The synoptic and optical characteristics of the harmattan dust spells over Nigeria

Ogunjobi, K. O.; Ajayi, V.; Balogun, Ifeoluwa Adebowale; Omotosho, J. Bayo; Zhao, He

doi:10.1007/s00704-007-0332-2

Cited by 16 publications

(19 citation statements)

References 37 publications

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“…ACS was the second common acute vaso-occlusive morbidity, which showed a peak in its monthly frequency during the month of December in the middle of the harmattan dry season. The harmattan season is characterized by low ambient temperatures, low relative humidity, dusty winds and atmospheric pollution [2, 3,5,24]. These conditions are optimally conducive for acquisition and spread of allergic and infectious diseases of the respiratory system within the community [25].…”

Section: Discussionmentioning

confidence: 99%

Seasonal Variations in Frequencies of Acute Vaso-Occlusive Morbidities among Sickle Cell Anaemia Patients in Northern Nigeria

Ahmed¹,

Kagu²,

Abjah³

et al. 2012

J Blood Disord Transfus

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Background: Nigeria is the most populous black nation with the heaviest burden of Sickle Cell Anaemia divided into a cold and dusty harmattan season and a hot non-harmattan dry season. We studied the impact of seasonal variations of climatic factors on the frequencies of acute vaso-occlusive morbidities, including Vaso-Occlusive Crisis (VOC), Acute Chest Syndrome (ACS), priapism and stroke among patients with SCA in northern Nigeria.Methods: This is a six-year prospective study conducted from 2005 to 2010 in university teaching hospitals of Maiduguri and Kano cities of northern Nigeria. Consecutive patients with SCA who presented with VOC, ACS, priapism and stroke were diagnosed, recruited and enumerated. The monthly and seasonal frequencies of each morbidity (VOC, ACS, priapism or stroke) during the period of study were calculated and graphically evaluated. Results:The frequencies of VOC showed 3 peaks: during the harmattan dry season in January, during the non-harmattan dry season in April and during the rainy season in August. The frequencies of ACS showed a peak during the harmattan dry season in December. The frequencies of priapism showed a peak during the nonharmattan dry season in April. The frequencies of stroke showed a peak during the rainy season in July/August. Conclusion:The frequencies of acute vaso-occlusive morbidities in SCA patients could be adversely affected by seasonal variations in climatic factors. There is need for patients and care givers to be adequately educated on how to mitigate the adverse effects of weather on SCA. Moreover, governmental and non-governmental organizations should take seasonal variations of climatic factors into consideration when drafting health care plan for patients with SCA.(SCA). The climate in the north is characterized by a short rainy season and a long dry season that can be sub- Journal of Blood Disorders & TransfusionJ ou rnal of B lo o d Dis orde rs & Tr ans fusi on

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Section: Discussionmentioning

confidence: 99%

Seasonal Variations in Frequencies of Acute Vaso-Occlusive Morbidities among Sickle Cell Anaemia Patients in Northern Nigeria

Ahmed¹,

Kagu²,

Abjah³

et al. 2012

J Blood Disord Transfus

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“…A ground-based AERONET sun photometer sensors are situated at the AERONET observation site located in Ilorin on latitude 8˚32'N and longitude 4˚34'E, Nigeria; detail description of the study site can be found in Nwafor et al [3] and Ogunjobi et al [9] while the instrument was described in detail by Holben et al [20]. Direct sun-photometer measures solar attenuation and sky brightness every 15 minutes at 340, 380, 440, 500, 675, 870, 940, and 1020 nm (including the 1640 nm channel in Cimel version 5).…”

Section: Methodsmentioning

confidence: 99%

“…The seasonal dependence of AOD has resulted in the corresponding seasonal feature of angstrom exponent discussed below. The lowest values of mean α observed between March and May is a signature of mineral dust [9]. It increases from May until the peak is reached in August due to large and frequent rainfall [27] as a result of which significant amount of the larger particles are washed down from the atmosphere.…”

Section: Aerosol Climatology Of Ilorin Nigeriamentioning

confidence: 99%

“…Furthermore, aerosol concentration in the atmosphere has also been reported to affect air quality and human health [7] [8]. Aerosol causes indirect effect by increasing cloud condensation nuclei and consequently to larger concentrations of cloud droplet with small radii [9]. It is established that quantifications of these effects become difficult due to their types (as a result of their variety of sources), varying pattern and interaction among each other [10] [11].…”

Section: Introductionmentioning

confidence: 99%

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Seasonal Variations of Aerosol Optical Properties and Identification of Different Aerosol Types Based on AERONET Data over Sub-Sahara West-Africa

