186SL0795110105001 144A 19841115 19931231 0525N 10021E 2 00000R 0000 MM 186SL0795210105001 Penang Malaysia Dept. of Survey and Mapping 186SL079530001 186SL079530002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL079530003 by the 186SL079530004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL079530005 JOINT ARCHIVE FOR SEA LEVEL 186SL079530006 186SL079530007Station : Penang Latitude: 05 25.3N 186SL079530008Country : Malaysia Longitude: 100 20.8E 186SL079530009JASL # : 144A Time Meridian: 120E (GMT + 8 hr) 186SL079530010GLOSS # : none TOGA #: none NODC #: 10105001 186SL079530011Contributor : Dept. of Survey and Mapping 186SL079530012 Jalan Gurney 186SL079530013 50578 Kuala Lumpur, Malaysia 186SL079530014Originator : same 186SL079530015Original Data: digital; samples taken every 10 sec; 50 sec average 186SL079530016Instrmnt Type: Magnetic Tape Type Tide Gauge, Model LLT- 186SL079530017 3AD (Kyowa Shoko Co. LTD, Japan) 186SL079530018Digitzd Intvl: one hour 186SL079530019Present Data : Hourly, daily, and monthly values obtained by: 186SL079530020 Hourly : Five-point least squares approximation (more 186SL079530021 information available from the address above) 186SL079530022 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL079530023 centered on noon applied to the hourly data 186SL079530024 with respective periods of the 95, 50, and 5% 186SL079530025 amplitude points at 124.0, 60.2, and 40.2 hours 186SL079530026 Monthly: Simple average of all daily values; calculated if 186SL079530027 7 or fewer days are missing 186SL079530028Span of data : 15 Nov 1984 - 31 Dec 1993 186SL079530029Gaps > 1 mon : none 186SL079530030Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 186SL079530031Units : millimeters Missing Data Flag :99999 186SL079530032Refernce Levl: The sea level heights are referred to the zero 186SL079530033 point assigned to the tide gauge. Bench mark 186SL079530034 information is available upon request from the 186SL079530035 contributors. 186SL079530036Comment : The daily and monthly means of Penang and an 186SL079530037 adjacent station, Lumut, agree very well. 186SL079530038 186SL079530039 CI MISSING REPLACED GAPS QUESTIONABLE 186SL079530040YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL079530041---- --- -------------------- --------------- -------------------- 186SL0795300421984 13 none none none 186SL0795300431985 76 178-219,237-252, none 27,55-56,83,254-255 186SL079530044 289-317 186SL0795300451986 90 3-33,214-220 none none 186SL0795300461987 100 none none 49,232-234,261 186SL0795300471988 100 none none 65,150-151,153,181, 186SL079530048 195-196,248,251,266, 186SL079530049 277,280,324 186SL0795300501989 100 none none 57,213,266,349-352 186SL0795300511990 93 181-208 (05)171-(00)172 135 186SL0795300521991 100 none none none 186SL0795300531992 100 none none none 186SL0795300541993 90 11-47 none none 186SL079530055 186SL079530056 QUALITY ASSESSMENT POLICY 186SL079530057 186SL079530058 The quality assessment is mostly based on the residuals 186SL079530059 (observed data minus predicted tides) of the hourly data. This 186SL079530060 assessment also applies to the daily and monthly data since 186SL079530061 they were derived from the quality-controlled hourly data. 186SL079530062 186SL079530063 The following abbreviations are used in the assessment: 186SL079530064 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL079530065 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL079530066 research program; NODC - National Oceanographic Data Center; 186SL079530067 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL079530068 Gaps > 1 mon - missing data in a span greater than one month; 186SL079530069 Refernce - reference. 186SL079530070 186SL079530071 The following corrections are made to the hourly data 186SL079530072 prior to this assessment: 186SL079530073 1) Gaps or obviously wrong data points in a span less than 186SL079530074 25 hours are filled by the predicted tide method*. 186SL079530075 2) Timing errors of exact increments of an hour are corrected 186SL079530076 by shifting the data. 186SL079530077 3) Reference level shifts are only corrected after information 186SL079530078 from tide staff readings or comparative readings with a fixed 186SL079530079 bench mark are checked to verify that the shift was not a 186SL079530080 natural event. If comparative readings are missing or 186SL079530081 incomplete, comparisons of the data with nearby stations 186SL079530082 may warrant the adjustment of some obvious shifts. 