- UHRA Home
- Browsing by Author
Browsing by Author "Centre for Atmospheric and Climate Physics Research"
Now showing items 241-260 of 432
-
Modelling diffraction by facetted particles
Hesse, Evelyn; Macke, Andreas; Havemann, Stephan; Baran, Anthony; Ulanowski, Zbigniew; Kaye, Paul H. (2012-01-23)A method to approximate azimuthally resolved light scattering patterns and phase functions due to diffraction and external reflection by strongly absorbing facetted particles is demonstrated for a cube and compared with ... -
Modelling diffraction during ray-tracing using the concept of energy flow lines
Hesse, E. (2008)The ray tracing with diffraction on facets (RTDF) model is suitable for rapid computation of scattering on faceted dielectric objects such as ice crystals. It combines ray tracing with diffraction on flat facets. The model ... -
Modelling light scattering by absorbing smooth and slightly rough facetted particles
Hesse, Evelyn; Collier, C. T.; Penttilä, Antti; Nousiainen, Timo; Ulanowski, Joseph; Kaye, Paul H. (2015-05)A method for approximating light scattering properties of strongly absorbing facetted particles which are large compared to the wavelength is presented. It consists in adding the approximated external diffraction and ... -
Modelling light scattering by rough particles and particulate layers using RTDF
Hesse, Evelyn; Collier, Christopher Thomas; Goldstone, Mica; Ulanowski, Joseph; Kaye, Paul H. (2013-06-20)Computations of light-scattering properties for non-axisymmetric particles based on exact methods like the T-matrix [1] and discrete dipole approximation (DDA) [2] have upper size parameter limits of applicability, depending ... -
Modelling the dispersion of particle numbers in five European cities
Kukkonen, J.; Karl, M.; Keuken, M. P.; Denier van der Gon, H. A. C.; Denby, B. R.; Singh, Vikas; Douros, J.; Manders, A.; Samaras, Z.; Moussiopoulos, N.; Jonkers, S.; Aarnio, M.; Karppinen, A.; Kangas, L.; Lützenkirchen, S.; Petaja, T.; Vouitsis, I.; Sokhi, Ranjeet (2016-02-04)We present an overview of the modelling of particle number concentrations (PNCs) in five major European cities, namely Helsinki, Oslo, London, Rotterdam, and Athens, in 2008. Novel emission inventories of particle numbers ... -
Monitoring and modelling of NO2 and fine particles for urban air quality management
Sokhi, Ranjeet; Bualert, S.; Luhana, L.; Tremper, A.H.; Burton, Agneta (2000-09) -
Monitoring dust particle orientation with measurements of sunlight dichroic extinction
Daskalopoulou, V.; Raptis, I.P; Tsekeri, Alexandra; Amiridis, Vassilis; Kazadzis, S.; Ulanowski, Zbigniew; Metallinos , S.; Tassis, K.; Martin, Bill (2021-09-29)Alignment of irregularly shaped dust aerosols leading to linear dichroism has been reported in atmospheric layers. The present study intents to quantify the excess linear polarization of direct solar radiation propagating ... -
Multi-wavelength Raman lidar, sun photometric and aircraft measurements in combination with inversion models for the estimation of the aerosol optical and physico-chemical properties over Athens, Greece
Mamouri, R. E.; Papayannis, A.; Amiridis, V.; Mueller, D.; Kokkalis, P.; Rapsomanikis, S.; Karageorgos, E. T.; Tsaknakis, G.; Nenes, A.; Kazadzis, S.; Remoundaki, E. (2012)A novel procedure has been developed to retrieve, simultaneously, the optical, microphysical and chemical properties of tropospheric aerosols with a multi-wavelength Raman lidar system in the troposphere over an urban site ... -
Multiobjective Optimization Applied to the Eradication of Persistent Pathogens
Steuernagel, O.; Polani, D. (2010)In scenarios such as therapeutic modeling or pest control, one aims to suppress infective agents or maximize crop yields while minimizing the side-effects of interventions, such as cost, environmental impact, and toxicity. ... -
Multiwavelength Raman lidar observations of particle growth during long-range transport of forest-fire smoke in the free troposphere
Mueller, D.; Mattis, I.; Ansmann, A.; Wandinger, U.; Ritter, C.; Kaiser, D. (2007-03-02)We present particle effective radii and Angstrom exponents of aged free-tropospheric forest-fire smoke. The particle plumes were observed with different multiwavelength Raman lidars downwind of the fires that burned in ... -
