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The Effect of Light Intensity and Temperature on Flowering and Morphology of Potted Red Firespike
摘要： Red ?respike (Odontonema strictum) is a tropical ?owering plant that was selected as a potential ?owering potted plant for its attractive red ?oral spikes. The objective of this study was to evaluate how light intensity, photoperiod, and temperature affect the growth and ?owering of ?respike. In Experiment 1, plants were grown under 0%, 45%, or 65% shade and two photoperiod conditions; long-day (LD = ≥14 h) and short-day (SD = 9 h), for 16 weeks. Plants grown under 45% shade + LD were tallest at 35.9 cm, while plants grown under 65% shade + SD were shortest at 22.8 cm. During the ?nishing stage, the number of in?orescences increased when plants were grown under 45% shade + SD, 45% shade + LD, and no shade, with 6, 7, and 9 in?orescences, respectively. In addition, the ?rst open ?ower was observed in the 0% shade group (control) 92 days after starting the experiment. The time to ?rst open ?ower increased when the plants were grown under 65% shade, either under SD or LD. In Experiment 2, plants were grown in controlled environment growth chambers with average daily temperatures of 15, 25, or 35 ?C and an irradiance of 200 μmol·m?2·s?1 for 9 h per day. Plants grown at 25 ?C were the tallest and had the largest leaf area. Plants grown at 15 and 35 ?C had 28% and 22% less leaf area, respectively. The average number of in?orescences in plants grown at 25 ?C was 1.6, while no in?orescence development was observed in plants grown at 15 or 35 ?C by the termination of the experiment. There were no differences between plant growth index or branch number in response to temperature. Under the experimental conditions tested, the most rapid and uniform ?owering of ?respike occurred when plants were grown under no shade or at 25 ?C.
关键词： shade,irradiance,Odontonema strictum,photoperiod,short-day
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE PES Asia-Pacific Power and Energy Engineering Conference (APPEEC) - Kota Kinabalu, Malaysia (2018.10.7-2018.10.10)] 2018 IEEE PES Asia-Pacific Power and Energy Engineering Conference (APPEEC) - Mitigating the effect of partial shading by triple-tied configuration of PV modules
摘要： Partial shading is the phenomenon, which occurs when PV modules receive irregular irradiance on a PV array. Due to that, shaded PV modules are bypassed by diodes and significant reduction in power is experienced. To counter such problem, PV modules are connected in different configuration to provide alternative path for current to flow, so that the effect of partial shading is lessened and power attainment is improved. A comprehensive literature review suggests that several PV configurations are proposed namely simple-series (SS), parallel (P), series-parallel (SP), total-cross-tied (TCT), bridge-linked (BL) and honey-comb (HC). In this paper, a comprehensive review is presented to highlight the benefits and limitations of each scheme. To mitigate the limitation of other approaches, a new configuration named triple-tied (TT) is proposed. Several experiments are carried out using both MATLAB Simulink and hardware implementation to validate the performance of proposed configuration. Eleven different partial shading cases are used to analyze the output characteristics. Based on the results, the proposed TT configuration outperforms other PV configurations except TCT. However, in TT wiring connections are significantly reduced compared to TCT which makes it favorable in many large-scale PV applications.
关键词： PV Configuration,Maximum Power,Partial Shading,Solar,PV,Irradiance Mismatch
更新于2025-09-04 15:30:14
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Preliminary assessment of two spatio-temporal forecasting technics for hourly satellite-derived irradiance in a complex meteorological context
摘要： This paper examines two spatio-temporal approaches for short-term forecasting of global horizontal irradiance using gridded satellite-derived irradiances as experimental support. The first approach is a spatio-temporal vector autoregressive (STVAR) model combined with a statistical process for optimum selection of input variables. The second is an existing operational cloud motion vector (CMV) model. An evaluation of the predictive performance of these models is presented for a case study area in the Caribbean Islands. This region is characterized by a large diversity of microclimates and land/sea contrasts, creating a challenging solar forecasting context. Using scaled persistence as a reference, we benchmark the performance of the two spatio-temporal models over an extended 220 × 220 km domain, and for three specific, climatically distinct locations within this domain. We also assess the influence of intra-day solar resource variability on model performance. Finally, we present preliminary evidence that a blend of CMV and STVAR forecasts leads to improved accuracy under all conditions.
