Solar Altitude Research Articles

Near-surface heat transfer at two gentle slope sites with differing aspects, Qinghai-Tibet Plateau

The slope aspect effect is widely distributed on the Qinghai-Tibet Plateau and has an important impact on the permafrost environment. The differences in surface heat exchange characteristics of different slope aspects in the permafrost region of Gu Mountain in the Beiluhe Basin were compared and analyzed based on observations of the south slope (sunny slope) and north slope (shadowy slope) from 2019 to 2021. The air-ground heat transfer process on the slopes was simulated using the Monin-Obukhov similarity theory. Then, the simulation results of the sensible and latent heat fluxes on the slopes were corrected and analyzed using the Bowen ratio correction method. The results show that under the influence of the solar altitude angle and subsurface conditions, the downward shortwave radiation (DR), upward shortwave radiation (UR), and upward longwave radiation (ULR) were higher on the sunny slope than those on the shadowy slope, whereas the downward longwave radiation (DLR) was lower than that on the shadowy slope. Jointly, the net radiation energy on the sunny slope was smaller than that on the shadowy slope, and the annual average net radiation difference reached 16.7 W·m−2. The annual and daily variations in soil heat flux on the sunny slope were higher than those on the shadowy slope. The energy closure rate on the sunny slope was high with a confinement rate of 0.85, whereas that on the shadowy slope was poor with a confinement rate of 0.51. The air-ground energy transfer patterns on the sunny and shadowy slopes showed obvious seasonal differences. Both slopes are dominated by the sensible heat exchange transfer mode in the cold season, whereas the shadowy slope is dominated by latent heat exchange in the warm season. This study improves our understanding of the distribution, development, and environmental effects of permafrost, under the influence of local factors.

Sky polarization pattern under multi-layer environment of atmosphere and sea fog

The vertical polarization distribution pattern of sea fog multilayer media and skylight in the atmosphere is explored. To change the complicated maritime environment, the simplified double layer structure of the atmosphere and sea fog is employed, and the scattering coefficients of the uniform atmosphere and sea fog medium are derived using the Rayleigh and Mie scattering methods, respectively. Using the adding-doubling method (RT3) based on the vector radiation transmission equation, the transmission of radiation between the two layers of the medium is calculated to obtain the polarization distribution conditions of skylight, and the variation tendency of the polarization characteristics observed from the ground is studied for the downwelling radiation of sea fog on the meridian of the Sun. An indoor sea fog setting was employed to perform the polarization transmission test, and the relationship between humidity, light intensity transmittance, and polarization degree was explored. The data suggest that the Sun’s position gives the lowest degree of polarization (DOP), and that the maximum value is obtained when the angle between the solar altitude angle and the observed altitude angle is 90°. Short wavelength lasers have a higher influence on optical transmittance than long wavelength lasers do when humidity levels increase. The circular polarization effect of long wavelength laser is better in damp surroundings.

Desert Soil Salinity Inversion Models Based on Field In Situ Spectroscopy in Southern Xinjiang, China

