186SL0671150090001 003B 19850325 19931231 0026S 09017W 2 00000R 0000 MM 186SL0671250090001 Baltra-B Ecuador TOGA Sea Level Center 186SL067130001 186SL067130002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL067130003 by the 186SL067130004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL067130005 JOINT ARCHIVE FOR SEA LEVEL 186SL067130006 186SL067130007Station : Baltra-B,Galapagos Is. Latitude: 00 26.1S 186SL067130008Country : Ecuador Longitude: 090 17.1W 186SL067130009JASL # : 003B Time Meridian: 090W (GMT - 6 hr) 186SL067130010GLOSS # : 169 TOGA #: P082 NODC #: 50090001 186SL067130011Contributor : TOGA Sea Level Center 186SL067130012 1000 Pope Rd. MSB 317 186SL067130013 Honolulu, Hawaii 96822 186SL067130014Originator : Dept. of Oceanography 186SL067130015 University of Hawaii 186SL067130016 1000 Pope Rd. MSB 317 186SL067130017 Honolulu, Hawaii 96822 186SL067130018Original Data: digital 186SL067130019Instrmnt Type: 1. Leupold and Stevens Analog-to-Digital 186SL067130020 Recorder (ADR); 186SL067130021 2. Handar Encoder (ENC) 186SL067130022 Primary gauge: ADR: 1985-90, ENC: 1991- 186SL067130023Digitzd Intvl: 15 (ADR); 3 or 4 (ENC) minutes 186SL067130024Present Data : Hourly, daily, and monthly values obtained by: 186SL067130025 Hourly : (pre-1987) Nine-point triangular filter centered 186SL067130026 on the hour with respective periods of the 95, 50, 186SL067130027 and 5% amplitude point of the filter response at 186SL067130028 623.6, 177.0, and 103.7 minutes;(1987+) three-point 186SL067130029 Hanning filter centered on the hour 186SL067130030 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL067130031 centered on noon applied to the hourly data 186SL067130032 with respective periods of the 95, 50, and 5% 186SL067130033 amplitude points at 124.0, 60.2, and 40.2 hours 186SL067130034 Monthly: Simple average of all daily values; calculated if 186SL067130035 7 or fewer days are missing 186SL067130036Span of data : 25 Mar 1985 - 31 Dec 1993 186SL067130037Gaps > 1 mon : 05 Jan 1988 - 04 Feb 1988 186SL067130038Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 186SL067130039Units : millimeters Missing Data Flag :99999 186SL067130040Refernce Levl: All heights have been referred to the station tide 186SL067130041 staff zero which is linked to fixed bench marks 186SL067130042Comment : The daily and monthly means do not reveal any 186SL067130043 reference level changes or trends and agree well 186SL067130044 with Santa Cruz. This station is distinguished 186SL067130045 from station Baltra-A because the tide staffs 186SL067130046 have not been levelled to common bench marks. The 186SL067130047 hourly data contain significant timing errors in 186SL067130048 1988-1990 as noted below. Encoder data, as 186SL067130049 noted by * below, were used to fill some gaps. 186SL067130050 186SL067130051 CI MISSING REPLACED GAPS QUESTIONABLE 186SL067130052YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL067130053---- --- -------------------- --------------- -------------------- 186SL0671300541985 77 none none none 186SL0671300551986 90 280-308,330-338 none none 186SL0671300561987 100 none none none 186SL0671300571988 92 5-35,107-108 (14)061-(23)061 121-140,152-153 186SL067130058 (18)152-(23)152 186SL067130059 *(00)035-(20)048 186SL067130060 *(17)091-(11)107 186SL0671300611989 100 none (12)334-(23)334 152-161,168- 186SL067130062 *(18)001-(13)152 169,184-185,204,232- 186SL067130063 234,258-264,271-280, 186SL067130064 284-292,318-319,336- 186SL067130065 362 186SL0671300661990 100 none (02)151-(21)151 30-32,56-60,84-092, 186SL067130067 (12)213-(23)213 098-105,113-150, 186SL067130068 159-161 186SL0671300691991 100 none (10)202-(23)202 none 186SL067130070 *(00)274-(23)315 186SL0671300711992 99 317-322 (21)014-(20)015 none 186SL0671300721993 96 197-211 none none 186SL067130073 186SL067130074 QUALITY ASSESSMENT POLICY 186SL067130075 186SL067130076 The quality assessment is mostly based on the residuals 186SL067130077 (observed data minus predicted tides) of the hourly data. This 186SL067130078 assessment also applies to the daily and monthly data since 186SL067130079 they were derived from the quality-controlled hourly data. 186SL067130080 186SL067130081 The following abbreviations are used in the assessment: 186SL067130082 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL067130083 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL067130084 research program; NODC - National Oceanographic Data Center; 186SL067130085 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL067130086 Gaps > 1 mon - missing data in a span greater than one month; 186SL067130087 Refernce - reference. 186SL067130088 186SL067130089 The following corrections are made to the hourly data 186SL067130090 prior to this assessment: 186SL067130091 1) Gaps or obviously wrong data points in a span less than 186SL067130092 25 hours are filled by the predicted tide method*. 