scholarly journals Variability and the Severity of the “Little Dry Season” in Southwestern Nigeria

2006 ◽  
Vol 19 (3) ◽  
pp. 483-493 ◽  
Author(s):  
James O. Adejuwon ◽  
Theophilus O. Odekunle
Keyword(s):  
Interannual Variability ◽  
Agricultural Practices ◽  
Daily Rainfall ◽  
Walker Circulation ◽  
Dry Season ◽  
Total Rainfall ◽  
Southwestern Nigeria ◽  
The Mean ◽  
Period Of Occurrence ◽  
River Niger

Abstract The Little Dry Season (LDS) of West Africa is manifested as a decline in both the frequency and amount of daily rainfall for a number of weeks halfway through the rainy season. The mean or climatological LDS is derived from the slope of the cumulative percentage graph of 5-day mean rainfall (daily rainfall data between 1961 and 2000). LDS variability analysis was carried out using the concept of relative variability. The results obtained showed that LDS is observed from mid-July to mid-September along the coast. Northward and eastward the period of occurrence decreases. In general, the phenomenon is not observed north of the eastward-flowing or east of the southward-flowing River Niger. The results also show considerable interannual variability. Variability was highest along the southwestern coast and declined inland northward and eastward. Variability was highest with respect to total rainfall, followed by length and number of rain days. There are indications that for most years the LDS was only relatively dry while in certain years it represented a period of drought. The occurrence of the LDS in space and time is explained by the movements of the intertropical discontinuity and its associated zone of rainfall. Interannual variability in occurrence and severity are determined by the Walker Circulation phenomenon. Variability in the severity of the LDS has mixed implications for agricultural practices.

scholarly journals FACTORS AFFECTING LIVEWEIGHT OF GOAT AND SHEEP IN TWO LOCATION WITHIN OGUN STATE.

2021 ◽  
Vol 23 (1) ◽  
pp. 12-15
Author(s):  
C. O. N. IKEOBI ◽  
O. A. FALETI
Keyword(s):  
Dry Season ◽  
West African ◽  
Wet Season ◽  
The West ◽  
Southwestern Nigeria ◽  
Factors Affecting ◽  
West African Dwarf ◽  
Ogun State ◽  
West African Dwarf Goat ◽  
The Mean

A study was conducted over two years  With the to determine the changes in the liveweight of Yankasa sheep and Maradi goat in goats and sheep in two locations in Ogun State, South-Western Nigeria Factors found to be important included breed of goat, season, location, and sex of the animal. The Maradi goat had a greater variation in its liveweight than the West African' dwarf goat. The mean weekly gain in the liveweight of goats was 0.18±02 dry season and 0.26±0.05 kg in the wet season. Liveweight changes were greater in yearling Yankasa sheep reared in this part of the Southwestern Nigeria than in older ones; these differences were significantly greater in the dry than in the wet season.

scholarly journals Insect Pest Profile of Leaf Amaranth (Amaranthus hybridus L) and Prevention Herbivory Using Oil-Based Extracts of Alium sativum L, Xylopia aethiopica Dunal and Eucalyptus globolus L

2019 ◽  
pp. 1-9
Author(s):  
Borisade, O. A. ◽  
Awodele, S. O. ◽  
Uwaidem, Y. I.
Keyword(s):  
Vegetable Oil ◽  
Insect Pest ◽  
Dry Season ◽  
Phytophagous Insects ◽  
Southwestern Nigeria ◽  
Amaranthus Hybridus ◽  
Significant Damage ◽  
Significant Difference ◽  
The Mean ◽  
Xylopia Aethiopica

