COMMISSION F：Wave Propagation and Remote Sensing (November 2013
－October 2016)
Edited by Yasuyuki Maekawa

Contents: F1 Wave Propagation
F1.1 Terrestrial Fixed Radio System
A. Effects of Atmosphere
B. Effects of Vegetation
C. Others
F1.2 Satellite Radio System
A. Effects of Rain
B. Effects of Other Factors
F1.3 Mobile Radio Systems
A. Propagation for Cellular Systems
B. Channel Estimation and Channel Sounding Method
C. Formulations of Mobile Propagation
D. Machine-to-Machine/Infrastructure Propagation
E. Indoor/Outdoor-to-Indoor Propagation
F. Blocking Effect of Human Bodies
G. Millimeter-wave, THz and Optical Propagation
H. Others
F2 Remote Sensing
F2.1 Atmosphere
A. Ground-based Remote Sensing Studies
B. Space-based Remote Sensing Studies
F2.2 Hydrometeors and Other Particles
A. Ground-based Remote Sensing Studies
B. Space-based Remote Sensing Studies
F2.3 Land
A. Land Surface
B. Subsurface Objects and Landmine Detection
F1. Wave Propagation
F1.1 Terrestrial Fixed Radio System
A. Effects of Atmosphere
An overreach measurement method that simultaneously monitors RSSI and CNR of the TV
waves and RSSI of FM waves is newly proposed. The results of measurements conducted in
Hiroshima prefecture show that our proposed method can evaluate the level of overreachinterference in the TV waves and also identify the source of the interference. Total 43 overreachinterference events were found in the proposed method from one-year measurement in 2012. Basedon M profile data, this paper also shows that the main factor of the overreach interference in thismeasurement is duct propagation due to meteorological condition [Nishi et al., 2014a].
Terrestrial TV waves and FM waves from Korea to Japan were measured to investigate
overreach interference in digital TV waves. In order to evaluate co-channel interference in the TV
waves, we proposed a measurement method that monitored both RSSI and CNR of the digital TV
waves and RSSI of FM broadcasting waves from several cities at the same time. Based on1measurements of TV and FM waves, this study clarified that our proposed method was effective toevaluate the interference from Korea [Nishi et al., 2014b].
In western Japan, UHF band terrestrial digital TV waves have been sometimes affected byco-channel overreach interferences from Korea. To evaluate the co-channel interferences, we havemeasured both RSSI and CNR of the digital TV waves and RSSI of FM broadcasting waves at
Kyushu Institute of Technology in Fukuoka prefecture. In this study, we tried to estimate theoverreach interference sources based on our proposed method monitoring FM waves transmitted
from stations nearby the several candidates of interference sources. From the measurement results, it
was found that the main overreach interference was from Korea, and that the main factor of theinterference was an atmospheric duct propagation occurred over the sea [Nishi et al., 2015].
Also, the terrestrial digital TV waves have possibilities of influences by co-channel overreachinterferences from not only Japan but also Korea. We have been observing the interferences basedon our original measurement method using FM waves for identifying the interference of TV wave.
In this study, we evaluated seasonal characteristics of overreach interferences from Japan and Korea
using our method. It was found that the main overreach interferences were from Korea, not fromJapan [Taniyama et al., 2016].
The human detection system using UHF band TV waves was proposed and evaluated for the
car security. The measurements were performed in the parking space by the human detection systemusing software-defined radio with four receiving antennas. As a result, it was confirmed that humandetections measured by the one receiving antenna were limited to specific areas such as vicinities ofreceiving antennas. In order to improve human detection performances, we evaluated the humandetection using multiple frequencies. As a result, we found that detection probabilities became
higher in almost all areas, and the human detected area was expanded [Shin et al., 2016].

B. Effects of Vegetation
The loss characteristics of radio propagation in 920-MHz band in a farm were investigated. An
experiment was carried out in a mulberry field of the area of 50 m × 50 m in order to obtainfundamental data of the path loss in the field. Received Signal Strength Indicator (RSSI) according
to the distance between the transmitting antenna (Tx) and the receiving antenna (Rx) wasinvestigated. Tx was placed at a height of 1.5 m, and Rx was placed at three different heights of 0.5
m, 1.5 m, and 2.5 m. The polarization was set in two different directions; horizontal and verticalpolarization. These data are needed to precisely calculate a link budget of a wireless network[Tsutsui et al, 2014].
To design a wireless sensor network for farms, it is necessary to understand and predict the effectof vegetation. In this study, the change in the propagation loss characteristics in 920-MHz band is
examined during the growth of mulberry bushes. The received signal strength indicator (RSSI) is
measured as a function of the distance between the transmitting antenna (Tx) and the receiving
antenna (Rx) in a 50×50m mulberry field. The Tx and Rx are placed at a height of 1.5m. Moreover,the horizontal and vertical polarizations are measured and the differences are shown. Three empiricalvegetation attenuation models are introduced, and the measured data have been fitted to each model.
The results show that the non-zero gradient model is the best model at predicting the vegetation
attenuation in a mulberry farm regardless of the polarization or mulberry growth. It is found that theattenuation dependence on the plant height is linear. Furthermore, the results have revealed that thehorizontal polarization had about 1.5 times as large an effect on the vegetation attenuation as thevertical polarization [Hara et al., 2016].
C. Others
In fracturing rock, radio wave emission was found experimentally. This phenomenon could be
used to detect a rock fracture during an earthquake or a volcanic activity. The cause of the radio
wave is expected to be micro-discharges, which are generated by an inhomogeneous potential
distribution around micro-cracks. In order to better understand the phenomena and clarify the2cause of radio wave emission, we carried out experiments to detect the emission in the cases of acollision or contact between various materials [Takano et al., 2014].
It was confirmed that radio waves were generated when metallic parts in the experiment system
collided each other. Therefore, it is absolutely needed to discriminate these signals that were notoriginated by rock fracture itself. Recently, we have remodeled the experiment system, of which all
metallic pars are electrically shorted. Accordingly charging effect of the metallic parts is prevented
in the rock fracture process. This paper describes the constitution of the experimental system andmeasured results [Takano et al., 2015a].
In order to discriminate the real signals generated in the rock fracture process from theinterference signals due to metal collisions in the pressing machine, the conditions of the radio-wave
signal generation should be studied. Therefore, we renewed the pressing machine and carried out
experiments to detect radio-waves for the purpose of the experiment system reexamination. First, weused various lighting instruments, and clarified that the signal generation depends on the discharge
mechanism. Then, various metals were made collide or touch each other. In all cases, the signals
were detected. Resultantly, it has been concluded that inhomogeneous potential distribution whichcauses micro discharges should be suppressed. In the subsequent experiments, we have shorted allparts in the pressing machine using thick wires [Takano et al., 2015b].
There was a concern that the desired microwave emission by rock fracture would becontaminated by the emission originated by the metal contact. Therefore, we improved the machineby connecting and shortening all parts of the machine with wires to keep the homogeneous
distribution of potential. As a result, we demonstrated that the emission due to metal contact wasalmost completely suppressed. This paper presents first the experimental results of radio wave
emission due to metal contact. Then, the modification of the pressing machine, and the experimental
results of radio wave emission due to rock fracture will be described [Takano et al., 2016].
A model for predicting path loss at the VHF band for low antenna heights is presented.
Differences between path loss characteristics at the VHF band and at bands above the UHF band areclarified. The model is shown to be able to predict measurement results accurately [Sasaki et al.,2014a, 2014b].

