Saharan Mineral Dust Experiments SAMUM–1 and SAMUM–2: what have we learned?

Ansmann, Albert; Petzold, A.; Kandler, Konrad; Tegen, Ina; Wendisch, Manfred; Müller, Detlef; Weinzierl, Bernadett; Müller, Thomas; Heintzenberg, Jost

doi:10.3402/tellusb.v63i4.16236

Cited by 89 publications

(129 citation statements)

References 110 publications

(257 reference statements)

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“…Redelsperger et al, 2006), and Saharan Mineral Dust Experiment (SAMUM) (e.g. Heintzenberg et al, 2009;Ansmann et al, 2011), etc. By using the capabilities of various lidars, dust profiling (e.g.…”

Section: Resultsmentioning

confidence: 99%

“…Dust is mostly composed of water-insoluble minerals and shows nearly complete hydrophobicity or at least poor hygroscopicity (e.g. Twomey, 1977;Li-Jones et al, 1998;Kaaden et al, 2009;Schladitz et al, 2011;Ansmann et al, 2011). However, after being lifted in the air and mixed/coated with water-soluble materials such as sea-salt, sulfate, or nitrate by atmospheric processing (Levin et al, 1996;Yin et al, 2002), dust hygroscopicity can increase, which can cause changes in optical properties.…”

Section: Introductionmentioning

confidence: 99%

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CALIPSO observations of transatlantic dust: vertical stratification and effect of clouds

et al. 2012

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Abstract. We use CALIOP nighttime measurements of lidar backscatter, color and depolarization ratios, as well as particulate retrievals during the summer of 2007 to study transatlantic dust properties downwind of Saharan sources, and to examine the influence of nearby clouds on dust. Our analysis suggests that (1) under clear skies, while lidar backscatter and color ratio do not change much with altitude and longitude in the Saharan Air Layer (SAL), depolarization ratio increases with altitude and decreases westward in the SAL; (2) the vertical lapse rate of dust depolarization ratio, introduced here, increases within SAL as plumes move westward; (3) nearby clouds barely affect the backscatter and color ratio of dust volumes within SAL but not so below SAL. Moreover, the presence of nearby clouds tends to decrease the depolarization of dust volumes within SAL. Finally, (4) the odds of CALIOP finding dust below SAL next to clouds are about 2/3 of those far away from clouds. This feature, together with an apparent increase in depolarization ratio near clouds, indicates that particles in some dust volumes loose asphericity in the humid air near clouds, and cannot be identified by CALIPSO as dust.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

CALIPSO observations of transatlantic dust: vertical stratification and effect of clouds

et al. 2012

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“…its chemical (DeAngelis and Gaudichet, 1991;Lequy et al, 2013), micro-physical and optical properties (Collaud Coen et al, 2004;Müller et al, 2011). See Ansmann et al (2011) and references therein. Indicators proposed for aged SD are firstly high abundance of Ca 2þ combined with low H þ -concentration and a K þ /Na þ ratio larger than 2 (Wagenbach et al, 1996).…”

Section: Identification Of Sd By Multi-factorial Indexmentioning

confidence: 98%

Identification and monitoring of Saharan dust: An inventory representative for south Germany since 1997

