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Two-Stream Approximation to the Radiative Transfer Equation:A New Improvement and Comparative Accuracy with Existing Methods

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Advances in Atmospheric Sciences 2024年第2期41卷 278-292页

作者： f.momo temgoua L.Akana NGUIMDO DNJOMO Environmental Energy Technologies Laboratory(EETL) Faculty of SciencesUniversity of YaoundéPO Box 812 YaoundéCameroon Department of Electrical and Electronic Engineering Faculty of Engineering and TechnologyUniversity of BueaPO Box 63 BueaCameroon

Mathematical modeling of the interaction between solar radiation and the Earth's atmosphere is formalized by the radiative transfer equation(RTE), whose resolution calls for two-stream approximations among other methods. This paper proposes a new two-stream approximation of the RTE with the development of the phase function and the intensity into a third-order series of Legendre polynomials. This new approach, which adds one more term in the expression of the intensity and the phase function, allows in the conditions of a plane parallel atmosphere a new mathematical formulation of γparameters. It is then compared to the Eddington, Hemispheric Constant, Quadrature, Combined Delta function and Modified Eddington, and second-order approximation methods with reference to the Discrete Ordinate(Disort) method(δ –128 streams), considered as the most precise. This work also determines the conversion function of the proposed New Method using the fundamental definition of two-stream approximation(f-TSA) developed in a previous work. Notably,New Method has generally better precision compared to the second-order approximation and Hemispheric Constant methods. Compared to the Quadrature and Eddington methods, New Method shows very good precision for wide domains of the zenith angle μ 0, but tends to deviate from the Disort method with the zenith angle, especially for high values of optical thickness. In spite of this divergence in reflectance for high values of optical thickness, very strong correlation with the Disort method(R ≈ 1) was obtained for most cases of optical thickness in this study. An analysis of the Legendre polynomial series for simple functions shows that the high precision is due to the fact that the approximated functions ameliorate the accuracy when the order of approximation increases, although it has been proven that there is a limit order depending on the function from which the precision is lost. This observation indicates that increasing the order of app

关键词： Radiative Transfer Equation two-stream method Legendre polynomial optical thickness moments of specific intensity conversion function transmittance reflectance

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Typology and Agroecology of Agroecosystems in Vegetation Dynamics in the Ecotones of the Mbam and Inoubou

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Open Journal of forestry 2024年第1期14卷 42-66页

作者： Alex Bruno Dong Etchike Lucie félicité temgoua Bertine Tiokeng Marie Caroline momo Solefack Martin Benoit Ngassoum Pierre Marie Mapongmetsem Laboratory of Applied Botany Faculty of Sciences of the University of Dschang Dschang Cameroon Department of forestry Faculty of Agronomy and Agricultural Sciences University of Dschang Dschang Cameroon National School of Agro-Industrial Sciences of the University of Ngaoundéré Ngaoundéré Cameroon Laboratory of Biodiversity and Sustainable Development of the University of Ngaoundéré Ngaoundéré Cameroon

Agroforestry systems strongly characterize the Cameroonian agrarian landscape. Agroforests are among those structuring the ecotones of Mbam and Inoubou in the Central Cameroon region. Numerous works on agroecosystems of Central and South Cameroon, few have come out contribution of the structure of these traditional systems in the dynamics of the vegetation of these forest-savannah ecotones. The present contribution has the overall objective of demonstrating the structural efficiency of agroforests the dynamics of ecotone vegetation, but also in the conservation of biodiversity. To do this, a participatory analysis was carried out with 56 farmers distributed in the five villages of Makénéné. Botanical inventories supplemented socio-economic household surveys. The data collected was subjected to various analyzes (univariate test, analysis of variance, multivariate test, PCA, CAH). The results reveal that 55.2% of agroforests are less than 15 years old and those with an area greater than 1500 m2 predominate (33%). They are mainly young with generally small surface areas. The horizontal structure reveals that the largest diameter classes are those of [20 - 30 cm[ and [10 - 20 cm[ with a very low rate of basal area. Agroforests with trees over 10 m high are dominant in five villages of Makénéné. Two types of structural profiles characterize the agroforestry flora of the area, namely intensive pluristratified home gardens on savannah and intensive pluristratified agroforests under forest-savannah transition vegetation. Principal Component Analysis (PCA) and Ascending Hierarchical Clustering (HAC) show three Agroforest Clusters each. The PCA distribution reveals that woody biomass (Y) is strongly correlated with tree diameter (DBH) and significantly with height (Cluster 2). The age (AAG) (Cluster 1) of these agroforests, on the other hand, remains independent of the density (DST) of these trees (Cluster 3). The agroforests in the Nyokon, Carrière and Mocksud vil

