186SL0700111169601 051A 19730101 19921231 1917N 16637E 2 00000R 0000 MM 186SL0700211169601 Wake USA Trust National Ocean Service 186SL070030001 186SL070030002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL070030003 by the 186SL070030004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL070030005 JOINT ARCHIVE FOR SEA LEVEL 186SL070030006 186SL070030007Station : Wake Latitude: 19 17.0N 186SL070030008Country : USA Trust Longitude: 166 37.0E 186SL070030009JASL # : 051A Time Meridian: 180E (GMT + 12 hr) 186SL070030010GLOSS # : 105 TOGA #: P040 NODC #: 11169601 186SL070030011Contributor : National Ocean Service (NOS) 186SL070030012 National Ocean. and Atmos. Administration (NOAA) 186SL070030013 N/OES22 186SL070030014 SSMC4, STATION 7109 186SL070030015 1305 East West Highway 186SL070030016 Silver Spring, MD. 20910-3233 186SL070030017Originator : same 186SL070030018Original Data: analog (standard); digital (ADR and NGWLMS) 186SL070030019Instrmnt Type: standard mechanical (1973-1974); analog-to-digital 186SL070030020 (ADR) recorder (1975-1990); Aquatrak acoustic 186SL070030021 gauge, NOAA Next Generation Water Level Measuring 186SL070030022 System (NGWLMS) (1991-) 186SL070030023Digitzd Intvl: hourly (standard); six-minute (adr and NGWLMS) 186SL070030024Present Data : Hourly, daily, and monthly values obtained by: 186SL070030025 Hourly : The original digitizing interval was hourly 186SL070030026 (standard); spot sampling on the hour (adr/NGWLMS) 186SL070030027 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL070030028 centered on noon applied to the hourly data 186SL070030029 with respective periods of the 95, 50, and 5% 186SL070030030 amplitude points at 124.0, 60.2, and 40.2 hours 186SL070030031 Monthly: Simple average of all daily values; calculated if 186SL070030032 7 or fewer days are missing 186SL070030033Span of data : 01 Jan 1973 - 31 Dec 1992 186SL070030034Gaps > 1 mon : 1 - 31 Jan 1975; 12 Jan - 1 Mar 1978; 186SL070030035 31 Dec 1978 - 24 Feb 1979; 1 Mar 1981 - 21 Aug 1982 186SL070030036Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 186SL070030037Units : millimeters Missing Data Flag :99999 186SL070030038Refernce Levl: All heights have been referred to the station tide 186SL070030039 staff zero which is linked to fixed bench marks 186SL070030040Comment : The daily and monthly means reveal no apparent 186SL070030041 reference level changes or trends. 186SL070030042 186SL070030043 CI MISSING REPLACED GAPS QUESTIONABLE 186SL070030044YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL070030045---- --- -------------------- --------------- -------------------- 186SL0700300461973 92 222-244,245-249 (05)217-(03)218 38-39 186SL070030047 (15)251-(02)252 186SL070030048 (17)253-(01)254 186SL0700300491974 81 see @ below see # below 225-227,258,261-262, 186SL070030050 276-278,288-294, 186SL070030051 302-304 186SL0700300521975 91 1-31,274-276 (03)032-(00)033 321 186SL070030053 (04)099-(01)100 186SL070030054 (20)105-(01)106 186SL070030055 (09)278-(02)279 186SL0700300561976 100 none none 63,73-75 186SL0700300571977 97 255-259,266-269 none none 186SL070030058 332-334 186SL0700300591978 86 11-60,365 none none 186SL0700300601979 85 1-54 none none 186SL0700300611980 100 none none 274-275,360-361 186SL0700300621981 16 60-365 none none 186SL0700300631982 36 1-233 none none 186SL0700300641983 100 none none none 186SL0700300651984 100 none none 75-77 186SL0700300661985 100 none none none 186SL0700300671986 100 none none 227-236,318 186SL0700300681987 100 none none 253-257 186SL0700300691988 100 none none none 186SL0700300701989 100 none none none 186SL0700300711990 100 none none none 186SL0700300721991 100 none (00)152-(22)152 none 186SL0700300731992 100 none none none 186SL070030074 @ : 15-17,26-27,51-55,65-66,77-79,92-93,107-110,139-143, 186SL070030075 145-147,160-169,179-184,187-189,229-234,271-274,282- 186SL070030076 283,304-310,317-318 186SL070030077 # : (20)084-(03)085,(13)087-(03)088,(17)089-(02)090, 186SL070030078 (12)091-(21)091,(14)096-(03)097,(03)098-(21)098, 186SL070030079 (14)099-(01)100,(12)100-(01)101,(12)102-(01)103, 186SL070030080 (12)104-(02)105,(05)113-(02)114,(16)116-(03)117, 186SL070030081 (07)117-(03)118,(15)127-(03)128,(17)134-(03)135, 186SL070030082 (08)149-(21)149,(16)177-(03)178,(07)190-(04)191, 186SL070030083 (08)218-(04)219,(19)239-(04)240,(12)243-(19)243, 186SL070030084 (14)262-(01)263,(17)274-(04)275,(20)278-(04)279, 186SL070030085 (18)322-(00)323 186SL070030086 186SL070030087 QUALITY ASSESSMENT POLICY 186SL070030088 186SL070030089 The quality assessment is mostly based on the residuals 186SL070030090 (observed data minus predicted tides) of the hourly data. This 186SL070030091 assessment also applies to the daily and monthly data since 186SL070030092 they were derived from the quality-controlled hourly data. 186SL070030093 186SL070030094 The following abbreviations are used in the assessment: 186SL070030095 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL070030096 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL070030097 research program; NODC - National Oceanographic Data Center; 186SL070030098 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL070030099 Gaps > 1 mon - missing data in a span greater than one month; 186SL070030100 Refernce - reference. 186SL070030101 186SL070030102 The following corrections are made to the hourly data 186SL070030103 prior to this assessment: 186SL070030104 1) Gaps or obviously wrong data points in a span less than 186SL070030105 25 hours are filled by the predicted tide method*. 186SL070030106 2) Timing errors of exact increments of an hour are corrected 186SL070030107 by shifting the data. 186SL070030108 3) Reference level shifts are only corrected after information 186SL070030109 from tide staff readings or comparative readings with a fixed 186SL070030110 bench mark are checked to verify that the shift was not a 186SL070030111 natural event. If comparative readings are missing or 186SL070030112 incomplete, comparisons of the data with nearby stations 186SL070030113 may warrant the adjustment of some obvious shifts. 186SL070030114 4) Data with unresolved datum shifts are not disseminated. 186SL070030115 However, if sufficient time spans of data are available before 186SL070030116 or after the year(s) with the unresolved shift(s), a subset of 186SL070030117 quality assured data is made available. Thus, the Span field 186SL070030118 in the Quality Assessment may not match the span of the 186SL070030119 distribution data set. As the questionable datum shifts are 186SL070030120 resolved, the data set will be updated. Although this policy 186SL070030121 adds some complexity, it allows more rapid dissemination of 186SL070030122 at least the quality assured years. 186SL070030123 186SL070030124 For each year, the following information is documented from 186SL070030125 the quality-controlled hourly data with dates given as the nth 186SL070030126 day of the year starting from 1 January: 186SL070030127 1) a Completeness Index (CI) based on the percentage of hours 186SL070030128 with available data, 186SL070030129 2) a list of gaps longer than a day, 186SL070030130 3) a summary of days with consecutive missing or obviously 186SL070030131 wrong data in a time span longer than 6 but less than 25 186SL070030132 hours that have been replaced, with hours in parentheses, and 186SL070030133 4) a summary of days with questionable fluctuations in the 186SL070030134 residual series. Fluctuations within the residuals are 186SL070030135 considered significant and are noted if they are greater than 186SL070030136 25 cm. This policy has changed slightly as of October 1992: 186SL070030137 only suspicious fluctuations due to obvious instrumentation 186SL070030138 problems are noted. Minor timing drifts are no longer 186SL070030139 included in the list of questionable days. 186SL070030140 186SL070030141 Note : If the predicted tides poorly model the observed heights 186SL070030142 due to the inability of the tidal analysis to completely resolv 186SL070030143 the non-linear shallow water effects, the residuals are not 186SL070030144 suitable for assessing the data quality. Instead, a subjective 186SL070030145 comment on the quality of the data is provided. 