F1.2 Satellite Radio System
A. Effects of Rain
The indexes of the degradation of C/N, ΔT/T and I/N, which can be converted from one toanother, are used to evaluate the impact of interference on the satellite link. However, it is notsuitable to intuitively understand how these parameters degrade the quality of services. In this paper,
we propose to evaluate the impact of interference on the performance of BSS (Broadcasting Satellite
Services) in terms of the increase rate of the outage time caused by the rain attenuation. Some
calculation results are given for the 12GHz band BSS in Japan [Shogen, et al., 2016].
Speeds and directions of the motion of rain areas that cause the attenuation of Ku-band satellite
communications links are estimated from the broadcast satellite (BS) signal levels simultaneously
obtained at three locations of Osaka Electro-Communication University (OECU; Neyagawa, Osaka),
the Research Institute for Sustainable Humanosphere (RISH; Uji, Kyoto) and the Shigaraki MU
radar observatory (Koga, Shiga) of Kyoto University. The speeds and directions of rain area
motion are compared with the ground wind velocities observed by a nearby AMeDAS station from2008 to 2011. A correlation coefficient of nearly 0.6 is found between the directions of the rain
area motions and the ground wind velocities although the directions tend to be rotated slightly
anti-clockwise on the ground. Thus, the AMeDAS data seems to be important to determine thedirection of satellite stations when the site diversity techniques are conducted [Maekawa et al., 2014,2015].
The speeds and directions of rain area motion estimated from the BS signals at three locations
are also compared with those of rain fronts obtained from image analyses of real time weather charts

3and rain cloud images recently published in the website by Japan Meteorological Agency. The
speeds and directions are in fairly good agreement with those estimated from rain front and rain
cloud Images down loaded from the websites, although the speeds tend to be faster in the BS signal
measurements than in the images of the websites. So, the information on the rain area motions
expected to be useful for site diversity techniques will be easily obtained by the image analysis
methods presented by this study [Kubota et al., 2015, 2016].
The effects of site diversity techniques on Ku-band rain attenuation are investigated using two
sets of simultaneous satellite signal observations, which have been conducted among Osaka
Electro-Communication University (OECU) in Neyagawa, Kyoto University in Uji, and Shigaraki
MU Observatory in Koga for about past nine years, and among the headquarters of OECU in
Neyagawa and their other facilities in Shijonawate and Moriguchi for about past six years. The site
diversity effects are found to be largely affected by the passing direction of rain areas. The
diversity effects primarily depend on the distance between the sites projected to the rain area
motions, and the time percentages of rain attenuation can be reduced down to about 60 % of the
ITU-R predictions between the fixed two sites, by choosing a pair of the two sites out of the three,which is aligned nearest to the rain area motion in each rainfall event [Maekawa et al., 2016b].
The long-term rain attenuation statistics of cumulative time percentages are obtained from Kuband satellite signal observations conducted at Osaka Electro-Communication University in
Neyagawa, Osaka, from 1988 to 2016. The long-term statistics for about 20 years up to 2006 are invery good agreement with the recent ITU-R predictions obtained from the 0.01% rainfall rate, andtheir 0.01% values indicate fairly large yearly variations which amount to about 20% of each value.
Besides the yearly rainfall rate statistics, these variations seem to be caused by those of theequivalent rain path length at each year, which becomes longer as the average ground temperature atrain time from May to October becomes higher. However, the increase of the equivalent rain path
length is not simply explained in term of the rise of rain height proportional to the groundtemperature, but rather related to the occurrence of rain attenuation due to tropical-type rainfall suchas shower and typhoon in summer time. Also, the equivalent path length tends to increase further
for the last 10 years since 2006, and this tendency seems to be related to the overall increase of theaverage ground temperature at rain time in each year. It is actually found that the average groundtemperature at rain time becomes higher by 1-2° primarily in summer time since 2006. New
prediction models which take into account recent climate change and meteorological conditions will
be expected in the near future. [Miura and Maekawa, 2016]
Rain attenuation statistics are obtained for both up and down links of Ku-band Superbird C,
which connects the earth stations at Equatorial Atmosphere Radar (EAR) in West Sumatra,Indonesia and Research Institute of Sustainable Humanosphere (RISH) of Kyoto University in Uji,
Kyoto during four years from Sept. 2002 to Sept. 2006. The rain attenuation characteristics arecompared with distribution of precipitation cloud echoes simultaneously measured by the X-band
meteorological radar over EAR. The duration time of rain attenuation is estimated from thehorizontal distribution and moving speed of the X-band radar echoes. It is found that some of theduration time can be much longer than in Japan even for extremely large rainfall rate exceeding 50
mm/h [Takemoto et al., 2014, 2015a, 2015b]. The X-band radar observations also indicate that thecore of the precipitating clouds passes over EAR at the speed of about 5 m/s, on an average. Thisvalue is much slower than that of the precipitating clouds in Japan, which is usually 10-30 m/s, andseems to give rise to considerably longer duration time of the rain attention in both wet and dry
seasons. The slower moving speed is also confirmed by the atmospheric motions directly measured
by EAR in the higher altitude [Tama et al., 2014, 2015a, 2015b].

B. The Effects of Other Factors
Rapid changes in cross-polarization discrimination (XPD) of Ka-band satellite radio wave
signals caused by thunder-storm events are presented. Their yearly statistics and yearly variations are
discussed using the co-polar and cross-polar signals received for the past 17 years from 1990 to 2006.

4

The number of thunderstorm events and rapid changes in XPD shows large yearly variations in atime scale of about five or six years. These long-term yearly variations may be related to periodic
cycles of the equatorial climate, such as El Nino and La Nina, which tend to bring weak and strong
convective activities, respectively, to the summertime weather in Japan [Maekawa, 2016a].
(Y. Maekawa)F1.3 Mobile Radio Systems
A. Propagation for Cellular Systems
A new method for extracting the variation of multi-path fading, shadow fading, and path loss
components from measurement field strength data is presented. The method is based on wavelet
transformation and can extract precisely and easily each variation. The analyzed results based on
measurement data in urban macro-cellular environment are also shown [Imai et al., 2014a].
Path loss variation characteristics at 26 GHz band based on measured data with wavelet analysis
are shown. The analysis results clarify that the variation characteristics can be evaluated by taking
reflection paths at building walls into account, in addition to the ground waves and LOS paths[Sasaki et al., 2015a].
Characterization of correlation coefficient between elements of MIMO channel matrix withmovement by cumulative distribution is presented. The cumulative distributions are studied bytheoretical and simulation values under condition of LOS or not NLOS, and antenna configuration
with 2×2 and 4×4 line-line, 4×4 square-square. The results reveal some characteristics of thecorrelation coefficients under the case of movement on a straight line and with random direction[Kanemiyo et al., 2015].
Propagation characteristics for a MIMO adaptation transmission using an eigen-mode
transmission in line-of-sight of street microcell environments by computer simulations are presented[Q. H. Nguyen et al., 2015]. And small-scale and large-scale propagation characteristics for spatial
polarized MIMO using the eigen-mode transmission in line-of-sight of street microcell environments
are also presented. As the propagation characteristics for the eigen-mode transmission, the weight
polarization ratios of antenna, power distribution ratios, and SNR characteristics for the each stream
are revealed by computer simulations [Q. H. Nguyen et al., 2016].
Frequency-agile path loss models for urban street canyons are presented. The models arefloating intercept (FI), fixed reference (FR), and ITU-R M.2135 urban microcellular (UMi)line-of-sight (LOS) and Manhattan-grid non-LOS (NLOS) models. These models are parameterizedbased on channel sounding campaigns in three cities covering radio frequencies ranging from 0.8 to
60 GHz. Applicability of the proposed models to other street canyons is also discussed using
independent path loss measurements [Haneda et al., 2016]. Improvement of ray tracing in urban
street cell environment of Non Line-of-Site (NLOS) with consideration of building corner and its
surface roughness is presented. Propagation characteristics for a MIMO adaptation transmission
using an eigen-mode transmission in line-of-sight of street microcell environments are clarified bycomputer simulations using the proposed ray tracing model [Omaki et al., 2016].
The measurement results of the outdoor urban cellular wideband channels at 11 GHz arepresented. The measurements at various urban cellular environments that are classified into
macrocell, microcell and street-cell were conducted. And large scale characteristics of 11 GHz
wideband channels including path losses, shadowing, cell coverage, polarization properties anddelay spread are presented [Kim et al., 2015a].
B. Channel Estimation and Channel Sounding Method
Development of 24 x 24 MIMO channel Sounder are introduced. And an example of channel
measurement and modeling in urban residential area is presented [Takada et al., 2016].
A wideband full polari-metric directional channel measurement results at 58.5 GHz in a small
office room environment assuming an indoor access-point scenario in the next generation mobile