关键词： Agroforests Agroecosystem Center Cameroon Dynamics Agroecology Typology

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Effect of Different Rates and Mixtures of Solid Household Waste and faecal Sludge-Based Composts on Soil fertility and Productivity of Sunflower (Helianthus annuus L.) in Dschang, West Cameroon

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Open Journal of Soil Science 2024年第7期14卷 448-470页

作者： Romary Ngnipa Tchinda Rodrigue Emmanuel Kenne Primus Azinwi Tamfuh Jovanie Gladys Kenfack Doris temgoua Zombou Désiré Évariste Moundjeu Tsafack Richard Tanwi Ghogomu Emile temgoua Dieudonné Bitom Oyono Department of Environmental Sciences of the Higher Institute of Agriculture Wood Water and the Environment of the University of Bertoua Blabo Cameroon Department of Soil Science Soil Analysis and Environmental Chemistry Research Unit Faculty of Agronomy and Agricultural Sciences University of Dschang Dschang Cameroon Department of Mining and Mineral Engineering National Higher Polytechnic Institute University of Bamenda Bambili Cameroon Department of Animal Biology Faculty of Sciences University of Dschang Dschang Cameroon Department of Earth Sciences University of Yaounde 1 Yaounde Cameroon

The unbalanced and inadequate use of fertilizers is one of the causes of soil degradation. Combined with the ever-increasing population, it is necessary to find sustainable agricultural production alternatives. The present work aims to determine the effect of different rates and mixtutes of organic amendments on soil fertility and the performance of Sunflower (Helianthus annuus L.). In the field, treatments consisted of solid household waste and faecal sludge in the ratios of 3/5 (V1), and a mixture of faecal sludge and household waste in the ratio of 3/5 with 900 worms (V2). At the end of the composting process, V1, V2 composts and the poultry manure (PM) were applied at rates of 4, 5 and 6 t∙ha−1 in a randomized complete block design with three replications. Soil samples were collected before and after the experiment and analyzed. The main results revealed that at the end of the composting process, there was a progressive improvement in the physico-chemical properties of V1 and V2 composts. In particular, the C/N ratio, phosphorus (P) and total nitrogen (TN) initially at 16.49 ± 0.42 (V1, V2), 21.06 ± 0.07 mg∙kg−1 (V1, V2), 0.76% ± 0.08% (V1, V2) respectively, increased after 60 days to 12.40 ± 0.41 (V1), 9.74 ± 0.28 (V2) for C/N, 21.94 ± 0.63 mg∙kg−1 (V1) and 22.04 ± 0.04 mg∙kg−1 (V2) for P, 0.96% ± 0.0% (V1) and 1.22 ± 0.04 (V2) for TN. The application of 6 t∙ha−1of PM had the greatest influence on the diameter and weight of the flower heads (27.16 ± 4.01 t∙ha−1 and 230.83 ± 2.64 t∙ha−1), while 4 t∙ha−1 of V2 gave the tallest sunflower plants (110.07 ± 73.28 cm) as well as the diameter at the crown (19.30 ± 9.07 cm). However, CEC was most influenced by 4 t∙ha−1 of V1, while 4 t∙ha−1 of PM had the greatest effect on organic carbon and phosphorus. However, 5 t∙ha−1 of PM showed the highest sunflower production and yield (1.67 ± 0.21 t∙ha−1). The combination with 900 earthworms is recommended for composting and 5 t∙ha−1 of PM is recommended to obtain a better sunfl

关键词： Sunflower faecal Sludge Household Waste Compost Soil fertility

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Soil Organic Carbon and Nitrogen Dynamics in Arabica Coffee Agroforestry Systems in the Noun Division, West Cameroon

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Open Journal of forestry 2023年第3期13卷 262-277页

作者： Abdel Malik Atoupka Emile temgoua Lucie félicité temgoua Jean Baurel Atchombou Steve Tassiamba faculty of Agronomy and Agricultural Sciences University of Dschang Dschang Cameroon

