Computational study of Klang Valley's urban climatology, and urbanisation of Putrajaya city, Malaysia

Urbanisation is associated with physical modifications of land surfaces and climate of a given area. Studies of urbanisation effect on urban climate of Klang Valley region is below par. This research aims to bridge the gap by using a coupled Weather Research and Forecasting (WRF) model with the NOAH Land Surface Model (NOAH) and Urban Canopy Model (UCM) – WRF/NOAH/UCM to investigate the urban climatology of Klang Valley and the urbanisation of Putrajaya over a decade. In addition, evaluation of the garden city concept adopted in the development of Putrajaya city is also conducted. The model is first validated against a network of meteorological observations in the region to determine its suitability for urban climate investigations. Climatological variables (near-surface temperature, relative humidity, and wind speed) along with land use and land cover (LULC) changes; planetary boundary layer height (PBLH), and urban heat/cool islands (UHI/UCI) of the area are also investigated. The model evaluation shows good performance over the region. LULC changes demonstrates strong influence in thermal climatology variations. A mean maximum UHI intensity of ~4.2 ºC was observed in the urban canopy-layer of the Klang Valley. Results reveal that urbanisation of Putrajaya leads to 2-m temperature increase at the rate of ~1.66 ºC per decade, with the area experiencing a mean UHI intensity of ~2.1 ºC per day. Other climatological variables vary accordingly with the urbanisation processes. Evaluation of the garden city concept indicates that the adopted concept causes a reduction in 2-m air temperature of the Putrajaya area, amounting to ~0.53 ºC per day; with vegetation contributing more (~0.39 ºC) to the daily reduction relative to water bodies (~0.14 ºC). Location of the city in the tropics accustomed with high intensity of daily solar radiation masked the cooling potentials of the concept to some extent

Small-scale postharvest practices among plantain farmers and traders: a potential for reducing losses in rivers state, Nigeria

High postharvest losses (PHLs) caused by poor postharvest management of perishable staple foods is a serious food security problem in Nigeria. Adoption of suitable postharvest management techniques is necessary to maintain produce quality and minimize avoidable losses by relevant stakeholders. The challenge is that most popular postharvest technologies are unsuitable for small scale farmers and traders who are a majority in the Nigerian food supply chains. This paper proposes the adoption of small-scale friendly postharvest techniques in the form of small-scale postharvest practices (SSPPs). To justify this proposal, the impact of SSPPs adoption on self-reported losses were investigated in Rivers State Nigeria. The factors influencing plantain farmers and traders intention to use SSPPs were also studied. Multistage and snowball sampling techniques were used to obtain data from farmers and traders, respectively. Data were obtained via face-to-face interviews using structured questionnaire. The data were analysed using descriptive statistics, correlation analysis, chi-square test of independence and multiple linear regression analyses. The results indicate that farmers adoption of SSPPs was negatively correlated with quantitative losses (r = - 0.142) and qualitative losses (r = - 0.412). Gender, education level, occupation, amount of produce harvested, and information access were significantly associated with farmers adoption of SSPPs. From the regression analysis, attitudes (β = 0.523, p < 0.05), awareness knowledge (β = 0.100, p < 0.05) and perceptions (β = 0.293, p < 0.05) of farmers significantly predicted their intention to use SSPPs. The regression model was significant (R2 = 0.552, F(3, 308 =126.264, p < 0.05)), with attitudes, awareness and perceptions explaining 55.2% of the variation in the dependent variable, intention. Based on the results, we recommend that plantain farmers and traders should integrate small scale postharvest practices in their operations because it will help them maintain produce shelf life and minimize avoidable losses. Policy makers, food security proponents and relevant institutions should take the necessary action by formulating tailored intervention programs that would facilitate adoption of SSPPs at farm and market levels. These recommendations will positively impact food security efforts in the country

Computational study of Klang Valley's urban climatology, and urbanisation of Putrajaya city, Malaysia