关键词： Cloud motion vector,Spatio-temporal forecasting,Satellite-derived irradiance,Complex meteorological context
更新于2025-09-04 15:30:14
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Influence of Cosine Corrector and Uas Platform Dynamics on Airborne Spectral Irradiance Measurements
摘要： Measuring solar-induced chlorophyll fluorescence from small-sized Unmanned Aircraft Systems (UAS) can potentially fill the scaling gap between ground-based and airborne/space-borne observations. These measurements require well calibrated, high-spectral resolution spectroradiometers and precise measurements of vegetation radiance and incoming solar irradiance. Here we present a system equipped with a spectroradiometer with a split optical path that measures incoming irradiance through a cosine corrector/diffuser. The objectives of this study are to characterise cosine corrected solar irradiance measurements with regard to sensor homogeneity and possible offset from an ideal cosine response. We further suggest a methodology to calculate a corrected zenith angle that accounts for changing sensor orientation due to pitch, roll and heading of the UAS platform during flight. We found that the cosine corrector is sufficiently homogeneous, thus measurements are independent of UAS heading. The response follows the cosine law for zenith angles, however, the sensor significantly underestimated irradiance for zenith angles >10?, with overall cosine errors ranging from 0.991 to 1.229. Yet, typical in-flight platform pitch and roll angles produce a zenith angle offset of up to 6? in low wind conditions. Cosine sensor measurements corrected for the zenith angle offset and the cosine error resulted in a 1.7% change in irradiance.
关键词： irradiance cosine corrector,spectroradiometer,sun zenith angle,solar-induced chlorophyll fluorescence,unmanned aircraft system
更新于2025-09-04 15:30:14
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Identification of photospheric activity features from SOHO/MDI data using the ASAP tool
摘要： The variation of solar irradiance is one of the natural forcing mechanisms of the terrestrial climate. Hence, the time-dependent solar irradiance is an important input parameter for climate modelling. The solar surface magnetic field is a powerful proxy for solar irradiance reconstruction. The analyses of data obtained with the Michelson Doppler Imager (MDI) on board the SOHO mission are therefore useful for the identification of solar surface magnetic features to be used in solar irradiance reconstruction models. However, there is still a need for automated technologies that would enable the identification of solar activity features from large databases. To achieve this we present a series of enhanced segmentation algorithms developed to detect and calculate the area coverages of specific magnetic features from MDI intensitygrams and magnetograms. These algorithms are part of the Automated Solar Activity Prediction (ASAP) tool. The segmentation algorithms allow us to identify the areas on the solar disk covered by magnetic elements inside and outside boundaries of active regions. Depending on their contrast properties, magnetic features within an active region boundary are classified as sunspot umbra and penumbra, or faculae. Outside an active region boundary magnetic elements are identified as network. We present the detailed steps involved in the segmentation process and provide the area coverages of the segmented MDI intensitygrams and magnetograms. The feature segmentation was carried out on daily intensitygrams and magnetograms from April 21, 1996 to April 11, 2011. This offers an exciting opportunity to undertake further investigations that benefit from solar features segmentations, such as solar irradiance reconstruction, which we plan to investigate in the future.
关键词： Magnetogram,Sunspot,Solar image processing,Spectral irradiance,Active region
更新于2025-09-04 15:30:14
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Light penetration in seawater polluted by dispersed oil: results of radiative transfer modelling
摘要： The downwelling light in seawater is shaped by natural seawater constituents as well as by some external substances which can occur locally and temporally. In this study we focused on dispersed oil droplets which can be found in seawater after an oil spill or in the consequence of intensive shipping, oil extraction and transportation. We applied our modi?ed radiative transfer model based on Monte Carlo code to evaluate the magnitude of potential in?uence of dispersed oil droplets on the downwelling irradiance and the depth of the euphotic zone. Our model was validated on the basis of in situ measurements for natural (unpolluted) seawater in the Southern Baltic Sea, resulting in less than 5% uncertainty. The optical properties of dispersed Petrobaltic crude oil were calculated on the basis of Mie theory and involved into radiative transfer model. We found that the changes in downwelling light caused by dispersed oil depend on several factors such as oil droplet concentration, size distribution, and the penetration depth (i.e. vertical range of oil droplets occurrence below sea surface). Petrobaltic oil droplets of submicron sizes and penetration depth of 5 m showed a potentially detectable reduction in the depth of the euphotic zone of 5.5% at the concentration of only 10 ppb. Micrometer-sized droplets needed 10 times higher concentration to give a similar effect. Our radiative transfer model provided data to analyse and discuss the in?uence of each factor separately. This study contributes to the understanding of the change in visible light penetration in seawater affected by dispersed oil.
