Control of Saharan mineral dust transport to Barbados in winter by the Intertropical Convergence Zone over West Africa

2012 ◽  
Vol 117 (D19) ◽  
pp. n/a-n/a ◽  
Author(s):  
O. M. Doherty ◽  
N. Riemer ◽  
S. Hameed
Keyword(s):  
West Africa ◽  
Mineral Dust ◽  
Intertropical Convergence Zone ◽  
Convergence Zone ◽  
Dust Transport

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

Tellus B ◽  
2014 ◽  
Vol 66 (1) ◽  
pp. 23191 ◽  
Author(s):  
Owen M. Doherty ◽  
Nicole Riemer ◽  
Sultan Hameed
Keyword(s):  
West Africa ◽  
Mineral Dust ◽  
Boreal Summer ◽  
Convergence Zone ◽  
Dust Load

OH measurement near the Intertropical Convergence Zone in the Pacific

1987 ◽  
Vol 92 (D2) ◽  
pp. 2020 ◽  
Author(s):  
L. I. Davis ◽  
John V. James ◽  
Charles C. Wang ◽  
Chuan Guo ◽  
Peter T. Morris ◽  
...  
Keyword(s):  
Intertropical Convergence Zone ◽  
Convergence Zone ◽  
The Pacific

scholarly journals Dynamics of the Intertropical Convergence Zone of the East Pacific

2006 ◽  
Vol 63 (2) ◽  
pp. 582-597 ◽  
Author(s):  
David J. Raymond ◽  
Christopher S. Bretherton ◽  
John Molinari
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Flow ◽  
Deep Convection ◽  
Intertropical Convergence Zone ◽  
Surface Fluxes ◽  
Balance Model ◽  
Convergence Zone ◽  
East Pacific ◽  
Layer Flow ◽  
Sst Gradient

Abstract The dynamical factors controlling the mean state and variability of the east Pacific intertropical convergence zone (ITCZ) and the associated cross-equatorial boundary layer flow are investigated using observations from the East Pacific Investigation of Climate (EPIC2001) project. The tropical east Pacific exhibits a southerly boundary layer flow that terminates in the ITCZ. This flow is induced by the strong meridional sea surface temperature (SST) gradient in the region. Away from the equator and from deep convection, it is reasonably well described on a day-to-day basis by an extended Ekman balance model. Variability in the strength and northward extent of this flow is caused by variations in free-tropospheric pressure gradients that either reinforce or oppose the pressure gradient associated with the SST gradient. These free-tropospheric gradients are caused by easterly waves, tropical cyclones, and the Madden–Julian oscillation. Convergence in the boundary layer flow is often assumed to be responsible for destabilizing the atmosphere to deep convection. An alternative hypothesis is that enhanced total surface heat fluxes associated with high SSTs and strong winds act to produce the necessary destabilization. Analysis of the moist entropy budget of the planetary boundary layer shows that, on average, surface fluxes generate over twice the destabilization produced by boundary layer convergence in the east Pacific ITCZ.

Studies of winds and weather during migrations of Simulium damnosum Theobald (Diptera: Simuliidae), the vector of onchocerciasis in West Africa

1980 ◽  
Vol 70 (4) ◽  
pp. 693-716 ◽  
Author(s):  
J. I. Magor ◽  
L. J. Rosenberg
Keyword(s):  
West Africa ◽  
Time Of Arrival ◽  
Convergence Zone ◽  
Gonotrophic Cycle ◽  
Inter Tropical Convergence Zone ◽  
The North ◽  
Simulium Damnosum ◽  
Host Seeking ◽  
First Time ◽  
High Winds

AbstractReports of the presence and absence of biting by Simulium damnosum Theo. in the Volta River Basin in 1962, 1966 and 1975 were used to identify occasions when sites were invaded by parous and nulliparous females. Circumstantial evidence suggests that this insect is a wind-borne migrant, and the weather before and during some of these invasions was examined. Although most invasions studied took place south of the Inter-tropical Convergence Zone, for the first time evidence is presented suggesting that migration also takes place to the north of this zone. Immigrants were captured at the invaded sites only when light winds or calms were present. This cannot, however, be used as proof that S. damnosum migrates and lands only where winds are light or it is calm because host-seeking is inhibited by high winds and the time of arrival, as opposed to capture on a host, is unknown. Until the factors initiating emigration, as well as the height, duration and number of flights in each gonotrophic cycle and the time of immigration are known, the present findings cannot be tested rigorously nor can wind records be used to trace the source of immigrants.

