Daily Insolation Research Articles

Mapping local climates in highly heterogeneous mountain regions: Interpolation of meteorological station data vs. downscaling of macroclimate grids

Topography modulates air and soil temperature and gives rise to local climates that may strongly deviate from regional macroclimates. These local climatic conditions determine the distribution of many organisms but are hardly accounted for by coarse-grained macroclimate grids. Downscaling macroclimate grids or interpolating high-resolution climate surfaces from weather station data has thus become a staple in ecological research. Against this background, topographically complex territories pose a challenge, as downscaling and interpolation techniques are susceptible to high topographic heterogeneity. Simultaneously, these regions will act as refugia and preserve biodiversity amidst the challenges of climate change. This contrast renders choosing the technique to derive local climatic conditions under high topographic complexity critically relevant.In this study, we compared how interpolation and downscaling techniques predict the local climates of topographically heterogeneous territories. We interpolated monthly average temperatures from weather stations in a Southern Italy mountain region and downscaled WorldClim and CHELSA macroclimatic grids from their native 30 arcsecs to 10 m resolution. We carried out the interpolation and downscaling procedures by employing four commonly used statistical algorithms and by including physiographic descriptors (altitude, northness, eastness, distance to the coast, and monthly average of daily clear-sky insolation time) known to determine local climatic conditions. We compared the techniques' predictive performance via leave-one-out cross-validation. We extended the comparison over the study area to identify where the techniques most strongly diverged and evaluated how interpolation and downscaling techniques fare against environmental extrapolation.Although the interpolations scored the best values across all error metrics, interpolating weather station data and downscaling WorldClim yielded essentially equivalent predictions of local climates in the cross-validations. Differences between the two techniques emerged during the spatial comparison, where downscaling WorldClim produced biased and less detailed monthly climate surfaces. On the contrary, weather station interpolation was affected by environmental extrapolation in the study area's most internal and topographically heterogeneous landscapes. Downscaling CHELSA severely over-smoothed local climatic conditions during both cross-validations and spatial comparisons, possibly due to lacking climate variability in the native product itself.We demonstrated that technique and data source choice affect the prediction of local climates in topographically heterogeneous territories. Despite its limitations, we argue that interpolating weather station data better accounted for local-scale topographic effects. These effects form an integral part of the microrefugia that will shelter mountain communities from warming climates. We thus recommend carefully considering the techniques chosen to unravel the intricate climatic mosaics of topographically heterogeneous territories.

Length of astronomical seasons, total and average insolation over seasons

Daily insolation at a given latitude is often used in the explanation of the long-term variations of paleoclimate records. However, the length of astronomical seasons, which has been paid less attention, could also be important. This paper provides an original calculation of the length of these seasons using the eccentric anomaly. The past and future long-term variations as well as the spectral characteristics of the length of astronomical seasons, of the total and average insolation over the astronomical seasons and of the caloric insolation are shown and compared. The length of astronomical seasons is only a function of climatic precession. The total irradiation for a given latitude and an astronomical season is mainly a function of obliquity except that it is mainly a function of eccentricity in a latitudinal band that is season dependent and from where the phase between obliquity and total irradiation reverses (e.g. ∼11.5°N for the astronomical northern hemisphere summer half-year). The spectral characteristic of the mean insolation over the astronomical summer half-year varies in latitude and time. It contains stronger obliquity signal in high latitudes than in low latitudes, but the obliquity signal already gets very weak at 45°N/S leaving the dominance of climatic precession between 45°N and 45°S. The variation of the mean summer half-year insolation over the last 1 Ma is characterized by a Mid-Brunhes transition at ∼450 ka BP, with a dominant role of climatic precession at all latitudes before ∼450 ka BP but significantly enhanced role of obliquity in high latitudes after this time. The simultaneous weakening of the variations of climatic precession and obliquity around 800 ka ago, a time corresponding to the Mid-Pleistocene Transition, leads to weak variations in both total and mean seasonal insolation. The insolation of a specific case, the Holocene, is finally discussed. Depending on the sensitivity to different types of insolation, different climate variables and regions could show different evolution and trend during the Holocene.

