Case study of Raman lidar measurements of Asian dust events in 2000 and 2001 at Nagoya and Tsukuba, Japan

Sakai, Tetsu; Shibata, Takashi; Iwasaka, Yasunobu; Nagai, Tomohiro; Nakazato, Masahisa; Matsumura, Takatsugu; Ichiki, Akinori; Kim, Yoon-Suk; Tamura, Koichi; Troshkin, D. N.; Hamdi, Saipul

doi:10.1016/s1352-2310(02)00664-7

Cited by 78 publications

(75 citation statements)

References 43 publications

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“…The values of d a,coarse were calculated from the OPC data using the T-matrix method, and were almost constant (21.9 $ 22.4%) over the height range of the measurement because the shape of the size distribution in that mode was almost constant (Figure 10). These values are somewhat smaller than the previously reported maximum values ($25%) measured in the Asian dust layer over Japan [Sakai et al, 2000[Sakai et al, , 2002Murayama, 2002].…”

Section: Total Aerosol Linear Depolarization Ratiocontrasting

confidence: 65%

“…This was because we had difficulty in calibrating the signal at around 30 km due to the low signal-to-noise ratio at that height in this experiment. In the calculation of the backscattering ratio, the aerosol extinction at the Mie/Rayleigh wavelength (532 nm) was estimated from the aerosol extinction coefficient, s a (z), derived using the Raman oxygen signals at 375.4 nm, assuming the relationship s a (z) / l Àk(z) [Sakai et al, 2002]. The wavelength exponent (k) is assumed to be 1.0 when a > 1 or zero when a 1.…”

Section: Raman Lidar Measurementsmentioning

confidence: 99%

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Raman lidar and aircraft measurements of tropospheric aerosol particles during the Asian dust event over central Japan: Case study on 23 April 1996

et al. 2003

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[1] The vertical distributions of tropospheric aerosol properties were measured during the Asian dust event over central Japan (35°-36°N, 136°-137°E), using a ground-based Raman lidar and aircraft-based instruments on 23 April 1996. The lidar measured enhancements of aerosol backscattering below an altitude of 4 km and between 5 and 8 km where the total aerosol linear depolarization ratio showed peaks of 12-15% and the relative humidities were $30%. The aircraft measurements showed that the aerosol particles consisted primarily of irregularly shaped mineral dusts and sea salts with a mode radius (r m ) of $1 mm and sulfates with r m $ 0.1 mm over the measured height range of 0.6-5.5 km. Electron microscopic analyses suggest that $77% of the mineral particles were coated with a solution at 1.8 km and that the fraction of coated particles decreased with height. The aerosol backscattering coefficients (b a ), calculated from the airborne optical particle counter (OPC) data, were smaller than the lidar-derived values by $30% above 3.1 km and by $44% below that altitude. The difference was attributable to the horizontal and temporal inhomogeneities of the aerosol properties between the measurement sites and to the uncertainty in b a , particularly for the coarse particles calculated from the OPC data. The aerosol depolarization ratios (d a ) estimated from the OPC data showed the same increase as those obtained with the lidar above 4.1 km. This suggests that the proportion of backscattering by coarse particles to total particles primarily controlled the d a measured with the lidar in that region.

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Section: Total Aerosol Linear Depolarization Ratiocontrasting

confidence: 65%

Section: Raman Lidar Measurementsmentioning

confidence: 99%

Raman lidar and aircraft measurements of tropospheric aerosol particles during the Asian dust event over central Japan: Case study on 23 April 1996

et al. 2003

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“…In another ground-based LIDAR study in Japan, Sakai et al (2004) describe measurements of ice production at the margins of a dry and depolarizing airmass that originated over the Gobi desert (Sakai et al, 2002); ice appears to have been first produced at ∼7.5 km altitude with RH i near or just over 100% and the temperature at the top of the ice cloud layer at ∼−35 • C, which just falls into our WARM HET cloud region (v), being too warm for the homogeneous freezing of pure water droplets and background sulphate solution droplets. The authors present evidence that moisture for the ice production was supplied by the intersection of the dry dust layer with a warm conveyor belt.…”

Section: Discussionmentioning

confidence: 99%

The potential influence of Asian and African mineral dust on ice, mixed-phase and liquid water clouds

Wiacek

Peter²,

Lohmann³

2010

Atmos. Chem. Phys.

