QUALITY ASSESSMENT OF SEA LEVEL DATA by the UH SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER JOINT ARCHIVE FOR SEA LEVEL updated: 12 Jul 1999 Station : Arica Latitude: 18 28.0S Country : Chile Longitude: 070 20.0W JASL # : 083A Time Meridian: 060W (GMT - 4 hr) GLOSS # : none Originator #:0210 NODC #: 51078001 Contributor : Servicio Hidrografico y Oceanografico de la Armada (SHOA) Casilla 324 Valparaiso CHILE Originator : same Original Data: analog (mechanical,bubbler); digital (encoder) Instrmnt Type: standard mechanical (10/1982 - 12/1985); Metercraft bubbler (12/1985 - present) (primary); Handar Encoder model 436A (11/1986-present) (back- up) Digitzd Intvl: one hour (mechanical,bubbler); 4 min (encoder) Present Data : Hourly, daily, and monthly values obtained by: Hourly : The original digitizing interval was hourly (analog); a Hanning three-point filter centered on the hour (Encoder) Daily : 119-point convolution filter (Bloomfield, 1976) centered on noon applied to the hourly data with respective periods of the 95, 50, and 5% amplitude points at 124.0, 60.2, and 40.2 hours Monthly: Simple average of all daily values; calculated if 7 or fewer days are missing Span of data : 03 Oct 1982 - 31 Dec 1998 Gaps > 1 mon : 31 Jan - 7 Mar 1984; 1 Jan - 9 Feb 1983 Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 Units : millimeters Missing Data Flag : 9999 Existing : Yes Operational : Yes Sat. Trans. : Yes Distribution : 1982-1998 Refernce Levl: The originators have related the data to tide staff zero which is linked to a fixed set of bench marks. Specifically, BM #1 (established 1950) is used as a historical datum. However, original data as received from SHOA were adjusted with the SHOA station leveling data as follows. value added period( day/month/year ) to original(mm) ------------------------ --------------- *14/07/1983 - 31/08/1983 -140 09/06/1987 - 31/12/1987 504 23/10/1990 - 25/10/1990 130 &28/07/1993 - 27/09/1993 -55 *Adjustment of shift in reference level deduced from the plot of hourly residuals and from comparison of daily values with Antofagasta and Caldera. &Based on comparisons with satellite-received data at the University of Hawaii and comparisons among neighboring sites. These adjustments contains uncertainty of a few centimeters. Data from 1988-1990 were received with the reference level tied to the BM #1 (1950) while data for other time periods were received without linking the data to BM #1. Thus, the following level adjustments have been applied to the original data based on SHOA geodetic level records: value added period( day/month/year ) to original(mm) ------------------------ --------------- 01/01/1982-31/12/1987 -256 01/01/1991-24/04/1995 243 24/04/1995-31/12/1996 -460 01/01/1997-31/12/1998 -217 Comment : The daily and monthly values agree well with the nearest station, Antofagasta, and there are no obvious reference level shifts, except that mid-July 1992 to Dec 1992 appears about 5 cm low and 28 July - 27 Sept 1993 appears about 6 cm high compared with other sites and the satellite- received data for same time period. # below indicates gaps filled with Bubbler data received at the UH Sea Level Center via satellite and $ below refers to gaps filled with Encoder data. CI MISSING REPLACED GAPS QUESTIONABLE YEAR (%) DATA OR BAD DATA FLUCTUATIONS ---- --- -------------------- --------------- -------------------- 1982 24 1-275 (21)237-(11)238 296,318 1983 86 1-40,61-74 (21)120-(03)121 56-60,182-183 (03)195-(01)196 (16)212-(03)213 (21)267-(13)268 1984 88 31-67,111-116 none 120 1985 94 87-88,181-201 (16)030-(13)031 63,80,123-124 (22)173-(13)174 (16)243-(03)244 (14)273-(03)274 1986 100 none (01)237-(13)237 none (14)365-(23)365 1987 100 none (15)089-(13)090 none (04)161-(03)162 1988 100 none (14)014-(13)015 6-7,64-65,95-96 (21)066-(13)067 (06)068-(13)068 (23)069-(06)070 (21)131-(12)132 (06)183-(16)183 (01)188-(12)188 (04)189-(02)190 (15)275-(21)275 (20)331-(11)332 #(05)002-(12)004 #(23)061-(07)064 #(14)092-(05)095 #(15)149-(13)152 #(05)157-(05)158 #(10)184-(02)186 1989 100 none (04)099-(13)099 none (11)168-(03)169 (05)275-(12)275 (21)317-(14)318 #(13)091-(14)092 #(04)172-(13)188 #(01)196-(18)198 1990 99 334-336 (23)328-(13)329 15-17 (01)351-(14)351 #(23)020-(13)023 #(05)121-(13)122 #(19)138-(15)141 #(16)334-(06)336 1991 100 none #(02)142-(13)143 none 1992 100 none (17)124-(11)125 184-185,249-252,269- (14)293-(13)294 270,302-303 1993 100 none (15)005-(14)006 38-39 (01)067-(13)067 (18)090-(23)090 (01)091-(11)091 #(00)333-(18)340 1994 100 none $(08)058-(23)059 none (16)117-(13)118 (20)313-(11)314 (19)328-(06)329 (21)329-(04)330 (16)331-(12)332 1995 99 251-253 (14)069-(13)070 none $(00)074-(23)092 (15)121-(03)122 $(00)213-(12)218 $(12)306-(23)308 (19)316-(12)317 $(00)350-(23)351 1996 100 none (00)082-(12)082 none $(00)094-(23)097 $(00)112-(23)116 $(00)217-(23)218 $(00)226-(23)227 (04)306-(13)306 $(12)356-(23)361 1997 100 none $(00)001-(15)002 $(23)010-(12)016 $(31)031-(11)034 $(04)041-(12)062 $(21)064-(17)069 $(15)075-(15)076 (14)087-(12)088 (20)117-(13)118 (12)119-(03)120 (05)296-(13)296 (06)298-(13)298 (00)299-(16)299 (22)299-(19)300 (22)300-(16)301 (22)301-(19)302 (02)334-(14)334 (05)341-(12)341 1998 100 none (00)001-(18)001 none (17)034-(12)035 (22)092-(12)093 (21)193-(14)194 (04)195-(19)195 #(00)274-(23)283