Sunlight Autonomy for Buildings: A New Methodology for Evaluating Sunlight Performance in Urban and Architectural Design

ABSTRACT Due to urbanization and growing density in cities in the past century, metrics were introduced to assess daylight performance such as minimum sunlight hours and the daylight factor. The paper initially explores the shortcomings of early-stage daylight and sunlight evaluation methods. A novel methodology called Sunlight Autonomy (SA) is proposed for evaluating sunlight performance in buildings. The SA is based on the “Exposure to sunlight” criteria in EN 170307 “Daylight in Buildings,” where a computational method is used for the evaluation on a specified day. The SA concept expands the analysis temporally over the entire year, and spatially on building facades, leading to new metrics for a point of evaluation, and spatial metrics for buildings. The SA methodology is analyzed in a case study across four European cities. The SA metrics on facades between February 1st and March 21st, days in EN 17037, led to differences up to 63%. This revealed a significant shortcoming in EN 17037, relevant for Nordic regions. The differences of spatial metrics between March 21st and 50% of the year were within 5%, and up to 33% between February 1st and 75% of the year. The timestep affects the metrics and a window evaluation showed that the error of a 10-minute analysis was within 5% of daily insolation and 5 days for the annual SA. The potential of these metrics for urban planning and the architectural design process is examined. The interaction between SA and EN 17037, as well as other ongoing research developments, is discussed.

Multi-year variability of summer phytoplankton biomass and size structure in the northern Chukchi and East Siberian Seas, Arctic Ocean: role of light and nutrient availability

In the Arctic Ocean, the northern Chukchi and East Siberian Seas (NCESS) are vulnerable to climate change due to warming, sea ice melting, and surface freshening. To investigate how local physical forcing affects phytoplankton biomass and communities in this area, the multi-year (2015-2020) distributions of summer (August) chlorophyll-a concentrations and size structures using data collected by the Korea-Arctic Ocean Observing System (K-AOOS) program were investigated. The environmental characteristics and phytoplankton communities in the study area showed east-west regional differences. It is characterized by warm fresh waters and strong stratification to the east and cold saline waters and relatively high nutrient and sea ice concentrations to the west. Despite the differences between the east and west regions, patterns of the inter-annual variation in phytoplankton biomass and communities were similar across the entire study area, implying environmental controllers regulating phytoplankton in the NCESS. Inter-annually, higher sea surface salinity and weaker water column stratification were observed in 2017-2019 than in 2015 and 2020, implying the possibility of a potential modulation by the Arctic Oscillation. The shallower nitracline depth and higher surface nutrient concentrations since 2017 compared to the period from 2015-2016, indicate improved nutrient availability due to Atlantic water intrusion. However, average insolation has been relatively low since 2017, with the exception of August 2018. August mean phytoplankton biomass was highest in 2018 in the study area (average 83.7 mgm-2) and was dominated by large-sized phytoplankton. The low phytoplankton biomass in 2017 (23.9 mgm-2) and 2019 (62.4 mgm-2), despite similar characteristics of nutrient concentration to 2018, is likely due to lower average daily insolation in both years (206 μEm-2d-1 and 184 μEm-2d-1 in 2017 and 2019, respectively) compared to the 2018 average (271 μEm-2d-1). These results suggest that increased intrusion through upwelling of Atlantic water, along with nutrient loading, could be a pivotal driving factor contributing to this enhanced production in the NCESS, particularly under conditions where light levels are sufficient for phytoplankton growth and bloom development.

Long-term modeling of the performance of a solar still with phase-change material

Solar stills may be a small-scale and eco-friendly alternative to conventional, large-scale, and fossil-fuel-powered desalination plants due to growing worldwide water scarcity. However, solar stills suffer from low productivity which can be increased by optimizing the water mass and phase-change material (PCM) mass. Therefore, this paper aims at investigating the influence of water mass and PCM mass on the long-term performance of a solar still (SS) located in Poland. The long-term performance of SS is an important issue, as people need desalinated water all year round. Simultaneously, there is a limited number of publications concerning this issue in the open literature as most papers focus on the SS performance in a short-term period, usually no more than a couple of days. Therefore, research on the effect of water and PCM mass on SS performance in the context of long-term operation under various weather conditions, which is done in this work, is valuable and necessary. Additionally, this is the first time when the SS is investigated under Polish weather conditions. The study is carried out by conducting a theoretical analysis based on the mathematical modeling of the solar still. The mathematical model describing the thermal processes in the SS is established and validated using the experimental results. The results of simulations for average days for each month show that the maximum productivity of the SS is in July (3039 mL/m2/day with 5 kg of water), while the lowest is in October (900 mL/m2/day). The greatest annual SS productivity is 488.8 L/m2/year in Poland and is achieved with 5 kg of water and without PCM. The daily productivity is inversely proportional to the mass of water and the mass of PCM. The PCM reduces productivity by up to 11%. The results of daily simulations from April to October 2021 show that the daily productivity of the SS in Poland varies from 0.2 L/m2/day to 5.2 L/m2/day. The productivity of the SS investigated in this study in Poland is comparable to the productivity of solar stills investigated in countries with similar daily solar insolation and ambient air temperature.