Soil salinization is prominent environmental issue in arid and semi-arid regions, such as Xinjiang in Northwest China. Salinization severely restricts economic and agricultural development and would lead to ecosystem degradation. Finding a method of rapidly and accurately determining soil salinity (SS) is one of the main challenges in salinity evaluation, saline soil development, and utilization. In situ visible and near infrared (Vis-NIR) spectroscopy has proven to be a promising technique for detecting soil properties since it can realize real-time, rapid detection of SS. However, it still remains challenging whether Vis-NIR in situ spectroscopy can invert SS with high accuracy due to the interference of environmental factors (e.g., light, water vapor, solar altitude angle, etc.) on the spectral in the field. To fill this knowledge gap, we collected Vis-NIR in situ spectral and lab-measured SS data from 135 surface soil samples in the Kongterik Pasture Nature Reserve (KPNR) in the desert oasis ecotone of southern Xinjiang, China. We used genetic algorithm (GA), particle swarm optimization (PSO), and simulated annealing (SA) algorithms to select the feature bands of SS. Subsequently, we combined extreme learning machines (ELM), back-propagation neural networks (BPNN), and convolutional neural networks (CNN) to build inversion models of SS. The results showed that different feature bands selection methods could improve the Vis-NIR in situ spectral prediction model accuracy. Either SS inversion models were built using full-band spectral data or feature-band spectral data. Compared with the full-band (401–2400 nm) spectral modeling, the validation set R2 of ELM, BPNN, and CNN models built selected feature bands selected by PSO, GA, and SA, respectively, were improved by more than 0.06. The accuracy of predicting SS varied widely among modeling methods. The accuracy of CNN model was obviously higher than that of BPNN and ELM models. The optimal hybrid model for predicting SS constructed in this study is SA-CNN model (R2 = 0.79, RMSE = 9.41 g kg−1, RPD = 1.81, RPIQ = 2.37). This study showed that the spectral feature bands selection methods can reduce the influence of environmental factors on in situ spectroscopy and significantly enhance the inversion accuracy of SS. The present study provided that estimating SS using in situ Vis-NIR spectral is feasible.

Solar Radiation Characteristics in Shanghai

Based on the solar radiation and meteorological data of five meteorological stations of Baoshan, Chongming, Minhang, Fengxian, and Songjiang meteorological stations in Shanghai from 1982 to 2021, the suitable climatological formula for calculating solar radiation in the Shanghai area was selected as Qg = Qt (a+bS) by applying the climatological calculation principle of total solar radiation. The empirical coefficients for each month of the equations were fitted using the least squares method based on the total radiation and sunshine percentages for each month of the calendar year at five meteorological stations. The results show that the average total radiation of Shanghai in 1982-2021 is 4688.69 MJ/m2, among which the total radiation is the most in May, the least in January and December, and although the noon solar altitude angle is the largest in June and July, the total radiation is less than in May and August due to the new influence of the rainy season sky shading than in May. Due to the small area of the Shanghai region, the difference in total solar radiation between the five stations for each month is insignificant. In terms of the spatial distribution of total solar radiation, the northeastern and coastal areas of Shanghai have the most, and the Baoshan area has relatively less; the northern part has the most in spring; the coastal area has the most in summer; the spatial distribution of total solar radiation in winter and autumn is similar, both having the least in the northeast.

Pedestrian safety at urban intersections: lighting conditions is the question

Sustainable and livable cities and non-motorized transportation modes are being increasingly promoted around the world. A considerable number of studies have investigated various factors associated with the severity of pedestrian crashes. However, little attention has been paid to the particular impacts of lighting conditions. This paper aims to differentiate between different lighting conditions based on solar altitude by developing separate Generalized Ordered Probit (GOP) models for the four distinct lighting conditions (i.e. daylight, twilight, dark, and lighted) analysing pedestrian injury severity at urban intersections. The models are tested using a set of log-likelihood ratio tests, which show there are key differences in the significance of the estimates, magnitude, and even the direction of the effects of explanatory variables, in which such differences may not be revealed by calibrating one aggregate model. Notably, built environments, age, gender of both pedestrian and driver, and speed limits were found to have different impacts on the severity of the crash.

Empirically testing the influence of light regime on diel activity patterns in a marine predator reveals complex interacting factors shaping behaviour

