PEM06-01

Room:A01

Time:May 26 16:15-16:45

Recent advances in the low latitude ionospheric irregularities- a review
PATRA, Amit1∗ ; OTSUKA, Yuichi2
1

National Atmospheric Research Laboratory, 2 Solar-Terrestrial Environment Laboratory

Scientific research on the low latitude ionospheric irregularities continues to be of interest due to their adverse effects oncommunication and navigation systems. Understanding the physical processes and governing free energy sources leading todevelop forecasting capability is the current focus. Low latitude ionospheric E and F regions become unstable both during day
and night and irregularities are formed at different height regions. While understanding the F region processes with forcing
from below and extra-tropics has been paid attention, research activities are also focused on understanding fascinating detailsof E- and valley- region plasma processes, such as instabilities linked with tidal ion layer, intermediate layer and daytime 150
km echoes. Recent experiments conducted from low latitudes in the Asian sector have added new observational knowledge
on plasma irregularities. This paper will present the recent advancements made in understanding E and F region irregularities
including coupling between the two regions and daytime 150 km irregularities based on observations made in the Asian sector.

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PEM06-02

Room:A01

Time:May 26 16:45-17:00

Three-dimensional plasma bubble simulation driven by whole atmosphere-ionosphere
coupled model
YOKOYAMA, Tatsuhiro1∗ ; SHINAGAWA, Hiroyuki1 ; JIN, Hidekatsu1
1

National Institute of Information and Communications Technology

Equatorial plasma bubble (EPB) is a well-known phenomenon in the equatorial ionospheric F region. As it causes severe
scintillation in the amplitude and phase of radio signals, it is important to understand and forecast the occurrence of EPB froma space weather point of view. The development of EPB is known as a evolution of the generalized Rayleigh-Taylor instability.
Numerical modelings of the instability on the equatorial two-dimensional plane have been conducted since the late 1970’s, andthe nonlinear evolution of the instability has been clearly presented. Recently, three-dimensional (3D) modelings became popular
tools for further understanding of the development of EPB such as 3D structure of EPB, meridional wind effects and gravity wave
seeding.
We have developed a new 3D high-resolution bubble (HIRB) model for EPB and presented nonlinear growth of EPB whichshows very turbulent internal structures such as bifurcation and pinching. The eastward neutral wind in the evening produced
reverse-C shape of EPB as frequently observed by various instruments. We are trying to integrate the high-resolution model for
EPB with the whole atmosphere-ionosphere coupled model (GAIA) to study the growth of EPB under the realistic backgroundconditions. The background electric field and neutral wind partially controlled by forcing from the lower atmosphere may cause
the day-to-day variability of EPB occurrence.

Keywords: plasma bubble, equatorial ionosphere, simulation, GAIA model, HIRB model

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PEM06-03

Room:A01

Time:May 26 17:00-17:15

Predawn depletion observed by GRBR and GPS networks in Southeast Asia
WATTHANASANGMECHAI, Kornyanat1∗ ; YAMAMOTO, Mamoru1 ; SAITO, Akinori2 ; YOKOYAMA, Tatsuhiro3
1

Research Institute for Sustainable Humanosphere, Kyoto University, 2 Department of Geophysics, Graduate School of Science,
Kyoto University, 3 National Institute of Information and Communications Technology
Deep plasma depletion during substorm at predawn (0412-0436 LT) on 6 March 2012 was captured by GRBR network andwas confirmed by sparse GPS networks in Southeast Asia. The only available low-Earth-orbit (LEO) satellite during the event
is DMSPF15 with NE-to-SW overpass. GRBR network covering both hemispheres is aligned along the ˜100 E meridian. GPS
network including 12 GPS receivers sparsely distributes from 25 N to 1 N and from 99 E to 105 E. The supporting information
includes in-situ ion density data from DMSPF15 satellite, bottomside ionospheric data from ionosonde at Chumphon (10.72
N, 99.37 E) and data from the EAR at Kototabang (0.20 S, 100.32 E). This event was recognized by GRBR-TEC as having asteep TEC gradient that can trouble in positioning error on the aeronautical augmentation system. This finding was supported by
the GPS-TEC. In addition to the depletion, the GPS-TEC revealed the co-locating sub-mesoscale Medium-Scale-IonosphericDisturbance-like (MSTID-like) structures. Because the sparseness of the observation points has restricted the resolution of
the observations, several assumptions are necessary to interpret the data, such as the neglect of the temporal variations of theirstructures. As a result, a deep plasma depletion event was understood as having fossil plasma bubbles and sub-mesoscale MSTIDlike structures collocating. The wavefront of the plasma bubbles and the MSTID-like structures are found to be the same. This
event improves the predawn ionospheric information over Southeast Asia and is significant for being the prior-knowledge for theionospheric modeling.
Keywords: TEC, GRBR, GPS, predawn depletion, plasma bubble, Southeast Asia

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PEM06-04

Room:A01

Time:May 26 17:15-17:30

Effects of Pre-reversal Enhancement of E x B drift on the Latitudinal Extension of Plasma
Bubble in Southeast Asia
ABADI, Prayitno1∗ ; OTSUKA, Yuichi1 ; TSUGAWA, Takuya2 ; YOKOYAMA, Tatsuhiro2
1

Solar Terrestrial Environment Laboratory (STEL), Nagoya University, 2 National Institute of Information and Communication
Technology (NICT)
We investigated the effects of the F region bottomside altitude (h’F), maximum eastward electric field (E), duration of eastward
E, and the integral of eastward E on the latitudinal extension of equatorial plasma bubbles in the Southeast Asian sector using
the observations recorded by three GPS receivers and two ionosondes. The GPS receivers are installed at Kototabang (0.2 deg S,
100.3 deg E; 10.0 deg N magnetic latitude), Pontianak (0.02 deg S, 109.3 deg E; 8.9 deg S magnetic latitude), and Bandung (6.9
deg S, 107.6 deg E; 17.5 deg S magnetic latitude) in Indonesia. The ionosondes are installed at equatorial stations Chumphon(10.7 deg N, 99.4 deg E; 3.3 deg N magnetic latitude) in Thailand and Bac Lieu (9.3 deg N, 105.7 deg E; 1.7 deg N magnetic
latitude) in Vietnam. We analysed those observations acquired in the equinoctial months (March, April, September, and October)in 2010?2012 when the solar activity index F10.7 was in the range from 75 to 150. Assuming that plasma bubbles are the major
source of scintillations, the latitudinal extension of the bubbles was determined according to the S4 index. Our results show thatthe peak of h’F, maximum eastward E within the pre-reversal enhancement period, and the integral of eastward E are positively
correlated with the maximum latitude extension of plasma bubbles. Our statistical and observational findings emphasise thatplasma bubble extending more than 10?18 deg in latitude from the magnetic equator can be generated when the peak valueof h’F is greater than 250?450 km, the maximum vertical upward E x B drift is greater than 10?70 m/s, and the integral ofvertical upward E x B drift is greater than 50?250 m/s. In contrast, the duration of eastward E shows only weak correlation withthe maximum latitude extension of plasma bubbles. These findings suggest that the latitudinal extension of plasma bubbles iscontrolled mainly by the magnitude of eastward E and the peak value of h’F at the initial phase of development of plasma bubbles(or equatorial spread F) rather than by the duration of eastward E.
Keywords: equatorial ionosphere, plasma bubble, pre-reversal enhancement, scintillation

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PEM06-05

Room:A01

Time:May 26 17:30-17:45

Temperature trend of electron and ion with plasma density in middle and low latitude in
the topside ionosphere
KAKINAMI, Yoshihiro1∗ ; WATANABE, Shigeto2 ; LIU, Huixin3
1

Kochi University of Technology, 2 Hokkaido Information University, 3 Kyuhsu University

It is important to understand energy flow from electron to ion and neutral species because main heat source of ionosphericplasma is photoelectron created by solar EUV. First, electrons are heated by photoelectrons, then heated electrons reduce theirenergy through the Column collision with ions. Finally, ions are cooled by inelastic collision with neutral species. Temperaturesof electron (Te), ion (Ti) and neutral species (Tn) get close to each other during night time due to lack of significant heat source.
Heating rate of electron by photoelectron is proportion to ambient plasma density while cooling rate of electron is proportion tosquare of the plasma density. Therefore, Te decreases with increase of electron density (Ne) in general. However, some satellite
results show Te increases with increase of Ne when Ne is high enough (more than about 106 cm−3 ). To understand the unexpected
Te, it is also important to know Ti variation because ion plays as a heat sink of electron. In this paper, we summarized correlationof Ne with Te and Ti observed by HINOTORI, CHAMP and ROCSAT-1 in the topside ionosphere. Since these satellites did notobserve Te and Ti simultaneously, Te, Ti and Ne measured with the incoherent scatter radars at Jicamaruca and Millstone Hill
are also shown. Using these data, we discuss possible cause of unexpected high Te in high Ne region.
Keywords: topside ionsophere, electron temperature, electron density, ion temperature, photoelectron, middle and low latitude

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PEM06-06

Room:A01

Time:May 27 09:00-09:30

Climatology of gravity waves in the mesosphere observed with the MU radar
RIGGIN, Dennis1∗
1

GATS Inc.