Assessing the Performance of a Blackbody Solar Dryer

About 33.3% of global food production is lost to spoilage every year. At current rates, that amount is adequate for feeding an average of 300 million people around the world. This huge loss can be decimated to 13.17% if food spoilage is avoided or managed better. One technique for minimizing food waste is solar drying. West Africa and locations around the equatorial plane are described by average daily insolation of about 4-6 kWhm−2. In effect, this energy source could be applied to curb the problem of food spoilage and wastage. Another side attraction of drying with solar is that, it offers year-round availability of food crops. In this study, solar drying is investigated with the principle of blackbody radiation using an electronic data logger coupled with the Arduino Uno, SD Card Module, DHT22 Temperature and Humidity Sensor, SD Card, and Connecting wires to record temperature and humidity data. The output was 56.3°C and 46.8°C for the upper and lower limit of temperature respectively, yielding an average difference of about 10°C. The interaction of sensible blackbody radiation within a four-tier rock bed was crafted into a novel solar dryer design. With this relatively high-temperature gradient between the upper and lower, a blackbody solar dryer constructed was suitable to preserve the both quality and shelf life of agricultural produce.

Daily INSOLation (DINSOL-v1.0): an intuitive tool for classrooms and specifying solar radiation boundary conditions

Abstract. Climate modelling requires spending an extensive amount of time programming, which means reading, learning, testing, and evaluating source code. Fortunately, many climate models have been developed within the past decades, making it easier for climate studies to be conducted on a global scale. However, some climate models have millions of code lines, making the introduction of new parameterizations a laborious task that demands teamwork. While it is true that the high-complexity models perform realistic climate simulations, some researchers perform their studies using simplified climate models in the preliminary test phases. This realization motivated the development of Daily INSOLation (DINSOL-v1.0), a robust computer program to support the simplified climate models, performing solar radiation calculations while considering Milankovitch cycles and offering various simulation options for its users. DINSOL was intended to function as a program that supplies data (e.g. daily insolation, instantaneous solar radiation, orbital parameters of the Earth, and calendar dates), such as the Paleoclimate Modelling Intercomparison Project (PMIP). While preparing the boundary conditions of solar radiation for climate models, it was realized that the DINSOL model could also be a helpful tool for use in classrooms. Thus, it was decided that an intuitive graphical user interface would be required to cater to this educational purpose. The model was written in the Fortran 90 language, while its graphical user interface would be built using PyGTK, a Python application programming interface (API) based on GIMP ToolKit (GTK). Furthermore, the R language would also be used to generate a panel containing contour fields and sketches of the orbital parameters to support the graphical execution. The model evaluation made use of data from PMIP and other tools, and the data analysis was performed through statistical methods. Once all tests were concluded, an insignificant difference between the DINSOL-obtained results and the results obtained from other models validated the viability of DINSOL as a dependable tool.

Impact of air temperature and wind speed on the efficiency of a photovoltaic power plant: An experimental analysis

For each photovoltaic power plant, it is extremely important to perform an analysis of its efficiency, as well as an analysis of all parameters that may affect efficiency. The electric energy of the photovoltaic system, which is delivered to the electric power system on a daily basis, is determined through the average daily insolation, the surface of the panel and the average efficiency value. One of the parameters that affect the conversion efficiency of a photovoltaic power plant is a decrease in the conversion efficiency due to an increase in panel temperature. In this paper an example is a real photovoltaic power plant with a nominal power of 50 kW, which is installed on the rooftop of the building of the Institute "Mihajlo Pupin", located in Zvezdara forest, Belgrade, Serbia. The correlation analysis of the estimated temperature of the photovoltaic panel was performed using two models and the measured temperature of the photovoltaic panel. The temperature of the photovoltaic panel was estimated using models, one of which does not take into account, and the other takes into account the influence of wind speed on the temperature of the panel.

