2. Aeronomy

Survey of conditions for artificial aurora experiments by the second electron gyro-harmonic at EISCAT Tromsø using dynasonde data

We report a brief survey of matching conditions for artificial aurora optical experiments utilizing the second electron gyro-harmonic (2.7-MHz frequency) in F region heating with O-mode at the EISCAT Tromsø site ...

Authors: T. T. Tsuda, M. T. Rietveld, M. J. Kosch, S. Oyama, Y. Ogawa, K. Hosokawa, S. Nozawa, T. Kawabata and A. Mizuno

Spatial distribution of errors associated with multistatic meteor radar

With the recent increase in numbers of small and versatile low-power meteor radars, the opportunity exists to benefit from simultaneous application of multiple systems spaced by only a few hundred km and less....

Authors: W. K. Hocking

El Niño–Southern Oscillation effect on quasi-biennial oscillations of temperature diurnal tides in the mesosphere and lower thermosphere

In this study, we evaluate the El Niño–Southern Oscillation (ENSO) signals in the two dominant temperature diurnal tides, diurnal westward wavenumber 1 (DW1) and diurnal eastward wavenumber 3 (DE3) on the quas...

Authors: Yang-Yi Sun, Huixin Liu, Yasunobu Miyoshi, Libo Liu and Loren C. Chang

Mesospheric radar wind comparisons at high and middle southern latitudes

We compare hourly averaged neutral winds derived from two meteor radars operating at 33.2 and 55 MHz to estimate the errors in these measurements. We then compare the meteor radar winds with those from a mediu...

Authors: Iain M. Reid, Daniel L. McIntosh, Damian J. Murphy and Robert A. Vincent

Data assimilation experiment of precipitable water vapor observed by a hyper-dense GNSS receiver network using a nested NHM-LETKF system

We studied the assimilation of high-resolution precipitable water vapor (PWV) data derived from a hyper-dense global navigation satellite system network around Uji city, Kyoto, Japan, which had a mean inter-st...

Authors: Masanori Oigawa, Toshitaka Tsuda, Hiromu Seko, Yoshinori Shoji and Eugenio Realini

Effect of enhanced ionizing radiation on the cloud electricity after the Fukushima nuclear accident

The vertical downward component of the DC atmospheric electric field, or potential gradient (PG), at Kakioka 150 km southwest of the Fukushima Dai-ichi Nuclear Power Plant (FNPP1) was analyzed before and after...

Authors: Masatoshi Yamauchi, Masahiko Takeda and Shingo Nagamachi

Survey of conditions for artificial aurora experiments at EISCAT Tromsø using dynasonde data

We report a brief survey on conditions for artificial aurora optical experiments in F region heating with O-mode at the EISCAT Tromsø site using dynasonde data from 2000 to 2017. The results obtained in our surve...

Authors: T. T. Tsuda, M. T. Rietveld, M. J. Kosch, S. Oyama, K. Hosokawa, S. Nozawa, T. Kawabata, A. Mizuno and Y. Ogawa

Ultraviolet imager on Venus orbiter Akatsuki and its initial results

The ultraviolet imager (UVI) has been developed for the Akatsuki spacecraft (Venus Climate Orbiter mission). The UVI takes ultraviolet (UV) images of the solar radiation reflected by the Venusian clouds with nar...

Authors: Atsushi Yamazaki, Manabu Yamada, Yeon Joo Lee, Shigeto Watanabe, Takeshi Horinouchi, Shin-ya Murakami, Toru Kouyama, Kazunori Ogohara, Takeshi Imamura, Takao M. Sato, Yukio Yamamoto, Tetsuya Fukuhara, Hiroki Ando, Ko-ichiro Sugiyama, Seiko Takagi, Hiroki Kashimura…

Retrieval of temperature profiles using radio acoustic sounding system (RASS) with the equatorial atmosphere radar (EAR) in West Sumatra, Indonesia

The radio acoustic sounding system (RASS) with the equatorial atmosphere radar (EAR) at Koto Tabang, Indonesia was adapted to test the effects of the acoustic source location and acoustic frequency range on th...

