The Contribution of Non-Tropical Cyclone Vortices to the Rainfall of the Philippines

Weaker disturbances than tropical cyclones (TCs) such as tropical depressions and cold surges can significantly induce heavy rainfall and flooding events over the Philippines. However, the analysis of these disturbances including their rainfall contributions are often neglected in previous studies. As the first attempt to address this research gap, this study investigates the rainfall contribution of non-TC vortices over the Philippines from 1979 to 2020. Only those rainfall-producing non-TC vortices that formed and appeared within a 500-km radius from the Philippine coastline were examined in this study. A total of 7,686 non-TC vortex days (50% of the total days during the analysis period) were identified. The mean rainfall contribution of these non-TC vortices was found to be highest over the northeastern Mindanao Island (80–90% of the mean daily rainfall) and lowest over the central and western regions of Luzon Island (50–60%). Seasonal analysis of the occurrence frequency of these vortices shows that they are most frequent during the December–February (DJF) season. In this season, the rainfall contribution may increase to 50–80% of the mean daily rainfall over the whole country, while in the other seasons, the rainfall contribution may only increase to as much as 60%. Higher frequency of extreme rainfall days associated with these non-TC vortices were also found during the DJF season. The frequency of occurrence and percentage rainfall contribution of these non-TC vortices in relation to the different phases of the Boreal Summer Intraseasonal Oscillation (BSISO) during boreal summer (June–October) and the Madden–Julian Oscillation (MJO) during boreal winter (December–April) were also examined. Higher frequency and percentage rainfall contribution over the country were found during Phases 4–6 of both the BSISO and MJO, during which their respective active convections transition from the Maritime Continent to the western North Pacific

Influence of Boreal Summer Intraseasonal Oscillation on Rainfall Extremes in the Philippines

This study investigates the impact of the northward/northwestward propagating 30–60-day mode of the boreal summer intraseasonal oscillation (BSISO) on the extreme rainfall events in the Philippines during the June–September (JJAS) season from 1979 to 2018. The Philippines domain is divided into the three latitudinal regions: Luzon region (13°–22°N), Visayas region (10°–13°N), and Mindanao region (5°–10°N) to account for the regional differences in the timing of extreme rainfall events. The probability density functions of JJAS rainfall are skewed towards higher values relative to the non-BSISO days in BSISO Phases 6–8, Phases 5–7, and Phases 4–6 over the Luzon, Visayas, and Mindanao regions, respectively, during which the probability of extreme rainfall events at the 95th percentile increases by as much as 80% in some stations in these regions. Further analyses of the large-scale circulation features show that the increase (decrease) in the probability of extreme rainfall events is associated with enhanced moisture convergence (divergence) induced by the cyclonic (anticyclonic) circulation anomalies of the BSISO and appearance of multiple tropical cyclones. About 36% of the total extreme rainfall events over the Luzon region are associated with TCs during Phases 7–8. On the other hand, TCs contribute by no more than 24% in all phases over the Visayas and Mindanao regions, indicating less TC influence in these regions. This study is the first attempt to clarify the impact of the BSISO on the extreme rainfall events in the Philippines

The Effect of Urbanization on Temperature Indices in the Philippines

This paper presents a comprehensive analysis of the effect of urbanization on the surface air temperature (SAT) from 1951 to 2018 in the Philippines. The daily minimum temperature (Tmin) and daily maximum temperature (Tmax) records from 34 meteorological stations were used to derive extreme temperature indices. These stations were then classified as urban or rural based on satellite night-lights. The results showed a significant difference in the SAT trends between urban and rural stations, indicative of the effect of urbanization in the country. Larger and more significant warming trends were observed in indices related to Tmin than those related to Tmax. In particular, the effects of urbanization were significant in the annual index series of Tmin, diurnal temperature range, minimum Tmin, percentage of days when Tmin was less than the 10th percentile (TN10p), percentage of days when Tmin was greater than 90th percentile (TN90p), and the number of coldest nights. The effects of urbanization were not as clear on the index series of maximum Tmax (TXx), minimum Tmax (TXn), percentage of days when Tmax was less than 10th percentile (TX10p), and the number of hottest days. The effects of urbanization on the annual series of extreme temperature indices were statistically significant at the 95% confidence level, with the exception of Tmax, TXn, TXx, TX10p, and the number of hottest days. Further analysis revealed that the effect of urbanization was the greatest during the DJF (December–January–February) season. These findings serve as a baseline study that focuses on the countrywide effect of urbanization on SAT trends in the Philippines

