Sea Level Fusion of Satellite Altimetry and Tide Gauge Data by Deep Learning in the Mediterranean Sea

Satellite altimetry and tide gauges are the two main techniques used to measure sea level. Due to the limitations of satellite altimetry, a high-quality unified sea level model from coast to open ocean has traditionally been difficult to achieve. This study proposes a fusion approach of altimetry and tide gauge data based on a deep belief network (DBN) method. Taking the Mediterranean Sea as the case study area, a progressive three-step experiment was designed to compare the fused sea level anomalies from the DBN method with those from the inverse distance weighted (IDW) method, the kriging (KRG) method and the curvature continuous splines in tension (CCS) method for different cases. The results show that the fusion precision varies with the methods and the input measurements. The precision of the DBN method is better than that of the other three methods in most schemes and is reduced by approximately 20% when the limited altimetry along-track data and in-situ tide gauge data are used. In addition, the distribution of satellite altimetry data and tide gauge data has a large effect on the other three methods but less impact on the DBN model. Furthermore, the sea level anomalies in the Mediterranean Sea with a spatial resolution of 0.25° × 0.25° generated by the DBN model contain more spatial distribution information than others, which means the DBN can be applied as a more feasible and robust way to fuse these two kinds of sea levels.

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Coastal sea level trends from TOPEX-Poseidon satellite altimetry and tide gauge data in the Mediterranean Sea during the 1990s

Geophysical Journal International ◽

10.1111/j.1365-246x.2007.03424.x ◽

2007 ◽

Vol 170 (1) ◽

pp. 132-144 ◽

Cited By ~ 10

Author(s):

S. Mangiarotti

Keyword(s):

Mediterranean Sea ◽

Sea Level ◽

Satellite Altimetry ◽

Tide Gauge ◽

Tide Gauge Data ◽

Gauge Data ◽

Coastal Sea ◽

The Mediterranean

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Multi-decadal sea level trends and land movements in the Mediterranean Sea with estimates of factors perturbing tide gauge data and cumulative uncertainties

Global and Planetary Change ◽

10.1016/j.gloplacha.2010.12.002 ◽

2011 ◽

Vol 76 (1-2) ◽

pp. 63-76 ◽

Cited By ~ 34

Author(s):

M. Tsimplis ◽

G. Spada ◽

M. Marcos ◽

N. Flemming

Keyword(s):

Mediterranean Sea ◽

Sea Level ◽

Tide Gauge ◽

Tide Gauge Data ◽

Gauge Data ◽

The Mediterranean

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More confounders at global and decadal scales in detecting recent sea level accelerations

Journal of Geodetic Science ◽

10.1515/jogs-2015-0020 ◽

2015 ◽

Vol 5 (1) ◽

Author(s):

H. Bâki Iz

Keyword(s):

Sea Level ◽

Satellite Altimetry ◽

Tide Gauge ◽

Almost Periodic ◽

Altimetry Data ◽

Tide Gauge Data ◽

Gauge Data ◽

Close Range ◽

Globally Distributed ◽

Satellite Altimetry Data

AbstractThe residuals of 27 globally distributed long tide gauge recordswere scrutinized after removing the globally compounding effect of the periodic lunar node tides and almost periodic solar radiation’s sub and superharmonics from the tide gauge data. The spectral analysis of the residuals revealed additional unmodeled periodicities at decadal scales, 19 of which are within the close range of 12–14 years, at 27 tide gauge stations. The amplitudes of the periodicitieswere subsequently estimated for the spectrally detected periods and they were found to be statistically significant (p «0.05) for 18 out of 27 globally distributed tide gauge stations. It was shown that the estimated amplitudes at different localities may have biased the outcome of all the previous studies based on tide gauge or satellite altimetry data that did not account for these periodicities, within the range −0.5 – 0.5 mm/yr., acting as another confounder in detecting 21st century sea level rise.

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Complex Extreme Sea Levels Prediction Analysis: Karachi Coast Case Study

Entropy ◽

10.3390/e22050549 ◽

2020 ◽

Vol 22 (5) ◽

pp. 549

Author(s):

Faisal Ahmed Khan ◽

Tariq Masood Ali Khan ◽

Ali Najah Ahmed ◽

Haitham Abdulmohsin Afan ◽

Mohsen Sherif ◽

...

Keyword(s):

Water Level ◽

Sea Level ◽

Tide Gauge ◽

Probability Method ◽

Annual Maximum ◽

Tide Gauge Data ◽

Sea Levels ◽

Extreme Sea Levels ◽

Gauge Data ◽

Pakistan Coast

In this study, the analysis of the extreme sea level was carried out by using 10 years (2007–2016) of hourly tide gauge data of Karachi port station along the Pakistan coast. Observations revealed that the magnitudes of the tides usually exceeded the storm surges at this station. The main observation for this duration and the subsequent analysis showed that in June 2007 a tropical Cyclone “Yemyin” hit the Pakistan coast. The joint probability method (JPM) and the annual maximum method (AMM) were used for statistical analysis to find out the return periods of different extreme sea levels. According to the achieved results, the AMM and JPM methods erre compatible with each other for the Karachi coast and remained well within the range of 95% confidence. For the JPM method, the highest astronomical tide (HAT) of the Karachi coast was considered as the threshold and the sea levels above it were considered extreme sea levels. The 10 annual observed sea level maxima, in the recent past, showed an increasing trend for extreme sea levels. In the study period, the increment rates of 3.6 mm/year and 2.1 mm/year were observed for mean sea level and extreme sea level, respectively, along the Karachi coast. Tidal analysis, for the Karachi tide gauge data, showed less dependency of the extreme sea levels on the non-tidal residuals. By applying the Merrifield criteria of mean annual maximum water level ratio, it was found that the Karachi coast was tidally dominated and the non-tidal residual contribution was just 10%. The examination of the highest water level event (13 June 2014) during the study period, further favored the tidal dominance as compared to the non-tidal component along the Karachi coast.

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Analysis of sea level rise and tidal components based on satellite altimetry Jason-2 and tide gauge data in 2008-2016 in Sunda Kelapa

Journal of Physics Conference Series ◽

10.1088/1742-6596/1153/1/012016 ◽

2019 ◽

Vol 1153 ◽

pp. 012016

Author(s):

Sorja Koesuma ◽

Ariyanti ◽

Budi Legowo

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Satellite Altimetry ◽

Tide Gauge ◽

Tide Gauge Data ◽

Gauge Data

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Sea level accelerations at globally distributed tide gauge stations during the satellite altimetry era

Journal of Geodetic Science ◽

10.1515/jogs-2018-0013 ◽

2018 ◽

Vol 8 (1) ◽

pp. 130-135 ◽

Cited By ~ 1

Author(s):

H. Bâki Iz ◽

C. K. Shum ◽

C. Y. Kuo

Keyword(s):

Sea Level ◽

Satellite Altimetry ◽

Tide Gauge ◽

Tide Gauge Data ◽

Trend Model ◽

Gauge Data ◽

Sea Level Variations ◽

Global Mean Sea Level ◽

Globally Distributed ◽

Global Mean

Abstract This observational study reports that several globally distributed tide gauge stations exhibit a propensity of statistically significant sea level accelerations during the satellite altimetry era. However, the magnitudes of the estimated tide gauge accelerations during this period are systematically and noticeably smaller than the global mean sea level acceleration reported by recent analyses of satellite altimetry. The differences are likely to be caused by the interannual, decadal and interdecadal sea level variations, which are modeled using a broken trend model with overlapping harmonics in the analyses of tide gauge data but omitted in the analysis of satellite altimetry.

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