Urbanisation is associated with physical modifications of land surfaces and climate of a given area. Studies of urbanisation effect on urban climate of Klang Valley region is below par. This research aims to bridge the gap by using a coupled Weather Research and Forecasting (WRF) model with the NOAH Land Surface Model (NOAH) and Urban Canopy Model (UCM) – WRF/NOAH/UCM to investigate the urban climatology of Klang Valley and the urbanisation of Putrajaya over a decade. In addition, evaluation of the garden city concept adopted in the development of Putrajaya city is also conducted. The model is first validated against a network of meteorological observations in the region to determine its suitability for urban climate investigations. Climatological variables (near-surface temperature, relative humidity, and wind speed) along with land use and land cover (LULC) changes; planetary boundary layer height (PBLH), and urban heat/cool islands (UHI/UCI) of the area are also investigated. The model evaluation shows good performance over the region. LULC changes demonstrates strong influence in thermal climatology variations. A mean maximum UHI intensity of ~4.2 ºC was observed in the urban canopy-layer of the Klang Valley. Results reveal that urbanisation of Putrajaya leads to 2-m temperature increase at the rate of ~1.66 ºC per decade, with the area experiencing a mean UHI intensity of ~2.1 ºC per day. Other climatological variables vary accordingly with the urbanisation processes. Evaluation of the garden city concept indicates that the adopted concept causes a reduction in 2-m air temperature of the Putrajaya area, amounting to ~0.53 ºC per day; with vegetation contributing more (~0.39 ºC) to the daily reduction relative to water bodies (~0.14 ºC). Location of the city in the tropics accustomed with high intensity of daily solar radiation masked the cooling potentials of the concept to some extent

Effect of vegetation and waterbody on the garden city concept: an evaluation study using a newly developed city, Putrajaya, Malaysia

The garden city concept was adopted in the development of a new tropical city, Putrajaya, aimed at mitigating the effect of urban thermal modification associated with urbanisation, such as urban heat island (UHI). WRF/Noah/UCM coupled system was used to estimate the urban environment over the area and the individual thermal contributions of natural land use classes (vegetation and waterbody). A control experiment including all land use types describing the urban conditions of Putrajaya city agreed well with the observations in the region. A series of experiments was then conducted, in which vegetation and waterbody were successively replaced with an urban land use type, providing the basis for an assessment of their respective effect on urban thermal mitigation. Surface energy components, 2-m air temperature (T2m) and mixing ratio (Q2m), relative humidity (RH) and UHI intensity (UHII) showed variations for each land use class. Overall, an increase in urban surfaces caused a corresponding increase in the thermal conditions of the city. Conversely, waterbody and vegetation induced a daily reduction of 0.14 and 0.39 °C of T2m, respectively. RH, UHI and T2m also showed variations with urban fractions. A thermal reduction effect of vegetation is visible during mornings and nights, while that of water is minimally shown during daytime. However, during nights and mornings, canopy layer thermal conditions above waterbody remain relatively high, with a rather undesirable effect on the surrounding microclimate, because of its high heat capacity and thermal inertia

Upgrading of Napier grass pyrolytic oil using microporous and hierarchical mesoporous zeolites: products distribution, composition and reaction pathways

Reaction pathways in ex-situ catalytic upgrading of pyrolytic oil towards formation of specific products such as hydrocarbons are still not well established due to the presence of many different organic components in the raw pyrolytic oil. Currently, only a few studies are available in literature particularly with regards to application of hierarchical mesoporous zeolite in the refinement of sample pyrolytic oil. This study provides the first experimental investigation of ex-situ catalytic upgrading of pyrolytic oil derived from Napier grass using microporous and hierarchical mesoporous zeolites. Two hierarchical mesoporous zeolites were synthesized by desilication of microporous zeolite using 0.2 and 0.3 M solution of sodium hydroxide. Upgrading over microporous zeolite produced 16.0 wt% solid, 27.2 wt% organic phase and 23.9 wt% aqueous phase liquid while modified zeolites produced 21e42% less solid and 15e16% higher organic phase liquid. Higher degree of deoxygenation of pyrolytic oil was achieved with the modified zeolites. Analysis of organic phase collected after catalytic upgrading revealed high transformation of oxygenates into valuable products. Bulk zeolite produced cyclic olefins and polyaromatic hydrocarbons while mesoporous zeolites were selective toward cycloalkanes and alkylated monoaromatic production, with significant reduction in the production of polyaromatic hydrocarbon. Result of gas analysis showed that hierarchical mesoporous zeolite favoured decarboxylation and decarbonylation reactions compared to the parent zeolite, which promoted dehydration reaction. Mesoporous zeolite produced with 0.3 M sodium hydroxide solution was found to be the best-performing catalyst and its reusability was tested over four consecutive cycles. This study demonstrated that pyrolytic oil derived from Napier grass can be transformed into high-grade oil over hierarchical mesoporous zeolite