The MU radar at Shigaraki, Japan has been operating periodically since 1986 and the extensive data set provides a unique
opportunity to study the seasonal variations of gravity waves. The data has recently been made available publicly to the scientificcommunity through a link in a large meta-database called IUGONET (Inter-university Upper atmosphere Global Observation
NETwork). In our study we focus on gravity waves observed during daylight hours between 60 and 97 km. Several days ofobservations were made during most months during the 29 years of operation. We calculate the vertical fluxes of horizontal
momentum and quantify the statistical characteristics and temporal variabilityof the waves. The spatial scales and intrinsic wave
properties are determined, as well as their response to seasonal changes in the background conditions. The background conditions
considered include changes in the mean horizontal winds and the atmospheric static stability. This study differs from those done
previously in that we make extensive use of probablity distribution functions as a complement to spectral analysis.
Keywords: mesosphere, gravity waved, climatology, Mu radar

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PEM06-07

Room:A01

Time:May 27 09:30-09:45

On the coupling between gravity waves and background field including tides observedwith MF radar at Poker Flat & Tromso
KINOSHITA, Takenari1∗ ; MURAYAMA, Yasuhiro1 ; KAWAMURA, Seiji1 ; NOZAWA, Satonori2 ; HALL, Chris3
1

NICT, 2 Nagoya University, 3 The Arctic University of Norway

The neutral wind velocity data from mesosphere to lower thermosphere observed by MF radars at Poker Flat in Alaska andat Tromso in Norway has been observed since the late 1990s. The present study examines the daily and seasonal variations ofshort-period mesospheric gravity wave activities associated with the background state including tides using these MF radars’
data for 10 years of 1999?2008.
Observed wind velocities having the 1˜4 hour period components are analyzed as short-period gravity waves and those having
harmonic components with periods of 24, 12, and 8 hours are calculated every 30 minutes. The previous study in AGU2014
showed that the semidiurnal phases of zonal wind and kinetic energy of gravity waves (GW-KE) are locked for more than 10
days. Such phase lock events are found in several years at both observation sites. It is confirmed a phase lock phenomena at both
Tromso and Poker Flat continued for about 20 days from November to December in 2000. However, between Tromso and Poker
Flat, the phases of 12 hour component of GW-KE differed by 180 degrees. Next, we made climatological 1-day composite plotsof semidiurnal components of zonal wind and GW-KE. The result showed that the maximum of GW-KE occurs at Poker Flat
when zonal wind is westward from November to December and zonal wind transitions from westward to eastward from January
to February and from May to August. The results of Tromso showed that the maximum of GW-KE occurs at local time whenzonal wind is eastward from November to February and westward from May to September. Thus, it is suggested that the observed
phase lock event is possibly to be occurred fluently. We plan to investigate the relations between other harmonic components ofzonal wind and GW-KE and discuss the physical mechanism of the relations.
Keywords: middle atmosphere, gravity waves, tidal waves

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PEM06-08

Room:A01

Time:May 27 09:45-10:00

Distributions of horizontal phase velocity of gravity waves observed by ANGWIN, using
a 3-D spectral analysis technique
MATSUDA, Takashi S.1∗ ; NAKAMURA, Takuji2 ; EJIRI, Mitsumu K.2 ; TSUTSUMI, Masaki2 ;TAYLOR, Michael J.3 ; ZHAO, Yucheng3 ; PAUTET, P.-dominique3 ; MURPHY, Damian4 ;MOFFAT-GRIFFIN, Tracy5
1
4

SOKENDAI (The Graduate University for Advanced Studies), 2 National Institute of Polar Research, 3 Utah State University,
Australian Antarctic Division, 5 British Antarctic Survey

Atmospheric gravity waves (AGWs), which are generated in the lower atmosphere, transport significant amount of energy
and momentum into the mesosphere and lower thermosphere and cause the mean wind accelerations in the mesosphere. This
momentum deposit drives the general circulation and affects the temperature structure. Among many parameters to characterize
AGWs, horizontal phase velocity is very important to discuss their vertical propagation. Airglow imaging is a useful techniquefor investigating the horizontal structures of AGWs around mesopause. An international airglow imager (and other instruments)
network in the Antarctic, named ANGWIN (Antarctic Gravity Wave Imaging/Instrument Network) was started in 2011. Its
purpose is to understand characteristics of mesospheric gravity waves, and to study sources, propagation, breaking of the gravity
waves over the Antarctic and the effects on general circulation and upper atmosphere.
In this study, we compared distributions of horizontal phase velocities of gravity waves at around 90 km altitude over different
locations using our new statistical analysis method based on 3-D Fourier transform, developed by Matsuda et al. (2014). The
comparison has been carried out for the airglow imagers at four stations, that are Syowa (69S, 40E), Halley (76S, 27W), Davis(69S, 78E) and McMurdo (78S, 156E) out of the ANGWIN imagers, for the observation period between April 6 and May 21
in 2013. Not only horizontal propagation characteristics, gravity wave energies can also be quantitatively compared, indicatinga smaller GW activity in higher latitudes. The presentation will be focused on showing the performance of the new statisticaltechnique for studying gravity waves.

Keywords: atmospheric gravity wave, airglow imaging

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PEM06-09

Room:A01

Time:May 27 10:00-10:15

Obervation of mesopause temperature by Kunming meteor radar
YI, Wen1∗
1

Department of Geophysics & Planetary Sciences, University of Science & Technology of China, 2 National Key Laboratory ofElectromagnetic Environment,Research Institute of Radiowave Propagation
A method to calibrate the initial temperatures derived from the meteor radar at Kunming in low latitudes area using SABER
temperatures is presented in this paper. Most of the meteors are observed in the local morning by Kunming meteor radar, therefore, the daily mean temperatures measured by the meteor radar were biased by local morning values. The daily temperatures
estimated using temperature gradient model technique are consistent well with the daily SABER temperatures which averaged
from 1600 to 0600 UT, but fluctuate greater than SABER temperatures. The correlation coefficient between the meteor and
SABER temperatures is 0.58. The Lomb Periodograms of meteor and SABER temperatures both exhibit clear seasonal andinterannual periodicities, with annual, semiannual, quasi 90 day and terannual oscillations. The results of harmonic fit analysis
show that the mean values are very close and these periodic oscillations have similar phases, however, the oscillation amplitudesof meteor temperatures are larger than SABER temperatures. The larger fluctuations of meteor temperatures were identified aslarger amplitude of the temperature oscillation components. Thus, the amplitude calibration was used to adjust the larger fluctuations of meteor temperatures. After temperature calibration was performed, the fluctuations of meteor and SABER temperatures
agree well, and the accuracy of the calibrated temperatures has been significantly improved. In addition, the temperatures determined by the temperature gradient model technique could effectively be used to study the waves and oscillations in the mesopause
region.
Keywords: meteor radar, mesopause temperature, temperature gradient, temperature oscillation

