186SL0747111123301 371A 19840101 19900630 1309N 12345E 2 00000R 0000 MM 186SL0747211123301 Legaspi Philippines Ocean. Surveys Division 186SL074730001 186SL074730002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL074730003 by the 186SL074730004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL074730005 JOINT ARCHIVE FOR SEA LEVEL 186SL074730006 186SL074730007Station : Legaspi Latitude: 13 09.0N 186SL074730008Country : Philippines Longitude: 123 45.0E 186SL074730009JASL # : 371A Time Meridian: 120E (GMT + 8 hr) 186SL074730010GLOSS # : 072 TOGA #: P010 NODC #: 11123301 186SL074730011Contributor : Oceanographic Surveys Division 186SL074730012 NAMRIA, Binondo Branch 186SL074730013 P. O. Box 1620 186SL074730014 Manila, Philippines 186SL074730015Originator : same 186SL074730016Original Data: analog 186SL074730017Instrmnt Type: A.OTT, gravity type 186SL074730018Digitzd Intvl: one hour 186SL074730019Present Data : Hourly, daily, and monthly values obtained by: 186SL074730020 Hourly : The original digitizing interval was hourly 186SL074730021 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL074730022 centered on noon applied to the hourly data 186SL074730023 with respective periods of the 95, 50, and 5% 186SL074730024 amplitude points at 124.0, 60.2, and 40.2 hours 186SL074730025 Monthly: Simple average of all daily values; calculated if 186SL074730026 7 or fewer days are missing 186SL074730027Span of data : 01 Jan 1984 - 30 Jun 1990 186SL074730028Gaps > 1 mon : none 186SL074730029Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 186SL074730030Units : millimeters Missing Data Flag :99999 186SL074730031Refernce Levl: All data are referred to a historic fixed 186SL074730032 bench mark 186SL074730033Comment : A timing offset of 30 minutes exists from 16Z 186SL074730034 31 Jan - 15Z 11 Feb 1985. Otherwise the daily and 186SL074730035 monthly means do not reveal any obvious reference 186SL074730036 level changes. Significant meteorological events: 186SL074730037 186SL074730038 period (dd/mm/yyyy) event 186SL074730039 ------------------- --------------- 186SL074730040 12/10 - 30/10/1985 typhoons 186SL074730041 17/10 - 20/10/1986 tropical storm 186SL074730042 06/11 - 10/11/1986 tropical storm 186SL074730043 18/11 - 24/11/1986 typhoon 186SL074730044 186SL074730045 CI MISSING REPLACED GAPS QUESTIONABLE 186SL074730046YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL074730047---- --- -------------------- --------------- -------------------- 186SL0747300481984 100 none none none 186SL0747300491985 100 none none 31-42 186SL0747300501986 100 none none 180-182 186SL0747300511987 100 none none 85-91,224,308,312, 186SL074730052 330-333,337 186SL0747300531988 100 none none 119,293-294 186SL0747300541989 100 none none 31-33,43,264,267- 186SL074730055 268,283 186SL0747300561990 50 none none 37,56,124,129-130, 186SL074730057 145,152-155,178-181 186SL074730058 186SL074730059 QUALITY ASSESSMENT POLICY 186SL074730060 186SL074730061 The quality assessment is mostly based on the residuals 186SL074730062 (observed data minus predicted tides) of the hourly data. This 186SL074730063 assessment also applies to the daily and monthly data since 186SL074730064 they were derived from the quality-controlled hourly data. 186SL074730065 186SL074730066 The following abbreviations are used in the assessment: 186SL074730067 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL074730068 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL074730069 research program; NODC - National Oceanographic Data Center; 186SL074730070 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL074730071 Gaps > 1 mon - missing data in a span greater than one month; 186SL074730072 Refernce - reference. 186SL074730073 186SL074730074 The following corrections are made to the hourly data 186SL074730075 prior to this assessment: 186SL074730076 1) Gaps or obviously wrong data points in a span less than 186SL074730077 25 hours are filled by the predicted tide method*. 186SL074730078 2) Timing errors of exact increments of an hour are corrected 186SL074730079 by shifting the data. 186SL074730080 3) Reference level shifts are only corrected after information 186SL074730081 from tide staff readings or comparative readings with a fixed 186SL074730082 bench mark are checked to verify that the shift was not a 186SL074730083 natural event. If comparative readings are missing or 186SL074730084 incomplete, comparisons of the data with nearby stations 186SL074730085 may warrant the adjustment of some obvious shifts. 