186SL0702110157101 054A 19730101 19911231 0727N 15151E 2 00000R 0000 MM 186SL0702210157101 Truk Fd St Micronesia National Ocean Service 186SL070230001 186SL070230002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL070230003 by the 186SL070230004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL070230005 JOINT ARCHIVE FOR SEA LEVEL 186SL070230006 186SL070230007Station : Chuuk Latitude: 07 27.0N 186SL070230008Country : Fed. States Micronesia Longitude: 151 51.0E 186SL070230009JASL # : 054A Time Meridian: 150E (GMT + 10 hr) 186SL070230010GLOSS # : 116 TOGA #: P038 NODC #: 10157101 186SL070230011Contributor : National Ocean Service (NOS) 186SL070230012 National Ocean. and Atmos. Administration (NOAA) 186SL070230013 Rockville, Maryland 20852 186SL070230014Originator : same 186SL070230015Original Data: analog (standard); digital (ADR and NGWLMS) 186SL070230016Instrmnt Type: standard mechanical (1973-1974); analog-to-digital 186SL070230017 (ADR) recorder (1975-1990); Aquatrak acoustic 186SL070230018 gauge, NOAA Next Generation Water Level Measuring 186SL070230019 System (NGWLMS) (1991-) 186SL070230020Digitzd Intvl: hourly (standard); six-minute (adr and NGWLMS) 186SL070230021Present Data : Hourly, daily, and monthly values obtained by: 186SL070230022 Hourly : The original digitizing interval was hourly 186SL070230023 (standard); spot sampling on the hour (adr/NGWLMS) 186SL070230024 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL070230025 centered on noon applied to the hourly data 186SL070230026 with respective periods of the 95, 50, and 5% 186SL070230027 amplitude points at 124.0, 60.2, and 40.2 hours 186SL070230028 Monthly: Simple average of all daily values; calculated if 186SL070230029 7 or fewer days are missing 186SL070230030Span of data : 01 Jan 1973 - 31 Dec 1991 186SL070230031Gaps > 1 mon : 31 Oct - 31 Dec 1975; 8 Sep - 23 Oct 1976; 186SL070230032 01 Nov 1987 - 21 Feb 1988;23 Nov 1990 - 07 Feb 1991 186SL070230033Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 186SL070230034Units : millimeters Missing Data Flag :99999 186SL070230035Refernce Levl: All heights have been referred to the station tide 186SL070230036 staff zero which is linked to fixed bench marks 186SL070230037Comment : The daily and monthly means reveal no apparent 186SL070230038 reference level changes or trends. The timing 186SL070230039 appears to be off by roughly 6 minutes from 186SL070230040 Sep - Dec 1991. 186SL070230041 186SL070230042 CI MISSING REPLACED GAPS QUESTIONABLE 186SL070230043YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL070230044---- --- -------------------- --------------- -------------------- 186SL0702300451973 98 265-266,363-365 (02)226-(17)226 none 186SL070230046 (23)227-(09)228 186SL070230047 (12)231-(20)231 186SL070230048 (07)309-(21)309 186SL070230049 (15)326-(22)326 186SL0702300501974 100 none (22)347-(09)348 none 186SL070230051 (22)348-(12)349 186SL070230052 (14)365-(23)365 186SL0702300531975 83 304-365 none none 186SL0702300541976 75 25-47,63-69, (05)251-(13)251 none 186SL070230055 72-83,252-297, 186SL070230056 360-361 186SL0702300571977 91 8-9,11-29, none none 186SL070230058 49-52,83-91 186SL0702300591978 94 10-12,66-69, (06)046-(05)047 none 186SL070230060 92-93,274-286 (01)100-(23)100 186SL070230061 (10)106-(21)106 186SL0702300621979 99 37-38,102-105 none none 186SL0702300631980 100 none none none 186SL0702300641981 94 222-243 none none 186SL0702300651982 100 none none none 186SL0702300661983 100 none none none 186SL0702300671984 100 none none none 186SL0702300681985 100 none none none 186SL0702300691986 100 none none none 186SL0702300701987 78 260-265,276-278, none 274-275 186SL070230071 305-365 186SL0702300721988 86 1-52 none 330-331 186SL0702300731989 100 none none none 186SL0702300741990 90 327-365 none none 186SL0702300751991 77 1-38,107-127,199- none none 186SL070230076 223,245-246,365 186SL070230077 186SL070230078 QUALITY ASSESSMENT POLICY 186SL070230079 186SL070230080 The quality assessment is mostly based on the residuals 186SL070230081 (observed data minus predicted tides) of the hourly data. This 186SL070230082 assessment also applies to the daily and monthly data since 186SL070230083 they were derived from the quality-controlled hourly data. 186SL070230084 186SL070230085 The following abbreviations are used in the assessment: 186SL070230086 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL070230087 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL070230088 research program; NODC - National Oceanographic Data Center; 186SL070230089 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL070230090 Gaps > 1 mon - missing data in a span greater than one month; 186SL070230091 Refernce - reference. 186SL070230092 186SL070230093 The following corrections are made to the hourly data 186SL070230094 prior to this assessment: 186SL070230095 1) Gaps or obviously wrong data points in a span less than 186SL070230096 25 hours are filled by the predicted tide method*. 186SL070230097 2) Timing errors of exact increments of an hour are corrected 186SL070230098 by shifting the data. 186SL070230099 3) Reference level shifts are only corrected after information 186SL070230100 from tide staff readings or comparative readings with a fixed 186SL070230101 bench mark are checked to verify that the shift was not a 186SL070230102 natural event. If comparative readings are missing or 186SL070230103 incomplete, comparisons of the data with nearby stations 186SL070230104 may warrant the adjustment of some obvious shifts. 186SL070230105 4) Data with unresolved datum shifts are not disseminated. 