European pollution outbreaks during ACE 2: Optical particle properties inferred from multiwavelength lidar and star-Sun photometry

(1) On the basis of multiwavelength backscatter and 532-nm extinction profiling with lidar at Sagres (37� N, 9� W), southern Portugal, and optical depth observations with a star photometer at the lidar site and a Sun photometer atop a nearby mountain, several European pollution outbreaks were characterized during the Second Aerosol Characterization Experiment (ACE 2) in the summer of 1997. A sophisticated analysis scheme applied to the lidar-photometer data set is described. The observations are mainly presented in terms of profiles of the 532-nm extinction-to-backscatter ratio (lidar ratio) and of A u ngstrom exponents calculated for the wavelength ranges 400-532 nm and 532-800 nm. The lidar ratio indicates the aerosol type (marine, soil, pollution) whereas the A u ngstrom exponents are sensitive to changes in the particle size distribution (accumulation mode, coarse mode). Results of an extensive correlation analysis considering all determined optical parameters, relative humidity, and measurement height are discussed. Finally, the spectrally resolved optical depth and the column A u ngstrom exponents for the lofted outbreak plumes determined from the lidar profiles are compared with respective values derived from the star and Sun photometer measurements. INDEX TERMS: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801); 0345 Atmospheric Composition and Structure: Pollution— urban and regional (0305); 0365 Atmospheric Composition and Structure: Troposphere—composition and chemistry; 0368 Atmospheric Composition and Structure: Troposphere—constituent transport and chemistry; 1630 Global Change: Impact phenomena; KEYWORDS: multiwavelength lidar, star photometer, Sun photometer, anthropogenic aerosols, aerosol optical properties

[1]  S. H. Melfi,et al.  Raman lidar measurements of aerosol extinction and backscattering. 1. Methods and comparisons , 1998 .

[2]  J. Ackermann.  The Extinction-to-Backscatter Ratio of Tropospheric Aerosol: A Numerical Study , 1998 .

[3]  M. Mishchenko,et al.  Modeling phase functions for dustlike tropospheric aerosols using a shape mixture of randomly oriented polydisperse spheroids , 1997 .

[4]  S. H. Melfi,et al.  OBSERVATION OF RAMAN SCATTERING BY WATER VAPOR IN THE ATMOSPHERE , 1969 .

[5]  A. Ansmann,et al.  Independent measurement of extinction and backscatter profiles in cirrus clouds by using a combined Raman elastic-backscatter lidar. , 1992, Applied optics.

[6]  A. Ansmann,et al.  An intercomparison of aerosol light extinction and 180° backscatter as derived using in situ instruments and Raman lidar during the INDOEX field campaign , 2002 .

[7]  S. Kinne,et al.  Aerosol-induced radiative flux changes off the United States mid-Atlantic coast: Comparison of values calculated from sunphotometer and in situ data with those measured by airborne pyranometer , 1999 .

[8]  Mark J. Rood,et al.  In situ measurement of the aerosol extinction‐to‐backscatter ratio at a polluted continental site , 2000 .

[9]  Jacques Pelon,et al.  Study of the moist Convective Boundary Layer structure by backscattering lidar , 1994 .

[10]  Yoram J. Kaufman,et al.  Interannual variation of ambient aerosol characteristics on the east coast of the United States , 1999 .

[11]  H. Jonsson,et al.  Influence of humidity on the aerosol scattering coefficient and its effect on the upwelling radiance during ACE-2 , 2000 .

[12]  Sundar A. Christopher,et al.  Use of the Ångstrom exponent to estimate the variability of optical and physical properties of aging smoke particles in Brazil , 1999 .

[13]  David M. Winker.  Global Observations of Aerosols and Clouds from Combined Lidar and Passive Instruments to Improve Radiation Budget and Climate Studies , 1999 .

[14]  A. Ansmann,et al.  Lindenberg Aerosol Characterization Experiment 1998 (LACE 98): Overview , 2002 .

[15]  Lidar network observations of cirrus morphological and scattering properties during the International Cirrus Experiment 1989 : the 18 October 1989 case study and statistical analysis , 1993 .

[16]  Y Sasano,et al.  Tropospheric aerosol optical properties derived from lidar, sun photometer, and optical particle counter measurements. , 1994, Applied optics.

