Measurements of net all-wave radiation at a tropical location, Ile-Ife, Nigeria

Hourly averaged net all-wave radiation data spanning a complete three-year period (2010-2012) at a meteorological station located inside the Obafemi Awolowo University campus in Ile-Ife (7.52º N, 4.52º E), Nigeria is presented in this study to investigate its diurnal and seasonal variations. Using a high-sensitivity four-component net radiometer, the data represents so far the most consistent and detailed information available for a tropical location in West Africa. From the dataset, hourly maxima of the net radiation occurred at 14:00 LT (GMT + 1), whose values increased considerably from 337.6 ± 146.4 Wm–2 in July, which is the peak of the wet season, to 441.7 ± 82.4 Wm–2 in March, the end of the dry season. April and October, both of which mark the beginning and end of the raining season at Ile-Ife have recorded the highest values of 584.7 and 612.2 Wm–2, respectively. There was strong intra/inter-seasonal variation observed in the monthly mean values of the net radiation due mainly to the fluctuations in cloudiness and humidity. In the study area, the data indicated a net radiative heating taking place at the surface, whose annual trend follows a bimodal distribution. The present data supports the results published in earlier studies by other authors.Se presentan datos de radiación neta en todas las longitudes de onda promediados cada hora, registrados en una estación meteorológica situada en el campus de la Universidad Obafemi Awolowo, Ile-Ife (7.52º N, 4.52º E),Nigeria, durante un periodo completo de tres años (2010-2012), para estudiar sus variaciones diurnas y estacionales. Esta información, obtenida con un radiómetro neto de alta sensibilidad de cuatro componentes, representa hasta hoy la información más consistente y detallada disponible para una localidad tropical de África Occidental. De acuerdo con los datos obtenidos, la radiación neta máxima ocurrió a las 14:00 LT (GMT + 1),y sus valores se incrementaron de manera considerable de 337.6 ± 146.4 Wm–2 en julio, que es el pico de la estación lluviosa, a 441.7 ± 82.4 Wm–2 durante marzo, en el final de la estación seca. En los meses de abril y octubre, que marcan el principio y fin de la estación lluviosa en Ile-Ife, se han registrado los valores más altos de radiación neta: 584.7 y 612.2 Wm–2, respectivamente. Se observó una importante variación inter e intraestacional en los valores medios mensuales de radiación neta, debida principalmente a fluctuaciones de nubosidad y humedad. En el área de estudio, los datos revelaron la presencia de calentamiento radiativo neto en la superficie, cuya tendencia anual sigue una distribución bimodal. Los datos de este estudio respaldan los aportados por otros autores

Advancing human nutrition without degrading land resources through modeling cropping systems in the Ethiopian highlands

Food shortage in sub-Saharan Africa is generally considered a function of limited access to food, with little thought to nutritional quality. Analyzing household production of nutrients across farming systems could be valuable in guiding the improvement of those systems. An optimization model was employed to analyze the scenario of human nutrition and cropland allocation in enset (Enset ventricosum)/root crop-based and cereal-based systems of the Ethiopian Highlands. The type and amount of nutrients produced in each system were analyzed, and an optimization model was used to analyze which cropping strategies might improve the nutritional quality of the household using existing resources. Both production systems were in food deficit, in terms of quantity and quality of nutrients, except for iron. The energy supply of resource-poor households in the enset/root crop-based system was only 75% of the recommended daily dietary allowance (RDA) of the World Health Organization (WHO), whereas resource-rich farmers were able to meet their energy, protein, zinc, and thiamine demands. Extremely high deficiency was found in zinc, calcium, vitamin A, and vitamin C, which provided only 26.5%, 34%, 1.78%, and 12%, of the RDA, respectively. The RDA could be satisfied if the land area occupied by enset, kale, and beans were expanded by about 20%, 10%, and 40%, respectively, at the expense of maize and sweet potato. The cereal-based system also had critical nutrient deficits in calcium, vitamin A, and vitamin C, which provided 30%, 2.5%, and 2% of the RDA, respectively. In the cereal system, the RDA could be fully satisfied by reducing cropland allocated to barley by about 50% and expanding the land area occupied by faba beans, kale, and enset. A shift from the cereal/root crop-dominated system to a perennial-enset dominated system would decrease soil erosion by improving the crop factor by about 45%. This shift would also have a very strong positive impact on soil fertility management. However, any policy suggestions for change in cropland allocation should be done through negotiations with households, communities, and district stakeholders

Analysis of the variability of airborne particulate matter with prevailing meteorological conditions across a semi-urban environment using a network of low-cost air quality sensors.

