186SL0679170151701 011A 19551201 19720401 0159N 15729W 2 00000R 0000 MM 186SL0679270151701 Christmas-A Rep. of Kiribati Scripps Inst. Ocean. 186SL067930001 186SL067930002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL067930003 by the 186SL067930004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL067930005 JOINT ARCHIVE FOR SEA LEVEL 186SL067930006 186SL067930007Station : Christmas-A Latitude: 01 59.1N 186SL067930008Country : Republic of Kiribati Longitude: 157 28.6W 186SL067930009JASL # : 011A Time Meridian: 150W (GMT - 10 hr) 186SL067930010GLOSS # : 146 TOGA #: P062 NODC #: 70151701 186SL067930011Contributor : Scripps Institute of Oceanography 186SL067930012 University of California at San Diego 186SL067930013 La Jolla, California 186SL067930014Originator : unconfirmed 186SL067930015Original Data: unconfirmed 186SL067930016Instrmnt Type: unconfirmed 186SL067930017Digitzd Intvl: unconfirmed 186SL067930018Present Data : Hourly, daily, and monthly values obtained by: 186SL067930019 Hourly : unconfirmed 186SL067930020 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL067930021 centered on noon applied to the hourly data 186SL067930022 with respective periods of the 95, 50, and 5% 186SL067930023 amplitude points at 124.0, 60.2, and 40.2 hours 186SL067930024 Monthly: Simple average of all daily values; calculated if 186SL067930025 7 or fewer days are missing 186SL067930026Span of data : 01 Dec 1955 - 01 Apr 1972 186SL067930027Gaps > 1 mon : 03 Jul - 15 Aug 1956;16 Oct - 26 Nov 1959; 186SL067930028 01 Jan 1964 - 01 Jul 1965 186SL067930029Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 186SL067930030Units : millimeters Missing Data Flag :99999 186SL067930031Refernce Levl: All heights have been referred to the station tide 186SL067930032 staff zero which is linked to fixed bench marks 186SL067930033Comment : The daily and monthly means reveal no apparent 186SL067930034 changes in the reference level and agree with 186SL067930035 Kanton. This series is distinguished from 186SL067930036 Christmas-B because the data have not been linked 186SL067930037 to a common datum. 186SL067930038 186SL067930039 CI MISSING REPLACED GAPS QUESTIONABLE 186SL067930040YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL067930041---- --- -------------------- --------------- -------------------- 186SL0679300421955 8 none none none 186SL0679300431956 88 185-228 none none 186SL0679300441957 100 none none none 186SL0679300451958 100 none none none 186SL0679300461959 89 289-330 none none 186SL0679300471960 100 none none none 186SL0679300481961 100 none none none 186SL0679300491962 100 none none none 186SL0679300501963 100 none none none 186SL0679300511964 0 1-366 none none 186SL0679300521965 50 1-182 none none 186SL0679300531966 100 none none none 186SL0679300541967 100 none none none 186SL0679300551968 100 none none none 186SL0679300561969 100 none none none 186SL0679300571970 100 none none none 186SL0679300581971 100 none none none 186SL0679300591972 25 none none none 186SL067930060 186SL067930061 QUALITY ASSESSMENT POLICY 186SL067930062 186SL067930063 The quality assessment is mostly based on the residuals 186SL067930064 (observed data minus predicted tides) of the hourly data. This 186SL067930065 assessment also applies to the daily and monthly data since 186SL067930066 they were derived from the quality-controlled hourly data. 186SL067930067 186SL067930068 The following abbreviations are used in the assessment: 186SL067930069 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL067930070 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL067930071 research program; NODC - National Oceanographic Data Center; 186SL067930072 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL067930073 Gaps > 1 mon - missing data in a span greater than one month; 186SL067930074 Refernce - reference. 186SL067930075 186SL067930076 The following corrections are made to the hourly data 186SL067930077 prior to this assessment: 186SL067930078 1) Gaps or obviously wrong data points in a span less than 186SL067930079 25 hours are filled by the predicted tide method*. 186SL067930080 2) Timing errors of exact increments of an hour are corrected 186SL067930081 by shifting the data. 186SL067930082 3) Reference level shifts are only corrected after information 186SL067930083 from tide staff readings or comparative readings with a fixed 186SL067930084 bench mark are checked to verify that the shift was not a 186SL067930085 natural event. If comparative readings are missing or 186SL067930086 incomplete, comparisons of the data with nearby stations 186SL067930087 may warrant the adjustment of some obvious shifts. 186SL067930088 4) Data with unresolved datum shifts are not disseminated. 186SL067930089 However, if sufficient time spans of data are available before 186SL067930090 or after the year(s) with the unresolved shift(s), a subset of 186SL067930091 quality assured data is made available. Thus, the Span field 186SL067930092 in the Quality Assessment may not match the span of the 186SL067930093 distribution data set. As the questionable datum shifts are 186SL067930094 resolved, the data set will be updated. Although this policy 186SL067930095 adds some complexity, it allows more rapid dissemination of 186SL067930096 at least the quality assured years. 