A five-channel fluorescence lidar was developed for the study of atmospheric aerosol. The fluorescence spectrum induced by 355 nm laser emission is analyzed in five spectral intervals, namely 438 and 29, 472 and 32, 513 and 29, 560 and 40, and 614 and 54 nm. This lidar system was operated during strong forest fires. Our results demonstrate that, for urban aerosol, the maximal fluorescence backscattering is observed at 472 nm, while for smoke, the spectrum is shifted toward longer wavelengths.

Multi-angle polarimetric measurements have been shown to greatly improve the remote sensing capability of aerosols and help atmospheric correction for ocean color retrievals. However, the uncertainty correlations among different measurement angles have not been well characterized. In this work, we provided a practical framework to evaluate the impact of the angular uncertainty correlation in retrieval results and a method to directly estimate correlation strength from retrieval residuals.

We present an evaluation of current retrieval techniques in the ice phase applied to polarimetric radar measurements with collocated in situ observations of aircraft conducted over the Olympic Mountains, Washington State, during winter 2015. Radar estimates of ice properties agreed most with aircraft observations in regions with pronounced radar signatures, but uncertainties were identified that indicate issues of some retrievals, particularly in warmer temperature regimes.

With its near-real-time observations and good horizontal coverage, the Infrared Atmospheric Sounding Interferometer (IASI) instrument can contribute to the monitoring systems for a systematic and continuous detection of exceptional atmospheric events such as fires, anthropogenic pollution episodes, volcanic eruptions, or industrial releases. In this paper, a new approach is described for the detection and characterization of unexpected events in terms of trace gases using IASI radiance spectra.

This work demonstrates the viability of a remote sensing technique using nanosatellites to measure stratospheric temperature. This measurement technique can probe the stratosphere and mesosphere at a fine vertical scale around the globe unlike other high-altitude measurement techniques, which would provide an opportunity to observe atmospheric gravity waves and turbulence. We analyze observations from two satellite platforms to provide a proof of concept and characterize measurement uncertainty.

This paper provides insights into the effects of clouds on Orbiting Carbon Observatory (OCO-2) measurements of CO₂. Calculations are carried out that indicate the extent to which this satellite experiment underestimates CO₂, due to these cloud effects, as a function of the distance between the surface observation footprint and the nearest cloud. The paper discusses how to lessen the influence of these cloud effects.

New global nitric oxide (NO) volume-mixing-ratio and lower-thermospheric temperature data products, retrieved from Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) spectra with the IMK-IAA MIPAS data processor, have been released. The dataset covers the entire Envisat mission lifetime and includes retrieval results from all MIPAS observation modes. The data are based on ESA version 8 calibration and were processed using an improved retrieval approach.

In this paper, we used a random forest model to fill the observation gaps of the fluxes measured during 2015–2019. We found that the net radiation was the most important input variable. And we justified the reliability of the model. Further, it was revealed that the model performed better after relative humidity was removed from the input. Lastly, we compared the results of the model with those of three other machine learning models, and we found that the model outperformed all of them.

A network of low-cost sensors is a good alternative to improve the detection of fugitive CH₄ emissions. We present the results of four tests conducted with two types of Figaro sensors that were assembled on four chambers in a laboratory experiment: a comparison of five models to reconstruct the CH₄ signal, a strategy to reduce the training set size, a detection of age effects in the sensors and a test of the capability to transfer a model between chambers for the same type of sensor.

Four-year TROPOMI observations are used to derive tropospheric NO₂ emissions in two mega(cities) with high anthropogenic activity. Wind-assigned anomalies are calculated, and the emission rates and spatial patterns are estimated based on a machine learning algorithm. The results are in reasonable agreement with previous studies and the inventory. Our method is quite robust and can be used as a simple method to estimate the emissions of NO₂ as well as other gases in other regions.

We successfully developed the first pseudorandom modulation continuous-wave narrowband sodium lidar (PMCW-NSL) system for simultaneous measurements of the mesopause region's temperature and wind. Based on the innovative decoded technique and algorithm for CW lidar, both the main and residual lights modulated by M-code are used and directed to the atmosphere in the vertical and eastward directions, tilted 20° from the zenith. The PMCW-NSL system can applied to airborne and space-borne purposes.

The Brewer ozone spectrophotometer is one of the World Meteorological Organization (WMO) Global Atmosphere Watch (GAW)'s standard ozone monitoring instruments since the 1980s. This work is aimed at obtaining answers to (1) why Brewer primary calibration work can only be performed at certain sites (e.g., Izaña and MLO) and (2) what is needed to assure the equivalence of calibration quality from different sites.

This paper describes how measurements from a small uncrewed aircraft system can be used to estimate the vertical turbulent heat energy exchange between different layers in the atmosphere. This is particularly important for the atmosphere in the Arctic, as turbulent exchange in this region is often suppressed but is still important to understand how the atmosphere interacts with sea ice. We present three case studies from the MOSAiC field campaign in Arctic sea ice in 2020.