scholarly journals Atmospheric dynamics over northwest Africa and linkages with Sahelian rainfall

2006 ◽  
Vol 33 (14) ◽  
Author(s):  
Yves M. Tourre ◽  
Shlomit Paz ◽  
Christophe Cassou ◽  
Haim Kutiel
Keyword(s):  
Atmospheric Dynamics ◽  
Northwest Africa ◽  
Sahelian Rainfall

LITHOLOGIC DIVERSITY WITHIN LUNAR REGOLITH BRECCIA METEORITE NORTHWEST AFRICA 8783: CLASTS 3 AND 6

2020 ◽  
Author(s):  
Cecillia Utterback ◽  
◽  
Madi Hall ◽  
Erin M. Recchuiti ◽  
Amy L. Fagan
Keyword(s):  
Lunar Regolith ◽  
Northwest Africa

scholarly journals Molecular Species Delimitation of Larks (Aves: Alaudidae), and Integrative Taxonomy of the Genus Calandrella, with the Description of a Range-Restricted African Relic Taxon

Diversity ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 428
Author(s):  
Martin Stervander ◽  
Bengt Hansson ◽  
Urban Olsson ◽  
Mark F. Hulme ◽  
Ulf Ottosson ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Molecular Species ◽  
Species Delimitation ◽  
Integrative Taxonomy ◽  
West African ◽  
Northwest Africa ◽  
Sub Saharan ◽  
Plateau State ◽  
Avian Family ◽  
Relic Population

Larks constitute an avian family of exceptional cryptic diversity and striking examples of convergent evolution. Therefore, traditional morphology-based taxonomy has recurrently failed to reflect evolutionary relationships. While taxonomy ideally should integrate morphology, vocalizations, behaviour, ecology, and genetics, this can be challenging for groups that span several continents including areas that are difficult to access. Here, we combine morphometrics and mitochondrial DNA to evaluate the taxonomy of Calandrella larks, with particular focus on the African C. cinerea and the Asian C. acutirostris complexes. We describe a new range-restricted West African taxon, Calandrella cinerea rufipecta ssp. nov. (type locality: Jos, Plateau State, Nigeria), with an isolated relic population 3000 km from its closest relative in the Rift Valley. We performed molecular species delimitation, employing coalescence-based multi-rate Poisson Tree Processes (mPTP) on cytochrome b sequences across 52 currently recognized lark species, including multiple taxa currently treated as subspecies. Three species-level splits were inferred within the genus Calandrella and another 13 across other genera, primarily among fragmented sub-Saharan taxa and taxa distributed from Northwest Africa to Arabia or East Africa. Previously unknown divergences date back as far as to the Miocene, indicating the presence of currently unrecognized species. However, we stress that taxonomic decisions should not be based on single datasets, such as mitochondrial DNA, although analyses of mitochondrial DNA can be a good indicator of taxa in need of further integrative taxonomic assessment.

scholarly journals Cuttlebone morphometrics and sex identification of Sepia bertheloti (d’Orbigny, 1835) from the central-east Atlantic

2019 ◽  
Vol 73 (1) ◽  
Author(s):  
Airam Guerra-Marrero ◽  
David Jiménez-Alvarado ◽  
Vicente Hernández-García ◽  
Leticia Curbelo-Muñoz ◽  
José Juan Castro-Hernández
Keyword(s):  
Morphometric Analysis ◽  
Growth Pattern ◽  
Gonadal Development ◽  
Sex Identification ◽  
East Atlantic ◽  
Subsequent Increase ◽  
Northwest Africa ◽  
Males And Females

Abstract Analysis of 322 cuttlebones of Sepia bertheloti caught in the waters of the Northwest Africa showed significant differences in growth between males and females. Morphometric analysis revealed a relatively different cuttlebone growth pattern between sexes, with males presenting faster growth in length to reach larger sizes and females displaying greater growth in width. This difference in cuttlebone growth is related to female gonadal development and the subsequent increase of the paleal cavity, providing more support and space to accommodate a higher number of oocytes.

