186SL0815150148001 031A 19820401 19931231 0856S 14005W 2 00000R 0000 MM 186SL0815250148001 Nuku Hiva French Polynesia TOGA Sea Level Center 186SL081530001 186SL081530002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL081530003 by the 186SL081530004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL081530005 JOINT ARCHIVE FOR SEA LEVEL 186SL081530006 186SL081530007Station : Nuku Hiva,Marquesas Is. Latitude: 08 55.8S 186SL081530008Country : French Polynesia Longitude: 140 04.9W 186SL081530009JASL # : 031A Time Meridian: 135W (GMT - 9 hr) 186SL081530010GLOSS # : 142 TOGA #: P066 NODC #: 50148001 186SL081530011Contributor : TOGA Sea Level Center 186SL081530012 1000 Pope Rd. MSB 317 186SL081530013 Honolulu, Hawaii 96822 186SL081530014Originator : Dept. of Oceanography 186SL081530015 University of Hawaii 186SL081530016 1000 Pope Rd. MSB 317 186SL081530017 Honolulu, Hawaii 96822 186SL081530018Original Data: digital 186SL081530019Instrmnt Type: 1. (1982-1983,1986-present) Leupold and 186SL081530020 Stevens Analog-to-Digital Recorder (ADR); 186SL081530021 2. (4/1986-present) Handar Encoder (ENC) 186SL081530022 Primary gauge: ADR:1982-90, ENC 1991- 186SL081530023Digitzd Intvl: 15 (ADR); 10 (ENC) minutes 186SL081530024Present Data : Hourly, daily, and monthly values obtained by: 186SL081530025 Hourly : (pre-1987) Nine-point triangular filter centered 186SL081530026 on the hour with respective periods of the 95, 50, 186SL081530027 and 5% amplitude point of the filter response at 186SL081530028 623.6, 177.0, and 103.7 minutes;(1987+) three-point 186SL081530029 Hanning filter centered on the hour 186SL081530030 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL081530031 centered on noon applied to the hourly data 186SL081530032 with respective periods of the 95, 50, and 5% 186SL081530033 amplitude points at 124.0, 60.2, and 40.2 hours 186SL081530034 Monthly: Simple average of all daily values; calculated if 186SL081530035 7 or fewer days are missing 186SL081530036Span of data : 01 Apr 1982 - 31 Dec 1993 186SL081530037Gaps > 1 mon : 01 Jan 1983 - 11 Feb 1986;03 Nov 1988 - 02 Feb 1989 186SL081530038Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 186SL081530039Units : millimeters Missing Data Flag :99999 186SL081530040Refernce Levl: All heights have been referred to the station tide 186SL081530041 staff zero which is linked to fixed bench marks 186SL081530042Comment : The daily means show some similarity to the daily 186SL081530043 means of a neighboring station, Penrhyn, and 186SL081530044 reveal no obvious reference level changes. 186SL081530045 186SL081530046 CI MISSING REPLACED GAPS QUESTIONABLE 186SL081530047YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL081530048---- --- -------------------- --------------- -------------------- 186SL0815300491982 70 170-179,335-341 none none 186SL0815300501983 0 1-365 none none 186SL0815300511984 0 1-366 none none 186SL0815300521985 0 1-365 none none 186SL0815300531986 89 none none none 186SL0815300541987 100 none none none 186SL0815300551988 84 308-366 none none 186SL0815300561989 84 1-60 none none 186SL0815300571990 100 none none none 186SL0815300581991 100 none none none 186SL0815300591992 99 100-103 none none 186SL0815300601993 99 41-42 none none 186SL081530061 186SL081530062 QUALITY ASSESSMENT POLICY 186SL081530063 186SL081530064 The quality assessment is mostly based on the residuals 186SL081530065 (observed data minus predicted tides) of the hourly data. This 186SL081530066 assessment also applies to the daily and monthly data since 186SL081530067 they were derived from the quality-controlled hourly data. 186SL081530068 186SL081530069 The following abbreviations are used in the assessment: 186SL081530070 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL081530071 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL081530072 research program; NODC - National Oceanographic Data Center; 186SL081530073 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL081530074 Gaps > 1 mon - missing data in a span greater than one month; 186SL081530075 Refernce - reference. 186SL081530076 186SL081530077 The following corrections are made to the hourly data 186SL081530078 prior to this assessment: 186SL081530079 1) Gaps or obviously wrong data points in a span less than 186SL081530080 25 hours are filled by the predicted tide method*. 186SL081530081 2) Timing errors of exact increments of an hour are corrected 186SL081530082 by shifting the data. 186SL081530083 3) Reference level shifts are only corrected after information 186SL081530084 from tide staff readings or comparative readings with a fixed 186SL081530085 bench mark are checked to verify that the shift was not a 186SL081530086 natural event. If comparative readings are missing or 186SL081530087 incomplete, comparisons of the data with nearby stations 186SL081530088 may warrant the adjustment of some obvious shifts. 