186SL079530083 4) Data with unresolved datum shifts are not disseminated. 186SL079530084 However, if sufficient time spans of data are available before 186SL079530085 or after the year(s) with the unresolved shift(s), a subset of 186SL079530086 quality assured data is made available. Thus, the Span field 186SL079530087 in the Quality Assessment may not match the span of the 186SL079530088 distribution data set. As the questionable datum shifts are 186SL079530089 resolved, the data set will be updated. Although this policy 186SL079530090 adds some complexity, it allows more rapid dissemination of 186SL079530091 at least the quality assured years. 186SL079530092 186SL079530093 For each year, the following information is documented from 186SL079530094 the quality-controlled hourly data with dates given as the nth 186SL079530095 day of the year starting from 1 January: 186SL079530096 1) a Completeness Index (CI) based on the percentage of hours 186SL079530097 with available data, 186SL079530098 2) a list of gaps longer than a day, 186SL079530099 3) a summary of days with consecutive missing or obviously 186SL079530100 wrong data in a time span longer than 6 but less than 25 186SL079530101 hours that have been replaced, with hours in parentheses, and 186SL079530102 4) a summary of days with questionable fluctuations in the 186SL079530103 residual series. Fluctuations within the residuals are 186SL079530104 considered significant and are noted if they are greater than 186SL079530105 25 cm. This policy has changed slightly as of October 1992: 186SL079530106 only suspicious fluctuations due to obvious instrumentation 186SL079530107 problems are noted. Minor timing drifts are no longer 186SL079530108 included in the list of questionable days. 186SL079530109 186SL079530110 Note : If the predicted tides poorly model the observed heights 186SL079530111 due to the inability of the tidal analysis to completely resolv 186SL079530112 the non-linear shallow water effects, the residuals are not 186SL079530113 suitable for assessing the data quality. Instead, a subjective 186SL079530114 comment on the quality of the data is provided. 186SL079530115 186SL079530116 *The predicted tides are obtained with the use of a harmonic 186SL079530117 analysis program (Foreman, 1977) which is executed on a year 186SL079530118 of apparently good data for a given station. The Predicted 186SL079530119 Tide Method for filling gaps consists of statistically 186SL079530120 comparing the predicted tides to the observed data and 186SL079530121 shifting the predicted tides in time to correct for timing 186SL079530122 differences. Then the linear interpolation between hourly 186SL079530123 values at the end points of the gap in the residual series is 186SL079530124 added to the corresponding corrected predicted tide data to 186SL079530125 obtain interpolated values over the span of the gap. 186SL079530126 186SL079530127 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL079530128 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL079530129 186SL079530130 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL079530131 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL079530132 Victoria B.C. Pacific Marine Science Report 77-10. 186SL079530133 186SL07956 19841 999999999999999999999999999999999999999999999999 186SL07956 19842 9999999999999999999999999999999999999999 2686000 186SL07956 19851 2550000 2581000 2592000 2643000 2741000 2869040 186SL07956 19852 9999999999999999999999999999999999999999 2642000 186SL07956 19861 99999999 2476030 2525000 2649000 2763000 2714000 186SL07956 19862 275600099999999 2676000 2704000 2733000 2500000 186SL07956 19871 2451000 2478000 2451000 2525000 2667000 2741000 186SL07956 19872 2759000 2667000 2598000 2666000 2841000 2742000 186SL07956 19881 2607000 2601000 2577000 2669000 2800000 2790000 186SL07956 19882 2690000 2688000 2677000 2814000 2844000 2689000 186SL07956 19891 2604000 2548000 2592000 2665000 2806000 2795000 186SL07956 19892 2783000 2720000 2677000 2720000 2761000 2556000 186SL07956 19901 2523000 2469000 2495000 2683000 2747000 2806010 186SL07956 19902 99999999 2774000 2696000 2706000 2741000 2599000 186SL07956 19911 2523000 2537000 2533000 2655000 2691000 2756000 186SL07956 19912 2687000 2658000 2689000 2720000 2705000 2589000 186SL07956 19921 2499000 2464000 2517000 2604000 2756000 2831000 186SL07956 19922 2750000 2766000 2721000 2832000 2718000 2649000 186SL07956 19931 9999999999999999 2539000 2655000 2706000 2756000 186SL07956 19932 2740000 2770000 2690000 2743000 2764000 2723000