The Three-Dimensional Structure of Transatlantic African Dust Transport: A New Perspective from CALIPSO LIDAR Measurements

Abstract

The lack of information on the vertical distribution of dust, in turn, results in large uncertainties when attempting to evaluate the impacts of dust on climate processes. We analyzed over two years of LIDAR measurements from NASA’s CALIPSO and CloudSat satellites to document the vertical pathways of transatlantic transport of Saharan dust. Our analysis overcomes the limitations of quantitative dust detections with passive satellite measurements over land and low clouds and provides the fine vertical resolved structures. The results show the strong seasonal shift in dust source regions and transportation pathways due to the meteorological and thermodynamical conditions, which also control the dust vertical distribution as well as the depth of the dust layer. The dust layer top descending rates of 35 m/degree in summer, 25 m/degree in autumn and spring, and 10 m/degree in winter are found, respectively, while the dust is being transported across the Atlantic. Comparison with the model simulation highlights the potentials of dust observations using CALIPSO LIDAR. The observed seasonal dependence of these pathways gives new insights into the transport of the Saharan dust and provides important guidance for simulations of the production and transport of the global dust aerosol.

The transatlantic dust transport from North Africa to the Americas—Its characteristics and source regions

“…Well‐known features of the transatlantic transport are reproduced by the model. The seasonality of horizontal and vertical structures is consistent with satellite data presented by Liu et al [] and Alizadeh‐Choobari et al []. The combination of Eulerian and Lagrangian diagnostics allows for a specification of the transport duration from the dust emission until rainout in the target areas.…”

Seasonal cycle of desert aerosols in western Africa: analysis of the coastal transition with passive and active sensors

“…5d). According to Adams et al (2012), the heart of the SAL is located about 5 km above sea level in SON, whereas Liu et al (2012) show a maximum altitude of 4 km.…”

“…Some studies relating aerosols to their transport are generally a simple description of the vertical distribution of aerosols in the SAL (Generoso et al, 2008;Liu et al, 2008;Ben-Ami et al, 2009;Braun, 2010;Yu et al, 2010;Adams et al, 2012;Ridley et al, 2012;Yang et al, 2012) or a description of the seasonality of the SAL in connection with large-scale dynamics (Liu et al, 2012;Tsamalis et al, 2013). However, the dust field campaigns, AMMA, SAMMUM-1 and SAMMUM-2, FENNEC, and SALTRACE (see Table 1) of Weinzierl et al (2016) carried out in western Africa and over the Atlantic Ocean improved our understanding of dust-dynamics interactions.…”

Meteorological, atmospheric and climatic perturbations during major dust storms over Indo-Gangetic Basin

“…Lidar systems onboard satellites have been increasingly used in the recent years for monitoring the dust storms, their transport and vertical extent (Liu et al, 2012), since the dust-aerosol vertical profiles play a crucial role in radiative forcing and atmospheric heating rate (Lemaitre et al, 2010). The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite was launched on April 28, 2006 to study the vertical distributions, optical and physical properties of aerosols and clouds at 532 and 1064 nm as well as their impact on the Earth's radiation budget and climate.…”

“…The main source of suspended dust is the arid and desert areas over the globe (Prospero et al, 2002;Ginoux et al, 2012;Crosbie et al, 2014), while depending on the wind field dust is transported from one continent to another (Liu et al, 2012;Nastos, 2012). Middle East, Arabia, southwest Asia, and Thar desert are the main sources for dust which are transported over the IGB depending upon the intensity of westerly winds and meteorological conditions Sharma et al, 2012;Gharai et al, 2013;Aher et al, 2014;Kaskaoutis et al, in press-a), western Himalayan range (Hegde et al, 2007;Guleria et al, 2011;Srivastava et al, 2011a;Kumar et al, 2014) and beyond to the far east up to the Everest region and Darjeeling (Duchi et al, 2011;Chatterjee et al, 2012), hundreds to thousands of kilometers away from the dust source.…”