Pest profile of Amaranthus hybridus was recorded in a single organic agro-ecosystem in Southwestern Nigeria between November-December in 2016 and January-February 2017, during the dry season. Activities of different pests were monitored to identify those responsible for the most significant damage. Vegetable oil-based extracts of Alium sativum, Xylopia aethiopica and Eucalyptus globolus were prepared and applied on A. hybridus as protectants against herbivory by phytophagous insects and damage to foliage was assessed. Thereafter, the extracts were rated based on the mean percentage damage (MPD) recorded in different plots in relation to the treatments. A total of nine pests were recorded from three insect Orders namely, Orthoptera (62.5%), Coleoptera (12.5%) and Lepidoptera (25%) and they were grouped into Major, Minor or Occasional pests based on their activities. Two lepidopterans, Spoladea recurvalis and Psara basalis (Family: Crambidae) were responsible for the most significant damage. All the extracts reduced damage with a statistically significant difference (P<0.05) compared with the control. The MPD in X. aethiopica-, A. sativum- and E. globolus-treated plots and the control plots were 10.9%, 8%, 14% and 31.2% respectively when the amaranth was due for harvest in the first trial. The MPD to the amaranth in the treated plots during the second trial was between 13.6% and 16.3% when the harvest was due while the MPD in the control was 54.9%. The performances of E. globolus and X. aethiopica were comparable and they were relatively more effective in protecting A. hybridus against phytophagous pest attacks.

scholarly journals Weather Types and Rainfall over Senegal. Part II: Downscaling of GCM Simulations

2008 ◽  
Vol 21 (2) ◽  
pp. 288-307 ◽  
Author(s):  
Vincent Moron ◽  
Andrew W. Robertson ◽  
M. Neil Ward ◽  
Ousmane Ndiaye
Keyword(s):  
Interannual Variability ◽  
Nearest Neighbor ◽  
Daily Rainfall ◽  
K Nearest Neighbor ◽  
Wind Fields ◽  
Weather Types ◽  
Local Scaling ◽  
Rainfall Frequency ◽  
Dry Spells ◽  
The Mean

Abstract Four methods of downscaling daily rainfall sequences from general circulation model (GCM) simulations are intercompared over Senegal, using a 13-station network of daily observations during July–September 1961–98. The local scaling method calibrates raw GCM daily rainfall at the closest grid point to a given station so that the climatological distribution of rainfall matches the observed one. The k-nearest neighbor and weather classification schemes resample historical station rainfall observations according to the similarity between the daily wind fields from an ensemble of GCM simulations and a historical library of reanalysis [from 40-yr ECMWF Re-Analysis (ERA-40)] daily wind fields. The nonhomogenous hidden Markov model uses a small set of hidden states to describe the relationship between daily station rainfall observations and low-pass-filtered simulated winds to simulate stochastic sequences of daily rainfall. The four methods are assessed in terms of seasonal statistics of daily rainfall, including seasonal amount, rainfall frequency, and the mean length of wet and dry spells. Verification measures used are mean bias error, interannual anomaly correlation, root-mean-square error, and ranked probability skill score. The k-nearest neighbor and weather-type classification are shown to perform similarly well in reproducing the mean seasonal cycle, interannual variability of seasonal amount, daily rainfall frequency, as well as the mean length of dry and wet spells, and generally slightly better than the nonhomogeneous hidden Markov model. All three methods are shown to outperform the simple local scaling method. This is due to (i) the ability of the GCM to reproduce remarkably well the mean seasonal cycle and the transitions between weather types defined from reanalysis and (ii) the GCM’s moderate-to-strong skill in reproducing the interannual variability of the frequency occurrence of the weather types that strongly influence the interannual variability of rainfall in Senegal. In contrast, the local scaling exaggerates the length of wet and dry spells and reproduces less accurately the interannual variability of the seasonal-averaged amounts, occurrences, and dry/wet spells. This failure is attributed primarily to systematic errors in the GCM’s precipitation simulation.

scholarly journals Seasonal Climate Impacts on Vocal Activity in Two Neotropical Nonpasserines

Diversity ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 319
Author(s):  
Cristian Pérez-Granados ◽  
Karl-L. Schuchmann
Keyword(s):  
Air Temperature ◽  
Daily Rainfall ◽  
Climatic Conditions ◽  
Dry Season ◽  
Climate Impacts ◽  
Calling Behavior ◽  
Wet Season ◽  
Focal Species ◽  
Calling Activity ◽  
Vocal Activity

