Radiative properties and direct radiative effect of Saharan dust measured by the C‐130 aircraft during SHADE: 1. Solar spectrum

Haywood, Jim M.; Francis, Peter N.; Osborne, S.; Glew, Martin D.; Loeb, Norman G.; Highwood, Eleanor J.; Tanré, D.; Myhre, Gunnar; Formenti, Paola; Hirst, Edwin

doi:10.1029/2002jd002687

Cited by 372 publications

(435 citation statements)

References 35 publications

(100 reference statements)

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“…On four other flights during DABEX, FAAM AODs were also within 10% of AOD estimates from Banizoumbou (Johnson et al, 2008b). The comparison here gives us confidence that the aircraft scattering and absorption measurements are of reasonable magnitude, and are not grossly affected by problems with sampling efficiency (as had been a concern when sampling dust aerosol during previous measurement campaigns with the Met Office C-130 aircraft (Haywood et al, 2003b)). …”

Section: Aerosol Optical Depthssupporting

confidence: 50%

Measurements of aerosol properties from aircraft, satellite and ground‐based remote sensing: a case‐study from the Dust and Biomass‐burning Experiment (DABEX)

Johnson

Christopher

Haywood

et al. 2009

Quart J Royal Meteoro Soc

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This paper presents aircraft measurements of aerosol optical properties and radiative effects from the Dust and Biomass-burning Experiment (DABEX) over West Africa. On 19 January 2006 cloud-free skies and high aerosol loading provided ideal conditions for an intercomparison of aircraft, satellite and ground-based remote sensing instruments. Aerosol size distributions, optical properties, aerosol optical depth (AOD) and downwelling solar radiation were measured by the UK FAAM aircraft in the region of Niamey, Niger. The aircraft in situ measurements showed a mixture of dust and biomass-burning aerosols and indicated an AOD of 0.79 (at 550 nm) that compared well against AODs from the Banizoumbou Aerosol Robotic Network (AERONET) site (0.74) and a Microtops sunphotometer (0.72). AERONET size distributions showed a good degree of similarity with the aircraft in situ measurements. AERONET single-scattering albedos were also in fairly close agreement with the aircraft, having values of 0.85 and 0.87, respectively (at 550 nm). Measurements of downwelling solar radiation from the aircraft compared well with measurements from the Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) at Niamey. Radiative transfer modelling suggested a 130-160 W m −2 instantaneous reduction of downwelling solar radiation by the aerosol column (15-18% of the total flux). Measurements of downwelling solar radiation compared reasonably well against radiative transfer modelling based on the aircraft in situ data. Satellite retrievals of AOD from MISR and MODIS Deep Blue were within 0.05 of the ground-based sunphotometers measurements although there were discrepancies in optical properties retrieved by MISR, as compared to AERONET and the aircraft.

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Section: Aerosol Optical Depthssupporting

confidence: 50%

Measurements of aerosol properties from aircraft, satellite and ground‐based remote sensing: a case‐study from the Dust and Biomass‐burning Experiment (DABEX)

Johnson

Christopher

Haywood

et al. 2009

Quart J Royal Meteoro Soc

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“…The latest version of these softwares can retrieve the complex refractive index as well as the optical thickness and particle size distribution (Nakajima et al 2003, Dubovik andKing 2000). The comparison of retrieved size spectrum between the Skyrad package and the method by Dubovik and King (2000) was shown by Haywood et al (2003). The differences were are not significant.…”

Section: Discussionmentioning

confidence: 99%

Characteristics of Aeolian Dust Observed by Sky-Radiometer in the Intensive Observation Period 1 (IOP1)

