Abstracted/indexed

In our paper, we propose a robust and operational algorithm to determine the height of the Fre ezing level that can be applied to either Quasi-Vertical Profiles (QVPs) or Vertical profiles (VPs) of polarimetric radar variables. The algorithm is applied over one year of rainfall events collected by a C-Band operational weather radar located in the UK and validated using measured FLs from radiosonde. The results confirm that the algorithm estimates the FL accurately.

The Japanese Greenhouse gases Observing SATellite-2 (GOSAT-2), in orbit since October 2018, is the follow-up mission of GOSAT, which has been operating since January 2009. Both satellites are dedicated to the monitoring of global carbon dioxide and methane to further knowledge of the global carbon cycle. This paper has reported on the function and performance of the TANSO-FTS-2 instrument, level-1 data processing, and calibrations for the first year of GOSAT-2 observation.

Cloud radars are powerful instruments that can probe detailed cloud structures. However, radar echoes in the lower atmosphere are always contaminated by clutters. We proposed a multi-dimensional probability distribution function that can effectively discriminate low-level clouds from clutters by considering their different features in several variables. We applied this method to the radar observations at SACOL site and found the results have a good agreement with lidar detections.

Temperature and humidity profiles in the lowest couple kilometers near the surface are very important for many applications. Passive spectral radiometers are commercially available, and observations from these instruments have been used to get these profiles. However, new active lidar systems are able to measure partial profiles of water vapor. This paper investigates how the derived profiles of water vapor and temperature are improved with the active and passive observations are combined.

We evaluated the suitability of fiber-optic distributed temperature sensing (DTS) to observe spatial (>25 cm) and temporal (>1 s) details of the air flow within and above forests. The DTS measurements were able to discern up to 3rd order moments of the flow and observe spatial details of coherent flow motions. Similar measurements are not possible with more conventional measurement techniques. Hence the DTS measurements will provide key insights into flows close to roughness elements, e.g. trees.

To demonstrate the robustness and comparability of the novel primary mercury gas standard, the results of comparisons are presented with current calibration methods maintained, using the bell-jar in combination with the Dumarey equation or NIST liquid standard reference material. The results show that the primary standard and the NIST reference material are comparable, whereas a difference of −8 % exists between results traceable to the primary standard and the Dumarey equation.

we apply a principal component analysis (PCA)-based approach combined with look-up tables (LUTs) of corrections to accelerate the VLIDORT radiative transfer (RT) model used in the retrieval of ozone profiles from backscattered ultraviolet (UV) measurements by the Ozone Monitoring Instrument (OMI).

When a meteor enters the atmosphere it causes a trail of diffusing plasma that moves with the neutral wind. An interferometric radar system can measure such trails and determine its location. However, there is a chance of determining the wrong position due to noise. We simulate this behavior and use the simulations to successfully determine the true location of ambiguous events. We also successfully test a simple temporal integration method for avoiding such erroneous determinations.

Aerosol property observations by satellites from Geostationary Earth Orbit(GEO) in particular have advantages of frequent sampling better than 1 hour in addition to broader spatial coverage. This study provides data fusion products of aerosol optical properties from four different algorithms for two different GEO Satellites, GOCI and AHI. The fused aerosol products adopted ensemble-mean and maximum-likelihood estimation methods.The data fusion provides improved results with better accuracy.

This work aims to use correlated IASI errors in the ozone band within a chemical transport model assimilation. The validation of the results against ozone observations from ozonesondes, MLS, and OMI instruments has shown an improvement of the ozone distribution. The computational time was also highly reduced. The surface sea temperature was also improved. The work aims to improve the quality of the ozone prediction which is important for air quality, climate, meteorological applications.

This study describes the implementation and characterization of the chemical modulation reactor (CMR) used in the laser-induced fluorescence instrument of the Forschungszentrum Jülich. The CMR allows for interference-free OH radical measurement in ambient air. During a field campaign in a rural environment, the observed interference was mostly below the detection limit of the instrument and fully explained by the known ozone interference.

This work describes the performance of an open-path measurement system for greenhouse gases in an extended field trial. The instrument obtained measurement repeatability of 0.1 % or better for CO₂ and CH₄ measurements over a 1.55 km one-way pathway. Comparison to co-located in situ measurements allows characterisation of biases relative to global reference scales. The research was done to show the applicability of the technique and its ability to detect atmospheric-relevant sources and sinks.

