Tropical Climatic Conditions Research Articles

Impact of Room Colors and Construction Materials on Temperature Distribution in Tropical Climate: An Experimental Study in Nonthaburi, Thailand

This experimental research investigates the thermal performance of different room colors and construction materials under Thailand's tropical climate conditions. The study was conducted over a six-month period in Nonthaburi, Thailand, examining temperature variations across multiple room configurations. Using precision monitoring equipment, we analyzed how traditional Thai building materials and various wall colors affect indoor temperature distribution. The research encompassed both modern and traditional Thai construction materials, including concrete, brick, traditional teak wood, and bamboo, combined with different wall colors (white, cream, terra cotta, and dark blue). Results demonstrated that rooms with traditional materials like teak wood maintained lower average temperatures (by 3.2°C) compared to modern concrete structures, while light-colored walls showed up to 4.1°C temperature difference compared to darker colors during peak sunshine hours.

Global Spatial Projections of Forest Soil Respiration and Associated Uncertainties

The accurate prediction of global forest soil respiration (Rs) is critical for climate change research. Rs consists of autotrophic (Ra) and heterotrophic (Rh) respiration, which respond differently to environmental factors. Predicting Rs as a single flux can be biased; therefore, Ra and Rh should be predicted separately to improve prediction accuracy. In this study, we used the SRDB_V5 database and the random forest model to analyze the uncertainty in predicting Rs using a single global model (SGM) and Ra/Rh using a specific categorical model (SCM) and predicted the spatial dynamics of the distribution pattern of forest Ra, Rh, and Rs in the future under the two different climate patterns. The results show that Rs is higher under tropical and inland climatic conditions, while Rh fluctuates less than Ra and Rs. In addition, the SCM predictions better capture key environmental factors and are more consistent with actual data. In the SSP585 (high emissions) scenario, Rs is projected to increase by 19.59 percent, while in the SSP126 (low emissions) scenario, Rs increases by only 3.76 percent over 80 years, which underlines the need for SCM in future projections.

Agri-solar water pumping design, energy, and environmental analysis: A comprehensive study in tropical humid climate

Agrivoltaics is an innovative approach where solar energy, water, land and biodiversity are integrated into the same area to maximize resource utilization for sustainable development, also known as Agrivoltaism. The combination of solar water pumping and agri-solar has led to the development of a new generation of irrigation systems that are highly sustainable and efficient. Agri-solar water pumping can irrigate crops, feed livestock, clean solar modules, cool the PV system, generate energy, store water, and provide community drinking water. This paper addresses the basic design and capacity requirements of solar water pumping systems for irrigating a 0.5-ha Agrivoltaics system in Kuala Lumpur. The SISIFO tool has been used to simulate the Agri-solar water pumping performance for tropical humid climatic conditions. The various parameters like site details, climate data, type of PV modules, DC pump -motor and converters are used as input data to evaluate the energy yield parameters (output energy in DC and AC form), hydraulic parameters (volume of water pumped), loss parameters (capture and system losses) and efficiency parameters (performance of the system). Lettuce was chosen as it is fast growing with good yield per hectare. Based on the result, a detailed analysis of the agrivoltaic lettuce plant is performed. A detailed analysis of the solar resource assessment, system design, Key performance indicators, loss analysis and environmental analysis of the Agri-solar water pumping has been carried out. Considering their specific climatic conditions, this can significantly assist policymakers in selecting the optimal solar pumping station for agrivoltaic plants. The importance of considering various factors when choosing a solar pumping station for agrivoltaics is also highlighted.

Analysis of Main Components of Five Mulberry Varieties in Tropics.

