Metagenomic investigation of African dust events in the Caribbean

2020 ◽  
Vol 367 (7) ◽  
Author(s):  
Samantha Marie Waters ◽  
S K Purdue ◽  
R Armstrong ◽  
Y Detrés
Keyword(s):  
Environmental Samples ◽  
Saharan Dust ◽  
Boreal Summer ◽  
Southern United States ◽  
Prominent Feature ◽  
Microbial Transport ◽  
Microbial Composition ◽  
African Dust ◽  
The Caribbean ◽  
Dust Events

ABSTRACT African dust from the Sahara and Sahel regions of Northern Africa is blown intercontinental distances and is the highest portion of atmospheric dust generated each year. During the Northern Hemisphere summer months (boreal summer), these dust events travel into the Caribbean and southern United States. While viability assays, microscopy and bacterial amplicon analyses have shown that dust-associated microbes may be diverse, the specific microbial taxa that are transported intercontinental distances with these dust events remain poorly characterized. To provide new insights into these issues, five metagenomes of Saharan dust events occurring in the Caribbean, collected in the summer months of 2002 and 2008, were analyzed. The data revealed that similar microbial composition existed between three out of the five of the distinct dust events and that fungi were a prominent feature of the metagenomes compared to other environmental samples. These results have implications for better understanding of microbial transport through the atmosphere and may implicate that the dust-associated microbial load transiting the Atlantic with Saharan dust is similar from year to year.

Impacts of long-range-transported Saharan dust layers on atmospheric stability and turbulence in the trades

2021 ◽  
Author(s):  
Manuel Gutleben ◽  
Silke Groß ◽  
Martin Wirth
Keyword(s):  
Water Vapor ◽  
Radiative Transfer ◽  
Mineral Dust ◽  
Atmospheric Stability ◽  
Power Spectra ◽  
Saharan Dust ◽  
Dust Particles ◽  
Boreal Summer ◽  
The Caribbean ◽  
Wavelet Analyses

<p>Aeolian Saharan mineral dust particles can be transported over long distances. Great amounts of Saharan mineral dust particles are transported westwards over the Atlantic Ocean towards the Caribbean islands especially during the boreal summer months. During the transport they can either have a direct environmental effect by absorbing, emitting and scattering radiation or an indirect effect by changing cloud micro-physical properties and by modifying cloud lifetime or formation.</p><p>Our recent studies indicate that elevated transported Saharan dust layers, so-called Saharan Air Layers (SALs), come along with enhanced concentrations of water vapor compared to the surrounding atmosphere. Radiative transfer simulations reveal that not the dust particles inside the SALs but the enhanced concentrations of water vapor play the dominant role for atmospheric heating in dust-laden subtropical regions. In this way water vapor has the potential to impact both atmospheric stability and turbulent properties not only inside the SALs but also at lower atmospheric levels.  To study the effects of water vapor on atmospheric turbulence and stability in SAL-regions, we performed wavelet analyses as well as calculations of power spectra on the basis of airborne lidar backscatter and water vapor measurements by the DLR lidar system WALES during the NARVAL-II research campaign. For an in-depth investigation of SAL-properties, several research flights during NARVAL-II were designed to lead over dust-laden regions upstream the Caribbean island of Barbados. Our analysis shows that water vapor heating does not only have an effect on the stability and turbulence of SALs by maintaining their confining inversions and promoting vertical mixing in their interior, but also hinders the development of shallow marine convection below.</p><p>In our presentation we will give an overview of the performed measurements and radiative transfer simulations as well as of the conducted stability and turbulence analyses by means of calculated power spectra and wavelet analyses.</p>

scholarly journals Sun photometer retrievals of Saharan dust properties over Barbados during SALTRACE

2019 ◽  
Vol 19 (23) ◽  
pp. 14571-14583 ◽  
Author(s):  
Carlos Toledano ◽  
Benjamín Torres ◽  
Cristian Velasco-Merino ◽  
Dietrich Althausen ◽  
Silke Groß ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Saharan Dust ◽  
Caribbean Region ◽  
The Sun ◽  
Concentration Data ◽  
The Caribbean ◽  
Sun Photometer ◽  
Dust Events

