Saharan dust infrared optical depth and altitude retrieved from AIRS: a focus over North Atlantic – comparison to MODIS and CALIPSO

Peyridieu, S.; Chédin, A.; Tanré, D.; Capelle, V.; Pierangelo, Clémence; Lamquin, Nicolas; Armante, R.

doi:10.5194/acp-10-1953-2010

Cited by 94 publications

(95 citation statements)

References 41 publications

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“…Comparison of MODIS AOD retrievals with collocated AERONET measurements confirms that 1 standard deviation of MODIS AOD falls within the initial predicted uncertainty of τ = ±0.03 ± 0.05τ over ocean and τ = ±0.05 ± 0.15τ over land, more than 60 % of the time over ocean and more than 72 % of the time over land (Remer et al, , 2008. It should be noted that MODIS observations have been used extensively to study dust aerosols above the Atlantic Ocean (e.g., Kaufman et al, 2005;Wong and Dessler, 2005;Kalashnikova and Kahn, 2008;Peyridieu et al, 2010;Ben-Ami et al, 2012;Peyridieu et al, 2013) due to their almost global coverage of the Earth on a daily basis, their availability from both TERRA and AQUA satellites and their good quality. MODIS AOD is used here as an additional constraint to DOF from CALIPSO regarding the spatial distribution of the SAL.…”

Section: Additional Data Setssupporting

confidence: 70%

“…Also, they can be used as a priori information (vertical distribution of dust aerosols) in satellite algorithms, which analyze data from instruments either in the UV spectrum (like TOMS or OMI) or in the IR spectrum (like AIRS or IASI) in order to improve the quality of their geophysical retrievals, as these instruments are sensitive to the vertical distribution. Further, as there are growing efforts to obtain the height of aerosols plumes from passive satellite instruments (Kahn et al, 2007;Joseph et al, 2008;Kokhanovsky and Rozanov, 2010;Peyridieu et al, 2010Peyridieu et al, , 2013, these results comprise a validation data set.…”

Section: Tsamalis Et Al: Sal Vertical Distribution 5 Summary and mentioning

confidence: 99%

“…In addition, the satellite observations of dust are sensitive to the vertical distribution, especially in the ultraviolet and infrared spectra, which makes the retrieval of dust characteristics from space more challenging (Quijano et al, 2000;Ginoux and Torres, 2003;Pierangelo et al, 2004;Torres et al, 2007). At the same time, this sensitivity permits for new generation infrared sounders to bring reliable information on the dust layer mean altitude (Peyridieu et al, 2010(Peyridieu et al, , 2013, but their new established results still need further validation. An accurate determination of the aerosol vertical distribution at the global scale can be achieved with the two-wavelength polarization-sensitive lidar CALIOP, launched onboard CALIPSO in April 2006 (Winker et al, 2007).…”

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The seasonal vertical distribution of the Saharan Air Layer and its modulation by the wind

Chédin²,

et al. 2013

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Abstract. The Saharan Air Layer (SAL) influences largescale environment from western Africa to eastern tropical Americas, by carrying large amounts of dust aerosols. However, the vertical distribution of the SAL is not well established due to a lack of systematic measurements away from the continents. This can be overcome by using the observations of the spaceborne lidar CALIOP onboard the satellite CALIPSO. By taking advantage of CALIOP's capability to distinguish dust aerosols from other types of aerosols through depolarization, the seasonal vertical distribution of the SAL is analyzed at 1 • horizontal resolution over a period of 5 yr (June 2006-May 2011. This study shows that SAL can be identified all year round displaying a clear seasonal cycle. It occurs higher in altitude and more northern in latitude during summer than during winter, but with similar latitudinal extent near Africa for the four seasons. The south border of the SAL is determined by the Intertropical Convergence Zone (ITCZ), which either prohibits dust layers from penetrating it or reduces significantly the number of dust layers seen within or south of it, as over the eastern tropical Atlantic. Spatially, near Africa, it is found between 5 • S and 15 • N in winter and 5-30 • N in summer. Towards the Americas (50 • W), SAL is observed between 5 • S and 10 • N in winter and 10-25 • N in summer. During spring and fall, SAL is found between the position of winter and summer not only spatially but also vertically. In winter, SAL occurs in the altitude range 0-3 km off western Africa, decreasing to 0-2 km close to South America. During summer, SAL is found to be thicker and higher near Africa at 1-5 km, reducing to 0-2 km in the Gulf of Mexico, farther west than during the other seasons. SAL is confined to one layer, of which the mean altitude decreases with westward transport by 13 m deg −1 during winter and 28 m deg −1 , after 30 • W, during summer. Its mean geometrical thickness decreases by 25 m deg −1 in winter and 9 m deg −1 in summer. Spring and fall present similar characteristics for both mean altitude and geometrical thickness. Wind plays a major role not only for the transport of dust within the SAL but also by sculpting it. During winter, the trade winds transport SAL towards South America, while in spring and summer they bring dust-free maritime air masses mainly from the North Atlantic up to about 50 • W below the SAL. The North Atlantic westerlies, with their southern border occurring between 15 and 30 • N (depending on the season, the longitude and the altitude), prevent the SAL from developing further northward. In addition, their southward shift with altitude gives SAL its characteristic oval shape in the northern part. The effective dry deposition velocity of dust particles is estimated to be 0.07 cm s −1 in winter, 0.14 cm s −1 in spring, 0.2 cm s −1 in summer and 0.11 cm s −1 in fall. Finally, the African Easterly Jet (AEJ) is observed to collocate with the maximum dust load of the SAL, and this might promote the differential...