Uchiyama

Yamazaki

Togawa

et al. 2005

Journal of the Meteorological Society of Japan

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A sky-radiometer network was developed in order to investigate the characteristics of aeolian dust on the way of transportation from the source region to the Japan area. From the analysis of the skyradiometer data, optical thickness in the visible to near infrared regions and size spectrum from radius 0.01 to 5 mm can be obtained. Five observation sites are set at Aksu, Qira, Shapotou, Qingdao, and Beijing in China, and four observation sites at Naha, Fukuoka, Nagoya and Tsukuba in Japan. The data of six observation sites (Qira, Shapotou, Naha, Fukuoka, Nagoya and Tsukuba) are automatically transferred to Meteorological Research Institute (MRI) through telephone lines.The following results were obtained from the data analysis of intensive observation period (IOP) in April, 2002. (1) The data with Å ngström exponent between 0.0 and 0.5 corresponds to the dust event day data. (2) The contribution of the particles with radius greater than 0.5 mm, which correspond to coarse dust particles, to the total optical thickness frequently exceeds more than @70% in the source region, and exceeds in Qingdao and sites in Japan on the dust event day. (3) The contribution of particles with radius greater than 0.5 mm to the total volume is more than @80% on the dust event day. (4) The retrieved volume spectrum in the source region, Aksu and Qira, is not dependent on the optical thickness. This means that the floating aerosols mainly consist of dust particles in the source region. (5) The total volume observed in Japan sites is one third of that in the source region. (6) When the size distribution for the coarse mode (r > 0:5 mm) is approximated by log-normal size distribution, effective radius r eff is 2.1 to 2.3 mm in China sites and 1.6 to 1.8 mm in Japan sites. r g is about 0.7 mm at Aksu, Qira, and Shapotou and about 0.5 mm at other sites (ln r g is the center of log-normal size distribution). The width of size distribution ðs g Þ is scattered between 0.67 and 0.87. These difference of size distribution among the observation sites are caused by the modification of air mass including aeolian dust; coarser dust particles are partially removed during the transportation, and the air mass including aeolian dust as a main component are partially contaminated by the aerosol into the atmosphere from anthropogenic activities. The observation network of ADEC caught this change clearly.

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“…On a regional scale, the radiative impact of dust can be much stronger. For instance, above the West African coast, Haywood et al (2003) measured a reduction of direct radiation at TOA of −130 W m −2 in the solar spectrum during an intense episode of dust transport (aerosol optical depth ∼1.5 at mid-visible wavelengths).…”

Section: Introductionmentioning

confidence: 99%

Physico‐chemical and optical properties of Sahelian and Saharan mineral dust: in situ measurements during the GERBILS campaign

Klaver

Formenti

Caquineau

et al. 2011

Quart J Royal Meteoro Soc

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Regardless of origin, clays (illite, kaolinite) dominated the total volume (79-90%); the remainder was composed of quartz, calcium-rich minerals (calcite, dolomite, gypsum) and alkali feldspars. Iron oxides, measured using a selective chemical extraction method, accounted for 1-3% of the total dust mass. The dependence of particle number size and shape distribution on the origin of dust seems minor too, although our results might be slightly misleading due to the fact that those kinds of data have been gathered on flights when dust had comparable origins and residence time.Mineral dust is only weakly absorbing in the mid-visible wavelengths (single scattering albedo ω 0 > 0.95 at 550 nm), and ω 0 measured values can be reproduced by measuring the bulk fractions of the major minerals, i.e. clays, quartz, calcite and iron oxides. At this wavelength, knowledge of the nature of clays and iron oxides, or the state of mixing of the minerals, does not induce significant differences in the results. A more precise description of the nature of clays and iron oxides is necessary at lower wavelengths owing to larger differences in their spectral optical properties. In particular, knowledge of the nature of the dominant clay is important for determining light scattering in the backward hemisphere.

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Radiative properties and direct radiative effect of Saharan dust measured by the C‐130 aircraft during SHADE: 1. Solar spectrum

Cited by 372 publications

References 35 publications

Measurements of aerosol properties from aircraft, satellite and ground‐based remote sensing: a case‐study from the Dust and Biomass‐burning Experiment (DABEX)

Measurements of aerosol properties from aircraft, satellite and ground‐based remote sensing: a case‐study from the Dust and Biomass‐burning Experiment (DABEX)

Characteristics of Aeolian Dust Observed by Sky-Radiometer in the Intensive Observation Period 1 (IOP1)

Physico‐chemical and optical properties of Sahelian and Saharan mineral dust: in situ measurements during the GERBILS campaign

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