186SL0728110101301 321A 19831218 19931231 0128N 10348E 2 00000R 0000 MM 186SL0728210101301 Johor Baharu Malaysia Dept. of Survey and Mapping 186SL072830001 186SL072830002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL072830003 by the 186SL072830004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL072830005 JOINT ARCHIVE FOR SEA LEVEL 186SL072830006 186SL072830007Station : Johor Baharu Latitude: 01 27.7N 186SL072830008Country : Malaysia Longitude: 103 47.5E 186SL072830009JASL # : 321A Time Meridian: 120E (GMT + 8 hr) 186SL072830010GLOSS # : none TOGA #: none NODC #: 10101301 186SL072830011Contributor : Dept. of Survey and Mapping 186SL072830012 Jalan Gurney 186SL072830013 50578 Kuala Lumpur, Malaysia 186SL072830014Originator : same 186SL072830015Original Data: digital; samples taken every 10 sec; 50 sec average 186SL072830016Instrmnt Type: Magnetic Tape Type Tide Gauge, Model LLT- 186SL072830017 3AD (Kyowa Shoko Co. LTD, Japan) 186SL072830018Digitzd Intvl: one hour 186SL072830019Present Data : Hourly, daily, and monthly values obtained by: 186SL072830020 Hourly : Five-point least squares approximation (more 186SL072830021 information available from the address above) 186SL072830022 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL072830023 centered on noon applied to the hourly data 186SL072830024 with respective periods of the 95, 50, and 5% 186SL072830025 amplitude points at 124.0, 60.2, and 40.2 hours 186SL072830026 Monthly: Simple average of all daily values; calculated if 186SL072830027 7 or fewer days are missing 186SL072830028Span of data : 18 Dec 1983 - 31 Dec 1993 186SL072830029Gaps > 1 mon : 30 Jun 1989 - 02 Aug 1989 186SL072830030Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 186SL072830031Units : millimeters Missing Data Flag :99999 186SL072830032Refernce Levl: The sea level heights are referred to the zero 186SL072830033 point assigned to the tide gauge. Bench mark 186SL072830034 information is available upon request from the 186SL072830035 contributors. 186SL072830036Comment : The residual series are very noisy which is 186SL072830037 probably due to shallow water tides that are not 186SL072830038 resolved by the harmonic analysis. The daily and 186SL072830039 monthly means of J. Baharu agree with Kuantan. 186SL072830040 No reference level shifts are apparent. 186SL072830041 186SL072830042 CI MISSING REPLACED GAPS QUESTIONABLE 186SL072830043YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL072830044---- --- -------------------- --------------- -------------------- 186SL0728300451983 4 none none see comment above 186SL0728300461984 89 50-68,232-254 none " " " 186SL0728300471985 80 100-108,114-133, none " " " 186SL072830048 277-319 186SL0728300491986 96 292-299,305-309 none " " " 186SL0728300501987 100 none none " " " 186SL0728300511988 100 none none " " " 186SL0728300521989 91 181-214 none " " " 186SL0728300531990 100 none none " " " 186SL0728300541991 100 none none " " " 186SL0728300551992 100 none none " " " 186SL0728300561993 94 73-96 none " " " 186SL072830057 186SL072830058 QUALITY ASSESSMENT POLICY 186SL072830059 186SL072830060 The quality assessment is mostly based on the residuals 186SL072830061 (observed data minus predicted tides) of the hourly data. This 186SL072830062 assessment also applies to the daily and monthly data since 186SL072830063 they were derived from the quality-controlled hourly data. 186SL072830064 186SL072830065 The following abbreviations are used in the assessment: 186SL072830066 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL072830067 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL072830068 research program; NODC - National Oceanographic Data Center; 186SL072830069 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL072830070 Gaps > 1 mon - missing data in a span greater than one month; 186SL072830071 Refernce - reference. 186SL072830072 186SL072830073 The following corrections are made to the hourly data 186SL072830074 prior to this assessment: 186SL072830075 1) Gaps or obviously wrong data points in a span less than 186SL072830076 25 hours are filled by the predicted tide method*. 186SL072830077 2) Timing errors of exact increments of an hour are corrected 186SL072830078 by shifting the data. 186SL072830079 3) Reference level shifts are only corrected after information 186SL072830080 from tide staff readings or comparative readings with a fixed 186SL072830081 bench mark are checked to verify that the shift was not a 186SL072830082 natural event. If comparative readings are missing or 186SL072830083 incomplete, comparisons of the data with nearby stations 186SL072830084 may warrant the adjustment of some obvious shifts. 