This paper presents an improved methodology for measurements of atmospheric concentration of carbon-14-containing carbon monoxide (¹⁴CO), as well as a 1-year data set that demonstrates the methodology. Atmospheric 14CO concentration measurements are useful for improving the understanding of spatial and temporal variability of hydroxyl radical concentrations. Key improvements over prior methods include a greatly reduced air sample size and accurate procedural blank characterization.

Concentrations of water vapor in the atmosphere vary dramatically over space and time. Mapping this variability can provide insights into atmospheric processes that help us understand atmospheric processes in the Earth system. Here we use a new measurement strategy based on imaging spectroscopy to map atmospheric water vapor concentrations at very small spatial scales. Experiments demonstrate the accuracy of this technique and some initial results from an airborne remote sensing experiment.

This research article presents a validation of 1.5 years of pure rotational temperature data measured by the Raman LIDAR RALMO installed at the MeteoSwiss station of Payerne. The statistical results are in terms of bias and standard deviation with respect to two well-established radiosounding systems. The statistics are divided into daytime (bias = 0.28 K, std = 0.62 ± 0.03 K) and nighttime (bias = 0.29 K, std = 0.66 ± 0.06 K). The Lidar temperature profiles are applied to cloud supersaturation studies.

The Brewer spectrophotometer is one of the main instruments for measurements of atmospheric total column ozone. The global Brewer network largely relies on the world reference instruments (the Brewer triad) operated by Environment and Climate Change Canada since the early 1980s. This study provides an updated assessment (1999–2019) of the reference instrument performance, in terms of random uncertainties and long-term stability.

Much effort has been put into obtaining crucial information about the progress of climate change and its main contributors such as tracegases like CO₂, Methane or aerosols. Satelitte-based spectrometer instruments, that analyze the light spectrum reflected by the earth are frequently sent into orbit to achieve this task. This work contributes a solution to a long known calibration problem and could significantly reduce overhead in future planning phases of such instruments and their performance.

This work describes the design, calibration and application of a hygrometer and sampling system, which have been developed and used for water content measurement in experimentally simulated atmospheric icing conditions with relevance in fundamental icing research, as well as aviation testing and certification. Together with a general description of water content measurement and accompanied uncertainties, results of a comparison to reference instruments in an icing wind tunnel are presented.

Aerosol hygroscopicity measured by HTDMA is affected by multiply charged particles from two aspects: (1) number contribution and (2) the weakening effect. We propose an algorithm to do the multi-charge correction for aerosol's size-resolved κ based on these two effects and applied it in a field measurement. Results show that the difference between corrected and measured κ can reach as large as 0.05, highlighting that special attention needs to be paid to the multi-charge effect by HTDMA.

We developed a wind measuring drone with exceptional measuring accuracy and a very long flight time. Measurements are extensively validated at different levels. A comparison with a bistatic lidar reveals very small bias and RMS errors. We also present a demonstration measurement in the wake of a wind turbine. We think that our solution is a significant enhancement to existing designs, and other researchers can benefit from the details that we are giving in the paper.

The study presents a comparison of three different absorption photometers that measured ambient aerosol particles at a boreal forest site. The study aims to better understand problems related to filter-based measurements. Results show how different correction algorithms, which are used to produce the data, affect the derived optical properties of aerosol particles.

In this paper we describe a new method to calculate the size of naturally occurring droplets (aerosols) made mostly of sulfuric acid and water, that can be found roughly in 20 km altitude in the atmosphere. For this we use data from the instrument SAGE III/ISS that is mounted on the International Space Station. We show that our method works well and that the size parameters we calculate are reasonable and can be a valuable addition to better understand the aerosols and their effect on climate.

We present an investigation of the usability of the newly developed real-time concentration monitoring systems, which are based on the gamma-ray counting of aerosol filters. These high resolution data were used for inverse modeling of the ¹⁰⁶Ru release in 2017. Our inverse modeling results agree with previously published estimates and provide better temporal resolution of the estimates.

Doppler wind lidars are laser-based remote sensing instruments that measure the wind up to a few hundred meters or even a few kilometers. Their data can improve weather models and help forecasters. To investigate their accuracy and required meteorological conditions we have carried out a two-year measurement campaign of a wind lidar at our Cabauw test site and made a comparison with cup anemometers and wind vanes at several levels in a 213-m tall meteorological mast.

The authors conducted the measurement of real-world CO₂ and NO_x emissions from one heavy-duty vehicle. The results showed that NO_x emission increased in the cold season because of the deactivation of the detoxification catalysis. We proposed an analytical model of vehicle emission based on the classical mechanic method. The model well explained the emission behavior of CO₂ and NO_x, and we concluded that the new model have the potential to evaluate the emission inventory from heavy-duty vehicles.