Authors: Ina Juaeni, Hiraku Tabata, Noersomadi, Halimurrahman, Hiroyuki Hashiguchi and Toshitaka Tsuda

Prediction of global ionospheric VTEC maps using an adaptive autoregressive model

In this contribution, an adaptive autoregressive model is proposed and developed to predict global ionospheric vertical total electron content maps (VTEC). Specifically, the spherical harmonic (SH) coefficient...

Authors: Cheng Wang, Shaoming Xin, Xiaolu Liu, Chuang Shi and Lei Fan

Short-term stratospheric ozone fluctuations observed by GROMOS microwave radiometer at Bern

The ground-based millimeter wave ozone spectrometer (GROMOS) has been continually measuring middle atmospheric ozone volume mixing ratio profiles above Bern, Switzerland ( ...

Authors: Lorena Moreira, Klemens Hocke and Niklaus Kämpfer

Midlatitude sporadic-E episodes viewed by L-band split-spectrum InSAR

Sporadic-E (Es) is a layer of ionization that irregularly appears within the E region of the ionosphere and is known to generate an unusual propagation of very high frequency waves over long distances. The det...

Authors: Masato Furuya, Takato Suzuki, Jun Maeda and Kosuke Heki

PCA and vTEC climatology at midnight over mid-latitude regions

The effect of the thermospheric vertical neutral wind on vertical total electron content (vTEC) variations including longitudinal anomaly, remaining winter anomaly, mid-latitude summer night anomaly, and semia...

Authors: M. P. Natali and A. Meza

Medium-scale traveling ionospheric disturbances over Taiwan observed with HF Doppler sounding

We analyzed horizontal velocities of medium-scale traveling ionospheric disturbances using HF Doppler sounding over Taiwan from January 2014 to January 2016. Meridional components of the observed horizontal ve...

Authors: Jiří Fišer, Jaroslav Chum and Jann-Yenq Liu

Comparison of three retrievals of COSMIC GPS radio occultation results in the tropical upper troposphere and lower stratosphere

Combining geometrical optics (GO) and wave optics (WO), the COSMIC data analysis and archive center (CDAAC) retrieved two sets of dry atmosphere temperatures (T) from COSMIC GPS radio occultation (GPS-RO), which ...

Authors: Noersomadi and Toshitaka Tsuda

Geomagnetically conjugate observations of ionospheric and thermospheric variations accompanied by a midnight brightness wave at low latitudes

We conducted geomagnetically conjugate observations of 630-nm airglow for a midnight brightness wave (MBW) at Kototabang, Indonesia [geomagnetic latitude (MLAT): 10.0°S], and Chiang Mai, Thailand (MLAT: 8.9°N)...

Authors: D. Fukushima, K. Shiokawa, Y. Otsuka, M. Kubota, T. Yokoyama, M. Nishioka, S. Komonjinda and C. Y. Yatini

Evaluation of a method to derive ionospheric conductivities using two auroral emissions (428 and 630 nm) measured with a photometer at Tromsø (69.6°N)

This paper mainly aims at evaluating capabilities of derivation of ionospheric conductivities using two principal auroral emissions (427.8 and 630 nm). We have evaluated a photometric method of derivation of i...

Authors: Kazuhiro Adachi, Satonori Nozawa, Yasunobu Ogawa, Asgeir Brekke, Chris Hall and Ryoichi Fujii

Magnetic ripples observed by Swarm satellites and their enhancement during typhoon activity

The Swarm satellites observed small-amplitude (0.1–5 nT) magnetic fluctuations perpendicular to the geomagnetic field. These so-called magnetic ripples (MRs) have a period of around a few tens of seconds along...

Authors: Tadashi Aoyama, Toshihiko Iyemori and Kunihito Nakanishi

Measurement of thermospheric temperatures using OMTI Fabry–Perot interferometers with 70-mm etalon

Fabry–Perot interferometer (FPI) is an instrument that can measure the temperature and wind velocity of the thermosphere through observations of airglow emission at a wavelength of 630.0 nm. The Solar-Terrest...