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PEM06-10

Room:A01

Time:May 27 10:15-10:30

Characteristics of long-term variation of the geomagnetic solar quiet daily variation
SHINBORI, Atsuki1∗ ; KOYAMA, Yukinobu2 ; NOSE, Masahito2 ; HORI, Tomoaki3 ; OTSUKA, Yuichi3 ;YATAGAI, Akiyo3
1

Research Institute for Sustainable Humanosphere (RISH), Kyoto University, 2 World Data Center for Geomagnetism, Kyoto
University, 3 Solar-Terrestrial Environment Laboratory, Nagoya University
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 stations within the period of 1947 - 2013.
The Sq amplitude observed at these geomagnetic stations showed a clear dependence on the 10 - 12 year solar activity cycle andtended to be enhanced during each solar maximum phase. The Sq amplitude was the smallest around the minimum of solar cycle
23/24 in 2008 - 2009. The relationship between the solar F10.7 index and Sq amplitude was approximately linear but about 53 %of geomagnetic stations showed a weak nonlinear relation to the solar F10.7 index. In order to remove the effect of solar activity
seen in the long-term variation of the Sq amplitude, we calculated a linear or second-order fitting curve between the solar F10.7
index and Sq amplitude during 1947 - 2013, and examined the residual Sq amplitude, which is defined as the deviation from thefitting curve. As a result, the majority of trends in the residual Sq amplitude that passed through a trend test showed negativevalues over a wide region. This tendency was relatively strong in Europe, India, the eastern part of Canada, and New Zealand.
The relationship between the magnetic field intensity at 100 km altitude and residual Sq amplitude showed an anti-correlation
for about 71 % of the geomagnetic stations. The decreasing trend of the residual Sq amplitude implies that the ionospheric Sq
current intensity tends to weaken due to a decrease of the ionospheric conductivity associated with an increase of the ambient
magnetic field intensity. Furthermore, the residual Sq amplitude at the equatorial station (Addis Ababa) was anti-correlated withthe absolute value of the magnetic field inclination. The decreasing trend of the residual Sq amplitude in the equatorial region
indicates movement of the equatorial electrojet due to the secular variation of the ambient magnetic field.
Keywords: Solar activity, Geomagnetic solar quiet daily variation, Ionospheric conductivity, Ionospheric dynamo, Secular variation of geomagnetic field, Thermospheric wind

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PEM06-11

Room:A01

Time:May 27 10:30-10:45

Equatorial MLT dynamics using long-term radar observation
MATSUMOTO, Naoki1∗ ; SHINBORI, Atsuki1 ; TSUDA, Toshitaka1
1

Research Institute for Sustainable Humanosphere

In the equatorial region, atmospheric waves cause the S-QBO(Stratospheric Quasi-Biennial Oscillation) in the lower stratosphere, S-SAO(Stratospheric Semi Annual Oscillation) in the upper stratosphere and M-SAO(Mesospheric Semi Annual Oscillation) in the MLT(Mesosphere Lower Thermosphere).S-SAO and M-SAO is opposite phase.
We investigate the periodic oscillation and random variation of wind in the MLT over equatorial region by using long-term
meteor radar observation in Indonesia. Especially, we focus on the peculiar phenomenon that enhance westward wind in Feb.Apr. once in 2 or 3 years, M-QBE(Mqsosphere Quasi-Biennial Enhancement).M-QBE occur only spring but not fall. We thinkthat there must be 1-year oscillation which restrict the M-QBE to spring.
N.V.Rao et al.[2012] reported that gravity wave enhancement coinside with westward wind enhancement. This result suggestthat gravity waves drive the M-QBE. However, we have to measure the momentum flux with gravity waves to reveal the relationship between M-QBE and gravity waves.
Hocking[2005] proposed a new method that enables us to measure the momentum flux by using meteor radar. However, thismethod has several doubtful points, so we checked the validation.
We have two meteor radars which have the same system and which are in the neighborhood in Indonesia(Koto Tabang andBiak) on the equator. We used these meteor radar data ,calculated the momentum flux, and checked the validation in Hocking
method.
We compared the data from two meteor radar, and we got the similar momentum flux results during high acquisition rate.
From this result, We are succeeded to measure the momentum flux by using the Hocking method.
On the other hand, we did a composit analysis in Koto Tabang which have 12 years long-term data. This composit analysis
suggests that the momentum flux has the periodicity of the half year. This result is consistent with M-SAO.

Keywords: Mesosphere and Lower Thermosphere, Quasi-biennual Oscillation, momentum flux, Hocking

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PEM06-12

Room:A01

Time:May 27 11:00-11:30

Deep ionospheric hole created by sudden stratospheric warming in the post-midnight
ionosphere
GONCHARENKO, Larisa1∗ ; COSTER, Anthea1 ; ZHANG, Shunrong1 ; ERICKSON, Phillip1 ; APONTE, Nestor2
1

Massachusetts Institute of Technology, Haystack Observatory, 2 Arecibo Observatory, SRI International

Multiple observational studies have demonstrated large ionospheric variations associated with sudden stratospheric warming(SSW) events during the daytime, but only limited evidence of ionospheric disturbances during the night-time was reported up
to now. We use observations by GPS TEC receivers and Arecibo and Millstone Hill incoherent scatter radars to investigate largescale disturbances in the nighttime ionosphere for several SSW events. We report a deep decrease in TEC that reaches ˜70%of the background level and is observed between the local midnight and local sunrise (6-12UT). This decrease is observed forseveral consecutive days in the range of latitudes from ˜60oS to ˜45oN. It is accompanied by a strong downward plasma motion
and significant decrease in ion temperature, as observed by both Arecibo and Millstone Hill radars. We discuss variations inelectric field and F-region dynamics as possible drivers of this behavior.
Keywords: sudden stratospheric warming, atmospheric coupling, ionosphere

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PEM06-13

Room:A01

Time:May 27 11:30-11:45

Spatial and temporal extent of ionospheric anomalies during sudden stratospheric warmings in the daytime ionosphere
GONCHARENKO, Larisa1∗ ; COSTER, Anthea1 ; ZHANG, Shunrong1 ; BENKEVITCH, Leonid1 ; GALKIN, Ivan2
1

Massachusetts Institute of Technology, Haystack Observatory, 2 University of Massachusetts, Lowell

Recent studies have demonstrated large variations in the daytime ionosphere during sudden stratospheric warmings (SSW)
and a debate has started about the relative importance of solar and lunar tides in these ionospheric variations. In this study
we use GPS TEC data from the MIT Haystack Observatory Madrigal database along 75o W collected in 2000-2014 as well as
several digisondes to examine the magnitude and spatio-temporal extent of ionospheric anomalies related to SSW. To separate
ionospheric anomalies during SSW from regular ionospheric behavior, we develop empirical models of ionospheric parameters(TEC, NmF2) using available long-term records. The models describe variations in parameters for each lon/lat bin (or digisonde
location) as a function of solar activity, geomagnetic activity, day of year, and local time. Ionospheric anomalies are obtained as
difference between observations and empirical model. Analysis of anomalies shows that they are observed for both major andminor SSW events, reaching 50-100% variation from expected seasonal behavior for major SSW events and 30-60% variation
for minor SSW events. SSW-associated variations are pronounced more strongly in NmF2 than in TEC. The largest variations in
TEC in the daytime are observed both in the crests of equatorial ionization anomaly and at 40-60o S (geodetic). Variations in TEC
and NmF2 are even discernable up to high latitudes (70o S) in the Southern Hemisphere and mid-latitudes (42o N) in the Northern
Hemisphere. We discuss several possible mechanisms contributing to these anomalies, focusing on solar and lunar semidiurnal
tides and interhemispheric coupling.

