Published under the terms of the Creative Commons Attribution-Noncommercial 3.0 Unported LicenseVertical profiles of the linear particle depolarization ratio of pure dust clouds were measured during the Saharan Mineral Dust Experiment (SAMUM) at Ouarzazate, Morocco (30.9 degrees N, -6.9 degrees E), close to source regions in May-June 2006, with four lidar systems at four wavelengths (355, 532, 710 and 1064 nm). The intercomparison of the lidar systems is accompanied by a discussion of the different calibration methods, including a new, advanced method, and a detailed error analysis. Over the whole SAMUM periode pure dust layers show a mean linear particle depolarization ratio at 532 nm of 0.31, in the range between 0.27 and 0.35, with a mean angstrom ngstrom exponent (AE, 440-870 nm) of 0.18 (range 0.04-0.34) and still high mean linear particle depolarization ratio between 0.21 and 0.25 during periods with aerosol optical thickness less than 0.1, with a mean AE of 0.76 (range 0.65-1.00), which represents a negative correlation of the linear particle depolarization ratio with the AE. A slight decrease of the linear particle depolarization ratio with wavelength was found between 532 and 1064 nm from 0.31 +/- 0.03 to 0.27 +/- 0.04
T E L L U SCharacterization of Saharan dust, marine aerosols and mixtures of biomass-burning aerosols and dust by means of multi-wavelength depolarization and Raman lidar measurements during SAMUM 2 A B S T R A C T The particle linear depolarization ratio δ p of Saharan dust, marine aerosols and mixtures of biomass-burning aerosols from southern West Africa and Saharan dust was determined at three wavelengths with three lidar systems during the SAharan Mineral dUst experiMent 2 at the airport of Praia, Cape Verde, between 22 January and 9 February 2008. The lidar ratio S p of these major types of tropospheric aerosols was analysed at two wavelengths. For Saharan dust, we find wavelength dependent mean particle linear depolarization ratios δ p of 0.24-0.27 at 355 nm, 0.29-0.31 at 532 nm and 0.36-0.40 at 710 nm, and wavelength independent mean lidar ratios S p of 48-70 sr. Mixtures of biomass-burning aerosols and dust show wavelength independent values of δ p and S p between 0.12-0.23 and 57-98 sr, respectively. The mean values of marine aerosols range independent of wavelength for δ p from 0.01 to 0.03 and for S p from 14 to 24 sr.
MIPAS-B2 is a balloon-borne limb-emission sounder for atmospheric research. The heart of the instrument is a Fourier spectrometer that covers the mid-infrared spectral range (4-14 microns) and operates at cryogenic temperatures. Essential for this application is the sophisticated line-of-sight stabilization system, which is based on an inertial navigation system and is supplemented with an additional star reference system. The major scientific benefit of the instrument is the simultaneous detection of complete trace gas families in the stratosphere without restrictions concerning the time of day and viewing directions. The specifications, the design considerations, the actual realization of the instrument, and the results of characterization measurements that have been performed are described.
[1] On 4 days in summer and winter the mixing layer height over the municipal area of Munich, Germany, was determined by several remote sensing instruments and in situ probes. The main motivation was to obtain information on aerosols, and therefore we decided to understand the mixing layer as that layer where most of the locally produced aerosols are concentrated. In this paper we wanted to investigate the potential of the quite different methodologies which depend on measurements of aerosol properties and those which do not. The operation of two lidars, a ceilometer, a wind-temperatureradar, a sodar, radiosondes, and aerosol probes onboard of a microlight aircraft allowed such a thorough intercomparison. As the instruments were located at different sites, the horizontal homogeneity of the mixing layer could also be observed. It was found that the agreement between the different methodologies is very good as long as the mixing layer height does not exceed approximately 1 km, which is the common measurement range of all instruments. In summer, however, the mixing layer can reach 2 km and more, so that the lidar turns out to be the most capable remote sensing technique. Another advantage of the lidar is the possibility to clearly derive the internal structure of the mixing layer. The latter is important in cases when simple parameterizations assume vertical homogeneity of aerosol properties within the mixing layer. On the other hand, lidars are quite expensive and require a trained operator. As a conclusion, the development of unattended working lidars including automated data evaluation should be fostered. From the limited data set it was found that the mixing layer height in Munich did not change more than approximately 100 m over a horizontal distance of around 50 km. If this finding can be confirmed by further measurements, the area of Munich is a good test bed for the validation of aerosol retrievals from satellite data with medium spatial resolution and for the validation of the numerical treatment of aerosols in mesoscale chemistry transport models.
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