Lidar ratio of Saharan dust over Cape Verde Islands: Assessment and error calculation

Groß, Silke; Wiegner, Matthias; Freudenthaler, Volker; Toledano, Carlos

doi:10.1029/2010jd015435

Cited by 28 publications

(38 citation statements)

References 48 publications

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“…As a result of this study, we are able to extend our series of dust measurements from the source region (Ouarzazate, Morocco, SAMUM‐1) [ Freudenthaler et al , 2009] and under conditions of mid‐range transport (Cape Verde, SAMUM‐2) [ Groß et al , 2011a] to long‐range transport conditions (Munich). Thus, possible changes of the properties of dust as it ages can be studied.…”

Section: Comparison With Samum Resultsmentioning

confidence: 98%

“…To improve the knowledge on microphysical and optical properties of mineral dust, dedicated observations were made during several field campaigns, e.g., SHADE and ACE‐Asia at the beginning of this century. Recently, two experiments took place in the framework of the “Saharan mineral dust experiment”, SAMUM: the focus of the first campaign in Morocco in May and June 2006 was on pure, fresh Saharan dust [ Heintzenberg , 2009], the second campaign was conducted at the Cape Verde Islands in January and February 2008 and dealt with mid‐range transported dust and dust in different mixing states [ Groß et al , 2011a]. Both experiments provided excellent data sets for a full description of dust aerosols, however, characterization of dust transported in the long range regime are still rare.…”

Section: Introductionmentioning

confidence: 99%

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The May/June 2008 Saharan dust event over Munich: Intensive aerosol parameters from lidar measurements

Wiegner¹,

Groß²,

Freudenthaler³

et al. 2011

J. Geophys. Res.

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[1] At the end of May 2008 one of the strongest Saharan dust outbreaks ever reached Central Europe. This event gave us the opportunity to extend our series of studies on Saharan dust characterization, which includes measurements near the source (SAMUM-1, Morocco) and in the regime of mid range transport (SAMUM-2, Cape Verde). The optical properties of the aerosol particles as a function of time and height are derived from data of the two Raman depolarization-lidar systems MULIS and POLIS at Munich and Maisach (Germany), respectively. Measurements include the extensive properties of the particles, backscatter coefficient b p and extinction coefficient a p , and the intensive particle properties, linear depolarization ratio d p and lidar ratio S p . All quantities are derived at two wavelengths, l = 355 nm and l = 532 nm. The focus of the study is on the intensive properties, for which we found on average d p = 0.30 at 355 nm and d p = 0.34 at 532 nm. The systematic errors were typically larger than the d p -difference at the two wavelengths. With respect to the lidar ratio, we found S p = 59 sr for both wavelengths, with an uncertainty range between ±4 sr and ±10 sr. These values are quite similar to the results from the SAMUM campaigns. Thus, our results suggest that the intensive optical properties of Saharan dust do not change significantly if the transport time is less than one week. However, more case studies in the far-range regime are required to scrutinize this statement. To further refine conclusions with respect to the wavelength dependence of d p a further reduction of the errors is desired.

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Section: Comparison With Samum Resultsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

The May/June 2008 Saharan dust event over Munich: Intensive aerosol parameters from lidar measurements

Wiegner¹,

Groß²,

Freudenthaler³

et al. 2011

J. Geophys. Res.

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“…The relationship between the retrieval error (σ ε j, 3 (41) is obtained from (32) by treating the range-corrected random noises (dU k ) as independent Gaussian random variables with standard deviation σ U k . The retrieval error due to noise in the calibration cell is given by (43) and is similarly derived using the approximation shown, which is described in [41] (Sec. 3.2 and Table 1, p. 3386).…”

Section: First-order Backscatter-coefficient Error Boundsmentioning

confidence: 99%

“…These errors in the input parameters to the retrieval are more appropriately described by a worst case deviation from their nominal value, assuming that input errors may uniformly be distributed between these worst case limits. A similar approach for the Raman lidar inversion algorithm is described in [43].…”

mentioning

confidence: 99%

Backscatter Error Bounds for the Elastic Lidar Two-Component Inversion Algorithm

Rocadenbosch

Frasier

Kumar

et al. 2012

IEEE Trans. Geosci. Remote Sensing

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Total backscatter-coefficient inversion error bounds for the two-component lidar inversion algorithm (so-called Fernald's or Klett-Fernald-Sasano's method) are derived in analytical form in response to the following three error sources: 1) the measurement noise; 2) the user uncertainty in the backscatter-coefficient calibration; and 3) the aerosol extinctionto-backscatter ratio. The following two different types of error bounds are presented: 1) approximate error bounds using first-order error propagation and 2) exact error bounds using a total-increment method. Both error bounds are formulated in explicit analytical form, which is of advantage for practical physical sensitivity analysis and computational implementation. A Monte Carlo approach is used to validate the error bounds at 355-, 532-, and 1064-nm wavelengths.

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“…A typical vertical smoothing of ≈ 940 m (250 rangebins) is applied to further increase the signal-to-noise ratio. The errors of the retrieved optical properties are calculated according to Groß et al (2011c).…”

Section: Discussionmentioning

confidence: 99%

Optical properties of long-range transported Saharan dust over Barbados as measured by dual-wavelength depolarization Raman lidar measurements

et al. 2015

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Abstract. Dual-wavelength Raman and depolarization lidar observations were performed during the Saharan Aerosol Long-range Transport and Aerosol-Cloud interaction Experiment in Barbados in June and July 2013 to characterize the optical properties and vertical distribution of long-range transported Saharan dust after transport across the Atlantic Ocean. Four major dust events were studied during the measurements from 15 June to 13 July 2013 with aerosol optical depths at 532 nm of up to 0.6. The vertical aerosol distribution was characterized by a three-layer structure consisting of the boundary layer, the entrainment or mixing layer and the pure Saharan dust layer. The upper boundary of the pure dust layer reached up to 4.5 km in height. The contribution of the pure dust layer was about half of the total aerosol optical depth at 532 nm. The total dust contribution was about 50-70 % of the total aerosol optical depth at 532 nm. The lidar ratio within the pure dust layer was found to be wavelength independent with mean values of 53 ± 5 sr at 355 nm and 56 ± 7 sr at 532 nm. For the particle linear depolarization ratio, wavelength-independent mean values of 0.26 ± 0.03 at 355 nm and 0.27 ± 0.01 at 532 nm have been found.

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Lidar ratio of Saharan dust over Cape Verde Islands: Assessment and error calculation

Cited by 28 publications

References 48 publications

The May/June 2008 Saharan dust event over Munich: Intensive aerosol parameters from lidar measurements

The May/June 2008 Saharan dust event over Munich: Intensive aerosol parameters from lidar measurements

Backscatter Error Bounds for the Elastic Lidar Two-Component Inversion Algorithm

Optical properties of long-range transported Saharan dust over Barbados as measured by dual-wavelength depolarization Raman lidar measurements

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