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Valparaiso-B (Chile) Site History

History Summary

Reference Level

The originators have related the data to tide staff zero which is linked to a fixed set of benchmarks. Specifically, BM #2 (established 1941) is used as a historical datum. However, the data have several segments with questionable levelling that can not be corrected with levelling information from SHOA or from the original rolls, which have been misplaced:

Several segments with obvious shifts have warranted adjustment based on comparisons with Caldera and analysis of residuals (observed data minus predicted tides). These adjustements contain uncertainty of a few cm.

Data from 1988-1990 were received with the reference level tied to the BM #2 (1941) while data for other time periods were received without linking the data to BM #2. Thus, the following level adjustments have been applied to the original data based on SHOA geodetic level records:

This series is independent of Valparaiso-A because of a large unresolved reference level jump.

Tide Gauge Benchmark (TGBM) Description

Benchmark Relationships

BM Control - 1985-1990.

BM No. 7 - 1950-1990.

Quality Assessment by the UH Sea Level Centre

Comment

The daily means agree reasonably with Caldera before the earthquake of 3/3/85 with the exception of the questionable segments as noted above. After 15/07/85, the linearly increasing trend ends and the daily means then agree well with Caldera. The linear trend of 3/3/85-15/07/85 is associated with the subsidence of the adjacent land and the pier which supports the installation. * below indicates gaps filled with Encoder data, # for Bubbler data (received via satellite), and $ for AAG. In comparison with the NOAA gauge, this series is suspiciously high by 5 cm from 8 July to 23 August 1996.

The extreme peak on 17 August 1997 is due to a storm.