We evaluated spectra from a scanning spectrometer network for the monitoring of volcanic gas emissions using a modelled background spectrum. Statistical methods were applied in order to improve the quality of the spectroscopic evaluation. We used this technique to assess the robustness of standard retrievals at two volcanos: Nevado del Ruiz (Colombia) and Tungurahua (Ecuador).

The research presented in this work involves field data analysis, numerical modelling techniques and approaches to a long-standing problem of liquid precipitation measurements: the sampling and the interpretation of the tipping-bucket sensor signal. The present study shows relevant implications of the adopted data processing methods for the accuracy of the rainfall intensity measurements provided by traditional tipping-bucket gauges.

We describe a novel method of measuring the exchange of carbon dioxide over croplands using a high-altitude balloon (HAB). Our methodology uses two balloon launches on a single day to measure atmospheric changes in carbon dioxide and then relate them to the photosynthesis and respiration of the crops. Our results are compared to satellite measures of greenness and a research site in Bondville, Illinois. A future goal is to recruit citizen scientists to perform the launches.

To capture complicated CO₂ distribution at the volcanic crater of Solfatara (Italy), a 2-D map of volcanic CO₂ distribution has been inverted from path-integrated measurements. It is in agreement with independent measurements and confirms an area of anomalous CO₂ degassing along the eastern edge and the center of the crater. The method may have important implications for measurements of degassing features that can only be accessed from limited angles, e.g. airborne sensing of volcanic plumes.

Launch of INSAT-3D carrying a multi-spectral imager by the ISRO made it possible to obtain profiles of temperature and water vapour over India with higher temporal and vertical resolutions. Initial validation is made with the radiosonde, other satellites and reanalysis data sets. Good correlation between INSAT-3D and in situ measurements is noticed with a few cautions. Temperature data from INSAT-3D are of high quality and can be directly assimilated for better forecasts over India.

This study evaluates the performance of the recently developed Pandora spectrometer by comparing it with the Brewer reference triad. The instrument random uncertainty, total column ozone temperature dependence, and ozone air mass dependence have been determined using two Pandora and six Brewer instruments. In general, Pandora and Brewer instruments both have very low random uncertainty and air mass dependence. However, the Brewer has smaller ozone temperature dependence than Pandora.

In this manuscript, the effect of ambient RH and T on HCHO measurements by PTR-MS was investigated, and the Poly 2-D regression was found to be a good nonlinear surface simulation of R (RH, T) for correcting measured HCHO concentration. Intercomparisons between PTR-MS and other OVOC and VOC measuring techniques were conducted through a field study in urban roadside areas of Hong Kong primarily, and good agreements were found between these different techniques.

This study validates version 3.5 of the ACE-FTS NOy species data sets by comparing diurnally scaled ACE-FTS data to correlative data from 11 other satellite limb sounders. For all five species examined (NO, NO₂, HNO₃, N₂O₅, and ClONO₂), there is good agreement between ACE-FTS and the other data sets in various regions of the atmosphere. In these validated regions, these NO_y data products can be used for further investigation into the composition, dynamics, and climate of the stratosphere.

Boundary-layer pressurised balloons allow for horizontal multi-day flights in the lower atmosphere, carrying light scientific payloads. Ozonesondes, usually used for balloon soundings have too short a lifetime for such flights. An adaptation is proposed, whereby conventional sondes are operated with short measurement phases alternating with longer periods of dormancy. The sondes were operated over the western Mediterranean, offering an original perspective on tropospheric ozone.

Turbulence measurements are important to boundary layer meteorology and related fields. Doppler lidars are capable of providing continuous profiles of turbulence statistics. Herein, the most direct turbulence measurement, vertical velocity variance, is validated with those from sonic anemometers. Spectra are also compared. A method of calculating velocity variance using the autocovariance is shown to improve the accuracy of the measurement by mitigating effects of noise and averaging.

We introduce a strategy for the measurement of CO₂ in the stratosphere. We use an orbiting limb sounder to measure both the thermal infrared (TIR) and far-infrared (FIR) atmospheric emissions. The rotational transitions of O₂ in the FIR are exploited to derive the temperature and pressure fields that are needed to retrieve the CO₂ from its spectrum in the TIR. The proposed experiment can determine two-dimensional distributions of the CO2 with precision of 1 ppm at altitudes between 10 and 50 km.

A research–level retrieval algorithm for cloud optical and microphysical properties is developed for the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) aboard the Terra satellite. This yields reliable estimates of important cloud variables at a horizontal resolution of 30 m. Comparisons of the ASTER retrieval results with the operational cloud products from the Moderate Resolution Imaging Spectroradiometer (MODIS) show a high agreement for 48 example cloud fields.

When this study started, its goal was to provide a reanalysis of the stratospheric composition of methane and nitrous oxide, two important sources of hydrogen and nitrogen species in the stratosphere that influence the ozone abundance. However, the goal changed when several issues in the assimilated observations were discovered. Finally, this study illustrates how data assimilation methods can be used to add value to the observations as well as to diagnose their limitations.

