Justin Sentian

Ground-based aerosol optical depth measurement using sunphotometers

Introduction.- Ground-Based Aerosol Optical Depth Measurement.- Near-Sea-Level Langley Calibration Algorithm.- Implementation of Perez-Dumortier Calibration Algorithm.- Conclusion.

COMPARISON OF GEV AND GUMBLE’S DISTRIBUTION FOR DEVELOPMENT OF INTENSITY DURATION FREQUENCY CURVE FOR FLOOD PRONE AREA IN SABAH

Rainfall data has a significant role in hydrological design which is, it’s produce the intensity duration frequency curve. IDF curve gives critical information that needed in the design of water management infrastructure, it gives information by showing the mathematical relation of rainfall intensity, recurrence interval of the storm and duration of storm. This paper aims to compares and develop IDF curve using two frequency distribution which is generalized extreme value distribution (GEV) and Gumbel distribution (EV1). Then, the best fit distribution for flood-prone area in Sabah will be choose and determined from the two-mentioned distribution. The goodness of fit test that used to determine the best distribution is chi-square test, it works by determining the differences between observe data value from Weibull formula and the estimated values from GEV and Gumbel’s distribution method. After that the chi-square value for GEV and Gumbel is compared to the critical value from chi-square table at significant level of 5%. From the Chi-square test, it is concluded that Gumbel’s (chi square value Tandek:0.47952, patiu:1.0531, babagon: 1.026931, Ulu Moyog:0.382415) shows a better fit distribution compared to GEV distribution (chi square value Tandek:59.7598, patiu:16.5746, babagon: 3.3555347, Ulu Moyog:22.1315)

Potential of Solar Energy in Kota Kinabalu, Sabah: An Estimate Using a Photovoltaic System Model

Solar energy is becoming popular as an alternative renewable energy to conventional energy source, particularly in the tropics, where duration and intensity of solar radiation are longer. This study is to assess the potential of solar energy generated from solar for Kota Kinabalu, a rapidly developing city in the State of Sabah, Malaysia. A year data of solar radiation was obtained using pyranometer, which was located at Universiti Malaysia Sabah (6.0367° N, 116.1186° E). It was concluded that the annual average solar radiation received in Kota Kinabalu was 182 W/m2. In estimating the potential energy generated from solar for Kota Kinabalu city area, a photovoltaic (PV) system model was used. The results showed that, Kota Kinabalu is estimated to produce 29,794 kWh/m2 of electricity from the solar radiation received in a year. This is equivalent to 0.014 MW of electricity produced just by using one solar panel. Considering the power demand in Sabah by 2020 is 1,331 MW, this model showed that the solar energy can contribute around 4% of energy for power demand, with 1 MW capacity of the PV system. 1 MW of PV system installation will require about 0.0328% from total area of the city. This assessment could suggest that, exploration for solar power energy as an alternative source of renewable energy in the city can be optimised and designed to attain significant higher percentage of contribution to the energy demand in the state.

Implementation of perez-dumortier calibration algorithm

To avoid the unnecessary needs to travel to high altitude for sunphotometers calibration, Perez-Dumotier calibration algorithm has been used as an objective means to select the right intensity data so that the calibration can be performed at any altitude levels. The governing theory of the algorithm was discussed in the previous chapter. This chapter presents information on how to implement the Perez-Dumotier calibration algorithm using actual field measurement. The implementation of the filtration procedure in step-by-step is discussed to render better framework of the proposed calibration algorithm. The aerosol retrieval inversion uses the extraterrestrial constant obtained from the final Langley plot to calculate retrieved AOD. The implementation example uses irradiance-matched technique by i-SMARTS radiative transfer code to derive corresponding reference AOD for validation purposes. The reliability of the technique was substantiated by radiative closure experiment to verify the promising direct solar irradiance to accurately derive the reference AOD values.

Ground-Based Aerosol Optical Depth Measurements

This chapter presents a detailed overview on the theory of aerosol optical depth retrieval with the emphasis on ground-based sunphotometry technique. To further discuss on the calibration issue as mentioned previously, this overview also includes the principle of the oldest passive ground-based calibration method, Langley calibration to provide an insight on the working mechanism of the method. The final part in this chapter compiles the previous existing Langley calibration method in a chronological sequence to render a better comprehension on its development from the past to present time.

Seasonal Variation of Aliphatic Hydrocarbons in Atmospheric Environment of Kota Kinabalu, Sabah

Suspended particulate matters of atmospheric samples were collected and analyzed for aliphatic hydrocarbons from Kota Kinabalu, Sabah, on 2011. Samples were extracted using Soxhlet apparatus, run in two-step column chromatography and the final fraction was spiked into gas chromatography-mass spectrometry. An authentic n-alkane standard (10 mg/l) ranging from C10 to C40 was used as external standard for quantification and qualification of target compounds in the samples. The result showed that the dry season had the highest concentration of atmospheric n-alkane of around 151 ng/m3/d comparing to a minimum of 89 ng/m3/d in the wet season. The results indicate that the amount of high molecular weight n-alkane increases during dry season while wet season had the peak range of lower molecular weight. The carbon preference index value indicates an important contribution from petroleum and diesel materials in the study area. Presence of unresolved complex mixture in most of the samples reveals vehicular exhaust output involvement. Natural hydrocarbons as the minor contributor in the samples were observed during dry season due to the availability of plant material and dust in the atmosphere. It seems that frequent tropical rain clears the atmosphere from dust, burned particulate matters and plant residues during wet season while less rain in dry season provides availability of particulate matters in the atmosphere.

Near-Sea-Level Langley Calibration Algorithm

As compared to other methods, measurement of aerosol optical depth (AOD) using sunphotometers offer several advantages. However, it suffers a drawback as calibration of the instrument required to be performed at high altitude due to temporal drifts in the atmospheric condition during the calibration. To solve this, a new Langley calibration algorithm has been designed for AOD measurement using spectroradiometer instrument. The key advantages of the proposed algorithm are its objectivity, computational efficiency and the ability to detect short intervals of cloud transits. It avoids travelling to high altitude mountain that the conventional calibration procedure always practiced for frequent calibration. Most importantly, neither it requires priori knowledge of the instrument calibration nor a collocated calibrated instrument for nominal calibration transfer to perform the cloud-screening procedure.