186SL074730086 4) Data with unresolved datum shifts are not disseminated. 186SL074730087 However, if sufficient time spans of data are available before 186SL074730088 or after the year(s) with the unresolved shift(s), a subset of 186SL074730089 quality assured data is made available. Thus, the Span field 186SL074730090 in the Quality Assessment may not match the span of the 186SL074730091 distribution data set. As the questionable datum shifts are 186SL074730092 resolved, the data set will be updated. Although this policy 186SL074730093 adds some complexity, it allows more rapid dissemination of 186SL074730094 at least the quality assured years. 186SL074730095 186SL074730096 For each year, the following information is documented from 186SL074730097 the quality-controlled hourly data with dates given as the nth 186SL074730098 day of the year starting from 1 January: 186SL074730099 1) a Completeness Index (CI) based on the percentage of hours 186SL074730100 with available data, 186SL074730101 2) a list of gaps longer than a day, 186SL074730102 3) a summary of days with consecutive missing or obviously 186SL074730103 wrong data in a time span longer than 6 but less than 25 186SL074730104 hours that have been replaced, with hours in parentheses, and 186SL074730105 4) a summary of days with questionable fluctuations in the 186SL074730106 residual series. Fluctuations within the residuals are 186SL074730107 considered significant and are noted if they are greater than 186SL074730108 25 cm. This policy has changed slightly as of October 1992: 186SL074730109 only suspicious fluctuations due to obvious instrumentation 186SL074730110 problems are noted. Minor timing drifts are no longer 186SL074730111 included in the list of questionable days. 186SL074730112 186SL074730113 Note : If the predicted tides poorly model the observed heights 186SL074730114 due to the inability of the tidal analysis to completely resolv 186SL074730115 the non-linear shallow water effects, the residuals are not 186SL074730116 suitable for assessing the data quality. Instead, a subjective 186SL074730117 comment on the quality of the data is provided. 186SL074730118 186SL074730119 *The predicted tides are obtained with the use of a harmonic 186SL074730120 analysis program (Foreman, 1977) which is executed on a year 186SL074730121 of apparently good data for a given station. The Predicted 186SL074730122 Tide Method for filling gaps consists of statistically 186SL074730123 comparing the predicted tides to the observed data and 186SL074730124 shifting the predicted tides in time to correct for timing 186SL074730125 differences. Then the linear interpolation between hourly 186SL074730126 values at the end points of the gap in the residual series is 186SL074730127 added to the corresponding corrected predicted tide data to 186SL074730128 obtain interpolated values over the span of the gap. 186SL074730129 186SL074730130 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL074730131 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL074730132 186SL074730133 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL074730134 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL074730135 Victoria B.C. Pacific Marine Science Report 77-10. 186SL074730136 186SL07476 19841 1623000 1683000 1709000 1740000 1786000 1754000 186SL07476 19842 1796000 1828000 1753000 1766000 1752000 1692000 186SL07476 19851 1598000 1682000 1717000 1761000 1764000 1798000 186SL07476 19852 1748000 1742000 1725000 1695000 1650000 1701000 186SL07476 19861 1647000 1607000 1670000 1728000 1759000 1759000 186SL07476 19862 1748000 1711000 1669000 1643000 1656000 1570000 186SL07476 19871 1586000 1552000 1544000 1598000 1560000 1613000 186SL07476 19872 1708000 1714000 1768000 1735000 1815000 1714000 186SL07476 19881 1644000 1646000 1703000 1748000 1733000 1770000 186SL07476 19882 1778000 1804000 1842000 1829000 1837000 1803000 186SL07476 19891 1743000 1776000 1815000 1882000 1900000 1885000 186SL07476 19892 1880000 1878000 1812000 1806000 1757000 1669000 186SL07476 19901 1619000 1652000 1646000 1710000 1771000 1803010 186SL07476 19902 999999999999999999999999999999999999999999999999