Solar Spectral Irradiance Research Articles

Heating of the Magnetically Closed Corona and Physical Models of Solar and Stellar Spectral Irradiances

Heating of the Magnetically Closed Corona and Physical Models of Solar and Stellar Spectral Irradiances

The Next Decade of Solar Ultraviolet Spectral Irradiance — Continuity, Modeling, and Physics

The Next Decade of Solar Ultraviolet Spectral Irradiance — Continuity, Modeling, and Physics

Evaluation of the Solar Energy Nowcasting System (SENSE) during a 12-Months Intensive Measurement Campaign in Athens, Greece

Energy nowcasting is a valuable asset in managing energy loads and having real-time information on solar irradiation availability. In this study, we evaluate the spectrally integrated outputs of the SENSE system for solar irradiance nowcasting for the period of the ASPIRE (atmospheric parameters affecting spectral solar irradiance and solar energy) campaign (December 2020–December 2021) held in Athens, Greece. For the needs of the campaign, several ground-based instruments were operating, including two pyranometers, a pyrheliometer, a cloud camera, a CIMEL sunphotometer, and a precision spectral radiometer (PSR). Global horizontal irradiance (GHI) estimations were more accurate than direct normal irradiance (DNI). SENSE estimations are provided every 15 min, but when comparing bigger time intervals (hours-days), the statistics improved. A dedicated assessment of the SENSE’s inputs is performed in respect to ground-based retrievals, considering cloud conditions (from a sky imager), AOD, and precipitable water vapor from AERONET. The factor that established the larger errors was the visibility of the solar disc, which cannot be defined by the available sources of model inputs. Additionally, there were discrepancies between the satellite estimation of the clouds and the ground picture, which caused deviations in results. AOD differences affected more the DNI.

Choice of Solar Spectral Irradiance Model for Current and Future Remote Sensing Satellite Missions

The accuracy of surface reflectance estimation for satellite sensors using radiance-based calibrations can depend significantly on the choice of solar spectral irradiance (or solar spectrum) model used for atmospheric correction. Selecting an accurate solar spectrum model is also important for radiance-based sensor calibration and estimation of atmospheric parameters from irradiance observations. Previous research showed that Landsat 8 could be used to evaluate the quality of solar spectrum models. This paper applies the analysis using five previously evaluated and three more recent solar spectrum models using both Landsat 8 (OLI) and Landsat 9 (OLI2). The study was further extended down to 10 nm resolution and a wavelength range from Ultraviolet A (UVA) to shortwave infrared (SWIR) (370–2480 nm) using inversion of field irradiance measurements. The results using OLI and OLI2 as well as the inversion of irradiance measurements were that the more recent Chance and Kurucz (SA2010), Meftah (SOLAR-ISS) and Coddington (TSIS-1) models performed better than all of the previous models. The results were illustrated by simulating dark and bright surface reflectance signatures obtained by atmospheric correction with the different solar spectrum models. The results showed that if the SA2010 model is assumed to be the “true” solar irradiance, using the TSIS-1 or the SOLAR-ISS model will not significantly change the estimated ground reflectance. The other models differ (some to a large extent) in varying wavelength areas.

Multi-material described metasurface solar absorber design with absorption prediction using machine learning models

As an integral part of a STPV system, a solar absorber is essential to absorb most of the energy of the incident solar spectral irradiance. Metasurfaces have revolutionized contemporary research in optics and photonics and can benefit from the unique thermostable properties of refractory materials as well. We propose a metasurface-based solar absorber having a simple symmetric square-ring structure employing seven different refractory materials with an intent to boost the efficiency of the solar energy system. The proposed design exhibits broadband absorption for the visible regime and bears similarity to AM 1.5 solar spectral irradiance indicating the effectiveness of the design. The absorption is optimized in every case by varying the defining geometrical descriptors. The presented designs have in addition shown a high absorption rate over a range of incidence angles. Traditionally, the desired optical responses used to be obtained through electromagnetic simulation software by solving wave equation iteratively. This process spans hundreds of numerical calculations making it a time-consuming and computation-intensive strategy. Instead of following the classical numerical approaches for obtaining the EM responses, the data-driven intelligent approach based on machine learning is applied to predict the optical response. The algorithms including decision tree, K-nearest neighbor, linear and polynomial regression have been investigated for the due purpose of replacing the conventional simulations, with decision tree algorithm performing exceptionally fast and accurate. The trained models have shown an excellent predictability for broadband absorption (300–1200 nm), with MSE of the model equal to only 6.38 × 10−5 and R2 score of 0.9999. Further, we have trained the inverse model by employing a dimensionality reduction technique “PCA” on optical response vectors to predict the geometrical parameters of meta-atom yielding a min of 0.0 MSE and R2 score equal to 0.9999. The modeling procedure and numerical calculations are performed in a matter of seconds over the whole dataset especially when PCA with 10 components is applied. The presented approach bids a novel and effective methodology to speed up the on-demand design of intricate metasurfaces and optical structures for green energy applications.

