scholarly journals Approche multi-scalaire du démarrage de la saison des pluies au Sahel central et occidental : cohérence spatiale et prévisibilité (Multiscalar approach of the onset of rainy season in central and western Sahel : spatial coherence and predictability)

2010 ◽  
Vol 87 (2) ◽  
pp. 207-220
Author(s):  
Romain Marteau ◽  
Nathalie Philippon ◽  
Bernard Fontaine ◽  
Vincent Moron
Keyword(s):  
Rainy Season ◽  
Spatial Coherence ◽  
Western Sahel ◽  
Cohérence Spatiale

Resolving Contrasting Regional Rainfall Responses to El Niño over Tropical Africa

2016 ◽  
Vol 29 (4) ◽  
pp. 1461-1476 ◽  
Author(s):  
Pradipta Parhi ◽  
Alessandra Giannini ◽  
Pierre Gentine ◽  
Upmanu Lall
Keyword(s):  
Water Vapor ◽  
Indian Ocean ◽  
North Atlantic ◽  
El Niño ◽  
Rainy Season ◽  
El Nino ◽  
Sea Surface ◽  
Eastern Africa ◽  
Surface Warming ◽  
Western Sahel

Abstract The evolution of El Niño can be separated into two phases—namely, growth and mature—depending on whether the regional sea surface temperature has adjusted to the tropospheric warming in the remote tropics (tropical regions away from the central and eastern tropical Pacific Ocean). The western Sahel’s main rainy season (July–September) is shown to be affected by the growth phase of El Niño through (i) a lack of neighboring North Atlantic sea surface warming, (ii) an absence of an atmospheric column water vapor anomaly over the North Atlantic and western Sahel, and (iii) higher atmospheric vertical stability over the western Sahel, resulting in the suppression of mean seasonal rainfall as well as number of wet days. In contrast, the short rainy season (October–December) of tropical eastern Africa is impacted by the mature phase of El Niño through (i) neighboring Indian Ocean sea surface warming, (ii) positive column water vapor anomalies over the Indian Ocean and tropical eastern Africa, and (iii) higher atmospheric vertical instability over tropical eastern Africa, leading to an increase in the mean seasonal rainfall as well as in the number of wet days. While the modulation of the frequency of wet days and seasonal mean accumulation is statistically significant, daily rainfall intensity (for days with rainfall > 1 mm day−1), whether mean, median, or extreme, does not show a significant response in either region. Hence, the variability in seasonal mean rainfall that can be attributed to the El Niño–Southern Oscillation phenomenon in both regions is likely due to changes in the frequency of rainfall.

Nouvelle Méthode de Mesure de la Cohérence Spatiale en Lumière Pseudo-Thermique par Comptage des Photoélectrons

1971 ◽  
Vol 49 (14) ◽  
pp. 1940-1949 ◽  
Author(s):  
Claude Delisle ◽  
Jacques Bures
Keyword(s):  
Light Intensity ◽  
Probability Density ◽  
Spatial Coherence ◽  
Experimental Distribution ◽  
Observation Plane ◽  
Theoretical Probability ◽  
Exact Theory ◽  
Cohérence Spatiale

The light from a pseudothermal source is simultaneously detected in two points of the observation plane with a single photodetector. The degree of spatial coherence between the two points is determined from a comparison between one of the moments of the theoretical probability density P(i) of the light intensity at the photocathode and the corresponding moment of the experimental distribution of the photoelectrons. The moments of the probability density P(i) are derived from an exact theory which takes into account the degree of spatial coherence between the two points of the observation plane.

scholarly journals Extracting Subseasonal Scenarios: An Alternative Method to Analyze Seasonal Predictability of Regional-Scale Tropical Rainfall

2013 ◽  
Vol 26 (8) ◽  
pp. 2580-2600 ◽  
Author(s):  
Vincent Moron ◽  
Pierre Camberlin ◽  
Andrew W. Robertson
Keyword(s):  
Rainy Season ◽  
Early Stage ◽  
Regional Scale ◽  
Spatial Coherence ◽  
Daily Rainfall ◽  
Seasonal Prediction ◽  
East African ◽  
Seasonal Predictability ◽  
Potential Predictability ◽  
Noise Component

Abstract Current seasonal prediction of rainfall typically focuses on 3-month rainfall totals at regional scale. This temporal summation reduces the noise related to smaller-scale weather variability but also implicitly emphasizes the peak of the climatological seasonal cycle of rainfall. This approach may hide potentially predictable signals when rainfall is lower: for example, near the onset or cessation of the rainy season. The authors illustrate such a case for the East African long rains (March–May) on a network of 36 stations in Kenya and north Tanzania from 1961 to 2001. Spatial coherence and potential predictability of seasonal rainfall anomalies associated with tropical sea surface temperature (SST) anomalies clearly peak during the early stage of the rainy season (in March), while the largest rainfall (in April and May) is far less spatially coherent; the latter is shown to contain a large noise component at the station scale that characterizes interannual variability of the March–May seasonal total amounts. Combining the empirical orthogonal function of both interannual and subseasonal variations with a fuzzy k-means clustering is shown to capture the most spatially coherent subseasonal “scenarios” that tend to filter out the noisier variations of the rainfall field and emphasize the most consistent signals in both time and space. This approach is shown to provide insight into the seasonal predictability of long dry spells and heavy daily rainfall events at local scale and their subseasonal modulation.

