Evaluation of hierarchical agglomerative cluster analysis methods for discrimination of primary biological aerosol
Summary: HCA analysis methods were evaluated for the purpose of identifying primary biological aerosol sampled with a WIBS. The ward linkage with z-score normalisation could discriminate between five test particles with 98% accuracy. We applied these methods to a previously studied ambient data set, where both methods produced similar results with some minor differences in cluster partitioning. Finally we compared to previous approaches and found our new method offered improved quantification of PBA.
Atmos. Meas. Tech., 8, 4979-4991, doi:10.5194/amt-8-4979-2015, 2015
Evaluation of the operational Aerosol Layer Height retrieval algorithm for Sentinel-5 Precursor: application to O2 A band observations from GOME-2A
Atmos. Meas. Tech., 8, 4947-4977, doi:10.5194/amt-8-4947-2015, 2015
Impact of cloud horizontal inhomogeneity and directional sampling on the retrieval of cloud droplet size by the POLDER instrument
Summary: The cloud droplet size retrieval of POLDER is accurate even when the measurements are limited. The algorithm can be improved by (1) including the measurements in the primary rainbow region to provide accurate large droplet (>15 µm) retrievals; (2) performing higher-resolution retrieval (42 km × 42 km) to ensure more successful retrievals and reduce the bias introduced by cloud horizontal inhomogeneity.
Atmos. Meas. Tech., 8, 4931-4945, doi:10.5194/amt-8-4931-2015, 2015
Sensitivity of remotely sensed trace gas concentrations to polarisation
Summary: We investigate the sensitivity to polarisation of geoCARB, a proposed geostationary mission to measure column-averaged concentrations of CO2, CH4 and CO from spectra of reflected sunlight, through analysis of an ensemble of simulated polarised spectra for targets in India, China and Australia. Although geoCARB will not carry polarisers or polarisation scramblers, we show that the effects of polarisation can be minimised provided the polarisation signature of geoCARB is calibrated before flight.
Atmos. Meas. Tech., 8, 4917-4930, doi:10.5194/amt-8-4917-2015, 2015
EARLINET Single Calculus Chain – overview on methodology and strategy
Atmos. Meas. Tech., 8, 4891-4916, doi:10.5194/amt-8-4891-2015, 2015
HOx radical chemistry in oxidation flow reactors with low-pressure mercury lamps systematically examined by modeling
Atmos. Meas. Tech., 8, 4863-4890, doi:10.5194/amt-8-4863-2015, 2015
An enhanced procedure for measuring organic acids and methyl esters in PM2.5
Summary: We have developed an enhanced solid-phase extraction pretreatment procedure to organic acids separated from methyl esters in fine aerosol. This procedure prevents the fatty acids and dimethyl phthalate from being overestimated. Furthermore, five polycyclic aromatic hydrocarbon acids were quantified, and correlations between the PAH-acids and tracer dicarboxylic and aromatic acids indicated that they came from primary or/and secondary emissions.
Atmos. Meas. Tech., 8, 4851-4862, doi:10.5194/amt-8-4851-2015, 2015
OMI total column ozone: extending the long-term data record
Summary: Comparisons show that ozone measured by OMI varied less than 1% relative to other NASA and European satellite instruments or relative to ground-based instruments. This means that OMI data can be used to reliably track global changes in ozone during the expected ozone recovery period and can be used to look for ozone signatures related to climate change.
Atmos. Meas. Tech., 8, 4845-4850, doi:10.5194/amt-8-4845-2015, 2015
Radiometric consistency assessment of hyperspectral infrared sounders
Summary: The radiometric and spectral consistency among the Atmospheric Infrared Sounder (AIRS), the Infrared Atmospheric Sounding Interferometer (IASI), and the Cross-track Infrared Sounder (CrIS) is fundamental for the creation of long-term infrared hyperspectral radiance benchmark data sets for both intercalibration and climate-related studies. In this study, the CrIS radiance measurements are directly compared with IASI on MetOp-A and MetOp-B and AIRS on Aqua.
Atmos. Meas. Tech., 8, 4831-4844, doi:10.5194/amt-8-4831-2015, 2015
Simulated retrievals for the remote sensing of CO2, CH4, CO, and H2O from geostationary orbit
Summary: The Geostationary Fourier Transform Spectrometer (GeoFTS) is designed to measure high-resolution spectra of reflected sunlight in near-infrared bands and to deliver simultaneous retrievals of column-averaged dry air mole fractions of CO2, CH4, CO, and H2O at different times of day. We perform radiative transfer simulations over both clear-sky and all-sky scenes and estimate the prospective performance of retrievals based on results from Bayesian error analysis and characterization.
Atmos. Meas. Tech., 8, 4817-4830, doi:10.5194/amt-8-4817-2015, 2015
Characterization of trace metals on soot aerosol particles with the SP-AMS: detection and quantification
Summary: The purpose of this study was to develop a method for the quantification of trace metal content in black carbon aerosol in real time, such as combustion-related emissions, by using the SP-AMS. The properties of 13 different trace metals (Na, Al, Ca, V, Cr, Fe, Mn, Ni, Cu, Zn, Rb, Sr and Ba) were investigated in a controlled laboratory experiment. The results from the laboratory tests were applied to study fine particles in emissions of a heavy-fuel-oil-fired heating station.
