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Joint Estimation of Vertical Land Motion and Global Sea-Level Rise over the Past Six Decades Using Satellite Altimetry and Tide Gauge Records

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2015, Doctor of Philosophy, Ohio State University, Geodetic Science and Surveying.
Determination of the 20th and early 21st century sea level rise and understanding the geophysical causes leading to sea level rise is a significant scientific topic. Satellite radar altimeter has been providing continuous and near-global sea level measurements since 1992. Despite of the fact that multiple satellite altimeter measurements have reached a 23-year data record, it is still too short to isolate the definitive sea level rise signal from the contamination of interannual or longer oceanic variability. In contrast, global tide gauges measure the relative sea level and have data records as long as 200 years, but the measurements are susceptive to or contaminated by the vertical motion of the solid Earth. Despite the availability of geophysical models or collocated GPS stations at the tide gauge benchmarks, the separation of vertical land motions from long-term sea level signal in tide gauge records remains to be a challenge to be practically applicable to improve sea level rise projections. To improve the accuracy of altimeter estimated geocentric sea level over the last 23 years, we process altimeter data from different satellite missions. Least-squares collocation technique has been applied in the generation of multi-satellite altimeter gridded data products, 1992–2015, with updated estimates of reference frame offsets. Furthermore, we improved the sea level data record quality, based on comparisons with available in situ tide gauges and increased data points, over seasonally sea-ice covered Arctic Ocean from our reprocessed ERS-1 and ERS-2 altimeter measurements. Finally, our composite altimeter data set yielded a global sea level trend estimate of 2.8±0.6 mm/yr, and the regional trend estimate of 2.3±1.3 mm/yr for the Arctic Ocean, 1992–2015, respectively. To improve vertical land motion estimates at world’s tide gauge locations for the improved recovery of sea level rise signal, we proposed a new method, based on adjustment algorithm and sea level reconstruction, to combine radar altimeter and tide gauge data. First, we validated our multi-satellite altimeter sea level are consistent with in situ sea level from the global tide gauge network. Results comparing 559 globally distributed tide gauges show that our multi-satellite sea level data has an average correlation with tide gauge sea level at 0.85±0.09, and standard deviation of difference of 4.4±1.6 cm. Application of regional adjustment algorithms results in globally selected 158 tide gauge vertical motion estimates with the difference of –0.19±1.67 mm/yr against independent GPS@Tide gauge vertical motion solutions. The result is a significant improvement over the priori vertical motion estimates with an average difference of –0.11±3.15 mm/yr against the independent GPS rates. Finally, we further improved the algorithm with an iterative procedure to separate the vertical motion at 417 world’s tide gauges and sea level rise, by combining altimetry and tide gauge data to simultaneously estimate vertical motion at the tide gauge locations, and to reconstruct the global sea level variations, 1950–2012. The resulting vertical motion solution yields a discrepancy at 0.01±1.67 mm/yr against 210 independent GPS rates, and an average rate of global sea level rise at 1.70 mm/yr.
C.K. Shum (Advisor)
Christopher Jekeli (Committee Member)
Alan Saalfeld (Committee Member)
133 p.

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Citations

  • Wan, J. (2015). Joint Estimation of Vertical Land Motion and Global Sea-Level Rise over the Past Six Decades Using Satellite Altimetry and Tide Gauge Records [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1449185593

    APA Style (7th edition)

  • Wan, Junkun. Joint Estimation of Vertical Land Motion and Global Sea-Level Rise over the Past Six Decades Using Satellite Altimetry and Tide Gauge Records . 2015. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1449185593.

    MLA Style (8th edition)

  • Wan, Junkun. "Joint Estimation of Vertical Land Motion and Global Sea-Level Rise over the Past Six Decades Using Satellite Altimetry and Tide Gauge Records ." Doctoral dissertation, Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1449185593

    Chicago Manual of Style (17th edition)