The aerosol climatology over 2001–2014 was obtained in Moscow within AERONET. The best data quality has been accessed after additional cloud correction, which decreases AOT up to 0.03 at 500 nm. The additional NO₂ correction of up to 0.015 should be applied in megacities with large NO_x emission rates. The pronounced negative AOT trends of about −1–5% per year were observed for most months, which could be attributed to the negative trends in emissions of different aerosol precursors.

This study discusses the ionospheric correction problem of RO data in the troposphere and investigates an optimal transition height (OTH) for replacing the standard linear combination method by the L1–L2 bending angle extrapolated from above. By comparing the RO ionosphere-free bending angles with the ECMWF global forecast ones, the OTH is found when it gives the minimal standard deviations. The results show the OTH depends mainly on the L2 signal and is ~20 km for COSMIC L2P and ~10 km for L2C.

Motivated by unreliable sensor readings and the difficulties in calibrating sensors, we developed a Bayesian-network-based method to remove the abnormal readings and re-calibrate the sensors.

The interplay between aerosols and the OMI O₂–O₂ cloud retrieval algorithm is analysed in detail to evaluate the impacts on the accuracy of the tropospheric NO₂ retrievals over cloud-free scenes. Collocated OMI NO₂ and MODIS Aqua aerosol products are compared over E China, in industrialized areas; the OMI O₂–O₂ cloud retrieval algorithm is implemented on synthetic study cases dominated by aerosol particles. The resulting biases highlight the need for an improved aerosol correction.

The three GOME-2 instruments will provide unique and long data sets for atmospheric research and applications. The complete time period will be 2007–2022, including the period of ozone depletion as well as the beginning of ozone layer recovery. The GOME-2 products (ozone, trace gases, aerosols and UV radiation) are important for ozone chemistry, air quality studies, climate modeling, policy monitoring and hazard warnings. The processing and dissemination is done by EUMETSAT O3M SAF project.

A satellite based surface visibility retrieval has been developed for the GOES-R ABI instrument using MODIS proxy data and validated using independent ASOS surface visibility measurements. Variability in the frequency of clear sky (aerosol) surface visibility retrievals larger than 20 dV is shown to be correlated with seasonal and interannual variability in fire detections, illustrating the importance of smoke from wildfires in regional haze events.

We have developed a two-channel broadband cavity enhanced absorption spectrometer for field measurements of glyoxal, methylglyoxal, nitrous acid, nitrogen dioxide, and water. We have successfully deployed this instrument during two aircraft and two ground-based field campaigns. The demonstrated precision (2σ) for retrievals of CHOCHO, HONO, and NO₂ are 34, 350, and 80 parts per trillion (pptv) in 5 s, with accuracy of 5.8, 9.0 and 5.0 %.

Organic carbon and elemental carbon are major components of atmospheric PM. Typically they are measured using destructive and relatively expensive methods (e.g., TOR). We aim to reduce the operating costs of large air quality monitoring networks using FT-IR spectra of ambient PTFE filters and PLS regression. We achieve accurate predictions for models (calibrated in 2011) that use samples collected at the same or different sites of the calibration data set and in a different year (2013).

In this paper a newly developed scanning 35 GHz cloud radar MIRA-35 is described. The issues concerned with implementation, polarization calibration, and data processing are considered. Also, an algorithm for a characterization of shape and orientation distribution based on polarimetric observations from the cloud radar is presented. For demonstration, the developed retrieval technique is applied to a cloud system containing ice crystals with different habits.

Human activities have increased mercury (Hg) cycling between land and atmosphere. To define landscapes as sinks or sources of Hg we have developed an advanced REA system for long-term measurements of gaseous elemental Hg exchange. It was tested in two contrasting environments: above Basel, Switzerland, and a peatland in Sweden. Both landscapes showed net Hg emission (15 and 3 ng m⁻² h⁻¹, respectively). The novel system will help to advance our understanding of Hg exchange on an ecosystem scale.

A newly developed instrument, the Sequential Spot Sampler (S3) was evaluated in the laboratory and field for the hourly measurement of ambient PM_2.5 nitrate and sulfate concentrations. The results from the comparison of two S3s and the S3s with other well-established methods show that this instrument is suitable for deployment; provides high-resolution aerosol nitrate and sulfate concentrations while requiring minimal operator involvement and low power input; and has a small footprint.

This study examines various microphysical properties of liquid and solid hydrometeors to investigate their relationship with lightning activity. Measurements were collected from the Polar 55C dual-polarization radar, a 2-DVD, and LINET. From the analysis of three significant case studies, linear relations between the total mass of graupel and the number of strokes were found. Results point out the key role of ice mass in determining the electrical charging of convective clouds.

We report on the use of thermal dissociation cavity ring-down spectroscopy to detect NO₂, peroxy nitrates and alkyl nitrates. We present both laboratory studies that characterise the chemical formation and loss of NO₂ in the heated inlets and also result from a first field deployment.

The column-averaged dry-air mole fraction of CO₂ has been retrieved from high-resolution solar absorption spectra from two different measurement networks. We investigate the differences between these retrievals and find that their sensitivity differs greatly. As a result the direct comparison of the two retrievals remains challenging.