Climatic conditions represent one of the main constraints that influence avian calling behavior. Here, we monitored the daily calling activity of the Undulated Tinamou (Crypturellus undulatus) and the Chaco Chachalaca (Ortalis canicollis) during the dry and wet seasons in the Brazilian Pantanal. We aimed to assess the effects of climate predictors on the vocal activity of these focal species and evaluate whether these effects may vary among seasons. Air temperature was positively associated with the daily calling activity of both species during the dry season. However, the vocal activity of both species was unrelated to air temperature during the wet season, when higher temperatures occur. Daily rainfall was positively related to the daily calling activity of both species during the dry season, when rainfall events are scarce and seem to act as a trigger for breeding phenology of the focal species. Nonetheless, air temperature was negatively associated with the daily calling activity of the Undulated Tinamou during the wet season, when rainfall was abundant. This study improves our understanding of the vocal behavior of tropical birds and their relationships with climate, but further research is needed to elucidate the mechanisms behind the associations found in our study.

scholarly journals Directional Distance Function Technical Efficiency of Chili Production in Thailand

2021 ◽  
Vol 13 (2) ◽  
pp. 741
Author(s):  
Wirat Krasachat ◽  
Suthathip Yaisawarng
Keyword(s):  
Distance Function ◽  
Rainy Season ◽  
Sample Selection ◽  
Agricultural Practices ◽  
Directional Distance Function ◽  
Dry Season ◽  
Small Samples ◽  
Function Technique ◽  
Security Problem ◽  
Gap Technology

To overcome the challenging food safety and security problem, in 2003, the Thai government initiated ‘Good Agricultural Practices’ (GAP) technology. This paper used a sample of 107 small chili farms from the Chiyaphoom province for the 2012 crop year, and data envelopment analysis (DEA) meta-frontier directional distance function technique to answer two questions: (1) Are GAP-adopting farms, on average, more efficient than conventional farms? (2) Does access to GAP technology affect farmers’ decisions to adopt GAP technology? We also developed an ‘indirect’ approach to reduce the potential sample selection bias for small samples. For the dry-season subsample, GAP farms were more technically efficient when compared with non-GAP farms. These dry-season non-GAP farms may not adopt the GAP method because they have limited access to GAP technology. For the rainy-season subsample, on average, GAP farms were more efficient than non-GAP farms at the 5% level. Access to the GAP technology is not a possible reason for non-GAP rainy season farms to not adopt the GAP technology. To enable sustainable development, government agencies and nongovernmental organizations (NGOs) must develop and implement appropriate educational and training workshops to promote and assist GAP technology adoption for chili farms in Thailand.

scholarly journals Cambial Activity and Phenology in Three Understory Species along an Altitude Gradient in Mexico

Forests ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 506
Author(s):  
Mayte S. Jiménez-Noriega ◽  
Lauro López-Mata ◽  
Teresa Terrazas
Keyword(s):  
Soil Temperature ◽  
Sierra Nevada ◽  
Cambial Activity ◽  
Life Forms ◽  
Dry Season ◽  
Vascular Cambium ◽  
Phenological Stages ◽  
Altitude Gradient ◽  
The Mean ◽  
Trees And Shrubs

The aims of this study were to evaluate the cambial activity and phenology of three species with different life forms (Alchemilla procumbens, Acaena elongata and Ribes ciliatum) along an altitudinal gradient and to establish which environmental variables (light, soil humidity and temperature) had the greatest influence on cambial activity and phenological stages. Over two years, data on phenology, growth and cambium were gathered every four weeks in three to six sites per species in Sierra Nevada, Mexico. The results showed that Ribes is the only species that terminates cambial activity with leaves senescence and is influenced by the minimum soil temperature. The light environment influenced the vegetative stages in Alchemilla (cryptophyte), while in Acaena (hemicryptophyte), the mean soil temperature explained the findings related to leaf area during the dry season and growth along the gradient. In the three species, the reproductive phase dominated for a longer period at higher elevations, especially in Alchemilla. Only Ribes, the phanerophyte, showed a similar cambial activity to other trees and shrubs. Although cambium reactivates during the dry season, no xylogenesis occurs. The three species varied during the time in which vascular cambium was active, and this was dependent on the altitude. Specifically, the variation was more rhythmic in Ribes and switched on and off in Alchemilla. It is likely that, depending on the life form, vascular cambium may be more or less susceptible to one or more climate factors.