5systems are presented. The delay resolution was 2.5 ns, and the double directional angularcharacteristics are achieved by rotating high gain horn antennas at both sides of transmitter andreceiver. By identifying scattering objects from the measurement data analysis, some important
observations about the channel properties are also reported [Kim et al., 2015b].
Novel clustering approach which utilizes scattering points obtained from themeasurement-based ray tracer is proposed. The performance of the algorithm is evaluated with 11
GHz channel sounding data in an indoor environment and good performance of the proposed method
is shown [Hanpinitsak et al., 2016].
11 GHz band MIMO channel measurements are conducted in a line-of-sight (LoS) indoor
environment to clarify the characteristics of diffuse scatterings in the higher frequency band. The
frequency, angular, and the polarization domain dense multipath component propagation parameters
are estimated by using the RiMAX-based estimator. The result is expected to be utilized for thenovel MIMO channel model proposal in the higher frequency band that includes the contribution ofdense multipath components [Saito et al., 2016].
C. Formulations of Mobile Propagation
A formulation model for generating path shadowing number due to pedestrian walking insidewalks of a straight road is presented. It is shown that the path shadowing number can be used inan evaluation of path shadowing loss due to moving people [Nishii et al., 2014].
D. Machine-to-Machine/Infrastructure Propagation
A regression formula of propagation loss in obliquely crossed road for Inter-vehiclecommunications is proposed. It is revealed that the angle between two straight roads is a variable
parameter, but there is no shadowing in any propagation path. [Kanda et al., 2014].
E. Indoor/Outdoor-to-Indoor Propagation
A new method that uses radio data obtained from users' daily lives to estimate material
parameters for precisely modeling indoor radio propagation is presented. Experimental evaluations
demonstrated it decreased the number of data items needing to be collected [Inomata et al., 2014].
An indoor propagation model for TV white space (TVWS) is developed, which is useful forevaluating secondary-secondary interference in TVWS scenarios, and its empirical parameters arederived according to measurement results. The proposed model is based on components of freespace path loss, penetration losses of walls and floors, an attenuation coefficient against distance,
and an attenuation constant [Yamada et al., 2014a].
The characteristics of direct and scattered waves based on a measurement at 3.35 GHz in anindoor environment are investigated. The characteristics of each scattered ray such as the received
level, delay time, and azimuth angle of arrival (AOA) are shown [Kitao et al., 2014]. In order to takethe impact of pedestrians on the channel model into consideration, the estimation method of clusters'
power variation properties is presented. The method is based on the MIMO channel sounding
experiments in a cafeteria in a weekday lunch time in the 3 GHz band assuming the use of LTE
based cellular systems [Saito et al., 2014e].
A spatio-temporal channel model is proposed based on measurement channel data obtained at
3.35 GHz in an indoor environment. The model includes the characteristics of each scattered raysuch as the received level, delay and azimuth angle of arrival (AOA). The model represents thesecharacteristics by a log normal distribution and gradient linear lines [Kitao et al., 2015a]. The large
scale parameters of wideband multipath channels based on extensive measurement campaigns invarious indoor environments are presented. The measurements are conducted with a wideband
multiple-input multiple-output channel sounder having a bandwidth of 400 MHz at 11 GHz.
Polarization characteristics of path-loss, shadowing, cross-polarization power ratio, delay spread andcoherence bandwidth are characterized [Kim, et al., 2014].

6

In order to evaluate outdoor-to-indoor propagation characteristics, the performance of atheoretical analysis method that is a hybrid of ray-tracing and physical optics is evaluated withrespect to the calculation accuracy. As the results, the impact on the accuracy and computationalburden are shown [Imai et al., 2014b]. Elevation directional channel properties at a base station (BS)in a microcell outdoor-to-indoor environment which is significant for 3D-MIMO using 2D array
antennas are investigated based on measurement results using a vector channel sounder. The
properties of the elevation angular spread (ESD) and mean Elevation angle of Departure (EoD) are
specifically shown [Omaki et al., 2014a].
Investigations on an outdoor-to-indoor penetration loss between measured result and the result
by a hybrid method of ray-tracing (RT) and physical optics (PO) (RT-PO method) are presented. It isshown that the measured result and RT-PO method agree well with each other than the 3GPP model[Kimoto et al., 2015a]. The frequency characteristic of radio propagation loss at the bands from 0.8
to 4.7 GHz in outdoor-to-indoor environment is studied. As the results, a new path loss model
modified from 3GPP model considering an indoor penetration loss factor is presented [Kimoto et al.,2015b]. A new model for predicting the outdoor-to-indoor penetration loss is presented. The model
can predict by the simple equation with only the incident angle and the transmit distance and show
more accurate estimation than the 3GPP model [Nishimori et al., 2015], [Kimoto et al., 2016].
In order to clarify frequency dependency of path loss and channel properties, outdoor-to-indoor
path loss characteristics are investigated based on the measurement from 0.8 to 37 GHz in urban
microcell scenario. An extension of conventional O2I models is presented [Imai et al., 2016a].
Outdoor-to-indoor channel characteristics at 20 GHz band are clarified based on the measurement
using a channel sounder with a 50 MHz bandwidth. The propagation mechanism is also analyzed
based on estimating single scattering positions of multipath [Imai et al., 2016b], [Tran et al., 2016].
An O2I channel measurement result at 58.5 GHz assuming an outdoor hotspot access scenario in 5G
mobile systems and WLANs is presented. Comparing the measurement results with ray-tracing
simulation, dominant propagation mechanisms are identified. From the analysis, the propagation
mechanism of eight multi-path clusters is identified [Kim, et al., 2016a].
F. Blocking Effect of Human Bodies
Evaluations of 4x2 MIMO channel performance as propagation paths are usually shadowed bymoving people in an indoor environment is evaluated. It is described that the population density is avariable parameter in it [Mugiura et al., 2014].
A method of analyzing characteristics of human body shadowing based on the calculation of
the scattering from a lossy dielectric flat plates using uniform geometrical theory of diffraction(UTD) is presented. The effectiveness of the proposed method are shown by comparing between
calculated results and measured results [Tran et al., 2014b, 2015].
Long-term fading, shadow fading, and fast fading characteristics of path loss at 4.7 and 26.4
GHz in a crowded area with pedestrians are presented. It is revealed that these fading characteristics
of measured path loss broadly match the Nakagami-Rice distribution, and K-factor becomes low
with the increase in frequency from the results of the analysis with two frequencies [Nakamura et al.,2016].
Frequency characteristics of change in received level when pedestrians walk in indoor
environment are investigated experimentally to clarify influence of human body shadowing in higher
frequency band. Measurements are performed at 0.81GHz, 2.2 GHz and 19.85 GHz in indoor
environment [Kitao et al., 2016](N. Kita)
G. Millimeter-wave, THz and Optical Propagation
Assuming the adoption of the higher frequency band for future cellular systems than thecurrently used spectrum such as 800MHz, 2GHz, 3GHz, etc., the radio propagation in the
millimeter-wave in cellular mobile radio system has been actively studied.
A model for predicting path loss from the microwave band to the millimeter wave band forstreet microcell environments is presented. Developed on the basis of measurement results, the7