Comparison of modeled and measured photovoltaic microinstallation energy productivity

There are many models for determining the theoretical productivity of PV panels, based on weather data and data characterizing PV panels. The main target of this study to contribute the similar studies for Polish conditions for photovoltaic microinstallations. The study analyzed the compliance of weather data from the ERA5 database with the measurement (pyranometer on horizontal surface) on PV installation site. Comparative studies of insolation from the ERA5 model with measurements made with a pyranometer were carried out for 1187 days. Higher values for daily insolation values were observed in most day cases (85 %) for data from ERA5 than from the measuring station. The value of relative mean bias error (rMBE) was 23 %.The second part of the research concerned the verification of the computational model of PV energy production based on the data of photovoltaic panels, configuration of settings and locations as well as ERA5. The differences between the results from the model and the real measurements from the rMBE installation for the first year of operation are 8 % and for the second 0 %.

Insolation calculations of a photovoltaic power plant taking into account location-based and weather parameters

In this study, we set out to develop a methodology for calculating insolation of a photovoltaic power plant taking into account the maximum number of significant input parameters and its territorial adaptation. To this end, simulation modelling implemented in the MATLAB environment was used. Functional possibilities for the synthesis of models using existing elements with the integration of algorithms and modelling results between the blocks of the Simulink sub-system were used. In terms of significant input parameters, geographical coordinates, local time, tilt of the receiving solar panel, modelled day, atmospheric transparency coefficient, albedo and azimuthal angle were considered. A computer model of a photovoltaic power plant was developed for investigating the operation of photovoltaic cells depending on the coordinates of their installation, geometric parameters of solar panels, as well as the temperature and reflectivity of the environment. The performed modelling of the photovoltaic power plant operation visualised graphic dependences of insolation on the tilt of the solar panel, atmospheric transparency coefficient, geographical coordinates of the object and the current month or day. According to the analysis, 15 variations in the solar panel tilt modifies insolation by 10–15%, while variations in the atmospheric transparency coefficient result in 30–50% variations of insolation. As a result, the daily insolation values for the city of Angarsk throughout a year can be modified by 1000–6500 W/m2. The presented results of investigating a regionally adapted photovoltaic power plant demonstrated the need for accounting for location-based and weather parameters during the calculation of insolation for determining the applicability of a plant. The proposed mathematical model for calculating insolation of a photovoltaic power plant can be used for the design and optimization of power supply systems in combination with the specified photovoltaic solar power plants.

Potential effects of surface ozone on forests in Gangwon Province, South Korea, based on critical thresholds

High hourly concentrations of ozone, a secondary pollutant produced from the photochemical reactions of primary precursors, have been increasing in South Korea, bringing potential adverse effects on vegetation. Deforestation caused by high ozone concentrations has been investigated in China and Japan. Using ozone measurements from East and West, Gangwon Province, South Korea, from 2001 to 2018, this study compared changes in surface ozone concentrations and analyzed the influences of meteorological factors and air pollutants. This study calculated accumulated ozone exposure over a threshold of 40 ppb (AOT40) and investigated the possibility of ozone affecting deforestation. Monthly average surface ozone concentrations increased rapidly in both regions from 2009. Although the daily total insolation (a meteorological factor that significantly impacts photochemical reactions) of West Gangwon and East Gangwon did not differ significantly, the ozone concentration was lower in East Gangwon than in West Gangwon (1.5 times lower from 2001 to 2018) owing to local strong winds. Moreover, there was a negative correlation between nitrogen dioxide and ozone generation. AOT40 in West Gangwon was about twice that in East Gangwon and exceeded 10,000 ppbh, the critical level for forests, every year since 2003. Potential damage from high concentrations of ozone was higher in West Gangwon than in East Gangwon.

