Comparative Analysis of Total Ozone Data from Satellite EPTOMS and Ground-Based Dobson Instrument at Lagos-Nigeria

This work represents a comparison study of total ozone data from the ground-based Dobson spectrophotometer and the overpass data from satellite instrument EPTOMS in Lagos-Nigeria (Lat.6.6oN, Long 3.3oE) for the year 1997-2002. The result indicated that EPTOMS ozone series overestimated those of the Dobson’s maximally between July-September with an average difference of 11%, while the Dobson ozone profile exceeded the EPTOMS by 6% in the month December-January. A strong anti-correlation of -0.88 was observed between the Dobson’s ozone profile and the EPTOMS in the month July-September. The Dobson data showed considerable high frequency fluctuations with no clear seasonal trend. Maximum inter-annual differences for both instruments fell within the period of low precipitation in the West Africa region. Despite the monthly differences in the two set of data, their seasonal and annual component showed significant positive correlation of 0.53 with each othe

MODELING OF GENERIC AIR POLLUTION DISPERSION ANALYSIS FROM CEMENT FACTORY

Air pollution from cement factory is classified as one of the sources of air pollution. The control of the air pollution by addressing the wind field dynamics was the main objective of the paper. The dynamics of dispersion showed a three way flow which was calculated and explained accordingly. The 3D model showed good level of accuracy by determining field values of air deposited pollutants. Mean concentration of diffusing pollutants was shown to be directly proportional to the plume angular displacement. The 2D model explained the details of the wind field dynamics and proffers a solution which may be relevant in controlling air pollution from anthropogenic sources. Key words: contaminant, advection, drag force, semi-plume mode

The Influence of Some Atmospheric Phenomena on Total Ozone Concentration over the Tropics

The influence of some atmospheric phenomena such as the Quassi Biennial Oscillation, the El Nino Southern Oscillation (ENSO) and the extratropical suction pump action on total ozone concentration over the region spreading from latitude 30o south to 30o north were studied using satellite data from 1997 to 2002. These phenomena were observed to contribute significantly to the variability of ozone concentration over the region. The region was divided into twelve latitudinal zones of 5o each. The equatorial zones 50S-50N recorded high percent variability above 6.5% in at least nine months of the year. This may be attributed to the extra-tropical suction pump action been strongest over the two zones closest to the equator. Zone 300S-250S recorded a high stability in ozone concentration in March in the six years studied with average variability of 0.7%. The six northern zones recorded higher values of annual coefficient of relative variation (ACRV) of ozone than their southern counterparts in the six years studied with average value of 5.0% and 3.0% respectively. There was a peculiarity in the ozone concentration in 1998, which was a year of El Nino Southern Oscillation (ENSO) occurrence. The ACRV of ozone concentration almost doubled the average zonal values especially at the southern tropics. At zones 50S - 150S, the average ACRV in 1998 was 4.3% while the average ACRV for the other five years studied was 2%. In the northern tropics, the values of ozone concentration at zones 00-150 north were very close with a correlation of 0.99, between September to December of the years 1997, 1999 and 2002, while there were noticeable degrees of disparities in the other periods studied. This was attributed to the effect of quasi-biennial oscillation (QBO) at the region in these periods

Dependence of UV-B Radiation on Ozone Concentration and Solar Zenith Angle at Three African Stations

No Abstract

Application of Fast Fourier Transform to Ozone Data at Lagos, Nigeria

Fast Fourier Transform (FFT) is a mathematical too l often used to represent tim e-varying real data set function /(1). In this paper, the FFT was applied to the measured stratospheric ozone data at Lagos from 1997 to 2002. The total number of data set used was 211 giving 2048. Both first order and second order derivatives of the data set were generated using FFT. The total ozone data over Lagos was latter generated using the derivatives. The simulated ozone data was compared with the observed ones. The mean ozone concentration value from the observed data was 270.8±0.3D U, its standard deviation was 15.3DU and its range 93.1 D U. For FFT (N - 2048) generated data, its mean was 27 1. 2±0.3DU, its standard deviation was 15.5DU and its range was 79.8D U. The re sult of the generated data us ing FFT of (N - 2048), and that of the observed values had a correlation of 0.99 while that of (N- 1024) had a correlation value of 0.94. The rate of depletion of ozone in January and February was also observed to have average values of -0.14DU per day with an average initial valw: of about 250DU. Similarly the rate of increase in ozone in .July to September was about 0. 3DU per day with an average initial value of about 28 0D U

