Microwave radiometers have the capability of observing temperature and humidity profiles with a few minute time resolution. This study investigates the potential benefit of this instrument to improve weather forecasts thanks to a better initialization of the model. Our results show that a significant improvement can be expected in the model initialization in the first 3 km with potential impacts on weather forecasts.

Choices and assumptions made to represent the state of the atmosphere introduce an uncertainty of 42% to the air mass factor calculation in trace gas satellite retrievals in polluted regions. The AMF strongly depends on the choice of a priori trace gas profile, surface albedo data set and the correction method to account for clouds and aerosols. We call for well-designed validation exercises focusing on situations when AMF structural uncertainty has the highest impact on satellite retrievals.

HNO₃ concentrations are obtained from the IASI instrument and the data set is characterized for the first time in terms of vertical profiles, averaging kernels and error profiles. A validation is also conducted through a comparison with ground-based FTIR measurements, with good results. The data set is then used to analyse HNO3 spatial and temporal variability for the year 2011. The latitudinal gradient and the large seasonal variability in polar regions are well represented with IASI data.

Surface-based two-filter radon detectors monitor the ambient concentration of atmospheric radon-222, a natural tracer of mixing and transport. They are sensitive, but respond slowly to ambient changes in radon concentration. In this paper, a deconvolution method is used to successfully correct observations for the instrument response. Case studies demonstrate that it is beneficial, sometimes necessary, to account for the detector response, especially when studying near-surface mixing.

New radiosonde instruments for humidity-, radiation- and gas profile measurements were introduced in recent years, for atmospheric research and climate monitoring. Such instruments are intended to be reused on multiple flights. Here we introduce the return glider radiosonde (RGR), which enables flying and retrieving valuable in situ upper-air instruments. The RGR is lifted with weather balloons to a preset altitude, and a built-in autopilot flies the glider autonomously back to the launch site.