Kehinde ogunjobi - Academia.edu (original) (raw)

Papers by Kehinde ogunjobi

The impacts of global warming on rainfall in West Africa were examined using a numerical framewor... more The impacts of global warming on rainfall in West Africa were examined using a numerical framework for 5 monsoon years (2001, 2007, 2008, 2010, and 2011). Rainfall characteristics over the three climatic zones, Guinea coast, Savannah, and Sahel, were analyzed. The potential changes associated with global warming were assessed by the pseudo-global warming (PGW) downscaling method. Multiple PGW runs were conducted using climate perturbation from the 40member ensemble of the Community Earth System Model version 1 (CESM1) coupled with Community Atmospheric Model version 5.2 (CAM5.2) component large ensemble project. The model output was compared with Tropical Rainfall Measuring Mission and Global Precipitation Climatology Project rainfall alongside surface temperature from the European Center for Medium-Range Weather Forecast Reanalysis. Results show that the estimated rainfall amount from the future climate in the 2070s increases slightly compared with the current climate. The total rainfall amount simulated for the current climate is 16% and 63% less than that of the PGW runs and observations, respectively. Also found is an increase (decrease) in heavy (light and moderate) rainfall amount in the PGW runs. These results are, however, contingent on the global circulation model (GCM), which provides the boundary conditions of the regional climate model. CESM1.0-CAM5.2, the GCM employed in this study, tends to provide a greater surface temperature change of about 4 C. This projected temperature change consequently caused the increase in the simulated precipitation in the PGW experiments, thus highlighting the advantage of using the PGW method to estimate the likely difference between the present and future climate with reduced large-scale model differences and computational resources. The findings of this study are, however, useful to inform decision-making in climate-related activities and guide the design of climate change adaptation projects for the West African region.

Biomass Burning (BB) aerosol has attracted considerable attention due to its detrimental effects ... more Biomass Burning (BB) aerosol has attracted considerable attention due to its detrimental effects on climate through its radiative properties. In Africa, fire patterns are anticorrelated with the southward-northward movement of the intertropical convergence zone (ITCZ). Each year between June and September, BB occurs in the southern hemisphere of Africa, and aerosols are carried westward by the African Easterly Jet (AEJ) and advected at an altitude of between 2 and 4 km. Observations made during a field campaign of Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa (DACCIWA) (Knippertz et al., Bull Am Meteorol Soc 96:1451-1460, 2015) during the West African Monsoon (WAM) of June-July 2016 have revealed large quantities of BB aerosols in the Planetary Boundary Layer (PBL) over southern West Africa (SWA). This chapter examines the effects of the long-range transport of BB aerosols on the climate over SWA by means of a modeling study, and proposes several adaptation and mitigation strategies for policy makers regarding this phenomenon. A high-resolution regional climate model, known as the Consortium for Small-scale Modelling-Aerosols and Reactive Traces (COSMO-ART) gases, was used to conduct two set of experiments, with and without BB emissions, to quantify their impacts on the SWA atmosphere. Results revealed a reduction in surface shortwave (SW) radiation of up to about 6.5 W m À2 and an 11% increase of Cloud Droplets Number Concentration (CDNC) over the SWA domain. Also, an increase of 12.45% in Particulate Matter (PM 25) surface concentration was observed in Abidjan (9.75 μg m À3), Accra (10.7 μg m À3), Cotonou (10.7 μg m À3), and Lagos (8 μg m À3), while the carbon monoxide (CO) mixing ratio increased by 90 ppb in Abidjan and Accra due to BB. Moreover, BB aerosols were found to contribute to a