Preface

Green energy refers to energy that can be directly used in production and life. It includes nuclear energy and renewable energy. With the continuous growth of energy demand and the increasing awareness of environmental protection in the countries around the world, it is urgent and imperative to establish a green energy innovation research and development, promotion and application system, and electricity will play a huge role in the development of green energy.2023 2nd International Conference on Green Energy and Power Systems (ICGEPS 2023) was held virtually under such a background in Changsha, China on January 6th to 8th, 2023. The aim of the symposium was to provide an opportunity for international experts, academics, researchers, practitioners and students working in the areas of green energy and power system to exchange information on the R&D and commercialization of green energy and power system. New developments, concepts, future research trends and potential commercialization areas were also discussed.The topics covered in the proceedings of ICGEPS 2023 are as follows: Power Systems and Its Automation, Measurement Technology and Instrumentation, Sensors and Micro Machines, Clean Energy Technology, Sustainable Coal Utilization and Clean Coal Technology, etc. Approximately 100 experts and scholars from almost 10 countries participated in the conference. The conference featured keynote speeches, oral presentations, and poster presentations.During the keynote speech part, three well-known professors delivered expertise lectures by imparting the latest findings from their respective research domains. Among them, Prof. Chong Kok Keong from Universiti Tunku Abdul Rahman, Malaysia addressed a keynote speech on Performance Analyses of Photovoltaic Module under Different Spectral Irradiances by Considering both Photonic and Electrical Characteristics. The solar spectral irradiance varies significantly for different locations and time due to latitude, humidity, cosine effect of incident sunlight, etc. To predict the actual performance of photovoltaic module under local climate conditions, he and his team proposed a methodology to compute the power-conversion efficiency of organic photovoltaic cells based upon indoor measurement with a solar simulator, the measured local solar spectrum, and making use of both optical and electrical factors. It was a wonderful opportunity for all the participants to interact with the experts and specialists to get their advice or suggestions.We would like to express our gratitude to all the participants for their presentations and discussions, which made the conference very successful indeed. We are also grateful to the Conference Chair, the Program Committee Chair, the Publication Chair, the Organizing Committee, and the Technical Program Committees for their fruitful work. We would like to express our thanks to all the authors for their time and genuine efforts, and to the reviewers for their fruitful comments during the preparation of this volume.The Committee of ICGEPS 2023List of Committee Member is available in this pdf.

Lower-ionosphere electron density and effective recombination coefficients from multi-instrument space observations and ground VLF measurements during solar flares

A new model to predict the electron density and effective recombination coefficient of the lower ionosphere under solar flare conditions is presented. This model relies on space-borne solar irradiance measurements in coincidence with ground recorded active transmissions of Very Low Frequency (VLF), (<30 kHz) signals. Use is made of the irradiance measured by broad-band radiometers onboard the satellites: GOES, SDO, and PROBA2. Measurements are made over succeeding and partly overlapping wavelength intervals of the instrument bandpass ranges altogether covering the range 0.1–20 nm. The aim is to determine the effectiveness of the particular instrument bandpass in producing changes in the ionization of the lower ionosphere (D-region) during solar X-ray flares. Ionization efficiency is evaluated using modelled Solar Spectral Irradiance for each flare separately and for each instrument as a function of its bandpass.The new model is based on coupling of the continuity equation with the Appleton relation and uses the concept of time delay – the time lag of the extreme VLF amplitude and phase behind the flare irradiance maximum. The solution of the continuity equation predicts the electron density time - height profile for 55–100 km altitude.An analysis of M to X class flares shows the flare-enhanced electron densities due to a particular ionizing wavelength domain are in good agreement for the case where irradiance is taken over the bandpass of (1) either GOES (0.1–0.8 nm) or SDO/ESP (0.1–7 nm) for up to 90 km (2) either SDO/ESP or PROBA2/LYRA (1–2 +6–20 nm) at heights above 90 km. The results agree within 22% for heights up to 90 km, and differ by at most a factor of 2 for heights above 90 km. Remarkable agreement is shown between measured and evaluated time delay; discrepancies are generally less than 8%. The effective recombination coefficient is deduced from the model itself and is found to be consistent with other independent estimates.

