# Satellite-Based Sea Ice Navigation for Prydz Bay, East Antarctica
## 6 Conclusions and Recommendations  
This study presents a system, called SatSINS, for using a suite of remote sensing data to devise a proposed nautical route for vessel navigation through sea ice cover in the Southern Ocean. This task was undertaken because of the lack of a regulatory ship navigation system in the Antarctic waters (unlike Arctic waters) and the limited availability of ice information there. The system is presented in the context of a decision-making process to support the routing of the Chinese RV _Xuelong_ during her passage through Prydz Bay. We demonstrated that different remote sensing and meteorological data sources and products play diverse roles in providing sea ice information at different spatial and temporal scales. A few factors that contribute to the gap between demand and supply data for nautical ice navigation are discussed. Our study has presented how such gap can be narrowed, underlining the importance of case studies to provide guidance on how to best chain a suite of satellite data for the use of nautical ice navigation. Discussions of navigation parameters that meet conditions of geophysical processes that impede ship navigation are presented. Coarse-resolution data including SIC maps and medium resolution optical imagery provide synoptic scale ice information. This information is used to delineate the ice edge and synoptic features of the ice field. If large-scale ice concentration is less than 70% then only SIC and optical data (e.g., from MODIS) are sufficient to develop a proposed nautical route. Otherwise, fine-resolution SAR data should be analyzed to identify ice features that should be avoided (e.g., thick and ridged ice zones) and features that should be included in the proposed route (e.g., leads and thin ice). Atmospheric forecast data of MSLP and near surface wind should be examined in both cases to assess the severity of ice conditions and therefore the need for inclusion of SAR data (only if SIC > 70%). The information on cyclone systems (initial location, development, and movement routes) was vital for RV _Xuelong_'s navigation. In this study the closest available satellite data to the actual location of the vessel were lagging by one day. In most cases that was sufficient but the proposed route may have to be adjusted based on observations of the surrounding ice from the ship. To assess the performance of the proposed routing, we calculated the deviation of the actual trajectory of the vessel from the proposed route. For the 28 th CHINARE2011, the maximum deviation was nearly 7 km and for the 30 th CHINARE2013 the average deviation was 3.5 km. This is consistent with possible ice redistribution caused by its mobility. When the major part of the vessel's route was covered by thin ice in a polynya (29 th CHINARE2012) the vessel was advised to travel within a proposed meridional band rather than along specific waypoints. The parameters needed to develop the vessel route in ice-covered water include SIC, SIT, ice-type distribution, and ice deformation (triggered by ice motion). While ice concentration is readily available at a coarse resolution, ice type and surface deformation are usually retrieved subjectively through visual image analysis, particularly of SAR data. Ice thickness is the most difficult parameter to estimate, especially after the ice grows beyond a few weeks. This is particularly true in the case of land-fast ice because this ice has a wide range of thickness. The slowest speed experienced by [PERSON][PERSON]_'s was during her navigation in the land-fast ice near Zhongshan Station. Thickness of this ice was calculated using a simple thermodynamic model and air temperature available from an existing meteorological station. Accurate estimates of sea ice thickness on a short time scale from remote sensing to satisfy navigational requirements still need considerable improvement.