Abstract Diel cycles in marine predator diving behaviour centre around the light‐mediated diel vertical migration (DVM) of prey, and are considered critical for optimizing foraging and limiting competition across global seascapes. Yet, our understanding of predator diel behaviour is based primarily on examining relative depth usage between constant day/night cycles with no formal investigation of how varying light regimes interact with abiotic factors to shape diel activity. The extreme seasonal light regimes (midnight sun, polar night, day/night cycle) in the Arctic provide a unique natural experimental setting to empirically investigate the occurrence and intensity of diel behaviour in marine predators relative to changing light levels while concomitantly assessing interacting abiotic factors. Depth time series data from satellite‐linked tags deployed on six beluga whales (Delphinapterus leucas) for up to 12 months were used to quantify diel behaviour by calculating dissimilarity in time‐at‐depth between periods of low and high solar altitude on each day. Generalized additive mixed effects models were used to examine the influence of hours of daylight across extreme light cycles, coupled with bathymetry and sea ice concentration; focal diel patterns were further examined relative to the thermal structure of the water column. As predicted, belugas exhibited cathemerality during the midnight sun, and initiated diel behaviour with the onset of the fall day/night cycle, with a marked increase in its intensity with the progression to equal day/night length. Occurrence of diel patterns, however, was complex; ceasing in regions with seafloor depths <700 m, and occurring with greatest intensity when the water column was thermally homogeneous within the upper 150 m. Through empirical investigation, this study demonstrates that the onset of day/night light cycles and presumably associated prey DVM can modulate predator diel dive behaviour under certain circumstances, but highlights how the complex interaction of abiotic factors with light regime shape dynamic spatiotemporal patterns. These findings, building on a body of recent work, emphasize that the traditional view of the ubiquitous occurrence of diel behaviour tied to DVM at the base of the food web oversimplifies vertical predator–prey interactions, identifying the need for more structured investigation. Read the free Plain Language Summary for this article on the Journal blog.

Performance investigation of SUNTRAP module for different locations: An energy and exergy analysis

Concentrating Photovoltaic/Thermal (CPV/T) systems can harness the freely available solar energy to simultaneously generate electricity and sensible heat. Using the principles of optical concentration, they can generate more electrical energy per unit area of solar cells and provide a better quality of thermal energy. In this work, we have developed an analytical model to simulate and predict the performance of a dense array hybrid CPV/T collector called “SUNTRAP.” The concentration of incident radiation is achieved using a reflective type three-dimensional cross-compound parabolic concentrator (3DCCPC) with a geometric concentration ratio of 3.6 × . The extraction of heat from the solar cells is achieved by allowing water to flow through the copper cooling duct on which the solar cells with CCPC are bonded. Using previously developed algorithms, the optical efficiency of the CCPC is calculated as a function of solar azimuth and altitude angle. The obtained optical efficiency is coupled to the thermal model to obtain the temperature distribution in the collector. The numerical results are in good agreement with the experimental measurements obtained at the outdoor solar laboratory at Penryn Campus, Cornwall. The average deviation in outlet water temperature between the numerical and experimental ones is 1.9%. The total electrical and thermal energy obtained from the CCPC-PV/T module on an experimental day is 1.21 kWh/m2 and 46.46 kWh/m2. A parametric study was done to obtain the effect of flow rate and external wind velocity on the performance of the collector. The solar cell temperature is found to decrease with an increasing flow rate. The performance prediction of the CCPC-PV/T module at Penryn shows that the module produced maximum energy in August, producing 7.51 kWh/m2 of useful energy. An economic analysis was performed to obtain the Levelized cost of electricity (LCOE) that the CCPC-PV/T module can deliver, and the LCOE was found to be £1.08/kWh. The coupled model is also utilised to predict the performance of the system for five different geographical locations, including Chennai, Rome, Alice Springs, Montreal, and Barrow. The model considers optimum panel tilt and time-dependent optical efficiency of the concentrator while estimating the energy output. Based on the results, the overall performance of the collector was found to be good in Chennai, with an annual electrical energy gain of 51.95 kWh/m2 and an annual thermal energy gain of 1164 kWh/m2.