The photolytic conversion of 4-nonylphenol to 4-nonylcatechol within snowpack of the Palisade Glacier, Sierra Nevada, CA, USA

4-Nonylphenol (4-NP), an environmental pollutant with potent ecotoxicological effects, has been discovered in significant quantities in glacial ice and snow of the Sierra Nevada Mountain Range, CA. Photolysis of 4-NP is suspected to be a major, if not the sole, breakdown pathway in snow. However, the photolysis process has yet to be characterized in detail for this unique environment. This study therefore seeks to (1) confirm the presence of the major photolysis product within snowpack and snowmelt samples from the Palisade Glacier, CA, (2) determine key photolysis parameters through laboratory assays in snow analogs, and (3) compute environmentally relevant photolysis rates in snowpack via a spectral solar irradiance model parameterized for the Palisade Glacier. The primary photooxidation product of 4-NP, 4-nonylcatechol (4-NC), was synthesized and characterized by NMR and GC–MS for use as a reference standard in the detection of 4-NC in environmental samples. 4-NP was detected in all snowpack (n = 4) and snowmelt (n = 5) samples, with concentrations of 1.05 (± 0.11) μg L−1 and 1.28 (± 0.12) μg L−1, respectively. 4-NC was detected in all snowmelt outflow samples and all but one snow samples (88 % detection frequency) but was below the limit of quantification for the given method. All samples were collected during a sampling regime at the Palisade Glacier in August of 2021. Quantum yields of photolysis at the 277 nm absorption band were determined to be 0.36 (±0.06) and 0.21 (±0.06) in ultrapure water and liquid snow, respectively. Under clear sky conditions at the Palisade Glacier, half-lives for 4-NP are estimated to range from 235 to 251 h (9.8–10.5 days) based on assays conducted in liquid snowmelt and irradiance modeling. These results suggest that the photolysis of 4-NP, and hence the production of 4-NC, is occurring at significant rates within the snowpack where 4-NC is inevitably released to downstream catchment areas via snowmelt. 4-NC is significantly more toxic than its precursor, thereby raising amplified concerns for downstream human and wildlife populations. Furthermore, the ubiquity of 4-NP among the Earth's environments presents this as an issue of potentially global concern.

Version 2 of the TSIS‐1 Hybrid Solar Reference Spectrum and Extension to the Full Spectrum

AbstractThis work describes two achievements to a key data set. First, we present version 2 of the Total and Spectral Solar Irradiance Sensor‐1 Hybrid Solar Reference Spectrum (TSIS‐1 HSRS), which has recently been recognized as a new solar irradiance reference standard (https://calvalportal.ceos.org/). Second, we present a new “full spectrum extension” of the TSIS‐1 HSRS. The TSIS‐1 HSRS observational composite solar irradiance reference spectrum spans 0.202–2.730 μm and encompasses more than 97% of the energy in the total solar irradiance (TSI). Version 2 is an incremental update that corrects the radiometric baseline between 0.202 and 0.210 μm and updates the solar lines at wavelengths longward of 0.743 μm to those listed in the most recent database. The full spectrum extension builds off version 2 of the TSIS‐1 HSRS and supports applications that require a solar spectrum encompassing nearly 100% of the energy in the TSI. It spans 0.115–200 μm and was developed by incorporating additional observations and theoretical knowledge where no direct observations currently exist.

