Spatio-temporal distribution and transport of particulate matter in the eastern tropical North Atlantic observed by Argo floats

A list of North Atlantic polar lows was compiled for 2015–2017. A total of 131 polar lows were found by analyzing the Moderate Resolution Imaging Spectroradiometer (MODIS) infrared imagery and auxiliary information. The study region was additionally divided by the 20° W meridian to assess possible differences in the polar lows occurring in the western and eastern parts of the region. The highest polar low activity was found over the Barents Sea and the northern Norwegian Sea. A large number of polar lows over this region were dual or multiple. When considering such systems as a single event, more polar lows were found in 2015 over the Labrador Sea and southern Davis Strait, which is the region with the second highest number of polar lows. High interannual variability of polar low frequency was noted, which was more pronounced in the western part of the region. During the analyzed period, the largest number of polar lows occurred in January for the western part of the region and in February for the eastern part. The main polar low parameters were similar within the region, with the mean values slightly higher in the western part of the region, but all extreme high values were observed in the eastern part.

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Spatio-Temporal Distribution and Health Risk Levels of TSP and PM10 in the Mining Town of Tarkwa, Ghana

Ghana Mining Journal ◽

10.4314/gm.v21i1.6 ◽

2021 ◽

Vol 21 (1) ◽

pp. 53-67

Author(s):

F. Krampah ◽

N. Amegbey ◽

S. Ndur

Keyword(s):

Particle Size ◽

Particulate Matter ◽

Particle Size Distribution ◽

Size Distribution ◽

Temporal Distribution ◽

Risk Level ◽

Concentration Data ◽

Risk Levels ◽

Spatio Temporal ◽

Monitoring Stations

Particulate matter (PM) varies significantly in space and time. Effective PM risk analysis requires adequate knowledge of the spatial and temporal distribution of PM. In order to understand TSP/PM10 variability within the microclimate of Tarkwa and their potential impact. The Spatio-temporal distribution of Total Suspended Particulates (TSP) and PM10 in Tarkwa was studied. Five years TSP and PM10 monthly concentration data from fifteen (15) monitoring stations were collected and analysed for Spatio-temporal characteristics within the suburbs around three mining companies in Tarkwa. Autocorrelation between neighbouring suburbs, attainment rate, particle size distribution and risk levels were evaluated. The results revealed that all the monitoring stations except two (stations NV and TN) recorded TSP and PM10 concentrations below the national guideline for all years of study. Geo-spatially, highest TSP and PM10 risk level were recorded East of Tarkwa. Inhalable particles constitute about 44.09-72.90% of TSP. Attainment values between 44.09%-100% and 30%-100% were recorded for TSP and PM10, respectively. Estimated AQI values ranged between good and unhealthy for sensitive groups. Future studies directed at the chemical composition of PM was recommended to enhance further understanding of the risk levels. Keywords: Particulate Matter, Attainment Rate, Air Pollution, Trends, Particle Size Distribution

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The Spatio-Temporal Distribution of Particulate Matter during Natural Dust Episodes at an Urban Scale

PLoS ONE ◽

10.1371/journal.pone.0160800 ◽

2016 ◽

Vol 11 (8) ◽

pp. e0160800 ◽

Cited By ~ 10

Author(s):

Helena Krasnov ◽

Itai Kloog ◽

Michael Friger ◽

Itzhak Katra

Keyword(s):

Particulate Matter ◽

Temporal Distribution ◽

Spatio Temporal

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Harmattan, Saharan heat low and West African Monsoon circulation: Modulations on the Saharan dust outflow towards the north Atlantic

10.5194/acp-2017-309 ◽

2017 ◽

Author(s):

Kerstin Schepanski ◽

Bernd Heinold ◽

Ina Tegen

Keyword(s):

North Atlantic ◽

Dust Emission ◽

Temporal Distribution ◽

Saharan Dust ◽

Monsoon Circulation ◽

North African ◽

Dust Source ◽

The North ◽

The North Atlantic ◽

Spatio Temporal

Abstract. The outflow of dust from the North African continent towards the north Atlantic is stimulated by the atmospheric circulation over North Africa, which modulates the spatio-temporal distribution of dust source activation and consequently the entrainment of mineral dust into the boundary layer, as well as the transport of dust out of the source regions. The atmospheric circulation over the North African dust source regions, predominantly the Sahara and the Sahel, is characterised by three major circulation regimes: (1) the Harmattan (trade winds), (2) the Saharan heat low (SHL), and (3) the West African Monsoon circulation. The strength of the individual regimes controls the Saharan dust outflow by affecting the spatio-temporal distribution of dust emission, transport pathways, and deposition fluxes. This study aims at investigating the atmospheric circulation pattern over North Africa with regard to its role favouring dust emission and dust export towards the tropical North Atlantic. The focus of the study is on summer 2013 (June to August), during which also the SALTRACE (Saharan Aerosol Long-range TRansport and Aerosol-Cloud interaction Experiment) field campaign took place. It involves satellite observations by the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) flying on-board the geostationary Meteosat Second Generation (MSG) satellite, which are analysed and used to infer a data set of active dust sources. The spatio-temporal distribution of dust source activation frequencies (DSAF) allows for linking the diurnal cycle of dust source activations to dominant meteorological controls on dust emission. In summer, Saharan dust source activations clearly differ from dust source activations over the Sahel regarding the time-of-day when dust emission begins. The Sahara is dominated by morning dust source activations predominantly driven by the break-down of the nocturnal low-level jet. In contrast, dust source activations in the Sahel are predominantly activated during the second half of the day when down-drafts associated with deep moist convection are the major atmospheric driver. Complementary to the satellite-based analysis on dust source activations and implications from their diurnal cycle, simulations on atmosphere and dust life-cycle were performed using the meso-scale atmosphere-dust model system COSMO-MUSCAT (COSMO: COnsortium for Small-scale MOdelling; MUSCAT: MUltiScale Chemistry Aerosol Transport Model). Fields from this simulation were analysed regarding the variability of the Harmattan, the Saharan heat low, and the Monsoon circulation as well as their impact on the variability of the Saharan dust outflow towards the north Atlantic. This study illustrates the complexity of the interaction among the three major circulation regimes and their modulation of the North African dust outflow. Enhanced westward dust fluxes frequently appear following a phase characterised by a deep SHL. Ultimately, findings from this study contribute to the quantification of the interannual variability of the atmospheric dust burden.

