Browsing by Author "Stoneback, Russell"
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Item Providing Wavelength Resolved Irradiance Measurements by Using Machine Learning(2021-12-01T06:00:00.000Z) Zhang, Yichao; Biewer, Michael C.; Lary, David J.; Stoneback, Russell; Lou, Xinchou; Anderson, Phillip C.; Da Silveira Rodrigues, FabianoSunlight incident on the Earth’s atmosphere is essential for life and is the driving force for atmospheric photo-chemistry. Atmospheric photo-chemistry is central to understanding urban air quality and the host of associated human health impacts. In this dissertation, two solutions were proposed to address the current lack of real-time wavelength-resolved solar irradiance data across cities. Our first solution is based on the machine learning calibration of low-cost light sensors. These calibrated sensors have a strong performance and can be readily deployed at scale across dense urban environments to measure the wavelength resolved irradiance on a neighborhood scale. This work has been published in MDPI (Zhang et al., 2021). Our second solution is based on the comprehensive dataset from public environmental sensors. We developed another machine learning model to estimate the wavelength resolved solar irradiance from solar zenith angle, earth distance, and multiple environmental dataset, such as relative humidity, total column ozone, earth surface reflectance, and radar reflectivities in the sky. All these factors can be accessed from the public datasets of weather stations and remote sensing systems. Using this solution, wavelength resolved solar irradiance can be estimated in a neighborhood scale, without implementing any additional sensors.Item Solar Influences on the Return Direction of High-Frequency Radar Backscatter(Blackwell Publishing Ltd) Burrell, Angeline G.; Perry, G. W.; Yeoman, T. K.; Milan, S. E.; Stoneback, Russell; 0000-0001-8875-9326 (Burrell, AG); 0000-0001-7216-4336 (Stoneback, R); Burrell, Angeline G.; Stoneback, RussellCoherent-scatter, high-frequency, phased-array radars create narrow beams through the use of constructive and destructive interference patterns. This formation method leads to the creation of a secondary beam, or lobe, that is sent out behind the radar. This study investigates the relative importance of the beams in front of and behind the high-frequency radar located in Hankasalmi, Finland, using observations taken over a solar cycle, as well as coincident observations from Hankasalmi and the Enhanced Polar Outflow Probe Radio Receiver Instrument. These observations show that the relative strength of the front and rear beams is frequency dependent, with the relative amount of power sent to the front lobe increasing with increasing frequency. At the range of frequencies used by Hankasalmi, both front and rear beams are always present, though the main beam is always stronger than the rear lobe. Because signals are always transmitted to the front and rear of the radar, it is always possible to receive backscatter from both return directions. Examining the return direction as a function of local time, season, and solar cycle shows that the dominant return direction depends primarily on the local ionospheric structure. Diurnal changes in plasma density typically cause an increase in the amount of groundscatter returning from the rear lobe at night, though the strength of this variation has a seasonal dependence. Solar cycle variations are also seen in the groundscatter return direction, modifying the existing local time and seasonal variations. ©2018 American Geophysical Union. All Rights Reserved.