Comprehensive Modelling for Analyzing the Power Conversion Efficiency of Polycrystalline Silicon Photovoltaic Device under Indoor Operating Conditions

Recently, most of the studies were mainly focused on the variation between outdoor solar spectral irradiance and standard AM1.5G spectrum, as well as their effects towards the performances of different PV technologies. Interestingly, limited studies have been conducted to study the effect of artificial lighting on the power conversion efficiency of the photovoltaic (PV) device. The spectral irradiance produced by indoor lighting differs significantly as compared to the that of standard AM1.5G spectrum, which inevitably leads to different performances of the PV under standard test conditions and under artificial lighting exposure. In this study, the performance modelling has been carried out based on the comprehensive method proposed by Chong et al. to predict the PCE of organic solar cell devices. From the measurement results, the spectrum of LED illumination has been compared with that of AM1.5G, in which the LED shows a relatively narrow band with significant peaks at 450 and 560 nm. Furthermore, the theoretical model has been successfully validated by comparing the simulated PCE and the measured PCE at reasonably deviations in the range of 3.0 – 23.3%.

A model for the estimation of global spectral solar irradiance under all-sky conditions for Nakhon Pathom station, Thailand

In this work, a model was developed to estimate global spectral solar irradiance under all-sky conditions using data from the Nakhon Pathom station, Thailand. This model expresses the global spectral solar irradiance under all-sky conditions as the multiplication of two functions. The global spectral irradiance under clear sky conditions from the calculation and the cloud correction factor are considered in the model. The cloud correction factor is a function of the cloud index from Himawari satellite data and the ratio of global spectral irradiance under all sky conditions and clear sky conditions. The global spectral irradiance was measured at Nakhon Pathom station using a spectroradiometer (EKO, MS-710) from 2017 to 2019. Model validation was computed using the 2020 dataset. The global solar spectral irradiance from measurements and calculated from the model were found to be in reasonable agreement, with discrepancies in mean bias difference and root mean squared difference of 4.85% and 14.21%, respectively.

Overview of NASA’s Solar Irradiance Science Team #2 (SIST‐2) Program

AbstractThe Solar Irradiance Science Team (SIST) #2 (SIST‐2) program is a competitively solicited National Aeronautics and Space Administration (NASA) Earth Science Division science research program providing 3‐year awards beginning in July 2018 to quantify and understand the solar irradiance variability and implications for Earth's climate and atmospheric composition. The purpose for the SIST‐2 program is limited to the accurate specification of the incoming solar irradiance into the Earth system considering the 44‐year satellite data record as well as proxies to which the satellite record can be tied. The SIST‐2 program funded eight research grants to study the variability of the total solar irradiance and solar spectral irradiance and to develop improved space‐based data sets, solar proxies, and variability models of the solar irradiance. The SIST‐2 projects are briefly introduced.

Why Pacific quasi-decadal oscillation has emerged since the mid-20th century

Pacific quasi-decadal oscillation (PQDO) is one component of the multi-time-scale tropical Pacific decadal variability, with a variability center in the equatorial central Pacific (ECP). PQDO has emerged since the 1950s and has a significant impact on decadal climate variability over Asia and North America and Pacific storms. However, why it has intensified since the 1950s remains unknown. Here we test two competing hypotheses, (1) 11-year solar cycle forcing and (2) internal variability arising from El Niño–Southern Oscillation (ENSO) asymmetry, by analyzing simulation results, including one fixed-forcing control (CTRL) experiment and four sensitive experiments with millennial spectral solar irradiance (SSI), obtained from the Community Earth System Model–Last Millennium Ensemble modeling project. The four-member ensemble-averaged SSI experiments suggest that 11-year solar irradiance forcing cannot excite PQDO without stratospheric amplification of solar forcing. By analyzing 144 years of observations and the CTRL experiment, we find that the PQDO is nonstationary, and consecutive La Niña-induced decadal variability can boost PQDO in the ECP. El Niño could induce decadal ENSO signals in the NINO3.4 region but not in PQDO regions. The negative phase of PQDO tends to follow the occurrence of multi-year La Niña. We suggest that the emergence of PQDO since the 1950s is mainly due to the increase in multi-year La Niña events.