Mulberries (Morus alba L.) contain rich and beneficial nutrients for human health. However, as a temperate adaptive species, high-temperature and high-humidity climate conditions may alter the main nutritional value of mulberries after their intended arrival in tropical regions, which has not yet been reported on. In this study, we analyzed the differences in morphology, sugars, organic acids, free amino acids, and aroma contents of five mulberry varieties in the tropics between two harvesting periods. The results show that the full-ripe fruits of M. laevigata W (TLM) have the longest fruit length (83.67 mm) and highest brix (25.90); meanwhile, full-ripe fruits of M. atropurpurea R (D10M) have the longest fruit transverse stem (20.00 ± 0.577 mm) and single-fruit weight (9.63 ± 0.033 g). Fructose, glucose, and sucrose were the main sugars, and oxalic acid, quinic acid, malic acid, and citric acid were the main organic acids in all varieties; in addition, the sucrose content in mature fruits of M. laevigata W. (BLM) and M. alba L. BZZ (BZM) was significantly higher than other sugars. Twenty free amino acids were detected in all five varieties and asparagine was the main free amino acid. A total of 100 volatile compounds were identified, including 31 esters, 20 aldehydes, 14 hydrocarbons, 11 alcohols, 10 acids, 6 ketones, and 8 others. Although the main components of five mulberry full-ripe fruits were significantly higher than the green-ripe fruits, gamma-amino butyric acid and a few other components were otherwise. The research results show that the tropical climate conditions could increase the main nutritional components of mulberries, but the specific molecular regulatory mechanisms need to be further analyzed.

Land Use affects the Soil Aggregation Pattern during Restoration of Degraded Land under Tropical Dry Climate

Soil aggregate formation and stability are crucial in safeguarding soil carbon pools, as they form the basic unit of soil structure in terrestrial ecosystems. The impact of different land uses on soil aggregation pattern has widely been studied but is limited under tropical dry climate conditions. This study aimed to determine the soil aggregation pattern at two soil depths (0-15 cm and 15-30cm) in three different plantations (Peltophorum pterocarpum, Eucalyptus globulus, and Acacia nilotica) established in degraded land under tropical dry climate. The soil aggregates were categorized into microaggregate, mesoaggregate and macroaggregate based on their size fractions which were determined by the wet sieving method. The percent of macroaggregate, mesoaggregate, and microaggregate fractions at 0-15 cm depth ranged from 62.2 – 82.6%, 31.6 – 36.7%, and 1.1 – 4.9 % respectively whereas at 15-30 cm depth, it ranged from 69.7 - 81.7%, 17.1 - 31.6%, and 1.2 - 2.8%. The mean weight diameter values at 0-15 cm and 15-30 cm soil depth ranged from 2.27-3.37mm and 2.85-3.35 mm respectively. The higher percentage of macroaggregate fractions in Peltophorum pterocarpum plantation compared to Eucalyptus globulus, and Acacia nilotica plantations indicated that the Peltophorum pterocarpum plantation has slightly more potential to improve aggregate formation and soil structure in the degraded lands under tropical dry climate. In addition, appropriate land use practices can increase soil aggregate stability in the study area.

Pattern of flower and fruit abscision and fruit growth of hass avocado under tropical conditions

Research elucidating abscission processes in fruits of Hass avocados has been conducted in production areas in the subtropics, but there are few studies under tropical climate conditions that can serve as a starting point to guide suitable management practices. In a seven-year-old commercial orchard of Hass avocados, grafted onto native rootstocks (Antillean rootstocks), 20 trees were evaluated. A weather station installed on-site monitored the climate of the location. The pattern of fruit growth and development, flower and fruit abscission, and yield variables were characterized. More than 145,000 and 270,000 flowers abscised per tree were recorded, with final fruit sets of 0.1 ± 0.009% and 0.19 ± 0.04% in the first and second crop years, respectively. Fruit growth followed a sigmoid curve with no differences in growing degree-days until the time of harvest. Additionally, the alternate bearing behavior of Hass avocado was confirmed with an average yield of 24.3 ± 4.5 kg/tree and 93.3 ± 9.5 kg/tree for the first and second crop years, respectively, finding an average alternate bearing index of 0.74 ± 0.06.

Degradation of Emamectin Benzoate in the Aquaculture Pond Environment under Tropical Climatic Condition

Emamectin Benzoate (EMB), is an anti-parasitic drug, commonly used in aquaculture for prevention and control of parasitic infestations. The drug enters the environment through uneaten feed and faeces, ultimately accumulating in aquaculture pond sediment. Present study reports the influence of abiotic factors like, sunlight exposure (2,454 to 117,500 lux), pH, salinity and soil texture on the degradation of EMB in aquaculture pond water and sediment as per Organization for Economic Cooperation and Development (OECD). Results showed that the degradation of EMB in both water and sediment followed first-order kinetics, resulting in half-life of 5.6 days in water and 12.4 days in sediment when exposed to natural sunlight. Higher degradation of EMB was observed under alkaline conditions (pH 8.5) and at lower salinity (0.5ppt). EMB degradation is accelerated in loamy sand soil when exposed to sunlight. Results of the study suggest that in countries like India, where ample sunlight exposure is prevalent throughout the year, EMB degradation in aquaculture pond environment occurs at a rapid pace reducing the risk of accumulation in water or sediment.

