19 research outputs found
Confirmation of Climate Change in Southwestern Nigeria through Analysis of Rainfall and Temperature Variations over the Region
Understanding the variability of precipitation and temperature of a region over a long period gives one an idea about the climate and climate change of such region. The study investigated rainfall and temperature variability in four meteorological stations, namely, Abeokuta (lat.7.01o N, long.3.2o E, alt. 67m) , Ibadan (lat.7.43o N, long.3.9o E, alt. 227m), Ikeja (lat.6.58o N, long.3.33o E, alt. 39m ) and Ondo (lat.7.1o N, long.4.83o E , alt. 287m) in the south-western region of Nigeria.Monthly rainfall, minimum temperature and maximum temperature data were obtained from Nigeria Meteorological Agency (NIMET) for the period of thirty one years (1980 to 2010) for the study.Descriptive Statistics were deployed to determine the mean, confidence levels, coefficient of kurtosis, skewness and coefficient of variations. A fairly “M-shaped” pattern was observed in the monthly mean rainfall distribution with bi-modal peaks in June and September, with slight dryness experienced in August, referred to as “August break”. Analyses of annual trends over a long period revealed a sequence of alternately decreasing and increasing trends in mean annual rainfall and air temperature in region. Generally however, gradients of the trend lines are positive. There is a negative relationship between annual total rainfall and annual average temperature
Storm-time variation of the horizontal and vertical components of the geomagnetic fields and rate of induction at different latitudes
The paper presents the hourly mean variation of horizontal (H) and vertical (Z) components of the geomagnetic field and the rate of
induction DH/DZ at different latitudes during magnetic storm of 20 March 2001 and 1 October 2001. The results of the analysis revealed
that at high latitude stations greater than 60ďż˝, the reduction in DH component was noticed after the noon time while other stations less
than 60ďż˝ experienced reduction of H in the morning time during the geomagnetic storm. Large amplitude of DH and DZ were exhibited
during the daytime over the equatorial zone, the amplitude decreases from mid latitudes to the dip equator during the nighttime. The
daytime enhancement of DH at AAE, BAN and MBO suggest the presence of a strong eastward directed current which comes under
the influence of electrojet. There were strong positive and negative correlations between ring current (DR) and horizontal component
of the magnetic field DH. The effect of rate of induction is more significant at high latitudes than lower latitudes, during the geomagnetic
storm. More enhancement in rate of induction occurred at nighttime than daytime. This result may be from other sources other than the
ionosphere that is magnetospheric process significantly contributes toward the variation of induction
Natural Radioactivity and Hazards in Soil Samples in Alade Community, Southwestern Nigeria
The concentrations of natural radionuclides in Alade community, Ado-Odo/Ota Local Government Area were determined using gamma ray spectrometer comprising a 7.6 cm x 7.6 cm Nal(TI) detector coupled to a multichannel analyser for spectral analysis. A total of 20 soil samples were collected from different locations in Alade community, Ado-Odo/Ota Local Government, Ogun state, Nigeria. Data were analysed using descriptive statistics. The activity concentration obtained were in ranges of 45.62 ± 2.53 Bq/kg to 665.25 ± 35.11 Bq/kg with mean value of 352.34 ± 18.67 Bq/kg for 40K, 2.32 ± 0.47 to 54.56 ± 6.20 Bq/kg with mean value of 19.86 ± 2.56 Bq/kg for 238U and 4.34 ± 0.28 Bq/kg to 23.10 ± 1.40 Bq/kg with mean value of 14.22 ± 0.87 Bq/kg for 232Th. The study evaluated radiation hazard indices, the mean values obtained were, 64.55 ± 5.05 Bq/kg for Radium equivalent activity (Raeq), 32.86 ± 2.53 nGyh-1 for Absorbed Dose Rate (D), 40.30 ± 3.10 µSvy-1 for Annual Effective Dose Equivalent (AEDE), 0.18 ± 0.01 for External Hazard Index (Hex) and 0.22 ± 0.02 for Internal Hazard Index (Hin). These calculated hazard indices were well below their permissible limit. The results obtained for the mean activity concentrations values from 20 soil samples from Alade community, revealed that 40K, 238U and 232Th values were below the United Nations Scientific Committee on the Effects of Atomic Radiation recommended international limits of 370Bq/kg and within the tolerance level indicating minimal radiological health burden on the Alade community and its environment
Impact of meteorological parameters over Covenant University, Ota, Nigeria
This study utilized monthly daily values of solar radiation, humidity, ultraviolet
dose, temperature, pressure and wind speed obtained at Department of Physics, Covenant
University, Ota, Nigeria, for 2013. It was observed that correlation coefficients vary from
0.134 - 0.955 across the months. This was further demonstrated with values of coefficient
of determination R2 which vary from 0.018-0.911 for Ota stations. Based on the RMSE,
MPE, MBE and p values, we obtained an Equation that produces the best correlation. Our
result reveals the models that produce the smallest p values which are considered as the best
model for estimating the solar radiation at Ota site with an acceptable error. Also, Wavelet
spectrum based approach was employed to analyse the meteorological monthly series in a
sequence of monthly scales of January to December 2013
Proximate Composition and Metabolizable Energy of Some Commercial Poultry Feeds Available in Abuja, Nigeria