186SL070030146 186SL070030147 *The predicted tides are obtained with the use of a harmonic 186SL070030148 analysis program (Foreman, 1977) which is executed on a year 186SL070030149 of apparently good data for a given station. The Predicted 186SL070030150 Tide Method for filling gaps consists of statistically 186SL070030151 comparing the predicted tides to the observed data and 186SL070030152 shifting the predicted tides in time to correct for timing 186SL070030153 differences. Then the linear interpolation between hourly 186SL070030154 values at the end points of the gap in the residual series is 186SL070030155 added to the corresponding corrected predicted tide data to 186SL070030156 obtain interpolated values over the span of the gap. 186SL070030157 186SL070030158 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL070030159 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL070030160 186SL070030161 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL070030162 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL070030163 Victoria B.C. Pacific Marine Science Report 77-10. 186SL070030164 186SL07006 19731 1541000 1578000 1532000 1555000 1521000 1533000 186SL07006 19732 159600099999999 1570070 1555000 1568000 1575000 186SL07006 19741 1651040 1670060 1504050 15140609999999999999999 186SL07006 19742 159606099999999 1546030 151404099999999 1545000 186SL07006 19751 99999999 1572000 1652000 1673000 1691000 1650000 186SL07006 19752 1581000 1651000 1679000 1668030 1717000 1673000 186SL07006 19761 1623000 1563000 1565000 1599000 1520000 1533000 186SL07006 19762 1558000 1545000 1550000 1555000 1520000 1503000 186SL07006 19771 1484000 1481000 1418000 1457000 1461000 1547000 186SL07006 19772 1595000 152100099999999 1574000 1642030 1551000 186SL07006 19781 9999999999999999 1605010 1535000 1471000 1648000 186SL07006 19782 1746000 1672000 1696000 1670000 1597000 1613010 186SL07006 19791 9999999999999999 1578000 1475000 1575000 1421000 186SL07006 19792 1499000 1587000 1572000 1490000 1663000 1603000 186SL07006 19801 1533000 1521000 1490000 1581000 1425000 1594000 186SL07006 19802 1595000 1701000 1730000 1578000 1536000 1648000 186SL07006 19811 1574000 163500099999999999999999999999999999999 186SL07006 19812 999999999999999999999999999999999999999999999999 186SL07006 19821 999999999999999999999999999999999999999999999999 186SL07006 19822 9999999999999999 1574000 1639000 1466000 1470000 186SL07006 19831 1498000 1481000 1483000 1512000 1421000 1420000 186SL07006 19832 1470000 1551000 1797000 1761000 1709000 1698000 186SL07006 19841 1712000 1676000 1700000 1648000 1728000 1709000 186SL07006 19842 1579000 1757000 1798000 1661000 1692000 1601000 186SL07006 19851 1468000 1636000 1626000 1571000 1622000 1658000 186SL07006 19852 1720000 1646000 1608000 1662000 1577000 1530000 186SL07006 19861 1587000 1544000 1526000 1610000 1483000 1448000 186SL07006 19862 1505000 1572000 1577000 1485000 1516000 1537000 186SL07006 19871 1549000 1582000 1611000 1654000 1566000 1621000 186SL07006 19872 1713000 1739000 1675000 1627000 1549000 1450000 186SL07006 19881 1495000 1581000 1523000 1622000 1656000 1495000 186SL07006 19882 1650000 1756000 1686000 1790000 1762000 1534000 186SL07006 19891 1479000 1501000 1484000 1504000 1513000 1624000 186SL07006 19892 1513000 1395000 1662000 1458000 1472000 1560000 186SL07006 19901 1501000 1502000 1514000 1447000 1551000 1637000 186SL07006 19902 1727000 1684000 1622000 1614000 1519000 1632000 186SL07006 19911 1593000 1615000 1597000 1645000 1517000 1457000 186SL07006 19912 1711000 1510000 1509000 1538000 1672000 1601000 186SL07006 19921 1537000 1510000 1524000 1455000 1495000 1362000 186SL07006 19922 1563000 1636000 1636000 1677000 1547000 1592000