Flentje

Briel

Beck

et al. 2015

Atmospheric Environment

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h i g h l i g h t sLarge Ca 2þ abundance and coarse particle volume (0.5e7 mm) indicate Saharan dust.The annual number of Saharan dust days shows no significant trend. The relative contribution of dust to total particle mass decreases from 6% to 4%. Sahara dust events, detected by different metrics at different stations, are consistent. 4 of 5 EU law threshold exceedances (daily PM10 > 50 mg/m 3 ) are due to Saharan dust. a b s t r a c t An inventory of Sahara dust (SD) events at the Hohenpeibenberg Global Atmosphere Watch station (Germany) is presented for the period 1997e2013. Based on daily in-situ measurements, high Ca 2þ -ion concentrations and large particle volume concentrations at diameters d p z 0.5e7 mm are inferred as indicators for days influenced by SD. The resulting SD catalogue agrees with SD time series from Schneefernerhaus, Augsburg and Jungfraujoch stations. On average, SD occurs in 5e15 SD events (SDE) per year covering about 10e60 days/yr in the mixing layer. SDE exhibit a clear seasonality with spring and early autumn maxima, and typically last for 1e3 days. SDE are equally frequent but more significant at Alpine levels due to lower background. Wet deposition of Ca 2þ at the surface is little correlated (R 2 ¼ 0.14) with particle Ca 2þ on a daily basis and yields an average annual Ca 2þ immission of 0.22 ± 0.04 g/m 2 yr, about 40% of which is due to SD. The majority of outstanding weekly Fe and Al depositions are associated with SDE. SD contributes about 0.5 ± 0.1 mg/m 3 to the total particle mass with a decreasing trend from 6% to 4% (À0.1%/yr) in the 1997e2013 period. Except from one, all threshold exceedances according to European legislation (daily PM 10 > 50 mg/m 3 ) at Hohenpeibenberg are due to SD. Implications are discussed with respect to SD-related circulation patterns, SD-induced temperature anomalies in weather forecast models and the capability of aerosol models to capture SDE.

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“…Thus, observations of the linear depolarization ratio at several wavelengths were taken into account in the Saharan Mineral Dust Experiment (SAMUM-1 and SAMUM-2). According to these observation, they studied the chemical/mineralogical, microphysical and optical properties of dust and typical biomass burning aerosol layers [22] .…”

mentioning

confidence: 99%

Research in depolarization of particles in Tibetan Plateau and coastal area by lidar

Dai

Song

et al. 2014

SPIE Proceedings

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Vertical profiles of the linear particle depolarization ratio p δ of cloud and aerosol in the Tibet Plateau were measured during the Tibetan Plateau atmospheric expedition experiment campaign with water vapor, cloud and aerosol lidar system, which is capable of depolarization ratio measurement. The atmospheric comprehensive observations were performed during July of 2013 at Litang (30.03°N,100.28°E), which is 3949 meters above the mean sea level, Sichuan province, China. It was the first time to detect and obtain the Tibetan Plateau cloud and aerosol lidar depolarization profiles to our knowledge. After completing the plateau experiment campaign, the lidar system measured the atmosphere above coastal area in Qingdao (36.165°N,120.4956°E). In this year, we continued to participate in the plateau experiment campaign in Nagchu (31.5°N,92.05°E), which is 4600 meters above the mean sea level, The Tibet Autonomous Region from 1 st ,July to 1 st ,September. Since particle size, shape and refractive index have an impact on linear particle depolarization ratio, one can classify the aerosol types and cloud phase in turn in the Tibetan Plateau and Qingdao area using linear particle depolarization ratio data. Generally, two calibration methods were applied: comparison of the lidar measurement data and CALIPSO simultaneous data method and half-wave plate ±45°switch method. In this paper we applied the comparison calibration method. The correlation coefficient between lidar measurement data and CALIPSO data reaches up to 84.92%, which shows great linear relation. Finally, after the calculation and calibration of the linear particle depolarization ratio measured during the plateau experiment campaign and observation in coastal area, the ice-water mixed cloud (0.15< p δ <0.5), water cloud ( p δ <0.15) and dusty mix(0.2< p δ <0.35) in Tibetan Plateau were occurred and classified. Meanwhile, the cirrus clouds ( p δ <0.5), water cloud, smoke and urban pollution (0.05< p δ <0.2) and dusty mix in Qingdao area were also occurred and classified.

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Saharan Mineral Dust Experiments SAMUM–1 and SAMUM–2: what have we learned?

Cited by 89 publications

References 110 publications

CALIPSO observations of transatlantic dust: vertical stratification and effect of clouds

CALIPSO observations of transatlantic dust: vertical stratification and effect of clouds

Identification and monitoring of Saharan dust: An inventory representative for south Germany since 1997

Research in depolarization of particles in Tibetan Plateau and coastal area by lidar

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