sea ice regime in the Obskaya guba Bay using modern satellite data in 2007–2017

Abstract

The Obskay guba Bay is a region of rapidly developing oil and gas exploration. Knowing the current sea ice conditions including dangerous phenomena e. g. ridges and stamukhas is important for the safety of coastal and underwater construction as well as for ecological risk assessment. With this study, we aim to obtain new data on sea ice seasonal cycle in the southern and central part of the Obskay guba Bay for 10 years (from 2007 to 2017) and to demonstrate the capacity of satellite data in obtaining varying sea ice characteristics in the region. Analyzing daily visual MODIS and available Sentinel-1 SAR imagery, we derived dates of sea ice and fast ice formation, fast ice breakup and melt onset and the onset of ice-free period. For this purpose the satellite data were analyzed manually by sea ice expert. In addition, of sea ice ridges were derived and the sea ice drift data wea automatically processed in order to locate motionless sea ice features — stamukhas. The distribution of sea ice floes and field size in the region was derived from MODIS data. The analysis showed that there is a tendency towards a shorter ice covered period based on the data from 2007 to 2017. Overall, the formation of sea ice starts 9 days later and fast ice breakup occurs 16 days earlier compared to the long-term mean (1947–2010). The majority of ridges were located in the central part of the region and directed along the coast. The analysis confirmed absence of large stamuhas visible to be applied method (with a horizontal size of 100 m). The predominant sea ice field size range lies 500–1500 m. The study shows that a combination of images obtained in the optical range of the survey with radar data makes it possible to supplement the classical visual assessments with the results of automatic methods for detecting fast ice, detecting stamukha, as well as ice drift and deformation.