186SL0866170153902 012C 19881003 19901231 0351N 15922W 2 00000R 0000 MM 186SL0866270153902 Fanning-C Rep. of Kiribati TOGA Sea Level Center 186SL086630001 186SL086630002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL086630003 by the 186SL086630004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL086630005 JOINT ARCHIVE FOR SEA LEVEL 186SL086630006 186SL086630007Station : Fanning-C Latitude: 03 51.4N 186SL086630008Country : Republic of Kiribati Longitude: 159 21.9W 186SL086630009JASL # : 012C Time Meridian: 150W (GMT - 10 hr) 186SL086630010GLOSS # : 147 TOGA #: P061 NODC #: 70153902 186SL086630011Contributor : TOGA Sea Level Center 186SL086630012 1000 Pope Rd. MSB 317 186SL086630013 Honolulu, Hawaii 96822 186SL086630014Originator : Dept. of Oceanography 186SL086630015 University of Hawaii 186SL086630016 1000 Pope Rd. MSB 317 186SL086630017 Honolulu, Hawaii 96822 186SL086630018Original Data: digital 186SL086630019Instrmnt Type: Fischer and Porter Analog-to-Digital Recorder 186SL086630020Digitzd Intvl: 15 minutes 186SL086630021Present Data : Hourly, daily, and monthly values obtained by: 186SL086630022 Hourly : Three-point Hanning filter centered on the hour 186SL086630023 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL086630024 centered on noon applied to the hourly data 186SL086630025 with respective periods of the 95, 50, and 5% 186SL086630026 amplitude points at 124.0, 60.2, and 40.2 hours 186SL086630027 Monthly: Simple average of all daily values; calculated if 186SL086630028 7 or fewer days are missing 186SL086630029Span of data : 03 Oct 1988 - 31 Dec 1990 186SL086630030Gaps > 1 mon : 11 Jun - 05 Dec 1989 186SL086630031Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 186SL086630032Units : millimeters Missing Data Flag :99999 186SL086630033Refernce Levl: All heights have been referred to the station tide 186SL086630034 staff zero which is linked to fixed bench marks 186SL086630035Comment : The daily and monthly means reveal no apparent 186SL086630036 changes in the reference level and agree with 186SL086630037 Christmas. The timing is poor from late April to 186SL086630038 Oct. 1990 due to sand intruding the stilling well. 186SL086630039 186SL086630040 CI MISSING REPLACED GAPS QUESTIONABLE 186SL086630041YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL086630042---- --- -------------------- --------------- -------------------- 186SL0866300431988 24 none none none 186SL0866300441989 52 162-339 none none 186SL0866300451990 100 none none 129-133,163-165,172- 186SL086630046 176,189-193,204-205, 186SL086630047 218-254 186SL086630048 186SL086630049 QUALITY ASSESSMENT POLICY 186SL086630050 186SL086630051 The quality assessment is mostly based on the residuals 186SL086630052 (observed data minus predicted tides) of the hourly data. This 186SL086630053 assessment also applies to the daily and monthly data since 186SL086630054 they were derived from the quality-controlled hourly data. 186SL086630055 186SL086630056 The following abbreviations are used in the assessment: 186SL086630057 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL086630058 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL086630059 research program; NODC - National Oceanographic Data Center; 186SL086630060 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL086630061 Gaps > 1 mon - missing data in a span greater than one month; 186SL086630062 Refernce - reference. 186SL086630063 186SL086630064 The following corrections are made to the hourly data 186SL086630065 prior to this assessment: 186SL086630066 1) Gaps or obviously wrong data points in a span less than 186SL086630067 25 hours are filled by the predicted tide method*. 186SL086630068 2) Timing errors of exact increments of an hour are corrected 186SL086630069 by shifting the data. 186SL086630070 3) Reference level shifts are only corrected after information 186SL086630071 from tide staff readings or comparative readings with a fixed 186SL086630072 bench mark are checked to verify that the shift was not a 186SL086630073 natural event. If comparative readings are missing or 186SL086630074 incomplete, comparisons of the data with nearby stations 186SL086630075 may warrant the adjustment of some obvious shifts. 186SL086630076 4) Data with unresolved datum shifts are not disseminated. 186SL086630077 However, if sufficient time spans of data are available before 186SL086630078 or after the year(s) with the unresolved shift(s), a subset of 186SL086630079 quality assured data is made available. Thus, the Span field 186SL086630080 in the Quality Assessment may not match the span of the 186SL086630081 distribution data set. As the questionable datum shifts are 186SL086630082 resolved, the data set will be updated. Although this policy 186SL086630083 adds some complexity, it allows more rapid dissemination of 186SL086630084 at least the quality assured years. 186SL086630085 186SL086630086 For each year, the following information is documented from 186SL086630087 the quality-controlled hourly data with dates given as the nth 186SL086630088 day of the year starting from 1 January: 186SL086630089 1) a Completeness Index (CI) based on the percentage of hours 186SL086630090 with available data, 186SL086630091 2) a list of gaps longer than a day, 186SL086630092 3) a summary of days with consecutive missing or obviously 186SL086630093 wrong data in a time span longer than 6 but less than 25 186SL086630094 hours that have been replaced, with hours in parentheses, and 186SL086630095 4) a summary of days with questionable fluctuations in the 186SL086630096 residual series. Fluctuations within the residuals are 186SL086630097 considered significant and are noted if they are greater than 186SL086630098 25 cm. This policy has changed slightly as of October 1992: 186SL086630099 only suspicious fluctuations due to obvious instrumentation 186SL086630100 problems are noted. Minor timing drifts are no longer 186SL086630101 included in the list of questionable days. 186SL086630102 186SL086630103 Note : If the predicted tides poorly model the observed heights 186SL086630104 due to the inability of the tidal analysis to completely resolv 186SL086630105 the non-linear shallow water effects, the residuals are not 186SL086630106 suitable for assessing the data quality. Instead, a subjective 186SL086630107 comment on the quality of the data is provided. 186SL086630108 186SL086630109 *The predicted tides are obtained with the use of a harmonic 186SL086630110 analysis program (Foreman, 1977) which is executed on a year 186SL086630111 of apparently good data for a given station. The Predicted 186SL086630112 Tide Method for filling gaps consists of statistically 186SL086630113 comparing the predicted tides to the observed data and 186SL086630114 shifting the predicted tides in time to correct for timing 186SL086630115 differences. Then the linear interpolation between hourly 186SL086630116 values at the end points of the gap in the residual series is 186SL086630117 added to the corresponding corrected predicted tide data to 186SL086630118 obtain interpolated values over the span of the gap. 186SL086630119 186SL086630120 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL086630121 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL086630122 186SL086630123 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL086630124 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL086630125 Victoria B.C. Pacific Marine Science Report 77-10. 186SL086630126 186SL08666 19881 999999999999999999999999999999999999999999999999 186SL08666 19882 999999999999999999999999 856030 853000 890000 186SL08666 19891 863000 842000 885000 857000 88700099999999 186SL08666 19892 9999999999999999999999999999999999999999 995050 186SL08666 19901 1046000 1066000 1013000 989000 915000 959000 186SL08666 19902 1003000 1036000 1104000 1053000 1104000 1088000