Associations of long-term solar insolation with specific depressive symptoms: Evidence from a prospective cohort study

Evidence suggests that sunlight counteracts depression, but the associations of long-term sunlight exposure with specific symptoms of depression are not well known. We evaluated symptom-specific associations of average 1-year solar insolation with DSM-5 depressive symptoms in a representative cohort of Finnish adults. The sample included 1,845 participants from the Cardiovascular Risk in Young Finns Study with data on DSM-5 depressive symptoms, place of residence and covariates. Daily recordings of global solar radiation were obtained from the Finnish Meteorological Institute. Each participant's residential zip code on each day one year prior to the assessment of depressive symptoms was linked to the solar radiation data, and 1-year average daily solar insolation was calculated. Associations of the average 1-year solar insolation with depressive symptoms were assessed with linear and logistic regression analyses adjusting for season, sex, age, as well as individual- and neighborhood-level socioeconomic characteristics. Average daily solar insolation over one year prior to the depressive symptom assessment was not associated with the total number of depressive symptoms reported by participants. In symptom-specific analyses, participants exposed to higher levels of solar insolation in their residential neighborhood were less likely to report suicidal thought (OR = 0.61, 95% CI, 0.39–0.94), and more likely to report changes in appetite (OR = 1.24, 95% CI, 1.00–1.54), changes in sleep (OR = 1.30, 95% CI, 1.06–1.59) and feelings of worthlessness/guilt (OR = 1.33, 95% CI = 1.07–1.65). These findings suggest that solar insolation may contribute to symptom-specific differences in depression. Studies in other populations residing in different geographical locations are needed.

Determination of the Appropriate Number of Photovoltaic Panels for Microgeneration and Self-supply of Final Consumers by Energy Production Estimation via Fuzzy Logic

A method is presented to determine the appropriate number of photovoltaic panels that should be installed in an end-user photovoltaic installation to guarantee the supply of energy to the load during the hours of solar radiation, according to factors such as the installation area and global solar radiation. Solar radiation is predicted by approximating the daily distribution of global irradiance through a Gaussian function, which is subsequently corrected using a heuristic approach. Meteorological parameters are used as input data such as the daily solar insolation and the maximum global irradiance for each day; this last parameter is obtained through an expert system based on fuzzy logic that was programmed and trained with the data of ambient temperature and relative humidity that were obtained in the processing stage. Output from this expert system is the predicted values of maximum radiation obtained for each day for a selectable time interval. With the predicted solar radiation, the generation of electrical energy from the photovoltaic panels is calculated. The load is randomly modeled from a pattern of the energy demand of the building to be powered by the photovoltaic system. The number of photovoltaic panels needed is found with the information acquired in the previous stages and the information of the energy demand of the load and the installation area. The results are the number of solar panels that would be needed at all hours of the day from which the radiation prediction was made.

Micro-electricity generation using solar thermal design and modelling thermosiphon applications from waste recycled materials

In this study, the abundant heat energy available from daily insolation in tropical climates is converted into DC current via a reversible thermoelectric effect. Recyclable components were employed in the construction of a simple solar-thermoelectric generator. The design used is based on the power tower method (without heliostats) of generating electricity from a steam-powered turbine. Recyclable waste materials such as soda can, insulation, support stand, (bottle tops) and plane mirrors were used. Integration of this TEG into a cogeneration system produced average steam temperature of 60 °C in 330 s, from concentrated Solar Power (CSP) from 720 plane mirrors over a land area of 4 m2. Steam emanating from the boiler was used to turn eight light weight bottle tops affixed to a rotor, under standard conditions of air mass of 1 atm. The thermo-electrical performance was determined from Z, figure of merit. Given that the electrical conductivity (σ), thermal conductivity (λ) and Seebeck coefficient of the thermo-power (S) of all materials used were assumed to be constant. The output energy directed through wires to a step-up transformer, generated an electromotive force which adequately lighted a 1.2 V light emitting diode.

