5:15 PM - 6:45 PM
[PEM15-P08] Evaluation of an optical method using photometer data to derive the electron density
Keywords:photometer, E region, auroral, EISCAT, Tromso
A suitable multi-wavelength observation of auroral emissions allows us to deduce the energy distribution of auroral particles (Robinson and Vondrak 1994). Adachi et al. (2017) evaluated a photometric method (Ono 1993) of derivation of ionospheric conductivities based on simultaneous observations of a photometer (field of view (FOV)= about 1.2 degrees), a digital camera, and the EISCAT UHF radar (FOV = about 0.7 degrees) operated at Tromsoe, Norway (69.6 deg N, 19.2 deg E), for two nights on October 10 and 11, 2002. They compared height-integrated Pedersen and Hall conductivities with 10 second resolution obtained from EISCAT UHF radar (a field-aligned mode; CP-1 mode) observations and photometer observations with wavelengths of 427.8 and 630.0 nm. Sky images taken with a digital camera were used for distinguishing aurora classes in the views of the EISCAT radar and the photometer. A good agreement of temporal variations of the height-integrated Pedersen and Hall conductivities was found between EISCAT radar and photometer values. In cases of auroral arcs passing by in the views, however, differences in derived values between the two instruments were found. They concluded that (1) the photometric method using 427.8 and 630 nm was able to capture temporal variations of the conductivities well, but unavoidable underestimations of the Pedersen (about 30–40%) and the Hall (about 50–60%) conductivities were involved, and (2) care was necessary for using photometric observational data when auroral arcs appear in the view.
To proceed this kind of evaluation further, a five-wavelength photometer was developed and installed at the EISCAT Tromsoe site in January 2017 (Nozawa et al., 2018). The photometer is capable of simultaneously observing auroral emissions with five-wavelengths (427.8 nm, 557.7 nm, 630 nm, 777.4 nm, and 844.6 nm) with the FOV of about 1.0 degree. An unprecedented uniqueness of the new photometer is its capability of precise pointing, which enables pointing the photometer at the field-aligned position using a starry image obtained with a coaxial digital camera. We have collected simultaneous observational data of the photometer and the EISCAT UHF radar since November 2017. In this comparison, we have classified an auroral class by following the method of Nanjo et al. (2022) using collocated all-sky digital camera image data. In this talk, we will present comparisons between the photometer and the EISCAT radar data for different auroral conditions.
REFERENCE:
Adachi, K., S. Nozawa, Y. Ogawa, A. Brekke, C. M. Hall, R. Fujii, Evaluation of a method to derive ionospheric conductivities using two auroral emissions (428 and 630 nm) measured with a photometer at Tromsoe (69.6 deg N), EPS, 69: 90. doi:10.1186/s40623-017-0677-4, 2017.
Nanjo, S., S. Nozawa, M. Yamamoto, T. Kawabata, M. G. Johnsen, T. T. Tsuda, and K. Hosokawa, An Automated Auroral Detection System Using Deep Learning: Real-time Operation in Tromsoe, Norway, Scientific Reports, DOI: 10.1038/s41598-022-11686-8, 2022.
Nozawa, S., T. Kawabata, K. Hosokawa, Y. Ogawa, T. Tsuda, A. Mizuno, R. Fujii, and C. Hall, A new five-wavelength photometer operated in Tromsø (69.6 deg N, 19.2 deg E), EPS 10.1186/s40623-018-0962-x, 70:193, 2018.
Ono T., Derivation of energy parameters of precipitating auroral electrons by using the intensity ratios of auroral emissions, JGG, 45:455–472, 1993.
Robinson R.M., Vondrak R.R., Validation of techniques for space based remote sensing of auroral precipitation and its ionospheric effects, Space Sci Rev 69:331–407, 1994
To proceed this kind of evaluation further, a five-wavelength photometer was developed and installed at the EISCAT Tromsoe site in January 2017 (Nozawa et al., 2018). The photometer is capable of simultaneously observing auroral emissions with five-wavelengths (427.8 nm, 557.7 nm, 630 nm, 777.4 nm, and 844.6 nm) with the FOV of about 1.0 degree. An unprecedented uniqueness of the new photometer is its capability of precise pointing, which enables pointing the photometer at the field-aligned position using a starry image obtained with a coaxial digital camera. We have collected simultaneous observational data of the photometer and the EISCAT UHF radar since November 2017. In this comparison, we have classified an auroral class by following the method of Nanjo et al. (2022) using collocated all-sky digital camera image data. In this talk, we will present comparisons between the photometer and the EISCAT radar data for different auroral conditions.
REFERENCE:
Adachi, K., S. Nozawa, Y. Ogawa, A. Brekke, C. M. Hall, R. Fujii, Evaluation of a method to derive ionospheric conductivities using two auroral emissions (428 and 630 nm) measured with a photometer at Tromsoe (69.6 deg N), EPS, 69: 90. doi:10.1186/s40623-017-0677-4, 2017.
Nanjo, S., S. Nozawa, M. Yamamoto, T. Kawabata, M. G. Johnsen, T. T. Tsuda, and K. Hosokawa, An Automated Auroral Detection System Using Deep Learning: Real-time Operation in Tromsoe, Norway, Scientific Reports, DOI: 10.1038/s41598-022-11686-8, 2022.
Nozawa, S., T. Kawabata, K. Hosokawa, Y. Ogawa, T. Tsuda, A. Mizuno, R. Fujii, and C. Hall, A new five-wavelength photometer operated in Tromsø (69.6 deg N, 19.2 deg E), EPS 10.1186/s40623-018-0962-x, 70:193, 2018.
Ono T., Derivation of energy parameters of precipitating auroral electrons by using the intensity ratios of auroral emissions, JGG, 45:455–472, 1993.
Robinson R.M., Vondrak R.R., Validation of techniques for space based remote sensing of auroral precipitation and its ionospheric effects, Space Sci Rev 69:331–407, 1994