186SL0726172116101 319A 19750501 19880731 2601N 11122W 2 00000R 0000 MM 186SL0726272116101 Loreto Mexico CICESE 186SL072630001 186SL072630002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL072630003 by the 186SL072630004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL072630005 JOINT ARCHIVE FOR SEA LEVEL 186SL072630006 186SL072630007Station : Loreto Latitude: 26 01.0N 186SL072630008Country : Mexico Longitude: 111 22.0W 186SL072630009JASL # : 319A Time Meridian: 105W (GMT - 7 hr) 186SL072630010GLOSS # : none TOGA #: none NODC #: 72116101 186SL072630011Contributor : Centro de Investigacion Cientifica 186SL072630012 y de Educacion Superior de Ensenada (CICESE) 186SL072630013 Av. Espinoza No. 843 186SL072630014 APDO. Postal 2732 186SL072630015 Ensenada, Baja California, Mexico 186SL072630016Originator : same 186SL072630017Original Data: digital 186SL072630018Instrmnt Type: Leupold and Stevens Mod. 7001, float-type gauge 186SL072630019Digitzd Intvl: 30 minutes 186SL072630020Present Data : Hourly, daily, and monthly values obtained by: 186SL072630021 Hourly : Running mean A2,A2,A3 (Godin,1972) 186SL072630022 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL072630023 centered on noon applied to the hourly data 186SL072630024 with respective periods of the 95, 50, and 5% 186SL072630025 amplitude points at 124.0, 60.2, and 40.2 hours 186SL072630026 Monthly: Simple average of all daily values; calculated if 186SL072630027 7 or fewer days are missing 186SL072630028Span of data : 01 May 1975 - 31 Jul 1988 186SL072630029Gaps > 1 mon : 01 Sep 1976 - 25 Apr 1977;16 Aug 1977 - 20 Sep 1977 186SL072630030 22 Apr 1981 - 07 Aug 1981;02 May 1983 - 10 Jun 1983 186SL072630031 15 Dec 1983 - 01 Jan 1985;27 Nov 1985 - 21 Jan 1986 186SL072630032 11 Oct 1986 - 07 Dec 1986;22 Feb 1987 - 10 Jun 1987 186SL072630033 03 Aug 1987 - 20 Oct 1987 186SL072630034Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 186SL072630035Units : millimeters Missing Data Flag :99999 186SL072630036Refernce Levl: The sea level heights are referred to the tide 186SL072630037 staff zero which is linked to fixed bench marks. 186SL072630038Comment : The daily and monthly values do not reveal any 186SL072630039 obvious reference level shifts or trends and agree 186SL072630040 reasonably well with the nearest station, 186SL072630041 Cabo San Lucas, Baja California. 186SL072630042 186SL072630043 CI MISSING REPLACED GAPS QUESTIONABLE 186SL072630044YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL072630045---- --- -------------------- --------------- -------------------- 186SL0726300461975 67 none none none 186SL0726300471976 67 245-366 none none 186SL0726300481977 59 1-115,228-263 none none 186SL0726300491978 100 none none none 186SL0726300501979 96 33-46 (05)133-(20)133 none 186SL072630051 (14)192-(06)193 186SL0726300521980 99 37-39 (20)033-(06)034 none 186SL072630053 (16)043-(00)044 186SL0726300541981 69 68-70,112-219, none none 186SL072630055 358-360 186SL0726300561982 99 151-152,187-188 none none 186SL0726300571983 82 48-76,122-161, (07)173-(17)173 none 186SL072630058 349-365 186SL0726300591984 0 1-366 none none 186SL0726300601985 80 1-26,246-248, (21)204-(03)205 none 186SL072630061 266-277,324-326, 186SL072630062 331-365 186SL0726300631986 58 1-21,40-67, (21)025-(04)026 112-113 186SL072630064 172-199,239-245, (08)029-(16)029 186SL072630065 255-258,259-270, (05)037-(16)037 186SL072630066 284-341 (06)038-(13)038 186SL072630067 (22)038-(05)039 186SL072630068 (12)039-(20)039 186SL072630069 (03)144-(15)144 186SL072630070 (04)146-(19)146 186SL072630071 (04)147-(12)147 186SL072630072 (15)148-(02)149 186SL072630073 (17)150-(00)151 186SL072630074 (03)156-(13)156 186SL0726300751987 42 14-40,53-161, none 13-14 186SL072630076 215-230,231-293 186SL0726300771988 52 1-5,115-133, none 107-108,136-137,167, 186SL072630078 198-200 202-203,206-207 186SL072630079 186SL072630080 QUALITY ASSESSMENT POLICY 186SL072630081 186SL072630082 The quality assessment is mostly based on the residuals 186SL072630083 (observed data minus predicted tides) of the hourly data. This 186SL072630084 assessment also applies to the daily and monthly data since 186SL072630085 they were derived from the quality-controlled hourly data. 186SL072630086 186SL072630087 The following abbreviations are used in the assessment: 186SL072630088 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL072630089 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL072630090 research program; NODC - National Oceanographic Data Center; 186SL072630091 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL072630092 Gaps > 1 mon - missing data in a span greater than one month; 186SL072630093 Refernce - reference. 186SL072630094 186SL072630095 The following corrections are made to the hourly data 186SL072630096 prior to this assessment: 186SL072630097 1) Gaps or obviously wrong data points in a span less than 186SL072630098 25 hours are filled by the predicted tide method*. 186SL072630099 2) Timing errors of exact increments of an hour are corrected 186SL072630100 by shifting the data. 186SL072630101 3) Reference level shifts are only corrected after information 186SL072630102 from tide staff readings or comparative readings with a fixed 186SL072630103 bench mark are checked to verify that the shift was not a 186SL072630104 natural event. If comparative readings are missing or 186SL072630105 incomplete, comparisons of the data with nearby stations 186SL072630106 may warrant the adjustment of some obvious shifts. 