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Variability in atmospheric circulation and moisture flux over the Arctic

Philosophical Transactions of the Royal Society of London Series A Physical and Engineering Sciences ◽

10.1098/rsta.1995.0065 ◽

1995 ◽

Vol 352 (1699) ◽

pp. 215-225 ◽

Cited By ~ 16

Keyword(s):

Water Vapour ◽

North Atlantic ◽

Temporal Distribution ◽

Local Maximum ◽

Precipitable Water ◽

Moisture Flux ◽

The Arctic ◽

Polar Cap ◽

Arctic Water ◽

Spatio Temporal

Mean characteristics and variability in the spatio-temporal distribution of Arctic water vapour and vapour fluxes are examined using several different rawinsondederived databases. Precipitable water averaged over the polar cap, 70-90° N, peaks in July at 14.0 mm. Large poleward fluxes near the prime meridian reflect transport associated with north Atlantic cyclones and, for most months, a local maximum in available water vapour. The mean vapour flux convergence averaged for the polar cap peaks in September. There is a mean annual excess of precipitation minus evaporation ( P — E ) of 163 mm, with a 78 mm range between extreme years. High P — E is favoured by a meridional circulation accompanied by a more dominant North Atlantic cyclone track. No trend in annual P — E is apparent over the 1974-1991 period.

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Harmattan, Saharan heat low, and West African monsoon circulation: modulations on the Saharan dust outflow towards the North Atlantic

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-10223-2017 ◽

2017 ◽

Vol 17 (17) ◽

pp. 10223-10243 ◽

Cited By ~ 26

Author(s):

Kerstin Schepanski ◽

Bernd Heinold ◽

Ina Tegen

Keyword(s):

North Atlantic ◽

Dust Emission ◽

Temporal Distribution ◽

Saharan Dust ◽

Monsoon Circulation ◽

Dust Source ◽

The North ◽

The North Atlantic ◽

Spatio Temporal ◽

Heat Low

Abstract. The outflow of dust from the northern African continent towards the North Atlantic is stimulated by the atmospheric circulation over North Africa, which modulates the spatio-temporal distribution of dust source activation and consequently the entrainment of mineral dust into the boundary layer, as well as the transport of dust out of the source regions. The atmospheric circulation over the North African dust source regions, predominantly the Sahara and the Sahel, is characterized by three major circulation regimes: (1) the harmattan (trade winds), (2) the Saharan heat low (SHL), and (3) the West African monsoon circulation. The strength of the individual regimes controls the Saharan dust outflow by affecting the spatio-temporal distribution of dust emission, transport pathways, and deposition fluxes.This study aims at investigating the atmospheric circulation pattern over North Africa with regard to its role favouring dust emission and dust export towards the tropical North Atlantic. The focus of the study is on summer 2013 (June to August), during which the SALTRACE (Saharan Aerosol Long-range TRansport and Aerosol-Cloud interaction Experiment) field campaign also took place. It involves satellite observations by the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) flying on board the geostationary Meteosat Second Generation (MSG) satellite, which are analysed and used to infer a data set of active dust sources. The spatio-temporal distribution of dust source activation frequencies (DSAFs) allows for linking the diurnal cycle of dust source activations to dominant meteorological controls on dust emission. In summer, Saharan dust source activations clearly differ from dust source activations over the Sahel regarding the time of day when dust emission begins. The Sahara is dominated by morning dust source activations predominantly driven by the breakdown of the nocturnal low-level jet. In contrast, dust source activations in the Sahel are predominantly activated during the second half of the day, when downdrafts associated with deep moist convection are the major atmospheric driver. Complementary to the satellite-based analysis on dust source activations and implications from their diurnal cycle, simulations on atmosphere and dust life cycle were performed using the mesoscale atmosphere–dust model system COSMO-MUSCAT (COSMO: COnsortium for Small-scale MOdelling; MUSCAT: MUltiScale Chemistry Aerosol Transport Model). Fields from this simulation were analysed regarding the variability of the harmattan, the Saharan heat low, and the monsoon circulation as well as their impact on the variability of the Saharan dust outflow towards the North Atlantic. This study illustrates the complexity of the interaction among the three major circulation regimes and their modulation of the North African dust outflow. Enhanced westward dust fluxes frequently appear following a phase characterized by a deep SHL. Ultimately, findings from this study contribute to the quantification of the interannual variability of the atmospheric dust burden.

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