Sea‐level trends and interannual variability in the Caribbean Sea

Abstract

[1] Sea-level trends and their forcing have been investigated in the Caribbean Sea using altimetry and tide gauge time series from 19 stations. The basin average sea-level rise is 1.7 6 1.3 mm yr À1 for the period 1993-2010. Significant spatial variability of the trends is found. The steric variability above 800 m combined with the global isostatic adjustment explains the observed trends for the altimetry period in most of the basin. Wind forcing changes causes the trends in the southern part of the basin, modulating the sea level through changes in the ocean circulation. The longest time series (102 years) of Cristobal shows a trend of 1.9 6 0.1 mm yr À1 insignificantly different from the global mean sea-level rise for the twentieth century. By contrast Cartagena, a world heritage site, has a large trend (5.3 6 0.3 mm yr À1 ) significantly affected by local vertical land movements. Stations dominated by the steric contribution have smaller trends ($1.3 6 0.2 mm yr À1 ). Sea-level trends at tide gauges are not affected by atmospheric pressure changes or by the open ocean steric contribution at most stations. Decadal variability in the sea-level trends can partly be explained by steric and wind variability. The decadal variability in the trends is not spatially coherent. Interannual sea-level variability accounts for one third of the total sea-level variability and can be partly explained by the influence of El Niño-Southern Oscillation at different time and spatial scales. No correlation with the North Atlantic Oscillation is found.

Sea level extremes in the Caribbean Sea

“…Trends are computed from the available record at each station. Linear sea level trends of the 50th percentile vary between 1.3 6 0.5 mm yr 21 in Magueyes and 8.5 6 1.3 mm yr 21 in P. Cortes (Table 3), and in all cases are insignificantly different from the mean sea level trends found by Torres and Tsimplis [2013]. Differences in the trends among the stations are due to the different time periods covered by the records (Figure 1b) and the large spatial and temporal variability in the Caribbean mean sea level trends [Torres and Tsimplis, 2013].…”

“…Negative correlation between the ENSO index and the cyclone activity was reported by Klotzbach [2010]. Torres and Tsimplis [2013] found a positive correlation between interannual sea level variability and ENSO with a time lag of 3 months. Thus, a positive phase of ENSO seems to be related to an increase in the mean sea level but to a decrease in the extremes at two of the stations assessed in the Caribbean Sea.…”

“…Sea level extremes (99.9th percentile) have increased during the last century in the five stations with long records by a rate between 1.5 6 1.0 mm yr 21 in Magueyes (44 years) to 9.9 6 2.2 mm yr 21 in P. Cortes (21 years; Table 3). Increases in the extremes are consistent with the mean sea level trend at each station, thus at least 40 years of data [Torres and Tsimplis, 2013] are needed to obtain temporally stable trends in the extremes. In Cartagena (43 years) the sea level extremes secular trend is 5.8 6 0.8 mm yr 21 (Table 3); thus in a century, the maximum observed sea level extreme (46 cm in Figure 2b) can double its height as consequence of mean sea level rise alone.…”

“…Haigh et al [2010] found that this is the most appropriate method to handle the trends to estimate return levels at sites with less than 50 years of data in the English Channel. This approach seems to be reasonable for the Caribbean Sea, as Torres and Tsimplis [2013] showed that at least 40 years of data are needed in order to obtain stable coastal mean sea level trends in the region; thus, sea level return periods computed form shorter periods will be affected by trends' temporal variability. In the Caribbean, only Cristobal has records longer than 50 years ( Table 1).…”

“…This is partly due to the different periods for which observations exist ( Figure 1b). The existence of significant mean sea level trends, with large spatial and temporal variability in the Caribbean [Torres and Tsimplis, 2013], is expected to influence the spatial comparison of the observed extremes especially because the record span varies between 5 years in Le Robert and 103 years in Cristobal (Table 1).…”