Michal Kozubek

Long-term trends in the total electron content

The total electron content (TEC) is important among others for Global Navigation Satellite Systems/GPS signal propagation and applications. However, there is only one comprehensive analysis of TEC trends, and the resulted trends are not consistent with trends in other ionospheric parameters. Here we use the TEC data of Lean et al. (2011) and the JPL35 homogeneous TEC data series derived by Emmert et al. (2017). This analysis results in three main conclusions: (1) Too positive TEC trends by Lean et al. (2011) are caused by data problems in 1995–2001, particularly by too low Center for Orbit Determination data. (2) TEC reveals a weak negative trend at the edge of reliability; no trend or trend break is also possible; longer data series than 1994–2015 is required. (3) About 99% of the total variance of yearly average global TEC values is explained by variability of solar activity.

Advancing Global & Regional Reanalyses

This report outlines the structure of and summarizes the recommendations made at the 5th International Conference on Reanalysis (ICR5), attended by 259 participants from 37 countries, in Rome (Italy), on 13-17 November 2017. It first summarizes the conference structure. Then, the key recommendations of ICR5 are given for the five main conference topics: production; observations (data rescue and preparation); data assimilation methods; quality assurance of reanalysis; and applications in science, services, and policymaking. Lastly, five high-level recommendations are proposed to managing agencies on how best to advance the field of reanalyses, which serves tens of thousands of users, via enhanced research, development, and operations.