186SL0830173039101 210B 19840101 19890128 3927N 03107W 2 00000R 0000 MM 186SL0830273039101 Flores-B,Azores Portugal Inst. Hidro. Marinha 186SL083030001 186SL083030002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL083030003 by the 186SL083030004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL083030005 JOINT ARCHIVE FOR SEA LEVEL 186SL083030006 186SL083030007Station : Flores-B,Azores Latitude: 39 27.2N 186SL083030008Country : Portugal Longitude: 031 07.2W 186SL083030009JASL # : 210B Time Meridian: 015W (GMT - 1 hr) 186SL083030010GLOSS # : 244 TOGA #: none NODC #: 73039101 186SL083030011Contributor : Instituto Hidrografico Marinha 186SL083030012 Rua das Trinas 186SL083030013 49-P-1296 Lisboa Codex 186SL083030014 Lisbon 186SL083030015 PORTUGAL 186SL083030016Originator : same 186SL083030017Original Data: analog 186SL083030018Instrmnt Type: Float and well, A.OTT 186SL083030019Digitzd Intvl: hourly 186SL083030020Present Data : Hourly, daily, and monthly values obtained by: 186SL083030021 Hourly : original data were hourly 186SL083030022 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL083030023 centered on noon applied to the hourly data 186SL083030024 with respective periods of the 95, 50, and 5% 186SL083030025 amplitude points at 124.0, 60.2, and 40.2 hours 186SL083030026 Monthly: Simple average of all daily values; calculated if 186SL083030027 7 or fewer days are missing 186SL083030028Span of data : 01 Jan 1984 - 28 Jan 1989 186SL083030029Gaps > 1 mon : 25 Dec 1986 - 07 Feb 1987; 01 - 31 Sep 1987; 186SL083030030 31 Oct 1988 - 05 Jan 1989 186SL083030031Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 186SL083030032Units : millimeters Missing Data Flag :99999 186SL083030033Refernce Levl: All heights have been referred to the station tide 186SL083030034 staff zero which is linked to fixed bench marks 186SL083030035Comment : The daily and monthly means reveal no 186SL083030036 apparent reference level changes or trends. 186SL083030037 186SL083030038 CI MISSING REPLACED GAPS QUESTIONABLE 186SL083030039YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL083030040---- --- -------------------- --------------- -------------------- 186SL0830300411984 100 none none 109-110,341,345 186SL0830300421985 99 200-205 none 5-9,17-23,35-42,82, 186SL083030043 92-99,228 186SL0830300441986 97 244-248,359-365 none 46,86-87,103,112- 186SL083030045 113,243,316-317 186SL0830300461987 79 1-38,244-274, none none 186SL083030047 294-303 186SL0830300481988 76 44-47,70-74, none none 186SL083030049 98-100,126-128, 186SL083030050 174-180,254-260, 186SL083030051 282-286,305-366 186SL0830300521989 6 1-5 none none 186SL083030053 186SL083030054 QUALITY ASSESSMENT POLICY 186SL083030055 186SL083030056 The quality assessment is mostly based on the residuals 186SL083030057 (observed data minus predicted tides) of the hourly data. This 186SL083030058 assessment also applies to the daily and monthly data since 186SL083030059 they were derived from the quality-controlled hourly data. 186SL083030060 186SL083030061 The following abbreviations are used in the assessment: 186SL083030062 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL083030063 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL083030064 research program; NODC - National Oceanographic Data Center; 186SL083030065 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL083030066 Gaps > 1 mon - missing data in a span greater than one month; 186SL083030067 Refernce - reference. 186SL083030068 186SL083030069 The following corrections are made to the hourly data 186SL083030070 prior to this assessment: 186SL083030071 1) Gaps or obviously wrong data points in a span less than 186SL083030072 25 hours are filled by the predicted tide method*. 186SL083030073 2) Timing errors of exact increments of an hour are corrected 186SL083030074 by shifting the data. 186SL083030075 3) Reference level shifts are only corrected after information 186SL083030076 from tide staff readings or comparative readings with a fixed 186SL083030077 bench mark are checked to verify that the shift was not a 186SL083030078 natural event. If comparative readings are missing or 186SL083030079 incomplete, comparisons of the data with nearby stations 186SL083030080 may warrant the adjustment of some obvious shifts. 