Abstract:
These data include pitch angle diffusion coefficients for chorus waves which have been evaluated at the angle of loss cone calculated in multiple ways. We have predominately concentrated on the dawnside between 00-12 MLT (Magnetic Local Time), for 5<L*<5.5 as this is where we have Van Allen Radiation Belt Storm Probes (RBSP) measurements and scattering of electrons due to chorus waves is known to occur. We have used 7 years of RBSP wave and cold plasma measurements between November 2012 to October 2019 to calculate these diffusion coefficients. For the first two sets of data we provide chorus diffusion coefficients with fpe/fce times by 2 and divided by 2 respectively. The next four data sets have been calculated from RBSP data using two different methods, first using average values, as has previously been done (e.g. Horne et al [2013]) and used above, and secondly by using co-located measurements of the wave spectra and fpe/fce to calculate pitch angle diffusion coefficients (Daa), where fpe is the plasma frequency and fce is the proton gyro frequency, and then averaging, similar to that presented in Ross et al [2021] for Electromagnetic Ion Cyclotron (EMIC) waves and Wong et al [2022] for magnetosonic waves. Both methods use a modified version of the PADIE code Glauert et al [2005] which allows an arbitrary wave power spectral density input rather than Gaussian inputs. The RBSP chorus diffusion coefficient matrices are computed by combining RBSP data with a profile for how chorus wave power changes with latitude, derived from the VLF database in Meredith et al [2018]. The magnetic latitude profile enables us to map RBSP measurements to magnetic latitudes between 0<MLAT<60 and therefore include the effects of high latitude chorus in our results. The RBSP diffusion matrices also use a new chorus wave normal angle model derived from RBSP data composed of different wave normal angle distributions for different spatial location and fpe/fce bins. Lastly we include two data sets of RBSP-chorus diffusion coefficients combined with diffusion coefficients due to collisions with atmospheric particles to calculate the total diffusion of electrons near the loss cone between 00-12 MLT, for 5<L*<5.5. We have produced these different sets of chorus (and combined chorus and collision) diffusion coefficients to test our methods of calculating electron precipitation and find what variables these calculations are sensitive to.
Funding was provided by NERC Highlight Topic Grant NE/P01738X/1 (Rad-Sat) and NERC National Capability grants NE/R016038/1 and NE/R016445/1
Keywords:
electron precipitation, pitch angle diffusion coefficients, radiation belt model, wave-particle interactions
Reidy, J., Ross, J., & Wong, J. (2023). Pitch angle diffusion coefficients used in comparison of quasi-linear diffusion theory with in-situ measurements (Version 1.0) [Data set]. NERC EDS UK Polar Data Centre. https://doi.org/10.5285/5ef0d6cd-67c2-48fc-8a6a-dfe44a63979e
| Use Constraints: | Data released under the Open Government Licence V3.0 : http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/ |
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| Creation Date: | 2023-07-13 |
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| Dataset Progress: | Complete |
| Dataset Language: | English |
| ISO Topic Categories: |
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| Parameters: |
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| Personnel: | |
| Name | UK Polar Data Centre |
| Role(s) | Metadata Author |
| Organisation | British Antarctic Survey |
| Name | Jade Reidy |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Name | Johnathan Ross |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Name | Jin-Mann Wong |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Name | Dr Nigel Meredith |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Name | Dr Sarah Glauert |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Parent Dataset: | N/A |
| Reference: | Abel, B., & Thorne, R. M. (1998). Electron scattering loss in earth's inner magnetosphere: 1. dominant physical processes. Journal of Geophysical Research: Space Physics, 103(A2), 2385- 2396. doi: https://doi.org/10.1029/97JA02919 Glauert, S. A., & Horne, R. B. (2005). Calculation of pitch angle and energy diffusion coefficients with the PADIE code. Journal of Geophysical Research (Space Physics), 110(A4), A04206. doi: https://doi.org/10.1029/2004JA010851 Meredith, N. P., Horne, R. B., Shen X. C., Li, W., and Bortnik, J. (2020) Global Model of Whistler Mode Chorus in the Near-Equatorial Region628 ( < 18◦). Geophysical Research Letters, https://doi.org/10.1029/2020GL087311 Reidy, J. A., Horne, R.B., Glauert, S. A., Clilverd, M. A., Meredith, N. P., Woodfield, E. E., Ross, J. P., Allison, H. J. and Rodger, C. J. (2021) Comparing electron