Abstract. The Saharan Aerosol Long-Range Transport and Aerosol–Cloud-Interaction Experiment (SALTRACE) was devoted to the investigation of Saharan dust properties over the Caribbean. The campaign took place in June–July 2013. A wide set of ground-based and airborne aerosol instrumentation was deployed at the island of Barbados for a comprehensive experiment. Several sun photometers performed measurements during this campaign: two AERONET (Aerosol Robotic Network) Cimel sun photometers and the Sun and Sky Automatic Radiometer (SSARA). The sun photometers were co-located with the ground-based multi-wavelength lidars BERTHA (Backscatter Extinction lidar Ratio Temperature Humidity profiling Apparatus) and POLIS (Portable Lidar System). Aerosol properties derived from direct sun and sky radiance observations are analyzed, and a comparison with the co-located lidar and in situ data is provided. The time series of aerosol optical depth (AOD) allows identifying successive dust events with short periods in between in which the marine background conditions were observed. The moderate aerosol optical depth in the range of 0.3 to 0.6 was found during the dust periods. The sun photometer infrared channel at the 1640 nm wavelength was used in the retrieval to investigate possible improvements to aerosol size retrievals, and it was expected to have a larger sensitivity to coarse particles. The comparison between column (aerosol optical depth) and surface (dust concentration) data demonstrates the connection between the Saharan Air Layer and the boundary layer in the Caribbean region, as is shown by the synchronized detection of the successive dust events in both datasets. However the differences of size distributions derived from sun photometer data and in situ observations reveal the difficulties in carrying out a column closure study.

Assessment of a new detection threshold for PM10 concentrations linked to African dust events in the Caribbean Basin

2020 ◽  
Vol 224 ◽  
pp. 117354 ◽  
Author(s):  
Lovely Euphrasie-Clotilde ◽  
Thomas Plocoste ◽  
Tony Feuillard ◽  
Cristian Velasco-Merino ◽  
David Mateos ◽  
...  
Keyword(s):  
Detection Threshold ◽  
Caribbean Basin ◽  
African Dust ◽  
The Caribbean ◽  
Dust Events

scholarly journals Sun photometer retrievals of Saharan dust properties over Barbados during SALTRACE

2019 ◽  
Author(s):  
Carlos Toledano ◽  
Benjamín Torres ◽  
Cristian Velasco-Merino ◽  
Dietrich Althausen ◽  
Silke Groß ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Saharan Dust ◽  
Caribbean Region ◽  
The Sun ◽  
Concentration Data ◽  
The Caribbean ◽  
Sun Photometer ◽  
Dust Events

Abstract. The Saharan Aerosol Long-range Transport and Aerosol-Cloud-Interaction Experiment (SALTRACE) was devoted to the investigation of Saharan dust properties over the Caribbean. The campaign took place in June–July 2013. A wide set of ground-based and airborne aerosol instrumentation was deployed at Barbados island for a comprehensive experiment. Several sun photometers performed measurements during this campaign: two AERONET Cimel sun photometers and the Sun and Sky Automatic Radiometer (SSARA). The sun photometers were co-located with the ground-based multi-wavelength lidars BERTHA and POLIS. Aerosol properties derived from direct sun and sky radiance observations are analyzed, and a comparison with the co-located lidar and in-situ data is provided. The time series of aerosol optical depth allows identifying successive dust events with short periods in between in which the marine background conditions were observed. Moderate aerosol optical depth in the range 0.3 to 0.6 was found during the dust periods. The sun photometer infrared channel at 1640 nm wavelength was used in the retrieval to investigate possible improvements and expected larger sensitivity to coarse particles. The comparison between column (AOD) and surface (dust concentration) data demonstrates the connection between the Saharan Air Layer and the boundary layer in the Caribbean region, as it is shown by the synchronized detection of the successive dust events in both data sets. However the comparison of size distributions derived from sun photometer data and in-situ observations reveal the difficulties to carry out a column closure study.