A comparison of audio and visual English narratives on inference among college students

This study intended to compare which mode of presentation, whether audio or visual for English narratives, would aid in the comprehension, in the form of inference, of college students. One Hundred and Fifty (n = 150) participants, all were students of De La Salle university-Manila, were conveniently selected as participants for this research. Half of these participants underwent the auditory treatment, where they were asked to listen to the English narrative, while the remaining half went through the visual treatment, where they were asked to read the English narratives. Result show that those participants who had undergone the visual treatment scored significantly higher than those who had underwent the visual treatment. The data that was gathered in this research was analyzed using a t-Test for independent means

Diurnal variability of urban heat island intensity: A case study of Metro Manila, Philippines

We present the first analysis of the diurnal variability of the urban heat island (UHI)intensity in the metropolitan Manila (Metro Manila) in the Philippines. We used measurements from two automatic weather stations (AWSs) of the Philippine Atmospheric Geophysical and Astronomical Services Administration of the Department of Science and Technology (PAGASA-DOST) that operated in Metro Manila from 2014 to 2018. The highest averaged UHI intensity (UHImax) was 4.03°C, observed in the city of Manila (Port Area station) at 19:00 localtime (LT), whereas, in Quezon City (Science Garden station), UHImax was 3.02°C and was observed at 18:00 LT. The seasonal mean of the daily UHImax (daily maxima) occurred during the hot dry season (March–May), when lower normalized difference vegetation index (NDVI), relative humidity, and wind speed, as well as longer sunshine duration were observed. Results suggest that the influence of local characteristics on the locations of the station such as the building density, wind speed, and green spaces largely determined the UHI intensities in the study region

The Effects of Landfills on Rural Residential Property Values: Some Empirical Evidence

The question of whether solid waste landfills affect residential property values has long been a subject of debate. Past research has resulted in mixed conclusions. The current study examines six landfills, which differ in size, operating status, and history of contamination. The effect of each landfill is estimated by the use of multiple regression. In five of the landfills, no statistically significant evidence of an effect was found. In the remaining case, evidence of an effect was found, indicating that houses in close proximity to this landfill suffered an average loss of about six percent in value

FRP jacket assembly for retrofitting concrete structures

Most of the existing fibre-reinforced polymer (FRP) strengthening systems are wrapped directly to the structure creating a '2-material repair system', i.e. the existing structure and the FRP wrapping. Recently, a new type of FRP composite jacket with an innovative mechanical joining system for repair of existing structures has been developed. This repair system works by wrapping the prefabricated FRP jacket around the damaged structure and placing a grout infill between the jacket and the damaged structure producing a cylindrical confinement and creating a '3-material repair system'. The effective assembly of the components, the existing structure, the grout infill and the FRP jacket, is the key for the effective utilisation of this repair system. This paper reviews and evaluates the important parameters that affect the behaviour of structures repaired with the novel FRP jacket to ensure its structural integrity and efficiency

Experimental and numerical evaluations on the behaviour of structures repaired using prefabricated FRP composites jacket

Fibre reinforced polymer (FRP) composite jackets have become a popular option for repairing deteriorated structures due to the superior characteristics of composite materials in resisting corrosion and in providing a high strength but lightweight repair system. Recently, a novel prefabricated FRP composite jacket with an easy-fit and self-locking mechanical joining system was developed. This paper presents the experimental and numerical studies on the effectiveness of the FRP jacket in repairing reinforced concrete (RC) columns with simulated corrosion damage under uniaxial compressive loading. The experimental results showed that the jacket successfully stabilised and restored the axial strength capacity of the damaged concrete columns. Moreover, the results of the finite element (FE) analysis revealed that the joint of the jacket should be placed away from the damaged zone to minimise stress concentration and to effectively utilise the jacket as a repair system. Finally, a joint strength of at least 20 per cent of the hoop tensile strength of the jacket is effective in repairing damaged structures