Understanding geographical and temporal patterns of seasonal influenza can help strengthen influenza surveillance to early detect epidemics and inform influenza prevention and control programs. We examined variations in spatiotemporal patterns of seasonal influenza in different global regions and explored climatic factors that influence differences in influenza seasonality, through a systematic review of peer-reviewed publications. The literature search was conducted to identify original studies published between January 2005 and November 2016. Studies were selected using predetermined inclusion and exclusion criteria. The primary outcome was influenza cases; additional outcomes included seasonal or temporal patterns of influenza seasonality, study regions (temperate or tropical), and associated climatic factors. Of the 2,160 records identified in the selection process, 36 eligible studies were included. There were significant differences in influenza seasonality in terms of the time of onset, duration, number of peaks, and amplitude of epidemics between temperate and tropical/subtropical regions. Different viral types, cocirculation of influenza viruses, and climatic factors, especially temperature and absolute humidity, contributed to the variations in spatiotemporal patterns of seasonal influenza. The findings reported in this review could inform global surveillance of seasonal influenza and influenza prevention and control measures such as vaccination recommendations for different regions.

We present multipoint remote and in situ observations of interplanetary coronal mass ejection (ICME) structures during the year 2011. The selected ICMEs arrived at Earth on 2011 March 11 and 2011 August 6, and led to geomagnetic storms. Around the launch of these CMEs from the Sun, the coronagraphs onboard STEREO-Aand-B and SOHO enabled the CMEs to be imaged from three longitudinally separated viewpoints. We attempt to identify the in situ plasma and magnetic parameters of the ICME structures at multiple locations, for example at both STEREO spacecraft and also at the ACE/Wind spacecraft near the first Sun–Earth Lagrangian point (L1), to investigate the global configuration, interplanetary propagation, arrival times and geomagnetic response of the ICMEs. The near-Earth identified ICMEs of March 11 and August 6 formed as a result of the interaction of two successive CMEs observed in the inner corona on March 7 (for the March 11 ICME) and on August 3–4 (for the August 6 ICME). Our study suggests that the structures associated with interacting CMEs, possibly as a result of deflection or large sizes, may reach to even larger longitudinally separated locations in the heliosphere. Our multipoint in situ analysis shows that the characteristics of the same shock, propagating in a pre-conditioned medium, may be different at different longitudinal locations in the heliosphere. Similarly, multiple cuts through the same ejecta/complex ejecta, formed as a result of CME–CME interaction, are found to have inhomogeneous properties. The study highlights the difficulties in connecting the local observations of an ICME from a single in situ spacecraft to its global structures.

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It has been established that Coronal Mass Ejections (CMEs) may have significant impact on terrestrial magnetic field and lead to space weather events. In the present study, we selected several CMEs which are associated with filament eruptions on the Sun. We attempt to identify the presence of filament material within ICME at 1AU. We discuss how different ICMEs associated with filaments lead to moderate or major geomagnetic activity on their arrival at the Earth. Our study also highlights the difficulties in identifying the filament material at 1AU within isolated and in interacting CMEs.