Keywords: sudden stratospheric warming, atmospheric coupling, ionosphere

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PEM06-14

Room:A01

Time:May 27 11:45-12:00

Longitudinal Variations of Low-Latitude Gravity Waves and Their Impacts on the Ionosphere
CULLENS, Chihoko1∗ ; ENGLAND, Scott1 ; IMMEL, Thomas1
1

University of California Berkeley

The lower atmospheric forcing has important roles in the ionospheric variability. Previous study suggested that atmospherictides from the troposphere induce the wavenumber 4 signatures on the ionosphere. However, influences of lower atmosphericgravity waves on the ionospheric variability are still not clear due to the simplified gravity wave parameterizations in general circulation models (GCMs) and the limited knowledge of gravity wave distributions. In this study, we aim to study the longitudinalvariations of gravity waves and their impacts on the ionospheric variability.
Variations of lower atmospheric gravity waves are characterized using SABER temperature observations from 2002 to 2012
and also the physically based gravity wave parameterization in the Specified-Dynamics Whole Atmosphere Community Climate
Model (SD-WACCM). Longitudinal variations of gravity waves from SABER and WACCM show the largest variability in JuneAugust at low latitudes. We have implemented these low-latitude gravity wave variations into the thermosphere-ionospheremesosphere-electrodynamics general circulation model (TIME-GCM) to study the responses of the ionosphere. TIME-GCM
shows that wavenumber 3-4 components of TEC variations in June-August are increased by ˜10-15% with the longitudinal variations of gravity waves but there are no significant changes in other months. Potential mechanisms of TEC responses to gravity
wave variations will be discussed.
Keywords: Gravity Wave, Ionosphere, Tides

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PEM06-15

Room:A01

Time:May 27 12:00-12:15

Relationship between phase variation of LF signals and GPS-TEC variations related with
MSTIDs at mid-low latitudes
OHYA, Hiroyo1∗ ; NISHIOKA, Michi2 ; SHIOKAWA, Kazuo3 ; TSUCHIYA, Fuminori4
1

Graduate School of Engineering, Chiba University, 2 National Institute of Information and Communications Technology, 3 SolarTerrestrial Environment Laboratory, Nagoya University, 4 Planetary Plasma and Atmospheric Research Cemter, Graduate Schoolof Science, Tohoku University
It is known that phase of LF transmitter signals largely varies in nighttime rather than in daytime, because uniform solar
ionization in daytime makes the D-region ionosphere smoother. However, the cause of the nighttime phase variations has notbeen revealed. In this study, we focus on the periods of the phase variations of the nighttime LF transmitter signals observed inJapan and South-east Asia. As for Japanese data, we investigated the periods of LF signals observed in 16 April, and 6 May, 2007
by wavelet analysis. The propagation path (40 kHz) of the LF signals was located at Fukushima to Kagoshima. Both on 16 April
and 6 May, 2007, phase variations with a period of about 50 minute was seen at around 11:00 UT and 15:00 UT, respectively.
An occurrence of medium-scale traveling ionospheric disturbances (MSTIDs) was confirmed at 15:00 UT on 6 May, 2007 fromGPS Total Electron Content (TEC) data, while the MSTIDs did not occur on 16 April, 2007. In the presentation, we will discuss
the periods of LF phase variations and GPS-TEC variations in more detail.

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PEM06-16

Room:A01

Time:May 27 12:15-12:30

First simultaneous observation of Ca+ densities in the E region and MSTIDs in the F region
EJIRI, Mitsumu K.1∗ ; TSUDA, Takuo2 ; NISHIYAMA, Takanori1 ; ABO, Makoto3 ; NISHIOKA, Michi4 ;MARUYAMA, Takashi4 ; SAITO, Akinori5 ; NAKAMURA, Takuji1
1

National Institute of Polar Research, 2 The University of Electro-Communications, 3 Graduate School of System Design, Tokyo
Metropolitan University, 4 National Institute of Information and Communications Technology, 5 Department of Geophysics, Graduate School of Science, Kyoto University
In the mesosphere and lower thermosphere region, there are permanent layers of metal atoms and ions, the source of which
is vaporization of cosmic dust and meteoroids during their entry into the Earth’s atmosphere. Some metal atom layers e.g. Na,
K, Ca, and Fe layers, and only Ca+ (Calcium ion) can be observed by ground-based resonance scattering lidars. The National
Institute of Polar Research (NIPR) is developing a new resonance scattering lidar system with a frequency-tunable laser. The
lidar transmitter is based on injection-seeded, pulsed alexandrite laser for 768-788 nm and a second-harmonic generation (SHG)
unit for 384-394 nm. The new lidar is able to measure density variations of minor constituents including Ca+ (393.477 nm). As
a part of the development, observation tests are carried out at NIPR (35.7N, 139.4E) since 2013, and we got the first light fromCa+ layer on 21 August, 2014. The Ca+ density profiles were obtained for ∼5 hours (23:13 LT-28:28 LT) with temporal andheight resolutions of 1 min and 15 m, respectively. During the night, high density and narrow Ca+ layer was observed. The
layer descended from ∼107 km to 99 km with quasi-periodic density perturbations until ∼17 UT and then stayed at around 99
km until sunrise. At the same night, sporadic E (Es ) layer was observed with an ionosonde at Kokubunji by National Instituteof Information and Communications Technology (NICT) (35.7N, 139.5E), also medium scale traveling ionospheric disturbances(MSTIDs) were observed with the dense GPS receiver network (GEONET). In this presentation, we compare these data in detailand discuss relationships between observed Ca+ density perturbations, Es layer and MSTIDs
Keywords: resonance scattering lidar, Ca+, medium scale traveling ionospheric disturbances, GPS-TEC, sporadic E layer

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PEM06-17

Room:A01

Time:May 27 12:30-12:45

Excitation of large-scale gravity waves in the upper thermosphere by interplanetary fluctuations
GUO, Jianpeng1∗ ; LIU, Huixin2
1National Space Science Center, Chinese Academy of Sciences, 2 Earth and Planetary Science Division, Kyushu University

Fluctuations on timescales of minutes to hours are common in the solar wind. When the fluctuations encounter the Earth, they
could induce impulsive auroral intensification, which, in turn, excite gravity waves in the auroral regions. These gravity waves,particularly large-scale (>˜1000 km) gravity waves, will give rise to traveling atmospheric disturbances with typical amplitudes
of 20˜40% in the upper thermosphere. We report here the detection of full constructive interference between two large-scale
gravity waves excited in northern and southern auroral regions by an interplanetary shock, and the detection of extremely efficient multiple excitation of large-scale gravity waves by a long-duration Alfven wave train carried by a high-speed stream.
Keywords: interplanetary fluctuations, gravity wave, traveling atmospheric disturbances, thermosphere

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PEM06-18

Room:A01

Time:May 27 14:15-14:45

Quasi-two day wave related variability in the background dynamics and composition of
the MTI system
CHANG, Loren1∗ ; YUE, Jia2 ; WANG, Wenbin3 ; WU, Qian3 ; MEIER, R.r.4
1

Institute of Space Science, National Central University, Jhongli, Taoyuan County, Taiwan, 2 Center for Atmospheric Science,
Hampton University, Virginia, USA, 3 High Altitude Observatory, National Center for Atmospheric Research, Boulder, Colorado,
USA, 4 School of Physics, Astronomy, and Computational Sciences, George Mason University, Virginia, USA
Dissipating planetary waves in the mesosphere and lower thermosphere (MLT) region may cause changes in the background
dynamics of that region, subsequently driving variability throughout the broader thermosphere / ionosphere system via mixing
due to the induced circulation changes. We report the results of case studies examining the possibility of such coupling during thenorthern winter in the context of the quasi-two day wave (QTDW) - a planetary wave that recurrently grows to large amplitudes
from the summer MLT during the post-solstice period. Six distinct QTDW events between 2003 and 2011 are identified in the
MLT using SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) temperature observations. Concurrent
changes to the background zonal winds, zonal mean column O/N2 density ratio, and ionospheric total electron content (TEC)
are examined using datasets from TIDI (TIMED Doppler Interferometer), GUVI (Global Ultraviolet Imager), and GIMs (Global
Ionospheric Maps), respectively. We find that in the 5 - 10 days following a QTDW event, the background zonal winds in the
MLT show patterns of eastward and westward anomalies in the low and mid-latitudes consistent with past modeling studies on
QTDW-induced mean wind forcing, both below and at turbopause altitudes. This is accompanied by potentially related decreases
in zonal mean thermospheric column O/N2, as well as to low latitude TECs. The recurrent nature of the above changes during thesix QTDW events examined point to an avenue for vertical coupling via background dynamics and chemistry of the thermosphere/ ionosphere not previously observed.
Keywords: quasi-two day wave, ionosphere, thermosphere, mesosphere, composition, dynamics

