Humid Climate Regions Research Articles

Evaluation of Statistical Downscaling Methods for Simulating Daily Precipitation Distribution, Frequency, and Temporal Sequence

HighlightsNine statistical downscaling methods from three downscaling categories were evaluated.Weather generator-based methods had advantages in simulating non-stationary precipitation.Differences in downscaling performance were smaller within each category than between categories.The performance of each downscaling method varied with climate conditions.Abstract. Spatial discrepancy between global climate model (GCM) projections and the climate data input required by hydrological models is a major limitation for assessing the impact of climate change on soil erosion and crop production at local scales. Statistical downscaling techniques are widely used to correct biases of GCM projections. The objective of this study was to evaluate the ability of nine statistical downscaling methods from three available statistical downscaling categories to simulate daily precipitation distribution, frequency, and temporal sequence at four Oklahoma weather stations representing arid to humid climate regions. The three downscaling categories included perfect prognosis (PP), model output statistics (MOS), and stochastic weather generator (SWG). To minimize the effect of GCM projection error on downscaling quality, the National Centers for Environmental Prediction (NCEP) Reanalysis 1 data at a 2.5° grid spacing (treated as observed grid data) were downscaled to the four weather stations (representing arid, semi-arid, sub humid, and humid regions) using the nine downscaling methods. The station observations were divided into calibration and validation periods in a way that maximized the differences in annual precipitation means between the two periods for assessing the ability of each method in downscaling non-stationary climate changes. All methods were ranked with three metrics (Euclidean distance, sum of absolute relative error, and absolute error) for their ability in simulating precipitation amounts at daily, monthly, yearly, and annual maximum scales. After eliminating the poorest two performers in simulating precipitation mean, distribution, frequency, and temporal sequence, the top four remaining methods in ascending order were Distribution-based Bias Correction (DBC), Generator for Point Climate Change (GPCC), SYNthetic weather generaTOR (SYNTOR), and LOCal Intensity scaling (LOCI). DBC and LOCI are bias-correction methods, and GPCC and SYNTOR are generator-based methods. The differences in performances among the downscaling methods were smaller within each downscaling category than between the categories. The performance of each method varied with the climate conditions of each station. Overall results indicated that the SWG methods had certain advantages in simulating daily precipitation distribution, frequency, and temporal sequence for non-stationary climate changes. Keywords: Climate change, Climate downscaling, Downscaling method evaluation, Statistical downscaling.

Study of thermal comfort in the residents of different climatic regions of India-Effect of the COVID-19 lockdown.

Thermal comfort standards are essential to ensure comfortable and enjoyable indoor conditions, and they also help in optimizing energy use. Thermal comfort studies, either climate chamber-based or field investigation, are conducted across the globe in order to ascertain the comfort limits as per the climatic and other adaptive features. However, very few studies are conducted when the occupants are subjected to a stressed condition, like the COVID-19 lockdown, which may not only have the health impacts but also have psychological impacts on the adaptation. In this paper, we present the results of the online study conducted regarding the status of thermal comfort during the COVID-19 lockdown in India. A total of 406 complete responses were collected from subjects located across 3 different climatic regions of India, that is, cold climate, composite climate, and hot and humid climate. Variations in clothing insulation, thermal sensation, and preference were noted across the different climatic regions. We also present the variation in opening of windows and running of fans with the variation in outdoor mean air temperature. The self-judged productivity, comfort, desire to go outdoors, and effectiveness of working from home were seen to vary with the increase in the days of lockdown.

Investigation on the Thermal Condition of a Traditional Cold-Lane in Summer in Subtropical Humid Climate Region of China

A Chinese traditional narrow street, named Cold-Lane, can create a microclimatic zone that provides pedestrian thermal comfort under hot and humid climate conditions. This phenomenon was observed through experimental measurement during the summer of 2016. The heat transfer rate over the pedestrian body surface was calculated to reveal why pedestrians experience a cool sensation, and computational flow dynamics (CFD) simulation was carried out to study the influence of the street aspect ratio on the shading effect. It was found that the perception of thermal comfort can be attributed mainly to the radiation between the relatively cool surrounding walls and the human body, and the wind velocity has little effect on sensible heat dissipation. The cool horizontal and vertical surfaces in the street canyon are mainly due to the shading effect as a result of the small aspect ratio, which is a typical characteristic of the traditional Chinese street. The shading effect of the high walls on both sides creates the cooling effect of this narrow street.

