186SL0881172018301 205D 19870101 19911231 2857N 01334W 2 00000R 0000 MM 186SL0881272018301 Arrecife-D Spain Inst. Espanol Ocean. 186SL088130001 186SL088130002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL088130003 by the 186SL088130004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL088130005 JOINT ARCHIVE FOR SEA LEVEL 186SL088130006 186SL088130007Station : Arrecife-D Latitude: 28 57.0N 186SL088130008Country : Spain Longitude: 013 34.0W 186SL088130009JASL # : 205D Time Meridian: GMT 186SL088130010GLOSS # : none TOGA #: none NODC #: 72018301 186SL088130011Contributor : Instituto Espanol de Oceanografia 186SL088130012 C/ Corazon de Maria, No. 8 - 1 186SL088130013 28002 Madrid 186SL088130014 SPAIN 186SL088130015Originator : same 186SL088130016Original Data: analog 186SL088130017Instrmnt Type: A.OTT, float and stilling well 186SL088130018Digitzd Intvl: one hour 186SL088130019Present Data : Hourly, daily, and monthly values obtained by: 186SL088130020 Hourly : direct digitization, no filter 186SL088130021 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL088130022 centered on noon applied to the hourly data 186SL088130023 with respective periods of the 95, 50, and 5% 186SL088130024 amplitude points at 124.0, 60.2, and 40.2 hours 186SL088130025 Monthly: Simple average of all daily values; calculated if 186SL088130026 7 or fewer days are missing 186SL088130027Span of data : 01 Jan 1987 - 31 Dec 1991 186SL088130028Gaps > 1 mon : 01 Mar 1991 - 17 Apr 1991 186SL088130029Time Refernce: GMT (00-23 hours) Space-filler Flag :-9999 186SL088130030Units : millimeters Missing Data Flag :99999 186SL088130031Refernce Levl: The data have been linked to tide staff zero 186SL088130032 and fixed bench marks by the originators. 186SL088130033Comment : This series is separate from Arrecife-C because 186SL088130034 of a level shift 27 Dec 1986. Otherwise, no 186SL088130035 level shifts are apparent. 186SL088130036 186SL088130037 CI MISSING REPLACED GAPS QUESTIONABLE 186SL088130038YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL088130039---- --- -------------------- --------------- -------------------- 186SL0881300401987 100 none (17)181-(23)181 16-19,85-92,108-110, 186SL088130041 (18)191-(01)192 243-244 186SL088130042 (04)245-(13)245 186SL088130043 (15)252-(01)253 186SL088130044 (00)278-(13)278 186SL088130045 (01)296-(13)296 186SL0881300461988 98 13-22 none 153-162,255-260 186SL0881300471989 90 1-25,352-365 none 37-52,60-62,71-73, 186SL088130048 94-99 186SL0881300491990 94 1-5,34-40,212-224 none 142-147,340-346,365 186SL0881300501991 70 1-6,51-58,60-107, (06)162-(23)162 14-16,45-49 186SL088130051 227-235,259-264,282- (00)361-(09)361 186SL088130052 302,308-314,331-341, 186SL088130053 345-350,356-360 186SL088130054 186SL088130055 QUALITY ASSESSMENT POLICY 186SL088130056 186SL088130057 The quality assessment is mostly based on the residuals 186SL088130058 (observed data minus predicted tides) of the hourly data. This 186SL088130059 assessment also applies to the daily and monthly data since 186SL088130060 they were derived from the quality-controlled hourly data. 186SL088130061 186SL088130062 The following abbreviations are used in the assessment: 186SL088130063 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL088130064 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL088130065 research program; NODC - National Oceanographic Data Center; 186SL088130066 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL088130067 Gaps > 1 mon - missing data in a span greater than one month; 186SL088130068 Refernce - reference. 186SL088130069 186SL088130070 The following corrections are made to the hourly data 186SL088130071 prior to this assessment: 186SL088130072 1) Gaps or obviously wrong data points in a span less than 186SL088130073 25 hours are filled by the predicted tide method*. 186SL088130074 2) Timing errors of exact increments of an hour are corrected 186SL088130075 by shifting the data. 186SL088130076 3) Reference level shifts are only corrected after information 186SL088130077 from tide staff readings or comparative readings with a fixed 186SL088130078 bench mark are checked to verify that the shift was not a 186SL088130079 natural event. If comparative readings are missing or 186SL088130080 incomplete, comparisons of the data with nearby stations 186SL088130081 may warrant the adjustment of some obvious shifts. 