On-site high-resolution sea ice images from the imaging instruments on airplane, helicopter, ship and unmanned aerial
vehicle (UAV) platforms have been used as the reference datasets for validation of the sea ice properties. Among the low
altitude remote sensing platforms, helicopters usually carried onboard icebreakers for scientific research activities and
logistics have been recognized as a reliable remote sensing platform from enhanced endurance and verified stability, and
have flexibility for the attachment of multiple sensors. Although areal reference datasets, e.g., helicopter-borne high-resolution
images, can be used to validate lower resolution sea ice information from the characteristics of enough
coverage and fine spatial resolution, continuous drift of sea ice causes distorted locations of image acquisition along the
drift; thus, becomes an obstacle for precise image mosaicking and matching with the sea ice information extracted from
lower-resolution remote sensing imagery. This study presents methods for the cost-effective acquisition of helicopterborne
high-resolution images over drifting Arctic sea ice using a simple configuration of imaging sensor and GPS logger,
and for the compensation of the effect from sea ice drift from each imaging location using the drift trajectory of sea ice.
After mosaicking the sea ice drift compensated high-resolution helicopter-borne images with structure-from-motion
technique, the applicability of the mosaicked image was assessed by comparing with lower resolution satellite synthetic
aperture radar image. The results suggest that the proposed methods can be applicable to the high-resolution images from
other low altitude remote sensing platforms, e.g., UAVs, and can be used for precise comparison with various sea ice
products from satellite remote sensing.
Sea ice is an important factor for understanding Antarctic climate change. Especially, annual change of sea ice shows different trend in Antarctica and Arctic. This different variation need to continuously observe the Polar Regions. Sea Ice Albedo (SIA) and Sea Ice Concentration (SIC) are an indicator of variation on sea ice. In addition, albedo is key parameter to understand the energy budget in Antarctica. This being so, it is important to analyze long-term variation of the two factors for observing of change of Antarctic environment. In this study, we analyzed long-term variability of SIC and SIA to understand the changes of sea ice over Antarctic and researched the relationship with two factors. We used the SIA data at The Satellite Application Facility on Climate Monitoring (CM SAF) and the SIC data provided by Ocean and Sea Ice Satellite Application Facility (OSI-SAF) from 1982 to 2009. The study period was selected to Antarctic summer season due to polar nights. We divided study periods into two terms, Nov-Dec(ND) and Jan-Feb(JF) in order to reflect the characteristics of sea ice area, which minimum extend occurred in September and maximum extend occurred in February. We analyzed the correlation between SIA and SIC. As a results, two variables have a strong positive correlation (each correlation coefficients are 0.91 in Nov-Dec and 0.90 in Jan-Feb). We performed time series analysis using linear regression to understand the spatial and temporal tendency of SIA and SIC. As a results, SIA and SIC have a same spatial trend such as Weddle sea and Ross sea sections show the positive trend and Bellingshausen Amundsen sea shows the negative trend of two factors. Moreover, annual SIA change rate is 0.26% ~ 0.04% yr-1 over section where represent positive trend during two study periods. And annual SIA change rate is - 0.14 ~ - 0.25 % yr-1 of in the other part where represent negative trend during two study periods.