The Intertropical Convergence Zone

2013 ◽  
pp. 35-46
Author(s):  
T. N. Krishnamurti ◽  
Lydia Stefanova ◽  
Vasubandhu Misra
Keyword(s):  
Intertropical Convergence Zone ◽  
Convergence Zone

scholarly journals Three distinct Holocene intervals of stalagmite deposition and nondeposition revealed in NW Madagascar, and their paleoclimate implications

2017 ◽  
Vol 13 (12) ◽  
pp. 1771-1790 ◽  
Author(s):  
Ny Riavo Gilbertinie Voarintsoa ◽  
Loren Bruce Railsback ◽  
George Albert Brook ◽  
Lixin Wang ◽  
Gayatri Kathayat ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
High Resolution ◽  
Late Holocene ◽  
Intertropical Convergence Zone ◽  
Convergence Zone ◽  
High Resolution Data ◽  
The Holocene ◽  
Middle Holocene ◽  
Resolution Data

Abstract. Petrographic features, mineralogy, and stable isotopes from two stalagmites, ANJB-2 and MAJ-5, respectively from Anjohibe and Anjokipoty caves, allow distinction of three intervals of the Holocene in NW Madagascar. The Malagasy early Holocene (between ca. 9.8 and 7.8 ka) and late Holocene (after ca. 1.6 ka) intervals (MEHI and MLHI, respectively) record evidence of stalagmite deposition. The Malagasy middle Holocene interval (MMHI, between ca. 7.8 and 1.6 ka) is marked by a depositional hiatus of ca. 6500 years. Deposition of these stalagmites indicates that the two caves were sufficiently supplied with water to allow stalagmite formation. This suggests that the MEHI and MLHI intervals may have been comparatively wet in NW Madagascar. In contrast, the long-term depositional hiatus during the MMHI implies it was relatively drier than the MEHI and the MLHI. The alternating wet–dry–wet conditions during the Holocene may have been linked to the long-term migrations of the Intertropical Convergence Zone (ITCZ). When the ITCZ's mean position is farther south, NW Madagascar experiences wetter conditions, such as during the MEHI and MLHI, and when it moves north, NW Madagascar climate becomes drier, such as during the MMHI. A similar wet–dry–wet succession during the Holocene has been reported in neighboring locations, such as southeastern Africa. Beyond these three subdivisions, the records also suggest wet conditions around the cold 8.2 ka event, suggesting a causal relationship. However, additional Southern Hemisphere high-resolution data will be needed to confirm this.

scholarly journals Climatologia da pluviometria do município de Teresina, Piauí, Brasil

2016 ◽  
Vol 11 (4) ◽  
pp. 135
Author(s):  
Hudson Ellen Alencar Menezes ◽  
Raimundo Mainar de Medeiros ◽  
José Lucas Guilherme Santos
Keyword(s):  
Water Resources ◽  
Rainfall Variability ◽  
Intertropical Convergence Zone ◽  
Atmospheric Dynamics ◽  
Rainfall Data ◽  
Annual Rainfall ◽  
Convergence Zone ◽  
Northeast Brazil ◽  
Urban Structures ◽  
Urbanized Areas

<p>As variações nas precipitações refletem claramente a dinâmica atmosférica da região, marcada pela intensa variabilidade, onde se observa a atuação da Zona de Convergência Intertropical (ZCIT) com sua atuação entre os meses de janeiro a março, sendo esse período mais chuvoso. As variabilidades espaço temporal no comportamento das chuvas tem sido analisadas e diagnosticadas por vários autores no Nordeste do Brasil (NEB), portanto objetivou-se diagnosticar a variabilidade dos índices pluviométricos em Teresina no Estado do Piauí no período de 1913 a 2010. A análise do comportamento da precipitação nas cidades de grande e médio porte é de extrema importância para o gerenciamento dos recursos hídricos, uma vez que se trata de áreas densamente urbanizadas. Muitas vezes, sem uma estruturação urbana adequada, estas cidades se encaixam perfeitamente nesse contexto. Foram utilizados dados mensais observados e anuais de precipitação pluviométrica no período de 1913 a 2010, com 97 anos de observações. Os resultados mostraram a recorrência de valores máximos de precipitação anual dentro de um intervalo de 18, 11 e 8 anos. Na análise dos desvios-padrões, os resultados mostraram predominância dos desvios negativos em relação aos desvios positivos.</p><p align="center"><strong><em>Climatology of rainfall in the Teresina city, Piauí state, Brazil</em></strong></p><p>Variations in precipitation clearly reflect the atmospheric dynamics of the region, marked by intense variability, where we observe the performance of the Intertropical Convergence Zone (ITCZ) with his performance in the months of January-March, this being more rain tem period. The timeline of rainfall variability in behavior has been analyzed and diagnosed by several authors in Northeast Brazil (NEB), so let's study this variability between the periods 1913 to 2010 of Teresina city.  The behavior of rainfall in cities large and medium sized is of utmost importance to the managerial of water resources, since it is densely urbanized areas. Often without adequate urban structures these cities fit perfectly in this context. We used observed monthly and annual rainfall data for the period 1913-2010, 97 years of observations. The results showed recurrence of maximum values of annual precipitation an interval of 18, 11 and 8 years. In the analysis of standard deviations, the results showed a predominance of negative deviations from the positive deviations.<strong></strong></p><p align="center"><strong><em><br /></em></strong></p>

Sign in / Sign up

Export Citation Format

Share Document