Both the day-to-day analysis and superposed epoch analysis of the noctilucent cloud (NLC) data revealed conspicuous correlations between NLCs and the solar wind magnetic fields, in both polar regions. The responses in the Southern Hemisphere and Northern Hemisphere are opposite, and the lag time is fairly short. These two features are beyond the explanations of previously proposed solar photodissociation origin or dynamic origin for the solar–NLC link, and a possible new mechanism is discussed.

Using the Met Office NAME dispersion model, supported by satellite- and ground-based remote-sensing observations, we describe the dispersion of aerosols from the 2019 Raikoke eruption and the concurrent wildfires in Alberta Canada. We show how the synergy of dispersion modelling and multiple observation sources allowed observers in the London VAAC to arrive at a more complete picture of the aerosol loading at altitudes commonly used by aviation.

Ice particles of noctilucent clouds (NLCs) are used as a tracer to investigate tidal signatures in the altitude range from 80 to 90 km. For the first time solar and lunar tidal parameters in NLCs were determined simultaneously from the same data set. Solar variations are dominated by diurnal and semidiurnal tidal components. For NLC occurrence the lunar semidiurnal amplitude is approx. 50 % of the solar semidiurnal amplitude. Phases of solar components indicate upward propagating tides.

We have analysed IR measurements of PMCs in the NH and SH from 2005 to 2012. This technique is sensitive to the total ice volume independent of particle size. For the first time, we have measured the total ice volume from the midlatitudes to the poles. The data indicate a layer of ice from 81 to 89 km and from the poles to 50–60º in each hemisphere, increasing near the poles. The ice density is larger in the NH than in the SH and located 1 km lower. PMCs also show a diurnal variation.