scholarly journals Saharan dust and giant quartz particle transport towards Iceland

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
György Varga ◽  
Pavla Dagsson-Walhauserová ◽  
Fruzsina Gresina ◽  
Agusta Helgadottir
Keyword(s):  
Numerical Models ◽  
Saharan Dust ◽  
Atmospheric Environment ◽  
The Arctic ◽  
Dust Particles ◽  
Atmospheric Flow ◽  
Dust Transport ◽  
Strong Winds ◽  
Dust Events ◽  
Local Dust

AbstractMineral dust emissions from Saharan sources have an impact on the atmospheric environment and sedimentary units in distant regions. Here, we present the first systematic observations of long-range Saharan dust transport towards Iceland. Fifteen Saharan dust episodes were identified to have occurred between 2008 and 2020 based on aerosol optical depth data, backward trajectories and numerical models. Icelandic samples from the local dust sources were compared with deposited dust from two severe Saharan dust events in terms of their granulometric and mineralogical characteristics. The episodes were associated with enhanced meridional atmospheric flow patterns driven by unusual meandering jets. Strong winds were able to carry large Saharan quartz particles (> 100 µm) towards Iceland. Our results confirm the atmospheric pathways of Saharan dust towards the Arctic, and identify new northward meridional long-ranged transport of giant dust particles from the Sahara, including the first evidence of their deposition in Iceland as previously predicted by models.

Relationship between African dust carried in the Atlantic trade winds and surges in pediatric asthma attendances in the Caribbean

2008 ◽  
Vol 52 (8) ◽  
pp. 823-832 ◽  
Author(s):  
Joseph M. Prospero ◽  
Edmund Blades ◽  
Raana Naidu ◽  
George Mathison ◽  
Haresh Thani ◽  
...  
Keyword(s):  
Pediatric Asthma ◽  
Trade Winds ◽  
African Dust ◽  
Atlantic Trade ◽  
The Caribbean

scholarly journals New developments in the representation of Saharan dust sources in the aerosol–climate model ECHAM6-HAM2

2016 ◽  
Vol 9 (2) ◽  
pp. 765-777 ◽  
Author(s):  
Bernd Heinold ◽  
Ina Tegen ◽  
Kerstin Schepanski ◽  
Jamie R. Banks
Keyword(s):  
Climate Model ◽  
Dust Emission ◽  
Source Area ◽  
Saharan Dust ◽  
Moist Convection ◽  
Dust Source ◽  
New Developments ◽  
Infrared Imager ◽  
Dust Sources ◽  
Dust Events

Abstract. In the aerosol–climate model ECHAM6-HAM2, dust source activation (DSA) observations from Meteosat Second Generation (MSG) satellite are proposed to replace the original source area parameterization over the Sahara Desert. The new setup is tested in nudged simulations for the period 2007 to 2008. The evaluation is based on comparisons to dust emission events inferred from MSG dust index imagery, Aerosol Robotic Network (AERONET) sun photometer observations, and satellite retrievals of aerosol optical thickness (AOT).The model results agree well with AERONET measurements especially in terms of seasonal variability, and a good spatial correlation was found between model results and MSG-SEVIRI (Spinning-Enhanced Visible and InfraRed Imager) dust AOT as well as Multi-angle Imaging SpectroRadiometer (MISR) AOT. ECHAM6-HAM2 computes a more realistic geographical distribution and up to 20 % higher annual Saharan dust emissions, using the MSG-based source map. The representation of dust AOT is partly improved in the southern Sahara and Sahel. In addition, the spatial variability is increased towards a better agreement with observations depending on the season. Thus, using the MSG DSA map can help to circumvent the issue of uncertain soil input parameters.An important issue remains the need to improve the model representation of moist convection and stable nighttime conditions. Compared to sub-daily DSA information from MSG-SEVIRI and results from a regional model, ECHAM6-HAM2 notably underestimates the important fraction of morning dust events by the breakdown of the nocturnal low-level jet, while a major contribution is from afternoon-to-evening emissions.

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