Association of Altitude and Solar Radiation to Understand Coffee Quality

The consumer market has a strong tendency to consume specialty coffees, making it essential to understand the influence of environmental conditions, such as solar radiation and altitude, on coffee quality. This study aimed to analyze the physical and sensory quality of Arabica coffee as a function of different altitudes and incident solar radiation on the coffee tree. The study was carried out in the city of Manhuaçu-MG, Brazil. Three altitudes (950, 1050 and 1150 m above mean sea level) and two sides of coffee exposure to solar radiation (east face: morning sun and west face: afternoon sun) were studied in two post-harvest processing (natural and peeled cherry). Sensory attributes, granulometry and occurrence of coffee defects were evaluated, in order to verify if there was variation in the physical and sensorial characteristics of the coffee. It was found that at an altitude of 1150mamsl, on the exposed face of the plant that received the afternoon sun, there was the formation of better-quality coffee, when compared to the face that received the morning sun. On the other hand, at lower altitudes, coffees from the face of the plant exposed to the morning sun showed a greater association with physical and sensory quality parameters.

Power Controller for Dual-axis Solar Tracking System using PID

Solar energy is one of the rich and unlimited energy sources in Malaysia which can generate power instead of the burning of fossil fuels which can cause air pollution. In this study, a dual-axis solar tracking system is proposed to improve the harvested power. To encourage the maximum output power is produced, PID controller is used. Its function is to achieve the reference power where the angle of the horizontal and vertical axes is considered. The solar radiation is studied from 7 a.m. (0700) to 5 p.m. (1700) according to the habit of solar altitude angle and the azimuth angle in Perlis, Malaysia. There is two PID controllers are developed for the orientation and inclination axis of the solar tracker. The output power between the dual-axis and single-axis of solar tracking system are compared through the simulation in MATLAB Simulink. In conclusion, the dual-axis solar tracker has a better performance than the single-axis solar tracker due to the higher degree of freedom to follow the motion of sun. This maximum power can keep going to the reference power of the photovoltaic module during the greatest radiation of sun depending on the solar altitude and azimuth angle.

Temporal variation and influencing factors of albedo in a deciduous broad-leaved forest

In situ measurement of albedo is important for estimating ecosystem energy budget and its remote sensing application. However, the measurement method of albedo on sloping land is limited and the difference in temporal variation in albedo between visible and near-infrared bands remains unclear. Taking a deciduous broad-leaved forest at the Maoershan Forest Ecological Station in Northeast China as an example, we explored the temporal variation and influencing factors of albedo for three bands: incident and reflected solar radiation (SR, 300-2800 nm), photosynthetically active radiation (PAR, 400-700 nm), and near infrared radiation (NIR, 700-2800 nm). The temporal difference in albedo measurements between the two installation methods of radiometers was analyzed. The results showed that, in sunny days, the diurnal variation in SR and NIR albedo had an asymmetric U-shaped curve around the local noon, while PAR increased from sunrise to sunset. In cloudy days, the albedo decreased sharply and then tended to be stable. The measurement with parallel sensors to the slope increased the daily mean value of albedo, but reduced the daily asymmetry of SR and NIR. For the whole growing season, the maximum albedos of SR, NIR and PAR in horizontal measurement were 0.16, 0.27 and 0.11, respectively, and the minimums were 0.07, 0.11 and 0.03, respectively. Albedo in the SR and NIR wavebands increased first and then decreased (the peak value was in July), while PAR showed a contrasting pattern. SR albedo was mainly controlled by NIR rather than PAR. The contribution of the influencing factors was ranked in the order of normalized difference vegetation index (61.7%-78.5%, representing leaf area index) > solar altitude angle (15.4%-36.9%) > clearness index (0.4%-36.9%).

Study on natural lighting and electrical performance of louvered photovoltaic windows in hot summer and cold winter areas

