186SL0804130143301 063A 19840828 19931209 0334S 14338E 2 00000R 0000 MM 186SL0804230143301 Wewak Papua New Guinea CSIRO 186SL080430001 186SL080430002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL080430003 by the 186SL080430004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL080430005 JOINT ARCHIVE FOR SEA LEVEL 186SL080430006 186SL080430007Station : Wewak Latitude: 03 34.2S 186SL080430008Country : Papua New Guinea Longitude: 143 38.0E 186SL080430009JASL # : 063A Time Meridian: 150E (GMT + 10 hr) 186SL080430010GLOSS # : none TOGA #: P020 NODC #: 30143301 186SL080430011Contributor : CSIRO 186SL080430012 Division of Oceanography 186SL080430013 GPO Box 1538 186SL080430014 Hobart, Tasmania 7001 186SL080430015Originator : same 186SL080430016Original Data: digital 186SL080430017Instrmnt Type: Leupold Stevens analog-to-digital recorder 186SL080430018Digitzd Intvl: 15 minutes 186SL080430019Present Data : Hourly, daily, and monthly values obtained by: 186SL080430020 Hourly : simple Gaussian filter 186SL080430021 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL080430022 centered on noon applied to the hourly data 186SL080430023 with respective periods of the 95, 50, and 5% 186SL080430024 amplitude points at 124.0, 60.2, and 40.2 hours 186SL080430025 Monthly: Simple average of all daily values; calculated if 186SL080430026 7 or fewer days are missing 186SL080430027Span of data : 28 Aug 1984 - 09 Dec 1993 186SL080430028Gaps > 1 mon : 26 Feb - 1 Apr 1987; 08 Jun - 06 Dec 1990 186SL080430029 09 May 1993 - 30 Jun 1993 186SL080430030Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 186SL080430031Units : millimeters Missing Data Flag :99999 186SL080430032Refernce Levl: All heights have been referred to the station tide 186SL080430033 staff zero which is linked to fixed bench marks 186SL080430034Comment : The daily and monthly means reveal no 186SL080430035 apparent reference level changes or trends. The 186SL080430036 gauge is located in a region known to be tectoni- 186SL080430037 cally unstable. 186SL080430038 186SL080430039 CI MISSING REPLACED GAPS QUESTIONABLE 186SL080430040YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL080430041---- --- -------------------- --------------- -------------------- 186SL0804300421984 34 none none none 186SL0804300431985 100 none none none 186SL0804300441986 100 none none none 186SL0804300451987 91 57-91 none 54-56 186SL0804300461988 99 352-355 none none 186SL0804300471989 96 131-132,167-168, none none 186SL080430048 305-318 186SL0804300491990 46 32-33,115-130, none none 186SL080430050 159-340 186SL0804300511991 96 117-128,204-207, none none 186SL080430052 296-298 186SL0804300531992 96 89-91,220-233, none none 186SL080430054 260-262 186SL0804300551993 72 102-127,129-181, none 237-245 186SL080430056 274-277,301-304 186SL080430057 186SL080430058 QUALITY ASSESSMENT POLICY 186SL080430059 186SL080430060 The quality assessment is mostly based on the residuals 186SL080430061 (observed data minus predicted tides) of the hourly data. This 186SL080430062 assessment also applies to the daily and monthly data since 186SL080430063 they were derived from the quality-controlled hourly data. 186SL080430064 186SL080430065 The following abbreviations are used in the assessment: 186SL080430066 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL080430067 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL080430068 research program; NODC - National Oceanographic Data Center; 186SL080430069 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL080430070 Gaps > 1 mon - missing data in a span greater than one month; 186SL080430071 Refernce - reference. 186SL080430072 186SL080430073 The following corrections are made to the hourly data 186SL080430074 prior to this assessment: 186SL080430075 1) Gaps or obviously wrong data points in a span less than 186SL080430076 25 hours are filled by the predicted tide method*. 186SL080430077 2) Timing errors of exact increments of an hour are corrected 186SL080430078 by shifting the data. 186SL080430079 3) Reference level shifts are only corrected after information 186SL080430080 from tide staff readings or comparative readings with a fixed 186SL080430081 bench mark are checked to verify that the shift was not a 186SL080430082 natural event. If comparative readings are missing or 186SL080430083 incomplete, comparisons of the data with nearby stations 186SL080430084 may warrant the adjustment of some obvious shifts. 186SL080430085 4) Data with unresolved datum shifts are not disseminated. 