Reflection coefficient of natural vegetation, crops and urban surfaces in Nigeria

Oguntoyinbo, Julius S.

doi:10.1002/qj.49709640907

Cited by 76 publications

(28 citation statements)

References 16 publications

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“…Results there have ranged between 0.1225 (Shuttleworth et al, 1984) and 0.134 (Culf et al, 1995). Measurements taken elsewhere are in general agreement with Amazonian values, with 0.12 found in Nigeria (Oguntoyinbo, 1970) and 0.13 in Thailand (Pinker, 1982). Albedo of deforested tropical surfaces is more variable, dependent on the replacement land cover.…”

Section: Albedo Of Tropical Land Surfaces: Previous Researchsupporting

confidence: 73%

“…Bastable et al (1993), Fisch et al (1994), and Culf et al (1995) obtained albedo for Amazonian pasture ranging from 0.163 to 0.190. Oguntoyinbo (1970) found albedo ranged from 0.15 to 0.21 for nonforested locations in Nigeria. Pinker (1982) measured a mean albedo of 0.150 for tall grass in a forest clearing in Thailand.…”

Section: Albedo Of Tropical Land Surfaces: Previous Researchmentioning

confidence: 95%

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Dry-season radiation balance of land covers replacing forest in northern Thailand

Giambelluca

Fox

Yarnasarn

et al. 1999

Agricultural and Forest Meteorology

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The results of numerous general circulation model (GCM) experiments of climatic effects of extensive tropical deforestation include signi®cant reductions in regional precipitation. However, the simulated precipitation decrease is highly dependent on the large albedo shift associated with the assumed conversion of forest into grassland. Land cover change surveys of the Amazon and Thailand suggest that secondary vegetation at various growth stages, rather than grassland, is the dominant feature of deforested land. In this paper, we present ®eld measurements, taken during the dry season, of radiative characteristics of various deforested land surfaces in montane northern Thailand, including secondary vegetation. Dry-season albedo at nine sites in the village of Pang Khum, Chiang Mai Province, ranged from 0.085 for irrigated bare soil to 0.171 for 3-year secondary vegetation. As a result of increased albedo and higher daytime surface temperature at exposed dry soil sites, net radiation is reduced substantially. Regional mean dry-season albedo is estimated to have increased from 0.13 to 0.144 by 1980 for all of northern Thailand, and from 0.13 to 0.14 by 1983 for the southern portion of Sam Mun watershed, the 10 000 ha area immediately surrounding the study site. Continuing signi®cant upward trends in regional albedo at both spatial scales are suggested by the estimates. However, our measurements suggest a maximum deforestation-induced albedo increase of about 0.04, half that used to simulate the effects of deforestation in most GCM experiments. It is likely, therefore, that simulated reductions in precipitation in the region due to deforestation will not be seen in model runs using more realistic scenarios of post-deforestation land cover characteristics. #

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Section: Albedo Of Tropical Land Surfaces: Previous Researchsupporting

confidence: 73%

Section: Albedo Of Tropical Land Surfaces: Previous Researchmentioning

confidence: 95%

Dry-season radiation balance of land covers replacing forest in northern Thailand

Giambelluca

Fox

Yarnasarn

et al. 1999

Agricultural and Forest Meteorology

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“…RR followed RG, representing 14%-19% (surface albedo, α0) of its values, despite having higher spatial variations when compared to RG, and according to moisture conditions and ecosystem characteristics. Monteith and Unsworth [38] [39][40][41]. These similarities confirm the validity of Equation (1) applied to MODIS images for the Pantanal ecosystems.…”

Section: Large-scale Radiation Balancesupporting

confidence: 69%

Use of MODIS Images to Quantify the Radiation and Energy Balances in the Brazilian Pantanal

et al. 2015

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MODIS images during the year 2012 were used for modelling of the radiation and energy balance components with the application of the SAFER algorithm (Simple Algorithm for Evapotranspiration Retrieving) in the Brazilian Pantanal area. Pixels from the main sub-regions of Barã o de Melgaç o (BR), Paiaguá s (PA) and Nhecolâ ndia (NH) were extracted in order to process microclimatic comparisons. In general, the net radiation (Rn) relied much more on the global solar radiation (RG) levels than on water conditions and ecosystem types, in accordance with the low Rn standard deviation values. The fraction of the available energy used as latent heat flux (λE) were, on average, 65, 50 and 49% for the BR, PA and NH sub-regions, respectively. Horizontal heat advection, identified by the negative values of sensible heat flux (H), made several pixels with λE values higher than those for Rn in the middle of the year. Taking the evaporative fraction (Ef) as a surface moisture indicator, the Tree-Lined Savanna (TLS) was considered the moister ecosystem class, with 58% of the available energy being used as λE, while the driest one was the modified ecosystem Anthropogenic Changes (AC), presenting a λE/Rn fraction of 0.46. According to the spatial and temporal consistencies, and after comparisons with other previous point and large-scale studies, the SAFER algorithm proved to have sensibility to quantify and compare the large-scale radiation and energy balance components in the different ecosystems of the OPEN ACCESS Remote Sens. 2015, 7 14598Brazilian Pantanal. The algorithm is useful for monitoring the energy exchange dynamics among the different terrestrial and aquatic ecosystem types throughout the seasons of the year.

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“…Others are increased rainfall that is accompanied by devastating storms and urban floods. Viewing these enormous problems and the earlier call by [1], some urban climate studies in Nigeria have examined the urban influence on components of climates characteristics namely: global radiation [5] [26], net radiation [26], temperature and albedo [4] [5] [27]. These studies showed that while net radiation and albedo values in urban are lower than the values measured in rural area, temperature is higher in urban areas than in rural areas.…”

Section: Introductionmentioning

confidence: 99%

Urban Warming in Benin City, Nigeria

Efe¹,

Eyefia²

2014

ACS

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The study examined urban effects on the temperature of Benin City. The data used for this study were generated from archives of the Nigerian Meteorological Agency Benin City and the Agrometeorological Station of NIFOR, and mobile transverse method of collecting temperature data at different land use types in the urban canopy for one year. Paired t-test and analysis of variance were used to determine the differences in temperature in the area. The findings revealed an urban bias of 4.4˚C, and variation of 5.5˚C in temperature within the urban canopy, which confirmed the concept of urban heat island. It also showed an urban-rural temperature differential of 0.5˚C, which indicated an urban warming of 2% over its rural areas. Daily temperature revealed that the working days are warmer than the weekends. High rate of anthropogenic activities, which act as drivers of heat island in the urban area accounted for the increase in temperature. The study therefore recommends urban planning with green city-green roof approach.

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Reflection coefficient of natural vegetation, crops and urban surfaces in Nigeria

Cited by 76 publications

References 16 publications

Dry-season radiation balance of land covers replacing forest in northern Thailand

Dry-season radiation balance of land covers replacing forest in northern Thailand

Use of MODIS Images to Quantify the Radiation and Energy Balances in the Brazilian Pantanal

Urban Warming in Benin City, Nigeria

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