Agroforestry systems (AfSs) offer viable solutions to climate change because of the below-ground biomass (BGB) that is maintained by the soil. Therefore, spatially explicit estimation of their BGB is crucial to account for emission reduction efforts. A study to assess soil organic carbon (SOC) and nitrogen dynamics in Arabica coffee agroforests was conducted in two subdivisions (foumbot and Kouoptamo) of the Noun Division in western Cameroon. The methodological approach involved the collection of 150 soil samples taken at different depths: 0 - 10, 10 - 20 and 20 - 30 cm. Depending on the depth, the SOC stock is 27.93 ± 1.13 tC/ha at 10 cm depth, 22.37 ± 1.47 tC/ha at 20 cm and 20.79 ± 0.31 tC/ha at 30 cm. According to the age classes of the Arabica coffee systems (ACA), the C/N ratio in our study area averaged 26.94 ± 13.60 for the (5 - 20) year old systems in foumbot and 60.64 ± 48.80 for the (20 - 35) year old systems in Kouoptamo. Depending on the depth, at 10 cm this ratio is higher in Kouoptamo than in foumbot with a maximum value of 57 and 38 respectively for the two subdivisions. In view of the results obtained, it would be important to analyse the types of microorganisms responsible for the decomposition of organic matter which is linked to soil organic carbon.

关键词： Agroforestry Systems Coffee Trees Soil Organic Carbon Noun Division West Cameroon

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Hydro-geochemistry of groundwater and surface water in Dschang town(West Cameroon):Alkali and alkaline-earth elements ascertain lithological and anthropogenic constraints

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Journal of Groundwater Science and Engineering 2021年第3期9卷 212-224页

作者： Yemeli Elida Joelle temgoua Emile Kengni Lucas Ambrosi Jean-Paul momo-nouazi Mathieu Silatsa-Tedou francis Brice Wamba franck Robean Tchakam-Kamtchueng Brice University of Dschang Department of Earth SciencesDschangCameroon. University of Dschang Faculty of Agronomy and Agricultural SciencesDschangCameroon. Aix Marseille University CNRSIRDINRAECollege de FranceCEREGEAix En ProvenceFrance. Institute of Geological and Mining Research YaoundeCameroon.

The study aims to identify a suitable site for open and bore well in a farmhouseusing ground magnetic survey in south *** also aims to define depth to granitoid and structural elements which traverse the selected *** data(n=84)measured,processed and interpreted as qualitative and *** results of total magnetic intensities indicate that the area is composed of linear magnetic lows trending NE-SW direction and circular to semi-circular causative *** magnetic values ranged from-137 nT to 2345 nT with a mean of 465 *** to equator shows significant shifting of causative bodies in the southern and northern *** signal map shows exact boundary of granitic *** directional filter has brought out structural element trending NE-SW *** of individual profile brought to light structurally weak zone between 90 m and 100 m in all the profile *** decrease of magnetic values from 2042 nT to 126 nT noticed in profile line 6 between 20 m and 30 m indicates fault *** breaks obtained from these maps were visualized,interpreted and identified two suitable sites for open and bore *** averaged power spectrum estimates depth of shallow and deep sources in 5 m and 50 m,*** method has also been applied to estimate depth of granitoid and structural elements using structural indexes 0,1,2,and 3 and found depth ranges from90 *** indicates magnetic method is one of the geophysical methods suitable for groundwater exploration and site selection for open and borewells.

关键词： Alkali/alkaline-earth elements Groundwater and surface water Geochemical anomaly Anthropogenic impact Dschang-Cameroon

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Evaluating the Role of Governance in the Management of Prunus africana (Hook.f.) Kalkman in the Adamawa Region of Cameroon

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Open Journal of forestry 2022年第4期12卷 408-431页

作者： Steve Nanfack Tassiamba Jean Lagarde Betti Lucie félicité temgoua Liliane Rosine Kourogue Armand Wilfried Ndedy Bile Alain Rayane Mpouam Department of forestry Faculty of Agronomy and Agricultural Sciences University of Dschang Dschang Cameroon faculty of Science Department of Biology and Physiology of Plant Organisms University of Douala Douala Cameroon

