186SL0888173005501 207D 19800429 19911231 3554N 00519W 2 00000R 0000 MM 186SL0888273005501 Ceuta-D Spain Inst. Espanol Ocean. 186SL088830001 186SL088830002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL088830003 by the 186SL088830004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL088830005 JOINT ARCHIVE FOR SEA LEVEL 186SL088830006 186SL088830007Station : Ceuta-D Latitude: 35 54.0N 186SL088830008Country : Spain Longitude: 005 19.0W 186SL088830009JASL # : 207D Time Meridian: GMT 186SL088830010GLOSS # : 249 TOGA #: none NODC #: 73005501 186SL088830011Contributor : Instituto Espanol de Oceanografia 186SL088830012 C/ Corazon de Maria, No. 8 - 1 186SL088830013 28002 Madrid 186SL088830014 SPAIN 186SL088830015Originator : same 186SL088830016Original Data: analog 186SL088830017Instrmnt Type: A.OTT, float and stilling well 186SL088830018Digitzd Intvl: one hour 186SL088830019Present Data : Hourly, daily, and monthly values obtained by: 186SL088830020 Hourly : direct digitization, no filter 186SL088830021 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL088830022 centered on noon applied to the hourly data 186SL088830023 with respective periods of the 95, 50, and 5% 186SL088830024 amplitude points at 124.0, 60.2, and 40.2 hours 186SL088830025 Monthly: Simple average of all daily values; calculated if 186SL088830026 7 or fewer days are missing 186SL088830027Span of data : 29 Apr 1980 - 31 Dec 1991 186SL088830028Gaps > 1 mon : 31 May 1988 - 03 Sep 1988;26 Jan 1990 - 05 May 1990 186SL088830029 11 May 1990 - 19 Sep 1990;30 Apr 1991 - 16 Jul 1991 186SL088830030Time Refernce: GMT (00-23 hours) Space-filler Flag :-9999 186SL088830031Units : millimeters Missing Data Flag :99999 186SL088830032Refernce Levl: The data have been linked to tide staff zero 186SL088830033 and fixed bench marks by the originators. 186SL088830034Comment : This series is separate from Ceuta-C because of 186SL088830035 a level shift during the data gap between 13 Apr 186SL088830036 1980 and 29 Apr 1980. Otherwise, no level shifts 186SL088830037 are apparent. The timing appears to be off by 186SL088830038 several minutes during most of 1982. 186SL088830039 186SL088830040 CI MISSING REPLACED GAPS QUESTIONABLE 186SL088830041YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL088830042---- --- -------------------- --------------- -------------------- 186SL0888300431980 64 294-305 none none 186SL0888300441981 100 none none none 186SL0888300451982 92 291-298,308-318, (00)363-(10)363 none 186SL088830046 344-355 186SL0888300471983 100 none none none 186SL0888300481984 100 none none none 186SL0888300491985 100 none none none 186SL0888300501986 100 none (01)177-(23)177 none 186SL0888300511987 100 none none none 186SL0888300521988 74 152-247 none none 186SL0888300531989 100 none none none 186SL0888300541990 38 26-125,131-262 none 25-26 186SL0888300551991 78 110-114,120-197 none 79-84 186SL088830056 186SL088830057 QUALITY ASSESSMENT POLICY 186SL088830058 186SL088830059 The quality assessment is mostly based on the residuals 186SL088830060 (observed data minus predicted tides) of the hourly data. This 186SL088830061 assessment also applies to the daily and monthly data since 186SL088830062 they were derived from the quality-controlled hourly data. 186SL088830063 186SL088830064 The following abbreviations are used in the assessment: 186SL088830065 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL088830066 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL088830067 research program; NODC - National Oceanographic Data Center; 186SL088830068 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL088830069 Gaps > 1 mon - missing data in a span greater than one month; 186SL088830070 Refernce - reference. 186SL088830071 186SL088830072 The following corrections are made to the hourly data 186SL088830073 prior to this assessment: 186SL088830074 1) Gaps or obviously wrong data points in a span less than 186SL088830075 25 hours are filled by the predicted tide method*. 186SL088830076 2) Timing errors of exact increments of an hour are corrected 186SL088830077 by shifting the data. 186SL088830078 3) Reference level shifts are only corrected after information 186SL088830079 from tide staff readings or comparative readings with a fixed 186SL088830080 bench mark are checked to verify that the shift was not a 186SL088830081 natural event. If comparative readings are missing or 186SL088830082 incomplete, comparisons of the data with nearby stations 186SL088830083 may warrant the adjustment of some obvious shifts. 186SL088830084 4) Data with unresolved datum shifts are not disseminated. 