186SL0756171159501 060A 19730101 19931231 1944N 15504W 2 00000R 0000 MM 186SL0756271159501 Hilo USA National Ocean Service 186SL075630001 186SL075630002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL075630003 by the 186SL075630004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL075630005 JOINT ARCHIVE FOR SEA LEVEL 186SL075630006 186SL075630007Station : Hilo, Hawaii Latitude: 19 44.0N 186SL075630008Country : USA Longitude: 155 04.0W 186SL075630009JASL # : 060A Time Meridian: 150W (GMT - 10 hr) 186SL075630010GLOSS # : 287 TOGA #: P056 NODC #: 71159501 186SL075630011Contributor : National Ocean Service (NOS) 186SL075630012 National Ocean. and Atmos. Administration (NOAA) 186SL075630013 N/OES22 186SL075630014 SSMC4, STATION 7109 186SL075630015 1305 East West Highway 186SL075630016 Silver Spring, MD. 20910-3233 186SL075630017Originator : same 186SL075630018Original Data: analog (standard); digital (ADR and NGWLMS) 186SL075630019Instrmnt Type: standard mechanical (1973-1974); analog-to-digital 186SL075630020 (ADR) recorder (1975-1990); Aquatrak acoustic 186SL075630021 gauge, NOAA Next Generation Water Level Measuring 186SL075630022 System (NGWLMS) (1991-) 186SL075630023Digitzd Intvl: hourly (standard); six-minute (adr and NGWLMS) 186SL075630024Present Data : Hourly, daily, and monthly values obtained by: 186SL075630025 Hourly : The original digitizing interval was hourly 186SL075630026 (standard); spot sampling on the hour (adr/NGWLMS) 186SL075630027 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL075630028 centered on noon applied to the hourly data 186SL075630029 with respective periods of the 95, 50, and 5% 186SL075630030 amplitude points at 124.0, 60.2, and 40.2 hours 186SL075630031 Monthly: Simple average of all daily values; calculated if 186SL075630032 7 or fewer days are missing 186SL075630033Span of data : 01 Jan 1973 - 31 Dec 1993 186SL075630034Gaps > 1 mon : none 186SL075630035Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 186SL075630036Units : millimeters Missing Data Flag :99999 186SL075630037Refernce Levl: All heights have been referred to the station tide 186SL075630038 staff zero which is linked to fixed bench marks 186SL075630039Comment : The hourly residuals reveal a possible reference 186SL075630040 level shift on 12 Sep, 1974 (-8 cm); however the 186SL075630041 shift is not evident in the daily means or with 186SL075630042 differences with daily means of Kahului. 186SL075630043 Otherwise, the daily and monthly means reveal 186SL075630044 no apparent reference level changes or trends. 186SL075630045 186SL075630046 CI MISSING REPLACED GAPS QUESTIONABLE 186SL075630047YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL075630048---- --- -------------------- --------------- -------------------- 186SL0756300491973 99 1 none 68-71,214-216,241- 186SL075630050 242,232-233,302-303 186SL0756300511974 100 none none 6-7,42-43,66-67 186SL0756300521975 91 1-32 none 84 186SL0756300531976 94 189-198,207-211, (00)021-(15)021 184-185 186SL075630054 247-251,312-314 (02)324-(15)324 186SL075630055 (01)325-(23)325 186SL0756300561977 99 73-77 (10)274-(18)274 none 186SL0756300571978 98 200-205 none none 186SL0756300581979 100 none none none 186SL0756300591980 100 none none none 186SL0756300601981 98 335-341 none none 186SL0756300611982 100 none none none 186SL0756300621983 100 none none none 186SL0756300631984 100 none none 296 186SL0756300641985 100 none none none 186SL0756300651986 100 none none none 186SL0756300661987 100 none none none 186SL0756300671988 100 none none none 186SL0756300681989 100 none none none 186SL0756300691990 100 none none none 186SL0756300701991 100 none none none 186SL0756300711992 100 none (22)046-(23)047 none 186SL075630072 (15)062-(18)063 186SL0756300731993 100 none none none 186SL075630074 