A solar regenerated liquid desiccant evaporative cooling system for office building application in hot and humid climate

In this paper, we provide the thermal analysis and design methodology of a liquid desiccant assisted dew point indirect evaporative cooling system. The purpose of the system is to serve as an alternative for conventional vapour-compression based building air conditioning systems in providing satisfactory human thermal comfort conditions in the hot and humid climatic regions. The main features of the study are the following: i) novel incorporation of a forced parallel flow direct solar regenerator and a dew point indirect evaporative cooler within the same air conditioning unit; ii) detailed thermal modelling of each of the system components with fewer simplifying assumptions compared to earlier works; iii) large cooling capacity (~18.8 TR) under harsh climate; and, iv) a comprehensive year-round case study for system operation in a hot and humid location (Kolkata, India). Our thermal model is validated with a reference model study. The maximum room air temperature predicted by the current system for year-long analysis is 26.7 °C. The thermal COP of the system for diurnal operation in the most humid month of a calendar year (July) varied between 0.40 and 0.96. The cooling system can prevent overheating of the conditioned space, as specified by ASHRAE Standard 55–2017, throughout the year.

Seroprevalence and risk factor analysis of human leptospirosis in distinct climatic regions of Pakistan

Background: Leptospirosis is a worldwide emerging infectious disease of zoonotic importance and large epidemics and epizootics have been reported all over the globe. Methods and materials: A cross survey study was conducted to estimate seroprevalence of human leptospirosis in climatically distinct regions of Pakistan and to identify the risk factors associated with the disease. Blood samples from 360 humans were collected through convenient sampling, 120 from each of three study areas. Serological testing was performed using ELISA kit as per manufacturer's recommendations. Results: The results showed an overall prevalence of 40.83% (95% CI; 35.71–46.11). Statistical analysis showed significant (p < .05) differences in leptospiral seroprevalence in three different geographic locations, with highest in humid sub-tropical climatic region (50.83%; 95% CI; 41.55–60.07), followed by semi-arid region (44.16%; 95% CI; 35.11–53.52) and lowest in hot and dry region (27.50%; 95% CI; 19.75–36.40). After multivariate analysis age, gender, exposure to flooding water, source of water usage, disinfection schedule of surroundings and history of cut and wound were found significantly associated with the seropositivity of Leptospira. Conclusion: The present study, first to uncover seroprevalence of human Leptospira in different climatic regions of Pakistan, alarms about effect of climate on prevalence of Leptospira in the region.

Assessment of drought and wet projections in the humid climatic regions for Pakistan

Investigation of extreme hydrological events are necessary for planning and designing hydrological structures. In this study, we examine and project two hydrological extremes of drought and wet conditions over the north and eastern regions of the country. A statistical procedure of the Reconnaissance Drought Index at the annual time scale was used to combine the monthly rainfall and temperature data for the assessment of extreme drought and wet events. These hydrological extreme events were combined with Index-Drought Procedure using L-moments to obtain study results. Homogenous regions were satisfied for both the extremes based on statistical measures. Two statistical tools were used to select suitable probability distributions in the form of Generalized Pareto and Pearson Type-III distributions to discuss drought risk and wet conditions in the regions. Secondly, regional projections of drought risk and wet conditions were performed based on regional quantiles at different interarrival periods which show greater chances of the wet condition in region one while drought risk in region two. Lastly, at-site projections were carried out for all the included sites for both extremes at various interarrival periods using the suitable probability distributions. Both at-site and regional projections show greater similarity at lower while uncertainty at higher interarrival periods. As droughts and wets cover, a large area, therefore, regional results are more functional and better for regional planning and development programs. These statistical projections will help planners of water resources management and hydrological extremes in the study area.