186SL088830085 However, if sufficient time spans of data are available before 186SL088830086 or after the year(s) with the unresolved shift(s), a subset of 186SL088830087 quality assured data is made available. Thus, the Span field 186SL088830088 in the Quality Assessment may not match the span of the 186SL088830089 distribution data set. As the questionable datum shifts are 186SL088830090 resolved, the data set will be updated. Although this policy 186SL088830091 adds some complexity, it allows more rapid dissemination of 186SL088830092 at least the quality assured years. 186SL088830093 186SL088830094 For each year, the following information is documented from 186SL088830095 the quality-controlled hourly data with dates given as the nth 186SL088830096 day of the year starting from 1 January: 186SL088830097 1) a Completeness Index (CI) based on the percentage of hours 186SL088830098 with available data, 186SL088830099 2) a list of gaps longer than a day, 186SL088830100 3) a summary of days with consecutive missing or obviously 186SL088830101 wrong data in a time span longer than 6 but less than 25 186SL088830102 hours that have been replaced, with hours in parentheses, and 186SL088830103 4) a summary of days with questionable fluctuations in the 186SL088830104 residual series. Fluctuations within the residuals are 186SL088830105 considered significant and are noted if they are greater than 186SL088830106 25 cm. This policy has changed slightly as of October 1992: 186SL088830107 only suspicious fluctuations due to obvious instrumentation 186SL088830108 problems are noted. Minor timing drifts are no longer 186SL088830109 included in the list of questionable days. 186SL088830110 186SL088830111 Note : If the predicted tides poorly model the observed heights 186SL088830112 due to the inability of the tidal analysis to completely resolv 186SL088830113 the non-linear shallow water effects, the residuals are not 186SL088830114 suitable for assessing the data quality. Instead, a subjective 186SL088830115 comment on the quality of the data is provided. 186SL088830116 186SL088830117 *The predicted tides are obtained with the use of a harmonic 186SL088830118 analysis program (Foreman, 1977) which is executed on a year 186SL088830119 of apparently good data for a given station. The Predicted 186SL088830120 Tide Method for filling gaps consists of statistically 186SL088830121 comparing the predicted tides to the observed data and 186SL088830122 shifting the predicted tides in time to correct for timing 186SL088830123 differences. Then the linear interpolation between hourly 186SL088830124 values at the end points of the gap in the residual series is 186SL088830125 added to the corresponding corrected predicted tide data to 186SL088830126 obtain interpolated values over the span of the gap. 186SL088830127 186SL088830128 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL088830129 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL088830130 186SL088830131 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL088830132 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL088830133 Victoria B.C. Pacific Marine Science Report 77-10. 186SL088830134 186SL08886 19801 99999999999999999999999999999999 1006000 988000 186SL08886 19802 1008000 1010000 101700099999999 1034000 894000 186SL08886 19811 848000 900000 953000 951000 925000 959000 186SL08886 19812 928000 1019000 1017000 1041000 992000 1021000 186SL08886 19821 1019000 957000 922000 1026000 945000 972000 186SL08886 19822 990000 996000 1044000 10590709999999999999999 186SL08886 19831 811000 962000 906000 950000 995000 991000 186SL08886 19832 1030000 1005000 1025000 1029000 1160000 1035000 186SL08886 19841 909000 935000 1021000 1024000 1036000 973000 186SL08886 19842 981000 1007000 1049000 950000 992000 936000 186SL08886 19851 1012000 936000 918000 973000 1018000 1001000 186SL08886 19852 987000 981000 997000 1014000 1079000 981000 186SL08886 19861 897000 1019000 917000 965000 946000 1010000 186SL08886 19862 1031000 1013000 1016000 1034000 953000 900000 186SL08886 19871 951000 961000 979000 960000 982000 955000 186SL08886 19872 1037000 1044000 1035000 1077000 1052000 1087000 186SL08886 19881 947000 938000 934000 964000 98701099999999 186SL08886 19882 9999999999999999 994020 1042000 1109000 953000 186SL08886 19891 912000 867000 902000 930000 948000 961000 186SL08886 19892 965000 995000 1009000 1034000 1137000 1174000 186SL08886 19901 9420609999999999999999999999999999999999999999 186SL08886 19902 999999999999999999999999 993000 958000 932000 186SL08886 19911 864000 904000 934000 8610509999999999999999 186SL08886 19912 99999999 922000 941000 970000 897000 881000