We present a dynamic twin-cuvette system for quantifying the trace gas exchange fluxes between plants and the atmosphere under controlled temperature, light, and humidity conditions. We found out that at a relative humidity of 40 %, the deposition velocity ratio of O₃ and PAN was determined to be 0.45. At that humidity, the O₃-deposition to the plant leaves was found to be only controlled by leaf stomata. For PAN, an additional resistance inhibited the uptake of PAN by the leaves.

Measurements of clouds with an aircraft are essential to understand how clouds form and how they affect the Earth's climate. These measurements are used in climate models to help predict how our climate might develop in the next century. Aircraft measurements are, however, difficult for modellers to interpret because the way they were acquired and analyzed varies from one team of scientists to the next. We present a software platform for scientists to share and compare their analysis tools.

This paper presents the new photometer CE318-T, able to perform daytime and night-time photometric measurements using the sun and the moon as light sources. This new device permits a complete cycle of diurnal aerosol and water vapour measurements to be extracted, valuable to enhance atmospheric monitoring. We have also highlighted the ability of this new device to capture short-term atmospheric variations, critical for climate studies.

A novel experimental set-up based on piezoelectric crystal microbalances has been used to monitor the sublimation processes concerning some volatile organic compounds present in the terrestrial atmosphere. The experimental set-up has been developed and tested on dicarboxylic acids. By means of the molecular flux, it has been possible to infer the enthalpy of sublimation of oxalic, succinic, adipic and azelaic acid. The results obtained are in very good agreement with previous works.

To accurately estimate source and sink locations of carbon dioxide, systematic errors in satellite measurements and models must be characterized. This paper examines two satellite data sets (GOSAT, launched 2009, and SCIAMACHY, launched 2002), and two models (CarbonTracker and MACC) vs. the TCCON CO2 validation data set. We assess biases and errors by season and latitude, satellite performance under averaging, and diurnal variability. Our findings are useful for assimilation of satellite data.

Cloud base height observations from Ceilometer CL31 were extensively studied during May 2013 to January 2015 over Ahmedabad (23.03°N, 72.54°E), India. Results indicate that the ceilometer is an excellent instrument to precisely detect low- and mid-level clouds, and that the MODIS satellite provides accurate retrieval of high-level clouds over this region.

The paper presents the development of a new retrieval scheme to infer near-surface sulfur dioxide (SO₂) concentrations at a global scale from the Infrared Atmospheric Sounding Interferometer (IASI). It demonstrates the capability of such an instrument to globally monitor anthropogenic SO₂ pollution in the case of favourable geophysical conditions, especially high thermal contrast and low humidity.

We have improved the reliability of submicron aerosol particle size distributions measured in urban locations. This improvement was obtained by processing the data in a new way and avoiding a problematic assumption of a stationary aerosol during each size distribution measurement.

This paper proposes a new cloud classification method, named bag of micro-structures (BoMS), for whole-sky imagers. BoMS treats an all-sky image as a collection of micro-structures mapped from image patches, rather than a collection of pixels. BoMS identifies five different sky conditions: cirriform, cumuliform, stratiform, clear sky, and mixed cloudiness (often appearing in all-sky images but seldom addressed in the literature). The performance of BoMS overperforms those of traditional methods.

We compare concentration profiles of methane and nitrous oxide measured from MIPAS-ENVISAT and derived with a new retrieval setup to those measured by other satellite instruments and to surface measurements. For methane we use profiles measured by ACE-FTS, HALOE and SCIAMACHY; for nitrous oxide we use profiles measured by ACE-FTS, Aura-MLS and Odin-SMR for the comparisons. We give a quantitative bias estimation and compare the estimated errors provided by the instruments.

This paper provides a preliminary validation for the refractivity of GNOS, a new addition to the space-based radio occultation sounder on FY-3C. It possesses a similar sounding capability that COSMIC and GRAS did in the vertical range of 0-30 km, with a precision below 1 %.

Height-resolved limb radiance spectra of the satellite instrument SCIAMACHY are used to retrieve cloud top heights with a colour index method. Clouds are detectable from the lower to the uppermost troposphere. These cloud heights help to improve the trace gas retrieval for the upper troposphere and lower stratosphere. Comparisons with other data sets have shown good agreement. As clouds and aerosols are not distinguishable, lower stratospheric volcanic aerosol clouds are detected in some years.

Current commercially available Doppler lidars provide a cost-effective solution for measuring vertical and horizontal wind velocities, and the co- and cross-polarised backscatter profiles. However, the background noise behaviour becomes a limiting factor for the instrument sensitivity in low aerosol load regions. In this paper we present a correction method which can improve the data availability up to 50 % and greatly improves the calculation of turbulent properties in weak signal regimes.

This paper describes the use of pseudorandom coded continuous wave radar transmissions for meteor radar. This avoids range-aliased echoes, maximizes pulse compression gain, is less susceptible to RFI, allows time resolution to be changed flexibly, and enables multiple transmitters to operate on the same frequency without interfering each other. These features make the radar well suited for multi-static meteor radar networks. We show results from a measurement campaign to demonstrate the method.

By modeling the Special Sensor Microwave Imager/Sounder's mesospheric measurements, inversions methods can be applied to retreive mesospheric temperatures. We compare the fast forward model used by Met Office with reference simulations and find that there is a reasonable agreement between both models and measurements. Thus we recommend that the fast model is used in data assimilation to improve mesospheric temperature retrievals.