model uses visibility to predict path loss characteristics. The model reduces the root mean squareerrors of prediction results by more than 2.5 dB at bands above 26 GHz, demonstrating its ability to
predict measurement results accurately [Sasaki et al., 2015b].
A site general type path loss prediction model for fifth-generation (5G) system radio link design
is investigated for the frequency band above 6GHz in a non-line-of-sight (NLOS) microcell
environment. Based on measurement data, extending the applicable frequency range of the path loss
prediction model for a hexagonal layout in a NLOS microcell environment for under 6 GHz, which
is defined in Report ITU-R M.2135, is investigated. The root mean square of the prediction error(RMSE) of the original M.2135 prediction model increases with an increase in frequency; however,
the model modifies the frequency term of M.2135 which improves the RMSE at higher frequencies[Kitao et al., 2015b].
The 5G mobile communication systems will benefit immensely with the extension of theiroperation to millimeter-wave bands. To this end, understanding the system-level performance of
millimeter-wave cellular networks carries critical importance. The average signal-to-interferenceplus noise ratio (SINR) distribution (geometry) performance for indoor and outdoor mobile stations(MSs) in millimeter-wave cellular networks using 3GPP system-level simulations is investigated in apaper. The authors consider urban micro (UMi) and urban macro (UMa) environments for ourevaluations. Simulation results show that, when operating at 60 GHz or higher frequencies, almost
all the indoor MSs and more than 35% (65%) of outdoor MSs experience geometry performance lessthan 0 dB, in UMi (UMa) environments [Rupasinghe et al., 2016].
Path loss characteristics in an indoor office environment are also studied. It is clarified that thepath loss exponents vary depending on the frequency and the floor height when Tx and Rx areplaced on the same floor. A prediction formula is developed for the frequency characteristics of pathloss exponents by using the measurement results and it is confirmed that it can predict measurement
results more accurately than conventional formulas. In particular, it can improve the RMS prediction
error of 3.7 dB in 37 GHz bands [Sasaki et al., 2016a]. Floor penetration loss characteristics andtheir frequency dependency are analyzed by measuring in multiple frequency bands, including thoseabove 6 GHz, in an indoor office environment. Measurement and analysis results show that the floor
penetration loss depends on two dominant components: paths through floors and outside buildings. It
was clarified that the characteristics of these paths determine the frequency dependency of the floor
penetration loss [Sasaki et al., 2016b].
Propagation characteristic from outdoor to indoor is another topic of interest in the highfrequency band. A paper proposed the path loss model which can cover the high frequency bands
above the 6 GHz. The path loss characteristics are analyzed on the basis of measurement results
obtained using the 8 to 37 GHz band in outdoor-to-indoor environments. It is clarified that thecharacteristics depend on incident angle of azimuth, incident angle of elevation and frequency. Bytaking these dependencies into account, the proposed model can decrease the root mean square errorof prediction results to about from 2 dB to 6 dB in the 8 to 37 GHz band [Inomata et al., 2015].
The measurement results of outdoor-to-indoor path loss characteristics in multiple frequency bands
from microwave to millimeter wave are described. It is clarified in the paper that the path loss
characteristics depend on frequency. Moreover, ray tracing is used to analyze the propagation
phenomena causing frequency dependence. A comparison between measured and calculated results
clarified the dominant paths that are multiple reflected at an outdoor building and then diffracted into
building. These results show that the value of the root mean square error is about from 4 dB to 8 dB
in 0.8 to 37 GHz band. The authors confirm that these paths are dominant and affect the frequency
dependence of outdoor-to-indoor path loss [Inomata et al., 2016].
High frequencies such as high SHF (above 6 GHz) and EHF (30-100 GHz) are expected to be
applied for outdoor or indoor small cell; hence it is critically important to investigate thecharacteristics of propagation and model it. Additionally, characteristics of ‘Outdoor-to-Indoor (O2I)
propagation’ and its modelling are necessary from system design point of view. A report presents
extensive investigation for “Extension of 3GPP model below 6 GHz” [Imai et al., 2015b].

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The frequency dependency characteristics of path loss was obtained based on the measured data.
In order to analyze the frequency dependency, measurements are carried out with multiple frequency
bands from 0.8 GHz to 37.1 GHz. The measurement environments are a street canyon and an indoor
office, which respectively correspond to an urban micro cell and an indoor hot spot of mobile
communication system scenarios. On the basis of the obtained measurement results, path loss
characteristics are clarified and path loss models are proposed for the street canyon and indoor officeenvironments. The models validity is also verified [Sasaki et al., 2016c].
Fading and shadowing in the high frequency band have also been analyzed. In the highfrequency bands, besides the higher propagation losses, the propagation channel tends to suffer more
severe shadowing by pedestrians in the environments. Measurements in the 26GHz band was carriedout in an indoor quasi-static environment for figuring out the received power characteristics of theupper SHF band. The results show that the more severe received power variation occurred in the
26GHz band compared with the 2GHz band [Saito et al., 2014a]. Tran et al. [2014a] clarify basic
propagation characteristics and shadowing loss due to human body shadowing in the SHF (over 6GHz) bands based on measurements [Tran et al., 2014a].
One important issue to enable a high frequency (over 6GHz) band is clarifying the propagation
characteristics in the bands. A paper presents the channel characteristics in the 20 GHz band for anindoor office environment. Measurements are performed using a channel sounder in the 20 GHz
band with a 50-MHz-bandwidth orthogonal frequency-division multiplexing signal. A 19 dBi hornantenna is rotated in azimuth and elevation on the receiver side in order to measure the power delay
profile (PDP) at each angle. By combining all the PDPs, the channel characteristics are estimated as
if using an omni-directional antenna. The measured and estimated results show that the path loss
values are lower than those in free space. The averages of the delay spread, azimuth angle spread,and elevation angle spread are 60.4 ns, 64.7 degrees, and 3.6 degrees, respectively. The standard
deviations of the delay spread, azimuth angle spread, and elevation angle spread are 9.7 ns, 10.7
degrees, and 3.1 degrees, respectively [Tran et al., 2015b].
Ray-tracing is one of the most general method to analyze propagation characteristics in wirelesscommunication systems. The usability of the method in the high frequency was examined. In a paper,
the characteristics of radio propagation loss in a street cell environment for high-SHF and EHF
bands are investigated using Ray-Tracing (RT) method. The accuracy of RT calculation is evaluatedby comparing with measurement result. The trends of the accuracy are different between
Line-of-Site (LOS) and Non Line-of-Site (NLOS) situations and between different routes. For
further investigation, the number of rays in RT simulation is studied for the purpose of improving
the accuracy [Omaki et al., 2014a, 2015a, 2015b].
Frequency identification for the mobile communication system in 275-450 GHz was started in
the World Radiocommunication Conference 2015. Therefore, propagation model is required toenable sharing and compatibility studies between the land-mobile, fixed and passive services. In thisstudy, indoor propagation characteristics at 300 GHz is measured and analyzed to develop path loss
models. Measurements have been carried out in office and corridor environments in line-of-sight
situation, and the path loss coefficients are extracted. The coefficient of office environment isroughly identical with the free space loss of N=20, and the coefficient of corridor environment wasslightly decreased to N=19.5 [Sawada et al., 2016].
Dominant propagation mechanisms in an outdoor open area environment through the channel
measurement and ray-tracing simulation at an mm-wave band of 58.5 GHz assuming an outdoor
hotspot access scenario in 5G mobile systems and WLANs are presented. Extracted statisticalchannel model parameters of the random components by using ray-tracing simulation are alsopresented [Kim et al., 2016b].
H. Others
MIMO-related propagation studies were actively carried out in this period. Massive MIMO
enables the improvement on the transmission rate without increasing the burden on the signal
processing by employing a large number of antennas at a base station. Even if the interference9cancellation techniques are not employed, the interference signal can be mitigated thanks to a narrow
beam by the massive MIMO transmission. An actual propagation channel was measured by using a
wideband channel sounder with 96 elements in 2 GHz band at small cell environment. Moreover, theeffectiveness of the interference rejection when using antenna sector selection was verified [Kataoka
et al., 2014]. Real propagation channels for massive MIMO are measured by using a wideband
channel sounder with horn antenna in 20-GHz band in an actual indoor propagation environment.
Moreover, the performance of the interference rejection is evaluated when virtual circular array
antenna with 24 elements is assumed [Kataoka et al., 2015a].
The interference reduction performance between zero forcing (ZF) and maximum ratio
combining is compared. Moreover, the characteristics with the smaller number of antennas at thebase station are clarified, in order to simplify the burden of signal processing on the ZF algorithm[Kataoka et al., 2015b]. An actual propagation channel was measured by using a wideband channelsounder with cylindrical array in 2 GHz band at a microcell environment. Moreover, theeffectiveness of the interference rejection is verified when using the hybrid algorithm which employs
the MRC on the analog part and zero forcing (ZF) in the digital processing part [Kataoka et al.,2015c, 2015d, 2015e].
The interference reduction performance is investigated when considering the cylindrical arraybased massive MIMO in a real micro cell environment. The channel state information is obtained byusing a wideband channel sounder in a 2 GHz band at an urban area. In the paper, the interference
reduction performance between zero forcing (ZF) and maximum ratio combining is compared. The
characteristics with the smaller number of antennas at the base station is also investigated, in order tosimplify the burden of signal processing on the ZF algorithm [Nishimori et al., 2016].
2GHz MIMO channel measurement was carried out in an urban railway station vicinity. As theresult of comparison between the measurement result and ITU-R M.2135 channel model, it was
shown that the channel capacity of LoS case was underestimated in the channel model. In the NLoS
case, the variability of the capacity was different when the BS antenna spacing was changed [Saito etal, 2014b]. Channel sounding experiments outside a crowded urban railway station are carried out inthe 2 GHz band assuming the use of LTE-based cellular systems. To elucidate the influence ofpedestrians on the channel properties, the measurements were carried out both in the daytime and in
the midnight. The measurements result showed that the received power decreased about 4-5 dB in
the daytime due to the shadowing by the pedestrians. In addition, the delay spreads decreased and
AoAelv and AoDelv spreads increased in the daytime due to the change of propagation environment
caused by the pedestrians [Saito et al., 2014c].
In crowded environments, propagation paths are frequently shadowed by moving objects, suchas pedestrians or vehicles. These shadowing effects can cause time variations in the delay andangle-of-arrival (AoA) characteristics of a channel. A method for modeling the shadowing effects ofpedestrians in a cluster-based channel model is proposed. The proposed method uses cluster power
variations to model the time-varying channel properties. A novel method for estimating the cluster
power variation properties from measured data is also proposed. In order to validate the proposed
method, channel sounding in the 3GHz band is conducted in a cafeteria during lunchtime. The
results for the K parameter, delay spreads, and AoA azimuth spreads are compared for the measured
data and the channel data generated using the proposed method. The results indicate that the
time-varying delay-AoA characteristics can be effectively modeled using our proposed method[Saito, et al. 2014d].
The user rate performance of massive MIMO small cells in hot-spot areas is evaluated. In
particular, with the use of the 28GHz millimeter wave band ray-tracing channel data generated
according to the realistic map in Shinjuku, Tokyo, Japan, the user-specific rates in an area of 150 m
× 120 m is investigated. The results show promising rate performances with the use of a variety of
beamforming schemes in both cellular and distributed manners [Wang et al., 2016].
The performance analysis of a proposed auto-regressive (AR) model-based linear predictor
algorithm with Kalman filtering (KF) is reported in a paper. The relationship between the optimum10AR order and the channel correlation coefficient is investigated by means of the Akaike Information
Criterion (AIC). Through our analysis, 2nd-order differential model based on the AR model-based
linear predictor algorithm with KF has the best performance and prediction accuracy. Its
performance is about 0.5dB better than a linear predictor algorithm [Yamada et al., 2014b].
To develop an accurate and reliable method to estimate field distributions in train cars so as toadvance radio link design of wireless LANs operating inside the cars, effects of reflected waves due
to tunnel wall and/or train passing on opposite track on propagation characteristics inside thehigh-speed train cars in a typical railway tunnel is studied. Field distributions created by a 2.4 GHz
band wireless transmitter inside cars are analyzed and exemplary propagation characteristics are
determined statistically from large-scale numerical analysis results [Shirafune et al., 2014, 2015].
A method named Double Aperture Field Method for calculating electrical field passing throughtwo apertures between transmitting and receiving points is proposed. The comparison between
calculations and experiments data carrying out in an anechoic chamber is shown. The proposed
method has excellent agreement with experiments [Hasegawa and Taga, 2015]. Also formulations
named Single Aperture Field Method is proposed for calculating electrical field passing throughapertures between transmitting and receiving points. This formulation can be used with ray tracing
method, because of the propagation path through the aperture radiated from a center of aperture as asecondary source point. The comparison between calculations and experiments carrying out in an
anechoic chamber is shown. The proposed method has excellent agreement with experiments[Kondo and Taga, 2015].
(H. Iwai)

