Non-Tidal Ocean Loading Correction for the Argentinean-German Geodetic Observatory Using an Empirical Model of Storm Surge for the Río de la Plata

Abstract

The Argentinean-German Geodetic Observatory is located 13 km from the Rı ´o de la Plata, in an area that is frequently affected by storm surges that can vary the level of the river over ±3 m. Water-level information from seven tide gauge stations located in the Rı ´o de la Plata are used to calculate every hour an empirical model of water heights (tidal ? non-tidal component) and an empirical model of storm surge (non-tidal component) for the period 01/2016-12/2016. Using the SPOTL software, the gravimetric response of the models and the tidal response are calculated, obtaining that for the observatory location, the range of the tidal component (3.6 nm/s 2 ) is only 12% of the range of the non-tidal component (29.4 nm/s 2 ). The gravimetric response of the storm surge model is subtracted from the superconducting gravimeter observations, after applying the traditional corrections, and a reduction of 7% of the RMS is obtained. The wavelet transform is applied to the same series, before and after the nontidal correction, and a clear decrease in the spectral energy in the periods between 2 and 12 days is identify between the series. Using the same software East, North and Up displacements are calculated, and a range of 3, 2, and 11 mm is obtained, respectively. The residuals obtained after applying the non-tidal correction allow to clearly identify the influence of rain events in the superconducting gravimeter observations, indicating the need of the analysis of this, and others, hydrological and geophysical effects.

Hydrometeorological and gravity signals at the Argentine-German Geodetic Observatory (AGGO) in La Plata

“…As shown in Oreiro et al (2018), the effect of non-tidal ocean loading by storm surges plays a very important role in gravity recordings at AGGO. In this study, the corresponding gravity effect was computed using four models with global coverage.…”

“…The proximity to the extremely large estuary plays an important role in observations at AGGO, especially owing to the frequent storm surges. Further details on the characteristics of the estuary and its hydrological regimes can be found in Oreiro et al (2018).…”

“…All sensors are located in the direct vicinity of the gravimeter building as observations by terrestrial gravimetry are known to be most sensitive to mass variations in the near field around the sensors (e.g. Güntner et al, 2017;Reich et al, 2018). Table 1 shows the type and the number of employed hydrological sensors.…”

“…Additionally, the effect was computed by utilizing the OMCT RL06 model in combination with the mGlobe toolbox. The non-tidal loading effect of the Río de La Plata estuary was modelled after Oreiro et al (2018). Like in the case of hydrological and atmospheric effects, the full spatial resolution of all input models was used for the computation.…”

“…Kennedy et al, 2016), floods, and storm surges (e.g. Oreiro et al, 2018). Such processes and events may all have tangible effects and increasing relevance for the inhabitants of the study region, known as Buenos Aires Pampa, given that intense floods causing huge material and some human losses have hit the area more frequently since 1980.…”