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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 253 records · Page 14

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NASA NTRS1997

The solar minimum X2.6/1B flare and CME of 9 July 1996: Propagation - Pt 2

The interplanetary propagation aspects of the first X-class solar flare and coronal mass ejection are discussed. The solar data relevant to this event are summarized. Data from WIND and charge element and isotope analysis system (CELIAS) show solar wind plasma and interplanetary magnetic field disturbances early on 12 July 1996. It was observed that the extrapolation of the coronal mass ejection back to the flare time suggests a close association between them. Moreover, the coronal mass ejection speed is similar to the type two shock's speed. The results suggest that the coronal mass ejection is intimately related to the shock itself.

Dryer, M.↗

NASA NTRS1971

MIT solar wind plasma data from Explorer 33 and Explorer 35: July 1966 to September 1970

The plasma experiments on Explorer 33 and Explorer 35 have yielded large amounts of solar wind data. This report gives a brief review of the method used to obtain the data, provides a description of the plasma parameters, and describes in detail the format of the plots and tapes which are available from the Data Center. Hourly average plots of the data are included at the end of the report. From these plots, the availability and interest of the solar wind data for any period of time may be determined.

Howe, H.↗

DOE OSTI2022

Incorporating polar field data for improved solar flare prediction

In this paper, we consider incorporating data associated with the sun’s north and south polar field strengths to improve solar flare prediction performance using machine learning models. When used to supplement local data from active regions on the photospheric magnetic field of the sun, the polar field data provides global information to the predictor. While such global features have been previously proposed for predicting the next solar cycle’s intensity, in this paper we propose using them to help classify individual solar flares. We conduct experiments using HMI data employing four different machine learning algorithms that can exploit polar field information. Additionally, we propose a novel probabilistic mixture of experts model that can simply and effectively incorporate polar field data and provide on-par prediction performance with state-of-the-art solar flare prediction algorithms such as the Recurrent Neural Network (RNN). Our experimental results indicate the usefulness of the polar field data for solar flare prediction, which can improve Heidke Skill Score (HSS2) by as much as 10.1%.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRSDate not supplied

A Machine Learning Ready Dataset of Acoustic Power Maps for Detection of Active Region Emergence

The development of an accurate forecast for solar eruptive activity has become increasingly important in order to prevent any potential impact on activities in space and the Earth's environment. It is therefore crucial to detect active regions before they appear on the solar surface and create early warning capabilities for upcoming Space Weather disturbances. In this work, 9TB of solar data (SDO/HMI dopplergrams, magnetograms and continuum intensity maps) involving the emergence of 61 NOAA solar active regions since 2010 were processed using the NASA HECC capabilities. An acoustic power maps time-series dataset was created (for four different frequency ranges and processed to take into account the solar sphere geometric effect ) which can be used for understanding the dynamics of the solar surface and train a variety of ML models. The calculated acoustic power maps carry precursor information associated with the decrease in continuum intensity on the solar surface, verifying older helioseismology research. Our results show that a Long Short-Term Memory (LSTMs) model, with a modest layer depth and the right hyperparameters tuned, when trained on this solar acoustic power maps dataset can predict without false negatives a drop in intensity (associated with the emergence of the active region), up to 18 hours in advance.

SMD↗

NASA NTRS2022

Extreme Energetic Particle Events By Superflare-Associated CMES From Solar-Like Stars

Discovery of frequent superflares on active cool stars opened a new avenue in understanding the properties of eruptive events and their impact on exoplanetary environments. Solar data suggest that coronal mass ejections (CMEs) should be associated with superflares on active solar-like planet hosts and produce solar/stellar energetic particle (SEP/StEP) events. Here, we apply the 2D Particle Acceleration and Transport in the Heliosphere model to simulate the SEPs accelerated via CME-driven shocks from the Sun and young solar-like stars. We derive the scaling of SEP fluence and hardness of energy spectra with CME speed and associated flare energy. These results have crucial implications for the prebiotic chemistry and expected atmospheric biosignatures from young rocky exoplanets as well as the chemistry and isotopic composition of circumstellar disks around infant solar-like stars.

Junxiang Hu↗

NASA NTRS1985

The handling of data in solar-terrestrial and in planetary physics

The evolution of data handling systems for solar-terrestrial and planetary physics applications is discussed. The main elements of data management systems for scientific satellites are described, including: command and control; data transmission; prioritization of data users; and data reduction and analysis. The design approaches incorporated into the data management systems of the Interplanetary Monitoring Platform (IMP), International Sun Earth Explorer (ISEE), and the Orbiting Geophysical Observatory, (OGO) spacecraft, are discussed. Emphasis is given to classical, centralized, and hybrid system designs. The report of the Committee on Data Management and Computation (CODMAC) concerning concepts for new data management systems is briefly summarized.

