186SL0856110101305 337A 19720101 19811231 0116N 10349E 2 00000R 0000 MM 186SL0856210101305 Victoria Dock Singapore Port of Singapore Authority 186SL085630001 186SL085630002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL085630003 by the 186SL085630004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL085630005 JOINT ARCHIVE FOR SEA LEVEL 186SL085630006 186SL085630007Station : Victoria Dock Latitude: 01 15.8N ? 186SL085630008Country : Singapore Longitude: 103 49.3E ? 186SL085630009JASL # : 337A Time Meridian: 120E (GMT + 8 hr) 186SL085630010GLOSS # : 044 TOGA #: none NODC #: 10101305 186SL085630011Contributor : Port of Singapore Authority 186SL085630012 PSA Building 186SL085630013 460 Alexandra Road 186SL085630014 Singapore 0511 186SL085630015Originator : same 186SL085630016Original Data: analog ? 186SL085630017Instrmnt Type: A.OTT Float Type ? 186SL085630018Digitzd Intvl: 1 hour ? 186SL085630019Present Data : Hourly, daily, and monthly values obtained by: 186SL085630020 Hourly : digitized from chart paper ? 186SL085630021 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL085630022 centered on noon applied to the hourly data 186SL085630023 with respective periods of the 95, 50, and 5% 186SL085630024 amplitude points at 124.0, 60.2, and 40.2 hours 186SL085630025 Monthly: Simple average of all daily values; calculated if 186SL085630026 7 or fewer days are missing 186SL085630027Span of data : 01 Jan 1972 - 31 Dec 1981 186SL085630028Gaps > 1 mon : 27 Mar - 30 Apr 1974 186SL085630029Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 186SL085630030Units : millimeters Missing Data Flag :99999 186SL085630031Refernce Levl: The sea level heights are referred to the chart 186SL085630032 datum which is also the zero level of the tide 186SL085630033 gauge. Bench mark information is available upon 186SL085630034 request from the contributors. 186SL085630035Comment : The residual series are noisy (note questionable 186SL085630036 fluctuations below), which is probably due to 186SL085630037 shallow water tides that are not resolved by the 186SL085630038 harmonic analysis or due to timing drifts of 186SL085630039 less than 15 minutes. The daily and monthly means 186SL085630040 do not reveal any apparent reference level shifts. 186SL085630041 186SL085630042 CI MISSING REPLACED GAPS QUESTIONABLE 186SL085630043YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL085630044---- --- -------------------- --------------- -------------------- 186SL0856300451972 90 82-105,211-218, (02)137-(21)137 19-20,33-36,42-43, 186SL085630046 330-333,354-357, (10)144-(01)145 45-51,61-64,73-80, 186SL085630047 365-366 (02)177-(16)177 105-106,143,171-173, 186SL085630048 (07)363-(21)363 196-198,225-227,253- 186SL085630049 254,279-283,297-300, 186SL085630050 306-308,313,322,326- 186SL085630051 330,334-336 186SL0856300521973 83 1-4,120-130, (13)005-(01)006 9,13,35-42,48-50,69- 186SL085630053 198-201,204-205, (12)015-(00)016 74,78-79,133-134, 186SL085630054 207-216,219-227, (17)240-(08)241 157-163,185-190,241- 186SL085630055 229-235,238-240, (17)242-(02)243 247,313,323-327,349- 186SL085630056 248-254,261-264, (04)355-(23)355 354 186SL085630057 267-269,292-299, (17)365-(23)365 186SL085630058 307-309,344-347 186SL0856300591974 89 44-46,47-49, (17)214-(23)214 6-16,38-44,52-64,66- 186SL085630060 76-77,82-84, (07)337-(15)337 70,85,122-126,130, 186SL085630061 86-120,357-359 145,149-152,175-178, 186SL085630062 204-206,208-210,230- 186SL085630063 234,238-239,252,258- 186SL085630064 262,266-267,286-292, 186SL085630065 312-316,341-344 186SL0856300661975 97 42-44,47-48, (21)032-(06)033 2-7,52,78-79,85-87, 186SL085630067 55-62 (04)037-(12)037 113-114,140-143,167- 186SL085630068 (05)162-(02)163 174,192-203,207-210, 186SL085630069 222-230,249-256,277- 186SL085630070 283,286,306-308,311- 186SL085630071 312,322,329,331-334, 186SL085630072 349-353,361-363 186SL0856300731976 98 46-48,285-287, (14)003-(13)004 5,11,23-24,32-33,39- 186SL085630074 297-302 (10)270-(02)271 40,48-49,62-69,75- 186SL085630075 79,104-107,118-119, 186SL085630076 131-133,158-161,181, 186SL085630077 187-190,210,213-216, 186SL085630078 229,240-242,267-269, 186SL085630079 272-274,287-288,296- 186SL085630080 297,322-325,351-352, 186SL085630081 361 186SL0856300821977 99 52-53,214-217 (10)019-(02)020 13-16,41-42,48-51, 186SL085630083 (04)132-(16)132 53,65,113,119,158, 186SL085630084 (16)132-(04)133 177-179,229-232, 186SL085630085 257-262,285-286,310- 186SL085630086 313,339-341 186SL0856300871978 99 37-40,82-84 (02)328-(00)329 4-5,116-117,204-205, 186SL085630088 277,299,307-309,358, 186SL085630089 359 186SL0856300901979 98 73-82 (17)151-(23)151 33-37,61-62,168-169, 186SL085630091 272 186SL0856300921980 100 none (16)237-(15)238 47-48,186,220,340 186SL0856300931981 99 365 none 2,10-14,39-42,69, 186SL085630094 110-111,124,135,204, 186SL085630095 246,273-274,282,295- 186SL085630096 297,317-318,340-341, 186SL085630097 353-356 186SL085630098 186SL085630099 QUALITY ASSESSMENT POLICY 186SL085630100 186SL085630101 The quality assessment is mostly based on the residuals 186SL085630102 (observed data minus predicted tides) of the hourly data. This 186SL085630103 assessment also applies to the daily and monthly data since 186SL085630104 they were derived from the quality-controlled hourly data. 186SL085630105 186SL085630106 The following abbreviations are used in the assessment: 186SL085630107 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL085630108 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL085630109 research program; NODC - National Oceanographic Data Center; 186SL085630110 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL085630111 Gaps > 1 mon - missing data in a span greater than one month; 186SL085630112 Refernce - reference. 