Performance optimization of a solar-driven alkali metal thermoelectric converter coupled to thermally regenerative electrochemical cycles

In order to improve the solar energy conversion efficiency, a novel coupling system comprised of a solar collector, an alkali metal thermoelectric converter (AMTEC), and thermally regenerative electrochemical cycles (TRECs) is constructed, in which the waste heat of AMTEC is used to drive TRECs to generate electricity. Taking into account the main irreversible losses, the analytical expressions for the efficiency and power output of the coupling system model are deduced. The optimum selection criteria of the system’s critical parameters are provided by introducing a multi-parameter combined objective function. Meanwhile, the efficiency and power output density are calculated under different given weight factors. Furthermore, the impacts of the surface temperature of the absorber, the current density in AMTEC, the electrolyte thickness, the regeneration efficiency of TRECs, and the incident spectral solar irradiance on the systemic performance at a given solar concentration ratio are evaluated in depth. Numerical calculation examples illustrate that with a solar concentration ratio of approximately 200, the maximum efficiency and maximum power output density of the coupling system are 28.57% and 49.51% higher than the solar-driven AMTEC system, respectively. Finally, the influences of the solar concentration ratio on the parametric optimum selection criteria are investigated. The present study may provide some new insights to enhance the efficiency of solar energy conversion.

Spectral Factor of Colored Solar Cells: A Case Study on the Main Urban Areas in Romania

PV modules for Building-Integrated Photovoltaic (BIPV) applications are made of different colors aimed at raising the visual aesthetic of the building. But a colored coating applied to the surface of a basic PV module is inherently associated to a decrease in conversion efficiency. From a different perspective, the efficiency of a PV module is evaluated under the industry standard test conditions (STC). Due to spectral mismatch, the efficiency of a PV module operating in outdoor conditions may substantially differ from the standard value evaluated at STC. In this study, the influence of spectral solar irradiance distribution on the colored PV module efficiency is evaluated in terms of spectral factor (SF). SF quantifies the relative power gain or loss caused by the spectral difference from STC. The theory is illustrated with a case study on the main four urban areas in Romania. The actual solar radiation spectrum is estimated with the simple Leckner spectral solar irradiance model, based on atmospheric parameters retrieved from the Aerosol Robotic Network (AERONET). The results emphasize that the aesthetic of BIPV comes at a high energy cost: depending on the color, a coating applied on the surface of a crystalline silicon PV module may reduce its conversion efficiency even by half.

Data-driven Model of Temporal Evolution of Solar Mg ii h and k Profiles over the Solar Cycle

The solar radiation in the cores of the Mg ii h and k spectral lines plays a significant role in the illumination of prominences, coronal mass ejections (CMEs), spicules, flare loops, and surges. Moreover, the radiation in these lines strongly correlates with solar magnetic activity and the ultraviolet solar spectral irradiance affecting the photochemistry, especially of oxygen and nitrogen, in the middle atmosphere of the Earth. This work provides a data-driven model of temporal evolution of the solar full-disk Mg ii h and k profiles over the solar cycle. The capability of the model to reproduce the Mg ii h and k profiles for an arbitrary date is statistically assessed. Based on selected 76 IRIS near-UV full-Sun mosaics covering almost the full solar cycle 24, we find the parameters of double-Gaussian fits of the disk-averaged Mg ii h and k profiles and a model of their temporal evolution parameterized by the Bremen composite Mg ii index. The model yields intensities within the uncertainties of the observed data in more than 90% of the reconstructed profiles assuming a statistically representative set of Bremen Mg ii index values in the range of 0.150–0.165. The relevant full-disk Mg ii h and k calibrated profiles with uncertainties and spectral irradiances are provided as an online machine-readable table. The model yields Mg ii h and k profiles representing the disk incident radiation for the radiative-transfer modeling of prominences, CMEs, spicules, flare loops, and surges observed at arbitrary time.

SI-traceable solar irradiance measurements for aerosol optical depth retrieval

The overall aim of this study is to enable the traceable to International System of Units (SI) determination of column-integrated aerosol optical depth (AOD) retrieved from the passive remote sensing of the atmosphere using SI-traceable direct solar spectral irradiance measurements. A precision filter radiometer that measures direct solar spectral irradiance for the retrieval of AOD has been characterized and calibrated at the state-of-the-art calibration facilities of Physikalisch-Technische Bundesanstalt. The measured SI-traceable solar irradiances together with three state-of-the-art top-of-the-atmosphere (TOA) solar spectra have been used for retrieving AODs, which were validated against the reference AOD instruments of the World Aerosol Optical Depth Calibration Centre of the World Meteorological Organization (WMO). Calibration factors agreed within ±0.57% (3σ) using all three TOA spectra except for 368 nm (−1.1%) and 862 nm (1.8%) channels for one out of the three TOA spectra. Application of these results to the AOD retrieval showed AOD differences with the current reference methods/instruments well within the recommended WMO limits. The work provides a first step to opening a new era of AOD measurements traceability, providing a link to the SI through a laboratory-based approach, with the main advantages being the low uncertainty, the possibility of enhancing global AOD homogenization efforts and the chance to avoid calibration activities based on instrument relocations.