A meteorological balloon-borne cloud sensor called the cloud particle sensor (CPS) has been developed. The CPS can count the number of particles per second and can obtain the cloud phase information (i.e. liquid, ice, or mixed). Twenty-five test flights have been made between 2012 and 2015 at midlatitude and tropical sites. The results from the four flights are discussed.

Ecosystem flux networks measure carbon dioxide and water vapor exchange and are integral to global studies of the biosphere and climate change. Yet recent evidence suggests a measurement error in sonic anemometry, the principal instrument for eddy-covariance research. A novel Bayesian analysis estimates the three-dimensional correction in these instruments and demonstrates that 60 % of the sites within the AmeriFlux network and numerous others globally underestimate all ecosystem fluxes by 8–12 %.

In this paper a SWIR airglow imager is presented. It is especially designed for the observation of small-scale gravity waves and turbulence features in the OH airglow layer with a high spatio-temporal resolution of up to 17 m (at mesopause heights) and 2.5 to 2.8 s. Two case studies show small-scale wave structures with horizontal wavelengths of approximately 550 m as well as vortex formation and decomposition of wave fronts, both indicating the onset of turbulence.

The recent dramatic development of multi-GNSS constellations brings great opportunities and potential for more enhanced precise positioning, navigation, timing, and other applications. In this contribution, we develop a numerical weather model (NWM) constrained PPP processing system to improve the multi-GNSS precise positioning. Compared to the standard PPP solution, significant improvements of both convergence time and positioning accuracy are achieved with the NWM-constrained PPP solution.

This paper focuses on the demonstration and assessment of thermal infrared laser heterodyne spectro-radiometry for the remote sensing of carbon dioxide (CO₂). A research instrument has been developed and operated from the ground using direct sunlight to measure CO₂ to a high precision. This technology would enable the development of high-performance miniature ground-based sounders to complement existing measurement networks and contribute to the improvement of global carbon emission assessment.

Aerosols play an important role in the Earth's climate. One of the main aerosol properties is the single scattering albedo which is a measure of the aerosol absorption. In this work we have presented a method to retrieve this aerosol property in the ultraviolet and we presented the results for measurements at the urban environment of Athens, Greece. We show that the spectral dependence of the aerosol absorption in the VIS–IR and the UV range depends on the aerosol composition and type.

We explore algorithms of estimating spectral flux over the entire longwave spectrum solely from hyperspectral radiance observations using AIRS data as an example. This is different from the traditional approach of estimating broadband flux from satellite observations in two ways: (1) no other remote sensing data sets are needed, and (2) the spectral details of the broadband flux can be derived. This study shows that the hyperspectral radiances can be used to directly obtain spectral flux.

We present a spectral imager capable of measuring the 2-D distribution of NO₂ above well-delimited emission sources (power plant, city, etc.) with an unprecedent spatiotemporal resolution. Tests at a coal-fired power plant demonstrated its capability to observe dynamic processes such as the conversion from NO to NO₂ in the early plume. Potential applications are pollution sources monitoring, reactive plume chemistry models validation, ships and volcanic emissions tracking, etc.

The Ozone Monitoring Instrument (OMI) on board the NASA EOS Aura satellite monitors the concentrations of trace gases. The accuracy of such observations relies partly on information on clouds. The OMI OMCLDO2 product derives the cloud fraction and pressure from the observed radiance in the visible. This paper reports on an improved version of this product. Compared to the previous version, the changes in cloud fraction are very small, but the changes in the cloud pressure can be significant.

We present global distributions of CO₂ concentrations in the upper atmosphere (70–140 km) derived from high-resolution 4.3 µm MIPAS spectra from 2005 to 2012. CO₂ relative abundances have been measured at 120–140 km for the first time. The data have an unprecedented accuracy. CO₂ shows a strong seasonal behaviour. CO₂ largely controls the temperature of the upper atmosphere and its measurement is very important for understanding the impact of climate change in this region.

Here we reported the development of a PTR-ID-CIMS to investigate industry-related emissions of VOCs in the Yangtze River Delta (YRD) region, the largest economic zone in China. We observed strong primary HCHO emissions from the industrial zone that overwhelmed local HCHO secondary formation. These primary HCHO sources can potentially lead to severe local and regional air pollution formation. Therefore, primary industrial HCHO emissions should be strictly monitored and regulated in this region.

The SP-AMS exhibited a different sensitivity to black carbon vs. potassium as more SOA mass was condensed onto biomass burning particles. The SP-AMS's sensitivity to BC mass did not plateau following successive SOA coatings, despite achieving high OA : BC mass ratios > 9. A laser ablation single-particle mass spectrometer exhibited a positive correlation to the condensed SOA mass on individual soot particles, demonstrating its ability to obtain mass quantitative measurements from complex matrices.