Multi-year GNSS monitoring of atmospheric IWV over Central and South America for climate studies

L. MENDOZA; C. BIANCHI; L. FERNÁNDEZ; P. NATALI; A. MEZA; J. MOIRANO

Viena

Congreso; EGU General Assembly 2017; 2017

European Geosciences Union

Atmospheric water vapour has been acknowledged as an essential climate variable. Weather prediction and hazardassessment systems benefit from real-time observations, whereas long-term records contribute to climate studies.Nowadays, ground-based GNSS products have become widely employed, complementing satellite observationsover the oceans. Although the past decade has seen a significant development of the GNSS infrastructure inCentral and South America, its potential for atmospheric water vapour monitoring has not been fully exploited.With this in mind, we have performed a regional, seven-year long and homogeneous analysis, comprising136 GNSS tracking stations, obtaining high-rate and continuous observations of column integrated water vapourand troposphere zenith total delay (Bianchi et al. 2016). As preliminary application for this data set, we haveestimated 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, whilea 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 tropospheredelays. The model fairly reproduces the observed mean delays, including their annual and semi-annual variations.Nevertheless, a long-term evaluation has shown systematical biases, up to 20 mm, probably inherited form theunderling atmospheric reanalysis.Additionally, the complete data set has been made openly available at a scientific repository(doi:10.1594/PANGAEA.858234).