Vette, J. I.↗

DOE OSTI2022

ARPA-E PERFORM datasets

Time-coincident load, wind, and solar data including actual and probabilistic forecast datasets at 5-min resolution for ERCOT, MISO, NYISO, and SPP. Wind and solar profiles are supplied for existing sites as well as planned sites based on interconnection queue projects as of 2021. For ERCOT actuals are provided for 2017 and 2018 and forecasts for 2018, and for the remaining ISOs actuals are provided for 2018 and 2019 and forecasts for 2019. There datasets were produced by NREL as part of the ARPA-E PERFORM project, an ARPA-E funded program that aim to use time-coincident power and load seeks to develop innovative management systems that represent the relative delivery risk of each asset and balance the collective risk of all assets across the grid. For more information on the datasets and methods used to generate them see https://github.com/PERFORM-Forecasts/documentation.

5-min data↗

NASA NTRS2011

Understanding Space Weather: The Sun as a Variable Star

The Sun is a complex system of systems and until recently, less than half of its surface was observable at any given time and then only from afar. New observational techniques and modeling capabilities are giving us a fresh perspective of the solar interior and how our Sun works as a variable star. This revolution in solar observations and modeling provides us with the exciting prospect of being able to use a vastly increased stream of solar data taken simultaneously from several different vantage points to produce more reliable and prompt space weather forecasts. Solar variations that cause identifiable space weather effects do not happen only on solar-cycle timescales from decades to centuries; there are also many shorter-term events that have their own unique space weather effects and a different set of challenges to understand and predict, such as flares, coronal mass ejections, and solar wind variations

Strong, Keith↗

NASA NTRS2012

Understanding Space Weather: The Sun as a Variable Star

Sun: Corona↗

NASA NTRS1995

An empirical determination of the polytropic index for the free-streaming solar wind using Helios 1 data

Observations of solar wind proton temperatures indicate that the solar wind is heated as it moves outward toward the orbit of Earth. This heating, which may be the results of electron heat conduction and perhaps MHD waves, has proven difficult to quantify and hence is often neglected in MHD models of the solar wind. An alternate approach to finding explicit heating terms for the MHD energy equation is to use a polytropic approximation. This paper discusses the properties of the polytropic approximation and its application to the solar wind plasma. By using data from the Helios 1 spacecraft, an empirical value for the polytropic index of the free-streaming solar wind is determined. Various corrections to the data are made to account for velocity, nonuniformity in radial sampling, and stream interaction regions. The polytropic index, as derived from proton data, is found to indepedent of speed state, within statistical error, and has an average value of 1.46. If magnetic pressure is included, the polytropic index has an average value of 1.58.

Totten, T. L.↗

NASA NTRS1977

The presence of Si I series in the ultraviolet solar spectrum - 3000 to 1200 A

Laboratory and solar data are presented which form the basis for identifying chromospheric Si I absorption lines in UV rocket spectra of the solar limb. Prints of the Si I laboratory spectrum between 1520 and 1570 A are matched with those of the chromospheric spectrum, and a striking line-to-line coincidence is observed. Individual absorption series of Si I covering the 3p(2), 3P, 1D, and 1S ground terms are tabulated in multiplet form over the wavelength range from 1517 to 3069 A. It is noted that many of the solar lines are blended with both other Si I lines and lines of other spectra.

Moore, C. E.↗

NASA NTRS1987

Statistical analysis of total ozone and stratospheric Umkehr data for trends and solar cycle relationship

Dobson total ozone data from 1970-1984 and stratospheric Umkehr profile ozone data from 1970-1981 are analyzed. The relationship between ozone and long-term solar cycle activity is examined using 10.7 cm solar flux data. From the Dobson data it is estimated that the overall global trend in total ozone is -0.26 + or -0.92 percent per decade, which indicates no significant overall trend; and for the total ozone-solar flux relationship there is a 1.18 + or - 0.66 percent change in total ozone from solar cycle minimum to maximum that reveals a positive relationship. Analysis of the Umkehr data reveals a negative trend of -0.30 + or - 0.17 percent per year in the layers 7 snd 8. The relationship between Umkehr data and solar flux in layers 6 and 7 is 2.57 + or - 1.25 percent and 3.40 + or - 2.16 percent change from solar cycle minimum to maximum; however, no significant relationship is detected in the higher layers 8 and 9. These estimates are compared with theoretical model calculations. It is noted that the estimated effects of solar cycle activity on total ozone and stratospheric ozone agree with calculations of photochemical models.