Recovery of clean energy precursors from Bambara groundnut waste via pyrolysis: Kinetics, products distribution and optimisation using response surface methodology

This study presents first comprehensive thermochemical analysis of Bambara groundnut shell. Pyrolysis characteristics was examined under non-isothermal degradation in nitrogen atmosphere at different heating rates (10, 15 and 20 �C/min) using single-step global model kinetic model. The single-step global model average apparent activation energy was found to be 142.64 ± 5.7 kJ/mol. Pyrolysis was conducted in a fixed bed reactor. Effects of pyrolysis temperature (450e750 �C), heating rate (20e50 �C/min) and nitrogen flow rate (5e25 L/min) were investigated collectively. The process variables were optimized using response surface methodology with central composite design. Optimum bio-oil yield of 36.49 wt% was recorded at 600 �C, 50 �C/min and 11 L/min. The bio-oil, bio-char and non-condensable gas collected were comprehensively characterised. Energy analysis of the products was also evaluated. This study revealed that Bambara groundnut shell, a residue from food crop, is a potential source of energy precursors for development of a sustainable bioenergy system and biomaterial

Spatial-temporal variations in surface ozone over Ushuaia and the Antarctic region: observations from in situ measurements, satellite data, and global models

The Antarctic continent is known to be an unpopulated region due to its extreme weather and climate conditions. However, the air quality over this continent can be affected by long-lived anthropogenic pollutants from the mainland. The Argentinian region of Ushuaia is often the main source area of accumulated hazardous gases over the Antarctic Peninsula. The main objective of this study is to report the first in situ observations yet known of surface ozone (O3) over Ushuaia, the Drake Passage, and Coastal Antarctic Peninsula (CAP) on board the RV Australis during the Malaysian Antarctic Scientific Expedition Cruise 2016 (MASEC’16). Hourly O3 data was measured continuously for 23 days using an EcoTech O3 analyzer. To understand more about the distribution of surface O3 over the Antarctic, we present the spatial and temporal of surface O3 of long-term data (2009–2015) obtained online from the World Meteorology Organization of World Data Centre for greenhouse gases (WMO WDCGG). Furthermore, surface O3 satellite data from the free online NOAA-Atmospheric Infrared Sounder (AIRS) database and online data assimilation from the European Centre for Medium-Range Weather Forecasts (ECMWF)-Monitoring Atmospheric Composition and Climate (MACC) were used. The data from both online products are compared to document the data sets and to give an indication of its quality towards in situ data. Finally, we used past carbon monoxide (CO) data as a proxy of surface O3 formation over Ushuaia and the Antarctic region. Our key findings were that the surface O3 mixing ratio during MASEC’16 increased from a minimum of 5 ppb to ~ 10–13 ppb approaching the Drake Passage and the Coastal Antarctic Peninsula (CAP) region. The anthropogenic and biogenic O3 precursors from Ushuaia and the marine region influenced the mixing ratio of surface O3 over the Drake Passage and CAP region. The past data from WDCGG showed that the annual O3 cycle has a maximum during the winter of 30 to 35 ppb between June and August and a minimum during the summer (January to February) of 10 to 20 ppb. The surface O3 mixing ratio during the summer was controlled by photochemical processes in the presence of sunlight, leading to the depletion process. During the winter, the photochemical production of surface O3 was more dominant. The NOAA-AIRS and ECMWF-MACC analysis agreed well with the MASEC’16 data but twice were higher during the expedition period. Finally, the CO past data showed the surface O3 mixing ratio was influenced by the CO mixing ratio over both the Ushuaia and Antarctic regions. Peak surface O3 and CO hourly mixing ratios reached up to ~ 38 ppb (O3) and ~ 500 ppb (CO) over Ushuaia. High CO over Ushuaia led to the depletion process of surface O3 over the region. Monthly CO mixing ratio over Antarctic (South Pole) were low, leading to the production of surface O3 over the Antarctic region