One of the problems at the root of the poor management of forest resources in Cameroon is the lack of good governance. This study aims to evaluate the governance put in place by the government of Cameroon to ensure better management of Prunus africana. It takes a critical look at the three pillars of forest governance in relation to the management of the resource, which are: policy, legal, institutional and regulatory frameworks (1);planning and decision-making process (2);and finally the implementation, enforcement and compliance of regulations (3). The assessment was conducted using the guide recommended by fAO-PROfOR. Individual and focus group interviews were conducted with stakeholders involved in the P. africana management process. The results in the form of assessment scores revealed poor governance in the management of the resource. This is due to non-compliance with Pillars 2 and 3 on the planning and decision-making process as well as the implementation and enforcement of regulations through weaknesses in the principles of transparency, accountability, the effectiveness of management measures and stakeholder participation. These are the points on which management strategies should be based for better management of P. africana in the production forests of the Adamawa region.

关键词： forest Governance Prunus africana Stakeholders Pillars Components

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Spatio-Temporal Dynamic of Land Use and Land Cover in the Classified forest of Djoli-Kera, South-Eastern, Chad

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Open Journal of forestry 2018年第3期8卷 283-296页

作者： Lucie félicité temgoua Behimnan Allaissem Martin Tchamba Goy Saradoum Mbaiakambeye Mbaidje Osée Marie Caroline momo Solefack Department of forestry Faculty of Agronomy and Agricultural Sciences University of Dschang Dschang Cameroon Department of Biology University Institute of Agricultural Sciences and Environment Sarh Chad Department of Plant Biology Faculty of Science University of Dschang Dschang Cameroon

This study was carried out in the classified forest of Djoli-Kera found in the South-Eastern part of Chad. It aimed to analyze the spatial and temporal dy-namics of land cover between 1972 and 2013 and to determine the drivers of vegetation degradation. The databases used were made up of 4 Landsat satellite images (1MSS of 1972, 5TM of 1984, 7ETM+ of 1990 and 2010) and a spot 6 image of 2013, supplemented by field studies. Satellite images were processed using ENVI and ArcGIS software. Interview was used to identify the activities carried out by the local population. In 1972, the classified forest consisted of four types of land cover, the most important of which was open forest (51%), followed by wooded savannah (26%), tree savannah (21%) and sparse vegetation consisting of farms and fallows (2%). Gradually open forest and tree savannah disappeared. In 2013, the main types of land cover were shrub savannah (40%), sparse vegetation (28%), wooded savannah (12%), bare soil (12%) and dwellings (8%). Livestock, agriculture, wood collection and bushfires are perceived by local population as main drivers of forest cover change. Awareness-raising, monitoring and regulation of access to resources must be pursued, but also managers of the classified forest must accompany the local populations in the planting of trees and the setting up of more efficient farming systems to reduce pressure on the forest’s resources.

关键词： Land-Use Land-Cover Satellite Images Degradation Chad

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Plant Biodiversity and Structure of Robusta Coffee (Coffea canephora var. robusta) Agroforests in Cameroon

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Open Journal of forestry 2023年第2期13卷 225-241页

作者： Ngomeni Arlende flore Chimi Djomo Cédric Kabelong Banoho Louis Paul Roger temgoua Lucie félicité Avana Marie Louise Tchamba Ngankam Martin Bidzanga Nnomo Lucien Emmanuel Institute of Agricultural Research for the Development (IRAD) Yaounde Cameroon Institute of Agricultural Research for the Development (IRAD) Yokadouma Cameroon Plant Systematics and Ecology Unit Laboratory of Botany and Ecology Department of Plant Biology Faculty of Science University of Yaounde I Yaoundé Cameroon Laboratory of Environmental Geomatics Department of Forestry Faculty of Agronomy and Agricultural Sciences University of Dschang Dschang Cameroon