Evaluation of atmosphere clearness and cloudiness parameters in the southern regions of Ukraine using statistical analysis

Introduction. This paper deals with the specific aspects of insolation of the terrestrial surface in the southern regions of Ukraine, namely the clearness index and diffuse fraction of the atmosphere. The study was based on satellite data of the average daily insolation and total cloudiness in the nodes of the two-degree grid for the domain with coordinates 48°-45° N and 29°-39° E for the period of 1981-2020. The purpose of article. The purpose was to develop statistic models of horizontal surface insolation for various locations of study domain. Main focus was put on special characteristics in conditions of fixed cloudiness. Satellite data for the summer season had been used to evaluate the maximum solar energy potential of Ukraine. Methods. Application statistical analysis and means of cartographic data layout were used in the paper. Results. It was found that with the highest (more than 50%) frequency the total cloud cover can be characterized by the atmosphere clarity corresponding to a clear sky condition. The significance of irradiation of the terrestrial surface with diffuse solar radiation has been observed, with the share of such radiation in the global irradiation (diffuse ratio) being closely inversely related to the clearness index (correlation about -0.97). In turn, both diffuse ratio and clearness index are statistically dependent on the sky clarity, that allowed deriving analytical functions - diffuse ratio and clearness index - of the sky clarity, which appeared to be S- and Z-shaped curves, respectively. Dispersion of the clearness index ( ) and the diffuse fraction ( ) values and the strength of their statistical relationship significantly depend on the sky clarity. The empirical distribution of the two-dimensional random variable ( ; ) well meets the Gaussian distribution, and the obtained dispersion ellipses allowed calculating the confidence intervals of the two-dimensional random variable (clearness index: diffuse fraction) for a given confidence level. The spatial distribution of the clearness index and diffuse fraction of the atmosphere in the southern regions of Ukraine revealed a significant dependence of these indices on the latitude and the type of underlying surface. At the end of the summer a seasonal effect has been observed in the spatial distribution of the clearness index and diffuse fraction, which can be explained by the specific seasonal features of atmospheric circulation, caused by the spreading out of the eastern ridge of the Azores anticyclone and the general situation with blocking developments in the Atlantic-European sector of the Northern Hemisphere. The scientific novelty. Correlation and regression models of special insolation characteristics in conditions of various cloudiness that are represented in this paper are new to Ukraine. Analysis of two-dimensional random value spread (clearness index: cloudiness index) allowed to assess probabilities of integral solar radiation flows. The obtained analytical membership functions for monthly average values of clearness and cloudiness indices depending on the level of sky clarity proved to be applicable for determining respective indices for daily time scale. Practical significance. The obtained results are important for comprehensive assessment of the solar / photovoltaic resources of southern regions of Ukraine. Specifically, analytical dependences have practical values for the purpose of forecasting direct and diffuse solar radiation in various time scales based on publically available global records of solar radiation.

Productivity and morphometric parameters of the microalga Dunaliella salina IBSS-2 under pilot cultivation in continental mid-latitude climate in spring

In this study, we aimed to investigate the taxonomy and various characteristics of Dunaliella salina IBSS-2 strain and describe its cultivation potential in mid-latitude climate during springtime. In addition, our analysis confirmed the essentiality of combining morphological, physiological, and other characteristics when identifying new species and strains of the genus Dunaliella, along with the molecular marker (internal transcribed spacer (ITS) of rDNA gene). The pilot cultivation of microalgae during the springtime in the south of Russia demonstrated that the climatic conditions of this region allow D. salina cultivation for biomass accumulation during this season, highlighting light and temperature conditions as the main factors determining the growth rate of D.salina. A two-fold increase in daily insolation and, consequently, in temperature in April resulted in a more than three-fold increase in productivity of D.salina culture. The maximum productivity of D. salina both in April and May was comparable and reached 2gm-2day-1, and the total yield for 8-10days was about 14.5-16gm-2. The additional CO2 supply into the D. salina culture did not show any significant effect on its growth rate; however, it contributed to maintaining the diversity of morphometric characteristics over a longer period of time. Changes in the morphological and morphometric characteristics of algal cells, including size reduction, were observed during the batch cultivation. Thus, the production potential of the green carotenogenic microalga D. salina was determined in the springtime, which allows expanding the seasonal interval of its cultivation in temperate latitudes.

Helheim Glacier diurnal velocity fluctuations driven by surface melt forcing

AbstractThe influence of surface melt on the flow of Greenland's largest outlet glaciers remains poorly known and in situ observations are few. We use field observations to link surface meltwater forcing to glacier-wide diurnal velocity variations on East Greenland's Helheim Glacier over two summer melt seasons. We observe diurnal variations in glacier speed that peak ~6.5 h after daily maximum insolation and extend from the terminus region to the equilibrium line. Both the amplitude of the diurnal speed variation and its sensitivity to daily melt are largest at the glacier terminus and decrease up-glacier, suggesting that the magnitude of the response is controlled not only by melt input volume and temporal variability, but also by background effective pressure, which approaches zero at the terminus. Our results provide evidence that basal lubrication by meltwater drives diurnal velocity variations at Greenland's marine-terminating glaciers in a similar manner to alpine glaciers and Greenland's land-terminating outlet glaciers.

