I agree with the handling aditor that this is a very useful and comprehensive study and deserves wide attention.

I fully support the justification given by the handling editor

Atmospheric rivers (ARs) are recognized as significant contributors to extreme precipitation at mid-latitudes and may increase in frequency and intensity due to climate change. This timely study is the first the show the potential value of GNSS radio occultation (GNSS RO) remote sensing to the study of ARs and in particular how the high vertical resolution of GNSS RO provides information that is complementary to other techniques. The combination of GNSS-RO data with mesoscale models, particularly through assimilation, could further improve our understanding of AR dynamics and the processes leading to extreme precipitation and flooding. This is an important direction for future studies.

The manuscript presents an approach for enabling direct flux measurements of greenhouse gases to already existing tall tower networks by simply adding a 3D sonic anemometer to each station. This way, the spatial information density about the land surface exchange and quantifying temporal sources and sinks of greenhouse gases would be significantly improved with little extra instrumental effort. Slower-response analyzers may be used for flux measurements as the relevant frequency ranges at tall towers differ from those closer to the land surface. Tall tower measurements have larger footprints than classical eddy-covariance ecosystem sites, which further amplify spatial coverage of observations. Still, detailed knowledge of surrounding footprints is needed. The presented concept is of high relevance within the scientific greenhouse gas community and may act as a blueprint for bridging scales between atmospheric and ecosystem networks.

Accurate atmospheric measurements of ice nucleating particles (INPs) are needed for improving understanding of their role in affecting cloud properties and climate. Prior international workshops on comparing INP measuring systems were conducted mainly in the laboratory, where high concentrations of INPs were typically employed. This workshop established a template for the conduct of comparisons in an atmospheric setting where low number concentrations of INPs typically exist, representing a very small fraction of all particles. Overall, this study stimulates advances of important but challenging INP measurements and strengthens confidence in their use to understand ice formation in clouds.

Laitinen et al. demonstrate the remarkable agreement between two independent greenhouse gas observation systems (GAW and ICOS) at the Pallas station in Finnish Lapland, confirming the high accuracy and reliability of long-term CO₂ and CH₄ measurements in the Northern Hemisphere. Their results strengthen confidence in atmospheric monitoring data critical for carbon cycle research.

Low-cost sensors have been increasing used to measure air pollutants in environmental epidemiology. This work investigated the calibration and performance evaluation of PM2.5 and NO2 sensors, and introduced novel methodologies for field sensor validation during deployment. The manuscript is thorough and systematic in data treatment, and could be used a best practice guide for the application of sensors to air pollution and epidemiological studies.