186SL072630107 4) Data with unresolved datum shifts are not disseminated. 186SL072630108 However, if sufficient time spans of data are available before 186SL072630109 or after the year(s) with the unresolved shift(s), a subset of 186SL072630110 quality assured data is made available. Thus, the Span field 186SL072630111 in the Quality Assessment may not match the span of the 186SL072630112 distribution data set. As the questionable datum shifts are 186SL072630113 resolved, the data set will be updated. Although this policy 186SL072630114 adds some complexity, it allows more rapid dissemination of 186SL072630115 at least the quality assured years. 186SL072630116 186SL072630117 For each year, the following information is documented from 186SL072630118 the quality-controlled hourly data with dates given as the nth 186SL072630119 day of the year starting from 1 January: 186SL072630120 1) a Completeness Index (CI) based on the percentage of hours 186SL072630121 with available data, 186SL072630122 2) a list of gaps longer than a day, 186SL072630123 3) a summary of days with consecutive missing or obviously 186SL072630124 wrong data in a time span longer than 6 but less than 25 186SL072630125 hours that have been replaced, with hours in parentheses, and 186SL072630126 4) a summary of days with questionable fluctuations in the 186SL072630127 residual series. Fluctuations within the residuals are 186SL072630128 considered significant and are noted if they are greater than 186SL072630129 25 cm. This policy has changed slightly as of October 1992: 186SL072630130 only suspicious fluctuations due to obvious instrumentation 186SL072630131 problems are noted. Minor timing drifts are no longer 186SL072630132 included in the list of questionable days. 186SL072630133 186SL072630134 Note : If the predicted tides poorly model the observed heights 186SL072630135 due to the inability of the tidal analysis to completely resolv 186SL072630136 the non-linear shallow water effects, the residuals are not 186SL072630137 suitable for assessing the data quality. Instead, a subjective 186SL072630138 comment on the quality of the data is provided. 186SL072630139 186SL072630140 *The predicted tides are obtained with the use of a harmonic 186SL072630141 analysis program (Foreman, 1977) which is executed on a year 186SL072630142 of apparently good data for a given station. The Predicted 186SL072630143 Tide Method for filling gaps consists of statistically 186SL072630144 comparing the predicted tides to the observed data and 186SL072630145 shifting the predicted tides in time to correct for timing 186SL072630146 differences. Then the linear interpolation between hourly 186SL072630147 values at the end points of the gap in the residual series is 186SL072630148 added to the corresponding corrected predicted tide data to 186SL072630149 obtain interpolated values over the span of the gap. 186SL072630150 186SL072630151 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL072630152 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL072630153 186SL072630154 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL072630155 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL072630156 Victoria B.C. Pacific Marine Science Report 77-10. 186SL072630157 186SL07266 19751 99999999999999999999999999999999 1518010 1597000 186SL07266 19752 1682000 1709000 1778000 1685000 1636000 1547000 186SL07266 19761 1529000 1470000 1500000 1523000 1574000 1711000 186SL07266 19762 1836000 182100099999999999999999999999999999999 186SL07266 19771 99999999999999999999999999999999 1654000 1655000 186SL07266 19772 17340009999999999999999 1802000 1747000 1662000 186SL07266 19781 1626000 1616000 1575000 1598000 1606000 1630000 186SL07266 19782 1709000 1791000 1815000 1817000 1678000 1593000 186SL07266 19791 152100099999999 1573000 1594000 1612000 1660000 186SL07266 19792 1764000 1812000 1866000 1836000 1687000 1633000 186SL07266 19801 1592000 1630010 1598000 1598000 1640000 1718000 186SL07266 19802 1759000 1837000 1886000 1765000 1706000 1595000 186SL07266 19811 1600000 1567000 1554030999999999999999999999999 186SL07266 19812 99999999 1806070 1829000 1829000 1718000 1660030 186SL07266 19821 1587000 1604000 1619000 1645000 1681010 1768010 186SL07266 19822 1819020 1879000 1947000 1918000 1853000 1813000 186SL07266 19831 18080009999999999999999 17110009999999999999999 186SL07266 19832 1933000 1925000 1966000 1854000 176100099999999 186SL07266 19841 999999999999999999999999999999999999999999999999 186SL07266 19842 999999999999999999999999999999999999999999999999 186SL07266 19851 99999999 1559000 1553000 1536000 1592000 1652000 186SL07266 19852 1725000 176100099999999 1750040 166007099999999 186SL07266 19861 999999999999999999999999 1564000 159000099999999 186SL07266 19862 99999999 1740050999999999999999999999999 1563070 186SL07266 19871 999999999999999999999999999999999999999999999999 186SL07266 19872 1834000999999999999999999999999 1697000 1568000 186SL07266 19881 1395050 1391000 1397000 140907099999999 1505000 186SL07266 19882 16140409999999999999999999999999999999999999999