Seismic geomorphology of early North Atlantic sediment waves, offshore northwest Africa

2013 ◽  
Vol 1 (1) ◽  
pp. SA75-SA91 ◽  
Author(s):  
Dallas B. Dunlap ◽  
Lesli J. Wood ◽  
Lorena G. Moscardelli
Keyword(s):  
Seismic Survey ◽  
Entire Study ◽  
Sediment Waves ◽  
Northwest Africa ◽  
Stable Slope ◽  
Wave Forms ◽  
History Of ◽  
Wave Heights ◽  
Slope Currents ◽  
Mass Transport Deposits

The lower continental rise of Morocco’s Atlantic Margin contains three varying morphologies of buried deepwater sediment waves. The 3D mapping of a [Formula: see text] seismic survey acquired in the Safi Haute Mer seismic block revealed numerous linear features that range from small, less than 17-m-thick Jurassic-age amplitude striations up to 110-m-thick migrating Cretaceous contourite sediment waves. Early proto-Atlantic deposition in Safi Haute Mer initiated in the Triassic, with syn- and postrift accumulation in basement half-grabens basinward of the modern Moroccan salt front. Sedimentation continued through the Mesozoic with deposition of turbidites, progradation of clinoforms, and culminating in multiple Late Cretaceous, regionally expansive, mass-transport deposits ([Formula: see text]). Tertiary stratigraphy consists of multiple thin, pelagic drapes and unconformities. The complex history of sedimentation and tectonics gave rise to three styles of sediment waves found within the study area: (1) type J1 — small and poorly imaged, Jurassic age, locally generated wave forms that have wavelengths of up to 12 km and crest-to-crest separations of less than 1 km with little or no vertical expression; (2) type K1 — early Aptian constructional sediment waves ([Formula: see text] thick) built by contour currents that traveled in and near a contourite moat at the base of a seafloor high produced by shallowly buried mobile salt; and (3) type K2 — latest Albian and earliest post-Albian sediment waves built by along-slope currents on a relatively stable slope, showing evidence of updip migration. The type K2 sediment wavefield exhibits wave heights of 40 m and crest-to-crest separations of 1 km, and it is continuous over the entire study area.

scholarly journals Effects of atmospheric dynamics and aerosols on the fraction of supercooled water clouds

2017 ◽  
Vol 17 (3) ◽  
pp. 1847-1863 ◽  
Author(s):  
Jiming Li ◽  
Qiaoyi Lv ◽  
Min Zhang ◽  
Tianhe Wang ◽  
Kazuaki Kawamoto ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Vertical Velocity ◽  
Meteorological Parameters ◽  
Temporal Correlation ◽  
Supercooled Liquid ◽  
Satellite Observation ◽  
Static Stability ◽  
Global Scale ◽  
Atmospheric Dynamics ◽  
Horizontal Wind

Abstract. Based on 8 years of (January 2008–December 2015) cloud phase information from the GCM-Oriented Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) Cloud Product (GOCCP), aerosol products from CALIPSO and meteorological parameters from the ERA-Interim products, the present study investigates the effects of atmospheric dynamics on the supercooled liquid cloud fraction (SCF) during nighttime under different aerosol loadings at global scale to better understand the conditions of supercooled liquid water gradually transforming to ice phase. Statistical results indicate that aerosols' effect on nucleation cannot fully explain all SCF changes, especially in those regions where aerosols' effect on nucleation is not a first-order influence (e.g., due to low ice nuclei aerosol frequency). By performing the temporal and spatial correlations between SCFs and different meteorological factors, this study presents specifically the relationship between SCF and different meteorological parameters under different aerosol loadings on a global scale. We find that the SCFs almost decrease with increasing of aerosol loading, and the SCF variation is closely related to the meteorological parameters but their temporal relationship is not stable and varies with the different regions, seasons and isotherm levels. Obviously negative temporal correlations between SCFs versus vertical velocity and relative humidity indicate that the higher vertical velocity and relative humidity the smaller SCFs. However, the patterns of temporal correlation for lower-tropospheric static stability, skin temperature and horizontal wind are relatively more complex than those of vertical velocity and humidity. For example, their close correlations are predominantly located in middle and high latitudes and vary with latitude or surface type. Although these statistical correlations have not been used to establish a certain causal relationship, our results may provide a unique point of view on the phase change of mixed-phase cloud and have potential implications for further improving the parameterization of the cloud phase and determining the climate feedbacks.

Tropical Pacific internal atmospheric dynamics and resolution in a coupled GCM

2014 ◽  
Vol 44 (1-2) ◽  
pp. 509-527 ◽  
Author(s):  
Hosmay Lopez ◽  
Ben P. Kirtman
Keyword(s):  
Tropical Pacific ◽  
Atmospheric Dynamics ◽  
Coupled Gcm
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