The concentrations of fine and coarse fractions of airborne particulate matter (PM) and meteorological variables (wind speed, wind direction, temperature and relative humidity) were measured at six selected locations in Ile Ife, a prominent university town in Nigeria using a network of low-cost air quality (AQ) sensor units. The objective of the deployment was to collate baseline air quality data and assess the impact of prevailing meteorological conditions on PM concentrations in selected residential communities downwind of an iron smelting facility. The raw data obtained from OPC-N2 of the AQ sensor units was corrected using the RH correction factor developed based k-Kohler theory. This PM (corrected) fast time resolution data (20 s) from the AQ sensor units were used to create daily averages. The overall mean mass concentrations for PM2.5 and PM10 were 213.3, 44.1, 23.8, 27.7, 20.2 and 41.5 μg/m3 and; 439.9, 107.1, 55.0, 72.4, 45.5 and 112.0 μg/m3 for Fasina (Iron-Steel Smelting Factory, ISSF), Modomo, Eleweran, Fire Service, O.A.U. staff quarters and Obafemi Awolowo University Teaching and Research Farm (OAUTRF), respectively. PM concentration and wind speed showed a negative exponential distribution curve with the lowest exponential fit coefficient of determination (R2) values of 0.08 for PM2.5 and 0.03 for PM10 during nighttime periods at Eleweran and Fire service sites, respectively. The relationship between PM concentration and temperature gave a decay curve indicating that higher PM concentrations were observed at lower temperatures. The exponential distribution curve for the relationship between PM concentration and relative humidity (RH) showed that PM concentrations do not vary for RH 80 % for both day and nighttime. The performances of the MLR model were slightly poor and as such not too reliable for predicting the concentration but useful for improving predictive model accuracy when other variables contributing to the variability of PM is considered. The study concluded that the anthropogenic and industrial activities at the smelting factory contribute significantly to the elevated PM mass concentration measured at the study locations

Measurements of net all-wave radiation at a tropical location, Ile-Ife, Nigeria

AbstractHourly averaged net all-wave radiation data spanning a complete three-year period (2010-2012) at a meteorological station located inside the Obafemi Awolowo University campus in Ile-Ife (7.52° N, 4.52° E), Nigeria is presented in this study to investigate its diurnal and seasonal variations. Using a high-sensitivity four-component net radiometer, the data represents so far the most consistent and detailed information available for a tropical location in West Africa. From the dataset, hourly maxima of the net radiation occurred at 14:00 LT (GMT + 1), whose values increased considerably from 337.6 ± 146.4 Wm−2 in July, which is the peak of the wet season, to 441.7 ± 82.4 Wm−2 in March, the end of the dry season. April and October, both of which mark the beginning and end of the raining season at Ile-Ife have recorded the highest values of 584.7 and 612.2 Wm−2, respectively. There was strong intra/inter-seasonal variation observed in the monthly mean values of the net radiation due mainly to the fluctuations in cloudiness and humidity. In the study area, the data indicated a net radiative heating taking place at the surface, whose annual trend follows a bimodal distribution. The present data supports the results published in earlier studies by other authors

Evaluation of the Performance of some Evapotranspiration Models at a Tropical Location in Ile – Ife, Nigeria

This study evaluates the performance of some evapotranspiration models at Ile – Ife (7o 33’ N, 4o 33’ E) Nigeria. This was to identify suitable evapotranspiration (ET) models at the study site and to provide useful information for standardizing evapotranspiration estimations at a tropical location. Meteorological parameters (wind speed, relative humidity, temperature, solar radiation, soil heat flux, and net radiation) were routinely measured at the Obafemi Awolowo University (OAU) Meteorological Station located within the Teaching and Research Farm of the campus for a period of a month (1st – 29th July 2014). Nine standardized models for the estimation of ET; Penman-Monteith (FAO-56 PM), Priestly-Taylor (PT), Makkink (MAKK), Jensen-Haise (JH), Hargreaves-Samani (HS), Ivanov (IVA), Modified Romanenko (MROM), FAO-24 Radiation (FAO-24 RAD) and Turc (TURC) models were employed. The ET values obtained from these models were then compared to the estimated values obtained from the FAO-56 PM equation recommended as the international standard method for determining reference ET. The estimation of the ET obtained from FAO – 56 PM model ranged between 0.426 – 2.239 mm/day, MAKK, JH, and HS gave estimation closest to this, ranging from 0.544 – 2.272 mm/day. The estimation of ET from other models revealed that PT has the highest value ranging between 1.323 – 6.936 mm/day, followed closely was FAO – 24 RAD with values ranging between 1.197 – 6.500 mm/day, values of IVA model ranged from 0.620 – 1.829 mm/day, MROM value ranged from 1.240 – 3.659 mm/day, TURC has the least value ranging from 0.190 – 0.584 mm/day. Using the result of the mean biased error and regression analysis, JH model compared best with the FAO – 56 PM with coefficient of determination (R2) = 0.927; slope (b) = 0.957; mean biased error (MBE) = 0.133, this was followed closely by HS with value R2 = 0.929; b = 1.199; MBE = - 0.075 and MAKK with the value R2 = 0.931; b = 1.198; MBE = - 0.052. However, the other models showed significant over or underestimation of the ET benchmark values. The performance of the other models showed no improvement after they were recalibrated by adjusting their original coefficients. Thus, six out of the ET models employed in this study [the Priestly-Taylor (PT), Makkink (MAKK), Jensen-Haise (JH), Hargreaves-Samani (HS), FAO-24 Radiation (FAO-24 RAD) and Turc (TURC)] were found suitable for the climatic region of Ile – Ife after the adjustment of their coefficients.</jats:p