Interannual variability in Saharan dust over the North Atlantic Ocean and its relation to meteorological fields during northern winter

Nakamae, K.; Shiotani, Masato

doi:10.1016/j.atmosres.2012.09.012

Cited by 17 publications

(10 citation statements)

References 55 publications

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“…Explaining such interannual variability has been the focus of prior work, with many studies focusing on the quantity of mineral dust traversing the Atlantic Ocean and reaching the Americas. For the winter season, observations of mineral dust over the Atlantic Ocean and at Barbados have been related to variability in the North Atlantic Oscillation (NAO) (Moulin et al, 1997;Chiapello and Moulin, 2002;Evan et al, 2006b;Nakamae and Shiotani, 2013). Similar relationships between the NAO and mineral dust have been diagnosed from global chemistry and transport model results (Ginoux et al, 2004).…”

Section: Introductionmentioning

confidence: 64%

Role of the convergence zone over West Africa in controlling Saharan mineral dust load and transport in the boreal summer

Doherty

Riemer

Hameed

2014

Tellus B: Chemical and Physical Meteorology

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A B S T R A C T During summer, large amounts of mineral dust are emitted and transported from North Africa over the tropical North Atlantic towards the Caribbean with the exact quantity varying greatly from year to year. Much effort has been made to explain the variability of summer season mineral dust load, for example, by relating dust variability to teleconnection indices such as ENSO and the NAO. However, only weak relationships between such climate indices and the abundance of mineral dust have been found. In this work, we demonstrate the role of the near-surface convergence zone over West Africa in controlling dust load and transport of mineral dust. We apply the 'Center of Action' approach to obtain indices that quantify the movement and strength of the convergence zone using NCEP/NCAR Reanalysis data. The latitudinal position of the convergence zone is significantly correlated with the quantity of mineral dust at Barbados over the period 1965Á2003 (r0(0.47). A southward displacement of the convergence zone is associated with both increased near-surface flow and decreased precipitation over the dust source regions of the southern Saharan desert, Sahel and Lake Chad. This in turn reduces soil moisture and vegetation, furthering the potential for dust emission. In contrast, the intensity of the convergence zone is not correlated with dust concentration at Barbados. We conclude that the coupling of changes in near-surface winds with changes in precipitation in source regions driven by a southward movement of the convergence zone most directly influence dust load at Barbados and over the tropical North Atlantic during summer.

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Section: Introductionmentioning

confidence: 64%

Role of the convergence zone over West Africa in controlling Saharan mineral dust load and transport in the boreal summer

Doherty

Riemer

Hameed

2014

Tellus B: Chemical and Physical Meteorology

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“…These ratios are very useful to explain acidity of precipitation (Jain et al, 2000;Satyanarayana et al, 2010). The highest concentration of Na + among all cations and Cl -among all anions clearly indicated the influence of (Nakamae and Shiotani, 2013). High contribution of SO 4 2-in snow samples might be due to both marine as well as anthropogenic contributions.…”

Section: Clusterwise Chemical Composition Of Snowmeltmentioning

confidence: 99%

Long Range Transport and Wet Deposition Fluxes of Major Chemical Species in Snow at Gulmarg in North Western Himalayas (India)

Kumar

Singh

Gupta

et al. 2016

Aerosol Air Qual. Res.

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The study reports snow chemistry and long range transport of pollutants at Gulmarg in north-western Himalayan region of India during winters of 2012-2013. The pH of snowmelt varied between 5.16 and 7.68 with an average of 5.90. The frequency distribution of pH of snowmelt showed that the maximum number of samples (31%) had pH between 6.81 and 7.20. However, 12% samples were observed to be acidic (below 5.6 respectively. Both local emissions as well as long range transport (LRT) of pollutants were found to be the sources of these ionic species. Backward airmass trajectory calculations showed that this site received airmasses from six major sectors i.e., i) North Atlantic Ocean origin (NAO), ii) African origin (Af), iii) Middle East origin (ME), iv) European origin (Eu), v) Western India origin (InW), vi) Pakistan origin (Pk). The highest average pH (7.58) of the snowfall was noticed during InW airmasses which had the lowest ratios of nssSO 4 2-/nssCa 2+ and NO 3 -/nssCa 2+ . Very high pH has been observed in precipitation samples at Indian sites due to buffering of acidic components by atmospheric dust rich in CaCO 3 . The lowest pH (4.94) was noticed for ME airmasses which had the highest nssSO 4 2-/nssCa 2+ and NO 3 -/nssCa 2+ ratios. Data of present study was compared with a study reported almost three decades ago. We noticed a drastic increase in the concentrations of anthropogenic components such as nssSO 4 2-(114%), NO 3 -(109%) and NH 4 + (90%). This is probably due to increase in LRT of pollutants as well as local activities during past three decades.

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“…The maxima only show significant trends in June and principally in December (0.16˚C ± 0.12˚C/decade), while the minima rise every month, but especially in March (0.18˚C ± 0.11˚C/ decade) and October (0.15˚C ± 0.08˚C/decade). The increase in the máxima of December could be related to the intrusion of warm air from North Africa described by Nakamae & Shiotani (2013) [10] for the northern winter. The temperature range tended to decrease, although in many months the trend was not statistically significant.…”

Section: T Ave T Max T Min Dtr Whole Island Series E + F + G + H + Jmentioning

confidence: 99%

“…Warming was greater in the minima than the maxima, and on the summit above 2000 m a.s.l., it was greater than on the rest of the island, and also in the windward mid-altitude areas exposed to the prevailing winds, than similar leeward areas. The global circulation may exert greater influence on the warming in the high mountains [7] and the sea temperature on the coast air temperature [8], while in the windward mid-altitude areas the main factor is the local effect of the trade winds [1] and heated air invasions from Sahara during dust outbreak events [9,10]. Trends in sea surface temperature (SST) also show that warming of the sea surrounding the archipelago is higher as we move southward [4].…”

Section: Introductionmentioning

confidence: 99%

Temperature Trends on Gran Canaria (Canary Islands). An Example of Global Warming over the Subtropical Northeastern Atlantic

Luque¹,

Martin²,

Dorta³

et al. 2014

ACS

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The variation in temperature on the island of Gran Canaria is studied using the method applied to the nearby island of Tenerife [1]. An upward warming trend of 0.09˚C ± 0.05˚C (α = 0.01) was seen from 1946 to date, which has accelerated since the seventies to 0.17˚C ± 0.10˚C (α = 0.01). The increase was higher at night (0.11˚C ± 0.05˚C) than by day (0.08˚C ± 0.06˚C), so the temperature range decreased slightly. These values are similar to those of Tenerife and the time series of anomalies for the two islands are highly correlated. On the coast the same relationship to the sea surface temperature was found as in Tenerife, but in the mid-altitude areas to windward, some differences were detected that are hypothetically attributable to the different relief of the two islands.

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Interannual variability in Saharan dust over the North Atlantic Ocean and its relation to meteorological fields during northern winter

Cited by 17 publications

References 55 publications

Role of the convergence zone over West Africa in controlling Saharan mineral dust load and transport in the boreal summer

Role of the convergence zone over West Africa in controlling Saharan mineral dust load and transport in the boreal summer

Long Range Transport and Wet Deposition Fluxes of Major Chemical Species in Snow at Gulmarg in North Western Himalayas (India)

Temperature Trends on Gran Canaria (Canary Islands). An Example of Global Warming over the Subtropical Northeastern Atlantic

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