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1 Recent Changes in Sea Level: A Summary
Pages 37-51

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From page 37... ... that will serve as basic reference for the discussion of the two different approaches to estimating RSL change and will offer abundant references for readers interested in delving further into the subject. SOME PRIOR STUDIES OF "GLOBAL" SEA LEVEL Sea-level stations are located mainly on coastal margins and a few islands. Read the entire page →
From page 38... ... Perhaps their most interesting result relates the observed change in rotation rate of the Earth to the estimated change in the polar ice caps. The apparent agreement so obtained in this comparison would be much less impressive, however, if they had not used the 3-mm/yr RSL rise figure of Emery. Read the entire page →
From page 39... ... 5. Geodetic leveling between sea-level stations apparently cannot be used to remove relative vertical motion of the land, if the stations are more than a few hundred kilometers apart. Read the entire page →
From page 40... ... was applied to the primary key station set and to the secondary station set to check sensitivity of the results to data perturbations. The sea-level data at position i are represented by Read the entire page →
From page 41... ... Indeed the implied decrease in RSL in the eastern Asian region TON is supported by independent hydrographic observations (e.g., White et al., 1979~. The implied RSL trend in Figure 1.5 is 1.79 + 0.22 mm/yr. Read the entire page →
From page 42... ... These results are qualitatively unaltered by substantial perturbation of the original set or method of normalization. ESTIMATES OF RSL CHANGE: AREA AVERAGE APPROACH Methods Selection of one or more unrepresentative stations in the key station approach can introduce spurious inforrnation into the resulting analysis. Read the entire page →
From page 43... ... , provided the hi represent the regional averages defined earlier and the By ale the mode-1 eigenvector components of the regional analysis. Note that the distribution of regional averages is roughly area representative of the respective oceans. Read the entire page →
From page 44... ... Since the first mode captured approximately 50 percent of the total variance, it contains the dominant signal in the sea-level set. Further, the in-phase eigencomponents were all of approximately equal magnitude, suggesting the uniformity of the relative sea-level variation associated with this mode. Read the entire page →
From page 45... ... Without an adequate global sealevel network, which is unlikely to exist in the near future, the estimate of "global" RSL change will remain an uncertain business. Tests of the different approaches mentioned above to obtain this average suggest that estimates of global change with current data can vary by a factor of 50 percent a scatter induced solely by the analysis method. Read the entire page →
From page 46... ... suggest that, at least near Bermuda, warming of the upper ocean can or cannot explain the local RSL change, the result depending on the length of record analyzed. This is clearly an unsatisfactory situat~on. Read the entire page →
From page 47... ... depending on relative changes in ice concentration as reflected in RSL changes. A crude history of the long-term migration of the rotation pole is shown in Figure 1.11 (Yumi and Yokoyama, 1980; actual data courtesy of D Read the entire page →
From page 48... ... and at first thought would seem an unimportant source of RSL change. However, mountain glaciers show large variability in time, and one needs only a 20 percent reduction in their volume to obtain the observed RSL increase. Read the entire page →
From page 49... ... It is possible, but unlikely, that a large part of the RSL change observed is due to vertical crustal motion alone. Fortunately, there are a number of other interesting hypotheses that could explain the RSL change. Read the entire page →
From page 50... ... , in Proceedings of the Meeting on Time Series of Ocean Measurements (Tokyo, Japan) , World Meteorological Organization. Read the entire page →
From page 51... ... (1981~. Oceanic time series measurements from station P and along line P in the Northeast Pacific Ocean, in Proceedings of the Meeting on Time Series of Ocean Measurements (Tokyo, Japan) Read the entire page →

From page 37...

... that will serve as basic reference for the discussion of the two different approaches to estimating RSL change and will offer abundant references for readers interested in delving further into the subject. SOME PRIOR STUDIES OF "GLOBAL" SEA LEVEL Sea-level stations are located mainly on coastal margins and a few islands.

1 Recent Changes in Sea Level: A Summary Pages 37-51

1 Recent Changes in Sea Level: A Summary
Pages 37-51