186SL0902112125101 341A 19840101 19911231 2508N 12144E 2 00000R 0000 MM 186SL0902212125101 Keelung Rep. of China Central Weather Bureau 186SL090230001 186SL090230002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL090230003 by the 186SL090230004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL090230005 JOINT ARCHIVE FOR SEA LEVEL 186SL090230006 186SL090230007Station : Keelung Latitude: 25 08.0N 186SL090230008Country : Republic of China Longitude: 121 44.0E 186SL090230009JASL # : 341A Time Meridian: 120E (GMT + 8 hr) 186SL090230010GLOSS # : none TOGA #: none NODC #: 12125101 186SL090230011Contributor : Central Weather Bureau 186SL090230012 64 Kung Yuan, Taipei, Taiwan 186SL090230013 REPUBLIC OF CHINA 10039 186SL090230014Originator : same 186SL090230015Original Data: unconfirmed 186SL090230016Instrmnt Type: unconfirmed 186SL090230017Digitzd Intvl: unconfirmed 186SL090230018Present Data : Hourly, daily, and monthly values obtained by: 186SL090230019 Hourly : unconfirmed 186SL090230020 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL090230021 centered on noon applied to the hourly data 186SL090230022 with respective periods of the 95, 50, and 5% 186SL090230023 amplitude points at 124.0, 60.2, and 40.2 hours 186SL090230024 Monthly: Simple average of all daily values; calculated if 186SL090230025 7 or fewer days are missing 186SL090230026Span of data : 01 Jan 1984 - 31 Dec 1991 186SL090230027Gaps > 1 mon : none 186SL090230028Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 186SL090230029Units : millimeters Missing Data Flag :99999 186SL090230030Refernce Levl: The sea level heights are referred to the Tidal 186SL090230031 Datum and fixed bench marks. Information is 186SL090230032 available upon request from the contributors. 186SL090230033Comment : The data set is of excellent quality. The monthly 186SL090230034 means agree fairly well with Kaohsiung. Minor 186SL090230035 timing drifts are suspected in the hourly data. 186SL090230036 186SL090230037 CI MISSING REPLACED GAPS QUESTIONABLE 186SL090230038YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL090230039---- --- -------------------- --------------- -------------------- 186SL0902300401984 100 none none none 186SL0902300411985 100 none none none 186SL0902300421986 100 none none none 186SL0902300431987 100 none none 211 186SL0902300441988 100 none none none 186SL0902300451989 100 none none none 186SL0902300461990 100 none none 231-232 186SL0902300471991 99 365 none none 186SL090230048 186SL090230049 QUALITY ASSESSMENT POLICY 186SL090230050 186SL090230051 The quality assessment is mostly based on the residuals 186SL090230052 (observed data minus predicted tides) of the hourly data. This 186SL090230053 assessment also applies to the daily and monthly data since 186SL090230054 they were derived from the quality-controlled hourly data. 186SL090230055 186SL090230056 The following abbreviations are used in the assessment: 186SL090230057 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL090230058 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL090230059 research program; NODC - National Oceanographic Data Center; 186SL090230060 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL090230061 Gaps > 1 mon - missing data in a span greater than one month; 186SL090230062 Refernce - reference. 186SL090230063 186SL090230064 The following corrections are made to the hourly data 186SL090230065 prior to this assessment: 186SL090230066 1) Gaps or obviously wrong data points in a span less than 186SL090230067 25 hours are filled by the predicted tide method*. 186SL090230068 2) Timing errors of exact increments of an hour are corrected 186SL090230069 by shifting the data. 186SL090230070 3) Reference level shifts are only corrected after information 186SL090230071 from tide staff readings or comparative readings with a fixed 186SL090230072 bench mark are checked to verify that the shift was not a 186SL090230073 natural event. If comparative readings are missing or 186SL090230074 incomplete, comparisons of the data with nearby stations 186SL090230075 may warrant the adjustment of some obvious shifts. 186SL090230076 4) Data with unresolved datum shifts are not disseminated. 