African Handbook of Climate Change Adaptation

Environmental Research Letters

Atmospheric Chemistry and Physics

Atmospheric Chemistry and Physics Discussions

Between June and September large amounts of biomass burning aerosol are released into the atmosph... more Between June and September large amounts of biomass burning aerosol are released into the atmosphere from agricultural fires in Central and southern Africa. Recent studies have suggested that this plume is carried westward over the Atlantic Ocean at altitudes between 2 and 4 km and then northward with the monsoon flow at low levels to increase the atmospheric aerosol load over coastal cities in southern West Africa (SWA), thereby exacerbating air pollution problems. However, the processes by which these fire emissions are transported into the planetary boundary layer are still unclear. One potential factor is the large-scale subsidence related to the southern branch of the monsoon Hadley cell over the tropical Atlantic. Here we use convectionpermitting model simulations with COSMO-ART to investigate for the first time to what extent mixing related to cloud venting contributes to the downward transport of the biomass burning plume. Based on a monthly climatology, model simulations compare satisfactory with wind fields from reanalysis data, cloud observations, and satellite retrieved CO mixing ratio. For a case study on 02 July 2016, modelled clouds and rainfall show overall good agreement with Spinning Enhanced Visible and InfraRed Imager (SEVIRI) cloud products and Global Precipitation Measurement Integrated Multi-satellite Retrievals (GPM-IMERG) rainfall estimates. However, there is a tendency for the model to produce too much clouds and rainfall over the Gulf of Guinea. Looking into the CO dispersion, used as an indicator for the biomass burning plume, we identified individual

Theoretical and Applied Climatology

A 2-month (August-September) regime of the year 2007 West African monsoon (WAM) was simulated wit... more A 2-month (August-September) regime of the year 2007 West African monsoon (WAM) was simulated with 27 physics combinations using the Weather Research and Forecasting model at 20-km horizontal grid. The objective is to examine WAM sensitivity to parameterization of microphysical, convective, and boundary layer processes for long-term simulation. The model precipitation was evaluated against the TRMM, CMORPH, and GPCP satellite rainfall products. The surface temperature was compared against the ERA-Interim, NCEP, MERRA, and global surface air temperature, an ensemble of the three reanalysis datasets. Model skill score (MSS) computed from a synthesis of the normalized correlation coefficient, mean bias, and mean absolute error was used to rank the model performance. Results show the model adequately simulates the diurnal cycles of surface temperature than precipitation, as well as the westward propagation of intense precipitation associated with the African easterly waves. The new Grell-Freitas (nGF) cumulus parameterization scheme (CPS) outperforms its predecessor especially when combined with the Mellor-Yamada-Nakanishi-Niino 2.5 (MYNN) planetary boundary layer scheme. The new simplified Arakawa-Schubert (nSAS) and Tiedtke CPSs produced better simulation of precipitation and surface temperature, respectively. The simulation of observed peak of diurnal precipitation in nSAS and nGF highlights success made towards a more realistic representation of convective processes by the schemes. Goddard microphysics and MYNN performed better for both variables. Based on the MSS, some relatively good and poorly performing combinations for precipitation and surface temperature were identified. The optimal combinations are however not separated in a statistically significant way and, thus, could be used for longterm simulation of WAM.

OALib

This study used daily observation data obtained from the Nigerian Meteorological Agency (NiMet) t... more This study used daily observation data obtained from the Nigerian Meteorological Agency (NiMet) to investigate the temperature trend of Nigeria from 1981-2015. The data were homogenised using the Quantile Matching (QM) method and Quality Controlled. The data have been transformed into three sets of data with different periods: daily, monthly and yearly. The datasets (daily, monthly and yearly) were checked for autocorrelation and if they were found auto correlated, the Modified Mann Kendall (MMK) and the Pre-Whitening (PW) methods were used and compared, if not the normal Mann Kendall (MK) test was applied. The results showed for the different methods, variations in the trend from one station to another and for the minimum and maximum temperature. These variations were observed in the different methods and data screening the performance of each of the methods in the datasets. The general trend was found to be increasing. The variations in the temperature increase the Diurnal Temperature Range (DTR) that impact human health and increase the probability of occurrence of extreme events.

Journal of Fundamentals of Renewable Energy and Applications, 2017

International Journal of Climatology, 2016

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2016

This study employs Landsat ETM+ satellite imagery to access the inter-seasonal variations of Surf... more This study employs Landsat ETM+ satellite imagery to access the inter-seasonal variations of Surface Temperature and Vegetation cover in Ondo State in 2013. Also, air temperature data for year 2013 acquired from 3 synoptic meteorological stations across the state were analyzed. The Single-channel Algorithm was used to extract the surface temperature maps from the digital number embedded within the individual pixel. To understand the spatio-temporal distribution of LST and vegetation across the various landuse types, 200 sample points were randomly chosen, so that each land-use covers 40 points. Imagery for the raining season where unavailable because of the intense cloud cover. Result showed that the lowest air temperature of 20.9°C was in January, while the highest air temperature of 34°C occurred in January and March. There was a significant shift in the vegetation greenness over Ondo State, as average NDVI tend to increase from a weak positive value (0.189) to a moderate ...