Implications of body condition and seasonality on morphological and functional parameters of testes of Myotis nigricans (Chiroptera: Vespertilionidae)

2018 ◽  
Vol 30 (7) ◽  
pp. 1029
Author(s):  
Marcelo Ferreira ◽  
Aline Soldati ◽  
Sirlene S. S. Rodrigues ◽  
Laércio dos Anjos Benjamin
Keyword(s):  
Light Microscopy ◽  
Body Condition ◽  
Environmental Variables ◽  
Reproductive Strategies ◽  
Leydig Cells ◽  
Dry Season ◽  
The Body ◽  
Reproductive Capacity ◽  
Seminiferous Tubules ◽  
The Mean

The insectivorous bat Myotis nigricans is widely distributed throughout the Neotropics, including Brazil, and has a reproductive biology that is affected by climate and food availability. To evaluate the reproductive capacity of this species, morphofunctional parameters of the testes were correlated with environmental variables and the body condition of individuals captured. After bats had been killed, their testes were removed, fixed in Karnovsky’s fluid for 24 h and embedded in resin for evaluation by light microscopy. The mean annual tubulosomatic index (0.58%) and the percentage of seminiferous tubules in the testes (88.96%) were the highest ever recorded for the Order Chiroptera. The percentage of Leydig cells and volume of the cytoplasm of Leydig cells were higher in the rainy than dry season (80.62 ± 3.19% and 573.57 ± 166.95 μm, respectively; mean ± s.d.). Conversely, the percentage of nuclei of the Leydig cells in the dry season (26.17 ± 3.70%; mean ± s.d.) and the total number of Leydig cells (6.38 ± 1.84 × 109; mean ± s.d.) were higher in the dry season. The results of the present study could help in future conservation of these bats because they provide a better understanding of the bats’ reproductive strategies and how the species can adapt to changes.

Comparison of Emission Levels of Motor Cars, Motorcycles, and Tricycles Using Petrol Engines in Southwestern Nigeria

2021 ◽  
Vol 900 ◽  
pp. 183-187
Author(s):  
Odunlami Olayemi Abosede ◽  
Akeredolu Funso Alaba
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Carbon Dioxide Emissions ◽  
Mean Value ◽  
Southwestern Nigeria ◽  
Mean Values ◽  
Mobile Sources ◽  
Southwest Nigeria ◽  
The Mean ◽  
European Standards

The emissions of carbon monoxide, carbon dioxide, and hydrocarbon from four stroke-powered motorcars and two stroke-powered motorcycles and tricycles in Southwest Nigeria were examined using an automotive 4-gas analyer. Results show that tricycles produced more hydrocarbon and carbon monoxide emissions than motorcycles, while motorcycles emitted more of these pollutants than the gasoline fueled motor cars. (The gasoline fueled motorcars produced lowest hydrocarbon and carbon monoxide while the tricycles produced the highest hydrocarbon and carbon monoxide emissions). On the contrary, motor cars had the highest mean value of carbon dioxide followed by the motorcycles, while tricycles had the least. This could be attributed to the presence of the catalytic converters in some of the motor cars oxidizing carbon monoxide to carbon dioxide. The mean values of hydrocarbon, carbon monoxide and carbon dioxide emissions from motorcars are 630ppm, 10200ppm and 59900ppm. This is much higher than the NESREA (National Environmental standards and Regulations Enforcement Agency) standards as well as Euro II and Euro III (European standards) for vehicular emission. The mean values for hydrocarbon, carbon monoxide and carbon dioxide emissions from motorcycles and tricycles are (2150ppm, 21530ppm and 31200ppm) and (2820ppm, 24880ppm and 38710ppm) respectively. These results do not comply with Nigeria and European emission standards for hydrocarbon, and carbon monoxide. Tricycles and motorcycles account for higher concentrations of hydrocarbon and carbon monoxide pollutants from mobile sources, while they emit carbon dioxide minimally.