186SL075630075 QUALITY ASSESSMENT POLICY 186SL075630076 186SL075630077 The quality assessment is mostly based on the residuals 186SL075630078 (observed data minus predicted tides) of the hourly data. This 186SL075630079 assessment also applies to the daily and monthly data since 186SL075630080 they were derived from the quality-controlled hourly data. 186SL075630081 186SL075630082 The following abbreviations are used in the assessment: 186SL075630083 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL075630084 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL075630085 research program; NODC - National Oceanographic Data Center; 186SL075630086 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL075630087 Gaps > 1 mon - missing data in a span greater than one month; 186SL075630088 Refernce - reference. 186SL075630089 186SL075630090 The following corrections are made to the hourly data 186SL075630091 prior to this assessment: 186SL075630092 1) Gaps or obviously wrong data points in a span less than 186SL075630093 25 hours are filled by the predicted tide method*. 186SL075630094 2) Timing errors of exact increments of an hour are corrected 186SL075630095 by shifting the data. 186SL075630096 3) Reference level shifts are only corrected after information 186SL075630097 from tide staff readings or comparative readings with a fixed 186SL075630098 bench mark are checked to verify that the shift was not a 186SL075630099 natural event. If comparative readings are missing or 186SL075630100 incomplete, comparisons of the data with nearby stations 186SL075630101 may warrant the adjustment of some obvious shifts. 186SL075630102 4) Data with unresolved datum shifts are not disseminated. 186SL075630103 However, if sufficient time spans of data are available before 186SL075630104 or after the year(s) with the unresolved shift(s), a subset of 186SL075630105 quality assured data is made available. Thus, the Span field 186SL075630106 in the Quality Assessment may not match the span of the 186SL075630107 distribution data set. As the questionable datum shifts are 186SL075630108 resolved, the data set will be updated. Although this policy 186SL075630109 adds some complexity, it allows more rapid dissemination of 186SL075630110 at least the quality assured years. 186SL075630111 186SL075630112 For each year, the following information is documented from 186SL075630113 the quality-controlled hourly data with dates given as the nth 186SL075630114 day of the year starting from 1 January: 186SL075630115 1) a Completeness Index (CI) based on the percentage of hours 186SL075630116 with available data, 186SL075630117 2) a list of gaps longer than a day, 186SL075630118 3) a summary of days with consecutive missing or obviously 186SL075630119 wrong data in a time span longer than 6 but less than 25 186SL075630120 hours that have been replaced, with hours in parentheses, and 186SL075630121 4) a summary of days with questionable fluctuations in the 186SL075630122 residual series. Fluctuations within the residuals are 186SL075630123 considered significant and are noted if they are greater than 186SL075630124 25 cm. This policy has changed slightly as of October 1992: 186SL075630125 only suspicious fluctuations due to obvious instrumentation 186SL075630126 problems are noted. Minor timing drifts are no longer 186SL075630127 included in the list of questionable days. 186SL075630128 186SL075630129 Note : If the predicted tides poorly model the observed heights 186SL075630130 due to the inability of the tidal analysis to completely resolv 186SL075630131 the non-linear shallow water effects, the residuals are not 186SL075630132 suitable for assessing the data quality. Instead, a subjective 186SL075630133 comment on the quality of the data is provided. 