International Journal of Sustainable Agricultural Research, 2015

Assessment of climate variability at local level has enormous advantage in Ethiopia, where the dr... more Assessment of climate variability at local level has enormous advantage in Ethiopia, where the driver of the economy is agriculture. This study was conducted to analysis rainfall and temperature variability to guide sorghum production in Miesso. Daily climate data was obtained from the National Meteorological Service Agency of Ethiopia (NMA). Temporal rainfall variability was assessed through the timing of onset date, end date, length of growing season and dry spell length using INSTAT climate guide. Temperature variability was examined in terms of pattern, trend and probability of exceedence. The long-term annual rainfall showed high variability from year to year with 25% coefficient of variation. Seasonally, the MAM total rainfall showed high variability than the JJAS total rainfall at Miesso. Rainfall onset date and length of growing season were highly variable. Higher minimum temperature values (>16 o C) are observed from April to August whereas maximum temperature reaches its lowest level in December, but increase again to maximum in June and start to decline as of July. The minimum and maximum temperatures showed an increasing trend both seasonally and annually. To avert the risks of rainfall and temperature variability the use of seasonal climate outlook is recommended for adjusting farm operations and farming system decisions in Miesso areas.

Advances in Meteorology, 2015

This study evaluates the ability of three Regional Climate Models (RCMs) used in Coordinated Regi... more This study evaluates the ability of three Regional Climate Models (RCMs) used in Coordinated Regional Climate Downscaling Experiment (CORDEX) to simulate the characteristics of rainfall pattern during the West Africa Summer Monsoon from 1998 to 2008. The seasonal climatology, annual rainfall cycles, and wind fields of the RCMs output were assessed over three homogenous subregions and validated using precipitation data from eighty-one (81) ground observation stations and TRMM satellite data. Furthermore, the ability of the RCMs to simulate response to El Nino and La Nina events was assessed. Results show that two of the RCMs (RCA and REMO) simulated the main features of the rainfall climatology and associated dynamics over the three subregions (Guinea Coast, Savannah, and Sahel) of West Africa. The RCMs also capture the African Easterly Jet (AEJ) and Tropical Easterly Jet (TEJ) with little variations in position and intensity. Analysis shows significant biases in individual models de...

Theoretical and Applied Climatology, 2015

Remote Sensing in Atmospheric Pollution Monitoring and Control, 2004

An integrated system approach has been adopted at the Advanced Environment Monitoring Research Ce... more An integrated system approach has been adopted at the Advanced Environment Monitoring Research Center (ADEMRC), Kwangju Institute Science and Technology (KJIST), Korea for the effective monitoring of atmospheric environment utilizing various optical remote sensing methods. A multi-channel LIDAR system has been used since December 2002 to monitor the vertical profile of atmospheric aerosol. Vertical profiles of extinction coefficient, depolarization ratio,

Environment, Development and Sustainability, 2014

This study examines households' perception and livelihood vulnerability to climate change in a co... more This study examines households' perception and livelihood vulnerability to climate change in a coastal area of Akwa Ibom State, Nigeria. It employed multistage sampling procedure, selected a total of 101 households from three coastal communities in Ibeno local government area of Akwa Ibom State, Nigeria and obtained primary data on several indicators through interviews guided by a structured questionnaire. From the data obtained, the study examined households' perception and developed a livelihood vulnerability index (LVI) to assess livelihood vulnerability. The result showed that households in the study area generally perceive that all the climate variables considered in the study, especially timing and length of the average rainy season, have changed over time. These are in line with meteorological data obtained from the Nigerian Meteorological Agency. In addition, the LVI shows that households are vulnerable to changes in climate variables. Households in the study area are striving to adapt to these changes but facing many challenges of which lack of adequate finance is the most important. Although these challenges are multifarious, they can be reduced through adequate support of government and non-governmental organizations. Consequently, policy recommendations are discussed.