F2 Remote Sensing
F2.1 Atmosphere
A. Ground-based Remote Sensing Studies
Atmospheric radars generally called MST (mesosphere, stratosphere, and troposphere) radars,
ST (stratosphere and troposphere) radars, or Wind Profiling Radars (WPR) are capable ofcontinuously monitoring three-dimensional winds, waves, turbulence, and atmospheric stability over
the wide altitude range. This excellent capability has been used extensively to study various
dynamical disturbances in the Earth's atmosphere.
The middle and upper atmosphere radar (MU radar) is a major observation facility in the
Shigaraki MU Observatory of the Research Institute for Sustainable Humanosphere (RISH), Kyoto
University. The MU radar is an excellent system having 25 receiver channels to carry out
observation using a spaced antenna (SA) technique. 50MHz band atmospheric radars can detect clear
air echoes and hydrometeor echoes simultaneously. However, in order to calculate spectral
parameters of the clear air echo accurately, the clear air echo must be separated from thehydrometeor echo well. Gan et al. [2015] proposed methods (top method and two-echo method) for
calculating the spectral parameters in precipitation region. The top and two-echo methods are used
when raindrops or solid hydrometeors with small and large echo intensities exist, respectively.
Measurement results obtained by the vertical beam of MU radar during a precipitation event on 26
October 2009 demonstrate that the top and two-echo methods are useful for reducing errors ofspectral parameters.
Strong meteor trail echoes are interferences in the wind velocity estimates made frommesosphere radar observations. Contaminated spectra are detected by their discontinuity and areremoved at the risk of greater fluctuations of spectra, leading to a severe reduction of thesignal-to-noise ratio (SNR) and inaccurate wind estimates for weak atmospheric echoes. Hashimoto
et al. [2014] presents an adaptive signal processing technique for the suppression of spectral
contaminations by meteor trail echoes. The method is based on the norm-constrained anddirectionally constrained minimization of power (NC-DCMP), which balances the capability ofcanceling the clutter and the robustness of beam shaping, at the cost of a slight decrease in the SNR,

11

which can be determined in advance. Simulation results show that with a 3-dB decrease of the SNR
being allowed, the method improves the signal-to-interference ratio (SIR) by 15 dB, giving windestimates that are about 8 m/s better in terms of root-mean-square error and providing 4 times aswide an observable range when compared with the results of the ordinary non-adaptive beamforming
method. The results for an actual observation show that the improvement of both the SIR and theobservable range are achieved as in the simulations, which implies that the method should provide
the simulated accuracy for the estimation of wind velocity from actual observations.
Chen et al. [2016] reports the ﬁrst use of a multi-frequency range imaging (RIM) technique forobserving E-region ﬁeld-aligned irregularities (FAIs) in the mid-latitude ionosphere. The MU radar
was used to conduct experiments with ﬁve equally spaced frequencies between 46.25 and 46.75
MHz Excellent RIM performance such as the ability to resolve several striations in an echo region of
FAIs was demonstrated. However, sidelobe echoes caused by pulse coding mechanisms wereoccasionally observed at altitudes above and below the source regions in the coded data. Therefore, aprocedure was developed according to one of the calibration approaches to identify and remove suchkind of sidelobe echoes, which was shown to be applicable for the complementary-coded data.
Many experimental studies were conducted using the MU radar. The refractivity turbulence inthe troposphere was detected and quantified from radiosonde and VHF band radar data [Luce et al.,2014]. Balloon data processing methods based on Thorpe sorting can be applied for a direct
identiﬁcation of turbulent layers from the in situ proﬁles. The MU radar can be operated inrange-imaging mode for detecting and monitoring turbulent layers at high time and range resolutions(of the order of 10s and a few tens of meters, respectively). It is demonstrated that radar and balloon
observations of turbulence are consistent between each other and that new insights on troposphericturbulence can be obtained by the two techniques as stand-alone systems.
Deep turbulent layers can sometimes be observed on the underside of clouds that extend above
upper-level frontal zones. The numerically simulated midlevel cloud-base turbulence (MCT) was
compared with a turbulent layer detected by the MU radar during the passage of an upper-level front
topped by clouds [Kudo et al., 2015]. The simulations were initialized with thermodynamic
parameters derived from simultaneous radiosonde data. It was found that some important features ofthe simulated MCT (such as the scale of convection and vertical wind velocity perturbations) agreed
quantitatively well with those reported in radar observations.
Based on the Program of the Antarctic Syowa MST/IS Radar, the first
Mesosphere–Stratosphere–Troposphere/Incoherent Scatter (MST/IS) radar in the Antarctic region,
called PANSY radar, has been installed. Sato et al. [2014] reports the project's scientific objectives,technical descriptions, and the preliminary results of observations made to date. The PANSY radar isdesigned to clarify the role of atmospheric gravity waves at high latitudes in the momentum budgetof the global circulation in the troposphere, stratosphere and mesosphere, and to explore thedynamical aspects of unique polar phenomena such as polar mesospheric clouds (PMC) and polar
stratospheric clouds (PSC). The katabatic winds as a branch of Antarctic tropospheric circulation andas an important source of gravity waves are also of special interest. Moreover, strong and sporadicenergy inputs from the magnetosphere by energetic particles and field aligned currents can bequantitatively assessed by the broad height coverage of the radar which extends from the lower
troposphere to the upper ionosphere.
The PANSY radar is a large VHF monostatic pulse Doppler radar operating at 47 MHz,consisting of an active phased array of 1045 Yagi antennas and an equivalent number oftransmit–receive (TR) modules with a total peak output power of 500 kW. From engineering pointsof view, the radar had to overcome restrictions related to the severe environments of Antarctic
research, such as very strong winds, limited power availability, short construction periods, andlimited manpower availability. These problems were resolved through the adoption of speciallydesigned class-E amplifiers, light weight and tough antenna elements, and versatile antennaarrangements.

