186SL0958112110001 638A 19760101 19901231 2001N 11017E 2 00000R 0000 MM 186SL0958212110001 Haikou China PRC Nat. Ocean. Data Center 186SL095830001 186SL095830002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL095830003 by the 186SL095830004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL095830005 JOINT ARCHIVE FOR SEA LEVEL 186SL095830006 186SL095830007Station : Haikou Latitude: 20 01.0N 186SL095830008Country : China Longitude: 110 17.0E 186SL095830009JASL # : 638A Time Meridian: 120E (GMT + 8 hr) 186SL095830010GLOSS # : none TOGA #: none NODC #: 12110001 186SL095830011Contributor : PRC National Oceanographic Data Center 186SL095830012 118, Qiwei Road, Hedong 186SL095830013 District Tianjin, China 186SL095830014Originator : same 186SL095830015Original Data: analog 186SL095830016Instrmnt Type: HCJ-1 Float gauge (1976-1985); 186SL095830017 SCA1-1 Float gauge (1986-1990) 186SL095830018Digitzd Intvl: hourly 186SL095830019Present Data : Hourly, daily, and monthly values obtained by: 186SL095830020 Hourly : digitized as hourly values 186SL095830021 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL095830022 centered on noon applied to the hourly data 186SL095830023 with respective periods of the 95, 50, and 5% 186SL095830024 amplitude points at 124.0, 60.2, and 40.2 hours 186SL095830025 Monthly: Simple average of all daily values; calculated if 186SL095830026 7 or fewer days are missing 186SL095830027Span of data : 01 Jan 1976 - 31 Dec 1990 186SL095830028Gaps > 1 mon : none 186SL095830029Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 186SL095830030Units : millimeters Missing Data Flag :99999 186SL095830031Refernce Levl: The sea level heights are referred to the Tide 186SL095830032 Gauge Zero (TGZ) which is linked to fixed bench 186SL095830033 marks. Bench mark information is 186SL095830034 available upon request from the contributors. 186SL095830035Comment : The residual series are very noisy which are 186SL095830036 probably due to shallow water tides that are not 186SL095830037 resolved by the harmonic analysis. Also the daily 186SL095830038 plot shows noise due to a great amount of energy 186SL095830039 with periods from 1 to 5 days. 186SL095830040 186SL095830041 CI MISSING REPLACED GAPS QUESTIONABLE 186SL095830042YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL095830043---- --- -------------------- --------------- -------------------- 186SL0958300441976 100 none (16)198-(23)198 see comment above 186SL095830045 (15)203-(23)203 186SL095830046 (15)204-(23)204 186SL095830047 (15)292-(23)292 186SL095830048 (15)301-(23)301 186SL095830049 (03)354-(11)354 186SL0958300501977 100 none (15)059-(23)059 see comment above 186SL095830051 (15)061-(23)061 186SL095830052 (15)063-(23)063 186SL095830053 (13)067-(23)067 186SL095830054 (01)305-(11)305 186SL095830055 (15)318-(23)318 186SL095830056 (16)319-(23)319 186SL095830057 (04)363-(11)363 186SL0958300581978 100 none (01)065-(11)065 see comment above 186SL095830059 (04)072-(11)072 186SL095830060 (01)328-(13)328 186SL0958300611979 99 272-273 (01)182-(12)182 see comment above 186SL095830062 (16)274-(23)274 186SL0958300631980 100 none (13)196-(23)196 see comment above 186SL0958300641981 100 none (01)292-(11)292 see comment above 186SL0958300651982 100 none (15)039-(23)039 see comment above 186SL095830066 (13)061-(23)061 186SL095830067 (01)062-(11)062 186SL095830068 (01)063-(11)063 186SL095830069 (01)064-(11)064 186SL095830070 (14)064-(23)064 186SL095830071 (13)131-(23)131 186SL0958300721983 100 none (16)199-(23)199 see comment above 186SL0958300731984 100 none (16)061-(23)061 see comment above 186SL095830074 (16)061-(23)061 186SL0958300751985 100 none none see comment above 186SL0958300761986 100 none none see comment above 186SL0958300771987 100 none (14)332-(23)332 see comment above 186SL0958300781988 100 none none see comment above 186SL0958300791989 100 none (13)157-(23)157 see comment above 186SL0958300801990 99 365 none see comment above 186SL095830081 186SL095830082 QUALITY ASSESSMENT POLICY 186SL095830083 186SL095830084 The quality assessment is mostly based on the residuals 186SL095830085 (observed data minus predicted tides) of the hourly data. This 186SL095830086 assessment also applies to the daily and monthly data since 186SL095830087 they were derived from the quality-controlled hourly data. 186SL095830088 186SL095830089 The following abbreviations are used in the assessment: 186SL095830090 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL095830091 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL095830092 research program; NODC - National Oceanographic Data Center; 186SL095830093 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL095830094 Gaps > 1 mon - missing data in a span greater than one month; 186SL095830095 Refernce - reference. 186SL095830096 186SL095830097 The following corrections are made to the hourly data 186SL095830098 prior to this assessment: 186SL095830099 1) Gaps or obviously wrong data points in a span less than 186SL095830100 25 hours are filled by the predicted tide method*. 186SL095830101 2) Timing errors of exact increments of an hour are corrected 186SL095830102 by shifting the data. 186SL095830103 3) Reference level shifts are only corrected after information 186SL095830104 from tide staff readings or comparative readings with a fixed 186SL095830105 bench mark are checked to verify that the shift was not a 186SL095830106 natural event. If comparative readings are missing or 186SL095830107 incomplete, comparisons of the data with nearby stations 186SL095830108 may warrant the adjustment of some obvious shifts. 