Assessing the performance of a monocrystalline solar panel under different tropical climatic conditions in Cameroon using artificial neural network

To implement the European Union (EU)-Africa Green Energy Initiative in Cameroon to boost the renewable energy sector, we model the performance of a 500 W monocrystalline solar panel in major cities of Cameroon located in different climatic zones to select the best location for the installation of a solar farm. We also evaluate the contribution of seasonal and weather variability to the amount and stability of power generated by the panel using the artificial neural network (ANN). The ANN model was used to train and test the ERA5 hourly data for Bamenda. The model was then used to estimate Photovoltaic (PV) output in Douala, Yaounde, Ngaoundere, Garoua, and Maroua with a mean absolute error of 4.109 × 10−5, 4.699 × 10−5, 3.563 × 10−5, 3.106 × 10−5, and 3.083 × 10−5 kW, respectively. The results show that the ANN can capture the influence of weather variability on the generated output power. Cloud cover and rainfall are found to negatively affect the amount and stability of generated power in the lower latitude cities of Douala and Yaounde compared to the northern cities, with these effects being stronger in the rainy season than in the dry season. Garoua followed by Maroua are proving to be the best locations for installing a solar park in terms of the amount and stability of electricity generated throughout the year. The Cameroonian government, its EU partners, and other stakeholders involved in the development of solar energy in the country will be able to use the results of this study for better decision-making.

Assessment of river ecological status in the French West Indies based on diatom flora

The Water Framework Directive (WFD) requires member states to routinely assess the river ecological status using community-based indices. However, there is still a lack of published WFD-compliant methods for the French West Indies, especially using diatom-based indices. Martinique and Guadeloupe exhibit diverse landscapes shaped by their complex geological history and tropical climatic conditions. These strong particularities make the existing indices developed for the European mainland unusable. Based on diatom sampling from to 2013 (607 samples) and through multivariate analyses, we developed the Indice Diatomique des Antilles (IDA). We first identified the key abiotic factors influencing diatom communities on both islands, and then characterized taxon sensitivity by considering their presence probability along a pressure gradient.. The index was based on the presence and relative abundance of these taxa in each sample. The last step consisted of using new data from the 2014–2022 sampling surveys (457 samples) as a validation dataset to verify IDA accuracy. Our results suggest that the IDA methodology is well designed to assess the ecological status of rivers in the West Indies.

Selection of tropical plants for an extensive green roof with abilities of thermal performance, energy conservation, and greenhouse gas mitigation

The development of green roofs to mitigate urban heat island effect is critical for conserving energy and reducing carbon footprint. This study evaluated the thermal performance of an extensive green roof design compared with a conventional roof and assessed the suitability of thirty-two plants for low-maintenance green roofs in a tropical area. Experiments were carried out in four phases, covering the tropical climatic conditions from June 2016 to December 2017. The results indicate that a green roof temperature was significantly lower than that of a conventional roof by 12 °C. This led to an 84 % reduction in heat transfer through the building, potentially leading to a decrease in electricity consumption by 0.20 kWh/m2/8 h and saving electricity costs by 0.019 USD/m2/8 h, achieved through a reduction in the cooling load on air conditioners. The highest carbon dioxide removal achieved in this study was 3.01 kgCO2/m2, with an effective mitigation of greenhouse gases by 28.46 kgCO2eq/m2/year. The top three plant species recommended for a low-maintenance green roof are Dracaena cochinchinensis, Santisukia kerrii, and Dracaena kaweesakii. The plant characteristics for low-maintenance green roofs in tropical climates include drought and extreme weather tolerance, disease and insect resistance, short and spreading roots, succulent leaves with ability to store water, low water requirements, slow growth rate, easy availability locally and affordability, thriving in low-nutrient conditions, and a high evapotranspiration rate. In applicable contexts, green roofs designed with suitable tropical plants could potentially enhance urban environments and contribute to achieving low-carbon and environmental sustainability.

