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Mamouri R.E.,Cyprus University of Technology | Ansmann A.,Leibniz Institute for Tropospheric Research
Atmospheric Chemistry and Physics | Year: 2015

A lidar method is presented that permits the estimation of height profiles of ice nuclei concentrations (INC) in desert dust layers. The polarization lidar technique is applied to separate dust and non-dust backscatter and extinction coefficients. The desert dust extinction coefficients σd are then converted to aerosol particle number concentrations APC280 which consider particles with radius > 280 nm only. By using profiles of APC280 and ambient temperature T along the laser beam, the profile of INC can be estimated within a factor of 3 by means of APC-T-INC parameterizations from the literature. The observed close relationship between σd at 500 nm and APC280 is of key importance for a successful INC retrieval. We studied this link by means of AERONET (Aerosol Robotic Network) sun/sky photometer observations at Morocco, Cabo Verde, Barbados, and Cyprus during desert dust outbreaks. The new INC retrieval method is applied to lidar observations of dust layers with the spaceborne lidar CALIOP (Cloud Aerosol Lidar with Orthogonal Polarization) during two overpasses over the EARLINET (European Aerosol Research Lidar Network) lidar site of the Cyprus University of Technology (CUT), Limassol (34.7° N, 33° E), Cyprus. The good agreement between the CALIOP and CUT lidar retrievals of σd, APC280, and INC profiles corroborates the potential of CALIOP to provide 3-D global desert dust APC280 and INC data sets. © Author(s) 2015. Source

Mamouri R.E.,Cyprus University of Technology | Ansmann A.,Leibniz Institute for Tropospheric Research
Atmospheric Measurement Techniques | Year: 2014

The polarization-lidar photometer networking (POLIPHON) method for separating dust and non-dust aerosol backscatter and extinction, volume, and mass concentration is extended to allow for a height-resolved separation of fine-mode and coarse-mode dust properties in addition. The method is applied to a period with complex aerosol layering of fine-mode background dust from Turkey and Arabian desert dust from Syria. The observation was performed at the combined European Aerosol Research Lidar Network (EARLINET) and Aerosol Robotic Network (AERONET) site of Limassol (34.7° N, 33° E), Cyprus, in September 2011. The dust profiling methodology and case studies are presented. Consistency between the column-integrated optical properties obtained with sun'sky photometer and the respective results derived by means of the new lidar-based method corroborate the applicability of the extended POLIPHON version. © Author(s) 2014. CC Attribution 3.0 License. Source

Heintzenberg J.,Leibniz Institute for Tropospheric Research
International Journal of Global Warming | Year: 2012

The complexity of the atmospheric aerosol and its connection with clouds and climate are illustrated with a host of examples against the background of our present limited state of understanding. A discussion of related feedbacks demonstrates the difficulties of resolving all respective research issues. The key role of aerosols and clouds in anthropogenic climate change make the high uncertainties related to them ever more painful. Nevertheless, there are suggestions to manipulate aerosols and clouds by climate engineering to counteract global warming. Before considering such remedies the aerosol-cloud-climate conundrum needs to be reduced to a level of uncertainty that is comparable to those related to anthropogenic greenhouse gases. Considering the complexity of the aerosol/ cloud system the challenge will be to identify the necessary essential knowledge and differentiate that from marginal details and focus research efforts on these essentials in order to simplify the complex aerosol-cloud system without loosing indispensable features. Copyright © 2012 Inderscience Enterprises Ltd. Source

Heintzenberg J.,Leibniz Institute for Tropospheric Research | Leck C.,University of Stockholm
Atmospheric Chemistry and Physics | Year: 2012

In the course of global warming dramatic changes are taking place in the Arctic and boreal environments. However, physical aerosol data in from the central summer Arctic taken over the course of 18 yr from 1991 to 2008 do not show systematic year-to-year changes, albeit substantial interannual variations. Besides the limited extent of the data several causes may be responsible for these findings. The processes controlling concentrations and particle size distribution of the aerosol over the central Arctic perennial pack ice area, north of 80°, may not have changed substantially during this time. Environmental changes are still mainly effective in the marginal ice zone, the ice-free waters and continental rims and have not propagated significantly into the central Arctic yet where they could affect the local aerosol and its sources. The analysis of meteorological conditions of the four expedition summers reveal substantial variations which we see as main causes of the measured variations in aerosol parameters. With combined lognormal fits of the hourly number size distributions of the four expeditions representative mode parameters for the summer aerosol in the central Arctic have been calculated. The combined aerosol statistics discussed in the present paper provide comprehensive physical data on the summer aerosol in the central Arctic. These data are the only surface aerosol information from this region. © 2012 Author(s). Source

Horn S.,Leibniz Institute for Tropospheric Research
Geoscientific Model Development | Year: 2012

In this work the three dimensional compressible moist atmospheric model ASAMgpu is presented. The calculations are done using graphics processing units (GPUs). To ensure platform independence OpenGL and GLSL are used, with that the model runs on any hardware supporting fragment shaders. The MPICH2 library enables interprocess communication allowing the usage of more than one GPU through domain decomposition. Time integration is done with an explicit three step Runge-Kutta scheme with a time-splitting algorithm for the acoustic waves. The results for four test cases are shown in this paper. A rising dry heat bubble, a cold bubble induced density flow, a rising moist heat bubble in a saturated environment, and a DYCOMS-II case. © Author(s) 2012. Source

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