186SL072830085 4) Data with unresolved datum shifts are not disseminated. 186SL072830086 However, if sufficient time spans of data are available before 186SL072830087 or after the year(s) with the unresolved shift(s), a subset of 186SL072830088 quality assured data is made available. Thus, the Span field 186SL072830089 in the Quality Assessment may not match the span of the 186SL072830090 distribution data set. As the questionable datum shifts are 186SL072830091 resolved, the data set will be updated. Although this policy 186SL072830092 adds some complexity, it allows more rapid dissemination of 186SL072830093 at least the quality assured years. 186SL072830094 186SL072830095 For each year, the following information is documented from 186SL072830096 the quality-controlled hourly data with dates given as the nth 186SL072830097 day of the year starting from 1 January: 186SL072830098 1) a Completeness Index (CI) based on the percentage of hours 186SL072830099 with available data, 186SL072830100 2) a list of gaps longer than a day, 186SL072830101 3) a summary of days with consecutive missing or obviously 186SL072830102 wrong data in a time span longer than 6 but less than 25 186SL072830103 hours that have been replaced, with hours in parentheses, and 186SL072830104 4) a summary of days with questionable fluctuations in the 186SL072830105 residual series. Fluctuations within the residuals are 186SL072830106 considered significant and are noted if they are greater than 186SL072830107 25 cm. This policy has changed slightly as of October 1992: 186SL072830108 only suspicious fluctuations due to obvious instrumentation 186SL072830109 problems are noted. Minor timing drifts are no longer 186SL072830110 included in the list of questionable days. 186SL072830111 186SL072830112 Note : If the predicted tides poorly model the observed heights 186SL072830113 due to the inability of the tidal analysis to completely resolv 186SL072830114 the non-linear shallow water effects, the residuals are not 186SL072830115 suitable for assessing the data quality. Instead, a subjective 186SL072830116 comment on the quality of the data is provided. 186SL072830117 186SL072830118 *The predicted tides are obtained with the use of a harmonic 186SL072830119 analysis program (Foreman, 1977) which is executed on a year 186SL072830120 of apparently good data for a given station. The Predicted 186SL072830121 Tide Method for filling gaps consists of statistically 186SL072830122 comparing the predicted tides to the observed data and 186SL072830123 shifting the predicted tides in time to correct for timing 186SL072830124 differences. Then the linear interpolation between hourly 186SL072830125 values at the end points of the gap in the residual series is 186SL072830126 added to the corresponding corrected predicted tide data to 186SL072830127 obtain interpolated values over the span of the gap. 186SL072830128 186SL072830129 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL072830130 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL072830131 186SL072830132 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL072830133 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL072830134 Victoria B.C. Pacific Marine Science Report 77-10. 186SL072830135 186SL07286 19831 999999999999999999999999999999999999999999999999 186SL07286 19832 999999999999999999999999999999999999999999999999 186SL07286 19841 30130009999999999999999 2781000 2784000 2731000 186SL07286 19842 27470009999999999999999 2864000 2962000 2993000 186SL07286 19851 2928000 2880000 29280009999999999999999 2710000 186SL07286 19852 2734000 2718000 27790009999999999999999 2971000 186SL07286 19861 3019000 2867000 2899000 2797000 2732000 2726000 186SL07286 19862 2706000 2718000 276900099999999 2949050 2967000 186SL07286 19871 2974000 2865000 2780000 2766000 2733000 2719000 186SL07286 19872 2707000 2738000 2752000 2836000 2873000 3097000 186SL07286 19881 2946000 2902000 2882000 2835000 2741000 2737000 186SL07286 19882 2753000 2762000 2787000 2869000 3052000 3002000 186SL07286 19891 2980000 2908000 2874000 2747000 2771000 2728010 186SL07286 19892 99999999 2745020 2791000 2900000 3003000 3007000 186SL07286 19901 2970000 2911000 2845000 2804000 2774000 2706000 186SL07286 19902 2677000 2693000 2775000 2846000 2894000 2985000 186SL07286 19911 2945000 2917000 2826000 2816000 2777000 2716000 186SL07286 19912 2683000 2706000 2765000 2888000 2971000 2989000 186SL07286 19921 2970000 2848000 2820000 2775000 2761000 2719000 186SL07286 19922 2740000 2717000 2757000 2897000 3002000 2965000 186SL07286 19931 2971000 286800099999999 2816060 2747000 2691000 186SL07286 19932 2713000 2725000 2776000 2879000 2931000 3050000