MODELLING STUDY ON CENTRAL COURTYARD SHADING STRATEGY IN TROPICAL CLIMATE REGION MALAYSIA

A courtyard is an open multi-functional space and an effective daylight passive design strategy in a building. However, to have a courtyard in a tropical country, it had to deal with the issue of visual discomfort, which requires some consideration in adaptation to the climate condition. These visual comfort issues include inconsistent light distribution, inappropriate illuminance levels, glare, and a lack of shaded areas. The focus of this research paper is to address the solution of shading strategies towards the visual discomfort issues associated with courtyard spaces. The solution is done by modelling study method on courtyard ratios and courtyard configuration to determine the effect on the internal courtyard percentage shaded area. This research aims to explore the potential benefits of using courtyards as a daylight shading design as a strategy in buildings. Besides, it is also to examine courtyard design variables in enhancing visual comfort, particularly in the context of commercial building design in Malaysia. Kuala Lumpur is chosen to represent the tropical climate region. The aim is achieved by identifying optimum courtyard ratios that can improve daylight, shading, and visual comfort that make courtyards functional and usable spaces. Results show that a small and deep courtyard is found to be best suited to tropical climate conditions with the configuration of the courtyard’s height being double the size or more than the size of the courtyard’s width. This courtyard ratio is able to produce a full shaded area during daytime. While courtyard length does not have any impact on the percentage of shaded area, wide and narrow courtyard need to adapt to the tropical climate constraint by having aided shading strategies such as multi-layered height of trees, independent covered structures like a canopy or gazebo, shading panels, awnings, and extended roof overhangs.

Cocoseae: A dominant arecoid palm element in the Deccan K-Pg flora of Madhya Pradesh, Central India

Here, we report the occurrence of a large number of fossil fruits with distinctive germination pores along with a petrified stem, resembling morphologically and anatomically the extant palm tribe Cocoseae Mart. ex Dumort. of the subfamily Arecoideae. The permineralized fruits and locule casts, assigned to Palmocarpon drypeteoides (Mehrotra, Prakash, and Bande) Manchester et al., and the stem of Palmoxylon sp. were recovered from the Deccan Intertrappean Beds (late Mastrichtian–early Danian sediments; c. 66–65 Ma) of Umariya Ryt. village in Dindori District, Madhya Pradesh, Central India. Using micro–computed tomography (mCT) and standard thin section methods, we observed for the first time that these fossil palm fruits have a persistent basal trimerous perianth. These fossils, along with other reports in the literature, suggest that cocosoid palms were dominant among the arecoid palms of the Deccan Intertrappean beds in Madhya Pradesh. At present, the modern relatives do not grow in the same area but they occur in tropical forests of southeastern and eastern India as well as other regions including parts of South America, Asia, Europe, and Africa. The expansions and retraction of the cocosoid palms likely coincide with climate change. The recovery of cocosoid fossils (present and earlier reported) and previously described tropical elements from the same fossil locality suggest the existence of tropical climatic conditions during the period of depositions. We also revisit the historical phytogeography of the cocosoid palms.

Managing Bee’s Health During Dearth Periods: A Review of Pollen and Nectar Substitutes for Tropical Climates

Bees are essential pollinators, playing a critical role in both ecosystems and agriculture. Aside from their well-known honey production, royal jelly and wax, the significance of pollen and nectar as essential food sources for bees cannot be overstated. In dearth periods such as those occurring between major flowering seasons or environmental factors like drought, bees may encounter difficulties in finding sufficient food for sustaining their colonies. In tropical climates, the dearth period lasts longer compared to other climatic conditions. The implementation and advancement of artificial diet involving substitutes for pollen has been explored as a means to sustain brood rearing, egg laying and foraging activities. This approach aims to ensure an adequate bee population within the colony. Additionally, these substitutes improve energy use and disease resistance by influencing gene expression linked to immunological responses, protein synthesis, and glucose metabolism. Therefore, providing pollen and nectar substitutes to bee colonies during dearth periods can prove advantageous in preserving the overall health and growth of the hives in tropical climatic conditions.

