Comparison of global and regional tide models using data from satellite altimeters and tide gauges in the Northeast Sector of the Antarctic Peninsula

FERNANDO OREIRO; MONICA FIORE; WALTER GRISMEYER; MARTIN SARACENO

Venice

Simposio; 20 years of Progress in Radar Altimetry symposium; 2012

A number of global and regional tide models have been developed and improved in the last decade with the purpose of obtaining the best correction to be applied to the satellite heights. It has been shown that these models are less accurate in coastal and polar areas, as Antarctica, than in other ocean areas. An accurate knowledge of the tides in Antarctica is difficult because of the limited number and short duration of the tide gauge observations. However, since few years ago the number of altimetry observations in Antarctica is enough to get precise components of tide, especially in the Northeast Sector of the Antarctic Peninsula. This area is characterized by the presence of iceberg and rubble ice broken off from glaciers and Ronne-Filchner and Larsen ice shelves. In addition to this, parts of polar ocean are covered by permanent or seasonal sea ice. These conditions limit the number of useful satellite altimetry data considerably. In this work, a comparison of the latest global and regional tide models with available tide-gauge and altimetry data is performed in the Northeast Sector of the Antarctic Peninsula. Observations of tide gauges are scarce, due to the fact that most of the Antarctic bases are located on the west coast of the Antarctic Peninsula and on the South Shetland Islands. For the chosen area a comparative analysis between the amplitudes and epochs of 8 components of tide (Q1, O1, P1, K1, N2, M2, S2, and K2) obtained from 44 intersections of T/P, Jason1 and Jason2 tracks and 3 conventional tide gauges versus 9 tide models: GOT4.7 [1], TPXO7.2 [2], FES2004 [3], EOT08a [4], EOT10a [5], AOATLAS2011 [6], ANTPEN04.01 [7], CATS2008 (CATS2008; Padman, pers. comm.) and CADA10 [8] is performed. Results show that for the most important semidiurnal constituent M2, the smallest Root Mean Square misfits (RMS misfit) correspond to models EOT08a, CADA10 and EOT10a (1.9cm, 2.0cm and 2.1cm respectively). For the most important diurnal constituent O1 the smallest RMS misfit corresponds to TPXO7.2 (2.5cm). The highest Root Sum Square (RSS) obtained from the RMS misfits of the 8 constituents is obtained by CATS2008 (18.9cm), while the rest of the models have a similar performance (lower than 8.8cm). The lowest RSS corresponds to the models EOT10a, ANTPEN04.01, EOT08a and TPXO7.2 (5.8cm, 5.9cm, 6.0cm and 6.1cm respectively). To analyze the individual performance of the models in the 47 selected locations, the RSS is calculated for each one. The analysis of the results shows that the errors are greater south of 63°S and in the proximity of the 3 coastal tide gauges. This is probably due to the small quantity of altimetry data corresponding to the south of the study area and that not all models assimilate data from tide gauge.