[17]  A new star photometer developed for spectral aerosol optical thickness measurements in Lindenberg , 1995 .

[18]  J. Heintzenberg,et al.  Aerosol Optical properties at Sagres, Portugal during ACE‐2 , 2000 .

[19]  J. Cooney,et al.  Measurements Separating the Gaseous and Aerosol Components of Laser Atmospheric Backscatter , 1969, Nature.

[20]  Y. Kaufman,et al.  Dynamic aerosol model: Urban/industrial aerosol , 1998 .

[21]  J. Notholt,et al.  Continuous day and night aerosol optical depth observations in the Arctic between 1991 and 1999 , 2002 .

[22]  V. D. Galkin,et al.  Water vapor column content and optical depths measurements by a sun- and starphotometer , 1998 .

[23]  Irina N. Sokolik,et al.  Influence of the aerosol vertical distribution on the retrievals of aerosol optical depth from satellite radiance measurements , 2000 .

[24]  Robert Frouin,et al.  Airborne lidar measurements of aerosol spatial distribution and optical properties over the Atlantic Ocean during a European pollution outbreak of ACE-2 , 2000 .

[25]  Philip B. Russell,et al.  An overview of the ACE-2 clear sky column closure experiment (CLEARCOLUMN) , 2000 .

[26]  S H Melfi,et al.  Remote measurements of the atmosphere using Raman scattering. , 1972, Applied optics.

[27]  A. Ansmann,et al.  Measurement of atmospheric aerosol extinction profiles with a Raman lidar. , 1990, Optics letters.

[28]  Measurements of the spectral optical depth of aerosols with moon and star light during polar night 1994/95 and 1995/96 in Ny-Ålesund, Spitsbergen , 1997 .

[29]  A. Ansmann,et al.  European pollution outbreaks during ACE 2: Lofted aerosol plumes observed with Raman lidar at the Portuguese coast , 2001 .

[30]  Y. Kaufman,et al.  Passive remote sensing of tropospheric aerosol and atmospheric , 1997 .

[31]  Albert Ansmann,et al.  Vertical profiling of optical and physical particle properties over the tropical Indian Ocean with six‐wavelength lidar: 2. Case studies , 2001 .

[32]  A. Ansmann,et al.  Experimental determination of the lidar overlap profile with Raman lidar. , 2002, Applied optics.

[33]  Y. Sasano,et al.  Error caused by using a constant extinction/backscattering ratio in the lidar solution. , 1985, Applied optics.

[34]  Albert Ansmann,et al.  European pollution outbreaks during ACE 2: Microphysical particle properties and single-scattering albedo inferred from multiwavelength lidar observations , 2002 .

[35]  A. Cacciari,et al.  Spectral measurements of aerosol particle extinction in the 0.4–3.7 μm wavelength range, performed at Sagres with the IR‐RAD sun‐radiometer , 2000 .

[36]  T. Eck,et al.  An emerging ground-based aerosol climatology: Aerosol optical depth from AERONET , 2001 .

[37]  Kengo Iokibe,et al.  Ground‐based network observation of Asian dust events of April 1998 in east Asia , 2001 .

[38]  M. Wendisch,et al.  Variability of aerosol optical parameters by advective processes , 1994 .

[39]  Albert Ansmann,et al.  Scanning 6-Wavelength 11-Channel Aerosol Lidar , 2000 .

[40]  A Comparison of the Aerosol Thickness Derived from Ground-Based and Airborne Measurements , 2000 .

[41]  Peter V. Hobbs,et al.  Humidification factors for atmospheric aerosols off the mid‐Atlantic coast of the United States , 1999 .

[42]  J. Klett.  Stable analytical inversion solution for processing lidar returns. , 1981, Applied optics.

[43]  Irina N. Sokolik,et al.  Radiative heating rates and direct radiative forcing by mineral dust in cloudy atmospheric conditions , 2000 .

[44]  J. Haywood,et al.  Multi‐spectral calculations of the direct radiative forcing of tropospheric sulphate and soot aerosols using a column model , 1997 .

[45]  Gian Paolo Gobbi,et al.  Lidar estimation of tropospheric aerosol extinction, surface area and volume: Maritime and desert-dust cases , 2001 .

[46]  F. G. Fernald.  Analysis of atmospheric lidar observations: some comments. , 1984, Applied optics.