186SL067930097 186SL067930098 For each year, the following information is documented from 186SL067930099 the quality-controlled hourly data with dates given as the nth 186SL067930100 day of the year starting from 1 January: 186SL067930101 1) a Completeness Index (CI) based on the percentage of hours 186SL067930102 with available data, 186SL067930103 2) a list of gaps longer than a day, 186SL067930104 3) a summary of days with consecutive missing or obviously 186SL067930105 wrong data in a time span longer than 6 but less than 25 186SL067930106 hours that have been replaced, with hours in parentheses, and 186SL067930107 4) a summary of days with questionable fluctuations in the 186SL067930108 residual series. Fluctuations within the residuals are 186SL067930109 considered significant and are noted if they are greater than 186SL067930110 25 cm. This policy has changed slightly as of October 1992: 186SL067930111 only suspicious fluctuations due to obvious instrumentation 186SL067930112 problems are noted. Minor timing drifts are no longer 186SL067930113 included in the list of questionable days. 186SL067930114 186SL067930115 Note : If the predicted tides poorly model the observed heights 186SL067930116 due to the inability of the tidal analysis to completely resolv 186SL067930117 the non-linear shallow water effects, the residuals are not 186SL067930118 suitable for assessing the data quality. Instead, a subjective 186SL067930119 comment on the quality of the data is provided. 186SL067930120 186SL067930121 *The predicted tides are obtained with the use of a harmonic 186SL067930122 analysis program (Foreman, 1977) which is executed on a year 186SL067930123 of apparently good data for a given station. The Predicted 186SL067930124 Tide Method for filling gaps consists of statistically 186SL067930125 comparing the predicted tides to the observed data and 186SL067930126 shifting the predicted tides in time to correct for timing 186SL067930127 differences. Then the linear interpolation between hourly 186SL067930128 values at the end points of the gap in the residual series is 186SL067930129 added to the corresponding corrected predicted tide data to 186SL067930130 obtain interpolated values over the span of the gap. 186SL067930131 186SL067930132 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL067930133 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL067930134 186SL067930135 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL067930136 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL067930137 Victoria B.C. Pacific Marine Science Report 77-10. 186SL067930138 186SL06796 19551 999999999999999999999999999999999999999999999999 186SL06796 19552 9999999999999999999999999999999999999999 1128010 186SL06796 19561 1183000 1122000 1133000 1141000 1126000 1127000 186SL06796 19562 9999999999999999 1184000 1178000 1167000 1238000 186SL06796 19571 1210000 1209000 1171000 1172000 1192000 1138000 186SL06796 19572 1201000 1224000 1260000 1317000 1340000 1338000 186SL06796 19581 1276000 1216000 1159000 1146000 1147000 1158000 186SL06796 19582 1170000 1222000 1172000 1181000 1228000 1325000 186SL06796 19591 1277000 1256000 1211000 1181000 1167000 1138000 186SL06796 19592 1150000 1220000 12250009999999999999999 1197000 186SL06796 19601 1196000 1138000 1148000 1126000 1142000 1177000 186SL06796 19602 1204000 1140000 1188000 1213000 1193000 1229000 186SL06796 19611 1172000 1189000 1125000 1149000 1094000 1160000 186SL06796 19612 1206000 1199000 1204000 1213000 1200000 1199000 186SL06796 19621 1121000 1077000 1115000 1069000 1127000 1140000 186SL06796 19622 1163000 1217000 1199000 1183000 1154000 1227000 186SL06796 19631 1159000 1173000 1160000 1174000 1174000 1192000 186SL06796 19632 1275000 1277000 1292000 1302000 1323000 1255000 186SL06796 19641 999999999999999999999999999999999999999999999999 186SL06796 19642 999999999999999999999999999999999999999999999999 186SL06796 19651 999999999999999999999999999999999999999999999999 186SL06796 19652 1227010 1343000 1315000 1344000 1333000 1274000 186SL06796 19661 1175000 1159000 1124000 1118000 1124000 1146000 186SL06796 19662 1159000 1124000 1154000 1145000 1187000 1197000 186SL06796 19671 1062000 1056000 1085000 1153000 1155000 1149000 186SL06796 19672 1158000 1136000 1162000 1175000 1221000 1243000 186SL06796 19681 1148000 1162000 1155000 1131000 1165000 1156000 186SL06796 19682 1198000 1181000 1247000 1268000 1236000 1257000 186SL06796 19691 1263000 1226000 1208000 1120000 1127000 1099000 186SL06796 19692 1142000 1201000 1196000 1249000 1220000 1194000 186SL06796 19701 1194000 1114000 1122000 1079000 1097000 1107000 186SL06796 19702 1103000 1133000 1108000 1048000 1055000 1046000 186SL06796 19711 1084000 1109000 1069000 1122000 1111000 1083000 186SL06796 19712 1108000 1127000 1095000 1083000 1131000 1210000 186SL06796 19721 1159000 1186000 1180000999999999999999999999999 186SL06796 19722 999999999999999999999999999999999999999999999999