186SL090230077 However, if sufficient time spans of data are available before 186SL090230078 or after the year(s) with the unresolved shift(s), a subset of 186SL090230079 quality assured data is made available. Thus, the Span field 186SL090230080 in the Quality Assessment may not match the span of the 186SL090230081 distribution data set. As the questionable datum shifts are 186SL090230082 resolved, the data set will be updated. Although this policy 186SL090230083 adds some complexity, it allows more rapid dissemination of 186SL090230084 at least the quality assured years. 186SL090230085 186SL090230086 For each year, the following information is documented from 186SL090230087 the quality-controlled hourly data with dates given as the nth 186SL090230088 day of the year starting from 1 January: 186SL090230089 1) a Completeness Index (CI) based on the percentage of hours 186SL090230090 with available data, 186SL090230091 2) a list of gaps longer than a day, 186SL090230092 3) a summary of days with consecutive missing or obviously 186SL090230093 wrong data in a time span longer than 6 but less than 25 186SL090230094 hours that have been replaced, with hours in parentheses, and 186SL090230095 4) a summary of days with questionable fluctuations in the 186SL090230096 residual series. Fluctuations within the residuals are 186SL090230097 considered significant and are noted if they are greater than 186SL090230098 25 cm. This policy has changed slightly as of October 1992: 186SL090230099 only suspicious fluctuations due to obvious instrumentation 186SL090230100 problems are noted. Minor timing drifts are no longer 186SL090230101 included in the list of questionable days. 186SL090230102 186SL090230103 Note : If the predicted tides poorly model the observed heights 186SL090230104 due to the inability of the tidal analysis to completely resolv 186SL090230105 the non-linear shallow water effects, the residuals are not 186SL090230106 suitable for assessing the data quality. Instead, a subjective 186SL090230107 comment on the quality of the data is provided. 186SL090230108 186SL090230109 *The predicted tides are obtained with the use of a harmonic 186SL090230110 analysis program (Foreman, 1977) which is executed on a year 186SL090230111 of apparently good data for a given station. The Predicted 186SL090230112 Tide Method for filling gaps consists of statistically 186SL090230113 comparing the predicted tides to the observed data and 186SL090230114 shifting the predicted tides in time to correct for timing 186SL090230115 differences. Then the linear interpolation between hourly 186SL090230116 values at the end points of the gap in the residual series is 186SL090230117 added to the corresponding corrected predicted tide data to 186SL090230118 obtain interpolated values over the span of the gap. 186SL090230119 186SL090230120 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL090230121 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL090230122 186SL090230123 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL090230124 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL090230125 Victoria B.C. Pacific Marine Science Report 77-10. 186SL090230126 186SL09026 19841 775000 777000 813000 890000 961000 1078000 186SL09026 19842 1046000 1096000 996000 967000 909000 786000 186SL09026 19851 681000 794000 775000 806000 928000 1047000 186SL09026 19852 1051000 1104000 996000 906000 850000 748000 186SL09026 19861 703000 715000 843000 853000 895000 994000 186SL09026 19862 1055000 1076000 990000 871000 806000 786000 186SL09026 19871 756000 730000 797000 829000 906000 983000 186SL09026 19872 1037000 1070000 987000 927000 853000 787000 186SL09026 19881 779000 750000 851000 873000 982000 1048000 186SL09026 19882 1081000 1089000 1038000 951000 769000 715000 186SL09026 19891 763000 762000 805000 901000 952000 1013000 186SL09026 19892 1087000 1158000 1043000 893000 858000 824000 186SL09026 19901 812000 786000 791000 882000 909000 1018000 186SL09026 19902 1057000 1168000 1078000 945000 894000 744000 186SL09026 19911 763000 790000 868000 896000 936000 1031000 186SL09026 19912 1076000 1178000 1110000 1016000 828000 850010