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PEM06-19

Room:A01

Time:May 27 14:45-15:00

Simultaneous observation of planetary waves in the mesosphere and ionosphere
ESPY, Patrick1∗ ; STRAY, Nora2 ; HIBBINS, Robert1
1

NTNU, Trondheim and Birkeland Centre for Space Science, Bergen, Norway, 2 Norwegian University of Science and Technology (NTNU), Trondheim, Norway
How variations of the neutral atmosphere, in particular planetary wave activity in the mesosphere-lower thermosphere (MLT),
drive variations in the ionosphere has been the subject of recent attention. A method has been developed to observe planetary
wave activity in the northern hemisphere (50-66 ⁰ N) MLT using neutral atmosphere winds derived from meteor trail drifts observed by a longitudinal chain of Super Dual Auroral Radar Network (SuperDARN) radars. The method allows for the removalof tidal effects and provides the temporal variation of the wavenumber 1 and 2 amplitudes without the spatial-temporal aliasingpresent in satellite observations. The method has been extended to utilize the critical plasma frequency and virtual height of theionospheric F-layer derived from a longitudinal chain of ionosondes. Details of the method applied to both the meteor radar andionosonde data will be presented, and the amplitudes and temporal variations of the wavenumber 1 and 2 amplitudes in both the
MLT and the F region will be compared.
Keywords: Planetary wave, Mesosphere, Lower Thermosphere, Ionosphere

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PEM06-20

Room:A01

Time:May 27 15:00-15:15

Ground-based mesopause temperatures at high-latitude over Yakutia:Comparison with
SABER measurements
AMMOSOVA, Anastasia1∗ ; AMMOSOV, Petr1 ; GAVRILYEVA, Galina1 ; KOLTOVSKOI, Igor1
1

ShICRA
Ground-based mesopause temperature at high-latitude over Yakutia: Comparison with SABER measurements
Yu. G. Shafer Institute of Cosmophysical Research and Aeronomy
Petr Ammosov; Galina Gavrilyeva; Anastasia Ammosova; Igor Koltovskoi
tenyka@rambler.ru

Rotational temperatures obtained from the O2 Atmospheric (0?1) nightglow band, with an infrared spectrograph at the
Maimaga station (63 N, 129.5 E) for the period September 2002 to March 2013 are presented. Time series includes the yearsof maximum and minimum solar activity. The set of spectrograph data has been used to analyze the seasonal behaviour of themesopause temperatures. Atmospheric temperatures deduced from infrared spectrograph and from satellite observations with theSounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on board the TIMED satellite, havealso been compared.
The temperatures measured during the satellite passes at distances not larger than 300 km from the intersection of the spectrograph sighting line with the oxygen emitting layer (˜94 km) have been compared. A seasonal dependence is observed regarding
the difference between the ground based and satellite measurements. However, the time variations in the temperature obtainedwith the ground based device and on the satellite are similar. Based on the performed analysis, it has been concluded that a seriesof oxygen rotational temperatures can be used to study temperature variations on different time scales, including long-term trends
at the temperature emission altitude (˜94 km).

Keywords: mesopause temperature, O2 airglow, SABER measurements

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PEM06-21

Room:A01

Time:May 27 15:15-15:30

All-sky measurements of short period waves nightglow emissions
KOLTOVSKOI, Igor1∗ ; AMMOSOV, Petr1 ; GAVRILYEVA, Galina1 ; AMMOSOVA, Anastasia1
1

Yu.G. Shafer Institute of Cosmophysical Research and Aeronomy

Will present the results of statistical analysis of the parameters of internal gravity waves registered on the variations of emission hydroxyl molecule. Wave patterns registered infrared all-sky camera installed on the optical station Maimaga (Yakutia).
Analyzed data received during the winter period 2008-2013. 118 waves were registered, most of which propagated in a westerly direction. For the wave length range from 15 - 70 km (average value is - 29km) observed horizontal phase velocity varies
from 17 to 140.8 m / s (average is -57m / s) and the estimated periods are within 7-40 min (the average is - 9min). Statisticalcharacteristics of the waves do not differ from the results of the registration of such waves at middle and low latitudes. The
azimuthal distribution of the direction of wave propagation is consistent with the theory of filtering background wind waves in
the middle atmosphere. Probable sources of waves are assumed to mountain ranges, located 200 km to the east of the place ofobservation. There are a few large values of the average wavelength and wave propagation velocity than those registered at lower
latitudes. Apparently, this is due to lower energy loss and wave velocity in passing from the source to the mesosphere, although
not excluded for other reasons.
It is planned to identify all-sky measurements of short period waves in the green emission recording OI (557,7 nm) in thevisible wavelength of the spectrum (the height of the airglow ˜96 km). Will present the results of observations at two different
heights (˜87 and 97 km).
Keywords: internal gravity waves, mesosphere, hydroxyl

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PEM06-22

Room:A01

Time:May 27 15:30-15:45

Thermospheric neutral wind profile in daytime and moonlit midnight by Lithium release
experiments
YAMAMOTO, Masa-yuki1∗ ; KIHARA, Daiki1 ; KAKINAMI, Yoshihiro1 ; WATANABE, Shigeto2 ; LARSEN, Miguel3 ;YAMAMOTO, Mamoru4 ; HABU, Hiroto5 ; ABE, Takumi5 ; PFAFF, Robert6
1
6

Kochi University of Technology, 2 Hokkaido Information University, 3 Clemson University, 4 RISH, Kyoto University, 5 ISAS/JAXA,
NASA/Goddard Space Flight Center

Neutral wind profiles were observed in lower thermosphere at about between 90 km and 130 km altitude by using resonancescattering light of sunlit and moonlit Lithium (Li) vapor released from sounding rockets in daytime and midnight (almost fullmoon condition) in 2013. As a target of the Daytime Dynamo campaign, Li release experiment was operated at Wallops Flight
Facility (WFF) of NASA, U.S.A. in July, 2013, while the same kind of experiment in midnight was carried out in Uchinoura
Space Center (USC) of JAXA, Japan also in July 2013. Since imaging signal-to-noise (S/N) condition of the both experiments
was so severe, we conducted to apply airborne observation for Li tracers imaging so as to reduce the illuminating intensity ofbackground skies as an order of magnitude.
Two independent methods for calculating the wind profile were applied to the image sequences obtained by the airborne imaging by special Li imagers aboard the airplanes in order to derive precise information of Li tracers motion under the conditionof single observation site moving along the aircraft path in the lower stratosphere. Slight feedback motion of the aircraft 3-axes
attitude changes (rolling, yawing and pitching) was considered for obtaining precise coordinates on each snapshot. Anotherapproach is giving a simple mathematic function for wind profile to resolve the shape displacement of the imaged Li tracers. As
a result, a wind profile in daytime thermosphere was calculated in a range between 20 and 95 m/s with some fluctuated parts
possibly disturbed by wind shears. In this paper, we will introduce the method of wind profile calculation and final result of the
profiles.
Keywords: Thermosphere, Neutral wind profile, Lithium release, Airborne observation, Method, Sounding rocket

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PEM06-23

Room:A01

Time:May 27 15:45-16:00

Atmospheric dynamics InfraStructure in Europe: The ARISE project
BLANC, Elisabeth1 ; KERO, Johan11∗ ; CERANNNA, Lars2 ; HAUCHECORNE, Alain3 ; CHARLTON-PEREZ, Andrew4 ;KVAERNA, Tormod5 ; RIPEPE, Maurizio6 ; RAPP, Markus7 ; EVERS, Laslo8 ; LUEBKEN, Franz-jozef9 ;BLINDHEIM, Sandra10 ; ESPY, Patrick12 ; LASTOVICKA, Jan13 ; BOSSU, Remy14 ; CAMMAS, Jean-pierre15 ;KAEMPFER, Niklaus16 ; PRICE, Colin17 ; MULLIGAN, Frank18 ; VOGFJORD, Kristin19 ;RAMBOLAMANANA, Gerard20 ; IONESCU, Constantin21 ; WALLENSTEIN, Nicolau22 ; AGREBI, Abdelouaheb23 ;DIAWARA, Adama24
1

