scholarly journals Comparing Rural Multilingualism in Lowland South America and Western Africa

2020 ◽  
Vol 62 (1) ◽  
pp. 3-57
Author(s):  
Friederike Lüpke ◽  
Kristine Stenzel ◽  
Flora Dias Cabalzar ◽  
Thiago Chacon ◽  
Aline da Cruz ◽  
...  
Keyword(s):  
South America ◽  
Western Africa

A new Hispid Beetle injurious to Oil Palms in Brazil

1924 ◽  
Vol 14 (3) ◽  
pp. 245-246 ◽  
Author(s):  
S. Maulik
Keyword(s):  
South America ◽  
West Indies ◽  
Elaeis Guineensis ◽  
Gulf Of Guinea ◽  
The West ◽  
African Lakes ◽  
Western Africa ◽  
Wide Geographical Distribution ◽  
Oil Palms ◽  
African Oil Palm

Through the courtesy of Dr. G. A. K. Marshall, F.R.S., I have had the opportunity of examining the new beetle, a description of which is given below. It was sent by Dr. G. Bondar to Dr. Marshall as occurring in Brazil on Elaeis guineensis. This plant, the African oil palm, is a native of tropical Western Africa, where it has a wide geographical distribution from the Gulf of Guinea to the South of Fernando Po. It flourishes in the Island of Zanzibar and along the shores of the Central African lakes, and has been introduced into the Philippine Islands, the West Indies and South America.

scholarly journals Improving the taxonomy of fossil pollen using convolutional neural networks and superresolution microscopy

2020 ◽  
Vol 117 (45) ◽  
pp. 28496-28505 ◽  
Author(s):  
Ingrid C. Romero ◽  
Shu Kong ◽  
Charless C. Fowlkes ◽  
Carlos Jaramillo ◽  
Michael A. Urban ◽  
...  
Keyword(s):  
South America ◽  
Taxonomic Resolution ◽  
Fossil Pollen ◽  
Pollen Data ◽  
Deep Time ◽  
Superresolution Microscopy ◽  
Western Africa ◽  
Thermal Maximum ◽  
Biological Affinity

Taxonomic resolution is a major challenge in palynology, largely limiting the ecological and evolutionary interpretations possible with deep-time fossil pollen data. We present an approach for fossil pollen analysis that uses optical superresolution microscopy and machine learning to create a quantitative and higher throughput workflow for producing palynological identifications and hypotheses of biological affinity. We developed three convolutional neural network (CNN) classification models: maximum projection (MPM), multislice (MSM), and fused (FM). We trained the models on the pollen of 16 genera of the legume tribe Amherstieae, and then used these models to constrain the biological classifications of 48 fossilStriatopollisspecimens from the Paleocene, Eocene, and Miocene of western Africa and northern South America. All models achieved average accuracies of 83 to 90% in the classification of the extant genera, and the majority of fossil identifications (86%) showed consensus among at least two of the three models. Our fossil identifications support the paleobiogeographic hypothesis that Amherstieae originated in Paleocene Africa and dispersed to South America during the Paleocene-Eocene Thermal Maximum (56 Ma). They also raise the possibility that at least three Amherstieae genera (Crudia,Berlinia, andAnthonotha) may have diverged earlier in the Cenozoic than predicted by molecular phylogenies.

New simple approach to understand the spatial and vertical distribution of biomass burning CO emission based on the MOPITT vertical measurements

2020 ◽  
Author(s):  
Chuyong Lin ◽  
Jason Cohen
Keyword(s):  
South America ◽  
Biomass Burning ◽  
Large Scale ◽  
Central Africa ◽  
Western Africa ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Significant Spread ◽  
Spatial And Vertical Distribution

<p>A simple variance-maximization approach, based on 19 years of weekly Moderate Resolution Imaging spectroradiometer (MOPITT) CO vertical measurements, was employed to quantify the spatial distribution of the global seasonal biomass burning region. Results demonstrate there are a few large-scale and typical biomass burning regions responsible for most of the biomass burning emissions throughout the world, with the largest of these such regions located in Amazonian South America, Western Africa, Indonesia, and Northern Southeast Asia (Eastern India, Northern Myanmar, Laos, Vietnam and Eastern Bangladesh), which are highly associated with the results of Global Fire Emission Database(GFED). The CO is primarily lofted to and spreads downwind at 800mb or 700mb with three exceptions: The Maritime Continent and South America where there is significant spread at 300mb consistent with known deep- and pyro-convection; and Southern Africa where there is significant spread at 600mb. The total mass of CO lofted into the free troposphere ranges from 46% over Central Africa to 92% over Australia.</p>

