Saturation and parabolic effects of Langley Calibration at different altitude levels

The performance of the well-known Langley plot technique, used for the calibration of ground-based sunphotometers, has been investigated at three observatory sites of different altitudes. All solar measurements were collected using a portable LED-type sunphotometer programed to a constant measurement protocol to allow direct comparison between different days and sites. Our results show that evaluation on the correlation R-value and slope AOD-value alone is not robust enough to guarantee a good Langley plot. Statistical analysis on global, diffuse and direct component also fails to select a perfect Langley plot within a pool of data available. Instead, examination on the evolution of diffuse component and direct component against global component actually provides a good representation of the performance of Langley plot. Diurnal evolution of diffuse component and direct component was found closely matching to the global component in a similar increasing trend. Our results also highlighted two important effects that greatly govern the performance of Langley plot, which are saturation effect and parabolic effect. Saturation effect occurs for the state when little to no more signal increase can be legibly reflected on Langley plot. It is dominant in low airmass region where the change of airmass is relatively too small for the increase in signal detected by the sunphotometer. Parabolic effect is preceding effect of signal saturation and becomes severely erroneous when high air masses are included in Langley plot

Computer simulated versus observed NO2 and SO2 emitted from elevated point source complex

ISC-AERMOD dispersion model was used to predict air dispersion plumes from an diesel power plant complex. Emissions of NO2 and SO2 from stacks (5 numbers) and a waste oil incinerator were studied to evaluate the pollutant dispersion patterns and the risk of nearby population. Emission source strengths from the individual point sources were also evaluated to determine the sources of significant attribution. Results demonstrated the dispersions of pollutants were influenced by the dominant easterly wind direction with the cumulative maximum ground level concentrations of 589.86 μg/m3 (1 h TWA NO2) and 479.26 μg/m3 (1 h TWA SO2). Model performance evaluation by comparing the predicted concentrations with observed values at ten locations for the individual air pollutants using rigorous statistical procedures were found to be in good agreement. Among all the emission sources within the facility complex, SESB-Power (diesel power plant) had been singled out as a significant source of emission that contributed >85% of the total pollutants emitted

The regional biogenic emissions response to climate changes and ambient CO₂ in Southeast Asia

The emissions of isoprene from vegetation in the tropics have been regarded as one of the major sources of the global biogenic emission budget. As this emission is highly sensitive to temperature, one may expect significant changes to the emissions due to climate change. In this study, we explore the impact of regional climate change to the emissions of isoprene in Southeast Asia. The potential role of the combination of climate change and future atmospheric CO₂ concentration on isoprene emissions are also investigated. The latest generation of Hadley Centre regional climate modelling system, PRECIS (Providing Regional Climates for Impact Studies) was used to investigate the climate change in the region. The climate output dataset from the model was then used as input for the BVOC Emission Model, which was developed by Sheffield University and Lancaster University to estimate the emissions of biogenic volatile organic compounds. The projected temperature changes under the A₂ emission scenario was 2.5⁰C, which accounted an increase of 22% of isoprene emission from 29 to 37 TgC/yr if the CO₂ emission factor was excluded. Incorporation of higher concentration in future CO₂ emissions was found to offset the climate change impact on future emissions of isoprene in the region. With the CO₂ effects, the projected regional isoprene emissions in 2100 dropped from 28 to 25 TgC/yr. These results suggest that future emissions of isoprene in the region is largely buffered by a number of competing factors, which are certainly important to be considered in estimating the isoprene global budget. In a wider perspective, the anticipated high concentration of CO₂ in the future could lead to the disruption of the ozone, organic aerosol and methane formation through the competing influence with warmer climate on isoprene emissions from tropical vegetation

Combined climate impacts and vulnerability index on coastal ecosystems in prediction of future scenarios: extended sustainable indicator tool for adaptive strategy

Article Highlights Extension of methodology that integrates the climate variables (temperature, precipitation, and sea-level rise) with the changes of environment physical traits (CCVI) due to climate change impact were designed for coastal vulnerability assessment. The combined CCVI used ranked the relative risk by numerical vulnerability based on the physical properties for each of the marine coastal zone showing the potential hazard exacerbated by climate change and sea-level rise. Coastal areas of the Marudu Bay study area will experience a warmer atmosphere and increased total precipitation, and the sea level will rise under RCP 4.5 and RCP 8.5 at the regional measure. Thus, the study can be utilized as an extension to develop an effective adaptation strategy that is more targeted based and more focused type of the management plan

Upwelling event characteristics of chlorophyll-a concentration in the surface layer of Sabah waters

2532-2540Using satellite-based remote sensing data, the study analysed Chl-a levels throughout Sabah’s coastal waters and correlated the Chl-a levels with the corresponding SST levels for that time and region. It was found that upwelling in Sabah coastal waters was most strongly noted in Labuan during the Northeast Monsoon (NEM), which brings strong northeasterly winds to Sabah’s west and north coast. The strong winds can be cited as the main source of increased upwelling as SST levels did not sufficiently change to suggest a strong relationship between SST and Chl-a levels

Carbon monoxide levels along roadway

This paper predicts and compares the carbon monoxide (CO) concentration levels along Sembulan Road for years 2004 and 2014 using CAL3QHC air dispersion model at two major locations, i.e., at Sembulan Roundabout and Sutera Harbour Intersection, Kota Kinabalu, Sabah, Malaysia. The CO concentration "hot-spots" were also identified at Sutera Harbour Intersection, and the highest maximum 1-hr average ground level concentrations of CO modeled for Kpg. Air Sembulan located in the northeast of idling road was 9.33 ppm for year 2004. This study showed that there would be no extreme changes in CO concentration trends for year 2014 although a substantial increase in the number of vehicles is assumed to affect the level of CO concentrations. It was also found that the CO levels would be well below the Malaysian Ambient Air Quality Guidelines of 30 ppm for 1-hour Time-Weighted Average (TWA). Comparisons between the modeled and observed outputs using quantitative data analysis technique and statistical methods indicated that the CAL3QHC predicted results correlated well with measured data. It was predicted that receptors located near to the major intersection, in the long-term would be potentially exposed to relatively higher CO levels

Computer simulated versus observed NO2 and SO2 emitted from elevated point source complex

ISC-AERMOD dispersion model was used to predict air dispersion plumes from an diesel power plant complex. Emissions of NO2 and SO2 from stacks (5 numbers) and a waste oil incinerator were studied to evaluate the pollutant dispersion patterns and the risk of nearby population. Emission source strengths from the individual point sources were also evaluated to determine the sources of significant attribution. Results demonstrated the dispersions of pollutants were influenced by the dominant easterly wind direction with the cumulative maximum ground level concentrations of 589.86 μg/m3 (1 h TWA NO2) and 479.26 μg/m3 (1 h TWA SO2). Model performance evaluation by comparing the predicted concentrations with observed values at ten locations for the individual air pollutants using rigorous statistical procedures were found to be in good agreement. Among all the emission sources within the facility complex, SESB-Power (diesel power plant) had been singled out as a significant source of emission that contributed > 85% of the total pollutants emitted