186SL085630113 186SL085630114 The following corrections are made to the hourly data 186SL085630115 prior to this assessment: 186SL085630116 1) Gaps or obviously wrong data points in a span less than 186SL085630117 25 hours are filled by the predicted tide method*. 186SL085630118 2) Timing errors of exact increments of an hour are corrected 186SL085630119 by shifting the data. 186SL085630120 3) Reference level shifts are only corrected after information 186SL085630121 from tide staff readings or comparative readings with a fixed 186SL085630122 bench mark are checked to verify that the shift was not a 186SL085630123 natural event. If comparative readings are missing or 186SL085630124 incomplete, comparisons of the data with nearby stations 186SL085630125 may warrant the adjustment of some obvious shifts. 186SL085630126 4) Data with unresolved datum shifts are not disseminated. 186SL085630127 However, if sufficient time spans of data are available before 186SL085630128 or after the year(s) with the unresolved shift(s), a subset of 186SL085630129 quality assured data is made available. Thus, the Span field 186SL085630130 in the Quality Assessment may not match the span of the 186SL085630131 distribution data set. As the questionable datum shifts are 186SL085630132 resolved, the data set will be updated. Although this policy 186SL085630133 adds some complexity, it allows more rapid dissemination of 186SL085630134 at least the quality assured years. 186SL085630135 186SL085630136 For each year, the following information is documented from 186SL085630137 the quality-controlled hourly data with dates given as the nth 186SL085630138 day of the year starting from 1 January: 186SL085630139 1) a Completeness Index (CI) based on the percentage of hours 186SL085630140 with available data, 186SL085630141 2) a list of gaps longer than a day, 186SL085630142 3) a summary of days with consecutive missing or obviously 186SL085630143 wrong data in a time span longer than 6 but less than 25 186SL085630144 hours that have been replaced, with hours in parentheses, and 186SL085630145 4) a summary of days with questionable fluctuations in the 186SL085630146 residual series. Fluctuations within the residuals are 186SL085630147 considered significant and are noted if they are greater than 186SL085630148 25 cm. This policy has changed slightly as of October 1992: 186SL085630149 only suspicious fluctuations due to obvious instrumentation 186SL085630150 problems are noted. Minor timing drifts are no longer 186SL085630151 included in the list of questionable days. 186SL085630152 186SL085630153 Note : If the predicted tides poorly model the observed heights 186SL085630154 due to the inability of the tidal analysis to completely resolv 186SL085630155 the non-linear shallow water effects, the residuals are not 186SL085630156 suitable for assessing the data quality. Instead, a subjective 186SL085630157 comment on the quality of the data is provided. 186SL085630158 186SL085630159 *The predicted tides are obtained with the use of a harmonic 186SL085630160 analysis program (Foreman, 1977) which is executed on a year 186SL085630161 of apparently good data for a given station. The Predicted 186SL085630162 Tide Method for filling gaps consists of statistically 186SL085630163 comparing the predicted tides to the observed data and 186SL085630164 shifting the predicted tides in time to correct for timing 186SL085630165 differences. Then the linear interpolation between hourly 186SL085630166 values at the end points of the gap in the residual series is 186SL085630167 added to the corresponding corrected predicted tide data to 186SL085630168 obtain interpolated values over the span of the gap. 186SL085630169 186SL085630170 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL085630171 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL085630172 186SL085630173 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL085630174 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL085630175 Victoria B.C. Pacific Marine Science Report 77-10. 186SL085630176 186SL08566 19721 1713000 15830009999999999999999 1442000 1432000 186SL08566 19722 1390030 1487050 1534000 1568000 1588040 1655060 186SL08566 19731 1629040 1583000 1602000 152701099999999 1482000 186SL08566 19732 99999999999999999999999999999999 1758030 1851040 186SL08566 19741 1686000 16930609999999999999999 1509000 1452000 186SL08566 19742 1445000 1445000 1527000 1584000 1694000 1684030 186SL08566 19751 165700099999999 1540030 1529000 1492000 1439000 186SL08566 19752 1434000 1445000 1540000 1602000 1712000 1855000 186SL08566 19761 1700000 1586030 1546000 1485000 1492000 1449000 186SL08566 19762 1493000 1490000 149800099999999 1733000 1742000 186SL08566 19771 1658000 1714020 1617000 1500000 1443000 1410000 186SL08566 19772 1433000 1451040 1531000 1609000 1711000 1718000 186SL08566 19781 1654000 1631040 1541030 1497000 1536000 1481000 186SL08566 19782 1458000 1451000 1479000 1640000 1660000 1716000 186SL08566 19791 1592000 156400099999999 1518000 1505000 1465000 186SL08566 19792 1425000 1448000 1523000 1682000 1717000 1714000 186SL08566 19801 1623000 1619000 1502000 1487000 1486000 1480000 186SL08566 19802 1444000 1434000 1487000 1564000 1672000 1716000 186SL08566 19811 1684000 1587000 1544000 1507000 1510000 1482000 186SL08566 19812 1484000 1468000 1522000 1529000 1693000 1799010