Biostratigraphical dating of the early history of the South Atlantic Ocean

1972 ◽  
Vol 264 (858) ◽  
pp. 55-95 ◽  
Keyword(s):  
South America ◽  
Ivory Coast ◽  
Continental Drift ◽  
Periodic Pattern ◽  
Western Africa ◽  
Basement Rocks ◽  
Marine Sedimentation ◽  
Continental Block ◽  
Mid Atlantic Ridge ◽  
Great Rift Valley

The southern Atlantic has always been a favoured testing ground for the hypothesis of continental drift. Apart from the remarkable agreement in the geographical shape of the coast of western Africa and eastern South America, considerable attention has been paid to the origin of the Mid-Atlantic ridge and these factors have provided a basis for testing the concept of drift. Detailed studies of the geology of NE Brazil and Gabon indicate that both areas had been basins of non-marine sedimentation almost continuously from the Upper Palaeozoic through to the Neocomian. During the Neocomian it would appear that both areas were parts of a large freshwater lake which may have been situated in a zone of subsidence produced by an initial phase in the separation of the two land masses. This structure may have been similar to the Great Rift Valley system of today in East Africa. It would seem that the rift continued to widen during the Neocomian and made connexion with the open ocean during the Aptian, thus developing into a ‘protoatlantic’ similar in configuration to the present day Red Sea. During the latter part of the Aptian, salt deposits began to accumulate in the narrower parts of the elongated bays. The deposits in Gabon, Angola and Brazil are large and of economic importance. About this time South America seems to have begun a relative clockwise rotational motion, which in its later stages may have resulted in a fracturing and tearing movement of the crystalline basement rocks in the area bounded by the Ivory Coast and Maranhão. The point in time at which northern and southern arms of the protoatlantic became united may be ascertained by means of a biostratigraphical analysis, based mainly on the evidence provided by the ammonites of the critical sequences. The crucial area lies in a zone formed by the states of Rio Grande do Norte, Pernambuco, Alagoas, Sergipe and Bahia in Brazil, and the Ivory Coast down to Angola and Gabon in West Africa. The analysis of the Albian to Turonian invertebrate associations, in particular the dispersion of the genus Elobiceras and the vascoceratid, pseudotissotiid, mammitid and benueitan faunas shows that the final break between South America and Africa may be dated as upper Lower Turonian. Furthermore, the geographical dispersion of Turonian invertebrates shows that the rifting apart was accompanied by a periodic pattern of regressions and transgressions possibly brought about by oscillatory movements of the continental block.

scholarly journals The seasonal vertical distribution of the Saharan Air Layer and its modulation by the wind

2013 ◽  
Vol 13 (22) ◽  
pp. 11235-11257 ◽  
Author(s):  
C. Tsamalis ◽  
A. Chédin ◽  
J. Pelon ◽  
V. Capelle
Keyword(s):  
South America ◽  
Vertical Distribution ◽  
North Atlantic ◽  
Deposition Velocity ◽  
Dust Particles ◽  
Dust Aerosols ◽  
Saharan Air Layer ◽  
Western Africa ◽  
The North ◽  
The North Atlantic