186SL088130082 4) Data with unresolved datum shifts are not disseminated. 186SL088130083 However, if sufficient time spans of data are available before 186SL088130084 or after the year(s) with the unresolved shift(s), a subset of 186SL088130085 quality assured data is made available. Thus, the Span field 186SL088130086 in the Quality Assessment may not match the span of the 186SL088130087 distribution data set. As the questionable datum shifts are 186SL088130088 resolved, the data set will be updated. Although this policy 186SL088130089 adds some complexity, it allows more rapid dissemination of 186SL088130090 at least the quality assured years. 186SL088130091 186SL088130092 For each year, the following information is documented from 186SL088130093 the quality-controlled hourly data with dates given as the nth 186SL088130094 day of the year starting from 1 January: 186SL088130095 1) a Completeness Index (CI) based on the percentage of hours 186SL088130096 with available data, 186SL088130097 2) a list of gaps longer than a day, 186SL088130098 3) a summary of days with consecutive missing or obviously 186SL088130099 wrong data in a time span longer than 6 but less than 25 186SL088130100 hours that have been replaced, with hours in parentheses, and 186SL088130101 4) a summary of days with questionable fluctuations in the 186SL088130102 residual series. Fluctuations within the residuals are 186SL088130103 considered significant and are noted if they are greater than 186SL088130104 25 cm. This policy has changed slightly as of October 1992: 186SL088130105 only suspicious fluctuations due to obvious instrumentation 186SL088130106 problems are noted. Minor timing drifts are no longer 186SL088130107 included in the list of questionable days. 186SL088130108 186SL088130109 Note : If the predicted tides poorly model the observed heights 186SL088130110 due to the inability of the tidal analysis to completely resolv 186SL088130111 the non-linear shallow water effects, the residuals are not 186SL088130112 suitable for assessing the data quality. Instead, a subjective 186SL088130113 comment on the quality of the data is provided. 186SL088130114 186SL088130115 *The predicted tides are obtained with the use of a harmonic 186SL088130116 analysis program (Foreman, 1977) which is executed on a year 186SL088130117 of apparently good data for a given station. The Predicted 186SL088130118 Tide Method for filling gaps consists of statistically 186SL088130119 comparing the predicted tides to the observed data and 186SL088130120 shifting the predicted tides in time to correct for timing 186SL088130121 differences. Then the linear interpolation between hourly 186SL088130122 values at the end points of the gap in the residual series is 186SL088130123 added to the corresponding corrected predicted tide data to 186SL088130124 obtain interpolated values over the span of the gap. 186SL088130125 186SL088130126 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL088130127 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL088130128 186SL088130129 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL088130130 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL088130131 Victoria B.C. Pacific Marine Science Report 77-10. 186SL088130132 186SL08816 19871 1642000 1574000 1643000 1627000 1639000 1636000 186SL08816 19872 1685000 1692000 1696000 1715000 1688000 1664000 186SL08816 19881 99999999 1727000 1726000 1795000 1790000 1831000 186SL08816 19882 1846000 1878000 1850000 1838000 1859000 1781010 186SL08816 19891 99999999 1763000 1826000 1825000 1855000 1877000 186SL08816 19892 1886000 1938000 1918000 1910000 193900099999999 186SL08816 19901 1785040 1727060 1812000 1853000 1839000 1848000 186SL08816 19902 191901099999999 1892000 1912000 1888000 1886010 186SL08816 19911 1769050 17660709999999999999999 1774000 1814000 186SL08816 19912 182700099999999 1894040999999999999999999999999