Thermal Behaviour of Cool-Pavement Materials Development using Palm Oil Shell Aggregate

Cool-pavement technology has emerged as a potential solution to environmental issues posed by the urban heat island phenomenon, with surface temperature acting as a vital parameter in the evaluation of its thermal performance. This study focuses on the thermal performance results of modified asphalt concrete mix, wherein palm oil shell (POS) serves as a replacement for fine aggregate. Modified asphalt samples prepared using the Marshall Mix Design, with varying degrees of fine aggregate substitution (0%, 10%, 20%, 30%, 40%, and 50%), underwent a 24-hour continuous surface temperature measurement over a span of 20 days, under real-world tropical climate conditions. The findings demonstrated that sample P5, comprising 50% fine aggregate substitution, exhibited the highest reduction in surface temperature when compared to control sample P0, registering a significant decrease of up to 3.29°C during the period of peak solar intensity. ANOVA test-based statistical analyses confirmed significantly lower temperatures for all test samples, barring sample P1 (10% aggregate replacement), relative to the control sample. The results highlight the efficacy of POS as a fine aggregate substitute in asphalt concrete, significantly lowering asphalt pavement surface temperature, thereby endorsing the potential use of POS-modified asphalt in cool-pavement applications.

“Out-of-India” dispersal of the extinct fabaceous genus Podocarpium Braun ex Stizenberger

Podocarpium is a well-known extinct single-seeded legume genus having extensive Cenozoic fossil occurrences from East Asia to central Europe. To date, there have been no fossil records of this genus from South Asia, including India. Here, we report and describe for the first time a well-preserved fossil pod from the early Eocene of Rajasthan, western India, assigned to extinct Podocarpium based on detailed morphology. It is characterized by an asymmetrical, oblique valve with a single oblong seed, a distinctly curved stipe, a wingless margin, a prominent vascular strand along the dorsal suture that anastomoses into the apex, a weakly curved ventral suture, fine reticulate veins, a short acuminate apex, and a narrowly acute base. This discovery is the oldest fossil evidence of Podocarpium recorded to date worldwide. Together with previous fossil records, we suggest an “Out-of-India” dispersal hypothesis to explain the biogeography of this extinct legume genus. It might have originated under warm and humid tropical climate conditions in the early Eocene of India (South Asia), then migrated to China (East Asia), and subsequently spread north and westward to Europe.

Studies on Genetic Divergence in Cabbage Genotypes in the Mid Hills of Solan District, Himachal Pradesh, India

Cabbage (Brassica oleracea var. capitata L.) is one of the most important vegetables of the family Brassicaceae and is grown under temperate to tropical climatic conditions for its head in more than ninety countries throughout the world. The diversity in cabbage is immense due to the presence of variation in shape, size, weight and maturity of heads. The greater the variability in the available germplasm, more would be the chances for selecting superior genotypes for use in breeding programmes or direct use as cultivars. Twenty three genotypes of cabbage including check variety, Golden Acre were evaluated in a Randomized Complete Block Design (RCBD) with three replications. The results concluded that twenty-three diverse genotypes of cabbage were grouped into four clusters. The resultant four clusters showed genetic diversity and maximum number of genotypes were accommodated in cluster I (12) followed by II (7), IV (3) and III (1). The maximum inter cluster distance was recorded between cluster II and III, therefore, the hybridization between the genotypes of cluster II and III can be performed to get superior hybrids or recombinants in segregating populations for further breeding programmes. Based on the mean performance, genetic distance and clustering pattern, inter-varietal crosses can be made which may be advantageous in creating wider variability for better heterotic combinations and transgressive segregants in cabbage.