Multiyear aerosol observations with dual-wavelength Raman lidar in the framework of EARLINET
Mattis, I.; Ansmann, A.; Mueller, D.; Wandinger, U.; Althausen, D. (2004-07-10)For the first time, a Raman lidar operating simultaneously in the ultraviolet (UV) and in the visible wavelength range was employed to measure vertical profiles of volume extinction coefficients of particles at 355 and 532 ... -
Nanoparticles in urban air : A very small problem
Price, Heather; Jones, Tim; BeruBe, Kelly; Matthews, Ian; Arthur, Robert (Inst of Environment & Health, Cranfield University, 2008)The human body is exposed to atmospheric pollutants on a daily basis. Breathing is the most effective route of airborne contaminant entry into the human body (BéruBé́ et al., 2008), meaning our lungs and airways take the ... -
New algorithms and their application for satellite remote sensing of surface PM2.5 and aerosol absorption
Hu, R-M.; Sokhi, R.S.; Fisher, B. (2009)Estimation of Particulate Matter (PM) concentration and aerosol absorption is very important in air quality and climate studies. To date, smoke, mineral dust and anthropogenic pollutants are the most uncertain aerosol ... -
New Directions : Understanding interactions of air quality and climate change at regional scales
Alapaty, Kiran; Mathur, Rohit; Pleim, Jonathan; Hogrefe, Christian; Rao, S. Trivikrama; Ramaswamy, Venkatachalam; Galmarini, Stefano; Schaap, Martijn; Makar, Paul; Vautard, Robert; Baklanov, Alexander; Kallos, George; Vogel, Bernhard; Sokhi, Ranjeet (2012-03)The estimates of the short-lived climate forcers’ (SLCFs) impacts and mitigation effects on the radiation balance have large uncertainty because the current global model set-ups and simulations contain simplified ... -
A new method to retrieve the real part of the equivalent refractive index of atmospheric aerosols
Vratolis, S.; Fetfatzis, P.; Argyrouli, A.; Papayannis, A.; Müller, D.; Veselovskii, I.; Bougiatioti, A.; Nenes, A.; Remoundaki, E.; Diapouli, E.; Manousakas, M.; Mylonaki, M.; Eleftheriadis, K. (2018-03-01)In the context of the international experimental campaign Hygroscopic Aerosols to Cloud Droplets (HygrA-CD, 15 May to 22 June 2014), dry aerosol size distributions were measured at Demokritos station (DEM) using a Scanning ... -
A New Outlook on Ice Cloud through Sub-Millimetre-Wave Scattering
Baran, Anthony; Havemann, Stephan; Fox, Stuart; Harlow, Chawn; Thelen, Jean-Claude; Hesse, Evelyn; Sourdeval, Odran; Ishimoto, Hiroshi; Bower, Keith; O'Shea, Sebastian (2018-07-10)Scattering by atmospheric ice at sub-mm-wave frequencies is a challenge to both the cloud physics and light scattering communities owing to scattering at these frequencies being dependent on assumptions about the particle ... -
A new waveguide switch/modulator for integrated optics
Martin, William Eugene (1975)A waveguide optical switch and/or modulator device is described that uses a single-mode waveguide version of the Mach-Zehnder interferometer. A mode selective branching waveguide is used for switching, and modulation can ... -
Nonlinear effects on pulsed laser propagation in the atmosphere
Martin, Bill; Winfield, R.J. (1988-02)Nonlinear effects on the propagation of a high power pulsed laser beam through the earth’s atmosphere are modeled. Stimulated Raman scattering in relatively modest power laser beams is estimated to be very significant when ... -
Observations of small ice in mixed phase clouds using and airborne SID2 Small Ice Detector
Barrett, Paul; Blyth, Alan; Brown, Phil; Ulanowski, Zbigniew (2015-04-12)Here we present observations of small ice crystals in mixed phase cloud systems using an aircraft mounted SID2 (Small Ice Detector 2) probe. It is likely that these small ice particles have formed through an immersion ... -
Observations of fluorescent and biological aerosol at a high-altitude site in Central France
Gabey, A.; Vaitilingom, M; Freney, E.; Boulon, J.; Sellegri, K.; Gallagher, M.W.; Crawford, I.P.; Robinson, Niall; Stanley, Warren; Kaye, Paul H. (2013-03-27)Total bacteria, fungal spore and yeast counts were compared with UV Light-Induced Fluorescence (UV-LIF) measurements of ambient aerosol at the summit of the Puy de Dˆome (pdD) mountain in Central France (1465 ma.s.l), which ...