CEA France, 2 BGR Germany, 3 CNRS France, 4 UREAD United Kingdom, 5 NORSAR Norway, 6 UNIFI Italy, 7 DLR/IPA Germany, 8 KNMI Netherlands, 9 IAP/Kuhlungsborn Germany, 10 ALOMAR Norway, 11 IRF Sweden, 12 NTNU Norway, 13 IAP/Prague
Czech Republic, 14 CEA subcontracting France, 15 Univ Reunion France, 16 IAP/Bern Switzerland, 17 TAU Israel, 18 NUIM Ireland, 19 IMO Island, 20 IOGA Madagascar, 21 NIEP Romania, 22 FGF Portugal, 23 CNCT Tunisia, 24 LAMTO Ivory Coast
There is currently a lack of observations, data and model parameters, which are needed in weather and climate models. ARISE
is an EU-funded infrastructure project (FP7 2012-2014 and H2020 2015-2018) with a long-term objective to fill this gap andsolve persistent problems facing the applications which depend on atmospheric dynamics. The atmosphere is a dynamic medium
being continuously disturbed by winds and atmospheric waves over a broad range of time and spatial scales. Disturbances include
large-scale waves such as gravity and planetary waves which transfer energy and momentum from one region of the atmosphereto another. Atmospheric extreme events such as volcanoes, stratospheric warming events, magnetic storms, tornadoes and tropical thunderstorms also constitute significant disturbances to atmospheric dynamics.
The ARISE project aims at establishing a unique atmospheric research and data platform in Europe and outlying regions,
including the polar and equatorial regions. It will combine observations with theoretical and modelling studies to elucidate thedynamics of the middle and upper atmosphere. For the first time, several technologies (infrasound, lidar, airglow, radars, ionospheric observations and satellites) will be used simultaneously and in a complementary way. The measurements will be used to
improve the parameterization of gravity waves in the stratosphere to better resolve climate models. Such description is crucial
to estimate the impact of stratospheric climate forcing on the troposphere. The collected data are required to improve weather
forecasting to monthly or seasonal scales, remote volcano monitoring, climate monitoring and other applications. The ARISE
data portal aims to provide high-quality, easy-to-use data and advanced data products to a wide scientific community.
Keywords: atmospheric dynamics, infrasound, gravity waves, planetary waves, weather forecasting, climate monitoring

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PEM06-P01

Room:Convention Hall

Time:May 26 18:15-19:30

Observation of Ozone concentration relation to meteors echo duration distributions by aforward scattering radar
MADKOUR, Waleed1∗ ; YAMAMOTO, Masa-yuki1 ; MIZUMOTO, Satoshi11

Kochi University of Tech.

Several studies have concluded the existence of secondary maxima of ozone concentration at the mesospheric level of 8590 km. At this level in atmosphere, meteor radio observations shows a consistent lack of long overdense echoes with certain
durations where the number of meteor echoes drops for what is known as the ‘knee’ position. As the lack of long meteor echoes
was significantly greater than being only a result of ambipolar diffusion, some studies linked this drop to ozone concentrationin the meteor region. Baggley and Cummack (1974) suggested the drop to be the result of oxidation of meteors ions by thesecondary maxima of ozone layer which causes the removal of ionization and consequently unreflected radio signals. Joneset. al (1990) and Cevolani and Pupillo (2003) supported this conclusion by analyzing meteor echoes duration distributions anddetermining approximately the height of meteor echoes at the knee point based on visual magnitude levels.
At Kochi University of Technology (KUT) we attempted to observe the knee position in selected meteor showers. The 5
channel HRO interferometer radar developed at KUT utilizes forward scattering of 53.75 MHz continuous radio signals emitted
from Sabae station, Fukui prefecture, Japan (Fukui National College of Technology: FNCT) at a distance of 340 km from
Kochi prefecture. The software HROFFT (Ham-band Radio meteor Observation Fast Fourier Transform) generates spectrogram
images for meteor echoes in 10 minute intervals. These images are used by the developed auto counting software Meteor echo
counter through image processing to automatically count meteor echoes and their durations. The critical duration T at which
the drop occurs in long echoes counts can be indicative about the Ozone concentration by the relation derived by McIntosh andHajduk (1977): O 3=(αT)ˆ(-1). As currently there is no developed mechanism for meteor height determination at KUT, thescope is focused on the analysis of meteor echoes duration, detection of the knee point and then finally comparing the ozone
concentration measurements to the results of similar studies.
References:
BAGGALEY, W.J. and CUMMACK, C.H., (1974): Meteor train ion chemistry. J. Atmos. Terr. Phys. 36, 1759
CEVOLANI, G and PUPILLO, G (2003): Ground-based radio observations to probe the ozone content in the meteor region,
Annals of Geophysics, 46. 247-258
JONES, J.MCINTOSH, B.A & SIMEK, M. (1990): Ozone and the duration of overdense radio meteors. J. atmos. terr. Phys.
52, 253.
MCINTOSH, B.A. and A.HAJDUK (1977): Sunrise effect on persistent radar echoes from sporadic meteors, Bull. Astron.
Inst.Czechosl., 28, 280-285.
Keywords: Ozone concentration, meteors, forward scattering, radar, mesosphere

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PEM06-P02

Room:Convention Hall

Time:May 26 18:15-19:30

Simultaneous observations of polar mesosphere winter echoes (PMWE) and Cosmic Noise
Absorption (CNA) by the PANSY radar
NISHIYAMA, Takanori1∗ ; SATO, Kaoru2 ; NAKAMURA, Takuji1 ; TSUTSUMI, Masaki1 ; SATO, Toru3 ;KOHMA, Masashi2 ; NISHIMURA, Koji1 ; TOMIKAWA, Yoshihiro1 ; EJIRI, Mitsumu K.1 ; TSUDA, Takuo4
1

National Institute of Polar Research, 2 Department of Earth and Planetary Science, The University of Tokyo, 3 Department ofCommunications and Computer Engineering, Kyoto University, 4 Department of Communication Engineering and Informatics,
University of Electro-Communications
In the lower thermosphere at the altitude of around 100 km, both neutral turbulence and ionization of atmosphere due to solar
radiations cause irregularities of refractive index, and as a result back scatter echoes from that altitude are frequently observedby radars on the ground. In the mesosphere, Polar Mesosphere Summer Echo (PMSE) is reported to be a strong echo associatedwith ice particles, which are produced around the coldest mesopause region in the polar summer, by a number of past radarobservations [Cho and Röttger, 1997; Rapp and Luebken, 2004]. It should be also noted that occurrence rate of PMSE is very
high (80-90%) [Bremer et al., 2003]. On the other hand, Polar Mesosphere Winter Echo (PMWE) is also known as back scatterecho from 55 to 85 km in the mesosphere, and it has been observed by MST and IS radar in polar region during winter [e.g.,
Ecklund and Balsley, 1981; Czechowsky et al., 1989; Luebken et al., 2006; Strelnikova and Rapp, 2013]. Due to the lack of offree electrons and ice particles in the dark and warm mesosphere during winter, it is suggested that PMWE requires strong ionization of neutral atmosphere associated with precipitations of Solar Energetic Particles (SEPs) during geomagnetically disturbed
periods [Kirkwood et al., 2002; Zeller et al., 2006]. However, the detailed generation process of PMWE has not been identified
yet, partly because the reported PMWE occurrence rate was quite low (2.9%) [Zeller et al., 2006].
We present occurrence characteristics of PMWE from June 2012 to October 2013 and its relation to Solar Energetic Particles.
When PMWE was detected by the PANSY (Program of the Antarctic Syowa MST/IS) radar, highly energetic particle precipitations, either protons or electrons, were frequently observed by NOAA satellite particle measurements above Syowa Station.
During the SPE that occurred in May 23, 2013 PMWE and a significant Cosmic Noise Absorption (CNA) of about 1 dB were
simultaneously detected by the PANSY radar. MF radar also showed Isolated Lower Mesosphere Echo (ILME) at the same time[Morris et al., 2011], suggesting enhancement of electron density in ionospheric D-regions. Moreover, occurrence of PMWE was
likely related to the flux of precipitating electrons in the medium energy range (30-300 keV) during recovery phase of geomagnetic storms. We would like to show correlations between PMWE and CNA using dataset for mesospheric observation mode.
Keywords: Polar Mesoshpere Winter Echo, Eneregetic Particle Precipitation, Ionospheric D-region, Trubulence, Cosmic Noise
Absorption, the PANSY radar

