Abstract

TAPIA FLORES, K. M.; UTRERA ZARATE, A.  and  TEJEDA MARTINEZ, A.. Analysis of Trends in Sea Level in the Central Coast of the Gulf of Mexico, 1999-2018. Invest. Geog [online]. 2022, n.108, e60525.  Epub Sep 12, 2022. ISSN 2448-7279.  https://doi.org/10.14350/rig.60525.

There is scientific consensus about a 0.20-meter rise in the global mean sea level over the period 1901-2018 (IPCC, 2021). This is a global figure, but the phenomenon is not occurring evenly throughout the world, so studies at smaller scales are relevant. This article describes the quantitative analysis performed to determine the current and future sea-level behavior on the central coast of the Gulf of Mexico and determine whether or not it shows a rise similar to the one reported on a global scale. The aim was to determine the sea level trend observed in the region.

Based on the methodological approach of Zavala-Hidalgo et al. (2011), we selected three stations belonging to Mexico’s National Mareographic Network to characterize the sea level on the central coast of the Gulf of Mexico: Coatzacoalcos (18°09’ N, -94°26’ W); Frontera (18°32’ N, -92°38’ W), and Veracruz (19°12’ N, -96°08’ W). Daily and annual cycles were plotted to determine the current behavior of the sea level. Subsequently, using hourly records, graphs of the temporal evolution of tides were constructed for the years available in each time series. Each of these graphs was associated with a trend line describing the sea-level variations over time, and a numerical value for each trend line was calculated along with its associated uncertainty. Finally, we estimated future values for sea-level height in the region using extrapolations. These predictions were compared with other databases for the qualitative analysis.

The first results obtained indicate a stable and constant behavior of sea level on the central coast of the Gulf of Mexico, with well-defined daily and annual cycles. The overall sea-level trend in this region is -1.86 mm year-1 from 1999 to 2018. The general trend in the first decade was +3.6 mm year-1 and in the second, -1.26 mm year-1. In the period 2000 to 2010, the mean sea level on the central coast of the Gulf of Mexico rose by about 0.03 meters. The period 2011 to 2018 shows a reduction in sea level of approximately 0.008 meters. Predictions constructed with extrapolations estimated a future rise of about 0.47 to 1.07 meters by 2200 considering the trend observed in the first decade and a reduction of 0.41 to 0.02 meters by 2200 considering the trend in the second decade.

The overall trend observed in the period 1999-2018 for the central coast of the Gulf of Mexico corresponds to a decrease in sea level in the region, but its effects have not been observed. The first decade of the period considered shows a constant rise in sea level until 2010. From 2011, the increase was slower and more progressive. The corrected segmented trend for the first decade is consistent with the global average trend established by the IPCC (2021). The negative trends do not coincide with any values reported in the literature. Our sea-level projections underestimate the rise compared to those associated with RCPs 2.6, 4.5, and 8.5.

Two of the three mareographic stations considered in the present study did not record data over a full year (2011) and resumed reporting data with values lower than those at the start of the suspension. The nature of this gap in the time series was not determined in the present study, but it may be associated with instrument recalibration. The effect of this recording suspension on the results presented is unknown, although a potential causal relationship is not ruled out.

Keywords : sea level height; Gulf of Mexico; sea-level trends; tidal cycles; sea-level predictions.

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