12

At the first stage, the PANSY radar was installed at Syowa Station (69.0S, 39.6E) in early 2011,
and is currently operating with 228 antennas and modules. Although the radar is currently operatingwith only about a quarter of its full designed system components, interesting results on the Antarctic
troposphere, stratosphere and mesosphere, such as gravity waves, multiple tropopauses associatedwith a severe snow storm in the troposphere and stratosphere, and polar mesosphere summer echoes(PMSE) have been obtained.
Characteristically strong vertical wind disturbances (VWDs) with magnitudes larger than 1m/s
were observed in the Antarctic troposphere using PANSY during 15–19 June 2012 [Tomikawa et al.,2015]. In the same period, two synoptic-scale cyclones approached Syowa Station and caused astrong wind event (SWE) at the surface. The VWDs observed during the SWE at Syowa Station had
a nearly standing (i.e., no phase tilt with height) phase structure up to the tropopause and a power
spectrum proportional to the 25/3 power of frequency. On the other hand, the observed VWDs were
not associated with systematic horizontal momentum fluxes. Meteorological fields around Syowa
Station during the SWE were successfully simulated using the Nonhydrostatic Icosahedral
Atmospheric Model (NICAM). A strong VWD was also simulated at the model grid of 70.0S, 40.0E
in NICAM, which had a standing phase structure similar to the observed ones. An analysis based on
the Froude number showed that the simulated VWD was likely due to a hydraulic jump leeward of
the coastal mountain ridge. The Scorer parameter analysis indicated that the observed VWDs at
Syowa Station during 16–17 June 2012 were likely due to the hydraulic jump similar to that in
NICAM. On the other hand, a possibility of lee waves was also suggested for the VWD observed on
18 June 2012.
Multiple tropopauses (MTs) defined by the World Meteorological Organization are frequently
detected from autumn to spring at Syowa Station [Shibuya et al., 2015]. The dynamical mechanismof MT events was examined by observations of PANSY, and of radiosondes on 8–11 April 2013.
The MT structure above the first tropopause is composed of strong temperature fluctuations. By adetailed analysis of observed three-dimensional wind and temperature fluctuation components, it isshown that the phase and amplitude relations between these components are consistent with thetheoretical characteristics of linear inertia–gravity waves (IGWs). Numerical simulations were
performed by using a nonhydrostatic model. The simulated MT structures and IGW parametersagree well with the observation. In the analysis using the numerical simulation data, it is seen that
IGWs were generated around 65S, 15E and around 70S, 15E, propagated eastward, and reached theregion above Syowa Station when the MT event was observed. These IGWs were likely radiatedspontaneously from the upper-tropospheric flow around 65S, 15E and were forced by strong
southerly surface winds over steep topography (70S, 15E). The MT occurrence is attributable tostrong IGWs and the low mean static stability in the polar winter lower stratosphere. It is also shownthat nonorographic gravity waves associated with the tropopause folding event contribute to 40% of
the momentum fluxes, as shown by a gravity wave–resolving general circulation model in the lower
stratosphere around 65S. This result indicates that they are one of the key components for solving
the coldbias problem found in most climate models.
Nishiyama et al. [2015] reported height and time variations in polar mesosphere winter echoes(PMWE) based on the PANSY radar observations. PMWE were identified for 110 days from March
to September 2013. PMWE occurrence frequency increased abruptly in May when two solar proton
events occurred. PMWE were also observed even during periods without any solar proton events,suggesting that a possible cause of the PMWE is ionization by energetic electron precipitations. The
monthly mean PMWE characteristics showed that occurrence of PMWE were mainly restricted to
sunlit time. This fact indicates that electrons detached from negatively charged particles play animportant role. While PMWE below 72 km in altitude completely disappeared before sunset, it was
detected above that altitude for a few hours even after sunset. This height dependence in the altitude
range of 60–80 km can be explained qualitatively by empirical effective recombination rates.
Inertia-gravity waves (IGWs) are an important component for the dynamics of the middle
atmosphere. However, observational studies needed to constrain their forcing are still insufficient13especially in the remote areas of Antarctic region. One year of observational data (January to
December 2013) by the PANSY radar of the wind components (vertical resolution of 150m andtemporal 5 resolution of 30 minutes) are used to derive statistical analysis of the properties of IGWs
with short vertical wavelengths (≤ 4km) and ground-based periods longer than 4 hours in thelowermost stratosphere (height range 10km to 12km) with the help of the hodograph method[Mihalikova et al., 2016]. The annual change of the IGWs parameters are inspected but nopronounced year cycle is found. The year is divided into two seasons (summer and winter) based on
the most prominent difference in the ratio of Coriolis 10 parameter (f) to intrinsic frequency (ωˆ)
distribution. Average of f /ωˆ for the winter season is 0.40 and for the summer season 0.45 and theaverage horizontal wavelengths are 140km and 160km respectively. Vertical wavelengths have an
average of 1.85km through the year. For both seasons the properties of IGWs with upward anddownward propagation of the energy are also derived and compared. The percentage of downward
propagating waves is 10.7% and 18.4% in the summer and winter season respectively. This seasonalchange is more than the one previously reported in the studies from mid-latitudes and model-based
studies. It is in agreement with the findings of past radiosonde data based studies from the Antarctic
region. In addition, using the so-called dual-beam technique, vertical momentum flux and thevariance of the horizontal perturbation velocities of IGWs are examined. Tropospheric disturbancesof synoptic-scale are suggested as a source of episodes of IGWs 20 with large variance of horizontal
perturbation velocities, and this is shown in a number of cases.
The 47-MHz Equatorial Atmosphere Radar (EAR) has been operated at Kototabang (0.20S
geographic lat., 100.32E geographic lon., and 10.4S geomagnetic lat.), West Sumatra, Indonesia
since 2001 and has been very successfully used for the study of equatorial atmosphere dynamics.
Observations of wind components and convection systems were made using suite of instruments
centered on the EAR during April-May 2004 in the first Coupling Processes in Equatorial
Atmosphere (CPEA) campaign [Dhaka et al., 2014]. Analysis of five convection events revealed thatvertical wavelength of gravity waves mostly dominated in the range of 1-3 km between 10 and 20
km heights immediately after passing the convective storm over the radar sites.
Using the fan sector backscatter maps of 47 MHz EAR, the spatial and temporal evolution ofequatorial plasma bubbles (EPBs) were examined to classify the evolutionary-type EPBs from thosewhich formed elsewhere and drifted into the ﬁeld of view of radar [Ajith et al., 2015]. In general,
both the evolving-type and drifting-in EPBs exhibit predominance during the post-sunset hours ofequinoxes and December solstices. The responsible mechanisms for the genesis of fresh EPBs
during post-midnight hours were discussed in light of equatorward meridional winds in the presenceof weak westward electric ﬁelds.
The unusual evolution of fresh and intense ﬁeld-aligned irregularities (FAI) near sunrise
terminator which further sustained for more than 90 min of post-sunrise period was observed by
EAR during a minor geomagnetic storm period [Tulasi et al., 2015a]. These FAI echoes were
initially observed around 250–350 km altitudes, growing upward under eastward polarizationelectric ﬁelds indicating the plasma bubbles that are fully depleted along the ﬂux tube. A minor
geomagnetic storm was in progress which did not appear to cause any large electric ﬁeld
perturbations at preceding post-sunset to midnight period over Indonesian sector.
Vertical rise velocities of post-midnight FAIs at low geomagnetic latitudes have been examinednear the June solstice by using two-dimensional maps of F region FAI echoes observed with the
EAR for 3 years starting in May 2010 [Dao et al., 2016]. Fifteen freshly growing FAIs ware found at
post-midnight between May and August during the 3 years. The rise velocities of FAIs are smaller at
post-midnight than at post-sunset, and most post-midnight FAIs do not exceed an altitude of 450 km.
The equatorial zonal electric ﬁeld responses to prompt penetration of eastward convection
electric ﬁelds (PPEF) were compared at closely spaced longitudinal intervals at dusk to pre-midnight
sectors during the intense geomagnetic storm of 17 March 2015. At dusk sector (Indian longitudes),a rapid uplift of equatorial F layer to >550 km and development of intense equatorial plasma bubbles(EPBs) were observed [Tulasi et al., 2015b]. In contrast, at few degrees east in the pre-midnight14