Long-Term Trend Analysis in the Solar Radiation and Climate Experiment (SORCE)/Spectral Irradiance Monitor (SIM)

The Solar Radiation and Climate Experiment/Spectral Irradiance Monitor (SORCE/SIM) instrument was launched on 25 January 2003 with mission termination occurring on 25 February 2020. The SORCE/SIM provides a unique data set of the variability in solar spectral irradiance (SSI) during the descending phase of Solar Cycle 23 (SC23) from April 2003 to February 2009, the weaker solar-maximum conditions of SC24, and the quiescent SC24/SC25 minimum. The determination of the magnitude and phase of SSI variations rely on the unambiguous determination of the effects of the space environment and solar-exposure-related degradation mechanisms. The instrument-only corrections for SIM are based on a comparison of two functionally identical (mirror image) prism spectrometers with four independent detectors in each spectrometer channel. The degradation correction is strictly instrumental in its methodology and makes no assumptions about the magnitude, slope, or wavelength dependence of the SSI variability.

Estimates of Hyperspectral Surface and Underwater UV Planar and Scalar Irradiances from OMI Measurements and Radiative Transfer Computations

Quantitative assessment of the UV effects on aquatic ecosystems requires an estimate of the in-water hyperspectral radiation field. Solar UV radiation in ocean waters is estimated on a global scale by combining extraterrestrial solar irradiance from the Total and Spectral Solar Irradiance Sensor (TSIS-1), satellite estimates of cloud/surface reflectivity, ozone from the Ozone Monitoring Instrument (OMI) and in-water chlorophyll concentration from the Moderate Resolution Imaging Spectroradiometer (MODIS) with radiative transfer computations in the ocean-atmosphere system. A comparison of the estimates of collocated OMI-derived surface irradiance with Marine Optical Buoy (MOBY) measurements shows a good agreement within 5% for different seasons. To estimate scalar irradiance at the ocean surface and in water, we propose scaling the planar irradiance, calculated from satellite observation, on the basis of Hydrolight computations. Hydrolight calculations show that the diffuse attenuation coefficients of scalar and planar irradiance with depth are quite close to each other. That is why the differences between the planar penetration and scalar penetration depths are small and do not exceed a couple of meters. A dominant factor defining the UV penetration depths is chlorophyll concentration. There are other constituents in water that absorb in addition to chlorophyll; the absorption from these constituents can be related to that of chlorophyll in Case I waters using an inherent optical properties (IOP) model. Other input parameters are less significant. The DNA damage penetration depths vary from a few meters in areas of productive waters to about 30–35 m in the clearest waters. A machine learning approach (an artificial neural network, NN) was developed based on the full physical algorithm for computational efficiency. The NN shows a very good performance in predicting the penetration depths (within 2%).

Solar Radiation and Climate Experiment (SORCE) X-Ray Photometer System (XPS): Final Data-Processing Algorithms

The X-ray Photometer System (XPS) is one of four instruments onboard NASA’s Solar Radiation and Climate Experiment (SORCE) mission. The SORCE spacecraft operated from 2003 to 2020 to provide key climate-monitoring measurements of total solar irradiance (TSI) and solar spectral irradiance (SSI). The XPS is a set of photometers to measure the solar X-ray ultraviolet (XUV) irradiance shortward of 34 nm and the bright hydrogen emission at 121.6 nm. Each photometer has a spectral bandpass of about 7 nm, and the XPS measurements have an accuracy of about 20%. The updates for the final data-processing algorithms for the XPS solar-irradiance data products are described. These processing updates include improvements for the instrumental corrections for background signal, visible-light signal, and degradation trending. Validation of these updates is primarily with measurements from a very similar XPS instrument onboard NASA’s Thermosphere-Ionosphere-Mesosphere-Energetics-Dynamics (TIMED) mission. In addition, the XPS Level 4 spectral model has been improved with new reference spectra derived with recent XUV observations from NASA’s Solar Dynamics Observatory (SDO) and Miniature X-ray Solar Spectrometer (MinXSS) cubesat.