Wind Convolution and Ozone Distribution over Nigeria

The effect of zonal and meridional wind on surface ozone variability in Nigeria in the four quarter of the year was explored using data from Atmospheric Infrared sounder (AIRS) of NASA. Namely, December, January, February (DJF); March, April, May (MAM); June, July, August (JJA) and September, October, November (SON). The study revealed that both the day and night time surface ozone distribution in DJF season recorded a significant correlation of 0.7 with the zonal wind flow pattern, and a less significant correlation of 0.36 with the meridional wind flow pattern. Average maximum ozone concentration of 281.4DU southward and 260.3DU northward were observed in DJF. In JJA, the meridional wind pattern recorded strong west to east flow which was non-parallel to the latitudinal lines. It had a significant negative-correlation of – 0.56 with the ozone distribution for that season.Also the JJA zonal wind flow unlike that of DJF, recorded significant west to east flow resulting in partial atmospheric blocking which constrained the maximum ozone concentration westward with an average of 307DU retained within longitudes 2oE - 6oE in western Nigeria, for all the seven years studied. This was contrary to the direction of the prevailing meridional flow for the season which was predominantly eastward

Diminishing Atmospheric Carbon Monoxide fluxes as a Forecast of the New Planting Season in West Africa

This paper studied the variability of background Carbon Monoxide CO fluxes from 2000 to 2010 as released by satellite observatory system from the Measurement of Pollution in the Troposphere (MOPITT) instrument over the West African region, from latitude 2o N to 15 o N. From the twelve months of the year studied, the data for December and January to April followed a particular trend which was observed to be relevant in the forecasting of the following planting season over the region. The study revealed that the background CO fluxes averaged about 300ppbv in December and January and gradually reduces to about 220ppbv and 170ppbv in March and April respectively. This trend was observed in the ten years studied. It could be suggested thus that an average 35% to 45% decrease in December/January CO fluxes accumulation is a pointer to the beginning of the next planting season in the West African region. It was also observed that as the background CO flux dwindled, the locations of high CO concentrations due to fossil fuel combustions and other anthropogenic activities were more distinct in comparison to the rest of the region

Analysis of Radiation Dose around Some Base Stations in Ota and Lagos Environ

The aim of this work is to investigate radiation dose around some GSM base stations within Ota and Lagos metropolis in Nigeria. This was done using a radiation alert monitor (M4EC) manufactured by S.E. International, Inc., USA. The measurements were carried out on ten different masts cited in some places in Ota Ogun State and Lagos. Measurements were carried out by positioning the radiation meter at five various distances to the masts and the mean value considered. The study showed that there is presence of radiation levels from masts beyond the background radiation levels but is within the permissible limit for public. The radiation dose measured where one mast was erected varied between 0.001 and 0.027 x 10-3 mSv/week. The radiation measured from location where two masts were erected varied between 0.001 and 0.039 x 10-3 mSv/week. The radiation measured where three masts were erected vaied between 0.001 and 0.050 x 10-3 mSv/week. The highest equivalent dose was obtained at 1 m away from the masts where three masts are erected and the radiation went to minimum at 16 m away from the masts. Also, where one mast was erected the highest radiation was measured at 1 m and went to minimum at 6m away from the mast except for BS 3 with the shortest mast 84 ft where minimum radiation was obtained at 8 m from the mast. It can be concluded that radiation dose depends on the number of mast erected in a particular location which implies that the more the number of masts in a location the more the distance should be kept from them. The study showed that the height of the mast plays significant roles in the radiation incurred by people around, in other words, the higher the mast, the safer it is for those around it. Technicians should be advised to desist from crowding a location with too many masts since the higher the number of masts the higher the radiation incurred the mast should be of appropriate height

Modeling of Generic Air Pollution Dispersion Analysis from Cement Factory

Air pollution from cement factory is classified as one of the sources of air pollution. The control of the air pollution by addressing the wind field dynamics was the main objective of the paper. The dynamics of dispersion showed a three way flow which was calculated and explained accordingly. The 3D model showed good level of accuracy by determining field values of air deposited pollutants. Mean concentration of diffusing pollutants was shown to be directly proportional to the plume angular displacement. The 2D model explained the details of the wind field dynamics and proffers a solution which may be relevant in controlling air pollution from anthropogenic source

Monitoring of Radiofrequency Radiation from Selected Mobile Phones

Investigation of possible presence of radiofrequency radiations from mobile at distance not less than 20cm was carried out within Covenant University, Ota, using ten different handsets. Radiation measurement was carried out using a cell sensor manufactured by Action Electronic, USA that is optimized to measure radiofrequency and extremely low frequency radiation. The average power density from the handsets was 0.10mW/cm2 and 0.45mW/cm2 with highest value from both NOKIA 1100 and SAGEM My X5 and lowest from SAGEM My X1 at distance not less than 20cm. These results show that those using handsets are exposed to radiation beyond the background levels but are within the limit set by the Federal Communication Commission (F.C.C