Balarabe

Abdullah

Adlan

2016

ACS

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The uncertainty in the quantification of aerosol properties such as concentration, size, and composition, spatially and temporally makes regional studies important. Therefore, this study presents seasonal variations of aerosol optical properties over Ilorin (8˚32'N, 4˚34'E), Nigeria. Long-term (1998-2013) records of aerosol optical depth (AOD) and angstrom exponent α, from ground-based Aerosol Robotic Network (AERONET) are used to study the seasonal variability, characteristics and types of aerosol. The study showed that seasonal variations (Harmattan and Summer) result in different aerosol concentration, characteristics, and types. The magnitude and sensitivity of AOD to wavelength are found low in Summer with significant increase during Saharan dust transport season (Harmattan). The average mean AODs are 0.73 ± 0.50, 0.97 ± 0.52 and 0.46 ± 0.29 with corresponding mean angstrom of 0.66 ± 0.36, 0.68 ± 0.34, and 0.64 ± 0.37 for the entire period, Harmattan and Summer seasons. High frequency of occurrence of angstrom exponent below 1 (78% and 81%) which were observed during Harmattan and Summer indicates that the particles are generally coarse in mode. The results revealed that for both Harmattan and Summer seasons, the dominant aerosol was dust (DA) with frequency of occurrence of 82% and 79%. However, mixed aerosol (MIXA) (14.4%) is the second dominant case during Harmattan while in Summer maritime aerosol (MA) (9.1%) associated with transport due to southwesterly trade wind is the second dominant aerosol. This conclusion is supported by size distribution data for the study site which showed that large volume of aerosol particle size are enclosed in largely coarse mode range in all seasons. A 7-day back trajectory seasonal frequency plot sourced from the Hysplit Single Particles Lagrangian Integrated Trajectory model (Hysplit_4 model) shows that dust are transported from the Saha-* Corresponding author. ra during north-easterly trade wind flow while the observed marine aerosols are conveyed by the southwesterly trade wind influences to the study site.

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“…Além disso, a concentração de aerossol na atmosfera também pode afetar a qualidade do ar e da saúde humana (FLORENCE, YVON, et al, 2010). Os aerossóis provocam efeitos diretos, aumentando os núcleos de condensação de nuvens e, consequentemente, maior concentração de nuvem (OGUNJOKI, AJAYI, et al, 2008). A quantificação desses efeitos torna-se difícil devido aos tipos de particulado (resultado da sua variedade de fontes), o padrão e as interações existentes (HABID, VENKATARAMAN, et al, 2006).…”

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Climatologia Da Profundidade Ótica E Dependência Espectral De Aerossóis Em Regiões De Floresta E Cerrado No Brasil

Menezes

Palácios

Menezes

et al. 2018

ABClima

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Aerossóis atmosféricos desempenham um papel importante no equilíbrio de energia do sistema Terra-atmosfera. Medidas de aerossóis foram realizadas em quatro sítios, dois em área de floresta (Rio Branco e Ji-Paraná) e dois em área de Cerrado (Cuiabá e Campo Grande), utilizando fotômetro solar da rede global AERONET. Dados de 5 anos permitiram classificar as propriedades óticas dos aerossóis, definindo a climatologia para cada sítio. Neste trabalho a profundidade óptica de aerossol (AOD 440nm) e expoente Angstrom, α(440-870), foram utilizados para a análise espectral de aerossol. Médias de AOD(440nm) para sítios de Cerrado foram, respectivamente, 0,29 (±0,40), 0,18(±0,24), com média correspondente de α 1,20(±0,39), 1,16(±0,36). Médias de AOD(440nm) para sítios de Floresta são, respectivamente, 0,85(±0,71), 0,35(±0,44), com média correspondente de α 1,38(±0,41), 1,40(±0,34). A AOD(440nm) tanto para regiões de Cerrado como de Floresta mostram picos distintos para estação seca e chuvosa, sendo que estão relacionados com padrões sazonais de aerossóis característicos dessas regiões. O α (440-870) apresentou modos de frequência que relacionam-se com os principais tipos de aerossóis presentes tanto em Cerrado como em Floresta. Um cenário principal de aerossóis foi definido como aerossóis oriundos de queima de biomassa, com forte influência de fontes locais de aerossóis poluídos. Mistura de aerossóis estão presentes, enquanto que poeira em suspensão tem uma ocorrência pouco relevante.

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The synoptic and optical characteristics of the harmattan dust spells over Nigeria

Cited by 16 publications

References 37 publications

Seasonal Variations in Frequencies of Acute Vaso-Occlusive Morbidities among Sickle Cell Anaemia Patients in Northern Nigeria

Seasonal Variations in Frequencies of Acute Vaso-Occlusive Morbidities among Sickle Cell Anaemia Patients in Northern Nigeria

Seasonal Variations of Aerosol Optical Properties and Identification of Different Aerosol Types Based on AERONET Data over Sub-Sahara West-Africa

Climatologia Da Profundidade Ótica E Dependência Espectral De Aerossóis Em Regiões De Floresta E Cerrado No Brasil

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