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Investigating apparent aerosol effects on precipitation in climate model simulations
Aerosols in the atmosphere serve as condensation nuclei for the cloud formation. This brings an important influence on the microphysical properties of cloud water that in turn affect the processes in the formation of precipitation. Aerosol-cloud-precipitation interaction which simultaneously change cloud albedo interest many studies to find out aerosol impact on precipitation formation. The studies were done by observation measurement and simulation. UK Met Office Unified Model (UM) is one model that includes aerosol direct and indirect effect in the NWP configuration which leads to study aero ...
GOES-R ABI: Next Generation Satellite Imaging
This extension of the COMET lesson “GOES-R: Benefits of Next Generation Environmental Monitoring” focuses on the ABI instrument, the satellite's 16-channel imager. With increased spectral coverage, greater spatial resolution, more frequent imaging, and improved image pixel geolocation and radiometric performance, the ABI will bring significant advancements to forecasting, numerical weather prediction, and climate and environmental monitoring. The first part of the lesson introduces the ABI's key features and improvements over earlier GOES imagers. The second section lets users interactively ex ...
GAW Report, 207. Recommendations for a Composite Surface-Based Aerosol Network
Suspended particulate matter in the atmosphere, commonly known as aerosol by the technical and scientific community, plays a role in climate change, air quality/human health, ozone depletion and the long-range transport and deposition of toxics and nutrients. Aerosols have many sources ranging from sea spray and mineral dust that are mechanically generated by wind at the Earth’s surface to sulphates, nitrates and organics produced primarily by chemical reaction of gases in the atmosphere producing non-volatile products that condense to form particles. In addition, semi-volatile substances such ...
Seasonal variability in the optical properties of Baltic aerosols
A five-year dataset of spectral aerosol optical thickness was used to analyse the seasonal variability of aerosol optical properties (the aerosol optical thickness (AOT) at wavelength λ=500 nm, AOT(500) and the Ångström exponent for the 440-870 nm spectral range, α(440, 870)) over the Baltic Sea and dependence of these optical properties on meteorological factors (wind direction, wind speed and relative humidity). The data from the Gotland station of the global radiometric network AERONET (Aerosol Robotic Network, http://aeronet.gsfc.nasa.gov) were taken to be representative of the Baltic Sea ...
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Evaluation of the accuracy of analysis tools for atmospheric new particle formation
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 7. Korhonen H.; Sihto S.-L.; Kerminen V.-M.; et al. - Copernicus GmbH, 2011Several mathematical tools have been developed in recent years to analyze new particle formation rates and to estimate nucleation rates and mechanisms at sub-3 nm sizes from atmospheric aerosol data. Here we evaluate these analysis tools using 1239 numerical nucleation events for which the nucleation mechanism and formation rates were known exactly. The accuracy of the estimates of particle formation rate at 3 nm (J3) showed significant sensitivity to the details of the analysis, i.e. form of equations used and assumptions made about the initial size of nucleating clusters, with the fraction o ...
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Analysis of number size distributions of tropical free tropospheric aerosol particles observed at Pico Espejo (4765 m a.s.l.), Venezuela
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 7. Schmeissner T.; Krejci R.; Ström J.; et al. - Copernicus GmbH, 2011The first long-term measurements of aerosol number and size distributions in South-American tropical free troposphere (FT) were performed from March 2007 until March 2009. The measurements took place at the high altitude Atmospheric Research Station Alexander von Humboldt. The station is located on top of the Sierra Nevada mountain ridge at 4765 m a.s.l. nearby the city of Mérida, Venezuela. Aerosol size distribution and number concentration data was obtained with a custom-built Differential Mobility Particle Sizer (DMPS) system and a Condensational Particle Counter (CPC). The analysis of the ...
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Microphysical and radiative effects of aerosols on warm clouds during the Amazon biomass burning season as observed by MODIS: impacts of water vapor and land cover
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 7. Ten Hoeve J.E.; Remer L.A.; Jacobson M.Z. - Copernicus GmbH, 2011Aerosol, cloud, water vapor, and temperature profile data from the Moderate Resolution Imaging Spectroradiometer (MODIS) are utilized to examine the impact of aerosols on clouds during the Amazonian biomass burning season in Rondônia, Brazil. It is found that increasing background column water vapor (CWV) throughout this transition season between the Amazon dry and wet seasons likely exerts a strong effect on cloud properties. As a result, proper analysis of aerosol-cloud relationships requires that data be stratified by CWV to account better for the influence of background meteorological vari ...
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A two-dimensional volatility basis set: 1. organic-aerosol mixing thermodynamics
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 7. Donahue N.M.; Epstein S.A.; Pandis S.N.; et al. - Copernicus GmbH, 2011We develop the thermodynamic underpinnings of a two-dimensional volatility basis set (2D-VBS) employing saturation mass concentration (Co) and the oxygen content (O:C) to describe volatility, mixing thermodynamics, and chemical evolution of organic aerosol. The work addresses a simple question: "Can we reasonably constrain organic-aerosol composition in the atmosphere based on only two measurable organic properties, volatility and the extent of oxygenation?" This is an extension of our earlier one-dimensional approach employing volatility only (C* = γ Co, where γ is an activity coefficient). U ...
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On the potential contribution of open lead particle emissions to the central Arctic aerosol concentration
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 7. Held A.; Brooks I.M.; Leck C.; et al. - Copernicus GmbH, 2011We present direct eddy covariance measurements of aerosol number fluxes, dominated by sub-50 nm particles, at the edge of an ice floe drifting in the central Arctic Ocean. The measurements were made during the ice-breaker borne ASCOS (Arctic Summer Cloud Ocean Study) expedition in August 2008 between 2°–10° W longitude and 87°–87.5° N latitude. The median aerosol transfer velocities over different surface types (open water leads, ice ridges, snow and ice surfaces) ranged from 0.27 to 0.68 mm s−1 during deposition-dominated episodes. Emission periods were observed more frequently over the open ...
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Global distribution of sea salt aerosols: new constraints from in situ and remote sensing observations
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 7. Jaeglé L.; Quinn P.K.; Bates T.S.; et al. - Copernicus GmbH, 2011We combine in situ measurements of sea salt aerosols (SS) from open ocean cruises and ground-based stations together with aerosol optical depth (AOD) observations from MODIS and AERONET, and the GEOS-Chem global chemical transport model to provide new constraints on SS emissions over the world's oceans. We find that the GEOS-Chem model using the Gong (2003) source function overestimates cruise observations of coarse mode SS mass concentrations by factors of 2–3 at high wind speeds over the cold waters of the Southern, North Pacific and North Atlantic Oceans. Furthermore, the model systematical ...
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The effect of meteorological and chemical factors on the agreement between observations and predictions of fine aerosol composition in southwestern Ontario during BAQS-Met
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 7. Markovic M.Z.; Hayden K.L.; Murphy J.G.; et al. - Copernicus GmbH, 2011The Border Air Quality and Meteorology Study (BAQS-Met) was an intensive, collaborative field campaign during the summer of 2007 that investigated the effects of transboundary pollution, local pollution, and local meteorology on air quality in southwestern Ontario. This analysis focuses on the measurements of the inorganic constituents of particulate matter with diameter of less than 1 μm (PM1), with a specific emphasis on nitrate. We evaluate the ability of AURAMS, Environment Canada's chemical transport model, to represent regional air pollution in SW Ontario by comparing modelled aerosol in ...
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