Atmos. Meas. Tech., 8, 4803-4815, doi:10.5194/amt-8-4803-2015, 2015
Assessing 5 years of GOSAT Proxy XCH4 data and associated uncertainties
Summary: Atmospheric CH4 is an important greenhouse gas. Long-term global observations are necessary to understand its behaviour, with satellite observations playing a key role. The "proxy" retrieval method is one of the most successful but relies on the contribution from atmospheric CO2 models. This work assesses the significance of the uncertainty from the model CO2 within the retrieval and determines that despite this uncertainty the data are still valuable for determining sources and sinks of CH4.
Atmos. Meas. Tech., 8, 4785-4801, doi:10.5194/amt-8-4785-2015, 2015
An improved method for retrieving nighttime aerosol optical thickness from the VIIRS Day/Night Band
Summary: Using Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB) data, a new method is developed for retrieving nighttime aerosol optical thickness values through the examination of the dispersion of radiance values above an artificial light source. Preliminary results suggest that artificial light sources can be used for estimating regional and global nighttime aerosol distributions in the future.
Atmos. Meas. Tech., 8, 4773-4783, doi:10.5194/amt-8-4773-2015, 2015
Spectral aerosol extinction (SpEx): a new instrument for in situ ambient aerosol extinction measurements across the UV/visible wavelength range
Summary: We describe a new instrument developed to observe ambient atmospheric aerosol extinction spectra from 300 to 700nm. Laboratory tests were performed to demonstrate that the instrument compares well with theoretical calculations over that spectral range, as well as with commercially available instrumentation measuring aerosol extinction at three visible wavelengths. The unique spectral data will be used to explore linkages between ambient aerosol optical properties, chemistry, and microphysics.
Atmos. Meas. Tech., 8, 4755-4771, doi:10.5194/amt-8-4755-2015, 2015
High-resolution measurements from the airborne Atmospheric Nitrogen Dioxide Imager (ANDI)
Summary: An airborne spectrometer was used to produce a high spatial resolution (80 x 20 m) map of nitrogen dioxide over Leicester City (UK) and the surrounding countryside. Clear local hotspots due to traffic, industrial activity and power generation are observable, as are comparative reductions over parks and rural areas. A positive temporal gradient was also observed over the 2-hour flight, possibly indicating traffic build-up over time.
Atmos. Meas. Tech., 8, 4735-4754, doi:10.5194/amt-8-4735-2015, 2015
Geostationary Emission Explorer for Europe (G3E): mission concept and initial performance assessment
Summary: The Geostationary Emission Explorer for Europe (G3E) is a mission concept for a greenhouse gas sounder in geostationary orbit. It is designed to provide column-average concentrations of carbon dioxide, methane, and carbon monoxide with high spatial and 2-hour temporal resolution throughout the central European continent. The prospective data density, precision and accuracy suggest G3E as a key component of a future carbon emission monitoring system.
Atmos. Meas. Tech., 8, 4719-4734, doi:10.5194/amt-8-4719-2015, 2015
Known and unknown unknowns: uncertainty estimation in satellite remote sensing
Summary: Clear communication of the uncertainty on data is necessary for users to make appropriate use of it. This paper discusses the representation of uncertainty in satellite observations of the environment, arguing that the dominant sources of error are assumptions made during data analysis. The resulting uncertainty may be more usefully represented using ensemble techniques (a set of analyses using different assumptions to illustrate their impact) than with traditional statistical metrics.
Atmos. Meas. Tech., 8, 4699-4718, doi:10.5194/amt-8-4699-2015, 2015
Characterization of Mediterranean hail-bearing storms using an operational polarimetric X-band radar
Summary: This work shows the effective monitoring of intense precipitation events in the Mediterranean area by an operational X-band dual-polarization radar operated in south Italy by the Department of Civil Protection. Two severe hail-bearing storms, causing high attenuation, have been described in terms of the polarimetric radar signatures and estimated rainfall fields. The comparative analysis of the radar observations enabled the triggering hail formation and precipitation process to be inferred.
Atmos. Meas. Tech., 8, 4681-4698, doi:10.5194/amt-8-4681-2015, 2015
An automated cloud detection method based on the green channel of total-sky visible images
Atmos. Meas. Tech., 8, 4671-4679, doi:10.5194/amt-8-4671-2015, 2015
Methane and nitrous oxide retrievals from MIPAS-ENVISAT
Summary: We present our revised CH4 and N2O profiles derived from MIPAS-ENVISAT spectra, which are now available for the entire measurement period. We describe the retrieval of the profiles and discuss the improvements compared to earlier versions and their effect on the mixing ratios. We analyse the averaging kernels and the resolution of the profiles. An error discussion for both gases is given.
Atmos. Meas. Tech., 8, 4657-4670, doi:10.5194/amt-8-4657-2015, 2015