sector (Thailand-Indonesian longitudes), no signiﬁcant height rise and/or EPB activity has been
observed. This study brings out the signiﬁcantly enhanced equatorial zonal electric ﬁeld in response
to PPEF that is uniquely conﬁned to dusk sector.
To reveal the temporal change of the equatorial ionization anomaly (EIA) asymmetry, amultipoint satellite-ground beacon experiment was conducted along the meridional plane of theThailand–Indonesia sector. Successive passes captured rapid evolution of EIA asymmetry, especiallyduring geomagnetic disturbances [Watthanasangmechai et al., 2015]. The penetrating electric fields
that occur during geomagnetic disturbed days are not the cause of the asymmetry. Instead, highbackground TEC associated with an intense electric field empowers the neutral wind to produce
severe asymmetry of the EIA. Such rapid evolution of EIA asymmetry was not seen during
nighttime, when meridional wind mainly controlled the asymmetric structures.
The solar energy can mainly be divided into two categories: the solar radiation and the solar
wind. The former maximizes at the equator, generating various disturbances over a wide height
range and causing vertical coupling processes of the atmosphere between the troposphere and middle
and upper atmospheres by upward propagating atmospheric waves. The energy and material ﬂows
that occur in all height regions of the equatorial atmosphere are named as “Equatorial Fountain.”
While, the electromagnetic energy and high-energy plasma particles in the solar wind converge into
the polar region through geomagnetic ﬁelds. Tsuda et al. [2016] propose to clarify these overall
coupling processes in the solar-terrestrial system from the bottom and from above throughhigh-resolution observations at key latitudes in the equator and in the polar region. In this proposal,
construction of large radar with active phased array antenna, called the Equatorial Middle and Upper
atmosphere (EMU) radar, is planned to construct in west Sumatra, Indonesia and participate inconstruction of the EISCAT_3D radar in northern Scandinavia are planned. The development of a
global observation network of compact radio and optical remote sensing equipment from the equator
to polar region is also planned.
Predawn plasma bubble was detected as deep plasma depletion by GNU Radio Beacon
Receiver (GRBR) network and in situ measurement onboard Defense Meteorological Satellite
Program F15 (DMSPF15) satellite and was conﬁrmed by sparse GPS network in Southeast Asia
[Watthanasangmechai et al., 2016]. In addition to the deep depletion, the GPS network revealed thecoexisting submesoscale irregularities. A deep depletion is regarded as a primary bubble.
Submesoscale irregularities are regarded as secondary bubbles.
A new digital receiver was developed for a 1.3-GHz range imaging atmospheric radar[Yamamoto et al., 2013]. The digital receiver comprises a general-purpose software-deﬁned radio
receiver and a commercial personal computer. Because the program code for real-time signal
processing is written in a popular programming language (C++) and widely used libraries, the signal
processing is easy to implement, reconﬁgure, and reuse. From radar experiments using a 1 micro-sec
sub-pulse width and 1 MHz frequency span, it is demonstrated that range imaging in combination
with oversampling, which was implemented for the ﬁrst time by the digital receiver, is able toresolve the ﬁne-scale structure of turbulence with a vertical scale as small as 100 m or ﬁner.
Using numerical simulations, a method for calculating the spectral parameters from Doppler
spectra collected by high-resolution wind proﬁler radars (WPRs) was investigated [Gan et al., 2014].
The proposed method has two steps. In the ﬁrst step, the echo range (Recho), in which the Doppler
spectrum point with peak intensity is contained and all the smoothed Doppler spectrum points haveintensities that are greater than the noise intensity, was determined. For producing the smoothed
Doppler spectrum, a running average with equal weight (RA) was used. In the second step, thespectral parameters were calculated using the Doppler spectrum points within Recho.
Yabuki et al. [2016] had constructed a scanning Raman lidar to observe the cross-sectional
distribution of the water vapor mixing ratio and aerosols near the Earth's surface, which are diﬃcult
to observe when a conventional Raman lidar system is used. The Raman lidar is designed for anighttime operating system by employing a ultra-violet (UV) laser source and can measure the water
vapor mixing ratio at an altitude up to 7 km using vertically pointing observations. The experimental

15

observations using the scanning lidar were conducted at night in the Shigaraki MU Observatory. The
root mean square error (RMSE) between the temporal variations of the water vapor mixing ratio by
the scanning Raman lidar and by an in-situ weather sensor equipped with a tethered balloon was
0.17 g/kg at an altitude of 100 m.

B. Space-based Remote Sensing Studies
The Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) is a successful
mission to observe vertical distributions of ozone and other atmospheric constituents in thestratosphere and mesosphere. The SMILES was operated a half year in the winter of 2009/2010 on
the Japanese Experiment Module “Kibo” of the International Space Station (ISS). The highly
sensitive measurements revealed a small perturbation of the ozone vertical distribution in themesosphere during a solar eclipse, which provide us a unique opportunity to study the mesosphericozone photochemistry [Imai et al., 2015a]. In addition to the high sensitivity, the SMILES data hasan advantage of diurnal variation measurement due to the non-sun-synchronous orbit of the ISS.
From the SMILES data, it becomes widely recognized that the diurnal variation of the ozone
distribution causes the sunset-sunrise difference of the ozone mixing ratio measured by the sensors
on satellites of sun-synchronous orbit [Sakazaki et al., 2015].
Baron et al. [2015] derived the global distribution of horizontal wind in the stratosphere andmesosphere by estimating the Doppler frequency of the atmospheric emission lines measured by
SMILES. Since stratospheric wind measurement is a unique aspect of submillimeter-wave limb
sounding, a number of submillimeter sounder for wind observation are now proposed in the world. A
concept of the future submillimeter satellite, SMILES-2, is proposed by Japanese group to observe
the winds in the stratosphere, mesosphere and lower thermosphere. SMILES-2 will also have acapability of measuring atmospheric constituents. The frequency bands and the sensitivity to theconstituents for SMILES-2 were studied [Suzuki et al., 2015].
F2.2 Hydrometeors and Other Particles
A. Ground-based Remote Sensing Studies
For the study of drop size distribution (DSD) of rainfalls, various ground-based instruments
such as a 2 dimensional video disdrometer (2DVD) and a disdrometer have been used, to count the
number of drops with a finite drop bin size.
Intraseasonal variations of precipitation and its microstructure are investigated using
measurements of the Equatorial Atmospheric Radar (EAR) facilities at Kototabang, west Sumatra,Indonesia [Marzuki et al., 2015]. Raindrop size distribution (DSD) observations are obtained from a
2D-Video Disdrometer (2DVD). Precipitation types are classiﬁed using 1.3-GHz wind proﬁler
observation, and are partitioned according to active and inactive convective phases of
Madden–Julian Oscillation (MJO). It is found that precipitation systems during the inactive phaseare more continental in nature than those during the active phase. Radar reﬂectivity during theinactive phase is larger than that during the active MJO phase, at the same rainfall rate. Thiscondition can limit the accuracy of radar-derived rainfall estimates for the tropics when applying asingle Z–R relation to the two MJO phases, particularly for deep convective rains.
B. Space-based Remote Sensing Studies
The Global Precipitation Measurement (GPM) Core Observatory, a joint mission between
NASA and the JAXA, was launched on Feb. 27, 2014. Two observation instruments are onboard thecore observatory: the Dual-frequency Precipitation Radar (DPR) developed by Japan, and the GPM
Microwave Imager (GPM) developed by the U.S. The DPR is a successor of the Precipitation Radar(PR) loaded onto the GPM’s predecessor, the Tropical Rainfall Measuring Mission (TRMM). The
35.5 GHz radar (KaPR) was additionally installed onto the PR at 13.6 GHz (KuPR) for highaccuracy observation. The role of core observatory is to improve the accuracy of precipitation
observation by microwave imagers on a constellation of satellites through simultaneous observations