Building integration with photovoltaics has received more and more attention in the development of green buildings. But traditional photovoltaic windows cannot make monthly adjustments to changes in solar altitude and weather. This paper proposes a new type of photovoltaic shutter system, the inclination angle and spacing of which can be adjusted according to the solar altitude angle and weather in different months. In order to better study the natural lighting quality and photoelectric conversion characteristics, this paper builds an experimental test platform for louvered photovoltaic windows. The final results of Illuminance of experiment and simulation are consistent. Furthermore, a new daylighting index is innovatively proposed, which compared to the general annual statistical indicators that are not precise enough. Combined with the typical weather in the area with hot summer and cold winter, the monthly angle and spacing regulation strategy is optimized. The research results show that compared with the change of the inclination angle, the change of the spacing makes the change of indoor lighting and electricity revenue more obvious. The months before and after June are the months with the lowest electric energy and the best indoor lighting quality of louvered photovoltaic windows. Its electricity revenue is between 9.18 and 22.46 kWh, and the proportion of indoor space that meets the 450–2000 lx illuminance range and the daylighting time exceeds 50% is about 85%. The months with higher electricity revenues are around March and October, with revenues ranging from 14.11 to 53.04 kWh.

Experimental characterization of the thermal performance of the Haines 2 solar cooker

This work presents the most exhaustive experimental characterization of the thermal performance of the Haines 2 solar cooker available to date. Two Haines 2 solar cookers were tested side-by-side in Malaga, Spain, 36.7°N, between May 2021 and December 2021. A novel test procedure using empty pots and a tilted plane with variable inclination gave useful information about the influence of the solar altitude angle on cooker performance, and allowed identification of the best range for each of the two available reflector configurations for this cooker. Some suggestions are given to improve the cooker design for low solar altitude angles. In addition, a large number of water heating tests partly based on the ASAE S580.1 standard protocol were conducted to i) determine the standardised power, ii) examine the influence of the solar altitude angle, and iii) investigate the impact of using partial loads. All these results provide a complete characterization of the performance of this cooker in a wide range of operating conditions of practical interest. It is recommended that future versions of ASAE S580.1 standard consider the influence of both solar altitude angle and partial loads.

A beam-down solar concentrator with a fixed focus — Design and performance analysis

In this study, a two-stage beam-down dish solar concentrator with a fixed focus was innovatively designed, consisting of a paraboloidal primary reflector (PR), a flat secondary reflector (SR), and a receiver. A new sun-tracking mode was proposed to obtain a fixed focus. The influences of the PR rim angle, SR tilt angle, and distance from the SR to the primary focus on the concentration ratio and optical efficiency using different types of SR (flat or hyperboloidal reflectors) were comprehensively investigated. The instantaneous and overall optical performances were determined using Monte Carlo ray-tracing simulations. The results showed that the optimum SR tilt angle is equal to 38.25° as the solar altitude angle ranges from 30° to 73.5°, and the optimum PR rim angles are 45° and 60° for the two proposed concentrators adopting a flat SR (Design I) and a hyperboloidal SR (Design II). The numerical values of instantaneous and overall optical performance for Design I and Design II are almost equal, whereas the flat SR adopted in Design I is preferred in terms of manufacturing accuracy and installation. A peak solar concentration ratio of 6970 suns and an overall average of 2097 suns are achieved over the 35 mm-radius aperture of the receiver for Design I. The radiative power and overall optical efficiency are 8.089 KW and 78.9%, respectively.

Incorrect categorisation of ambient light level at the time of a road traffic collision

Ambient light level, one of the items recorded by police investigating a road traffic collision (RTC) was previously suggested to be incorrectly recorded in 5%–15% of cases. Significant erroneous categorisation of ambient light level, as suggested by the latter estimate, may lead to incorrect conclusions being drawn about the impact of light on RTCs which is critical where such data inform transport policy decisions. This study investigated the accuracy with which ambient light level was recorded in comparison to that determined using solar altitude at the time, date and location of the RTC. Data were drawn from the STATS19 database of RTCs in the UK for the period 2005 to 2015. Ambient light level was incorrectly reported in 103 021 (5.79%) of the 1 779 903 RTCs in that period. The percentage of errors was greater for RTCs occurring after dark than in daylight, and for RTCs where the scene was not attended by a police officer than those that were attended: ambient light level was incorrectly categorized in 8.72% unattended RTCs in darkness. The highest percentage of errors (57%) occurred within civil twilight; if these are omitted the overall percentage reduces to 2.81%, a similar error rate to that available for the determination of RTC location.

