186SL0793110102201 141A 19841105 19931231 0213N 10209E 2 00000R 0000 MM 186SL0793210102201 Keling Malaysia Dept. of Survey and Mapping 186SL079330001 186SL079330002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL079330003 by the 186SL079330004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL079330005 JOINT ARCHIVE FOR SEA LEVEL 186SL079330006 186SL079330007Station : Keling Latitude: 02 12.9N 186SL079330008Country : Malaysia Longitude: 102 09.2E 186SL079330009JASL # : 141A Time Meridian: 120E (GMT + 8 hr) 186SL079330010GLOSS # : none TOGA #: none NODC #: 10102201 186SL079330011Contributor : Dept. of Survey and Mapping 186SL079330012 Jalan Gurney 186SL079330013 50578 Kuala Lumpur, Malaysia 186SL079330014Originator : same 186SL079330015Original Data: digital; samples taken every 10 sec; 50 sec average 186SL079330016Instrmnt Type: Magnetic Tape Type Tide Gauge, Model LLT- 186SL079330017 3AD (Kyowa Shoko Co. LTD, Japan) 186SL079330018Digitzd Intvl: one hour 186SL079330019Present Data : Hourly, daily, and monthly values obtained by: 186SL079330020 Hourly : Five-point least squares approximation (more 186SL079330021 information available from the address above) 186SL079330022 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL079330023 centered on noon applied to the hourly data 186SL079330024 with respective periods of the 95, 50, and 5% 186SL079330025 amplitude points at 124.0, 60.2, and 40.2 hours 186SL079330026 Monthly: Simple average of all daily values; calculated if 186SL079330027 7 or fewer days are missing 186SL079330028Span of data : 05 Nov 1984 - 31 Dec 1993 186SL079330029Gaps > 1 mon : none 186SL079330030Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 186SL079330031Units : millimeters Missing Data Flag :99999 186SL079330032Refernce Levl: The sea level heights are referred to the zero 186SL079330033 point assigned to the tide gauge. Bench mark 186SL079330034 information is available upon request from the 186SL079330035 contributors. 186SL079330036Comment : The residual series contain fluctionations with 186SL079330037 frequencies near the diurnal and semi-diurnal 186SL079330038 modes; these are probably due to shallow water 186SL079330039 tides that are not resolved by the harmonic 186SL079330040 analysis. The daily and monthly means of Keling 186SL079330041 and neighboring stations, Keling and Lumut, agree 186SL079330042 very well and no obvious reference level shifts or 186SL079330043 trends are apparent. 186SL079330044 186SL079330045 186SL079330046 CI MISSING REPLACED GAPS QUESTIONABLE 186SL079330047YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL079330048---- --- -------------------- --------------- -------------------- 186SL0793300491984 13 none none see comment above 186SL0793300501985 100 none none " " " 186SL0793300511986 100 none none " " " 186SL0793300521987 100 none none " " " 186SL0793300531988 100 none none " " " 186SL0793300541989 97 289-300 none " " " 186SL0793300551990 100 none none " " " 186SL0793300561991 97 301-303,314-325 (05)297-(12)297 " " " 186SL079330057 (15)304-(05)305 186SL079330058 (21)307-(05)308 186SL079330059 (23)309-(10)310 186SL079330060 (11)312-(03)313 186SL0793300611992 97 50-61 none " " " 186SL0793300621993 99 75-77 none " " " 186SL079330063 186SL079330064 QUALITY ASSESSMENT POLICY 186SL079330065 186SL079330066 The quality assessment is mostly based on the residuals 186SL079330067 (observed data minus predicted tides) of the hourly data. This 186SL079330068 assessment also applies to the daily and monthly data since 186SL079330069 they were derived from the quality-controlled hourly data. 186SL079330070 186SL079330071 The following abbreviations are used in the assessment: 186SL079330072 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL079330073 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL079330074 research program; NODC - National Oceanographic Data Center; 186SL079330075 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL079330076 Gaps > 1 mon - missing data in a span greater than one month; 186SL079330077 Refernce - reference. 186SL079330078 186SL079330079 The following corrections are made to the hourly data 186SL079330080 prior to this assessment: 186SL079330081 1) Gaps or obviously wrong data points in a span less than 186SL079330082 25 hours are filled by the predicted tide method*. 186SL079330083 2) Timing errors of exact increments of an hour are corrected 186SL079330084 by shifting the data. 186SL079330085 3) Reference level shifts are only corrected after information 186SL079330086 from tide staff readings or comparative readings with a fixed 186SL079330087 bench mark are checked to verify that the shift was not a 186SL079330088 natural event. If comparative readings are missing or 186SL079330089 incomplete, comparisons of the data with nearby stations 186SL079330090 may warrant the adjustment of some obvious shifts. 