This study discusses the morning and afternoon distribution of NO₂ emissions in large cities and industrial areas in South Korea, one of the largest NO₂ emitters around the world, using GeoTASO, an airborne remote sensing instrument developed to support geostationary satellite missions. NO₂ measurements from GeoTASO were compared with those from ground-based remote sensing instruments including Pandora and in situ sensors.

In this work, we analyze polarized cloudbow observations by the airborne camera system specMACS to retrieve the cloud droplet size distribution defined by the effective radius (r_eff) and the effective variance (v_eff). Two case studies of trade-wind cumulus clouds observed during the EUREC⁴A field campaign are presented. The results are combined into maps of r_eff and v_eff with a very high spatial resolution (100 m × 100 m) that allow new insights into cloud microphysics.

Methane and carbon monoxide are important constituents of the atmosphere in the context of climate change and air pollution. We present the latest advances in the TROPOMI/WFMD algorithm to simultaneously retrieve atmospheric methane and carbon monoxide abundances from space. The changes in the latest product version are described in detail, and the resulting improvements are demonstrated. An overview of the products is provided including a discussion of annual increases and validation results.

Hailstones often exhibit opaque and clear ice layers that have an onion-like appearance. These layers are record of the conditions during growth and can be simulated by hail growth models. A new technique for automating the measurement of these layers from hail cross sections is demonstrated. This technique is applied to a collection of hailstones from Melbourne, Australia, to understand their growth evolution, and a first look at evaluating a hail growth model is demonstrated.

Our study addresses raindrop size distribution and rain rate by extracting rain streaks using a k-nearest-neighbor-based algorithm, estimating rainfall intensity using raindrop size distribution based on physical optics analysis, and verifying the estimated raindrop size distribution using a disdrometer. Experimentation demonstrated the possibility of estimating an image-based raindrop size distribution and rain rate obtained based on such low-cost equipment in dark conditions.

This paper investigates the Absolute Cavity Pyrgeometer (ACP) and its use in measuring atmospheric terrestrial irradiances traceable to the standard system of units (SI). This work fits into the objective of the Expert Team on Radiation References, established by the World Meteorological Organization (WMO), to develop and validate instrumentation that can be used as reference instruments for terrestrial radiation measurements.

The accurate identification of aerosol types in the stratosphere is important to characterize their impacts on the Earth climate system. The space-borne lidar on board CALIPSO is well-posed to identify aerosols in the stratosphere from volcanic eruptions and major wildfire events. This paper describes improvements implemented in the version 4.5 CALIPSO data release to more accurately discriminate between volcanic ash, sulfate, and smoke within the stratosphere.

It is challenging to make field measurements of stable water isotopes in the Arctic. To this end, we present a modular stable-water-isotope analyzer profiling system. The system operated for a 2-week field campaign on Svalbard during the Arctic winter. We evaluate the system’s performance and analyze any potential impact that the field conditions might have had on the isotopic measurements and the system's ability to resolve isotope gradients in the lowermost layer of the atmosphere.

An instrument for in situ continuous 2 km vertical profiles of temperature below high-altitude balloons was developed for high-temporal-resolution measurements within the upper troposphere and lower stratosphere using fiber-optic distributed temperature sensing. The mechanical, electrical, and temperature calibration systems were validated from a short mid-latitude constant-altitude balloon flight within the lower stratosphere. The instrument observed small-scale and inertial gravity waves.

In this study, we compute the distributed sensible heat flux using a distributed temperature sensing technique, whose magnitude, sign, and temporal dynamics compare reasonably well to estimates from classical eddy covariance measurements from sonic anemometry. Despite the remaining uncertainty in computed fluxes, the results demonstrate the potential of the novel method to compute spatially resolving sensible heat flux measurement and encourage further research.

Carbon-containing aerosols from ambient air are analysed for radioactive isotope radiocarbon to determine the contribution from fossil-fuel emissions. Light-absorbing soot-like aerosols are isolated by water extraction and thermal separation. This separation is affected by artefacts, for which we developed a new correction method. The investigation of aerosols from the Arctic shows that our approach works well for such samples, where many artefacts are expected.

Since the winds in clear-air conditions usually play an important role in the initiation of various weather systems and phenomena, the modified Wind Synthesis System using Doppler Measurements (WISSDOM) synthesis scheme was developed to derive high-quality and high-spatial-resolution 3D winds under clear-air conditions. The performance and accuracy of derived 3D winds from this modified scheme were evaluated with an extreme strong wind event over complex terrain in Pyeongchang, South Korea.