Abstract. The Saharan Air Layer (SAL) influences large-scale environment from western Africa to eastern tropical Americas, by carrying large amounts of dust aerosols. However, the vertical distribution of the SAL is not well established due to a lack of systematic measurements away from the continents. This can be overcome by using the observations of the spaceborne lidar CALIOP onboard the satellite CALIPSO. By taking advantage of CALIOP's capability to distinguish dust aerosols from other types of aerosols through depolarization, the seasonal vertical distribution of the SAL is analyzed at 1° horizontal resolution over a period of 5 yr (June 2006–May 2011). This study shows that SAL can be identified all year round displaying a clear seasonal cycle. It occurs higher in altitude and more northern in latitude during summer than during winter, but with similar latitudinal extent near Africa for the four seasons. The south border of the SAL is determined by the Intertropical Convergence Zone (ITCZ), which either prohibits dust layers from penetrating it or reduces significantly the number of dust layers seen within or south of it, as over the eastern tropical Atlantic. Spatially, near Africa, it is found between 5° S and 15° N in winter and 5–30° N in summer. Towards the Americas (50° W), SAL is observed between 5° S and 10° N in winter and 10–25° N in summer. During spring and fall, SAL is found between the position of winter and summer not only spatially but also vertically. In winter, SAL occurs in the altitude range 0–3 km off western Africa, decreasing to 0–2 km close to South America. During summer, SAL is found to be thicker and higher near Africa at 1–5 km, reducing to 0–2 km in the Gulf of Mexico, farther west than during the other seasons. SAL is confined to one layer, of which the mean altitude decreases with westward transport by 13 m deg−1 during winter and 28 m deg−1, after 30° W, during summer. Its mean geometrical thickness decreases by 25 m deg−1 in winter and 9 m deg−1 in summer. Spring and fall present similar characteristics for both mean altitude and geometrical thickness. Wind plays a major role not only for the transport of dust within the SAL but also by sculpting it. During winter, the trade winds transport SAL towards South America, while in spring and summer they bring dust-free maritime air masses mainly from the North Atlantic up to about 50° W below the SAL. The North Atlantic westerlies, with their southern border occurring between 15 and 30° N (depending on the season, the longitude and the altitude), prevent the SAL from developing further northward. In addition, their southward shift with altitude gives SAL its characteristic oval shape in the northern part. The effective dry deposition velocity of dust particles is estimated to be 0.07 cm s−1 in winter, 0.14 cm s−1 in spring, 0.2 cm s−1 in summer and 0.11 cm s−1 in fall. Finally, the African Easterly Jet (AEJ) is observed to collocate with the maximum dust load of the SAL, and this might promote the differential advection for SAL parts, especially during summer.

scholarly journals Comparative Assessment and Future Prediction Using CMIP6 and CMIP5 for Annual Precipitation and Extreme Precipitation Simulation

2021 ◽  
Vol 9 ◽  
Author(s):  
Jingjing Li ◽  
Ran Huo ◽  
Hua Chen ◽  
Ying Zhao ◽  
Tianhui Zhao
Keyword(s):  
North America ◽  
South America ◽  
Amazon Basin ◽  
Coupled Model ◽  
Southern South America ◽  
Western Africa ◽  
Precipitation Simulation ◽  
The Future ◽  
Intercomparison Project ◽  
Changing Rate

This study assesses the improvement of the latest Coupled Model Intercomparison Project Phase 6 (CMIP6) over Coupled Model Intercomparison Project Phase 5 (CMIP5) for precipitation simulation. Precipitation simulations under different future climate scenarios are also compared in this work. The results show that: 1) CMIP6 has no overall advantage over CMIP5 in simulating total precipitation (PRCPTOT) and maximum consecutive dry days (CDD). The performance of CMIP6 increases or decreases regionally in PRCPTOT and consecutive dry days. But it is slightly worse than CMIP5 in simulating very wet days (R95pTOT). 2) Comparing the trend test results of CMIP5 and CMIP6 in the future, there are more areas with significant trend based on Mann–Kendall test in CMIP6 compared with that of CMIP5. The differences in PRCPTOT are mainly found in Amazon Basin and Western Africa. The differences between the R95pTOT trends mainly noticeable in South America and Western Africa, and the differences in CDD are mainly reflected in Central Asia, Sahara Desert and central South America. 3) In Southern South America and Western North America, the PRCPTOT changing rate of CMIP6 in the future under various scenarios is always greater than that of CMIP5; in Alaska, Western Africa, Southern Africa, the PRCPTOT changing rate of CMIP6 in the future under various scenarios is always less than that of CMIP5. In Southern South America, the R95pTOT changing rate of CMIP6 in the future under various scenarios is always greater than that of CMIP5; in Alaska, East Asia, North Asia, the R95pTOT changing rate of CMIP6 in the future under various scenarios is always less than that of CMIP5. In almost half of the regions, the CDD changing rate of CMIP6 is less than that of CMIP5 under all scenarios, namely Australia, Amazon Basin, Southern South America, Central America, Western North America, Central North America, Eastern North America, Central Asia, Tibet.

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