186SL083030081 4) Data with unresolved datum shifts are not disseminated. 186SL083030082 However, if sufficient time spans of data are available before 186SL083030083 or after the year(s) with the unresolved shift(s), a subset of 186SL083030084 quality assured data is made available. Thus, the Span field 186SL083030085 in the Quality Assessment may not match the span of the 186SL083030086 distribution data set. As the questionable datum shifts are 186SL083030087 resolved, the data set will be updated. Although this policy 186SL083030088 adds some complexity, it allows more rapid dissemination of 186SL083030089 at least the quality assured years. 186SL083030090 186SL083030091 For each year, the following information is documented from 186SL083030092 the quality-controlled hourly data with dates given as the nth 186SL083030093 day of the year starting from 1 January: 186SL083030094 1) a Completeness Index (CI) based on the percentage of hours 186SL083030095 with available data, 186SL083030096 2) a list of gaps longer than a day, 186SL083030097 3) a summary of days with consecutive missing or obviously 186SL083030098 wrong data in a time span longer than 6 but less than 25 186SL083030099 hours that have been replaced, with hours in parentheses, and 186SL083030100 4) a summary of days with questionable fluctuations in the 186SL083030101 residual series. Fluctuations within the residuals are 186SL083030102 considered significant and are noted if they are greater than 186SL083030103 25 cm. This policy has changed slightly as of October 1992: 186SL083030104 only suspicious fluctuations due to obvious instrumentation 186SL083030105 problems are noted. Minor timing drifts are no longer 186SL083030106 included in the list of questionable days. 186SL083030107 186SL083030108 Note : If the predicted tides poorly model the observed heights 186SL083030109 due to the inability of the tidal analysis to completely resolv 186SL083030110 the non-linear shallow water effects, the residuals are not 186SL083030111 suitable for assessing the data quality. Instead, a subjective 186SL083030112 comment on the quality of the data is provided. 186SL083030113 186SL083030114 *The predicted tides are obtained with the use of a harmonic 186SL083030115 analysis program (Foreman, 1977) which is executed on a year 186SL083030116 of apparently good data for a given station. The Predicted 186SL083030117 Tide Method for filling gaps consists of statistically 186SL083030118 comparing the predicted tides to the observed data and 186SL083030119 shifting the predicted tides in time to correct for timing 186SL083030120 differences. Then the linear interpolation between hourly 186SL083030121 values at the end points of the gap in the residual series is 186SL083030122 added to the corresponding corrected predicted tide data to 186SL083030123 obtain interpolated values over the span of the gap. 186SL083030124 186SL083030125 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL083030126 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL083030127 186SL083030128 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL083030129 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL083030130 Victoria B.C. Pacific Marine Science Report 77-10. 186SL083030131 186SL08306 19841 900000 974000 1044000 1032000 898000 941000 186SL08306 19842 992000 962000 976000 978000 1055000 1023000 186SL08306 19851 1116000 1095000 1013000 1019000 929000 893000 186SL08306 19852 921050 1007000 1030000 1025000 1086000 950000 186SL08306 19861 883000 1029000 881000 930000 916000 928000 186SL08306 19862 944000 964000 942040 938000 960000 958070 186SL08306 19871 99999999 968070 971000 955000 988000 954000 186SL08306 19872 954000 10300009999999999999999 1002000 1132000 186SL08306 19881 957000 965030 927040 1021020 960020 905060 186SL08306 19882 888000 936000 984060 10370509999999999999999 186SL08306 19891 999999999999999999999999999999999999999999999999 186SL08306 19892 999999999999999999999999999999999999999999999999