186SL079330091 4) Data with unresolved datum shifts are not disseminated. 186SL079330092 However, if sufficient time spans of data are available before 186SL079330093 or after the year(s) with the unresolved shift(s), a subset of 186SL079330094 quality assured data is made available. Thus, the Span field 186SL079330095 in the Quality Assessment may not match the span of the 186SL079330096 distribution data set. As the questionable datum shifts are 186SL079330097 resolved, the data set will be updated. Although this policy 186SL079330098 adds some complexity, it allows more rapid dissemination of 186SL079330099 at least the quality assured years. 186SL079330100 186SL079330101 For each year, the following information is documented from 186SL079330102 the quality-controlled hourly data with dates given as the nth 186SL079330103 day of the year starting from 1 January: 186SL079330104 1) a Completeness Index (CI) based on the percentage of hours 186SL079330105 with available data, 186SL079330106 2) a list of gaps longer than a day, 186SL079330107 3) a summary of days with consecutive missing or obviously 186SL079330108 wrong data in a time span longer than 6 but less than 25 186SL079330109 hours that have been replaced, with hours in parentheses, and 186SL079330110 4) a summary of days with questionable fluctuations in the 186SL079330111 residual series. Fluctuations within the residuals are 186SL079330112 considered significant and are noted if they are greater than 186SL079330113 25 cm. This policy has changed slightly as of October 1992: 186SL079330114 only suspicious fluctuations due to obvious instrumentation 186SL079330115 problems are noted. Minor timing drifts are no longer 186SL079330116 included in the list of questionable days. 186SL079330117 186SL079330118 Note : If the predicted tides poorly model the observed heights 186SL079330119 due to the inability of the tidal analysis to completely resolv 186SL079330120 the non-linear shallow water effects, the residuals are not 186SL079330121 suitable for assessing the data quality. Instead, a subjective 186SL079330122 comment on the quality of the data is provided. 186SL079330123 186SL079330124 *The predicted tides are obtained with the use of a harmonic 186SL079330125 analysis program (Foreman, 1977) which is executed on a year 186SL079330126 of apparently good data for a given station. The Predicted 186SL079330127 Tide Method for filling gaps consists of statistically 186SL079330128 comparing the predicted tides to the observed data and 186SL079330129 shifting the predicted tides in time to correct for timing 186SL079330130 differences. Then the linear interpolation between hourly 186SL079330131 values at the end points of the gap in the residual series is 186SL079330132 added to the corresponding corrected predicted tide data to 186SL079330133 obtain interpolated values over the span of the gap. 186SL079330134 186SL079330135 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL079330136 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL079330137 186SL079330138 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL079330139 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL079330140 Victoria B.C. Pacific Marine Science Report 77-10. 186SL079330141 186SL07936 19841 999999999999999999999999999999999999999999999999 186SL07936 19842 99999999999999999999999999999999 2908060 2908000 186SL07936 19851 2784000 2808000 2827000 2824000 2872000 2945000 186SL07936 19852 2883000 2833000 2858000 2938000 2941000 2894000 186SL07936 19861 2809000 2734000 2756000 2813000 2856000 2843000 186SL07936 19862 2866000 2888000 2851000 2904000 2960000 2779000 186SL07936 19871 2736000 2717000 2671000 2711000 2802000 2831000 186SL07936 19872 2867000 2810000 2788000 2837000 2977000 2983000 186SL07936 19881 2830000 2804000 2786000 2827000 2899000 2898000 186SL07936 19882 2832000 2843000 2836000 2962000 3036000 2906000 186SL07936 19891 2828000 2778000 2791000 2811000 2912000 2897000 186SL07936 19892 2880000 2853000 285200099999999 2980000 2818000 186SL07936 19901 2785000 2717000 2712000 2827000 2886000 2886000 186SL07936 19902 2808000 2865000 2853000 2884000 2935000 2839000 186SL07936 19911 2775000 2764000 2736000 2814000 2834000 2851000 186SL07936 19912 2797000 2773000 2827000 287202099999999 2832000 186SL07936 19921 275700099999999 2712000 2769000 2873000 2890000 186SL07936 19922 2861000 2857000 2856000 2968000 2936000 2876000 186SL07936 19931 2780000 2715000 2741030 2817000 2843000 2854000 186SL07936 19932 2853000 2871000 2848000 2930000 2945000 2967000