1. Introduction
The study of sea level change rate from tidal data is complicated by
the fact that tide gauges are attached to the land and thus their
measurements are affected by vertical land motion caused by natural
or anthropogenic processes unrelated to variations in sea level. In the
traditional approach of many global studies, e.g. Douglas (1997) and
Peltier (2001), only a subset of tide gauges is carefully selected, having
at least 60 years of record length and being far away from tectonically
active areas. Corrections for Global Isostatic Adjustment (GIA) are
then applied to obtain absolute rates of sea level change, which
produce a consistent rising rate at around 1.8 mm/yr for the 20th
century. The main problem with this approach is that the strict criteria
screen out most tide gauges, leaving only around 25 stations for
studying sea level change. Moreover the locations of these qualified
stations are concentrated in the Mediterranean, the North Atlantic
and the East Pacific. No tide gauges from the Indian Ocean and West
Pacific are included and the serious question arises whether this rate
can be truly regarded as global.
More recent studies on the trend and acceleration of global sea
level change mitigate this under-sampling problem by incorporating
as many tide gauges as possible, excluding only those in locations
where vertical movements (caused by tectonic activities or land
subsidence) are known to exist but with rates that cannot be
modelled. In Church and White (2006) the global sea level rise rate
and acceleration were determined from sea level reconstructed from
the amplitude derived from tidal data and the covariance obtained
from empirical orthogonal function analysis (EOF) of altimetry data.
Jevrejeva et al. (2006) and Jevrejeva et al. (2008) used a method based
on Monte Carlo Singular Spectrum Analysis (MC-SSA, quite similar to
EOF), to decompose the original tide gauge time series to detect multidecadal
oscillations of sea level change and its acceleration, which
1. IntroductionThe study of sea level change rate from tidal data is complicated bythe fact that tide gauges are attached to the land and thus theirmeasurements are affected by vertical land motion caused by naturalor anthropogenic processes unrelated to variations in sea level. In thetraditional approach of many global studies, e.g. Douglas (1997) andPeltier (2001), only a subset of tide gauges is carefully selected, havingat least 60 years of record length and being far away from tectonicallyactive areas. Corrections for Global Isostatic Adjustment (GIA) arethen applied to obtain absolute rates of sea level change, whichproduce a consistent rising rate at around 1.8 mm/yr for the 20thcentury. The main problem with this approach is that the strict criteriascreen out most tide gauges, leaving only around 25 stations forstudying sea level change. Moreover the locations of these qualifiedstations are concentrated in the Mediterranean, the North Atlanticand the East Pacific. No tide gauges from the Indian Ocean and WestPacific are included and the serious question arises whether this ratecan be truly regarded as global.More recent studies on the trend and acceleration of global sealevel change mitigate this under-sampling problem by incorporatingas many tide gauges as possible, excluding only those in locationswhere vertical movements (caused by tectonic activities or landsubsidence) are known to exist but with rates that cannot beคือ แบบจำลอง คริสตจักรและขาว (2006) จากระดับน้ำทะเลทั่วโลกเพิ่มขึ้นอัตราและเร่งความเร็วถูกกำหนดจากเชิดจากระดับน้ำทะเลคลื่นที่มาจากข้อมูลที่บ่าและแปรปรวนได้จากฟังก์ชัน orthogonal ประจักษ์ (EOF) วิเคราะห์ข้อมูล altimetryใช้วิธีการตาม Jevrejeva et al. (2006) และ Jevrejeva et al. (2008)ในมอน Carlo เอกพจน์วิเคราะห์สเปกตรัม (MC-SSA คล้ายกับEOF), การเปื่อยชุดเวลามาตรวัดน้ำตรวจหา multidecadal เดิมการแกว่งของระดับน้ำทะเลเปลี่ยนแปลงและการเร่งความเร็ว การ
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