186SL0957111109801 637A 19750101 19901231 1906N 10837E 2 00000R 0000 MM 186SL0957211109801 Dongfang China PRC Nat. Ocean. Data Center 186SL095730001 186SL095730002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL095730003 by the 186SL095730004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL095730005 JOINT ARCHIVE FOR SEA LEVEL 186SL095730006 186SL095730007Station : Dongfang Latitude: 19 06.0N 186SL095730008Country : China Longitude: 108 37.0E 186SL095730009JASL # : 637A Time Meridian: 120E (GMT + 8 hr) 186SL095730010GLOSS # : none TOGA #: none NODC #: 11109801 186SL095730011Contributor : PRC National Oceanographic Data Center 186SL095730012 118, Qiwei Road, Hedong 186SL095730013 District Tianjin, China 186SL095730014Originator : same 186SL095730015Original Data: analog 186SL095730016Instrmnt Type: HCJ-1 Float gauge (1975-1985); 186SL095730017 SCA1-1 Float gauge (1986-90) 186SL095730018Digitzd Intvl: hourly 186SL095730019Present Data : Hourly, daily, and monthly values obtained by: 186SL095730020 Hourly : digitized as hourly values 186SL095730021 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL095730022 centered on noon applied to the hourly data 186SL095730023 with respective periods of the 95, 50, and 5% 186SL095730024 amplitude points at 124.0, 60.2, and 40.2 hours 186SL095730025 Monthly: Simple average of all daily values; calculated if 186SL095730026 7 or fewer days are missing 186SL095730027Span of data : 01 Jan 1975 - 31 Dec 1990 186SL095730028Gaps > 1 mon : none 186SL095730029Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 186SL095730030Units : millimeters Missing Data Flag :99999 186SL095730031Refernce Levl: The sea level heights are referred to the Tide 186SL095730032 Gauge Zero (TGZ) which is linked to fixed bench 186SL095730033 marks. The TGZ is relative to the 1975 level. 186SL095730034 Original data for 1982-1990 was lowered 240 mm 186SL095730035 to adjust to the 1975 level. Bench mark 186SL095730036 information is available upon request from 186SL095730037 the contributors. 186SL095730038Comment : The daily and monthly values indicate that the 186SL095730039 data set is of good quality. The timing of the 186SL095730040 hourly values is also good. 186SL095730041 186SL095730042 CI MISSING REPLACED GAPS QUESTIONABLE 186SL095730043YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL095730044---- --- -------------------- --------------- -------------------- 186SL0957300451975 100 none none none 186SL0957300461976 100 none none none 186SL0957300471977 100 none none none 186SL0957300481978 100 none (16)029-(23)029 none 186SL0957300491979 100 none none none 186SL0957300501990 100 none none none 186SL0957300511981 100 none (16)365-(23)365 none 186SL0957300521982 100 none (13)345-(23)345 none 186SL0957300531983 100 none (15)124-(23)124 none 186SL0957300541984 100 none none none 186SL0957300551985 100 none none none 186SL0957300561986 100 none (15)305-(23)305 none 186SL0957300571987 100 none none none 186SL0957300581988 100 none none none 186SL095730059 (16)308-(23)308 none 186SL0957300601989 100 none none none 186SL0957300611990 100 none none none 186SL095730062 186SL095730063 QUALITY ASSESSMENT POLICY 186SL095730064 186SL095730065 The quality assessment is mostly based on the residuals 186SL095730066 (observed data minus predicted tides) of the hourly data. This 186SL095730067 assessment also applies to the daily and monthly data since 186SL095730068 they were derived from the quality-controlled hourly data. 186SL095730069 186SL095730070 The following abbreviations are used in the assessment: 186SL095730071 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL095730072 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL095730073 research program; NODC - National Oceanographic Data Center; 186SL095730074 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL095730075 Gaps > 1 mon - missing data in a span greater than one month; 186SL095730076 Refernce - reference. 186SL095730077 186SL095730078 The following corrections are made to the hourly data 186SL095730079 prior to this assessment: 186SL095730080 1) Gaps or obviously wrong data points in a span less than 186SL095730081 25 hours are filled by the predicted tide method*. 186SL095730082 2) Timing errors of exact increments of an hour are corrected 186SL095730083 by shifting the data. 186SL095730084 3) Reference level shifts are only corrected after information 186SL095730085 from tide staff readings or comparative readings with a fixed 186SL095730086 bench mark are checked to verify that the shift was not a 186SL095730087 natural event. If comparative readings are missing or 186SL095730088 incomplete, comparisons of the data with nearby stations 186SL095730089 may warrant the adjustment of some obvious shifts. 186SL095730090 4) Data with unresolved datum shifts are not disseminated. 