Performance evaluation and comparative analysis of trans-critical CO2 booster refrigeration systems with modified evaporative cooled gas cooler for supermarket application in Indian context

Abstract In this paper, the performance of CO2 booster refrigeration systems with eight different configurations for the supermarket application is analysed and compared with the conventional R404A system. The investigated configurations includes basic booster system with overfeed evaporators, as well as the adoption of modified evaporative cooled gas cooler. The analysis is mainly focused on power consumption, energy efficiency, and total equivalent warming impact while using these systems throughout the year in Indian climatic conditions. The steady-state thermodynamic model is developed and validated for the booster systems available in the literature. Subsequently, the analysis is extended for all the configurations on the year-round operation (2017–18) for five major cities in India of different climate regions. The result shows that the basic booster system with both low and medium temperature flooded evaporators integrated with modified evaporative cooler system is the best configuration in all cities. The rank of performance is higher for Delhi (composite climate region), followed by Ahmedabad, Bangalore, Chennai, and Kolkata (hot and humid climate region). The BBSM-LT+MT system, improve the SEER maximum up to 49%, whereas the annual energy saving up to 35%, compared to the BBS. Subsequently, the maximum reduction in indirect emission (TEWI) is found to be 18% compared to the conventional R404A system.

A Demographic Study on Cases of Drowning with Special Reference to Histopathological Changes of Lung and Other Tissues in a Tertiary Centre

Introduction:Drowning is the 3rd leading cause of unintentional injury deaths.As drowning is a preventable cause of mortality, our aims for the benefit of society at large is to minimize the events as far as possible. Objective:A clear knowledge about factors which play a major role behind such incidences is important.It has equal forensic importance as determination of cause and manner of death require thorough investigation. Methodology: We conducted one-year study of demographic variables and the histopathological changes in relation to lung and splenic tissues in cases of drowning deaths, in the hot and humid climatic region of Eastern India.Results: The demographic findings were presented in graphs and charts. However, none of the commonly known autopsy findings (histopathological) are found to be individually confirmatory of drowning. Conclusion:Several factors inclusive of autopsy findings, biochemical examination, radiological and molecular technique,are needed to be taken together as complementary methods to conclude drowning as the cause of death when bodies are recovered from water.

The effect of trees on human energy fluxes in a humid subtropical climate region.

Trees are considered to be an effective tool for improving human thermal comfort in hot climates and have been widely used in landscape architecture. However, it is not always clear how trees affect human-environment energy fluxes. In this study, an in-depth analysis of four common tree species was undertaken based on comprehensive field measurements, in terms of how each tree and its characteristics affected the energy fluxes of a person in a humid subtropical climate region. Results showed that the largest effect of trees was on radiation fluxes, with a much smaller effect on the convective and evaporative fluxes. For a person standing in shade, a tree can reduce approximately 25% of the absorbed radiation compared with an open reference point. Moreover, the cooling effect on radiation components was found to be greater in the solar radiation domain than in the terrestrial radiation domain. Solar radiation and ground surface temperature had the largest effect on a human energy budget, which was affected by characteristics of the trees and the thermophysical properties of ground surfaces. The effect from relative humidity and wind speed was quite minimal. For the four common tree species in this study, Ficus microcarpa had the best thermal performance by reducing the most absorbed solar radiation flux. This study shows a detailed empirical research about the thermal effects of trees on a person, providing recommendations for tree species selection in urban design.

Yield, quality, water productivity and economic assessment of sweet corn under irrigation and nitrogen management in humid tropical climate

A field experiment was conducted during three consecutive winter seasons of 2013-14 to 2015-16 in the Indo-Gangetic plains encompassing humid tropical climatic region to study four irrigation regimes (gravity drip at 1.0, 0.8 and 0.6 ETc and surface irrigation) and four nitrogen management (100% RDN, 75% RDN + 25% RDN as vermicompost, 75% RDN + 25% RDN as FYM and 75% RDN + 25% RDN as mustard oilcake) on sweet corn. The results showed that surface irrigation with 75% RDN + 25% RDN as vermicompost was found the best treatment combination for maximum yield and economic realization which being competitive with drip irrigation at 1.0 ETc with 75% RDN + 25% RDN as vermicompost. Relatively higher quality parameters and moderate water productivity were observed with drip irrigation schedule at 1.0 ETc. The findings portray the precise planning and efficient management of available water and nitrogen resources for sweet corn growers.