186SL081530089 4) Data with unresolved datum shifts are not disseminated. 186SL081530090 However, if sufficient time spans of data are available before 186SL081530091 or after the year(s) with the unresolved shift(s), a subset of 186SL081530092 quality assured data is made available. Thus, the Span field 186SL081530093 in the Quality Assessment may not match the span of the 186SL081530094 distribution data set. As the questionable datum shifts are 186SL081530095 resolved, the data set will be updated. Although this policy 186SL081530096 adds some complexity, it allows more rapid dissemination of 186SL081530097 at least the quality assured years. 186SL081530098 186SL081530099 For each year, the following information is documented from 186SL081530100 the quality-controlled hourly data with dates given as the nth 186SL081530101 day of the year starting from 1 January: 186SL081530102 1) a Completeness Index (CI) based on the percentage of hours 186SL081530103 with available data, 186SL081530104 2) a list of gaps longer than a day, 186SL081530105 3) a summary of days with consecutive missing or obviously 186SL081530106 wrong data in a time span longer than 6 but less than 25 186SL081530107 hours that have been replaced, with hours in parentheses, and 186SL081530108 4) a summary of days with questionable fluctuations in the 186SL081530109 residual series. Fluctuations within the residuals are 186SL081530110 considered significant and are noted if they are greater than 186SL081530111 25 cm. This policy has changed slightly as of October 1992: 186SL081530112 only suspicious fluctuations due to obvious instrumentation 186SL081530113 problems are noted. Minor timing drifts are no longer 186SL081530114 included in the list of questionable days. 186SL081530115 186SL081530116 Note : If the predicted tides poorly model the observed heights 186SL081530117 due to the inability of the tidal analysis to completely resolv 186SL081530118 the non-linear shallow water effects, the residuals are not 186SL081530119 suitable for assessing the data quality. Instead, a subjective 186SL081530120 comment on the quality of the data is provided. 186SL081530121 186SL081530122 *The predicted tides are obtained with the use of a harmonic 186SL081530123 analysis program (Foreman, 1977) which is executed on a year 186SL081530124 of apparently good data for a given station. The Predicted 186SL081530125 Tide Method for filling gaps consists of statistically 186SL081530126 comparing the predicted tides to the observed data and 186SL081530127 shifting the predicted tides in time to correct for timing 186SL081530128 differences. Then the linear interpolation between hourly 186SL081530129 values at the end points of the gap in the residual series is 186SL081530130 added to the corresponding corrected predicted tide data to 186SL081530131 obtain interpolated values over the span of the gap. 186SL081530132 186SL081530133 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL081530134 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL081530135 186SL081530136 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL081530137 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL081530138 Victoria B.C. Pacific Marine Science Report 77-10. 186SL081530139 186SL08156 19821 999999999999999999999999 1566000 156500099999999 186SL08156 19822 1615000 1642000 1659000 1645000 1651000 1620070 186SL08156 19831 999999999999999999999999999999999999999999999999 186SL08156 19832 999999999999999999999999999999999999999999999999 186SL08156 19841 999999999999999999999999999999999999999999999999 186SL08156 19842 999999999999999999999999999999999999999999999999 186SL08156 19851 999999999999999999999999999999999999999999999999 186SL08156 19852 999999999999999999999999999999999999999999999999 186SL08156 19861 9999999999999999 1645000 1591000 1531000 1529000 186SL08156 19862 1555000 1546000 1565000 1554000 1614000 1594000 186SL08156 19871 1631000 1674000 1637000 1593000 1577000 1591000 186SL08156 19872 1606000 1632000 1652000 1648000 1677000 1657000 186SL08156 19881 1645000 1659000 1655000 1624000 1587000 1551000 186SL08156 19882 1530000 1523000 1493000 15260009999999999999999 186SL08156 19891 9999999999999999 1470020 1436000 1436000 1439000 186SL08156 19892 1493000 1525000 1555000 1571000 1573000 1549000 186SL08156 19901 1627000 1623000 1645000 1622000 1610000 1617000 186SL08156 19902 1604000 1632000 1621000 1613000 1618000 1623000 186SL08156 19911 1668000 1677000 1665000 1640000 1632000 1602000 186SL08156 19912 1631000 1653000 1691000 1708000 1682000 1684000 186SL08156 19921 1696000 1679000 1694000 1624040 1595000 1602000 186SL08156 19922 1573000 1592000 1586000 1585000 1582000 1561000 186SL08156 19931 1564000 1551020 1536000 1536000 1513000 1535000 186SL08156 19932 1548000 1573000 1566000 1585000 1561000 1564000