16

with the radar and the microwave imager. Rain retrieval algorithms for the DPR have been
extensively studied by the science team.
Kubota et al. [2014] evaluates “at-launch” codes of DPR precipitation algorithms, which will be
used in GPM ground systems at launch, using synthetic data based upon the TRMM PR data.
Results from the codes (Version 4.20131010) of the KuPR-only, KaPR-only, and DPR algorithms
were compared with “true values” calculated based upon drop size distributions assumed in thesynthetic data and standard results from the TRMM algorithms at an altitude of 2 km over the ocean.
The results suggest that the underestimation of KaPR algorithm is caused by a problem in theattenuation correction method, which was verified by the improved codes.
A new attenuation correction method called the HB-DFR-SRT method (H-D-S method) has
been developed for DPR. The new method is based on Hitschfeld and Bordan’s attenuation
correction method (HB method), but the relationship between the specific attenuation k and theeffective radar reflectivity factor Ze (k–Ze relationship) is modified by using the dual-frequency
ratio (DFR) of Ze and the surface reference technique (SRT). The H-D-S method mitigates thenegative bias by means of the SRT. The attenuation correction methods were tested with a simple
synthetic DPR dataset [Seto et al., 2015]. The H-D-S method did not produce the best results forboth weak and heavy precipitation, but the results are stable. Quantitative evaluation should be donewith real DPR measurement datasets.
Awaka et al. [2016] describes the version 4 (V4) of the rain type classification algorithm
module for the GPM DPR and some statistical results on the rain type and on the detection of brightband (BB).

F2.3 Land
A. Land Surface
On May 24, 2014, ALOS2, the follow-on satellite of ALOS, was launched. The L-band
Synthetic Aperture Radar (PALSAR2) on ALOS2 provides images with the higher resolution (3m)and wider swath (50km) in high resolution mode as compared with the images of former L-band
SAR (PALSAR) on ALOS [Yamaguchi et al., 2014a, 2016a, 2016b, Yamaguchi, 2015]. After thelaunch, the initial functional confirmation and calibration operations were carried out. From
November 25, 2014, the regular provision of PALSAR2 observation data has started.
Since PALSAR2 has a function of polarimetric observation by utilizing horizontal (H) andvertical (V) polarized waves both in transmission and reception, full polarimetric data can beobtained. The observed polarimetric data is expected to be utilized for various remote sensing
applications.
Moriyama [2015] discusses the polarimetric calibration and assessment of polarimetric dataobtained by PALSAR2. The channel imbalance and cross-talks estimated from Amazon's
polarimetric data are reported and the polarimetric signatures of trihedral corner reflector before andafter polarimetric calibration are shown. Moreover, results from Tomakomai data was comparedwith that from Amazon data.
Fully polarimetric radar and its utilization and applications to various fields have been
investigated. The main topics were focused on the decomposition of fully polarimetric data sets
including the model-based three/four-component scattering power decomposition, which tries toincorporate 100% second order statistical polarimetric information [Chen et al., 2014a, 2014b, 2014c,
2014d, Cui et al., 2014a, 2014b, 2015, Xiao et al., 2014, Bhattacharya et al., 2015a, 2015b, Kusano
et al., 2015, Yamaguchi et al., 2016c].
Moreover, the expression method of decomposed polarization data with color was investigatedby Chiang et al. [2016].
The NICT has developed the second X-band airborne polarimetric and interferometric synthetic
aperture radar (Pi-SAR2) system (Yamaguchi et al. [2014b]). The polarimetric calibration has doneby Satake et al. [2015].
Because Pi-SAR2 uses two vertically placed antennas for V- and H-polarization, the17polarimetric phase is suffered with ground height difference. Moriyama et al. [2014a] proposed thephase compensation method to remove an interfering phase in Pi-SAR-X2 POLSAR data by using
the elevation data which is acquired with the slave-V antenna displaced in the cross-track direction(for interferometric observation). Moreover, Moriyama et al. [2014b] proposed the phasecompensation method based on the reciprocity principle to remove the phase error in Pi-SAR-X2
POLSAR data due to the mismatch between the flight navigation data and polarimetric raw data. The
experimental results showed the usefulness of these proposed methods.
The techniques for analysis using multi-baseline SAR data obtained by Pi-SAR2 including
SAR tomography have investigated by Kato et al. [2015], Yamada et al. [2016a, 2016b].
The applications of SAR data to environmental monitoring have been investigated.
Applications for snow and glacier monitoring were investigated by Park et al. [2014], Singh et al.
[2014a, 2014b], and Surendar et al. [2015]. For landslide, Shibayama et al. [2014, 2015], andYamaguchi et al. [2016d] were investigated. The applications for flood area and wetland[Yamaguchi et al.,2016e, 2016f], crop information [Singh, 2015], and debris evaluation [Koyama,
2016] were also investigated. The application for urban area monitoring were investigated by Sato etal. [2015, 2016a, 2016b] and Masaka et al. [2015]. These applications were utilized for damage
analysis by Kumamoto earthquakes [Yamaguchi et al., 2016g].
The results obtained using remote sensing data have to be compared with ground truth, andsome effects of environment also have to be evaluated by field experiments. Such fundamental
studies were done by Kobayashi et al. [2014], Watanabe et al. [2014], and Kato et al. [2014, 2015].

B. Subsurface Objects and Landmine Detection
During the past 80 years, ground-penetrating radar (GPR) has evolved from a skepticallyreceived glacier sounder to a full multicomponent 3D volume-imaging and characterization device.
Because of its high resolution, GPR is a valuable tool for quantifying subsurface heterogeneity, andits ability to see nonmetallic and metallic objects makes it a useful mapping tool to detect, localize,
and characterize buried objects. To improve the range resolution, the UWB antenna system has been
investigated [Liu et al., 2013]. To improve the ability to linear object detection, the hybrid
dual-polarization system has also investigated [Liu et al., 2015]. The signal processing of GPR has
also investigated for improvements tailored to actual situations [Feng et al., 2014, Yi et al., 2016].
Karlina et al. [2016] applied the compressive sensing to land mine detection. Not only to detect, butalso to map UXOs, the self-tracking total station with electromagnetic sensor has been investigated[Takahashi et al., 2014a].
The land mime detection using GPR is influenced from the interior change of soil property[Takahashi et al., 2014]. The ability to detect the change of soil property has been applied to theinterior soil heterogeneity [Takahashi et al., 2015, Takamura et al ,2016].
The GPR is being used for various purposes. Liu et al. [2014a] measure the thickness of snow
and ice. Zhu et al. [2014] applied the GPR for tree roots measurement. Liu et al. [2014b] applied for
concrete thickness measurement.
(A. Nadai)
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Omaki, N., K. Kitao, K. Saito, T. Imai, and Y. Okumura [2014a], “Experimental study on elevation
directional channel properties to evaluate performance of 3D-MIMO at base station in microcell
outdoor to indoor environment,” Proc. of 2014 IEEE International Workshop on Electromagnetics(iWEM 2014), pp.219-220, Sapporo, Japan, Aug.
Omaki, N., K. Kitao, T. Imai, and Y. Okumura [2014b], “Investigation of ray tracing accuracy instreet cell environment in high-SHF band,” Proc. of 2014 International Symposium on Antennas andPropagation (ISAP 2014), Dec.
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Proc. of 2015 European Conference on Antennas and Propagation, (EuCAP2015), pp. 1-4, Lisbon.
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method for between 0.8 and 37 GHz in street cell environment,” Proc. of 2015 International
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Omaki, N., T. Imai, K. Kitao and Y. Okumura [2016], “Improvement of ray tracing in urban street
cell environment of Non Line-of-Site (NLOS) with consideration of building corner and its surface
roughness,” Proc. of the 10th European Conference on Antennas and Propagation (EuCAP 2016),
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2GHz band in crowded small-cell environment,” Proc. of 2014 European Conference on Antennas
and Propagation (EuCAP 2014), Apr.

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Saito, K., T. Imai, and Y. Okumura [2014c], “2GHz band MIMO channel properties in urban small
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frequencies for 5G systems,” European Wireless Conference, Oulu, Finland.

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Satake, M., J. Uemoto, T. Matsuoka, T. Kobayashi, S. Kojima, T. Umehara, and T. Moriyama[2015], “Polarimetric calibration of PI-SAR2: Experimental results of 2013 to 2015 observations,”
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