The paper aims to study the ground reflection, or clutter, of the signal from a spaceborne radar in the context of ESA's WIVERN (WInd VElocity Radar Nephoscop) mission, which will observe in-cloud winds. Using topography and land type data, with a model of the satellite orbit and rotating antenna, simulations of scans have been run over the Piedmont region of Italy. These measurements cover the full range of the ground clutter over land for WIVERN and have allowed for analyses of the precision and accuracy of velocity observations.

The Three-Dimensional Precipitation Particle Imager (3D-PPI) was introduced as a new instrument to measure the three-dimensional shape, size, and falling velocity of precipitation particles. Field experiments of the 3D-PPI were conducted in Tulihe, China, during the winter of 2023 to 2024. More than 880 000 snowflakes in a typical snowfall case lasting 13 h were recorded. It shows potential applications in atmospheric science, polar research, and other fields.

We present a novel method for classifying rain and snow by combining data from commercial microwave links (CMLs) with weather radar. We compare this to a reference method using dew point temperature for precipitation type classification. Evaluations with nearby disdrometers show that CMLs improve the classification of dry snow and rainfall, outperforming the reference method.

An operational aerosol effective height (AEH) retrieval algorithm for the Geostationary Environment Monitoring Spectrometer (GEMS) was developed that solely uses the O²–O² absorption band considering aerosol and surface properties. AEH retrievals are only performed when aerosol optical depth is larger than 0.3. The retrieval results show significant estimations by comparing the aerosol height from the Cloud–Aerosol Lidar with Orthogonal Polarization and the Tropospheric Monitoring Instrument.

The new high-time-resolution sampler STRAS has been designed, developed and tested. It enables automatic sequential sampling of up to 168 hourly samples of PM₁₀, PM_2.5 or PM₁. It has been conceived for subsequent elemental composition analysis (from Na to Pb) by particle-induced X-ray emission (PIXE), but optical techniques may also be applied to measure black and brown carbon. Its use combined with other high-temporal-resolution instrumentation can provide complete chemical speciation of aerosols on an hourly basis.

We tested a variety of scientific measurements and algorithms for distinguishing the amounts of air pollution that were emitted by a nearby polluter from background pollution that was already in the air. The results show that machine learning and other statistical algorithms produced accurate estimates of this background pollution. These findings help scientists and regulators to understand where pollution comes from and to improve measurements of pollution from sources like traffic.

Low-cost optical particle counters (OPCs) offer new opportunities to monitor dust particles from wind soil erosion. Their price, size, and power consumption are lower than those of traditional OPCs. We tested the ability of the low-cost OPC-N3 from Alphasense to estimate dust emission flux during erosion events in Jordan. N3 estimated the dust flux well, with differences of less than 30 % compared to a traditional OPC. Our results confirm the potential of low-cost OPCs for dust erosion research.

ESA's Aeolus mission, launched in 2018, has exceeded expectations, providing valuable global wind lidar data for nearly 5 years. Its data have improved weather forecasting, with Mie-cloudy winds proving to be especially precise. Challenges have emerged, such as unexpected misalignments in signal angles and reduced signal levels due to beam clipping and laser issues. Lessons from Aeolus highlight the need for better optical alignment and active control systems for future lidar missions.

A robust, automatic volatile organic compound (VOC) collection system was developed for vertical VOC sampling associated with the 2022 DOE ARM-program-led TRACER in Houston, Texas.  This modular sampler has been developed to measure vertical profiles of VOCs to improve near-surface characterization. This article helps fill the current lack of commercially available options for aerial VOC sampling and serves to support and encourage researchers to build and develop custom samplers. 

The SAMURAI-S system is an innovative measurement tool combining a high accuracy wind sensor with a multi-rotor drone to improve atmospheric turbulence observations. While traditional methods lack flexibility and accuracy in dynamic environments, SAMURAI-S provides high maneuverability and precise 3D wind measurements. The research demonstrated the system's ability to match the data quality of conventional methods, with a slight overestimation in vertical turbulence under higher wind conditions.

Our research introduces a novel deep-learning approach for classifying and segmenting ground-based infrared thermal images, a crucial step in cloud monitoring. Tests based on self-captured data showcase its excellent accuracy in distinguishing image types and in structure segmentation. With potential applications in astronomical observations, our work pioneers a robust solution for ground-based sky quality assessment, promising advancements in the photometric observation experiments.

We analyzed signal delays in the atmosphere, using eight co-located global navigation satellite system (GNSS) stations, and compared linear horizontal gradients with microwave radiometer data. A weak constraint applied when estimating gradients in the GNSS data processing, enhancing short-lived gradient tracking but increasing noise, which can be mitigated by averaging gradients from the eight stations. This approach may enhance GNSS-based atmospheric monitoring for use in weather nowcasting.

This paper presents a comprehensive calibration procedure for the first spaceborne high-spectral-resolution lidar with an iodine vapor absorption filter Aerosol and Carbon Detection Lidar (ACDL) on board DQ-1 by utilizing nighttime 532 nm multi-channel data. We analyzed the error sources of the multi-channel calibration coefficients and assessed the results. The results indicate that the uncertainty of the clear-air scattering ratio was within the anticipated range of 7.9 %.

Atmospheric stability indicates whether air vertical motion is dumped or amplified. This is important for wind energy applications as it affects wind turbine wakes and thus the yield of wind parks. The paper provides an assessment of stability metrics measured by ground-based microwave radiometers in different climatological conditions and instrument types, onshore and offshore. Results indicate that special precaution may be required offshore to achieve typical onshore performances.

Aerosol composition has a large influence on the climate system. This study uses realistic simulated scenarios to look at the information content of a combination of three satellite-based instruments (SLSTR, IASI and GOME-2). It shows that it is possible to retrieve 6 to 15 different aerosol components in addition to the aerosol optical depth (AOD) and different surface parameters. The results are used for the development of a synergistic multi-sensor retrieval algorithm.

Water is a precious resource, and it is essential to monitor and predict the current and future occurrence of precipitation-producing clouds. We investigate the cloud characteristics related to precipitation using several cloud cases in the United Arab Emirates with data from aircraft measurements, satellite observations, and weather radar observations. This study provides scientific support for the development of an applicable framework to examine cloud precipitation processes.

Long-term records of plant fluorescence offer vital insights into changing vegetation activity. The GOME-2A sensor provides extensive global observations but suffers from calibration and instrument degradation, which affects data consistency. This study presents the SIFTER v3 algorithm, which effectively resolves these issues and includes other improvements, resulting in robust, accurate, and consistent GOME-2A fluorescence measurements from 2007 to 2017.

Detection of NO₂ via cavity ring-down spectroscopy (CRDS) after thermal dissociation (TD) of alkyl and peroxy nitrates can be used to detect total atmospheric organic nitrates originating from the interaction between biogenic emissions of volatile organic compounds and nitrogen oxides of anthropogenic origin. Here we present an improved TD-CRDS technique that avoids systematic bias resulting from secondary chemistry in the heated inlets and that can be deployed in regions with strong biogenic emissions.

Fog and low stratus (FLS) are both persistent clouds close to the Earth's surface. This study introduces a new machine-learning-based algorithm developed for the Meteosat Second Generation geostationary satellites that can provide a coherent and detailed view of FLS development over large areas over the 24 h day cycle.