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Abstract. This modelling study explores the availability of mineral dust particles as ice nuclei for interactions with ice, mixed-phase and liquid water clouds, also tracking the particles' history of cloud-processing. We performed 61 320 oneweek forward trajectory calculations originating near the surface of major dust emitting regions in Africa and Asia using high-resolution meteorological analysis fields for the year 2007. Dust-bearing trajectories were assumed to be those coinciding with known dust emission seasons, without explicitly modelling dust emission and deposition processes. We found that dust emissions from Asian deserts lead to a higher potential for interactions with high ice clouds, despite being the climatologically much smaller dust emission source. This is due to Asian regions experiencing significantly more ascent than African regions, with strongest ascent in the Asian Taklimakan desert at ∼25%, ∼40% and 10% of trajectories ascending to 300 hPa in spring, summer and fall, respectively. The specific humidity at each trajectory's starting point was transported in a Lagrangian manner and relative humidities with respect to water and ice were calculated in 6-h steps downstream, allowing us to estimate the formation of liquid, mixed-phase and ice clouds. Downstream of the investigated dust sources, practically none of the simulated air parcels reached conditions of homogeneous ice nucleation (T − 40 • C) along trajectories that have not experienced water saturation first. By far the largest fraction of cloud forming trajectories entered conditions of mixed-phase clouds, where mineral dust will potentially exert the biggest influence. The majority of trajectories also passed through atmospheric regions supersaturated with respect to ice but Correspondence to: A. Wiacek (aldona.wiacek@dal.ca) subsaturated with respect to water, where so-called "warm ice clouds" (T − 40 • C) theoretically may form prior to supercooled water or mixed-phase clouds. The importance of "warm ice clouds" and the general influence of dust in the mixed-phase cloud region are highly uncertain due to both a considerable scatter in recent laboratory data from ice nucleation experiments, which we briefly review in this work, and due to uncertainties in sub-grid scale vertical transport processes unresolved by the present trajectory analysis. For "classical" cirrus-forming temperatures (T −40 • C), our results show that only mineral dust ice nuclei that underwent mixed-phase cloud-processing, most likely acquiring coatings of organic or inorganic material, are likely to be relevant. While the potential paucity of deposition ice nuclei shown in this work dimishes the possibility of deposition nucleation, the absence of liquid water droplets at T −40 • C makes the less explored contact freezing mechanism (involving droplet collisions with bare ice nuclei) highly inefficient. These factors together indicate the necessity of further systematic studies of immersion mode ice nucleation on mineral dust suspended in atmospherically rel...

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“…Sakai et al (2002) reported an average lidar ratio value of 46 ± 5 sr obtained by Raman lidar measurements at 0.532 μm, for an elevated dust layer over Tsukuba, on April 23. Studying Asian dust events in 1998 and 1999, using a high spectral resolution lidar and a combined Raman elastic-backscatter lidar, Liu et al (2002) reported height-averaged values of 42-55 sr at two sites in Japan.…”

Section: Dust Layermentioning

confidence: 98%

Aerosol Properties Computed from Aircraft-Based Observations During the ACE-Asia Campaign: 2. A Case Study of Lidar Ratio Closure

Kuzmanoski

Box

Schmid

et al. 2007

Aerosol Science and Technology

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For a vertical profile with three distinct layers (marine boundary, pollution, and dust layers), observed during the ACE-Asia campaign, we carried out a comparison between the modeled lidar ratio vertical profile and that obtained from co-located airborne NASA AATS-14 sunphotometer and shipborne Micro-Pulse Lidar (MPL) measurements. The vertically resolved lidar ratio was calculated from two size distribution vertical profiles-one obtained by inversion of sunphotometer-derived extinction spectra, and one measured in-situ-combined with the same refractive index model based on aerosol chemical composition. The aerosol model implies single scattering albedos of 0.78-0.81 and 0.93-0.96 at 0.523 μm (the wavelength of the lidar measurements), in the pollution and dust layers, respectively. The lidar ratios calculated from the two size distribution profiles agree closely in the dust layer; they are however, significantly lower than the lidar ratios derived from combined lidar and sunphotometer measurements. Uncertainties in aerosol size distributions and refractive index only partly explain these differences, suggesting that particle nonsphericity in this layer is an additional explanation. In the pollution layer, the two size distribution profiles yield lidar ratios that agree within the MPLNET is funded by the NASA Earth Observing System and Radiation Sciences Program. We would like to thank Jens Redemann for his detailed review of an earlier version of the manuscript and helpful comments. We would also like to thank the anonymous reviewers for their valuable comments and suggestions.Address correspondence to M. Kuzmanoski, School of Physics, University of New South Wales, Sydney, NSW 2052, Australia. E-mail: mkuzm@phys.unsw.edu.au estimated uncertainties. The retrieved size distributions result in a lidar ratio which is in closer agreement with that derived from lidar/sunphotometer measurements in this layer, with still large differences at certain altitudes (the largest relative difference was 46%). We explain these differences by non-uniqueness of the result of the size distribution retrieval, by a lack of information on the mixing state of particles, and the vertical variability of the particle refractive index.

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Case study of Raman lidar measurements of Asian dust events in 2000 and 2001 at Nagoya and Tsukuba, Japan

Cited by 78 publications

References 43 publications

Raman lidar and aircraft measurements of tropospheric aerosol particles during the Asian dust event over central Japan: Case study on 23 April 1996

Raman lidar and aircraft measurements of tropospheric aerosol particles during the Asian dust event over central Japan: Case study on 23 April 1996

The potential influence of Asian and African mineral dust on ice, mixed-phase and liquid water clouds

Aerosol Properties Computed from Aircraft-Based Observations During the ACE-Asia Campaign: 2. A Case Study of Lidar Ratio Closure

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