186SL0960112112501 641A 19750101 19901231 2245N 11521E 2 00000R 0000 MM 186SL0960212112501 Shanwei China PRC Nat. Ocean. Data Center 186SL096030001 186SL096030002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL096030003 by the 186SL096030004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL096030005 JOINT ARCHIVE FOR SEA LEVEL 186SL096030006 186SL096030007Station : Shanwei Latitude: 22 45.0N 186SL096030008Country : China Longitude: 115 21.0E 186SL096030009JASL # : 641A Time Meridian: 120E (GMT + 8 hr) 186SL096030010GLOSS # : none TOGA #: none NODC #: 12112501 186SL096030011Contributor : PRC National Oceanographic Data Center 186SL096030012 118, Qiwei Road, Hedong 186SL096030013 District Tianjin, China 186SL096030014Originator : same 186SL096030015Original Data: analog 186SL096030016Instrmnt Type: HCJ-1 Float gauge (1975-1985); 186SL096030017 SCA1-1 Float gauge (1986-1990) 186SL096030018Digitzd Intvl: hourly 186SL096030019Present Data : Hourly, daily, and monthly values obtained by: 186SL096030020 Hourly : digitized as hourly values 186SL096030021 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL096030022 centered on noon applied to the hourly data 186SL096030023 with respective periods of the 95, 50, and 5% 186SL096030024 amplitude points at 124.0, 60.2, and 40.2 hours 186SL096030025 Monthly: Simple average of all daily values; calculated if 186SL096030026 7 or fewer days are missing 186SL096030027Span of data : 01 Jan 1975 - 31 Dec 1990 186SL096030028Gaps > 1 mon : none 186SL096030029Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 186SL096030030Units : millimeters Missing Data Flag :99999 186SL096030031Refernce Levl: The sea level heights are referred to the Tide 186SL096030032 Gauge Zero (TGZ) which is linked to fixed bench 186SL096030033 marks. Bench mark information is 186SL096030034 available upon request from the contributors. 186SL096030035Comment : The residual series are very noisy which are 186SL096030036 probably due to shallow water tides that are not 186SL096030037 resolved by the harmonic analysis. Also the daily 186SL096030038 plot shows noise due to a great amount of energy 186SL096030039 with periods from 1 to 5 days. The mean level is 186SL096030040 steady. This data set is of good quality. 186SL096030041 186SL096030042 CI MISSING REPLACED GAPS QUESTIONABLE 186SL096030043YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL096030044---- --- -------------------- --------------- -------------------- 186SL0960300451975 100 none none see comment above 186SL0960300461976 100 none none see comment above 186SL0960300471977 100 none none see comment above 186SL0960300481978 100 none none see comment above 186SL0960300491979 100 none (01)187-(11)187 see comment above 186SL0960300501980 100 none none see comment above 186SL0960300511981 100 none none see comment above 186SL0960300521982 100 none none see comment above 186SL0960300531983 100 none none see comment above 186SL0960300541984 100 none none see comment above 186SL0960300551985 100 none none see comment above 186SL0960300561986 100 none none see comment above 186SL0960300571987 100 none none see comment above 186SL0960300581988 100 none none see comment above 186SL0960300591989 100 none none see comment above 186SL0960300601990 99 365 none see comment above 186SL096030061 186SL096030062 QUALITY ASSESSMENT POLICY 186SL096030063 186SL096030064 The quality assessment is mostly based on the residuals 186SL096030065 (observed data minus predicted tides) of the hourly data. This 186SL096030066 assessment also applies to the daily and monthly data since 186SL096030067 they were derived from the quality-controlled hourly data. 186SL096030068 186SL096030069 The following abbreviations are used in the assessment: 186SL096030070 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL096030071 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL096030072 research program; NODC - National Oceanographic Data Center; 186SL096030073 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL096030074 Gaps > 1 mon - missing data in a span greater than one month; 186SL096030075 Refernce - reference. 186SL096030076 186SL096030077 The following corrections are made to the hourly data 186SL096030078 prior to this assessment: 186SL096030079 1) Gaps or obviously wrong data points in a span less than 186SL096030080 25 hours are filled by the predicted tide method*. 186SL096030081 2) Timing errors of exact increments of an hour are corrected 186SL096030082 by shifting the data. 186SL096030083 3) Reference level shifts are only corrected after information 186SL096030084 from tide staff readings or comparative readings with a fixed 186SL096030085 bench mark are checked to verify that the shift was not a 186SL096030086 natural event. If comparative readings are missing or 186SL096030087 incomplete, comparisons of the data with nearby stations 186SL096030088 may warrant the adjustment of some obvious shifts. 186SL096030089 4) Data with unresolved datum shifts are not disseminated. 