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S U M M A R YThe present-day deformation of the earth crust in the Argentine part of Tierra del Fuego main island (southernmost South America) is here investigated based on repeated geodetic GPS observations. The island is traversed by the active transform boundary between the South American and Scotia tectonic plates, represented by the Magallanes-Fagnano fault system. Since 1993 a regional network comprising to date 29 GPS sites has been observed almost every year. The complete set of accumulated observations was processed using the Bernese GPS software and state-of-the-art processing strategies and models. The utilization of homogeneous GPS products resulting from a reprocessing of the global IGS network warrants a stable realization of a global reference frame. For each GPS site 3-D positions and linear velocities with error estimates were obtained. A strain analysis of the horizontal velocity components revealed the zones of major deformation activity. A 30-km-wide deformation belt centred on the main trace of the fault system was identified. This belt is bordered to the north (South America) and south (Scotia) by geodynamically stable zones, which move horizontally with a relative average velocity of 4.4 ± 0.6 (east) and −0.3 ± 0.4 (north) mm a −1 . Within the deformation belt a maximum strain rate in the order of 0.25 μstrain per year has been detected. A pronounced change in the deformation style from transtension (east) to transpression (west) is observed. The area of predominating shortening of the crust coincides with a local rotation minimum and relative uplift. Throughout the period covered by the GPS observations the displacements and deformations occurred to be linear with time.

Abstract. Atmospheric water vapour has been acknowledged as an essential climate variable. Weather prediction and hazard assessment systems benefit from real-time observations, whereas long-term records contribute to climate studies. Nowadays, ground-based global navigation satellite system (GNSS) products have become widely employed, complementing satellite observations over the oceans. Although the past decade has seen a significant development of the GNSS infrastructure in Central and South America, its potential for atmospheric water vapour monitoring has not been fully exploited. With this in mind, we have performed a regional, 7-year-long and homogeneous analysis, comprising 136 GNSS tracking stations, obtaining high-rate and continuous observations of column-integrated water vapour and troposphere zenith total delay. As a preliminary application for this data set, we have estimated local water vapour trends, their significance, and their relation with specific climate regimes. We have found evidence of drying at temperate regions in South America, at a rate of about 2 % per decade, while a slow moistening of the troposphere over tropical regions is also weakly suggested by our results. Furthermore, we have assessed the regional performance of the empirical model GPT2w to blindly estimate troposphere delays. The model reproduces the observed mean delays fairly well, including their annual and semi-annual variations. Nevertheless, a long-term evaluation has shown systematical biases, up to 20 mm, probably inherited from the underlying atmospheric reanalysis. Additionally, the complete data set has been made openly available as supplementary material.

[1] We demonstrate the application of a 100 km long lake as a sensor for studying the tidal effects on Tierra del Fuego main island. The lake-level variations observed in Lago Fagnano reflect both the direct response to the tidal potential and the indirect effect of the ocean tidal loading. Modeling both contributions explains the observed tidal signal in the lake to about 70%. Underestimated model load tide amplitudes are found to be probably responsible for the remaining difference. We interpret this discrepancy as a hint for regional elastic lithosphere properties differing substantially from those represented by currently available global models.

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Taking advantage of the public Global Navigational Satellite Systems (GNSS) infrastructure in South America, an operational monitoring system for the total electron content (TEC) in the ionosphere has been developed. It incorporates data in near real time, from more than 90 GNSS satellites tracked by more than 200 ground stations. In turn, the system produces every 15 min a snapshot, that is a map, of the current state of the regional ionosphere, which is immediately available online. These maps could be employed, for example, to augment positioning with single‐frequency GNSS receivers. They could also be combined with similar products in order to obtain weighted and reliable regional TEC maps, even in near real time. Most importantly, these products could be employed as data input in space environment forecasting and nowcasting models, given their very short latency of just a few minutes. In order to assess the response of the whole system to severe geomagnetic disturbances, the performance of the whole monitoring system during an actual geomagnetic storm has been investigated. The results suggest that the near‐real‐time system should be quite capable to monitor the regional TEC at a high temporal rate even under such conditions.

Development of regional services able to provide ionospheric total electron content (TEC) maps with a high spatial resolution, and in near real-time, are of high importance for applications and the research community. We provide here the methodologies, and a preliminary assessment, of such a system.The system relies on the public Global Navigational Satellite Systems (GNSS) infrastructure in South America, it incorporates data from multiple constellations (currently GPS, GLONASS, Galileo and BeiDou), it employs multiple frequencies, and it produces continental wide TEC maps with a latency of just few minutes. A year-round comparison of the produced maps with several products issued by the International GNSS Service (IGS) resulted in mean biases lower than 1 TEC units (TECU), whereas their evaluation against direct and independent GNSS-based slant TEC measurements resulted in accuracies of the same magnitude.