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PEM06-P03

Room:Convention Hall

Time:May 26 18:15-19:30

Gravity wave activity in a wide height range of 65-110km over Syowa st. (69S), Antarctica
TSUTSUMI, Masaki1∗
1

National Institute of Polar Research

There are very small number of ground-based observation techniques in the lower thermosphere, especially above around 100
km, although the region is a pronounced transition region in terms of the thermal structure, chemistry and dynamics. Radio
meteor echo measurement in a low radio frequency such as MF is a possibility of atmosphere observation above 100 km. We
have applied a meteor wind measurement technique, which is widely used in VHF, to MF radar systems, and have successfully
obtained meteor winds up to 120 km altitude [Tsutsumi et al, 1999; Tsutsumi and Aso, 2005]. The technique was applied to the
MF radar at Syowa station, Antarctica and meteor winds have been continuously obtained since May 1999, simultaneously withconventional correlation based wind measurements in the mesosphere.
In this study we try to estimate seasonal behavior of gravity wave activity over Syowa in a wide height range from 65 to 110km
using the accumulated 16 years of data. Gravity wave activity is estimated in two ways. One is a commonly used wave varianceestimation technique based on time series of wind velocities [e.g., Vincent, 1994]. Hourly mean winds are used for the purposein the present study. The other is a recently developed technique by Mitchel and Beldon [2009], where residuals after the hourlymean wind estimation are used as a proxy of short period wave activity. The former and the latter correspond to wave periods
longer and shorter than about two hours, respectively. Obtained wave activities show a broad winter time maximum and summer
time minimum in both wave periods, which is consistent with previous results in the mesosphere over Antarctica [Dowdy etal.,2007]. We further found that wave activities above 100 km are enhanced in late summer to early winter in both wave periods,
which has not been known so far. Details of these features are discussed in the presentation.
Keywords: atmospheric gravity waves, mesosphere and lower thermosphere, Antarctica, MF radar, Syowa station

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PEM06-P04

Room:Convention Hall

Time:May 26 18:15-19:30

Variability of the Equatorial Ionization Anomaly on seasonal and day to day time scales
CHIEN, Shin han1∗ ; CHANG, Loren1 ; LIU, Huixin2
1

Institute of Space Science, National Central University, Jhongli City, Taiwan, 2 Earth and Planetary Science Division, Kyushu
University SERC, Kyushu University
The Equatorial Ionization Anomaly (EIA) is a persistent feature of the F layer, around 300 km altitude in the thermosphere,
generated by the E-region dynamo driven equatorial fountain. When the EIA is present, electron densities on either side of themagnetic equator will become much higher during the local afternoon times. In our study we want to quantify short term EIA
variability due to atmospheric, solar, and geophysical sources. Short-term anomalies in EIA region total electron content (TEC)from GPS-derived global ionosphere maps (GIM) at 105 degree West longitude are compared to anomalies in three different
geophysical sources: solar flux (F10.7 solar flux proxy), geomagnetic storms (Kp index), and atmospheric zonal winds near
the semidiurnal tidal peak at northern mid-latitudes (GAIA assimilative general circulation model). We present spectral andcoherence analysis of EIA TECs and the aforementioned geophysical indices in 2008 and 2012, to illustrate the variability on
seasonal and day to day time scales. The variability of the F10.7 solar flux proxy is dominated by 23-27 day periodicities. The Kp
index indicates significant 9 day periodicities in 2008 for entire year, though 2012 is dominated by significant variations with 913 day periods during equinox and 5-7 day periods during boreal summer. F10.7 and Kp index both demonstrate good coherencewith EIA TECs during specific seasons. With regard to the neutral zonal winds, TECs at the equator show good coherence with100 km mid-latitude zonal winds in the same longitude region at specific planetary wave periods during the certain local times,suggesting modulation of the E-region dynamo.
Keywords: Equatorial Ionization Anomaly, ionosphere, mid-latitude, planetary wave, Kp index, E-region dynamo

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PEM06-P05

Room:Convention Hall

Time:May 26 18:15-19:30

Topside Ionospheric Plasma Temperatures Retrieved From FORMOSAT-3/COSMIC Observations
WANG, Jack C.1∗ ; CHANG, Loren C.1 ; LIU, Jann-yenq1
1Graduate Institute of Space Science, National Central University, Taiwan

Bottom-side ionospheric electron profiles now can be well-determined thanks to mature development of ground-based instruments, such as ionosonde, or incoherent radar. However, the topside ionosphere, located above the F2 layer peak to the exobase(from 200˜400 km to 600˜1000km, depending on solar activity) is still not well understood. Previously, the electron density distribution and plasma temperatures in the topside ionosphere could only be measured by incoherent scatter radar, in-situ sounding
rocket, or certain satellite instruments, making it hard to draw a global map of electron density and plasma temperatures in thetopside ionosphere. FORMOSAT-3/ Constellation Observing System for Meteorology, Ionosphere, and Climate (F3/C) using the
GPS radio occultation method (GPS-RO) now can give us great opportunities to determine the global electron density profiles
above the F2 layer peak. We also present results showing how the plasma temperatures may be estimated from such GPS-RO
observations.
This study first examines the structure and variability of electron densities in topside ionosphere. Seasonal F3/C observations
will first be assimilated into a gridded model in latitude, longitude, altitude, and local time. The resulting vertical profiles at
each gridpoint will then be used to infer the vertical scale height of the topside ionosphere. Next, we retrieved the seasonal andlocal-time variabilities of topside plasma temperature from the scale height of topside ionospheric electron densities. This is oneof the first times that topside plasma temperatures can be globally determined using remote sensing techniques.
Keywords: Ionosphere, Topside ionosphere, Plasma temperature, Formosa-3/COSMIC

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PEM06-P06

Room:Convention Hall

Time:May 26 18:15-19:30

Development of real-time three-dimensional GPS-TEC tomography
SUZUKI, Shota1∗ ; YAMAMOTO, Mamoru1 ; CHEN, Chieh-hung4 ; SAITO, Susumu2 ; SEEMALA, Gopi1 ;SAITO, Akinori3
1

Research Institute for Sustainable Humanosphere, Kyoto University, 2 Department of Geophysics, Graduate School of Science,
Kyoto University, 3 Navigation Systems Department, Electronic Navigation Research Institute, 4 Department of Earth and Environmental Sciences, National Chung Cheng University, Taiwan
Recently, a new three-dimensional GPS ionospheric tomography technique is developed which uses total electron content(TEC) data from the dense GPS receiver network, GPS Earth Observation Network (GEONET) in Japan. It uses the least squares
fitting method constrained by the spatial gradient, and does not require an ionospheric model as the initial guess that could bias
the reconstruction of electron density. But it refers to the NeQuick model to determine constrained parameters. The purposeof this study is to develop this technique and incorporate into the real-time GPS-TEC monitoring system. First we increase thecomputation speed by using a sparse matrix algorithm when solving the least squares fitting method. Programmed with Python,it takes less than 5 minutes to calculate a tomography by using 1.7GHz Intel Core i7. We could also improve the stability of thecalculation. Furthermore we try to find a new method for determining the constrained parameters by analyzing a large amountdata. As the tomography uses absolute TEC, it is necessarily to estimate instrumental delay bias which is originated in the hardware of the GPS satellite and receiver. We develop the bias estimation procedure that uses RINEX-OBS data of the previous day.
Organizing these parts, we develop a system to conduct three-dimensional tomography analysis in the real-time basis.
Keywords: GEONET, TEC, tomography, sparse matrix, real-time system

