186SL0913134171101 074A 19840801 19851231 4144S 17136E 2 00000R 0000 MM 186SL0913234171101 Westport New Zealand Royal New Zealand Navy 186SL091330001 186SL091330002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL091330003 by the 186SL091330004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL091330005 JOINT ARCHIVE FOR SEA LEVEL 186SL091330006 186SL091330007Station : Westport Latitude: 41 44.0S 186SL091330008Country : New Zealand Longitude: 171 36.0E 186SL091330009JASL # : 074A Time Meridian: 180E (GMT + 12 hr) 186SL091330010GLOSS # : none TOGA #: none NODC #: 34171101 186SL091330011Contributor : Royal New Zealand Navy - Hydrographic Office 186SL091330012 Burns Avenue 186SL091330013 Takapuna, Auckland, New Zealand 186SL091330014Originator : same 186SL091330015Original Data: digital 186SL091330016Instrmnt Type: DSIR (NZ) Kainga pressure transducer, Campbell 186SL091330017 CR10 data logger 186SL091330018Digitzd Intvl: operator selective, normally 5 minutes 186SL091330019Present Data : Hourly, daily, and monthly values obtained by: 186SL091330020 Hourly : manual extraction of hourlies from digital record 186SL091330021 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL091330022 centered on noon applied to the hourly data 186SL091330023 with respective periods of the 95, 50, and 5% 186SL091330024 amplitude points at 124.0, 60.2, and 40.2 hours 186SL091330025 Monthly: Simple average of all daily values; calculated if 186SL091330026 7 or fewer days are missing 186SL091330027Span of data : 01 Aug 1984 - 31 Dec 1985 186SL091330028Gaps > 1 mon : none 186SL091330029Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 186SL091330030Units : millimeters Missing Data Flag :99999 186SL091330031Refernce Levl: The sea level heights are referred to the zero 186SL091330032 point assigned to the tide staff. 186SL091330033Comment : The daily and monthly values do not show any 186SL091330034 obvious shifts or trends. The daily values show 186SL091330035 large peaks of a few days duration associated with 186SL091330036 extreme weather. 186SL091330037 186SL091330038 CI MISSING REPLACED GAPS QUESTIONABLE 186SL091330039YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL091330040---- --- -------------------- --------------- -------------------- 186SL0913300411984 42 none none none 186SL0913300421985 99 365 (01)148-(11)148 none 186SL091330043 (16)149-(23)149 186SL091330044 (01)172-(08)172 186SL091330045 186SL091330046 QUALITY ASSESSMENT POLICY 186SL091330047 186SL091330048 The quality assessment is mostly based on the residuals 186SL091330049 (observed data minus predicted tides) of the hourly data. This 186SL091330050 assessment also applies to the daily and monthly data since 186SL091330051 they were derived from the quality-controlled hourly data. 186SL091330052 186SL091330053 The following abbreviations are used in the assessment: 186SL091330054 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL091330055 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL091330056 research program; NODC - National Oceanographic Data Center; 186SL091330057 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL091330058 Gaps > 1 mon - missing data in a span greater than one month; 186SL091330059 Refernce - reference. 186SL091330060 186SL091330061 The following corrections are made to the hourly data 186SL091330062 prior to this assessment: 186SL091330063 1) Gaps or obviously wrong data points in a span less than 186SL091330064 25 hours are filled by the predicted tide method*. 186SL091330065 2) Timing errors of exact increments of an hour are corrected 186SL091330066 by shifting the data. 186SL091330067 3) Reference level shifts are only corrected after information 186SL091330068 from tide staff readings or comparative readings with a fixed 186SL091330069 bench mark are checked to verify that the shift was not a 186SL091330070 natural event. If comparative readings are missing or 186SL091330071 incomplete, comparisons of the data with nearby stations 186SL091330072 may warrant the adjustment of some obvious shifts. 186SL091330073 4) Data with unresolved datum shifts are not disseminated. 186SL091330074 However, if sufficient time spans of data are available before 186SL091330075 or after the year(s) with the unresolved shift(s), a subset of 186SL091330076 quality assured data is made available. Thus, the Span field 186SL091330077 in the Quality Assessment may not match the span of the 186SL091330078 distribution data set. As the questionable datum shifts are 186SL091330079 resolved, the data set will be updated. Although this policy 186SL091330080 adds some complexity, it allows more rapid dissemination of 186SL091330081 at least the quality assured years. 186SL091330082 186SL091330083 For each year, the following information is documented from 186SL091330084 the quality-controlled hourly data with dates given as the nth 186SL091330085 day of the year starting from 1 January: 186SL091330086 1) a Completeness Index (CI) based on the percentage of hours 186SL091330087 with available data, 186SL091330088 2) a list of gaps longer than a day, 186SL091330089 3) a summary of days with consecutive missing or obviously 186SL091330090 wrong data in a time span longer than 6 but less than 25 186SL091330091 hours that have been replaced, with hours in parentheses, and 186SL091330092 4) a summary of days with questionable fluctuations in the 186SL091330093 residual series. Fluctuations within the residuals are 186SL091330094 considered significant and are noted if they are greater than 186SL091330095 25 cm. This policy has changed slightly as of October 1992: 186SL091330096 only suspicious fluctuations due to obvious instrumentation 186SL091330097 problems are noted. Minor timing drifts are no longer 186SL091330098 included in the list of questionable days. 186SL091330099 186SL091330100 Note : If the predicted tides poorly model the observed heights 186SL091330101 due to the inability of the tidal analysis to completely resolv 186SL091330102 the non-linear shallow water effects, the residuals are not 186SL091330103 suitable for assessing the data quality. Instead, a subjective 186SL091330104 comment on the quality of the data is provided. 186SL091330105 186SL091330106 *The predicted tides are obtained with the use of a harmonic 186SL091330107 analysis program (Foreman, 1977) which is executed on a year 186SL091330108 of apparently good data for a given station. The Predicted 186SL091330109 Tide Method for filling gaps consists of statistically 186SL091330110 comparing the predicted tides to the observed data and 186SL091330111 shifting the predicted tides in time to correct for timing 186SL091330112 differences. Then the linear interpolation between hourly 186SL091330113 values at the end points of the gap in the residual series is 186SL091330114 added to the corresponding corrected predicted tide data to 186SL091330115 obtain interpolated values over the span of the gap. 186SL091330116 186SL091330117 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL091330118 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL091330119 186SL091330120 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL091330121 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL091330122 Victoria B.C. Pacific Marine Science Report 77-10. 186SL091330123 186SL09136 19841 999999999999999999999999999999999999999999999999 186SL09136 19842 99999999 1929000 1889000 1935000 1924000 1999000 186SL09136 19851 1963000 1852000 1908000 1940000 1938000 2049000 186SL09136 19852 2001000 1910000 1945000 1879000 1914000 2021010