Privacy Cognition of Spaces by Agraph Tools in Temperate Humid Climatic Region of Iran

Purpose The aim of this research is to understand the spatial configuration between the spaces by using the space syntax method for close, semi-open and open spaces. Design/ methodology/approcach The method of this study is Agraph that is one of the tools of space syntax method. Agraph tool represent spatial relation between the spaces with graph and calculation included. During the research, all the space such as close, semi-open and open spaces analyzed with space syntax method. Findings The finding of this investigation demonstrated that although traditional houses have different topological issue, from different level of economy but the concern of organizing spaces under context and social hierarchy were same between all of them. Furthermore, inhabitants in different level of economy attempt to organize space by concerning privacy and public issue. Designing of traditional building in temperate humid climate is in a way to respond to the harsh climatic condition and to their cultural behavior. Research Limitations/Implications Four different types of Iranian traditional buildings where are located in the temperate-humid climatic region of Iran analyzed for discovering the social relation of the spaces in Gilan province. These four different categories included of one bedroom to more than five bedroom buildings. Hence, this research just considered the analysis for the houses with less than five bedrooms. Practical Implications Applying Agraph tool for understanding privacy and public degree of spaces. Social Implications Applying Agraph tool on Iranian traduational architecture for estimating the degree of privacy in each spaces. Since in Iranian culture spaces organized based on the public and privacy factor. Originality/Value The original of this research is to finding the degrre of privacy in each building with different level of economy based on Agraph tool. However, the result was different from the previuse studies. The consequence of Agraph tool needs some modification for applying in architectural purposes.

Five years’ exposure of elevated atmospheric CO2 and temperature enriched recalcitrant carbon in soil of subtropical humid climate

Atmospheric CO2 and temperature levels are predicted to increase to 550 μmol mol−1 and by 2.0–4.5 °C higher than the present, respectively, by the middle of the 21st century. Our experiment was focused to study the impact of elevated atmospheric carbon dioxide (CO2) (500 ± 20 ppm) and temperature (> 2 °C than ambient) and their association on soil respiration and total organic carbon (TOC) along with its different pools such as: active pool (AP), passive pool (PP), particulate organic carbon (POC) and mineral-associated organic carbon (MOC) in 0−30 cm soil depth under field based open-top chambers for 5years (2011–2016). Elevated CO2 (eCO2), elevated temperature (eTemp) and their association (eCO2+eTemp) resulted in significant 3.09, 11.1 and 2.76 % reduction in TOC, respectively, in 0−30 cm soil depth over ambient condition. In all predicted climatic conditions, depletion of AP and POC were observed. Conversely, carbon enriched in PP and MOC. The outcome of the soil respiration study revealed that even though cumulative carbon mineralization values were lower in soil exposed to eCO2 and eTemp, under carbon depleted condition, the carbon mineralization efficiencies were higher. So, it can be concluded that in future climate scenario soil will act as a net source to atmospheric CO2 in subtropical humid climatic regions.

INTER-COMPARISON BETWEEN MODIS SATELLITE-BASED AND AERONET GROUND-BASED AEROSOL OPTICAL DEPTH PRODUCTS IN VIETNAM

Although a number of studies have extensively inter-compared the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite-based aerosol optical depth (AOD) with the Aerosol Robotic Network (AERONET) ground-based AOD on both global and regional scales, almost no similar studies have been conducted for Vietnam - a humid subtropical climate region. For the first time, inter-comparison between the MODIS Terra and Aqua Collection 6.1 (C6.1) Dark Target (DT) 10 km, Deep Blue (DB) 10 km, and merged DT-DB 10 km with the AERONET AODs has been performed in different areas with different surface types and different climatic characteristics in Vietnam. Three investigated AERONET stations are Nghia Do (urban), Son La (mountainous rural), and Bac Lieu (coastal urban) with the studying periods of 2010 - 2016, 2012 - 2017, and 2010 - 2017, respectively. Our findings showed the better performances of DB algorithm than those of DT and DT-DB products in the urban area. Additionally, all MODIS AOD algorithm performed worse over the coastal area compared to those in the non-coastal areas. Generally, the ability of all the MODIS AODs to catch up the monthly-mean AERONET AODs has been expressed in this study.