186SL095730091 However, if sufficient time spans of data are available before 186SL095730092 or after the year(s) with the unresolved shift(s), a subset of 186SL095730093 quality assured data is made available. Thus, the Span field 186SL095730094 in the Quality Assessment may not match the span of the 186SL095730095 distribution data set. As the questionable datum shifts are 186SL095730096 resolved, the data set will be updated. Although this policy 186SL095730097 adds some complexity, it allows more rapid dissemination of 186SL095730098 at least the quality assured years. 186SL095730099 186SL095730100 For each year, the following information is documented from 186SL095730101 the quality-controlled hourly data with dates given as the nth 186SL095730102 day of the year starting from 1 January: 186SL095730103 1) a Completeness Index (CI) based on the percentage of hours 186SL095730104 with available data, 186SL095730105 2) a list of gaps longer than a day, 186SL095730106 3) a summary of days with consecutive missing or obviously 186SL095730107 wrong data in a time span longer than 6 but less than 25 186SL095730108 hours that have been replaced, with hours in parentheses, and 186SL095730109 4) a summary of days with questionable fluctuations in the 186SL095730110 residual series. Fluctuations within the residuals are 186SL095730111 considered significant and are noted if they are greater than 186SL095730112 25 cm. This policy has changed slightly as of October 1992: 186SL095730113 only suspicious fluctuations due to obvious instrumentation 186SL095730114 problems are noted. Minor timing drifts are no longer 186SL095730115 included in the list of questionable days. 186SL095730116 186SL095730117 Note : If the predicted tides poorly model the observed heights 186SL095730118 due to the inability of the tidal analysis to completely resolv 186SL095730119 the non-linear shallow water effects, the residuals are not 186SL095730120 suitable for assessing the data quality. Instead, a subjective 186SL095730121 comment on the quality of the data is provided. 186SL095730122 186SL095730123 *The predicted tides are obtained with the use of a harmonic 186SL095730124 analysis program (Foreman, 1977) which is executed on a year 186SL095730125 of apparently good data for a given station. The Predicted 186SL095730126 Tide Method for filling gaps consists of statistically 186SL095730127 comparing the predicted tides to the observed data and 186SL095730128 shifting the predicted tides in time to correct for timing 186SL095730129 differences. Then the linear interpolation between hourly 186SL095730130 values at the end points of the gap in the residual series is 186SL095730131 added to the corresponding corrected predicted tide data to 186SL095730132 obtain interpolated values over the span of the gap. 186SL095730133 186SL095730134 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL095730135 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL095730136 186SL095730137 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL095730138 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL095730139 Victoria B.C. Pacific Marine Science Report 77-10. 186SL095730140 186SL09576 19751 1676000 1659000 1692000 1647000 1606000 1561000 186SL09576 19752 1528000 1585000 1703000 1803000 1817000 1738000 186SL09576 19761 1671000 1673000 1624000 1661000 1647000 1595000 186SL09576 19762 1635000 1604000 1739000 1802000 1823000 1683000 186SL09576 19771 1641000 1592000 1534000 1570000 1560000 1551000 186SL09576 19772 1621000 1587000 1789000 1812000 1796000 1690000 186SL09576 19781 1612000 1588000 1643000 1618000 1648000 1601000 186SL09576 19782 1593000 1644000 1783000 1907000 1775000 1715000 186SL09576 19791 1602000 1603000 1660000 1646000 1670000 1653000 186SL09576 19792 1631000 1612000 1651000 1877000 1794000 1650000 186SL09576 19801 1606000 1608000 1605000 1616000 1660000 1600000 186SL09576 19802 1571000 1622000 1820000 1854000 1828000 1775000 186SL09576 19811 1727000 1691000 1628000 1658000 1626000 1662000 186SL09576 19812 1635000 1628000 1694000 1868000 1876000 1715000 186SL09576 19821 1642000 1612000 1608000 1649000 1621000 1636000 186SL09576 19822 1609000 1541000 1733000 1773000 1738000 1657000 186SL09576 19831 1599000 1551000 1571000 1574000 1579000 1581000 186SL09576 19832 1598000 1622000 1630000 1833000 1814000 1722000 186SL09576 19841 1616000 1583000 1566000 1637000 1653000 1618000 186SL09576 19842 1544000 1642000 1627000 1839000 1822000 1700000 186SL09576 19851 1571000 1648000 1657000 1586000 1587000 1647000 186SL09576 19852 1577000 1602000 1669000 1795000 1799000 1746000 186SL09576 19861 1630000 1606000 1629000 1598000 1577000 1580000 186SL09576 19862 1578000 1688000 1720000 1808000 1803000 1678000 186SL09576 19871 1632000 1597000 1585000 1618000 1588000 1587000 186SL09576 19872 1545000 1580000 1675000 1738000 1758000 1680000 186SL09576 19881 1638000 1638000 1612000 1626000 1603000 1608000 186SL09576 19882 1570000 1574000 1669000 1890000 1746000 1658000 186SL09576 19891 1670000 1607000 1619000 1594000 1637000 1611000 186SL09576 19892 1636000 1681000 1692000 1857000 1806000 1729000 186SL09576 19901 1728000 1612000 1590000 1641000 1613000 1617000 186SL09576 19902 1602000 1636000 1685000 1831000 1787000 1697010