关键词： radiative transfer,droplet size distribution,dispersed oil,Oil pollution,downwelling irradiance
更新于2025-09-04 15:30:14
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Comparison of Bifacial Solar Irradiance Model Predictions With Field Validation
摘要： Models predicting rear irradiance for bifacial systems are critical to establish accurate estimates of energy yield. Here, we compare five published bifacial irradiance models, varying clearance, row spacing, tilt, and albedo to measure the sensitivity to these parameters. Bifacial energy gains (BGE) as high as 20% are predicted for some configurations. Model agreement is generally good for low ground clearance (clearance heights lower than 0.75 times the collector width), but at higher clearances, finite system size and edge effects become a significant factor in simulations, stretching assumptions of infinite system extent made in some models. In addition, rear irradiance uniformity is improved at high ground clearance, as expected. A test-bed construction and results are described for comparison between modeled and measured data in Golden, CO, USA. The investigations indicate that model agreement for BGE calculation is better than 2% (absolute) when compared with measured results, depending on the system configuration.
关键词： photovoltaic (PV) system modeling,Bifacial solar panels,irradiance modeling
更新于2025-09-04 15:30:14
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Modeling and Simulation of High-Frequency Solar Irradiance
摘要： As the use of solar power as a source of electricity is increasing, so is the interest in modeling radiation at high temporal resolutions. High-dimensional remote sensing data products depend on cloud cover variability, atmosphere aerosol levels, and other atmospheric parameters. Because of weather fronts and aerosols, it is difficult to quantify solar power variability based on distributed solar networks. The global horizontal irradiance (GHI) component in the National Solar Radiation Database (NSRDB) is available at a 30-min time resolution. The algorithm proposed in this paper produces 1-min-resolution GHI samples at locations where NSRDB data are available. The synthetic irradiance datasets are produced using log-additive non-Gaussian mixture models and resampling techniques. The model is trained over historical data, and predicted values are compared with in situ data. This approach allows for estimating the solar irradiance at subhourly temporal resolutions, while featuring variability for locations where measurements are otherwise not available.
关键词： irradiance generation,stochastic modeling,mixture distribution,Downscaling
更新于2025-09-04 15:30:14
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Improving the calibration of silicon photodiode pyranometers
摘要： Reliable measurements of global irradiance are essential for research and practical applications. Silicon photodiode pyranometers (SiPs) offer low-cost sensors to measure direct and diffuse irradiance despite their non-uniform spectral response over the 300–1000 nm spectral range. In this study, non-adjusted linear and adjusted calibrations were applied at different times of the year to determine sources of estimated errors in global irradiance due to the two calibration approaches, calibration time, and sensor age. 16 SiPs, along with two standards, measured incident global irradiance over a 5-year period under a range of sky conditions. Sensors performed best in the months in which they were calibrated when using the linear calibration approach. With the solar zenith angle adjusted calibration approach, certain calibration months provide a defendable validation for the following 12 months [ranging an average of 13.5–17.4 W m?2 standard error (SE)], while other calibration months do not provide consistent results and sometimes result in very poor validation (31.1–242.7 W m?2 SE). Older sensors (greater than 6 years) in general become more sensitive to solar zenith angle and their response drifts over time, while newer SiPs performed better than older sensors. Calibrations which accounted for solar zenith angle effects improved global irradiance estimates for older SiPs. For the Lincoln NE location, the appropriate calibration is in spring or late summer, regardless of calibration approach. These results indicate that solar zenith angle correction is not needed for largely diffuse components under cloudy conditions, so that in the future, a “smart” calibration may be possible, where diffuse radiation fractions are known.
关键词： Silicon photodiode pyranometers,Sensor age,Calibration,Solar zenith angle,Global irradiance
更新于2025-09-04 15:30:14
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Revision of the Sun’s Spectral Irradiance as Measured by SORCE SIM
摘要： The Spectral Irradiance Monitor (SIM) instrument on board the Solar Radiation and Climate Experiment (SORCE) performs daily measurements of the solar spectral irradiance (SSI) from 200 to 2400 nm. Both temporal and spectral corrections for instrument degradation have been built on physical models based on comparison of two independent channels with different solar exposure. The present study derives a novel correction for SIM degradation using the total solar irradiance (TSI) measurements from the Total Irradiance Monitor (TIM) on SORCE. The correction is applied to SIM SSI data from September 2004 to October 2012 over the wavelength range from 205 nm to 2300 nm. The change in corrected, integrated SSI agrees within 0.1 W m?2 (1σ ) with SORCE TIM TSI and independently shows agreement with the SATIRE-S and NRLSSI2 solar models within measurement uncertainties.
关键词： Solar spectral irradiance,Degradation correction,Solar spectrum,Solar variability,Solar cycle
更新于2025-09-04 15:30:14