Long-term and seasonal changes of the mean sea level at Syowa Station, Antarctica, from 1981 to 2000

• Main Authors: Michida,Yutaka, Tateoka,Atsushi, Kinoshita,Hideki, Namiki,Masaharu, Odamaki,Minoru
• Format: Report
• Language: English
• Published: Ocean Research Institute, The University of Tokyo/Ocean Research Institute, The University of Tokyo/Hydrographic Department, Japan Coast Guard/Hydrographic Department, Japan Coast Guard/Hydrographic Department, Japan Coast Guard 2004
• Subjects: Antarctic; sea level; tide; long-term trend; seasonal change; Syowa Station; Ongul; Ongul Island; East Ongul Island; Antarc*; Antarctica; Polar meteorology and glaciology
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=2970; http://id.nii.ac.jp/1291/00002970/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=2970&item_no=1&attribute_id=18&file_no=1

Sea level has been observed since 1966 at Syowa Station, a Japanese Antarctic station located on East Ongul Island(39.6°E , 69.0°S ). An almost continuous record has been obtained from 1981 to 2000 and analyzed to investigate long-term and seasonal changes of mean sea level. After correction of year-to-year variation of the datum, it is found that the annual mean sea level has been falling at a rate of 1.2cm/year. This rate is bigger than previous estimations calculated from shorter records of sea level without appropriate datum adjustment, and also bigger than that expected from geological evidence. Based on discussion of the reasons for the trend, it is suggested that glacial rebound can not be excluded as the cause. The present analysis based on a long record for about 20years also provides the amplitude(2.7cm) and phase of the nodal tide with the period of 18.6years. Characteristics of the seasonal change for the first half of the record(1981-1989) are different from those for the second half(1990-2000), associated with replacement of the observing system in 1990. Comparing with seasonal changes at other Antarctic stations and considering the results of previous studies, it is concluded that the seasonal change observed in the second half is more reliable, and that it reaches its maximum in April and minimum in October with an estimated annual tidal range of about 14cm.