Poultry feeds are prepared to contain all the nutrients in their right proportions necessary for good health, proper growth and egg production of the chicken. This study was undertaken to determine the proximate composition and variations of nutrient in some commercial poultry feeds sold in Abuja, Nigeria. Seven poultry feed brands in their various ratios were subjected to proximate analysis using standard methods. The results of the analysis revealed that the poultry feeds had proximate composition ranging from 6.58 ± 0.02 - 10.88 ± 0.19 % moisture content, 6.03 ± 0.16 - 14.78 ± 0.73 % ash content, 9.98 ± 0.81 - 20.05 ± 0.08 % crude lipid, 3.57 ± 0.11 - 14.77 ± 0.14 % crude fiber, 16.55 ± 0.07 % - 34.01 ± 0.09 % crude protein, 26.28 ± 1.80 % - 48.21 ± 2.07 % carbohydrate and 2971.48 ± 65.44 - 3686.18 ± 29.08 Kcal/kg metabolizable energy. Generally, there were differences in the proximate composition of the poultry feed brands analyzed, however, the poultry feeds have optimum nutrients in their feeds which meet most of the requirements recommended by SON and NRC. The moisture contents in all the feeds were within the recommended value of not more than 12 % while the mean values obtained in crude lipid were all higher than the maximum recommended requirements in poultry feeds
Observation of the Total Electron Content for 14- GPS stations in Malaysia during the Annular Eclipse of 15th of January 2010
The paper examines the Ionospheric response to
the annular eclipse of the sun on January 15, 2010 over eastern
and western Malaysia using GPS data measurement from 14-
ground station in Malaysia. The GPS sensing technique employs
two different approaches to verify the TEC depletion occurrence
at the 14-stations. The first approach measures the TEC
depletion parameters at the 14 GPS stations during the solar
event. The second approach compares the TEC value with the
quiet day TEC variation at one of the station 3-days before and
3-days after the solar eclipse event. The GPS observation
indicates occurrence of TEC depression at 6 stations where the
behaviour varying from one station to another. On the basis of
the first and second measurement techniques, the range of TEC
depletions at the six stations were 9 to 20 %, while for the other
8-stations 0.4 to 12% respectively. The measurement shows that
TEC depression at most GPS stations began on the neck of the
first contact of the solar eclipse followed by deeper depressions.
This effect was as a result of the hiding of the optical rays during
the solar eclipse which causes direct reduction in photo
ionization; destroy the previous photo-chemical equilibrium and
result in the depletion in electron density
Estimating geomagnetically induced currents at sub-auroral and low latitudes to assess their effects on power systems
During large magnetic storm the geomagnetically induced current has a negative impact on ground conducting technology systems. The time derivative of the horizontal component of the geomagnetic field (dH/dt) is greater than 30nT/min for induced currents causing undesirable consequence in power grids. Multiple regression analyses were developed to predict the level of geomagnetic disturbance using time derivatives of the horizontal geomagnetic field, east and north components of the geoelectric field, auroral electrojet and disturbance storm times from 1994-2007 at low and subauroral latitudes. The statistical test RMSE (Root Mean Square Error) and MBE (Mean Bias Error) were employed to evaluate the accuracy of the geomagnetic disturbance. Different variables have been used to develop different types of models. Values of the correlation coefficient and the coefficient of determination were high, which indicates that the results are good. The equations produced the best correlations at subauroral and low latitudes, and the best correlation was obtained with low values of RMSE and MBE
Variations of time derivatives of the horizontal geomagnetic field and horizontal geomagnetic field along 96-degree magnetic meridian
The Energetic particles are released from the Sun by solar flares or eruptive ejections interaction with geomagnetic field producing geomagnetic storms and more ionization in the ionosphere. The geomagnetic substorms are classified as one of major factor that influence geomagnetically induced currents (GIC) that affect the operation of technological system through the geomagnetic field variations. The direct representation of GIC is the time derivative of the horizontal geomagnetic field. 138 substorms onset events were obtained from IMAGE magnetometer data from Northern Europe, using Dst (Disturbance storm time) to determine the substorm events of varying strengths, for five stations (Addis Ababa, Abisko, Bangui Hermanus and Nurmijarvi). The data used in this study covers the periods from 1999 to 2001. Positive high correlation exhibited between the maximum value of time derivatives of the horizontal geomagnetic field (dH/dtmax) and maximum value of horizontal geomagnetic field (max H). Also, Monthly variations of the maximum value of time derivatives of the horizontal geomagnetic field (dH/dtmax) and maximum value of the horizontal geomagnetic field (max H) were also investigated
Asymmetry in Seasonal Variation of Geomagnetic Activity
Seasonal variations in geomagnetic activities were studied for the period of 1990-2007 using Dst and AE indices. Over 150 events characterised by increase in geomagnetic activity of varying strength (from -90 up to -1800nT) were statistically analysed. Although Russell- McPherron effect plays a major role in the equinoctial asymmetry of the geomagnetic activity, others may also take place. During this study we found a statistically significant October-November peak in geomagnetic activity for Northern Hemisphere, which is sufficiently larger than March-April peak. Several hypotheses for the cause of such effect are discussed