186SL075630134 186SL075630135 *The predicted tides are obtained with the use of a harmonic 186SL075630136 analysis program (Foreman, 1977) which is executed on a year 186SL075630137 of apparently good data for a given station. The Predicted 186SL075630138 Tide Method for filling gaps consists of statistically 186SL075630139 comparing the predicted tides to the observed data and 186SL075630140 shifting the predicted tides in time to correct for timing 186SL075630141 differences. Then the linear interpolation between hourly 186SL075630142 values at the end points of the gap in the residual series is 186SL075630143 added to the corresponding corrected predicted tide data to 186SL075630144 obtain interpolated values over the span of the gap. 186SL075630145 186SL075630146 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL075630147 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL075630148 186SL075630149 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL075630150 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL075630151 Victoria B.C. Pacific Marine Science Report 77-10. 186SL075630152 186SL07566 19731 1397010 1376000 1444000 1381000 1320000 1394000 186SL07566 19732 1445000 1530000 1502000 1546000 1494000 1522000 186SL07566 19741 1533000 1455000 1514000 1522000 1517000 1490000 186SL07566 19742 1596000 1647000 1611000 1619000 1613000 1476000 186SL07566 19751 99999999 1482010 1418000 1410000 1472000 1339000 186SL07566 19752 1389000 1535000 1464000 1482000 1419000 1382000 186SL07566 19761 1399000 1398000 1432000 1428000 1451000 1397000 186SL07566 19762 99999999 1529000 1555050 1508000 1543030 1504000 186SL07566 19771 1446000 1439000 1419060 1418000 1369000 1438000 186SL07566 19772 1508000 1523000 1549000 1567000 1540000 1541000 186SL07566 19781 1524000 1505000 1517000 1581000 1507000 1555000 186SL07566 19782 1595070 1618000 1626000 1683000 1597000 1516000 186SL07566 19791 1534000 1465000 1500000 1578000 1544000 1504000 186SL07566 19792 1513000 1534000 1513000 1596000 1542000 1555000 186SL07566 19801 1597000 1564000 1610000 1567000 1528000 1424000 186SL07566 19802 1558000 1640000 1609000 1602000 1569000 1549000 186SL07566 19811 1589000 1554000 1513000 1553000 1563000 1567000 186SL07566 19812 1554000 1626000 1656000 1611000 1569000 1564070 186SL07566 19821 1557000 1479000 1444000 1497000 1420000 1417000 186SL07566 19822 1490000 1579000 1591000 1674000 1576000 1592000 186SL07566 19831 1607000 1569000 1543000 1512000 1496000 1491000 186SL07566 19832 1535000 1570000 1632000 1550000 1498000 1539000 186SL07566 19841 1522000 1481000 1539000 1500000 1511000 1571000 186SL07566 19842 1558000 1659000 1671000 1657000 1581000 1582000 186SL07566 19851 1572000 1539000 1527000 1449000 1462000 1511000 186SL07566 19852 1522000 1553000 1574000 1571000 1546000 1468000 186SL07566 19861 1464000 1486000 1417000 1394000 1476000 1444000 186SL07566 19862 1431000 1546000 1568000 1559000 1553000 1539000 186SL07566 19871 1582000 1542000 1518000 1494000 1516000 1514000 186SL07566 19872 1515000 1565000 1568000 1547000 1667000 1577000 186SL07566 19881 1544000 1618000 1589000 1512000 1519000 1505000 186SL07566 19882 1558000 1614000 1601000 1620000 1605000 1560000 186SL07566 19891 1510000 1534000 1566000 1542000 1483000 1538000 186SL07566 19892 1505000 1581000 1571000 1562000 1556000 1483000 186SL07566 19901 1478000 1489000 1474000 1494000 1438000 1436000 186SL07566 19902 1469000 1513000 1552000 1574000 1509000 1542000 186SL07566 19911 1548000 1523000 1472000 1443000 1486000 1486000 186SL07566 19912 1526000 1589000 1522000 1539000 1617000 1586000 186SL07566 19921 1629000 1602000 1574000 1567000 1571000 1554000 186SL07566 19922 1556000 1515000 1576000 1632000 1637000 1603000 186SL07566 19931 1571000 1554000 1568000 1622000 1589000 1599000 186SL07566 19932 1627000 1583000 1639000 1612000 1540000 1562000