Interdecadal changes in the interannual variability of the summer temperature over Northeast Asia

2021 ◽  
pp. 1-50
Author(s):  
Ruidan Chen ◽  
Zhiping Wen ◽  
Riyu Lu ◽  
Wenjun Liu
Keyword(s):  
Interannual Variability ◽  
Northeast Asia ◽  
Tropical Indian Ocean ◽  
Summer Temperature ◽  
Atmospheric Variability ◽  
The Pacific ◽  
The Mean ◽  
Southeastern Tropical Indian Ocean ◽  
Interdecadal Changes ◽  
Mean State

AbstractThis study reveals the interdecadal changes in the interannual variability of the summer temperature over Northeast Asia (NEA), which presents an enhancement around the early 1990s and a reduction after the mid-2000s. The stronger NEA temperature variability after the early 1990s is favored by the enhanced influence of the Pacific–Japan (PJ) teleconnection, which is remotely modulated by the southeastern tropical Indian Ocean (SETIO). After the early 1990s, the mean state over the SETIO presents relatively warmer SST and ascending motion, favoring a good relationship between the local SST and convection. Therefore, the SETIO SST could prominently influence the local convection and subsequently modulate the convection over the western North Pacific (WNP) via a cross-equatorial overturning circulation. The abnormal convection over the WNP further triggers the PJ teleconnection to influence NEA. However, these ocean–atmosphere processes disappear before the early 1990s. In this period, the mean state over the SETIO features relatively colder SST and subsiding motion, accompanied by a poor relationship between the local SST and convection. Therefore, the variability of convection over the SETIO is weak, thus the atmospheric variability over the WNP is also weakened and the PJ teleconnection presents a different distribution that could not influence NEA. The reduced variability of NEA temperature after the mid-2000s is related to the feeble influence of the PJ teleconnection and the reduced variability of the SETIO SST, which is modulated by the SST over the tropical central–eastern Pacific during the preceding winter to spring.

scholarly journals Impact of Resolution on the Tropical Pacific Circulation in a Matrix of Coupled Models

2009 ◽  
Vol 22 (10) ◽  
pp. 2541-2556 ◽  
Author(s):  
Malcolm J. Roberts ◽  
A. Clayton ◽  
M.-E. Demory ◽  
J. Donners ◽  
P. L. Vidale ◽  
...  
Keyword(s):  
Coupled Model ◽  
Walker Circulation ◽  
Ocean Model ◽  
Tropical Pacific ◽  
Coupled Models ◽  
Model Stability ◽  
The Mean ◽  
The Impact ◽  
Mean State ◽  
The Tropical Pacific

Abstract Results are presented from a matrix of coupled model integrations, using atmosphere resolutions of 135 and 90 km, and ocean resolutions of 1° and 1/3°, to study the impact of resolution on simulated climate. The mean state of the tropical Pacific is found to be improved in the models with a higher ocean resolution. Such an improved mean state arises from the development of tropical instability waves, which are poorly resolved at low resolution; these waves reduce the equatorial cold tongue bias. The improved ocean state also allows for a better simulation of the atmospheric Walker circulation. Several sensitivity studies have been performed to further understand the processes involved in the different component models. Significantly decreasing the horizontal momentum dissipation in the coupled model with the lower-resolution ocean has benefits for the mean tropical Pacific climate, but decreases model stability. Increasing the momentum dissipation in the coupled model with the higher-resolution ocean degrades the simulation toward that of the lower-resolution ocean. These results suggest that enhanced ocean model resolution can have important benefits for the climatology of both the atmosphere and ocean components of the coupled model, and that some of these benefits may be achievable at lower ocean resolution, if the model formulation allows.

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