precipitation fluxes calculated from pitch angle diffusion coefficients to satellite observations, Journal of Geophysical Research: Space Physics, 126 (3), e2020JA028410. Doi: https://doi.org/10.1029/2020JA028410 Reidy, J. A., Horne, R.B., Glauert, S. A., Clilverd, M. A., Meredith, N. P., Rodger, C. J. Ross, J. P., and Wong, J. (2023) Characterising radiation-belt energetic electron precipitation spectra: a comparison of quasi-linear diffusion theory with in-situ measurements, Submitted to Journal of Geophysical Research Ross, J. P. J., Glauert, S. A., Horne, R. B., Watt, C. E., Meredith, N. P., & Woodfield, E. E. (2020). A New Approach to Constructing Models of Electron Diffusion by EMIC Waves in the Radiation Belts. Geophysical Res. Lett., 47 (20), e88976. doi: https://doi.org/10.1029/2020GL088976 Wong, J.-M., Meredith, N. P., Horne, R. B., Glauert, S. A., & Ross, J. P. J. (2022). Electron Diffusion by Magnetosonic Waves in the Earth's Radiation Belts. Journal of Geophysical Research (Space Physics), 127 (4), e30196. doi: https://doi.org/10.1029/2021JA030196 |
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| Quality: | Any places where there are no data are set to NaNs. | |
| Lineage: | The chorus diffusion coeffcients for (a) and (b) were derived using combined observations from seven spacecraft; these observations are binned by L*, MLT, magnetic latitude and geomagnetic activity level as described in Meredith et al. (2020) but calculated with either fpe/fce divided or times by 2. The chorus diffusion coefficients for (c) and (d) were calculated using solely RBSP wave measurements, as opposed to the entire wave data base with data from seven different satellites discussed above. The old and new method refers to the whether the wave data were combined before or after the average was taken, as described in Ross et al (2020) and Wong et al (2022). All four chorus matrix files were calculated using the PADIE code (Glauert & Horne, 2005). For files (e) - (h) - the above chorus diffusion coefficients from (a)- (d) were combined with diffusion coefficients for coulomb collisions (calculated as outlined in Abel and Thorne (1998)). |
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| Temporal Coverage: | |
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| Start Date | 2012-11-01 |
| End Date | 2019-10-31 |
| Location: | |
| Location | N/A |
| Detailed Location | Van Allen Radiation Belts |
| Data Collection: | These diffusion coefficients were initially calculated using the PADIE code (Glauert & Horne, 2005). |
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| Distribution: | |
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| Distribution Media | Online Internet (HTTP) |
| Distribution Size | 100 kB |
| Distribution Format | N/A |
| Fees | N/A |
| Data Storage: | This file contains eight NetCDF files: a) chorus_fpefce_times2.nc b) chorus_fpefce_div2.nc c) chorus_RBSP_old.nc d) chorus_RBSP_new.nc e) combined_fpefce_time2.nc f) combined_fpefce_div2.nc g) combined_RBSP_old.nc h) combined_RBSP_new.nc Each file contains a matrix with the diffusion coefficients, labelled daa, and arrays detailing the matrix size. They are all structured as follows (they have all been evaluated at L* = 5.25 and loss cone pitch angle of 3.59 degrees, assuming a dipole.): Daa [n_energy, n_mlt, n_act], where n_energy, n_mlt and n_act are given as separate arrays. a) and b) contain bounce averaged chorus diffusion coefficients presented in Figure 7 of Reidy et al (2023) between 5 < L* < 5.5, 06 < MLT < 12, 10 - 1000 keV and separated into activity bins of low (0< Kp < 1), moderate (2 < Kp < 3) and high (4 < Kp < 7) at the loss cone. The arrays containing the energy, MLT and Kp dependence are also included. c) and d) contain bounce averaged chorus diffusion coefficients presented in Figures 9 and 10 of Reidy et al (2023) between 5 < L* < 5.5, 00 < MLT < 12, 10 - 1000 keV and separated into activity bins of low (0< Kp < 1), moderate (2 < Kp < 3) and high (4 < Kp < 7) at the loss cone. The arrays containing the energy, MLT and Kp dependence are also included. e) and f) contain the combined chorus and collision diffusion coefficients used to calculate the precipitation presented in Figure 8 of Reidy et al (2023) between 5 < L* < 5.5, 09 < MLT < 12, energy between 10kev - 1MeV at the loss cone for five geomagnetic activity levels (0< Kp < 1, 1< Kp < 2, 2 < Kp < 3, 3 < Kp < 4, 4 < Kp < 7). The arrays containing the energy, MLT and Kp dependence are also included. g) and h) contain the combined chorus and collision diffusion coefficients used to calculate the precipitation presented in Figures 11 and 12 of Reidy et al (2023) between 5 < L* < 5.5, 00 < MLT < 12, energy = 10keV - 5 MeV at the loss cone for five geomagnetic activity levels (0< Kp < 1, 1< Kp < 2, 2 < Kp < 3, 3 < Kp < 4, 4 < Kp < 7). |