186SL080430086 However, if sufficient time spans of data are available before 186SL080430087 or after the year(s) with the unresolved shift(s), a subset of 186SL080430088 quality assured data is made available. Thus, the Span field 186SL080430089 in the Quality Assessment may not match the span of the 186SL080430090 distribution data set. As the questionable datum shifts are 186SL080430091 resolved, the data set will be updated. Although this policy 186SL080430092 adds some complexity, it allows more rapid dissemination of 186SL080430093 at least the quality assured years. 186SL080430094 186SL080430095 For each year, the following information is documented from 186SL080430096 the quality-controlled hourly data with dates given as the nth 186SL080430097 day of the year starting from 1 January: 186SL080430098 1) a Completeness Index (CI) based on the percentage of hours 186SL080430099 with available data, 186SL080430100 2) a list of gaps longer than a day, 186SL080430101 3) a summary of days with consecutive missing or obviously 186SL080430102 wrong data in a time span longer than 6 but less than 25 186SL080430103 hours that have been replaced, with hours in parentheses, and 186SL080430104 4) a summary of days with questionable fluctuations in the 186SL080430105 residual series. Fluctuations within the residuals are 186SL080430106 considered significant and are noted if they are greater than 186SL080430107 25 cm. This policy has changed slightly as of October 1992: 186SL080430108 only suspicious fluctuations due to obvious instrumentation 186SL080430109 problems are noted. Minor timing drifts are no longer 186SL080430110 included in the list of questionable days. 186SL080430111 186SL080430112 Note : If the predicted tides poorly model the observed heights 186SL080430113 due to the inability of the tidal analysis to completely resolv 186SL080430114 the non-linear shallow water effects, the residuals are not 186SL080430115 suitable for assessing the data quality. Instead, a subjective 186SL080430116 comment on the quality of the data is provided. 186SL080430117 186SL080430118 *The predicted tides are obtained with the use of a harmonic 186SL080430119 analysis program (Foreman, 1977) which is executed on a year 186SL080430120 of apparently good data for a given station. The Predicted 186SL080430121 Tide Method for filling gaps consists of statistically 186SL080430122 comparing the predicted tides to the observed data and 186SL080430123 shifting the predicted tides in time to correct for timing 186SL080430124 differences. Then the linear interpolation between hourly 186SL080430125 values at the end points of the gap in the residual series is 186SL080430126 added to the corresponding corrected predicted tide data to 186SL080430127 obtain interpolated values over the span of the gap. 186SL080430128 186SL080430129 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL080430130 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL080430131 186SL080430132 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL080430133 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL080430134 Victoria B.C. Pacific Marine Science Report 77-10. 186SL080430135 186SL08046 19841 999999999999999999999999999999999999999999999999 186SL08046 19842 9999999999999999 1003000 1039000 1003000 982000 186SL08046 19851 949000 1051000 976000 1102000 1117000 1112000 186SL08046 19852 1096000 1071000 1086000 1119000 1033000 975000 186SL08046 19861 992000 984000 1102000 1069000 1106000 1090000 186SL08046 19862 1073000 1074000 1028000 1023000 1029000 929000 186SL08046 19871 880000 85903099999999 963010 991000 981000 186SL08046 19872 964000 962000 941000 967000 1012000 953000 186SL08046 19881 932000 929000 1071000 1115000 1155000 1136000 186SL08046 19882 1149000 1161000 1176000 1157000 1151000 1091040 186SL08046 19891 1099000 1132000 1186000 1194000 1182020 1148020 186SL08046 19892 1120000 1115000 1118000 112400099999999 1017000 186SL08046 19901 1033000 974020 945000 10210609999999999999999 186SL08046 19902 9999999999999999999999999999999999999999 943050 186SL08046 19911 946000 972000 1013000 1082040 1068070 1043000 186SL08046 19912 1030030 1036000 1025000 1022020 998000 939000 186SL08046 19921 943000 956000 963020 1045000 1060000 1043000 186SL08046 19922 107600099999999 1089030 1159000 1129000 1034000 186SL08046 19931 1003000 1001000 1019000999999999999999999999999 186SL08046 19932 1092000 1076000 1080000 1114070 110800099999999