Thermal comfort of urban spaces using simulation tools exploring street orientation influence of on the outdoor thermal comfort: a case study of Jeddah, Saudi Arabia

AbstractAt present, the environmental quality of urban regions and outdoor spaces has turn out to be one of the main issues facing both climatologists and designers, which could be identified through their research outcomes. It is argued that the urban configuration affects the micro-climate of the urban outdoor spaces. The street’s orientation form was identified as an element, which impacts the urban environment with regards of receiving passive solar, solar radiation and reflection against urban absorption, wind flow and the possible urban cooling techniques. The key purpose of this study is to look into the urban configuration factors affecting the human thermal outdoor comfort in Jeddah city as an example of hot humid climate regions. To accomplish its aim, the research is divided to two sections. The first one illustrates the problem of the research, then generally reviews the literature associated with the outdoor human thermal comfort; in addition, it discusses the relationship between street orientation and micro-climate. The second section highlight the assessments carried out between four different orientations of urban streets from two different districts in Jeddah city, using ENVI-met software. The research adopts three environmental variables to be examined, namely air temperature, wind speed, relative humidity together with pedestrian thermal comfort as indicators for predicted mean vote, during summer and winter seasons. The outcomes of the comparison assist to identify decisions related street networks to achieve the desirable human outdoor thermal comfort in such an urban environment.

Evaluation of Different Rainfall-based Drought Indices Detection of Meteorological Drought Events in Imo State, Nigeria

Drought Indices are extensively adopted as a drought detection and monitoring tool in all climatic regions. This study assesses and compares the performance of four rainfall based drought indices, Deciles index (DI), Percent of Normal Index (PNI), Standardized Precipitation Index (SPI) and Z-score Index (ZSI) in detection and classification of drought events in Imo state , a humid environment of Nigeria from (1982 to 2016). The resultshows that droughts do occur in humid climatic region of Nigeria. The various indices differ in their detection and classification of drought events in the study area. However, they classified 2007 and 2008 as the year with the most severe drought event in the state. There is high correlation (r &gt; 0.70) among the four indices, with ZSI and PNI showing the highest relationship to SPI (r= 0.97). The differences observed among the drought indices in detecting drought events in the study area can be reduced by using multiple drought indices in addition to the use of SPI in drought assessments especially in Nigeria since technological advancement in drought monitoring software’s has made it easier. Also it is worthwhile to research on why drought detection varies with indices.&#x0D; Keywords: Drought assessment, Rainfall-based drought indices, humid environment, Imo state, Nigeria.

Affordable retrofitting methods to achieve thermal comfort for a terrace house in Malaysia with a hot–humid climate

Although various cooling approaches have been proposed to overcome the thermal discomfort in residential buildings, tropical developing countries still lack affordable and effective retrofitting methods. The objective of this study was to evaluate the effectiveness of an affordable retrofitting method with high-density polyethylene (HDPE) nets as roof covers for shading over the roof, supported by full day free-running ventilation, and heat insulation above the ceiling of residential buildings in hot–humid climate regions to overcome the thermal discomfort. Field measurements were carried out in a corner terrace house in Malaysia, from September to December 2018. The roof cover with HDPE nets maintained a consistent surface temperature at the roof tiles and reduced the convective heat flux by approximately 70–80% in the attic and 88% in the room. Further, it improved the compliance (acceptability: 80%) of the whole-day mean operative temperature in the room (hot–humid climate) by 10%. The roof cover can effectively provide thermal comfort in residential buildings in Malaysia, which has a hot–humid climate. Alongside active cooling with the ceiling fan, required comfortable indoor temperature can be reached under the hot–humid climate, particularly during the night-time. Furthermore, the zero-energy-consuming, low-cost low-technology roof cover method is very suitable for low-cost houses with roof tile in hot–humid climate regions.

