Understanding the long‐term variability of African dust transport across the Atlantic as recorded in both Barbados surface concentrations and large‐scale Total Ozone Mapping Spectrometer (TOMS) optical thickness

Abstract

[1] The interannual variability of African dust transport over the north tropical Atlantic is monitored using in situ surface concentrations measurements performed at Barbados since 1966, along with the Total Ozone Mapping Spectrometer (TOMS) and Meteosat dust optical thickness (DOT) records covering the last two decades. Despite their differences in spatial coverage, the two dust records are in good agreement at both monthly and annual timescales over the 22 years of common operation. This demonstrates that the Barbados dust record is representative of the year-to-year variability of dust export over the north tropical Atlantic during both winter and summer. The satellite DOT are used to assess the characteristics of the impact of climate factors, i.e., North Atlantic Oscillation (NAO) and Sahel drought, on dust emission and export as a function of season, and in terms of spatial extend of their influence. The analysis shows a large regional impact of Sahel drought on dust emissions and transport both in winter and in summer, whereas the influence of the NAO dominates the winter export and is more geographically limited to the eastern Atlantic north of 15°N, and possibly some localized source regions (southern Mauritania and the Bodele depression). Overall, the combination of the 35 years of Barbados measurements of African dust with 22 years of satellite dust survey over the Atlantic highlights very high dust loads in the mid-1980s related to the severe Sahel drought (maximum impact in 1983) and persistently high dusty conditions in the 1990s, most probably due to the continuation of relatively dry conditions in Sahel in the recent years.Citation: Chiapello, I., C. Moulin, and J. M. Prospero (2005), Understanding the long-term variability of African dust transport across the Atlantic as recorded in both Barbados surface concentrations and large-scale Total Ozone Mapping Spectrometer (TOMS) optical thickness,

Deep ocean mass fluxes in the coastal upwelling off Mauritania from 1988 to 2012: variability on seasonal to decadal timescales

“…The contribution of dust to the settling particles in the deep ocean off Cape Blanc amounts to one-third on average of the total mass flux , but it may be as high as 50 % during particular flux events (Nowald et al, 2015). As shown by Jickells et al (2005), modelled dust fluxes from the Saharan region and their variability may be influenced by ENSO and NAO cycles (see also Goudie and Middleton, 2001;Chiapello et al, 2005;Hsu et al, 2012;Diatta and Fink, 2014). During the time period of this study (1988( -2012, the wintertime (December-JanuaryFebruary-March = DJFM) NAO index after Hurrell (Hurrell, 1995) is characterized by switches from extremely positive (e.g.…”

Satellite perspective of aerosol intercontinental transport: From qualitative tracking to quantitative characterization

“…Moulin et al (1997) used daily Meteosat observations of dust from 1984-1994 and found that inter-annual variability of dust export to the North Atlantic Ocean and the Mediterranean Sea are well correlated with the North Atlantic Oscillation (NAO). By using multi-decadal TOMS AAI and ground-based dust measurements, Chiapello et al (2005) found that the Sahel drought has a large-scale impact on dust emissions and trans-Atlantic transport in both the subsequent winter and summer, and that the NAO controls the northern branch of wintertime transport. Doherty et al (2008), also using the multi-decadal TOMS AAI data, found that African dust is transported into the Caribbean via two routes associated with distinct source regions and controlled by different meteorology.…”

Black Carbon and West African Monsoon precipitation: observations and simulations

“…We then identified El Niño-Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), and Atlantic zonal and meridional sea surface temperature (SST) modes as known climate factors that modulate natural variability of aerosol and other meteorological variables (e.g. Prospero and Lamb, 2003;Chiapello et al, 2005;Washington et al, 2006).…”