Authors: Y. Nakamura, K. Shiokawa, Y. Otsuka, S. Oyama, S. Nozawa, T. Komolmis, S. Komonjida, Dave Neudegg, Colin Yuile, J. Meriwether, H. Shinagawa and H. Jin

Sensitivity of ionosonde detection of atmospheric disturbances induced by seismic Rayleigh waves at different latitudes

Authors: Takashi Maruyama, Hiroyuki Shinagawa, Kamil Yusupov and Adel Akchurin

Competition between winds and electric fields in the formation of blanketing sporadic E layers at equatorial regions

In the present work, we analyze the competition between tidal winds and electric fields in the formation of blanketing sporadic E layers (Es_b) over São Luís, Brazil (2° 31′ S, 44° 16′ W), a quasi-equatorial stati...

Authors: Laysa Cristina Araújo Resende, Inez Staciarini Batista, Clezio Marcos Denardini, Alexander José Carrasco, Vânia de Fátima Andrioli, Juliano Moro, Paulo Prado Batista and Sony Su Chen

First imaging and identification of a noctilucent cloud from multiple sites in Hokkaido (43.2–44.4°N), Japan

Simultaneous imaging observations of a noctilucent cloud (NLC) from five sites in Hokkaido, Japan (43.17–45.36°N), were successfully carried out using digital cameras in the early hours of the morning (around ...

Authors: Hidehiko Suzuki, Kazuyo Sakanoi, Nozomu Nishitani, Tadahiko Ogawa, Mitsumu K. Ejiri, Minoru Kubota, Takenori Kinoshita, Yasuhiro Murayama and Yasushi Fujiyoshi

Statistical analysis of the mid-latitude trough position during different categories of magnetic storms and different storm intensities

The ionospheric mid-latitude trough minimum position as a function of geomagnetic storm time is identified and investigated statistically in terms of the category and the intensity of storms. The data of ion d...

Authors: Na Yang, Huijun Le and Libo Liu

Calibration of imaging parameters for space-borne airglow photography using city light positions

A new method for calibrating imaging parameters of photographs taken from the International Space Station (ISS) is presented in this report. Airglow in the mesosphere and the F-region ionosphere was captured on t...

Authors: Yuta Hozumi, Akinori Saito and Mitsumu K. Ejiri

Localized field-aligned currents and 4-min TEC and ground magnetic oscillations during the 2015 eruption of Chile’s Calbuco volcano

The Calbuco volcano in southern Chile erupted on April 22, 2015. About 2 h after the first eruption, a Swarm satellite passed above the volcano and observed enhancement of small-amplitude (~0.5 nT) magnetic fl...

Authors: Tadashi Aoyama, Toshihiko Iyemori, Kunihito Nakanishi, Michi Nishioka, Domingo Rosales, Oscar Veliz and Erick Vidal Safor

An overview of VHF lightning observations by digital interferometry from ISS/JEM-GLIMS

The Global Lightning and sprIte MeasurementS (GLIMS) mission has been conducted at the Exposed Facility of Japanese Experiment Module (JEM-EF) of the International Space Station for more than 30 months. This p...

Authors: Takeshi Morimoto, Hiroshi Kikuchi, Mitsuteru Sato, Tomoo Ushio, Atsushi Yamazaki, Makoto Suzuki, Ryohei Ishida, Yuji Sakamoto, Kazuya Yoshida, Yasuhide Hobara, Takuki Sano, Takumi Abe and Zen-Ichiro Kawasaki

Sunlight effects on the 3D polar current system determined from low Earth orbit measurements

Interaction between the solar wind and the Earth’s magnetosphere is associated with large-scale currents in the ionosphere at polar latitudes that flow along magnetic field lines (Birkeland currents) and horiz...

Authors: Karl M. Laundal, Christopher C. Finlay and Nils Olsen

Scale analysis of equatorial plasma irregularities derived from Swarm constellation

In this study, we investigated the scale sizes of equatorial plasma irregularities (EPIs) using measurements from the Swarm satellites during its early mission and final constellation phases. We found that wit...

Authors: Chao Xiong, Claudia Stolle, Hermann Lühr, Jaeheung Park, Bela G. Fejer and Guram N. Kervalishvili

Phase space representation of neutron monitor count rate and atmospheric electric field in relation to solar activity in cycles 21 and 22

Heliospheric modulation of galactic cosmic rays links solar cycle activity with neutron monitor count rate on earth. A less direct relation holds between neutron monitor count rate and atmospheric electric fie...

