Abstract
Studying the spatiotemporal distribution and motion of water vapour (WV), the most variable greenhouse gas in the troposphere, is pivotal, not only for meteorology and climatology, but for geodesy, too. In fact, WV variability degrades, in an unpredictable way, almost all geodetic observation based on the propagation of electromagnetic signal through the atmosphere. We use data collected on a dense GPS network, designed for the purposes of monitoring the active Neapolitan (Italy) volcanoes, to retrieve the tropospheric delay parameters and precipitable water vapour (PWV). This study has two main targets: (a) the analysis of long datasets (11 years) to extract trends of climatological meaning for the region; (b) studying the main features of the time evolution of the PWV during heavy raining events to gain knowledge on the preparatory stages of highly impacting thunderstorms. For the latter target, both differential and precise point positioning (PPP) techniques are used, and the results are compared and critically discussed. An increasing trend, amounting to about 2 mm/decades, has been recognized in the PWV time series, which is in agreement with the results achieved in previous studies for the Mediterranean area. A clear topographic effect is detected for the Vesuvius volcano sector of the network and a linear relationship between PWV and altitude is quantitatively assessed. This signature must be taken into account in any modelling for the atmospheric correction of geodetic and remote-sensing data (e.g., InSAR). Characteristic temporal evolutions were recognized in the PWV in the targeted thunderstorms (which occurred in 2019 and 2020), i.e., a sharp increase a few hours before the main rain event, followed by a rapid decrease when the thunderstorm vanished. Accounting for such a peculiar trend in the PWV could be useful for setting up possible early warning systems for those areas prone to flash flooding, thus potentially providing a tool for disaster risk reduction.
Highlights
Licensee MDPI, Basel, Switzerland.Climate change presents a threat to human societies
For the second and third datasets, we focused on the city of Napoli to investigate how global navigation satellite system (GNSS)-derived parameters can contribute to understanding the spatiotemporal evolution of three major thunderstorm/heavy rain events that hit the Neapolitan area during 2019 and 2020
Tropospheric water vapour content is a crucially important meteorological parameter because, besides being one of the main greenhouse gases, it is involved in the energy
Summary
Licensee MDPI, Basel, Switzerland.Climate change presents a threat to human societies. To what extent is today’s regional and global water and energy cycles’ change due to natural variability versus anthropogenic influences?. TWS and tropospheric water are key variables of the Earth’s climate, impacting both surface water and atmospheric energy budgets. These satellite observations are providing a breakthrough for studying the global water cycle under current and future climate conditions [5]
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