Building Volume Effects on Ambient Temperature In The Kuala Lumpur City

Buildings not only generate anthropogenic heat but also store and release heat energy which able to alter the urban microclimate. The heat released in the atmosphere contributes to the rise in ambient temperature, causing thermal discomfort towards urban dwellers, especially in hot and humid climate regions such as the Kuala Lumpur City. Due to urbanization, many buildings were erected leading to higher heat absorption within this city. This study aims to investigate the contribution of building volume on the ambient temperature of the Kuala Lumpur City. Using the Weather Research and Forecasting (WRF) simulation model, the ambient temperature of the city was regenerated within an intermonsoon phase (April) in the year of 2018. This period was chosen to reduce the synoptic forcing. Building footprints stored in GIS-based vector dataset was used to estimate building volumes within the city. Spearman correlation test and Kruskall Wallis test has revealed that the building volumes within the city has significantly affected the ambient temperature causing thermal discomfort towards the urban dwellers especially during the day. Spatial examination revealed that higher building volume contribute to warmer environment within the city centre. Thus, optimization of the building volume should be seriously considered especially during urban planning decision making.

Framework for model predictive control (MPC)-based surface condensation prevention for thermo-active building systems (TABS)

The potential risk of developing surface condensation keeps thermo-active building systems (TABS) from being applied in buildings located in partly warm and humid climate regions. This study presents a framework for model predictive control (MPC)-based surface condensation prevention that can avoid the surface condensation during the cooling periods when the TABS is in operation. Because MPC determines the input signal for the system not only on the basis of the current states but also on the impact that the actions will have on the future states, it is suitable for anticipatory surface condensation control that must respond to both dynamic indoor condition changes and the time-delay in hygrothermal transfer in advance. Heat and moisture transfer dynamic models were developed for prediction of future states and these dynamic models were calibrated with the measured data to improve the surface condensation prediction accuracy. On the basis of future states predicted by the calibrated dynamic models, the MPC-based condensation prevention framework adjusts the surface temperature for the TABS in ways that ensure indoor thermal comfort and energy efficiency without the development of surface condensation. The results demonstrated that the MPC-based TABS operation achieved 21.0 − 29.6% site cooling distribution energy savings compared to the conventional forced air-based cooling mode depending on the climatic regions; in comparison between the TABS governed by the MPC framework and by the on/off control, 2.5 − 10.0% more site cooling distribution energy savings were achieved through use of the MPC framework than through use of the on/off control.

Sensitivity of extreme precipitation in Texas to climatic cycles

The vast areal extent of Texas, USA, observes acute variations in extreme precipitation, which result in devastating floods in various regions. Hydrometeorological literature suggests that these precipitation extremes are driven by the changes in global-scale climatic cycles. This study analyzed potential statistical links between Atlantic- and Pacific Ocean-based climatic cycles and annual precipitation extremes in Koppen–Geiger climate regions of Texas. Sensitivity analysis was done for annual precipitation extremes and differing phases of the most correlated climatic cycles. The study also analyzed the spatial variation of climatic indices and determined the projected increments in annual precipitation extremes as per the highest historically recorded increments or decrements in the most correlated climatic cycles in consecutive months. Weather stations with lower elevation and higher average precipitation are likely to observe higher extreme precipitation events in the warmer AMO state. Sensitivity analysis showed that a 20% decrement in empirical probabilities of projected precipitation extreme events corresponded to a decline of 35% in the same for humid subtropical climate region. The humid subtropical climate region is highly prone to devastating floods after heavy precipitation events. Results of the study will help prepare regional water boards for extreme precipitation events with reliable long-term forecasts of climatic cycles.

Combating the COVID-19 battle with personal protective equipment (PPE) armamentarium.

Combating the COVID-19 battle with personal protective equipment (PPE) armamentarium.