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PEM06-P07

Room:Convention Hall

Time:May 26 18:15-19:30

Performance evaluation of low-cost airglow camera for mesospheric gravity wave measurements
SUZUKI, Shin1∗ ; SHIOKAWA, Kazuo1
1

Solar-Terrestrial Environment Laboratory, Nagoya University

Atmospheric gravity waves significantly contribute to the wind/thermal balances in the mesosphere and lower thermosphere(MLT) through their vertical transport of horizontal momentum. It has been reported that the gravity wave momentum flux
preferentially associated with the scale of the waves; the momentum fluxes of the waves with a horizontal scale of 10-100 km
are particularly significant. Airglow imaging is a useful technique to observe two-dimensional structure of small-scale (<100km) gravity waves in the MLT region and has been used to investigate global behavior of the waves. Recent studies with simultaneous/multiple airglow cameras have derived spatial extent of the MLT waves. Such network imaging observations areadvantageous to ever better understanding of coupling between the lower and upper atmosphere via gravity waves.
In this study, we newly developed a low-cost airglow camera to enlarge the airglow imaging network (Optical Mesosphere andThermosphere Imagers: OMTIs) operated by the Solar-Terrestrial Environment Laboratory, Nagoya University. This camera has
a fish-eye lens with a 185-deg field-of-view and equipped with a CCD video camera (WATEC WAT-910HX) ; the camera is small(W35.5 x H36.0 x D63.5 mm) and inexpensive, much more than the OMTI cameras, but has a highly sensitive CCD sensor with
768 x 494 pixels. OH airglow emissions are imaged at intervals of 4 sec with 4-sec exposure.
In this presentation, we will report some results of performance evaluation of this camera based on test observations at Shigaraki (35-deg N, 136-deg E), Japan, where is one of the OMTI station. By summing 15-images (i.e., 1-min composition of theimages) we recognized clear gravity wave patterns in the images with comparable quality to the OMTI’s image.

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PEM06-P08

Room:Convention Hall

Time:May 26 18:15-19:30

The FORMOSAT-3/COSMIC Radio Occultation Data Assimilated to NCAR/TIE-GCM
to study the horizontal winds in the ionosphere
CHEN, Ming-quey1∗ ; SU, Yung-chih1 ; CHAO, Shih-hao1
1

Grad. Inst. of Space Science, National Central Univ., Taiwan

The NCAR Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIE-GCM) is a self-consistently electrodynamiccoupled thermosphere and ionosphere model subjected by a few parameters and boundary conditions. The migrating tidal
waves are parameterized with the amplitudes and phases of the diurnal and semidiurnal tidal waves (Hough modes) as the forcing sources to modulate the TIE-GCM at the lower boundary. We constructed a data assimilation method to assimilate the
FORMOSAT-3/COSMIC (F3/C) occultation total electron content (OTEC) observations to the Model with the optimal parameters of the TIE-GCM. The assimilated OTEC of the F3/C data could modulate the ionospheric electron densities, the neutral
winds and the temperatures in the TIE-GCM due to the optimal parameters of the Hough modes. The horizontal wind in theassimilated model will be compared with the observations with ground based and the space-borne instruments (TIDI data).
Keywords: ionosphere, thermosphere, FORMOSAT-3/COSMIC radio occultation data, data assmilation

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PEM06-P09

Room:Convention Hall

Time:May 26 18:15-19:30

Periodic variations in the thermospheric density
LIU, Huixin1∗ ; TSUBOSAKI, Hiroyuki1
1

Kyushu University, Japan

We examined the periodic variation of thermosphere in this study using the thermospheric total mass density at 400km altitude
derived from more than 5000 flying objects during 1967-2013, and also those measured by the accelerometer aboard the CHAMP
satellite during 2001-2010. Among the periodic variations, we found a prominent 2-3 year period. Correlation of this density
variation with QBO and ENSO indices are carried out to investigate possible lower atmosphere driver of this thermospherevariability.
Keywords: thermosphere

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PEM06-P10

Room:Convention Hall

Time:May 26 18:15-19:30

Evaluation of EEJ variation due to Ultra Fast Kelvin Waves using the Kyushu-GCM andthe Quasi-3D dynamo model
GOYA, Kenshi1∗ ; MIYAHARA, Saburo2 ; CHEN, Ying-wen3
1

Dept. of Earth and Planetary Sci., Kyushu University, 2 Kyushu University, 3 JAMSTEC

The quasi-3dimensional dynamo-model using the neutral wind data of the Kyushu-GCM(Yoshikawa and Miyahara 2003,
2005) proves that Sq current system and Equatorial Electro Jet (EEJ) can be almost consistent with their day to day variations of
the observation values (Kawano-Sasaki and Miyahara 2008, Aramaki 2012:Master Degree thesis).
And then analysis of Kelvin Waves in the Kyushu-GCM (Chen and Miyahara 2012) shows that Ultra Fast Kelvin (UFK) waves(zonal wavenumber =1, Period 2.5-4 days) originated in the troposphere are dominant in the MLT region above the equator (ataround 100 km height) and contribute to the dynamical field of atmosphere. And the amplitudes of UFK waves fluctuate periodically at almost 10 days time scale.
Therefore this research shows that the contribution to EEJ variation due to UFK wind fluctuation has been quantitatively evaluated using the quasi-3dimensional dynamo-model that can express Sq current system and EEJ in asymmetric about the equator(Aramaki 2012 : Master Degree thesis) with UFK neutral wind data derived from the Kyushu-GCM (Yoshikawa and Miyahara
2003, 2005). This evaluation proves that UFK winds fluctuation contribute to EEJ day to day variation. Particularly it is evaluated that UFK winds day to day fluctuation contributes to about 25 percent of the strong Eastward EEJ current values day to
day variation above around the Equator comparing the standard deviations of the simulated EEJ current values between the caseof the UFK winds data at one month and the case of the Kyushu-GCM original neutral winds data at the same month. Morecomprehensive analysis and its evaluations in detail will be shown at the conference hall.
(Acknowledgement)
The Quasi-3D Dynamo equatorially symmetric model (2008) that Dr.Keiko Kawano-Sasaki (Kyushu University) had developed and M.Sc. Yui Aramaki (Kyushu University) had extended it to the asymmetric model (2012). We used the model for thisresearch. We gratefully acknowledge for them.

Keywords: Equatorial Electro Jet, Ultra Fast Kelvin wave, the Kyushu-GCM, the quasi-3D dynamo model

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PEM06-P11

Room:Convention Hall

Time:May 26 18:15-19:30

The relationship between the electric field in the lower atmosphere and Sq variations
IKEDA, Akihiro1∗ ; CARDINAL, G. maria2
1

Kagoshima National College of Technology, 2 International Center for Space Weather Science and Education

The vertical atmospheric electric field (Ez) variations depend on the state of the global electric circuit. Geomagnetic phenomena can influence Ez through ionospheric disturbances [e.g. Kleimenova, 2008]. The daily quiet geomagnetic field variations (Sqvariations) are mainly caused by electric field currents flowing in the E region of the ionosphere. It is likely that Sq variations
are relevant to Ez variations. In this study, we aim to investigate the relationship between Ez and Sq variations at a low-latitude
station. We analyzed the Ez and ground magnetic field data (H) at KAK (G.G. Lat.: 36.2 N, G.G. Lon.: 140.2 E) station during
2006 - 2014. The data was provided by the Kakioka Magnetic Observatory of the Japan Meteorological Agency. In here, we
adopt the same definition for Sq amplitudes as defined by Yamazaki et al. [2010]. The daily amplitude of the Sq variation isderived by subtracting nighttime (22-24 LT and 00-02 LT) H values from daytime H (peak) values. Similarly, we calculated thedaily Ez variation. The daytime Ez values were selected at the time when daytime H values show their peaks. The obtained
Sq and Ez variations show annual and semi-annual variations. The annual variations are clearly seen every year, becoming thesmaller values in winter. The semi-annual variations in Ez are clear in 2011 and 2014. As just described, we found similarities
between Sq and Ez variations in several respects and ,therefore, conclude that the Ez variations depend on the condition of theionosphere.
Keywords: atomospheric electric field, Sq

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