Authors: H. G. Silva and I. Lopes

The role of high-resolution geomagnetic field models for investigating ionospheric currents at low Earth orbit satellites

Low Earth orbiting geomagnetic satellite missions, such as the Swarm satellite mission, are the only means to monitor and investigate ionospheric currents on a global scale and to make in situ measurements of ...

Authors: Claudia Stolle, Ingo Michaelis and Jan Rauberg

Influence of uncertainties of the empirical models for inferring the E-region electric fields at the dip equator

Daytime E-region electric fields play a crucial role in the ionospheric dynamics at the geomagnetic dip latitudes. Due to their importance, there is an interest in accurately measuring and modeling the electr...

Authors: Juliano Moro, Clezio Marcos Denardini, Laysa Cristina Araújo Resende, Sony Su Chen and Nelson Jorge Schuch

On forced and free atmospheric oscillations near the 27-day periodicity

The Whole Atmosphere Community Climate Model was used to investigate the influences of solar fluctuations on zonal wind oscillations. Two simulations were conducted with short-term solar forcing (<35 days) on ...

Authors: Ansgar Schanz, Klemens Hocke and Niklaus Kämpfer

Characterising the three-dimensional ozone distribution of a tidally locked Earth-like planet

We simulate the 3D ozone distribution of a tidally locked Earth-like exoplanet using the high-resolution, 3D chemistry-climate model CESM1(WACCM) and study how the ozone layer of a tidally locked Earth (TLE) (

Authors: Elisavet Proedrou and Klemens Hocke

Swarm accelerometer data processing from raw accelerations to thermospheric neutral densities

The Swarm satellites were launched on November 22, 2013, and carry accelerometers and GPS receivers as part of their scientific payload. The GPS receivers do not only provide the position and time for the mag...

Authors: Christian Siemes, João de Teixeira da Encarnação, Eelco Doornbos, Jose van den IJssel, Jiří Kraus, Radek Pereštý, Ludwig Grunwaldt, Guy Apelbaum, Jakob Flury and Poul Erik Holmdahl Olsen

Occurrence of the blanketing sporadic E layer during the recovery phase of the October 2003 superstorm

We have routinely monitored the total frequency (ftEs) and the blanketing frequency (fbEs) of sporadic E layers with the digital sounder under the magnetic equator in the Brazilian sector. Sporadic layers appear ...

Authors: Clezio Marcos Denardini, Laysa Cristina Araújo Resende, Juliano Moro and Sony Su Chen

Thermospheric inter-annual variability and its potential connection to ENSO and stratospheric QBO

Using a 46-year-long dataset of the thermospheric density during 1967–2012, we examined the inter-annual variability in the thermosphere at 400 km and its potential connection to El-Nino Southern Oscillation (...

Authors: Huixin Liu

Observations of stratospheric and mesospheric O₃ with a millimeter-wave radiometer at Rikubetsu, Japan

We have been measuring brightness temperature spectra of the atmospheric ozone (O₃) emission at 110.83 GHz with a millimeter-wave radiometer (MWR) located at Rikubetsu, Japan, since November 1999. Tropospheric o...

Authors: Hirofumi Ohyama, Tomoo Nagahama, Akira Mizuno, Hideaki Nakane and Hideo Ogawa

Ionospheric signatures of the April 25, 2015 Nepal earthquake and the relative role of compression and advection for Doppler sounding of infrasound in the ionosphere

Ionospheric signatures possibly induced by the Nepal earthquake are investigated far outside the epicentral region in Taiwan (~3700 km distance from the epicenter) and in the Czech Republic (~6300 km distance ...

Authors: Jaroslav Chum, Jann-Yenq Liu, Jan Laštovička, Jiří Fišer, Zbyšek Mošna, Jiří Baše and Yang-Yi Sun

Statistical analysis of extreme auroral electrojet indices

Extreme auroral electrojet activities can damage electrical power grids due to large induced currents in the Earth, degrade radio communications and navigation systems due to the ionospheric disturbances and c...

Authors: Masao Nakamura, Asato Yoneda, Mitsunobu Oda and Ken Tsubouchi

Approaches for modeling ionosphere irregularities based on the TEC rate index

The ionosphere plays an important role in GNSS applications because it influences radio wave propagation. The ionospheric delay is the biggest error source for satellite navigation signals, but it can be direc...