Reinsel, Gregory C.↗

NASA NTRS1982

Evidence for delayed second phase acceleration in solar flares

Data gathered on solar gamma-ray events by the gamma-ray spectrometer on board the HEAO-3 satellite are discussed. Measurements were made of both hard X-ray and gamma-ray events. A total of 37 flare-like incidences were detected from October 1979 to July 1980. Power law spectra were fitted to the flux energies exceeding 420 keV. The appearance of two events with a 30 sec interval between radiation peaks, a slow rise and quick decay of the high energy component, and the softening of the low energy component are taken for evidence of two acceleration processes, one boosting electrons to hundreds of keV for the X ray bursts, the other producing gamma rays through ions accelerated to tens of MeV.

Willett, J. B.↗

NASA NTRS1985

The status of the Nimbus-7 earth-radiation-budget data set

Over six years of data from the earth-radiation-budget (ERB) experiment on board the Nimbus-7 spacecraft have been received to date. Five years of data have been archived and are readily available to the scientific community, while the sixth year's data will be archived by the fall of 1985. There are three complementary, but independent, data sets: earth-radiation-budget data, solar-irradiance data, and shortwave- and longwave-radiance data suitable for bidirectional-reflectance studies. The solar and the wide-field-of-view earth-flux channels are still recording high-quality data, but the narrow-field-of-view scanner failed after 20 months. The condition of the three data sets is described. In addition, plans for data-set improvement are discussed and a simple algorithm to improve the wide-field-of-view data is presented.

Kyle, H. L.↗

NASA NTRS1998

Solar Irradiance and Thermospheric Airglow Rocket Experiments

This report describes work done in support of the Solar Irradiance and Thermospheric Air-glow Rocket Experiments at the University of Colorado for NASA grant NAG5-5021 under the direction of Dr. Stanley C. Solomon. (The overall rocket program is directed by Dr. Thomas N. Woods, formerly at the National Center for Atmospheric Research, and now also at the University of Colorado, for NASA grant NAG5-5141.) Grant NAG5-5021 provided assistance to the overall program through analysis of airglow and solar data, support of two graduate students, laboratory technical services, and field support. The general goals of the rocket program were to measure the solar extreme ultraviolet spectral irradiance, measure the terrestrial far-ultraviolet airglow, and analyze their relationship at various levels of solar activity, including near solar minimum. These have been met, as shown below. In addition, we have used the attenuation of solar radiation as the rocket descends through the thermosphere to measure density changes. This work demonstrates the maturity of the observational and modeling methods connecting energetic solar photon fluxes and airglow emissions through the processes of photoionization and photoelectron production and loss. Without a simultaneous photoelectron measurement, some aspects of this relationship remain obscure, and there are still questions pertaining to cascade contributions to molecular and atomic airglow emissions. However, by removing the solar irradiance as an "adjustable parameter" in the analysis, significant progress has been made toward understanding the relationship of far-ultraviolet airglow emissions to the solar and atmospheric conditions that control them.

Solomon, Stanley C.↗

DOE OSTI2023

Developing the Proof of Concept for the SERI QC Flag Translation

SERI QC is a robust solar data quality assessment software tool that has been in continuous use for more than three decades. This report, the second of six in the Data Quality and Uncertainty Integration project, develops the proof of concept, including programming in C and a collection of spreadsheet tools, for estimating the operational uncertainty from three-component solar irradiance measurements using information available from SERI QC. The report establishes a field reference for determining the operational uncertainty for each irradiance component based on the SERI QC coupling. Results demonstrate that the operational uncertainty estimates based on global irradiance best represent the collective results for all sky conditions.

14 SOLAR ENERGY↗

DOE OSTI2021

Behind the Meter Solar+Storage: Market data and trends [Slides]

As the distributed solar market evolves toward more dynamic forms of deployment, interest in paired solar-plus-storage applications continues to gain steam, but details on the current state of the market are relatively sparse. To fill that void, Berkeley Lab has released an in-depth analysis of this budding market segment. This report draws on the Lab’s Tracking the Sun dataset to characterize trends in deployment, system sizing and equipment selection, installer-market development, and system pricing. The report also provides indicative analyses of the financial and resilience value that host customers in several key markets presently receive by pairing storage with solar.

14 SOLAR ENERGY↗

DOE OSTI2022

Fort Mojave Indian Tribe Aha Macav Power Service Renewable Energy Project

Aha Macav Power Service (AMPS), on behalf of the Fort Mojave Indian Tribe received a Department of Energy Solar grant. Partnering with Stockbridge Energy Group and the Department of Energy, AMPS was able to construct, install, test and successfully put into operation a 2.3 MW solar field. As provided in the solar data, this project has helped to offset the cost of open market purchase power needed to meet the needs of the Tribe. The estimated value of the solar energy produced in FY2021 currently is more than $294,000. Eventual expansion of the solar project is projected to create future energy independence for the Fort Mojave Indian Tribe.

14 SOLAR ENERGY↗