186SL067130093 2) Timing errors of exact increments of an hour are corrected 186SL067130094 by shifting the data. 186SL067130095 3) Reference level shifts are only corrected after information 186SL067130096 from tide staff readings or comparative readings with a fixed 186SL067130097 bench mark are checked to verify that the shift was not a 186SL067130098 natural event. If comparative readings are missing or 186SL067130099 incomplete, comparisons of the data with nearby stations 186SL067130100 may warrant the adjustment of some obvious shifts. 186SL067130101 4) Data with unresolved datum shifts are not disseminated. 186SL067130102 However, if sufficient time spans of data are available before 186SL067130103 or after the year(s) with the unresolved shift(s), a subset of 186SL067130104 quality assured data is made available. Thus, the Span field 186SL067130105 in the Quality Assessment may not match the span of the 186SL067130106 distribution data set. As the questionable datum shifts are 186SL067130107 resolved, the data set will be updated. Although this policy 186SL067130108 adds some complexity, it allows more rapid dissemination of 186SL067130109 at least the quality assured years. 186SL067130110 186SL067130111 For each year, the following information is documented from 186SL067130112 the quality-controlled hourly data with dates given as the nth 186SL067130113 day of the year starting from 1 January: 186SL067130114 1) a Completeness Index (CI) based on the percentage of hours 186SL067130115 with available data, 186SL067130116 2) a list of gaps longer than a day, 186SL067130117 3) a summary of days with consecutive missing or obviously 186SL067130118 wrong data in a time span longer than 6 but less than 25 186SL067130119 hours that have been replaced, with hours in parentheses, and 186SL067130120 4) a summary of days with questionable fluctuations in the 186SL067130121 residual series. Fluctuations within the residuals are 186SL067130122 considered significant and are noted if they are greater than 186SL067130123 25 cm. This policy has changed slightly as of October 1992: 186SL067130124 only suspicious fluctuations due to obvious instrumentation 186SL067130125 problems are noted. Minor timing drifts are no longer 186SL067130126 included in the list of questionable days. 186SL067130127 186SL067130128 Note : If the predicted tides poorly model the observed heights 186SL067130129 due to the inability of the tidal analysis to completely resolv 186SL067130130 the non-linear shallow water effects, the residuals are not 186SL067130131 suitable for assessing the data quality. Instead, a subjective 186SL067130132 comment on the quality of the data is provided. 186SL067130133 186SL067130134 *The predicted tides are obtained with the use of a harmonic 186SL067130135 analysis program (Foreman, 1977) which is executed on a year 186SL067130136 of apparently good data for a given station. The Predicted 186SL067130137 Tide Method for filling gaps consists of statistically 186SL067130138 comparing the predicted tides to the observed data and 186SL067130139 shifting the predicted tides in time to correct for timing 186SL067130140 differences. Then the linear interpolation between hourly 186SL067130141 values at the end points of the gap in the residual series is 186SL067130142 added to the corresponding corrected predicted tide data to 186SL067130143 obtain interpolated values over the span of the gap. 186SL067130144 186SL067130145 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL067130146 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL067130147 186SL067130148 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL067130149 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL067130150 Victoria B.C. Pacific Marine Science Report 77-10. 186SL067130151 186SL06716 19851 999999999999999999999999 1793000 1779000 1801000 186SL06716 19852 1770000 1755000 1771000 1755000 1754000 1746000 186SL06716 19861 1804000 1798000 1802000 1833000 1814000 1842000 186SL06716 19862 1828000 1792000 18130009999999999999999 1831040 186SL06716 19871 1963000 2025000 1904000 1950000 1923000 1868000 186SL06716 19872 1842000 1858000 1876000 1829000 1848000 1823000 186SL06716 19881 99999999 1795030 1795000 1751020 1748000 1723000 186SL06716 19882 1756000 1751000 1723000 1737000 1704000 1720000 186SL06716 19891 1738000 1810000 1831000 1849000 1833000 1821000 186SL06716 19892 1775000 1731000 1722000 1774000 1762000 1735000 186SL06716 19901 1871000 1876000 1854000 1874000 1823000 1813000 186SL06716 19902 1735000 1778000 1794000 1765000 1822000 1793000 186SL06716 19911 1911000 1948000 1865000 1814000 1912000 1904000 186SL06716 19912 1881000 1826000 1830000 1876000 1949000 1932000 186SL06716 19921 2048000 2053000 2061000 1994000 1933000 1852000 186SL06716 19922 1824000 1796000 1803000 1832000 1824060 1853000 186SL06716 19931 1887000 1921000 1926000 1990000 1974000 1938000 186SL06716 19932 99999999 1825000 1823000 1872000 1832000 1858000