186SL095830109 4) Data with unresolved datum shifts are not disseminated. 186SL095830110 However, if sufficient time spans of data are available before 186SL095830111 or after the year(s) with the unresolved shift(s), a subset of 186SL095830112 quality assured data is made available. Thus, the Span field 186SL095830113 in the Quality Assessment may not match the span of the 186SL095830114 distribution data set. As the questionable datum shifts are 186SL095830115 resolved, the data set will be updated. Although this policy 186SL095830116 adds some complexity, it allows more rapid dissemination of 186SL095830117 at least the quality assured years. 186SL095830118 186SL095830119 For each year, the following information is documented from 186SL095830120 the quality-controlled hourly data with dates given as the nth 186SL095830121 day of the year starting from 1 January: 186SL095830122 1) a Completeness Index (CI) based on the percentage of hours 186SL095830123 with available data, 186SL095830124 2) a list of gaps longer than a day, 186SL095830125 3) a summary of days with consecutive missing or obviously 186SL095830126 wrong data in a time span longer than 6 but less than 25 186SL095830127 hours that have been replaced, with hours in parentheses, and 186SL095830128 4) a summary of days with questionable fluctuations in the 186SL095830129 residual series. Fluctuations within the residuals are 186SL095830130 considered significant and are noted if they are greater than 186SL095830131 25 cm. This policy has changed slightly as of October 1992: 186SL095830132 only suspicious fluctuations due to obvious instrumentation 186SL095830133 problems are noted. Minor timing drifts are no longer 186SL095830134 included in the list of questionable days. 186SL095830135 186SL095830136 Note : If the predicted tides poorly model the observed heights 186SL095830137 due to the inability of the tidal analysis to completely resolv 186SL095830138 the non-linear shallow water effects, the residuals are not 186SL095830139 suitable for assessing the data quality. Instead, a subjective 186SL095830140 comment on the quality of the data is provided. 186SL095830141 186SL095830142 *The predicted tides are obtained with the use of a harmonic 186SL095830143 analysis program (Foreman, 1977) which is executed on a year 186SL095830144 of apparently good data for a given station. The Predicted 186SL095830145 Tide Method for filling gaps consists of statistically 186SL095830146 comparing the predicted tides to the observed data and 186SL095830147 shifting the predicted tides in time to correct for timing 186SL095830148 differences. Then the linear interpolation between hourly 186SL095830149 values at the end points of the gap in the residual series is 186SL095830150 added to the corresponding corrected predicted tide data to 186SL095830151 obtain interpolated values over the span of the gap. 186SL095830152 186SL095830153 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL095830154 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL095830155 186SL095830156 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL095830157 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL095830158 Victoria B.C. Pacific Marine Science Report 77-10. 186SL095830159 186SL09586 19761 1479000 1479000 1464000 1487000 1504000 1463000 186SL09586 19762 1518000 1489000 1648000 1646000 1662000 1512000 186SL09586 19771 1468000 1420000 1368000 1404000 1422000 1418000 186SL09586 19772 1499000 1465000 1648000 1645000 1620000 1515000 186SL09586 19781 1432000 1418000 1473000 1438000 1496000 1456000 186SL09586 19782 1455000 1516000 1624000 1782000 1593000 1529000 186SL09586 19791 1401000 1410000 1465000 1451000 1516000 1501000 186SL09586 19792 1495000 1495000 1492020 1735000 1632000 1464000 186SL09586 19801 1417000 1404000 1414000 1444000 1507000 1430000 186SL09586 19802 1455000 1485000 1669000 1691000 1650000 1572000 186SL09586 19811 1519000 1499000 1442000 1488000 1473000 1550000 186SL09586 19812 1504000 1506000 1532000 1712000 1704000 1537000 186SL09586 19821 1450000 1437000 1428000 1469000 1453000 1507000 186SL09586 19822 1483000 1413000 1600000 1613000 1568000 1513000 186SL09586 19831 1438000 1399000 1431000 1419000 1436000 1442000 186SL09586 19832 1460000 1478000 1494000 1676000 1640000 1537000 186SL09586 19841 1449000 1421000 1417000 1469000 1499000 1493000 186SL09586 19842 1427000 1539000 1497000 1710000 1679000 1552000 186SL09586 19851 1412000 1505000 1519000 1460000 1475000 1600000 186SL09586 19852 1499000 1539000 1597000 1667000 1659000 1604000 186SL09586 19861 1448000 1446000 1469000 1445000 1465000 1467000 186SL09586 19862 1495000 1595000 1621000 1661000 1667000 1533000 186SL09586 19871 1503000 1476000 1473000 1484000 1476000 1514000 186SL09586 19872 1474000 1466000 1579000 1643000 1644000 1562000 186SL09586 19881 1512000 1512000 1502000 1504000 1512000 1528000 186SL09586 19882 1489000 1502000 1595000 1821000 1649000 1555000 186SL09586 19891 1574000 1509000 1514000 1485000 1553000 1528000 186SL09586 19892 1576000 1614000 1616000 1762000 1707000 1617000 186SL09586 19901 1607000 1500000 1483000 1552000 1531000 1567000 186SL09586 19902 1549000 1589000 1606000 1725000 1706000 1600010