Showing papers by "Aleksander Pietruczuk published in 2008"

Systematic lidar observations of Saharan dust over Europe in the frame of EARLINET (2000-2002)

Abstract: [1] More than 130 observation days of the horizontal and vertical extent of Saharan dust intrusions over Europe during the period May 2000 to December 2002 were studied by means of a coordinated lidar network in the frame of the European Aerosol Research Lidar Network (EARLINET). The number of dust events was greatest in late spring, summer, and early autumn periods, mainly in southern (S) and southeastern (SE) Europe. Multiple aerosol dust layers of variable thickness (300–7500 m) were observed. The center of mass of these layers was located in altitudes between 850 and 8000 m. However, the mean thickness of the dust layer typically stayed around 1500–3400 m and the corresponding mean center of mass ranged from 2500 to 6000 m. In exceptional cases, dust aerosols reached northwestern (NW), northern (N), or northeastern (NE) Europe, penetrating the geographical area located between 4°W–28°E (longitude) and 38°N–58°N (latitude). Mean aerosol optical depths (AOD), extinction-to-backscatter ratios (lidar ratios, LR), and linear depolarization ratios of desert aerosols ranged from 0.1 to 0.25 at the wavelength of 355 or 351 nm, 30 to 80 sr at 355 or 351 nm, and 10 to 25% at 532 nm, respectively, within the lofted dust plumes. In these plumes typical Saharan dust backscatter coefficients ranged from 0.5 to 2 Mm−1sr−1. Southern European stations presented higher variability of the LR values and the backscatter-related Angstrom exponent values (BRAE) (LR: 20–100 sr; BRAE: −0.5 to 3) than northern ones (LR: 30–80 sr; BRAE: −0.5 to 1).

The European Aerosol Research Lidar Network (EARLINET): An Overview

Abstract: The European Aerosol Research LIdar NETwork (EARLINET) is the first aerosol lidar network on a continental scale with the main goal to provide a comprehensive, quantitative, and statistically significant database for the aerosol distribution over Europe. Next, we present EARLINET along with the main network activities.

Global Solar Radiation and Direct Aerosol Forcing at Belsk, Poland

Abstract: A comparison of global solar radiation fluxes at the bottom of the atmosphere and Direct Aerosol Radiative Forcing (DARF) values determined by two different methods is presented. Analysis of data covers the period from 2002 to 2005. Global solar radiation fluxes and DARF obtained at the Geophysical Observatory at Belsk by means of CM11 pyranometer are compared with fluxes and DARF calculated for Belsk AERONET station by radiation transfer model. Aerosol microphysical properties retrieved from almucantar measurements taken by Cimel CE318A Sun-sky scanning radiometer are used in the radiation transfer model. The analysis of fluxes of global solar radiation at the bottom of the atmosphere indicates that the average difference between data taken by the two methods is about 2%. Besides, 95% of cases are within 10% interval of differences, and 84% of cases are within 5%. In the case of DARF, the agreement of results taken by the two methods is much worse. The average percentage difference between DARF values calculated on the basis of measurements taken by the two methods is about 20%. Besides, only 20% of cases are within 10% interval of differences and 29% of cases are within 20%. In both cases, values obtained from pyranometric measurements are lower than the values from radiometric measurements.