Growth Responses of Okra (Abelmoschus esculentus L. Moench) to Selected Plant Growth Regulators

This study was conducted to evaluate the effects of two types of plant growth regulators (PGRs) which are gibberellins (GA3) and Paclobutrazol (PBZ) on the growth and photosynthetic pigment (chlorophyll) of Okra (Abelmoschus esculentus L. Moench) plants. Exogenous applications of GA3 and PBZ with different concentrations (i.e. 20, 40, 80 and 100 mg/L) were sprayed on two-week-old Okra plants under the nursery stage. The control plants were only treated with distilled water. The stem diameter (mm) of treated and control plants was measured weekly. At the end of the experimental period, data on growth characteristics such as plant height (cm), leaf area (cm2) and number of leaves were recorded. The estimation of chlorophyll was measured using the SPAD-502 Chlorophyll Meter. Results showed that the plant morphological characteristics of Okra plants were significantly affected by the application of GA3 and PBZ (P<0.0001). In addition, stem growth (expressed as stem cross-sectional area- mm2) of Okra plants was significantly increased with increasing GA3 concentrations. In contrast, applying PBZ reduced Okra plants' stem growth. This study highlighted the major effects of GA3 and PBZ on the growth of Okra plants when planted under tropical climate conditions.

Thermal Comfort Assessment of UPM Engineering Library in Tropical Climate Conditions

Thermal comfort is the study of indoor comfort level feel by the occupant in a room. This paper presents the study of thermal comfort that had been carried out in the library of engineering faculty at Universiti Putra Malayia in Serdang, Malaysia. The study was made in 4 days from 9 am to 11 am on October and November. This study was carried out to assess their thermal conditions during the occupants’ study hours. Thermal comfort variables were measured during study hours too. Qualitative and Quantitative data analysis showed that engineering library meet the requirement of comfort zone thermal conditions of ASHRAE standard 55 and ISO 7730. The result shows the environmental condition of the library is neutral to slightly warm in 4-point ASHRAE scale. The linear regression between Predicted Mean Vote and Operative Temperature reveals that the maximum acceptable temperature in this field of study is 26.5ºC.

Green roof thermal performance of small-scale prototype using IES-VE simulation in tropical climatic condition

Abstract This study investigates the thermal performance of green roof systems in a tropical climate, focusing on the small-scale building prototypes. Batu Pahat, Malaysia is experiencing the increasing temperatures due to climate change. Green roofs are considered as a potential solution, but their effectiveness depends on various factors such as building orientation, solar shading, and thermal resistance (R-value). Therefore, modeling and simulation are crucial for understanding green roof thermal behaviour. This study employs the Integrated Environmental Simulation Virtual Environment (IES-VE) software for analysis. Three identical small-scale buildings were constructed, one with Portulaca Grandiflora (PGR) plants, another with Alternanthera Paronychioides (ATN) plants, and a control roof with no vegetation. The R-values from the on-site green roofs were measured at 0.8899 m²K/W for PGR and 1.1477 m²K/W for ATN, while the control roof had an R-value of 0.1 m²K/W. Green roofs with higher R-values demonstrated a substantial reduction in indoor temperatures, making them a valuable solution for improving thermal comfort in tropical climates. This study underscores the importance of green roofs in mitigating rising temperatures in tropical climates. Simulation using IES-VE approved that green roofs can potentially reduce indoor temperatures, demonstrating their suitability for tropical regions. These findings have significant implications for sustainable building design and urban planning in hot and humid climates.

Neutral interactions between native Alternanthera sessilis and exotic Alternanthera philoxeroides along a light gradient under tropical climatic conditions

AbstractRiparian ecosystems are under a serious threat of invasion due to the clearance of riparian vegetation, which allows for increased light levels at ground level. This study presents the interactions between native Alternanthera sessilis (L.) R. Br. ex DC and invasive Alternanthera philoxeroides (Mart.) Griseb. during the colonization stage along a light gradient under tropical climate conditions. We conducted a 6 week growth experiment with monocultures of A. philoxeroides and A.sessilis and mixed communities of two species under four light levels (100%, 46%, 26% and 14% of full sunlight). Exposure to full sunlight (nearly 1800 μmol m−2 s−1) resulted in a significantly high biomass accrual in both species. However, biomass accrual did not correlate with the light intensity. At higher shade levels, reduction of lateral spread and shoot/root ratio was observed. Community composition had no influence on biomass accrual or morphological variations. Plasticity index values were approximately same in both species. Total relative yield was approximately two in all shade conditions, indicating that the two species interact neutrally along the light gradient. Therefore, the results of the study indicate that increased light levels will accelerate the proliferation of both species in riparian zones. Nevertheless, increased or decreased shade is unlikely to alter neutral interactions between A. philoxeroides and A. sessilis.