Mary Hudson

Mary Hudson Named Associate Fellow of the American Institute of Aeronautics and Astronautics

whawkins — Wed, 11 Jan 2023 15:44:57 +0000

Mary Hudson Named Associate Fellow of the American Institute of Aeronautics and Astronautics whawkins Wed, 01/11/2023 - 08:44

Gleissberg Cycle Dependence of Inner Zone Proton Flux

whawkins — Tue, 23 Aug 2022 16:21:36 +0000

Gleissberg Cycle Dependence of Inner Zone Proton Flux whawkins Tue, 08/23/2022 - 10:21

Author:

whawkins

Aug 23, 2022

Figure 1. 3-month averaged peak flux for >70 MeV protons in the SAA is normalized to flux (= 1) at the beginning of 2010 (top) and plotted against 10.7cm solar flux (F10.7, bottom) from 1980 to June, 2021 to extend Figure 3 in Qin et al. (JGR, 2014) which covered 1980 through 2009. Different colors are used to represent different POES satellites. Prior to the NOAA-15 data beginning in 1999, satellites measured >80 MeV proton flux. Qin et al. (JGR, g2014) found good agreement between the >80 MeV and >70 MeV proton flux data and determined that no correction factor was necessary. (F10.7 flux in s.f.u. = 10-22W m-2 Hz -1)

The inner zone proton radiation belt consisting of 10’s to >100 MeV protons trapped in the Earth’s magnetic field is examined from 1980 to mid-2021 using measurements from four NOAA POES satellites. A long-term increase in measured proton flux over four ~11 year cycles of solar activity is found. This increase correlates with the current one hundred year minimum in solar activity known as the Gleissberg cycle. Inner zone proton flux is correlated with decreasing solar irradiance maxima at a wavelength of 10.7 cm, serving as a proxy for Extreme Ultra Violet input to Earth’s atmosphere. It is found that current peak proton flux, occurring at a longitude and latitude where the Earth’s magnetic field is weaker, is at the highest levels seen since the begining of observations in 1980. A model calculation of the inner zone proton flux is found to generally confirm the long-term trend. We conclude that this trend observed over ~ 40 years accompanies an average decrease in solar EUV in comparison with previous solar maxima when EUV irradiation was higher as parametrized by F10.7. The reduced EUV at solar maximum reduces proton loss to the atmosphere, thus explaining the observed long-term increase in inner zone proton flux. Space Weather.

Statistical Dependence of EMIC Wave Scattering on Wave and Plasma Parameters

kolinski — Thu, 18 Nov 2021 17:08:21 +0000

Statistical Dependence of EMIC Wave Scattering on Wave and Plasma Parameters kolinski Thu, 11/18/2021 - 10:08

Publication Name: JGR Space Physics; First HAO Author's Name: Mary K. Hudson

Author:

kolinski

Nov 18, 2021

A recent statistical study has suggested that not all electromagnetic ion cyclotron (EMIC) waves can scatter relativistic electrons. However, knowledge of the factors that influence the EMIC wave scattering efficiency is still limited in observations. In our study, we perform 6 years of analysis of data from 2013 to 2018, with relativistic electron precipitation (REP) observed by POES and EMIC wave observations from Van Allen Probes. The coincidence occurrence rate between EMIC waves and relativistic electron precipitation events is about 34%. Proportion of different bands of EMIC wave events that are associated with REP is as follows: H+ band and He+ band waves occurring simultaneously >H+ band >He+ band occurrence, same as in our previous study (Qin et al., 2018, https://doi.org/10.1029/2018JA025419).

H+ band Electromagnetic Ion Cyclotron (EMIC) waves produce loss of relativistic electrons as seen by two Van Allen Probes spacecraft separated along orbit by ~ 1 hour during June 2015 storm (Qin et al., 2019). Statistical study of this type of event Qin et al., 2020.

It is also found that the coincidence occurrence rate of EMIC wave events and REP events increases with respect to increased background plasma density, with increases in the ratio of plasma frequency to local gyrofrequency, increasing EMIC wave power and when the wave frequency approaches the gyrofrequency. The dependence on background electron density is stronger than the dependence on the ratio of plasma frequency to gyrofrequency. The coincidence occurrence rate decreases as the magnetic field increases between 120 and 270 nT, consistent with a previous study. These results are critical for better understanding and predicting the REP into the upper atmosphere due to EMIC waves

Statistical Dependence of EMIC Wave Scattering on Wave and Plasma Parameters

kolinski — Tue, 16 Nov 2021 22:59:34 +0000

Statistical Dependence of EMIC Wave Scattering on Wave and Plasma Parameters kolinski Tue, 11/16/2021 - 15:59

Publication Name: JGR Space Physics; First HAO Author: Mary K. Hudson; Authors as listed in article: Murong Qin, Mary Hudson, Robyn Millan, Leslie Woodger, Xiaochen Shen

Author:

kolinski

Nov 16, 2021

A recent statistical study (Qin et al., 2018) has suggested that not all electromagnetic ion cyclotron (EMIC) waves can scatter relativistic electrons. However, knowledge of the factors that influence the EMIC wave scattering efficiency is still limited in observations. In our study, we perform 6 years of analysis of data from 2013 to 2018, with relativistic electron precipitation (REP) observed by POES and EMIC wave observations from Van Allen Probes. The coincidence occurrence rate between EMIC waves and relativistic electron precipitation events is about 34%. Proportion of different bands of EMIC wave events that are associated with REP is as follows: H+ band and He+ band waves occurring simultaneously >H+ band >He+ band occurrence, same as in our previous study (Qin et al., 2018, 10.1029/2018JA025419).

Mary Hudson

Mary Hudson Named Associate Fellow of the American Institute of Aeronautics and Astronautics

Recent News

Gleissberg Cycle Dependence of Inner Zone Proton Flux

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Statistical Dependence of EMIC Wave Scattering on Wave and Plasma Parameters

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Statistical Dependence of EMIC Wave Scattering on Wave and Plasma Parameters

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