The accuracy of trace gas retrievals from spaceborne observations, like those from the Orbiting Carbon Observatory 2 (OCO-2), are sensitive to the referenced digital elevation model (DEM). Therefore, we evaluate several global DEMs, used in versions 10 and 11 of the OCO-2 retrieval along with the Copernicus DEM. We explore the impacts of changing the DEM on biases in OCO-2-retrieved X_CO2 and inferred CO₂ fluxes. Our findings led to an update to OCO-2 v11.1 using the Copernicus DEM globally.

The achieved results revealed that the ACDL observations were in good agreement with the ground-based lidar measurements during dust events. The heights of cloud top and bottom from these two measurements were well matched and comparable. This study proves that the ACDL provides reliable observations of aerosol and cloud in the presence of various climatic conditions, which helps to further evaluate the impacts of aerosol on climate and the environment, as well as on the ecosystem in the future.

In this work, we introduce the 2D RGB polarization-resolving cameras of the airborne hyperspectral and polarized imaging system specMACS. A full characterization and calibration of the cameras including a geometric calibration as well as a radiometric characterization is provided, allowing for the computation of absolute calibrated, georeferenced Stokes vectors rotated into the scattering plane. We validate the calibration by comparing sunglint measurements to radiative transfer simulations.

Accuracy is important in wind speed measurements with cup anemometers. Dynamic overspeeding is historically considered an inherent and significant error, supported by a two-cup drag model. But lower (and even zero) overspeeding might be present for low-to-medium turbulence intensities for conical cups with short arms. A parabolic torque model reveals various dynamic overspeeding characteristics of cup anemometers, but modelling of actual cup anemometers is best made with tabulated data.

This paper evaluates the performance of an aircraft gas inlet. Here, we use computational fluid dynamics (CFD) and experiments to demonstrate the role of turbulence in determining sampling performance of a gas inlet and identify ideal conditions for inlet operation to minimize gas loss. Experiments conducted in a high-speed wind tunnel under near-aircraft speeds validated numerical results. We believe that the results obtained from this work will greatly inform future gas inlet studies.

In some clouds, liquid water droplets can freeze onto ice crystals (riming). Riming leads to the formation of snowflakes. We show two ways to quantify riming using aircraft data collected in the Arctic. One aircraft had a cloud radar, while the other aircraft was measuring directly in cloud. The first method compares radar and direct observations. The second looks at snowflake shape. Both methods agree, except when there were gaps in the cloud. This improves our ability to understand riming.

Aerosols are particles in the atmosphere that cool the climate by reflecting and absorbing sunlight (direct effect) and changing cloud properties (indirect effect). The scale of aerosol cooling is uncertain, hampering accurate climate predictions. We compare two algorithms for the retrieval of aerosol properties from multi-angle polarimetric measurements: Generalized Retrieval of Atmosphere and Surface Properties (GRASP) and Remote sensing of Trace gas and Aerosol Products (RemoTAP).

Organic aerosol constitutes a significant portion of atmospheric fine particles but is less characterized due to its vast number of constituents. Recently, we developed a system for online measurements of particle-phase highly oxygenated organic molecules (HOMs). In this work, we systematically characterized the system, developed a new unit to enhance its performance, and demonstrated the essential role of thermograms in inferring volatility and quantifying HOMs in organic aerosols.

Polymer absorption of volatile organic compounds (VOCs) is important to characterize for atmospheric sampling setups (as interactions cause sampling delays) and indoor air quality. Here we test different polymer materials and quantify their absorptive capacities through modeling. We found the main polymers in carpets to be highly absorptive, acting as large reservoirs for indoor pollution. We also demonstrated how polymer tubes can be used as a low-cost gas separation technique.

A novel infrared imaging instrument (OH imager) was put into operation in November 2022 at the Swedish Institute of Space Physics in Kiruna (Sweden). The OH imager is dedicated to the study of nightglow emissions coming from the hydroxyl (OH) and molecular oxygen (O₂) layers in the mesopause (80–100 km). Based on a brightness ratio of two OH emission lines, the neutral temperature is estimated at around 87 km. The average daily winter temperature for the period January–April 2023 is 203±10 K.

In this study, we examine the extent to which radar measurements from space can inform us about the properties of clouds and precipitation. Surprisingly, our analysis showed that the amount of ice turning into rain was lower than expected in the current product. To improve on this, we came up with a new way to extract information about the size and concentration of particles from radar data. As long as we use this method in the right conditions, we can even estimate how dense the ice is.

We provide the first validation of the satellite-derived emission estimates using surface-based mobile greenhouse gas surveys of an active gas leak detected near Cheltenham, UK. GHGSat’s emission estimates broadly agree with the surface-based mobile survey and steps were taken to fix the leak, highlighting the importance of satellite data in identifying emissions and helping to reduce our human impact on climate change.