Validation of altimeter-derived sea level seasonal cycle with tide gauges over the Gulf of Mexico
Event: 2015 Ocean Surface Topography Science Team Meeting
Session: Regional and Global CAL/VAL for Assembling a Climate Data Record
Presentation type: Type Oral
Global gridded AVISO satellite altimetry data of mean sea level is compared and validated against the monthly tide gauge data from the Permanent Service for Mean Sea Level (PSMSL), UK, over the Gulf of Mexico. Here, we discuss the AVISO altimetry data, assessing the accuracy via comparison with in situ tide gauge data. Anomalies of mean sea level at a number of stations along the coastline of the Gulf of Mexico are investigated. Analysis shows close agreement between the tide gauge and altimeter annual cycle components of the sea level anomalies most of the time and confirms a steady increase in annual amplitude for chosen stations in most recent years (similar to recent work by Wahl and colleagues). In order to address differences between the coast and open sea level variations observed in the altimeter data, annual amplitude for a full time period of 1993-2013 is computed over the Gulf of Mexico region. In particular, temporal variability of regional annual amplitude shows a significant increase in the latest period (2007-2013) over most of the Gulf of Mexico region, especially over the north-eastern coastline waters in the Gulf of Mexico from 10 cm to 14 cm, and even larger in the central part (up to 5-6 cm). Part of this increase appears to be due to changes in atmospheric pressure, acting through the inverted barometer response of the sea level. Similarly as for the Gulf of Mexico, global annual amplitude of the mean sea level anomalies for the same time period confirms a noticeable increase in the recent years for most of the regions, especially over those areas with the annual amplitude that initially experiences higher values (i.e., between 12-20 cm).