Quanitative aspects of electron diffraction using electron holography

1995 ◽  
Vol 53 ◽  
pp. 616-617
Author(s):  
E. Völkl ◽  
L.F. Allard ◽  
B. Frost ◽  
T.A. Nolan
Keyword(s):  
Electron Beam ◽  
Electron Diffraction ◽  
Software Package ◽  
Spatial Coherence ◽  
Electron Holography ◽  
Image Intensity ◽  
Interference Fringes ◽  
Complex Image ◽  
The Difference ◽  
Recorded Image

Off-axis electron holography has the well known ability to preserve the complex image wave within the final, recorded image. This final image described by I(x,y) = I(r) contains contributions from the image intensity of the elastically scattered electrons IeI (r) = |A(r) exp (iΦ(r)) |, the contributions from the inelastically scattered electrons IineI (r), and the complex image wave Ψ = A(r) exp(iΦ(r)) as:(1) I(r) = IeI (r) + Iinel (r) + μ A(r) cos(2π Δk r + Φ(r))where the constant μ describes the contrast of the interference fringes which are related to the spatial coherence of the electron beam, and Φk is the resulting vector of the difference of the wavefront vectors of the two overlaping beams. Using a software package like HoloWorks, the complex image wave Ψ can be extracted.

Extending the processing of cocoa beans into the rainy season and increasing production by application of newly developed drying methods

2017 ◽  
Author(s):  
Global Cocoa Farmers and Processing Firms and Processing Firms ◽  
IQUAIBOM AKPAN MEX (MEXICATEL SERVICES LIMITED)
Keyword(s):  
Rainy Season ◽  
Drying Methods ◽  
Cocoa Beans

EPIDEMIOLOGY, ECOLOGY AND PREVALENCE OF SOIL TRANSMITTED HELMINTHS FROM KOSHI REGION OF NORTH BIHAR.

2018 ◽  
Vol 24 (1) ◽  
Author(s):  
LAKSHMI CHOUDHARY ◽  
PRABHAWATI PRABHAWATI
Keyword(s):  
Relative Humidity ◽  
Ascaris Lumbricoides ◽  
Rainy Season ◽  
Climatic Factors ◽  
Trichuris Trichiura ◽  
Hookworm Infection ◽  
Soil Transmitted Helminths ◽  
High Incidence ◽  
Apparently Healthy

Prevalence of soil transmitted helminthes infections in apparently healthy school going children and other 528 people of different districts of Koshi regions of North Bihar were evaluated. Over all incidences of STHs infection was 39.39% during study. High incidence of STH was seen in the rainy season i.e., in the month of July and August, September, significantly higher (P<0.05) .The incidence of Ascaris lumbricoides was highest in the month of August (18.64%). The month of September was 15.25% followed by that of July (14.4%) and October with 10.16%. Also the incidence of hookworm registered the highest incidence in the month of June (19.27%) and lowest in the month of December (4.82%) during the study period. However prevalence of Trichuris trichiura was negligible and it was almost nil in the most of the months but was highest in month of September with 28.57% and lowest in October with 14.00% The climatic factors are responsible for soil transmitted helminthes which are temperature, rainfall and relative humidity. Ascariasis, Trichuriasis and Ancyclostomiasis (Hookworm infection) are found to be endemic in this region.

STUDY ON DIVERSITY AND DISTRIBUTION OF ANTS (HYMENOPTERA: FORMICIDAE) IN URBAN AND PERIURBAN AREAS OF AURANGABAD CITY, MAHARASHTRA, INDIA

2017 ◽  
Vol 23 (2) ◽  
Author(s):  
S. D. CHATE ◽  
R. J. CHAVAN
Keyword(s):  
Rainy Season ◽  
Winter Season ◽  
Seasonal Abundance ◽  
Urban Region ◽  
Ant Community ◽  
Community Variation

The present study deals with the ant community variation in and around Aurangabad city. During the study total 16 species of ants belonging to twelve genera and four subfamilies were reported in eight habitat from urban and periurban regions. Abundance of ants was more in peri-urban region as compared to urban region. Subfamily myrmicinae was more dominant as compared to other subfamilies. Seasonal abundance of ants was seen to be more in winter season and less in rainy season.

Incubation Temperature Influences the Duration of Egg Hatching and Early Development in the Boreal Digging Frog, Kaloula Borealis

2020 ◽  
Vol 3 (1) ◽  
pp. ACCEPTED
Author(s):  
Rho-Jeong Rae
Keyword(s):  
Water Temperature ◽  
Early Life ◽  
Rainy Season ◽  
Incubation Temperature ◽  
Life Stages ◽  
Early Life Stages ◽  
Egg Hatching ◽  
Significant Difference ◽  
The Mean ◽  
Hatching Rates

This study investigated the boreal digging frog, Kaloula borealis, to determine the egg hatching period and whether the hatching period is affected by incubation temperature. The results of this study showed that all the eggs hatched within 48 h after spawning, with 28.1% (±10.8, n=52) hatching within 24 h and 99.9% (±0.23, n=49) within 48 h after spawning. A significant difference was noted in the mean hatching proportion of tadpoles at different water temperatures. The mean hatching rates between 15 and 24 h after spawning was higher at a water temperature of 21.1 (±0.2) °C than at 24.1 (±0.2) °C. These results suggest that incubation temperature affected the early life stages of the boreal digging frog, since they spawn in ponds or puddles that form during the rainy season.

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