This study assesses the capability of the EUMETSAT Sentinel-6A radio occultation (RO) non-time-critical processor to generate high-quality bending angle profiles. The analysis examines various aspects of both the RO instrument and the bending angle processing chain. The resulting bending angle profiles were compared against forward-modeled profiles from the European Centre for Medium-Range Weather Forecasts (ECMWF), confirming the processor's ability to consistently produce accurate and reliable data.

This paper presents a novel technique to extract starlight signals from all-sky images and retrieve aerosol optical depth (AOD). It is validated against lunar photometry, showing a strong correlation between data series. This innovative approach will expand nocturnal AOD measurements to more locations, as all-sky cameras are a simpler and more cost-effective alternative to stellar and lunar photometers.

We developed a new method to estimate how much heat the ocean surface receives from the atmosphere, which is important for understanding weather and climate. Using over 30 years of data from buoys around the world, we created a model that outperforms existing ones, especially under cloudy skies. Our results show that including detailed cloud information improves accuracy, making this method useful for global climate and ocean research.

The Pandonia Global Network (PGN) consists of Pandora spectrometers that observe trace gases at a high time resolution to validate satellite observations and understand local air quality. To aid users, PGN assigns quality flags that assure scientifically valid data but eliminate large amounts of data appropriate for scientific applications. A new method based on contemporaneous data in two independent observation modes is proven using complementary ground-based and airborne observations.

We assess and illustrate the benefits of high-altitude attainment of balloon-borne radiosonde soundings up to and beyond 10 hPa level from various aspects. We show that the extra costs and technical challenges involved in consistent attainment of high ascents are more than outweighed by the benefits for a broad variety of real-time and delayed-mode applications. Consistent attainment of high ascents should therefore be pursued across the balloon observational network.

We use balloon-borne measurements of aerosol size distribution (ASD) made by the University of Wyoming (UW) to derive distributions which are representative of the ASDs that underlie measurements made by the Stratospheric Aerosol and Gas Experiment II (SAGE II). A simple single-mode log-normal distribution has in the past been used to derive ASD from SAGE II data; here we derive bimodal log-normal distributions, reproducing median aerosol properties measured by UW.

We present a new instrument based on digital in-line holography (SmHOLIMO) for in situ cloud measurements. SmHOLIMO is designed to specifically measure small cloud droplets with diameters > 3.7 μm. This way we retrieve accurate cloud droplet size distributions, which are crucial to understand the evolution and governing microphysical processes of a cloud. Results of a field study are compared to co-located measurements of a second holographic imager, microwave radiometer, and cloud radar.

Orphaned wells, meaning wells lacking responsible owners, pose a significant and poorly understood environmental challenge. We propose, develop and test a novel method for estimating emissions from orphaned wells using a forced advection sampling technique (FAST) that can overcome many of the limitations in current methods (cost, accuracy, safety). Our results suggest that the FAST method can provide a low-cost alternative to existing methods over a range of leak rates.

Satellites can measure cloud geometry using stereoscopy. However, clouds are transparent and often have tenuous boundaries. We evaluate the effect of this on stereoscopy using numerical simulations. Stereoscopic techniques retrieve a cloud boundary that is ~100 m interior to the true boundary and is smoother, depending on the cloud shape and resolution of the instrument. This error is similar across views, demonstrating the strength of stereoscopy for detecting changes in cloud geometry.

A wind speed correction algorithm for multirotor unoccupied aerial vehicles (UAVs) was developed using computational fluid dynamics (CFD). An integrated compensation algorithm was designed to account for the effects of UAV motion, attitude changes, and rotor-induced airflow on wind speed measurements. Comparative experimental results confirmed the effectiveness of the proposed compensation algorithm.

It is of increasing importance to monitor nitrate pollution that can harm ecosystems. However, commonly used aerosol monitoring equipment cannot distinguish inorganic from organic forms of nitrate, which may have different consequences for the environment. We describe a method to differentiate types of nitrates that can be applied to ambient monitoring to improve understanding of its formation and impact.