Study case: cost-benefit of a photovoltaic system to reduce the consumption of the irrigation pumps in a Honduran sugar cane farm

This paper presents the results of the case study on the cost-benefit (B/C) of the implementation of a photovoltaic solar system on a sugar cane farm. “El Modelo’s” farm, electric pumping system represents an electricity consumption of 1,087.2 (MWh/year), which translates into an expense of the 19.7%. The study is based on three analyzes: market, technical, and financial. The market analysis represents the current demand profile, this profile shows that more than 70% of the energy is consumed during the insolation time. The technical analysis is based on the interpretation of meteorological data, such as the annual global radiation representing 1,800 (kWh/m2) and a daily insolation duration of approximately 8 hours; the design of a grid-connected photovoltaic system of 4,431 (m2), with an installed power of 474.2 (kW) and the comparison of its simulation of operation between Helioscope and PVsyst, which presents an annual power generation of 686.2 (MWh). The financial analysis has the purpose of calculating the B/C, for which a leveled cost of energy (LCOE) of 0.0425 ($/kWh) is calculated, thanks to this factor a projection of the current value of savings of $ 1,009,148.71 is established, which are compared with the current value of the initial investment costs of $ 555,603.44, these values are related to establish a B/C of 1.82, which assumed that this project is profitable.

Evaluating multiple parameters dependency of base temperature for heating degree-days in building energy prediction

To improve the prediction accuracy of heating demand, an appropriate base temperature should be estimated before using the heating degree-days (HDD) approach. This study collected the measured data for gas consumption at half-hourly resolution and the building physical characteristics from 89 educational buildings over four years. To determine the base temperature, in addition to the ambient temperature, more detailed independent variables, i.e. solar insolation, relative humidity, wind speed, and one-day ahead residual temperature, were incorporated into a three-parameter change-point multi-variable regression (3PH-MVR) for heating. The mean base temperature using the 3PH-MVR approach was about 0.4°C lower than the results from the 3PH method only. The relationships between base temperature and annual HDD (based on 15.5°C), building location, and mean daily solar insolation were evaluated. It is found that the annual HDD and the daily insolation had clear impacts on base temperature, while there was a plausible relationship between base temperature and building location. Compared with traditional approach, the proposed 3PH-MVR method considers multiple weather parameters and determines a more robust base temperature, thus improving the prediction accuracy of HDD with higher average R2 value at 0.86 than that of univariate regression (0.82).

Experimental investigation of suitable thin layer drying curve to solar maize dryer assisted for biomass back-up heater

A solar dryer assisted by biomass back-up heater was designed and manufactured from locally available materials to dry maize, and the drying model is selected, which better fits the dryer test results. This study tried to address the problem associated with the fact that solar dryers are efficiently operational only when there is sufficient solar energy. The dyer comprises a solar air heater, drying chamber, biomass back-up heater, and airflow systems. The solar heater has a length and width of 2 m × 1 m respectively and is enclosed with a transparent glass that allows the solar energy into the collector. The measurement taken to evaluate this dryer's performance is temperature, moisture content, solar irradiation, and airspeed. The average temperature difference between the ambient and the collector outlet was recorded as 9.6 °C, and 12.8 °C in the solar and biomass assisted dryer. The daily average solar insolation for the test periods of October and December at the site was 673 W/m2. When the system is loaded with 50 kg of wet maize grain at an initial moisture content of 21.3% and dried to 14.4% moisture content in 45 h drying time in the solar dryer, 4.03 kg of moisture is removed. A 50 kg of wet maize grain at an initial moisture content of 22.9% and dried to 14.2% moisture content in 27 h in solar dryer assisted by biomass back-up heater, 5.06 kg of moisture is removed. Solar dryer collector efficiency was estimated as 64.2% with an average drying rate of 0.0746 kg/hr. The solar dryer system efficiency was 20.8%, and solar assisted dryer efficiency was 4.3%.