Study of Sea Level Rise Using Tide Gauge Data Year 1996 to 2015 at Semarang and Prigi Stations

Sea level rise monitoring using tide gauge data is done continously so that long period data is available. The objective of this research is to analyze sea level rise from long period tide gauge data. This research uses tide gauge data in Semarang and Prigi station period 1996 to 2015. Data processing is done using Matlab 2013b to plot sea level rise data and to calculate the the trend of sea level rise. Initial stage of data processing is quality control of tide gauge data by eliminating outlier data with confidence level of three sigmas and filled empty data with NaN (Not A Number). Shifting correction is done if there is reference bias at some period of data recording at a station. Processing followed by calculation of monthly MSL (Mean Sea Level) and SLR (Sea Level Rise) with linear regression to calculate trend value of sea level rise. The result of this research is at Semarang tidal station produces SLR 4,4 mm/year with SEE 0,1 mm. At Prigi station, SLR calculation is divided into three periods namely 1996 to 1999, 2002 to 2009 and 2010 to 2015 due to more than 1 year data vacuum. Data period 1996 to 1999 shows the falling in sea level about 10.2 mm/yr with SEE 0.3 mm, 2002 to 2009 data period produces sea level rise 25.5 mm/yr with SEE 0.2 mm, and 2010 to 2015 data period shows the falling in sea level about 0.07 mm/yr with SEE 0.08 mm. The conclusions of this study are the rise and fall of sea level influenced by EI Nino and La Nina phenomena and climate change.