186SL096030090 However, if sufficient time spans of data are available before 186SL096030091 or after the year(s) with the unresolved shift(s), a subset of 186SL096030092 quality assured data is made available. Thus, the Span field 186SL096030093 in the Quality Assessment may not match the span of the 186SL096030094 distribution data set. As the questionable datum shifts are 186SL096030095 resolved, the data set will be updated. Although this policy 186SL096030096 adds some complexity, it allows more rapid dissemination of 186SL096030097 at least the quality assured years. 186SL096030098 186SL096030099 For each year, the following information is documented from 186SL096030100 the quality-controlled hourly data with dates given as the nth 186SL096030101 day of the year starting from 1 January: 186SL096030102 1) a Completeness Index (CI) based on the percentage of hours 186SL096030103 with available data, 186SL096030104 2) a list of gaps longer than a day, 186SL096030105 3) a summary of days with consecutive missing or obviously 186SL096030106 wrong data in a time span longer than 6 but less than 25 186SL096030107 hours that have been replaced, with hours in parentheses, and 186SL096030108 4) a summary of days with questionable fluctuations in the 186SL096030109 residual series. Fluctuations within the residuals are 186SL096030110 considered significant and are noted if they are greater than 186SL096030111 25 cm. This policy has changed slightly as of October 1992: 186SL096030112 only suspicious fluctuations due to obvious instrumentation 186SL096030113 problems are noted. Minor timing drifts are no longer 186SL096030114 included in the list of questionable days. 186SL096030115 186SL096030116 Note : If the predicted tides poorly model the observed heights 186SL096030117 due to the inability of the tidal analysis to completely resolv 186SL096030118 the non-linear shallow water effects, the residuals are not 186SL096030119 suitable for assessing the data quality. Instead, a subjective 186SL096030120 comment on the quality of the data is provided. 186SL096030121 186SL096030122 *The predicted tides are obtained with the use of a harmonic 186SL096030123 analysis program (Foreman, 1977) which is executed on a year 186SL096030124 of apparently good data for a given station. The Predicted 186SL096030125 Tide Method for filling gaps consists of statistically 186SL096030126 comparing the predicted tides to the observed data and 186SL096030127 shifting the predicted tides in time to correct for timing 186SL096030128 differences. Then the linear interpolation between hourly 186SL096030129 values at the end points of the gap in the residual series is 186SL096030130 added to the corresponding corrected predicted tide data to 186SL096030131 obtain interpolated values over the span of the gap. 186SL096030132 186SL096030133 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL096030134 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL096030135 186SL096030136 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL096030137 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL096030138 Victoria B.C. Pacific Marine Science Report 77-10. 186SL096030139 186SL09606 19751 1329000 1295000 1324000 1224000 1269000 1225000 186SL09606 19752 1105000 1290000 1323000 1546000 1495000 1439000 186SL09606 19761 1318000 1313000 1274000 1277000 1294000 1254000 186SL09606 19762 1299000 1267000 1530000 1434000 1464000 1282000 186SL09606 19771 1349000 1282000 1184000 1168000 1181000 1155000 186SL09606 19772 1264000 1272000 1518000 1435000 1433000 1329000 186SL09606 19781 1233000 1228000 1272000 1210000 1272000 1232000 186SL09606 19782 1224000 1327000 1443000 1611000 1388000 1311000 186SL09606 19791 1171000 1184000 1265000 1256000 1307000 1249000 186SL09606 19792 1246000 1275000 1400000 1555000 1434000 1263000 186SL09606 19801 1222000 1269000 1255000 1245000 1309000 1173000 186SL09606 19802 1213000 1244000 1480000 1459000 1436000 1377000 186SL09606 19811 1353000 1327000 1222000 1256000 1223000 1317000 186SL09606 19812 1272000 1272000 1358000 1497000 1492000 1360000 186SL09606 19821 1253000 1265000 1235000 1266000 1226000 1292000 186SL09606 19822 1237000 1161000 1436000 1402000 1299000 1304000 186SL09606 19831 1270000 1302000 1306000 1216000 1220000 1228000 186SL09606 19832 1181000 1261000 1311000 1466000 1441000 1354000 186SL09606 19841 1327000 1338000 1235000 1265000 1285000 1254000 186SL09606 19842 1150000 1382000 1285000 1509000 1452000 1325000 186SL09606 19851 1221000 1290000 1335000 1209000 1192000 1398000 186SL09606 19852 1182000 1253000 1371000 1437000 1383000 1335000 186SL09606 19861 1238000 1284000 1287000 1219000 1248000 1212000 186SL09606 19862 1275000 1422000 1426000 1421000 1457000 1332000 186SL09606 19871 1283000 1217000 1193000 1228000 1212000 1266000 186SL09606 19872 1172000 1194000 1396000 1411000 1403000 1401000 186SL09606 19881 1316000 1329000 1342000 1281000 1272000 1228000 186SL09606 19882 1194000 1211000 1394000 1671000 1429000 1301000 186SL09606 19891 1365000 1291000 1279000 1218000 1297000 1242000 186SL09606 19892 1293000 1365000 1417000 1532000 1484000 1358000 186SL09606 19901 1385000 1262000 1220000 1279000 1249000 1273000 186SL09606 19902 1225000 1343000 1411000 1496000 1436000 1298010