186SL0773110103101 140A 19831215 19931231 0303N 10122E 2 00000R 0000 MM 186SL0773210103101 Kelang Malaysia Dept. of Survey and Mapping 186SL077330001 186SL077330002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL077330003 by the 186SL077330004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL077330005 JOINT ARCHIVE FOR SEA LEVEL 186SL077330006 186SL077330007Station : Kelang Latitude: 03 03.0N 186SL077330008Country : Malaysia Longitude: 101 21.5E 186SL077330009JASL # : 140A Time Meridian: 120E (GMT + 8 hr) 186SL077330010GLOSS # : none TOGA #: I033 NODC #: 10103101 186SL077330011Contributor : Dept. of Survey and Mapping 186SL077330012 Jalan Gurney 186SL077330013 50578 Kuala Lumpur, Malaysia 186SL077330014Originator : same 186SL077330015Original Data: digital; samples taken every 10 sec; 50 sec average 186SL077330016Instrmnt Type: Magnetic Tape Type Tide Gauge, Model LLT- 186SL077330017 3AD (Kyowa Shoko Co. LTD, Japan) 186SL077330018Digitzd Intvl: one hour 186SL077330019Present Data : Hourly, daily, and monthly values obtained by: 186SL077330020 Hourly : Five-point least squares approximation (more 186SL077330021 information available from the address above) 186SL077330022 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL077330023 centered on noon applied to the hourly data 186SL077330024 with respective periods of the 95, 50, and 5% 186SL077330025 amplitude points at 124.0, 60.2, and 40.2 hours 186SL077330026 Monthly: Simple average of all daily values; calculated if 186SL077330027 7 or fewer days are missing 186SL077330028Span of data : 15 Dec 1983 - 31 Dec 1993 186SL077330029Gaps > 1 mon : none 186SL077330030Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 186SL077330031Units : millimeters Missing Data Flag :99999 186SL077330032Refernce Levl: The sea level heights are referred to the zero 186SL077330033 point assigned to the tide gauge. Bench mark 186SL077330034 information is available upon request from the 186SL077330035 contributors. 186SL077330036Comment : The residual series are very noisy which is 186SL077330037 probably due to shallow water tides that are not 186SL077330038 resolved by the harmonic analysis. The daily and 186SL077330039 monthly means of Kelang and neighboring stations, 186SL077330040 Keling and Lumut, agree very well. Thus, this 186SL077330041 data set is assumed to be of good quality. No 186SL077330042 obvious reference level shifts, timing errors, or 186SL077330043 large gaps are present. 186SL077330044 186SL077330045 CI MISSING REPLACED GAPS QUESTIONABLE 186SL077330046YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL077330047---- --- -------------------- --------------- -------------------- 186SL0773300481983 4 none none see comment above 186SL0773300491984 100 none none " " " 186SL0773300501985 99 240-244 none " " " 186SL0773300511986 100 none none " " " 186SL0773300521987 100 none none " " " 186SL0773300531988 100 none none " " " 186SL0773300541989 97 140-150 none " " " 186SL0773300551990 100 none none " " " 186SL0773300561991 97 318-329 (08)299-(15)299 " " " 186SL077330057 (18)309-(00)310 186SL077330058 (19)310-(01)311 186SL0773300591992 95 288-307 none " " " 186SL0773300601993 100 none none " " " 186SL077330061 186SL077330062 QUALITY ASSESSMENT POLICY 186SL077330063 186SL077330064 The quality assessment is mostly based on the residuals 186SL077330065 (observed data minus predicted tides) of the hourly data. This 186SL077330066 assessment also applies to the daily and monthly data since 186SL077330067 they were derived from the quality-controlled hourly data. 186SL077330068 186SL077330069 The following abbreviations are used in the assessment: 186SL077330070 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL077330071 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL077330072 research program; NODC - National Oceanographic Data Center; 186SL077330073 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL077330074 Gaps > 1 mon - missing data in a span greater than one month; 186SL077330075 Refernce - reference. 186SL077330076 186SL077330077 The following corrections are made to the hourly data 186SL077330078 prior to this assessment: 186SL077330079 1) Gaps or obviously wrong data points in a span less than 186SL077330080 25 hours are filled by the predicted tide method*. 186SL077330081 2) Timing errors of exact increments of an hour are corrected 186SL077330082 by shifting the data. 186SL077330083 3) Reference level shifts are only corrected after information 186SL077330084 from tide staff readings or comparative readings with a fixed 186SL077330085 bench mark are checked to verify that the shift was not a 186SL077330086 natural event. If comparative readings are missing or 186SL077330087 incomplete, comparisons of the data with nearby stations 186SL077330088 may warrant the adjustment of some obvious shifts. 