We have used absorption from a photothermal interferometer and scattering measurements to evaluate the most deployed filter photometers used to measure absorption for monitoring networks. We used soot- and dust-dominated aerosol samples in both laboratory and ambient settings. Our results indicated that one of these filter photometers, the MAAP (Multiangle Absorption Photometer), usually used as a pseudo-reference instrument, had 47 % higher absorption values than our reference measurements.

Measurements made by three instruments aboard EarthCARE are used to retrieve estimates of cloud and aerosol properties. A radiative closure assessment of these retrievals is performed by the ACMB-DF processor. Radiative transfer models acting on retrieved information produce broadband radiances commensurate with measurements made by EarthCARE’s broadband radiometer. Measured and modelled radiances for small domains are compared, and the likelihood of them differing by 10 W m² defines the closure.

This paper presents long-term observations of atmospheric CO₂ and CH₄ mole fractions and a comparison of two permanent and two mobile measurement systems located in Northern Finland. Furthermore, the observed mole fractions are compared against the mean marine boundary layer product for the Northern Hemisphere. The comparisons of all the systems show good agreement in relation to the World Meteorological Organization/Global Atmosphere Watch network compatibility goal limits for CO₂ and CH₄.

PurpleAir sensors provide a low-cost way to monitor air quality, with over 30 000 sensors available worldwide. However, their measurements require calibration with trusted data for accuracy. Our new technique builds on previous calibration methods by also enabling the measurement of a quantity related to how pollutants grow with humidity. Mapping this new quantity will improve air quality forecasting.

Air quality sensors often underpredict peak concentrations, which is a major issue in applications such as emission event detection. Here, we detail a novel approach involving data weighting to improve quantification of these peak values. To demonstrate its effectiveness, we applied data weighting to carbon monoxide, methane, and volatile organic compound sensor data. This work broadens our ability to use air sensors in contexts where accurate quantification of peak concentrations is essential.

A new aerological dropsonde system for research aircraft has been developed. The system allows up to four sondes to be dropped with one release container, and data from up to 30 sondes can be transmitted simultaneously. The sondes enable high-resolution profiling of temperature, humidity, pressure, and wind. Additional sensors for radioactivity and particles have been integrated and tested. Operations in different campaigns have confirmed the reliability of the system and the quality of data.

This study presents the humidity measurements with a synergistic algorithm combining Raman lidar,  microwave radiometer, and satellite. The results from 47 sites in China show the best correlation over 0.9 concerning the radiosonde measurements. This validates the relative humidity (RH) accuracy with various data integrations. Three representative sites present the different seasonal characteristics, indicating the geographic and height influences on the RH vertical distribution.

Over the past two decades, global flux tower networks have provided valuable insights into ecosystem functioning. However, the standard eddy-covariance method used for processing flux data has limitations, leading to data loss and limited resolution due to fixed time steps. This paper introduces a new method using wavelet analysis to increase temporal resolution and improve data retention. Applied at the Hesse forest flux tower in France, this approach provides high-resolution flux estimates, enhancing the accuracy of flux measurements.

Using about 120 000 occultations recorded by the Sentinel-6A and COSMIC-2 satellites, we show that using high-rate (1 s) GLONASS clock products greatly improves GLONASS occultation statistics and vertical error correlation. For GPS, the best performance is obtained with 5 s clock products. These findings result from the short-timescale behavior of the onboard atomic clocks and are important given the impact of radio occultation measurements on numerical weather predictions and climate studies.

This paper describes a modified RainGaugeQC system for real-time quality control of rain gauge measurements made every 10 min. It has been significantly modified to control data from non-professional and private measurement networks of lower quality than professional data. The modifications went in the direction of performing more sophisticated data control, applying weather radar data, and taking into account various aspects such as consistency analysis of data time series and bias detection.