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Section: Additional Data Setssupporting

confidence: 70%

Section: Tsamalis Et Al: Sal Vertical Distribution 5 Summary and mentioning

confidence: 99%

mentioning

confidence: 99%

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The seasonal vertical distribution of the Saharan Air Layer and its modulation by the wind

Chédin²,

et al. 2013

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“…Kaufman et al (2005) uses aerosol data retrieved from MODIS for dust transport and deposition over the Atlantic Ocean. Peyridieu et al (2010) uses the data from Atmospheric Infrared Sounder (AIRS) on board the NASA Aqua platform for Saharan dust over the North Atlantic. In addition, satellite retrievals of total aerosol are used to quantify the dust aerosol in and near source regions over the globe.…”

Section: Parameterization Of Aerosol Radiative Propertiesmentioning

confidence: 99%

Simulation of mineral dust aerosol with Piecewise Log-normal Approximation (PLA) in CanAM4-PAM

Peng

Salzen

2012

Atmos. Chem. Phys.

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Abstract.A new size-resolved dust scheme based on the numerical method of piecewise log-normal approximation (PLA) was developed and implemented in the fourth generation of the Canadian Atmospheric Global Climate Model with the PLA Aerosol Model (CanAM4-PAM). The total simulated annual global dust emission is 2500 Tg yr −1 , and the dust mass load is 19.3 Tg for year 2000. Both are consistent with estimates from other models. Results from simulations are compared with multiple surface measurements near and away from dust source regions, validating the generation, transport and deposition of dust in the model. Most discrepancies between model results and surface measurements are due to unresolved aerosol processes. Biases in long-range transport are also contributing. Radiative properties of dust aerosol are derived from approximated parameters in two size modes using Mie theory. The simulated aerosol optical depth (AOD) is compared with satellite and surface remote sensing measurements and shows general agreement in terms of the dust distribution around sources. The model yields a dust AOD of 0.042 and dust aerosol direct radiative forcing (ADRF) of −1.24 W m −2 respectively, which show good consistency with model estimates from other studies.

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“…The LMD method for the retrieval of dust characteristics from IASI observations was originally developed for application to the Atmospheric Infrared Sounder (AIRS) (Pierangelo et al, 2004(Pierangelo et al, , 2005, and then slightly modified as described in detail in Peyridieu et al (2010Peyridieu et al ( , 2013 and in Capelle et al (2014) for application to IASI. The method used to derive dust characteristics from IASI observations is a three-step physical algorithm based on a "Look-up Table" (LUT) approach.…”

Section: Iasi Lmd Algorithmmentioning

confidence: 99%

Comparison of dust layer heights from active and passive satellite sensors

Kylling¹,

Vandenbussche²,

Capelle³

et al. 2017

Preprint

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Abstract. Aerosol layer height is an essential parameter to understand the impact of aerosols on the climate system. As part of the European Space Agency Aerosol_cci project, aerosol layer height as derived from passive thermal and solar satellite sensors measurements, have been compared with aerosol layer heights estimated from CALIOP measurements. The Aerosol_cci project targeted dust type aerosol for this study. This ensures relatively unambiguous aerosol identification by the CALIOP processing chain. Dust layer height was estimated from thermal IASI measurements by four different algorithms (BIRA-IASB, 5 DLR, LMD, LISA) and from solar GOME-2 (KNMI) and SCIAMACHY (IUP) measurements. Due to differences in overpass time of the various satellites, a trajectory model was used to move the CALIOP derived dust heights in space and time to the IASI, GOME-2 and SCIAMACHY dust height pixels. It is not possible to construct a unique dust layer height from the CALIOP data. Thus two CALIOP derived layer heights were used: the cumulative extinction height defined to be the height where the CALIOP extinction column is half of the total extinction column; and the geometric mean height which is defined 10 as the geometrical mean of the top and bottom heights of the dust layer. In statistical average over all IASI data there is a general tendency to a positive bias of 0.5-0.8 km against CALIOP extinction-weighted height for three of the four algorithms assessed, while the fourth algorithm has almost no bias. When comparing to geometric mean height there is a shift by -0.5 km for all algorithms (getting close to zero for the three algorithms and turning negative for the fourth). The standard deviation of all algorithms is quite similar and ranges between 1.0 and 1.4 km. When looking at different conditions (day, night, land, 15 ocean) there is more detail in variabilities (e.g. all algorithms overestimate more at night than at day).

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Saharan dust infrared optical depth and altitude retrieved from AIRS: a focus over North Atlantic – comparison to MODIS and CALIPSO

Cited by 94 publications

References 41 publications

The seasonal vertical distribution of the Saharan Air Layer and its modulation by the wind

The seasonal vertical distribution of the Saharan Air Layer and its modulation by the wind

Simulation of mineral dust aerosol with Piecewise Log-normal Approximation (PLA) in CanAM4-PAM

Comparison of dust layer heights from active and passive satellite sensors

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