Numerical Simulation of Soil Temperature With Sand Mulching During the Growing Season of Spring Wheat

The thermal conditions of soil are important in practical agricultural production. The characteristics of heat flux, moisture content, thermal conductivity, and other soil parameters vary with temperature. This study uses VADOSE/W to create a model of heat transmission between soil and atmosphere, simulating daily changes in soil temperature using sand mulching. By using the published data to verify the model, the results show that the fitting effect is good and the reliability of the model is verified. We also used this model to determine the temporal and spatial distributions of soil temperature, temperature differences, and a temperature gradient for sand mulching and bare soil during the growing season of spring wheat. These results indicated that the sand mulching preserved heat at night. The difference in temperature at each depth and the temperature gradient became negative with the gradual increase in solar altitude. The difference in soil temperature at each depth and the temperature gradient tended to become positive by 22:00. These results indicated that the sand mulch effectively maintained the soil temperature in the morning and night during the growing season and impeded the transfer of heat at mid-day. This study provides a new method for determining the transfer of heat in sand-mulched soil, which can guide the effective regulation of soil temperature.

Summer performance of a naturally ventilated double-skin facade with adjustable glazed louvers for building energy retrofitting

Facade energy retrofitting marks an important step toward a low-carbon building industry. As a high-performance building envelope, the double-skin facade is increasingly applied to existing buildings with proven effectiveness. To improve energy efficiency and solve the lingering overheating problems in summer, a new type of double-skin façade (DSF) integrated with adjustable glazed louvers is proposed. Experimental investigations were conducted in a Chinese city with a typical temperate continental climate, covering basic configurations, thermal optimizations, operation strategies, and energy performance. The study demonstrated that cavity ventilated and interior ventilated configurations perform best during daytime and nighttime, respectively. The open configuration of the external skin improved the daytime cavity ventilation by leveraging wind pressure instead of thermal buoyancy. It also allowed cavity height to be lowered, giving DSF the prospect of application to buildings with low floor-to-floor height. While tilted louvers reduced cavity ventilation, they avoided reflecting sunlight into the room and gaining heat. The tilt angle proposed is equal to the noon solar altitude angle in late summer. During the nighttime, the louver skin significantly improved indoor ventilation, but a reasonable way to open internal windows is also needed. Additionally, switching between different configurations based on the dynamic, localized temperature thresholds maximized climate responsiveness and indoor comfort while minimizing cooling loads. Compared with the conventional design, the optimized louver-type DSF delivered significant energy savings of 11.9% and 5% in summer, daytime and nighttime, respectively, successfully reducing the overheating risks.

Temporal and Spatial Characteristics of the Global Skylight Polarization Vector Field

There are two widely recognized global fields in nature: the gravity field and the geomagnetic field. Universal gravitation and Earth rotation are important sources of the Earth’s gravity and geomagnetic fields, which are well known to us. After years of long-term observation, global research, and analysis, it was discovered that we have neglected a direct incident energy of the universe on the Earth. Solar radiation, leading to energy exchange from the atmosphere 100 km above the land surface, is the energy source of the Earth. Polarization is one of the four basic physical properties of solar radiation. After the solar radiation reaches the surface of these media, it reflects, scatters or refracts, and exhibits different degrees of polarization. The polarized solar light forms the Earth–sky polarization vector field. The polarized light dispersion is expected to become a new method for global analysis of the human environment. Polarization detection is the best way to accurately explore the atmospheric effects. Local polarized skylight distribution was found in different sites in the world; however, the global distribution of the polarized sunlight radiation has never been explored. In this paper, we investigate the Global Skylight Polarization Field. This study aimed at providing new insight into the laws of polarization over our Earth. We use a Rayleigh scattering model to obtain the simulation results of the sky polarization field. Rayleigh scattering occurs when the particle size is much smaller than the wavelength of the incident electromagnetic wave. We also use a polarized fisheye camera to collect the sky polarization image and calculate the distribution pattern of the DOLP (degree of linear polarization) and AOLP (azimuth of linear polarization) of the skylight. The stability and gradual change in the degree of polarization in the zenith direction are verified, and the distribution law and daily change law of the degree of polarization in the sky are obtained. With the increase in the solar altitude angle, the degree of polarization will decrease. We also observed the skylight polarization in different weather conditions. Our results demonstrate the physical basis, characteristics, and usability of the polarization field. They show an inevitable trend from optical remote sensing to polarization remote sensing.

