We compared 2 years of wind measurements by the Aeolus satellite with winds from two wind-profiler radars in Arctic Sweden and coastal Antarctica. Biases are similar in magnitude to results from other locations. They are smaller than in earlier studies due to more comparison points and improved criteria for data rejection. On the other hand, the standard deviation is somewhat higher because of degradation of the Aeolus lidar.

Wind measurements from two radars (ESRAD in Arctic Sweden and MARA at the Indian Antarctic station Maitri) are compared with lidar winds from the ESA satellite Aeolus, for July–December 2019. The aim is to check if Aeolus data processing is adequate for the sunlit conditions of polar summer. Agreement is generally good with bias in Aeolus winds < 1 m/s in most circumstances. The exception is a large bias (7 m/s) when the satellite has crossed a sunlit Antarctic ice cap before passing MARA.

We validate horizontal wind measurements at altitudes of 0.5–14 km made with atmospheric radars: ESRAD located near Kiruna in the Swedish Arctic and MARA at the Indian research station Maitri in Antarctica, by comparison with radiosondes, the regional model HARMONIE-AROME and the ECMWF ERA5 reanalysis. Good agreement was found in general, and radar bias and uncertainty were estimated. These radars are planned to be used for validation of winds measured by lidar by the ESA satellite Aeolus.

In December 1991, precipitation on the Glorieuses and Mayotte was more than 3 times the climatological mean and mean sunshine duration was less than 1.5h per day. The most likely explanation was low values of the Madden-Julian Oscillation index, which favours high rainfall. El Niño, eastward quasi-biennial oscillation and high solar activity may also have had an indirect effect. No effect of the Pinatubo volcanic eruption is indicated as the precipitation anomalies are only local.

High-speed streams of particles from the Sun can cause high-energy electrons to be precipitated into the Earth's middle atmosphere at polar latitudes. The paper develops and tests a model for how these particles can change the amount of a trace gas, nitric oxide, which has the potential to destroy stratospheric ozone. Model calculations agree well with observations by the Odin satellite of increased nitric oxide over Antarctica associated with high-speed solar wind streams.