Cloud top height (CTH) is one of the important cloud parameters providing information about the vertical structure of cloud water content. To better understand the accuracy of CTH derived from passive satellite data, 2 years of ground-based Ka-band radar measurements are compared with CTH inferred from Terra/Aqua MODIS and Himawari AHI. It is found that MODIS and AHI underestimate CTH relative to radar by −1.10 km. Both MODIS and AHI CTH retrieval accuracy depend strongly on cloud depth.

THz Atmospheric Limb Sounder (TALIS) is a microwave limb sounder designed to measure the temperature and chemical species. The instrument will make an important contribution to monitoring the chemistry of the middle atmosphere. This paper describes the performance of this instrument. We use the radiative transfer model to evaluate its performance. As a result, the retrieval precision is quite acceptable.

We developed an improved two-sphere integration (TSI) technique to quantify black carbon (BC) concentrations in the atmosphere and seasonal snow. The major advantage of this system is that it combines two distinct integrated spheres to reduce the scattering effect due to light-absorbing particles and thus provides accurate determinations of total light absorption from BC collected on Nuclepore filters.

The Ice Cloud Imager (ICI) will be the first operational satellite sensor operating at sub-millimetre wavelengths and this novel mission will thus provide important new data to weather forecasting and climate studies. The series of ICI instruments will together cover about 20 years. This article presents the basic technical characteristics of the sensor and outlines the day-one operational retrievals. An updated estimation of the expected retrieval performance is also presented.

Air sample collection aboard aircraft is a tool to measure atmospheric trace gas mixing ratios at altitude. We present results on the stability of 28 halocarbons during storage of air samples collected in stainless-steel flasks inside an automated air sampling unit which is part of the CARIBIC instrument package. Selected fluorinated compounds grew during the experiments while short-lived compounds were depleted. Individual substances were additionally influenced by high mixing ratios of ozone.

This paper presents a new H₂O/HDO data set from TROPOMI short-wave infrared measurements. It is validated against recent ground-based FTIR measurements from the TCCON network. A bias in TCCON HDO (which is not verified) is corrected by fitting a correction factor for the HDO column to match MUSICA δD for common observations. The use of the new TROPOMI data set is demonstrated using a case study of a blocking anticyclone over Europe in July 2018.

Good-quality measurements of atmospheric trace gases are only possible with regular calibrations and stable measurements from the standard cylinders. This study investigates instabilities due to surface effects on newly built aluminum and steel cylinders. We present measurements over a set of temperature and pressure ranges for the amount fractions of CO₂, CO, CH₄ and H₂O using a commercial and a novel laser spectroscopic analyzer.

To ensure the best preparation and measurement conditions for trace gases, usage of coated materials is in demand in gas metrology and atmospheric measurement communities. In this article, the previously introduced aluminum measurement chamber is used to investigate materials such as glass, aluminum, copper, brass, steel and three different commercially available coatings. Our measurements focus on temperature and pressure dependencies for the species CO₂, CO, CH₄ and H₂O using a CRDS analyzer.

Bioaerosols are considered to play a relevant role in atmospheric processes, but their sources, properties, and spatiotemporal distribution in the atmosphere are not yet well characterized. Measurement data on the release of fungal spores under natural conditions are also sparse. Here, we present an experimental approach to analyze and quantify the spore release from fungi and other spore-producing organisms under natural and laboratory conditions.

New satellite sensors are able to view visible light, such as that emitted by cities, at night. It may be possible to use the light from cities to assess the amount of particulate matter in the atmosphere and the thickness of clouds. To do this we must understand how light emitted from the Earth's surface changes with time and viewing conditions. This study takes a step towards understanding the characteristics of light emitted by cities and its stability in time.

In this study, we aimed to improve accuracy of wind speed and direction measurements from an anemometer mounted atop a research vehicle. Controlled field tests and computer simulations showed that the vehicle shape biases airflow above the vehicle. The results indicate that placing an anemometer at a significant height (> 1 m) above the vehicle, and calibrating anemometer measurements for vehicle shape and wind angle, can be effective in reducing bias in measurements of wind speed and direction.

New satellite-based nitrogen dioxide (NO₂) data from TROPOMI/Sentinel 5P are used to monitor air pollution levels at the urban site of Helsinki, Finland. NO₂ is a polluting gas produced by fossil fuel combustion. TROPOMI NO₂ data agree with ground-based reference measurements within 10 % and show similar day-to-day and weekly variability. The results confirm that satellite-based observations can bring additional information to traditional in situ measurements for urban air quality monitoring.

Submillimeter-Wave Limb-Emission Sounder 2 (SMILES-2) is a satellite mission proposed in Japan to probe the middle and upper atmosphere (20–160 km). The key products are wind, temperature and density. If selected, this mission could provide new insights into vertical coupling in the atmosphere and could help improve weather and climate models. We conducted simulation studies to assess the measurement performances in the altitude range 60–110 km, with a special focus on the geomagnetic effects.

Polarimetry has been established as an enhancement to classical photometry in aerosol remote sensing over the past years. We propose a fast and exact radiometric and polarimetric calibration method for polarized photometers. Additionally, a technique for correcting an alt-azimuthal mount is introduced. These methods are applied to measurements obtained with our SSARA instrument during the A-LIFE field campaign. For 2 d, the data are subjected to an inversion of aerosol optical properties.

We describe a new spectrometer for quantification of HONO and NO₂ in ambient air, called HODOR. The instrument uses an LED and two highly reflective mirrors to increase the effective optical absorption path to ~6 km. The accuracy of concentration retrievals was validated using parallel measurements by a single wavelength cavity ring-down spectrometer of laboratory-generated gas mixtures. The instrument's precision suffices for quantification of HONO and NO₂ in an urban environment.

This study presents a novel ammonia retrieval system we developed GOSAT. This system was used to derive estimates of global atmospheric ammonia concentrations between 2009 and 2014. The results demonstrated significantly high concentrations stemming from six anthropogenic emission source areas and four biomass burning ones. Their horizontal and temporal distributions were compared with those from IASI. They were totally consistent and the causes of the differences were discussed.

The current instruments being used for weather forecasting and climate require accurate radiative transfer codes to process the acquired data. In addition the codes are becoming more realistic, as they can now account for the effects of cloud and aerosols, rather than only simulating radiances for a clear sky. We describe a fast, accurate, and general purpose code that we have developed to help model data from these instruments.

Ground-based measurements of emissions from oil and natural gas production are important for understanding emission distributions and improving emission inventories. Here, measurement technique Other Test Method 33A (OTM 33A) is validated through several test releases staged at the Methane Emissions Technology Evaluation Center. These tests suggest OTM 33A has no inherent bias and that a group of OTM measurements is within 5 % of the known mean emission rate.

The development of GPS station networks that provide rich data sources containing atmospheric information will enable more GPS applications in the field of meteorology. This study describes a genetic algorithm for the water vapour tomography; overcomes the ill-conditioned problem; and eliminates the reliance on excessive constraints, priori information, and external data. It is proven in the paper that accurate 3-D water vapour distribution can be provided by this study for atmospheric research.