A Study on Daylighting Performance of Split Louver with Simplified Parametric Control

A split louver consists of two sections with their slat angles to be adjusted separately for glare protection and redirection of sunlight, respectively. The upper section works in conjunction with the lower section to enhance daylight availability and uniformity throughout the year. The study aims to improve the daylighting performance of the split louver by applying a simplified parametric control, which predetermines the angle difference between adjacent slats in the upper section for a chosen solar altitude and then keeps this difference fixed during operation. The slats in the upper section can be changed parametrically using the Grasshopper to reflect daylight onto the ceiling and then illuminate the rear zone of a space. The lower section of the split louver can control the daylight in the front space area and may affect the amount of light in the back. The performance indicator in evaluating the proposed split louver design for the chosen typical days is the percentage coverage of the work plane area for the illuminance range of 150~750 lux, which was achieved up to 100% in some cases. The proposed split louver with the simplified parametric control has the potential to provide relatively consistent and distributed daylight coverage of the floor area and a glare-free environment.

Solar Cycle and Seasonal Variability of Martian Ionospheric Irregularities from Mars Atmosphere and Volatile Evolution Observations

Spacecraft observations around Mars show that ionospheric irregularities occur frequently in the Martian ionosphere. In this study, Mars Atmosphere and Volatile Evolution data (the region is below ∼200 km) during 2015 January to 2021 March were used to revisit the statistical characteristics of ionospheric irregularities and the comparison of irregularities in Martian years with higher or lower solar activity phase of solar cycle. Results show that the characteristics of the irregularities with a larger length scale associated with the magnetic field and solar zenith angle are similar to the previous studies. Moreover, our results show that the occurrence rate of irregularities exhibits dawn and dusk asymmetry, and the occurrence rate at dusk is higher than that at dawn. In addition, results demonstrate that the occurrence rate of irregularities is higher in Martian years with higher solar activity than Martian years with lower solar activity, which means that the solar cycle might play an important role in the formation of irregularity events. Further studies show that the solar zenith angle (SZA) and altitude at the maximum occurrence rate depend on the level of solar activity. The SZA and altitude of the maximum occurrence rate are smaller in the Martian year with higher solar activity than the lower. We also found that the rate of events is lower during the day than the terminator in the ionospheric dynamo region. By contrast, in the regions where both electrons and ions are magnetized, events have a higher rate during the day than the terminator. Furthermore, the seasonal variation of the irregularity events was also presented in this study. Results show that the occurrence rate in the dynamo region with 80° < SZA < 150° in MY34 and MY35 show an incremental trend from spring to winter, but this trend is not obvious in MY33.

Investigation for Performance Comparison of Solar Tracking System with Static Solar System

Around the world, sun oriented force has become the third greatest wellspring of vitality after hydro and twist, in this manner, grabbing a worldwide eye. This investigation draws a correlation between the presentation of Solar Tracker and Static Solar System or a nearby planetary group with fixed pivot to evaluate the sunlight based force. By utilizing different sun points, for example, peak, sunlight based elevation, and solar altitude, sun powered irradiance was determined during a day either shady or radiant, while the aggregate vitality created during the entire month was additionally estimated. In addition, for a more clear understanding, proficiency contrasts during a day just as during the entire month were considered as well. The outcomes of simulations show that implementing the sun tracker concept can increase the efficiency of a solar PV system. It has been determined that by implementing the azimuthally tracking system and the elevated tracking system, PV system efficiency is increased by 37% and 12%, respectively.