Agroforests are man-made ecosystems in which crops are associated with a main perennial species like Robusta Coffee Agroforests (RCAs), which is counted among the main modes of perennial crops production in Cameroon. Despite the rich ecosystem services provided, the diversity of Associated Species (AS) found in these RCAs and the structure of the landscapes they form remain little known in Cameroon. The current study aimed to inventory AS and characterize the structure of RCAs in four sites (Ayos, Malantouen, Melong and Nkongsamba) belonging to three robusta coffee production basins in Cameroon. A systematic inventory with dendrometric measurements of the wood AS and coffee trees was carried out on 120 one-hectare plot unit, i.e. 30 plots per site. The results showed that 102 AS belonging to 83 genera and 41 families were identified in these RCAs. The RCAs of Ayos in the dense rainforest zone with bimodal rainfall pattern were the most diverse with 71 species, followed by those of Melong and Nkongsamba with respectively 39 and 33 species respectively in the dense rainforest zone with monomodal rainfall pattern, and Malantouen with 33 species in the high savannahs of the west. Structurally, average coffee tree and AS densities founded ranged from 1208 - 1456 plants/ha and 71 - 214 stems/ha and those of basal area from 7.29 - 17.40 m2/ha for coffee trees and 7.97 - 16.14 m2/ha for AS in function of site. Basis on the vertical stratification, the proportion of the 3 - 6 m stratum, which is mainly represented by introduced AS, varied from 38% - 62% depending on the site. The results of this study showed that RCAs contribute to the conservation of plant biodiversity, given the specific richness identified in these ecosystems.

关键词： Associated Species Species Richness Horizontal Structure Vertical Structure Production Basin

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Chemical and Bacteriological Analysis of Drinking Water from Alternative Sources in the Dschang Municipality, Cameroon

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Journal of Environmental Protection 2011年第5期2卷 620-628页

作者： temgoua Emile 不详

In the poor zones of sub-Saharan Africa, the conventional drinking water network is very weak. The populations use alternative groundwater sources which are wells and springs. However, because of urbanization, the groundwater sources are degrading gradually making pure, safe, healthy and odourless drinking water a matter of deep concern. There are many pollutants in groundwater due to seepage of organic and inorganic pollutants, heavy metals, etc. Seventeen alternative water points created in 2008, for drinking water in Dschang municipality were examined for their physicochemical and bacteriological characteristics. The results revealed that water from managed points in Dschang is of poor quality. Most of the water samples were below or out of safety limits (standards) provided by WHO. The water is characterized by high turbidity and presence of feacal coliforms. It can be used for drinking and cooking only after prior treatment. This situation shows that water point management was limited only to the drawing up comfort. These water points require installation of suitable surfaces of filtration and the development of a chlorination follow-up plan. Specific concerns of well water were raised and the management options to be taken proposed.

关键词： Sub-Saharan Region Alternative Water Assessing Point Water Quality

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Land Use and Land Cover Change Analysis in Ajei Upland Watershed Community forest, North West Region, Cameroon

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Journal of Geoscience and Environment Protection 2018年第9期6卷 83-99页

作者： Lucie félicité temgoua Gordon Ajonina Hans Berinyuy Woyu Department of forestry Faculty of Agronomy and Agricultural Sciences University of Dschang Dschang Cameroon Cameroon Wildlife Conservation Society Mouanko Cameroon

This study was carried out in Ajei upland watershed community forest in the North West Region of Cameroon with the aim to analyze spatial and temporal dynamics of land cover and land use from 1988 to 2018 and to identify and characterize the agents, drivers and pressures of this change. The databases used were made up of 3 Lands at satellite images (5 TM of 1988, 7ETM+ of 2003 and 8OLI of 2018). field survey, interview and focus group discussion methods were used to identify the activities carried out by the local population and to determine agents, drivers and pressures of land use and land cover change. The Ajei community forest is consisted of four main land cover namely;dense vegetation, sparse or degraded vegetation, savanna and bare soil. Between 1988 and 2018, the proportions of dense vegetation and savanna decreased and that of bare soil and sparse vegetation increased. Analysis showed ongoing deforestation with forest cover loss of about 240 ha in 30 years. for the considered time periods 1988-2003 and 2003-2018, deforestation rates were 1.83% per year and 1.49% per year respectively, signifying on average 8 hectares of forest cover undergoing conversion each year. This lost results from the actions of farmers, cattle grazers and wood extractors who through farming, grazing and lumbering activities pressurize and convert the dense forest cover. Economic motives notably the need to increase household income from a frequent demand for farm and wood products in nearby markets represent the drivers of forest cover change. Controlling grazing activities notably in the dry season to check out the use of fires, community sensitization especially among cattle headmen on the importance of the community forest, reforestation activities through natural regeneration or tree planting are needed in the forest.

关键词： Land Use Land Cover Change Agents Drivers Pressures

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