Authors: Iurii Cherniak, Irina Zakharenkova and Andrzej Krankowski

Long-term variation in the upper atmosphere as seen in the geomagnetic solar quiet daily variation

Characteristics of long-term variation in the amplitude of solar quiet (Sq) geomagnetic field daily variation have been investigated using 1-h geomagnetic field data obtained from 69 geomagnetic observation st...

Authors: Atsuki Shinbori, Yukinobu Koyama, Masahito Nose, Tomoaki Hori, Yuichi Otsuka and Akiyo Yatagai

A statistical study of satellite traces and evolution of equatorial spread F

The ionosonde observations made at 5-min intervals at the Indian dip equatorial station Tirunelveli (8.7°N, 77.8°E geographic; 1.1°N dip latitude) from March 2008 to February 2009 during the extended solar min...

Authors: Viswanathan Lakshmi Narayanan, Sukanta Sau, Subramanian Gurubaran, Kazuo Shiokawa, Nanan Balan, Kaliappan Emperumal and Samireddipalle Sripathi

Reaction of electric and meteorological states of the near-ground atmosphere during a geomagnetic storm on 5 April 2010

The effects of a geomagnetic storm on 5 April 2010 on electric parameters of the atmospheric near-ground layer in Kamchatka have been investigated. Three processes over the course of the storm were identified....

Authors: Sergey Smirnov

Methods of analysis of geomagnetic field variations and cosmic ray data

In the present paper, we propose a wavelet-based method of describing variations in the Earth’s magnetic field, such as the horizontal component of the geomagnetic field, in addition to methods for evaluating ...

Authors: Oksana V Mandrikova, Igor S Solovev and Timur L Zalyaev

Lidar returns from the upper atmosphere of Kamchatka for 2008 to 2014 observations

The correlation of lidar returns at a wavelength of 532 nm at altitudes of 150 to 300 km is investigated with the parameters of the night ionospheric F2 layer. Moreover, the role of excited ions of the nitroge...

Authors: Vasily V Bychkov, Yuri А Nepomnyashchiy, Andrey S Perezhogin and Boris M Shevtsov

Investigation of the intraseasonal oscillations over a Brazilian equatorial station: a case study

Characteristics of the intraseasonal oscillations (ISO) in the mesosphere and lower thermosphere (MLT) are investigated using meteor radar wind observations from a South American, equatorial station, São João ...

Authors: Amitava Guharay, Paulo Prado Batista, Barclay Robert Clemesha, Sumanta Sarkhel and Ricardo Arlen Buriti

Correlation between the global occurrences of ionospheric irregularities and deep atmospheric convective clouds in the intertropical convergence zone (ITCZ)

To study the seeding mechanism of ionospheric irregularity occurrences, a correlation study has been carried out between the global monthly/latitudinal (m/l) distributions of irregularity occurrences and the d...

Authors: Shin-Yi Su, Chung Lung Wu and Chao Han Liu

New perspectives on thermosphere tides: 1. Lower thermosphere spectra and seasonal-latitudinal structures

Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry (TIMED/SABER) temperature measurements at 110 km and between ±50° latitude extending fr...

Authors: Alexander O Truskowski, Jeffrey M Forbes, Xiaoli Zhang and Scott E Palo

Relationship between the equatorial electrojet and global Sq currents at the dip equator region

The equatorial electrojet (EEJ) is a strong eastward ionospheric current flowing in a narrow band along the dip equator. In this study, we examined the EEJ-Sq relationship by using observations at six stations...

Authors: Nurul Shazana Abdul Hamid, Huixin Liu, Teiji Uozumi, Kiyohumi Yumoto, Bhaskara Veenadhari, Akimasa Yoshikawa and Jairo Avendaño Sanchez

Ionospheric current contribution to the main impulse of a negative sudden impulse

The geomagnetic field response to a moderate-amplitude negative sudden impulse (SI⁻) that occurred on 14 May 2009 at 10:30 UT was examined at 97 geomagnetic observatories situated all over the globe. The response...

Authors: Geeta Vichare, Rahul Rawat, Ankush Bhaskar and Bashir M Pathan