Radiocarbon (¹⁴C) is an optimal tracer of methane (CH₄) emissions, as ¹⁴C measurements enable distinguishing between fossil methane and biogenic methane. However, these measurements are particularly challenging, mainly due to technical difficulties in the sampling procedure. We made the sample extraction much simpler and time efficient, providing a new technology that can be used by any research group, with the goal of expanding ¹⁴C measurements for an improved understanding of methane sources.

We compare passive aerosol layer height (ALH) retrievals from the Earth Polychromatic Imaging Camera (EPIC), TROPOspheric Monitoring Instrument (TROPOMI), and Geostationary Environment Monitoring Spectrometer (GEMS) with lidar. GEMS shows a lower correlation (R = 0.64) than EPIC and TROPOMI (R > 0.7) but with minimal bias (0.1 km vs. overestimated by ~0.8 km). GEMS performance is improved for an ultraviolet aerosol index ≥ 3. EPIC and GEMS ALH diurnal variation differs slightly.

In this paper, we present and evaluate a new method for the quantitative estimation of precipitation from a low-cost sensor. Based on previous work measuring the attenuation of an electromagnetic signal from a broadcast television satellite, we make this approach more accurate so it can be easily deployed and used operationally in areas where rainfall measurements are critical for applications like flood monitoring. In this article, the method is validated in France and applied in Côte d'Ivoire.

Accurate and comparable measurements of oxygenated organic compounds (OVOCs) are crucial in assessing tropospheric ozone burdens and trends. However, the monitoring of many OVOCs remains challenging because of their low atmospheric abundance and lack of stable and traceable calibration standards. This paper describes the calibration standards developed for OVOCs at a low amount of substance fractions (<100 nmol mol^-1) to transfer traceability of the International System of Units to the field.

The JPL lidar group developed the SMOL (Small Mobile Ozone Lidar), an affordable ozone differential absorption lidar (DIAL) system covering all altitudes from 200 m to 10 km a.g.l. The comparison with airborne in situ and lidar measurements shows very good agreement. An additional comparison with nearby surface ozone measuring instruments indicates unbiased measurements by the SMOL lidars down to 200 m a.g.l.

Glaciers preserve organic compounds from atmospheric aerosols, which can serve as markers for emission sources. Most studies overlook the enantiomers of chiral compounds. We developed a two-dimensional liquid chromatography method to determine the chiral ratios of the monoterpene oxidation products cis-pinic acid and cis-pinonic acid in ice-core samples. Applied to samples from the Belukha Glacier (1870–1970 CE), the method revealed fluctuating chiral ratios for the analytes.

Accurate measurement of nanoparticles is crucial for understanding their impact on new particle formation and climate change. In this study, we calibrated the Particle Size Magnifier version 2.0 (PSM 2.0), using both laboratory-generated and atmospheric particles. Some differences were observed in the calibration results, with direct calibration using atmospheric particles enhancing measurement accuracy.

Our research introduces a differential absorption lidar system for monitoring tropospheric ozone, utilizing a single CO₂ Raman cell. This technology enables the acquisition of high-resolution vertical ozone profiles from 0.3 to 4 km, essential for understanding air quality and climate impacts. 

The spatial adjacency of methane point sources can result in plume overlapping, presenting challenges for quantification from space. A separation and quantification method combining the Gaussian plume model and the integrated mass enhancement method is proposed. A modern parameter estimation technique is introduced to separate the overlapping plumes from satellite observations. The proposed method is evaluated with synthesized observations and real satellite observations.

This study evaluates and compares a new microwave hyperspectrometer with an infrared hyperspectrometer for clear-sky temperature and water vapor retrievals. The analysis reveals that the information content of the infrared hyperspectrometer exceeds that of the microwave hyperspectrometer and provides higher vertical resolution in ground-based zenith measurements. Leveraging the ground–airborne synergy between the two instruments yielded optimal sounding results.

We present a technique to discriminate between the Cloudnet target classification of "drizzle or rain" and sea salt aerosols that is applicable to marine Cloudnet sites. The method is crucial for investigating the occurrence of precipitation and significantly improves the Cloudnet target classification scheme for measurements over the Barbados Cloud Observatory (BCO). A first-ever analysis of the Cloudnet product including the new "haze echo" target over 2 years at the BCO is presented.

A Peltier-based chilled-mirror hygrometer, SKYDEW, has been developed to measure tropospheric and stratospheric water vapor. Continuous accurate measurements of water vapor are essential for climate monitoring. More than 40 soundings with SKYDEW have been conducted since 2011 to evaluate the performance. The result of soundings at tropical and midlatitudes demonstrated that SKYDEW is able to measure up to an altitude of 20–25 km for daytime soundings and above 25 km for nighttime soundings.

We study the capacity of XCO₂ spaceborne imagery to estimate urban CO₂ emissions with synthetic data. We define automatic and standard methods and objective criteria for image selection. The wind variability and urban emission budget guide the emission estimation error. Images with low wind variability and high urban emissions account for 47 % of images and give a bias in the emission estimation of −7 % and a spread of 56 %. Other images give a bias of −31 % and a spread of 99 %.

Hardware and software developments have been made on a 22 GHz microwave radiometer for the measurement of middle-atmospheric water vapour near Bern, Switzerland. Previous measurements dating back to 2010 have been re-calibrated and an improved optimal estimation retrieval performed on these measurements, giving a 13-year dataset. Measurements made with new and improved instrumental hardware are used to correct previous measurements, which show better agreement than the non-corrected dataset.