Comparative Studies for the Assessment of the Quality of Near-Real-Time GPS-Derived Atmospheric Parameters

Abstract Accurate and frequent sampling of atmospheric parameters, such as water vapor, is important for enabling reliable weather forecasts and global climate studies over a wide range of spatial and temporal scales. Recent developments in global positioning system data processing have allowed the estimation of zenith total delay (ZTD), the delay of the neutral atmosphere, with a high degree of accuracy using continuously operating GPS networks. From this delay integrated water vapor can be derived by means of additional meteorological information, in particular observed pressure or numerical weather prediction model pressure. Comparisons with other independent techniques must be performed to evaluate the quality of atmospheric parameters directly estimated or retrieved from the GPS system. In this work the accuracy of GPS atmospheric parameter, namely, zenith total delay, delivered in near–real time from a European ground-based network of permanent GPS receivers has been assessed. It is compared to other GPS solutions, radiosonde profiles, and High-Resolution Limited-Area Model (HIRLAM)-derived ZTD. Intercomparisons between results from different GPS analysis centers in the framework of the Targeting Optimal Use of GPS Humidity Measurements in Meteorology (TOUGH) project show a mean ZTD station bias at the level of ±6 mm with a related standard deviation of about 7–8 mm. In the comparison with radiosondes, an overall ZTD bias of about 7 mm with a standard deviation of 9 mm is detected. Finally, the comparison of ZTD near–real time against the HIRLAM models has an average bias of about −4.8 mm and a standard deviation of 11.5 mm

Tidal modulation of plate motions

While mantle convection is a fundamental ingredient of geodynamics, the driving mechanism of plate tectonics remains elusive. Are plates driven only from the thermal cooling of the mantle or are there further astronomical forces acting on them? GPS measurements are now accurate enough that, on long baselines, both secular plate motions and periodic tidal displacements are visible. The now >20 year-long space geodesy record of plate motions allows a more accurate analysis of the contribution of the horizontal component of the body tide in shifting the lithosphere. We review the data and show that lithospheric plates retain a non-zero horizontal component of the solid Earth tidal waves and their speed correlates with tidal harmonics. High-frequency semidiurnal Earth's tides are likely contributing to plate motions, but their residuals are still within the error of the present accuracy of GNSS data. The low-frequency body tides rather show horizontal residuals equal to the relative motion among plates, proving the astronomical input on plate dynamics. Plates move faster with nutation cyclicities of 8.8 and 18.6 years that correlate to lunar apsides migration and nodal precession. The highfrequency body tides are mostly buffered by the high viscosity of the lithosphere and the underlying mantle, whereas low-frequency horizontal tidal oscillations are compatible with the relaxation time of the low-velocity zone and can westerly drag the lithosphere over the asthenospheric mantle. Variable angular velocities among plates are controlled by the viscosity anisotropies in the decoupling layer within the low-velocity zone. Tidal oscillations also correlate with the seismic release

High resolution map of migrants in the EU

This report describes a data set generated from the harmonization and spatial processing of official census statistics collected from National Statistical Institutes in 8 EU Member States (France, Germany, Ireland, Italy, Netherlands, Portugal, Spain and UK). The dataset provides a map at high spatial resolution of the population with migrant background in these Member States. The uniqueness of the data set resides both the high level of spatial resolution (cells of 100 by 100 m) and the large geographical coverage which is including almost 45 thousand local administrative units. From this data set it is possible to calculate indicators of concentration of migrants, diversity and spatial residential segregation which can support comparative research and policies on the local aspect of the integration of migrants in the EU.JRC.E.6-Demography, Migration and Governanc

Anomaly Detection of Mobility Data with Applications to COVID-19 Situational Awareness

This work introduces a live anomaly detection system for high frequency and high-dimensional data collected at regional scale such as Origin Destination Matrices of mobile positioning data. To take into account different granularity in time and space of the data coming from different sources, the system is designed to be simple, yet robust to the data diversity, with the aim of detecting abrupt increase of mobility towards specific regions as well as sudden drops of movements. The methodology is designed to help policymakers or practitioners, and makes it possible to visualise anomalies as well as estimate the effect of COVID-19 related containment or lifting measures in terms of their impact on human mobility as well as spot potential new outbreaks related to large gatherings

Mapping Mobility Functional Areas (MFA) using Mobile Positioning Data to Inform COVID-19 Policies: A European regional analysis

This work introduces the concept of data-driven Mobility Functional Areas (MFAs) as geographic zones with high degree of intra-mobility exchanges. Such information, calculated at European regional scale thanks to mobile data, can be useful to inform targeted reescalation policy responses in cases of future COVID-19 outbreaks (avoiding large-area or even national lockdowns). In such events, the geographic distribution of MFAs would define territorial areas to which lockdown interventions could be limited, with the result of minimising socio-economic consequences of such policies. The analysis of the time evolution of MFAs can also be thought of as a measure of how human mobility changes not only in intensity but also in patterns, providing innovative insights into the impact of mobility containment measures. This work presents a first analysis for 15 European countries (14 EU Member States and Norway).JRC.E.6-Demography, Migration and Governanc

How human mobility explains the initial spread of COVID-19: A European regional analysis

Countries in Europe took different mobility containment measures to curb the spread of COVID-19. The European Commission asked Mobile Network Operators to share on a voluntarily basis anonymised and aggregate mobile data to improve the quality of modelling and forecasting for the pandemic at EU level. In fact, mobility data at EU scale can help understand the dynamics of the pandemic and possibly limit the impact of future waves. Still, since a reliable and consistent method to measure the evolution of contagion at international level is missing, a systematic analysis of the relationship between human mobility and virus spread has never been conducted. A notable exceptions are France and Italy, for which data on excess deaths, an indirect indicator which is generally considered to be less affected by national and regional assumptions, are available at department and municipality level respectively. Using these information together with anonymysed and aggregated mobile data, this study shows that mobility alone can explain up to 92% of the initial spread in these two EU countries, while it has a slow decay effect after lockdown measures, meaning that mobility restrictions seem to have effectively contribute to save lives. It also emerges that internal mobility is more important than mobility across provinces and that the typical lagged positive effect of reduced human mobility on reducing excess deaths is around 14-20 days. An analogous analysis relative to Spain, for which an IgG SARS-Cov-2 antibody screening study at province level is used instead of excess deaths statistics, confirms the findings. The same approach adopted in this study can be easily extended to other European countries, as soon as reliable data on the spreading of the virus at a suitable level of granularity will be available. Looking at past data, relative to the initial phase of the outbreak in EU Member States, this study shows in which extent the spreading of the virus and human mobility are connected. The findings will support policymakers in formulating the best data-driven approaches for coming out of confinement, and mostly in building future scenarios in case of new outbreaks.JRC.E.6-Demography, Migration and Governanc

Measuring the Impact of COVID-19 Confinement Measures on Human Mobility using Mobile Positioning Data: A European regional analysis

This paper presents a mobility indicator derived from anonimised aggregated mobile positioning data. Even though the indicator does not provide information about the behaviour of individuals, it captures valuable insights into the mobility patterns of the population in the EU and it is expected to inform responses against the COVID-19 pandemic. Spatio-temporal harmonisation is carried out so that the indicator can provide mobility estimates comparable across European countries. The indicators are provided at a high spatial granularity (up to NUTS3). As an application, the indicator is used to study the impact of COVID-19 confinement measure on mobility in Europe. It is found that a large proportion of the mobility patterns can be explained by these measures. The paper also presents a comparative analysis between mobility and the infection reproduction number Rt over time.JRC.E.6-Demography, Migration and Governanc