Isla da Pascua-E (Chile) Site History

History Summary

Station Isla da Pascua-E
Country Chile
Latitude 27° 09.0' S
Longitude 109° 26.9' W
GLOSS No 137
Time Reference GMT (hours 00-23)
Contributor Servicio Hidrografico y Oceanografico de la Armada (SHOA)
For 1994+ data also from National Ocean Service (NOS) National Ocean. and Atmos. Administration (NOAA)
Instrument Type
  • Bristol bubbler gauge (BUB) (primary gauge 1985-01/1994)
  • NOAA "digibub" water level gauge (PRS) (primary gauge 03/1994+). Note: this gauge uses a nitrogen-driven bubbler oriface below the water line connected to a Para-scientific pressure transducer located at the DCP housing. The pressure transducers are vented to the atmosphere so no atmospheric corrections are required.

  • NOAA backup pressure water level gauge (BWL)
Site of Gauge  
Observational periods 1985 - present

Reference Level

The data have been linked to tide staff zero which is leveled to fixed benchmarks. These benchmarks are not linked to the benchmarks used by other data sets for Easter Island; thus, this data record is independent. A reference level shift has been identified in the analog rolls by the originators and an adjustment was applied:

Period ((hh)day/month/year) Value Added to
Original(mm)
(06)01/11/1988-(00)06/02/89 +100

The period after the long gap in 1991 appears to have a lower mean level although data received via satellite also show this feature. It is not clear if a reference shift occurred during the gap.

Benchmarks

Benchmark Description
BM No. 15
(TGBM)
It is a 6cm bronze disk stamped CF 15, set in cement on the right corner at the front of the tide house base.
BM No. 16
(Auxilliary)
It is a 6cm bronze disk stamped CF 16, set in cement at the south west corner of the warehouse located 150m south of the tide house.
BM No. 17
(Auxilliary)
It is a 6cm bronze disk stamped CF 17, set in cement at the gate of the cold storage plant.

Quality Assessment by the UH Sea Level Center

Comment

Some questionable fluctuations of nearly a one-day duration during the winter months are related to weather events. The daily and monthly means reveal no apparent changes in the reference level. However, in comparison with the satellite-received data at the University of Hawaii, the difference plot of daily means shows a possible shift around 27 August 1986 (+7 cm). This difference plot also shows some other subtle shifts. The originators have checked the tide staff observation sheets and the analog rolls and found no problems.

The gaps filled below flagged '*' used redundant satellite-received data that were decimated to hourly with a spot sample technique. '$' below denotes that the PRS series was filled with BUB data.

Year CI (%) Missing Data Replaced Gaps or Bad Data Questionable Fluctuations
1985 98 1,127-128,249-250 (18)091-(06)092 (21)112-(13)113 (16)131-(00)132 (12)347-(19)347 (14)361-(00)362 132-133,154-155, 176-181
1986 100 none none 63-64,66,93-95
1987 100 none (23)335-(16)336 (20)342-(19)343 *(16)121-(21)123 *(17)365-(22)001 24-27,96-98,163,255,276
1988 100 none (06)182-(23)182 (23)271-(16)272 (10)289-(19)289 (08)305-(15)305 *(09)068-(18)069 *(00)093-(15)094 *(16)153-(23)155 *(20)253-(23)255 *(06)301-(14)302 21-22,42,45-47,73-77,111,129-130,135
1989 92 36-67 (07)067-(02)068 (12)121-(23)121 (11)274-(05)275 (14)318-(19)318 324-325
1990 98 58-66 (05)010-(17)010 (17)357-(13)358 (05)360-(16)360 *(01)125-(15)134 *(02)361-(17)362 *(03)363-(23)365 none
1991 57 49-208 (18)030-(13)031 (07)034-(14)034 (03)040-(14)040 (01)043-(16)043 (00)227-(13)227 (17)243-(23)243 (01)244-(15)244 (20)259-(16)260 243
1992 100 none none none
1993 100 none (18)252-(04)253 (16)349-(15)350 *(07)017-(07)020 *(15)031-(21)035 *(20)047-(12)049 *(22)074-(16)076 *(16)103-(15)105 256-257,261-265
1994 100 none $(18)032-(21)059 $(20)091-(08)094 33-37,92-93
1995 100 none none none
1996 100 none none none
1997 99 221-224 #(12)212-(23)227 #(00)260-(23)262 none
1998 99 60-62 (07)032-(17)032 (07)091-(15)091 #(18)306-(00)308 #(01)333-(05)335 (21)338-(15)339 none