186SL070230106 However, if sufficient time spans of data are available before 186SL070230107 or after the year(s) with the unresolved shift(s), a subset of 186SL070230108 quality assured data is made available. Thus, the Span field 186SL070230109 in the Quality Assessment may not match the span of the 186SL070230110 distribution data set. As the questionable datum shifts are 186SL070230111 resolved, the data set will be updated. Although this policy 186SL070230112 adds some complexity, it allows more rapid dissemination of 186SL070230113 at least the quality assured years. 186SL070230114 186SL070230115 For each year, the following information is documented from 186SL070230116 the quality-controlled hourly data with dates given as the nth 186SL070230117 day of the year starting from 1 January: 186SL070230118 1) a Completeness Index (CI) based on the percentage of hours 186SL070230119 with available data, 186SL070230120 2) a list of gaps longer than a day, 186SL070230121 3) a summary of days with consecutive missing or obviously 186SL070230122 wrong data in a time span longer than 6 but less than 25 186SL070230123 hours that have been replaced, with hours in parentheses, and 186SL070230124 4) a summary of days with questionable fluctuations in the 186SL070230125 residual series. Fluctuations within the residuals are 186SL070230126 considered significant and are noted if they are greater than 186SL070230127 25 cm. This policy has changed slightly as of October 1992: 186SL070230128 only suspicious fluctuations due to obvious instrumentation 186SL070230129 problems are noted. Minor timing drifts are no longer 186SL070230130 included in the list of questionable days. 186SL070230131 186SL070230132 Note : If the predicted tides poorly model the observed heights 186SL070230133 due to the inability of the tidal analysis to completely resolv 186SL070230134 the non-linear shallow water effects, the residuals are not 186SL070230135 suitable for assessing the data quality. Instead, a subjective 186SL070230136 comment on the quality of the data is provided. 186SL070230137 186SL070230138 *The predicted tides are obtained with the use of a harmonic 186SL070230139 analysis program (Foreman, 1977) which is executed on a year 186SL070230140 of apparently good data for a given station. The Predicted 186SL070230141 Tide Method for filling gaps consists of statistically 186SL070230142 comparing the predicted tides to the observed data and 186SL070230143 shifting the predicted tides in time to correct for timing 186SL070230144 differences. Then the linear interpolation between hourly 186SL070230145 values at the end points of the gap in the residual series is 186SL070230146 added to the corresponding corrected predicted tide data to 186SL070230147 obtain interpolated values over the span of the gap. 186SL070230148 186SL070230149 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL070230150 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL070230151 186SL070230152 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL070230153 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL070230154 Victoria B.C. Pacific Marine Science Report 77-10. 186SL070230155 186SL07026 19731 921000 1002000 1146000 1175000 1178000 1144000 186SL07026 19732 1164000 1142000 1189030 1209000 1189000 1168040 186SL07026 19741 1152000 1143000 1083000 1152000 1105000 1068000 186SL07026 19742 1105000 1182000 1188000 1236000 1169000 1037000 186SL07026 19751 1064000 1190000 1248000 1210000 1189000 1184000 186SL07026 19752 1149000 1123000 1217000 13040109999999999999999 186SL07026 19761 11700709999999999999999 1120000 1010000 980000 186SL07026 19762 983000 10130009999999999999999 890000 888020 186SL07026 19771 99999999 109504099999999 1190010 1154000 1162000 186SL07026 19772 1153000 1100000 1068000 1076000 1001000 972000 186SL07026 19781 984030 1012000 1122040 1142020 1220000 1151000 186SL07026 19782 1166000 1152000 116500099999999 1159000 1096020 186SL07026 19791 1064000 1088030 1151000 1164060 1145000 1135000 186SL07026 19792 1134000 1091000 1119000 1011000 1036000 1016000 186SL07026 19801 961000 990000 1089000 1127000 1051000 1052000 186SL07026 19802 1003000 1010000 1024000 1045000 948000 942000 186SL07026 19811 1038000 1142000 1092000 1130000 1112000 1163000 186SL07026 19812 115000099999999 1145000 1153000 1150000 1064000 186SL07026 19821 1142000 1137000 1164000 1099000 1054000 1041000 186SL07026 19822 926000 917000 936000 869000 874000 836000 186SL07026 19831 890000 943000 981000 1125000 1187000 1174000 186SL07026 19832 1154000 1154000 1148000 1178000 1160000 1120000 186SL07026 19841 1051000 1117000 1161000 1221000 1248000 1204000 186SL07026 19842 1196000 1167000 1143000 1157000 1100000 1152000 186SL07026 19851 1162000 1244000 1231000 1185000 1168000 1133000 186SL07026 19852 1093000 1077000 1098000 1074000 1067000 1058000 186SL07026 19861 1121000 1172000 1129000 1217000 1123000 1086000 186SL07026 19862 1083000 1110000 1082000 1062000 1042000 940010 186SL07026 19871 922000 1076000 1012000 1082000 1123000 1075000 186SL07026 19872 1036000 979000 965070 9990309999999999999999 186SL07026 19881 9999999999999999 1143000 1154000 1181000 1202000 186SL07026 19882 1181000 1162000 1237000 1305000 1391000 1274000 186SL07026 19891 1235000 1193000 1157000 1178000 1162000 1141000 186SL07026 19892 1151000 1164000 1163000 1161000 1166000 1075000 186SL07026 19901 1068000 1007000 1072000 1128000 1147000 1153000 186SL07026 19902 1106000 1122000 1064000 10800009999999999999999 186SL07026 19911 99999999 1144070 110000099999999 1017070 1036000 186SL07026 19912 9999999999999999 1016020 977000 957000 891010