This work describes the newly released OMPS LP aerosol extinction profiles multi-wavelength Version 2.0 algorithm and data set. It is shown that the V2.0 aerosols exhibit significant improvements in OMPS LP retrieval performance in the Southern Hemisphere and at lower altitudes. The new product is compared to the SAGE III/ISS, OSIRIS and CALIPSO missions and shown to be of good quality and suitable for scientific studies.

This study investigates the level of channeling (optical resonances) of each FTIR spectrometer within the Network for the Detection of Atmospheric Composition Change (NDACC). Since the air gap of the beam splitter is a significant source of channeling, we propose new beam splitters with an increased wedge of the air gap. This study shows the potential for reducing channeling in the FTIR spectrometers operated by the NDACC, thereby increasing the quality of recorded spectra across the network.

Snow measurements are very sensitive to wind. Here we compare airflow and snowfall simulations to Arctic observations for a Multi-Angle Snowflake Camera to show that measurements of fall speed, orientation, and size are accurate only with a double wind fence and winds below 5 m s⁻¹. In this case, snowflakes tend to fall with a nearly horizontal orientation, and the largest flakes are as much as 5 times more likely to be observed. Adjustments are needed for snow falling in naturally turbulent air.

The Amazon basin influences the atmospheric and hydrological cycles on local to global scales. To better understand how, we plan to perform continuous on-site measurements of the stable isotope composition of atmospheric water vapour. For making accurate on-site observations possible, we have investigated the performance of two commercial analysers and determined the best calibration strategy. Well-calibrated, both analysers will allow us to record natural signals in the Amazon rainforest.

An instrument-dependent wavelength-independent parameter (C) is often used to face multiple-scattering issues affecting aerosol light-absorption measurements by Aethalometers. Opposite, we determined multi-wavelength C by comparison with absorption measurements of samples collected in parallel performed by an in-house developed instrument. Considering C wavelength-dependence, harmonized results were obtained applying source and component apportionment models to data from different Aethalometers.

The Earth’s climate is influenced by clouds, which are impacted by ice nucleating particles, a minor fraction of atmospheric aerosols. INPs induce ice formation in clouds and by that often initiate precipitation formation. The Portable Ice Nucleation Experiment PINE is the first fully automated instrument to study cloud ice formation and to obtain long-term records of INPs. This is a timely development and the capabilities it offers for research and atmospheric monitoring are significant.

This paper proposes a new method of Multichannel Microwave Radiometer 3-D antenna pattern measurement by observing the sun. The antenna pattern derived from the solar observation was compared with the result of the far-field measurement with a point source in the microwave anechoic chamber at 30 GHz, the maximum error of the beamwidth is less than 0.1°, which showed that this pattern matched well to the pattern measurement using a point source in the microwave anechoic chamber.

This work focuses on two important properties of the aerosol, acidity and sulfate composition, which are important for our understanding of aerosol health and environmental impacts. We explore different methods to understand the composition of the aerosol with measurements from a specific instrument, and apply those methods to a large dataset. These measurements are confounded by other factors, making it challenging to predict aerosol sulfate composition. pH estimations, however, show promise.

A LiDAR Statistical Barnes Objective Analysis (LiSBOA) for the optimal design of LiDAR scans and retrieval of the velocity statistics is proposed.The LiSBOA is validated and characterized via a Monte Carlo approach applied to a synthetic velocity field. The optimal design of LiDAR scans is formulated as a two cost-function optimization problem including the minimization of the volume not sampled with adequate spatial resolution and the minimization of the error on the mean of the velocity field.

The LiDAR Statistical Barnes Objective Analysis (LiSBOA) is applied to LiDAR data collected in the wake of wind turbines to reconstruct mean wind speed and turbulence intensity. This procedure is firstly tested for a numerical dataset obtained by means of the virtual LiDAR technique applied to LES data, then to data collected during a field campaign for a wind farm in complex terrain. The results endorse the application of the LiSBOA for LiDAR-based wind resource assessment and farm diagnostics.

Ammonia (NH₃) is a major source of pollution in the air. As such, there have been increasing efforts to measure the atmospheric abundance of NH₃ and its spatial and temporal variability. In this study, long-term measurements of NH₃ over Toronto, Canada, derived from multiscale datasets are examined. These NH₃ datasets were compared against each other, and against a model to better understand NH₃ variability, and to assess model performance.