186SL077330089 4) Data with unresolved datum shifts are not disseminated. 186SL077330090 However, if sufficient time spans of data are available before 186SL077330091 or after the year(s) with the unresolved shift(s), a subset of 186SL077330092 quality assured data is made available. Thus, the Span field 186SL077330093 in the Quality Assessment may not match the span of the 186SL077330094 distribution data set. As the questionable datum shifts are 186SL077330095 resolved, the data set will be updated. Although this policy 186SL077330096 adds some complexity, it allows more rapid dissemination of 186SL077330097 at least the quality assured years. 186SL077330098 186SL077330099 For each year, the following information is documented from 186SL077330100 the quality-controlled hourly data with dates given as the nth 186SL077330101 day of the year starting from 1 January: 186SL077330102 1) a Completeness Index (CI) based on the percentage of hours 186SL077330103 with available data, 186SL077330104 2) a list of gaps longer than a day, 186SL077330105 3) a summary of days with consecutive missing or obviously 186SL077330106 wrong data in a time span longer than 6 but less than 25 186SL077330107 hours that have been replaced, with hours in parentheses, and 186SL077330108 4) a summary of days with questionable fluctuations in the 186SL077330109 residual series. Fluctuations within the residuals are 186SL077330110 considered significant and are noted if they are greater than 186SL077330111 25 cm. This policy has changed slightly as of October 1992: 186SL077330112 only suspicious fluctuations due to obvious instrumentation 186SL077330113 problems are noted. Minor timing drifts are no longer 186SL077330114 included in the list of questionable days. 186SL077330115 186SL077330116 Note : If the predicted tides poorly model the observed heights 186SL077330117 due to the inability of the tidal analysis to completely resolv 186SL077330118 the non-linear shallow water effects, the residuals are not 186SL077330119 suitable for assessing the data quality. Instead, a subjective 186SL077330120 comment on the quality of the data is provided. 186SL077330121 186SL077330122 *The predicted tides are obtained with the use of a harmonic 186SL077330123 analysis program (Foreman, 1977) which is executed on a year 186SL077330124 of apparently good data for a given station. The Predicted 186SL077330125 Tide Method for filling gaps consists of statistically 186SL077330126 comparing the predicted tides to the observed data and 186SL077330127 shifting the predicted tides in time to correct for timing 186SL077330128 differences. Then the linear interpolation between hourly 186SL077330129 values at the end points of the gap in the residual series is 186SL077330130 added to the corresponding corrected predicted tide data to 186SL077330131 obtain interpolated values over the span of the gap. 186SL077330132 186SL077330133 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL077330134 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL077330135 186SL077330136 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL077330137 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL077330138 Victoria B.C. Pacific Marine Science Report 77-10. 186SL077330139 186SL07736 19831 999999999999999999999999999999999999999999999999 186SL07736 19832 999999999999999999999999999999999999999999999999 186SL07736 19841 3599000 3558000 3624000 3667000 3736000 3709000 186SL07736 19842 3677000 3713000 3725000 3787000 3642000 3682000 186SL07736 19851 3528000 3560000 3576000 3608000 3672000 3809000 186SL07736 19852 3696000 3618050 3647020 3735000 3734000 3638000 186SL07736 19861 3527000 3470000 3493000 3596000 3661000 3641000 186SL07736 19862 3687000 3710000 3635000 3679000 3722000 3492000 186SL07736 19871 3435000 3457000 3411000 3467000 3592000 3631000 186SL07736 19872 3678000 3589000 3550000 3606000 3805000 3733000 186SL07736 19881 3584000 3560000 3543000 3610000 3729000 3709000 186SL07736 19882 3605000 3620000 3612000 3778000 3817000 3674000 186SL07736 19891 3573000 3520000 3557000 363600099999999 3744000 186SL07736 19892 3700000 3657000 3624000 3686000 3739000 3540000 186SL07736 19901 3502000 3426000 3444000 3619000 3692000 3724000 186SL07736 19902 3614000 3704000 3641000 3661000 3714000 3591000 186SL07736 19911 3505000 3513000 3486000 3609000 3621000 3667000 186SL07736 19912 3591000 3570000 3627000 364400099999999 3589000 186SL07736 19921 3481000 3434000 3476000 3558000 3704000 3736000 186SL07736 19922 3670000 3690000 367400099999999 3692020 3641000 186SL07736 19931 3507000 3458000 3486000 3603000 3643000 3683000 186SL07736 19932 3664000 3692000 3628000 3681000 3729000 3724000