Annual Report

Hydrospheric Atmospheric Research Center(HyARC)
Nagoya University

2008

drospheric tmosphericesearch enter(HyARC)

2008
NAGOYA
UNIVERSITY

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Contents
Foreword

2

Staff and Organization

3

Research Programme

5

Progress Reports
Projects
Division of Regional – Scale Water Cycle Processes
Laboratory of Meteorology
Laboratory for Climate System StudyLaboratory for Cloud and Precipitation Climatology

Division of Global – Scale Water Cycle Variations
Laboratory of Satellite Meteorology
Laboratory of Eco-Hydrometeorology
Laboratory of Ocean Climate Biology
Laboratory of Bio-Physical Oceanography

List of Publications

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8
12
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18
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28
30
32

09.7.31 5:14:34 PMForeword
The Hydrospheric Atmospheric Research Center (HyARC) at Nagoya University
was established eight years ago to promote research on the global water cycle, one ofthe primary components of the Earth system. Research on the global water cycle
requires strong and extensive collaboration among science and application communities, and hence HyARC functions as an inter-university collaborative system, inmany ways unique in the world.
HyARC has initiated numerous projects and activities. Prominent among these is
the International Project Office of the Global Energy and Water Cycle Experiment(GEWEX) Asian Monsoon Experiment (GAME), led by Prof. T. Yasunari, and its
various follow-on projects. Additional work has been supported by the following:
Grants-in-Aid for Scientific Research; Core Research for Evolutional Science andTechnology (CREST) of the Japan Science and Technology Corporation (JST); Global Environment Research Fund; Innovative Program of Climate Change Projection
for the 21st Century; and more. In addition, funding from the Ministry of Education,
Culture, Sports, Science and Technology, Japan, supported construction of a multiparameter radar system to study water circulation, and funding from the InterUniversity Project supported a virtual laboratory for study of the earth’s climate
diagnostics.
HyARC has also collaborated with numerous institutions, such as the ResearchInstitute of Humanity and Nature (RIHN) and the National Institute of Information
and Communication Technology (NICT). As partial contribution to the UNESCO
International Hydrology Programme (IHP), HyARC has conducted training courses,
funded by the Japan Trust; this year’s course was on satellite remote sensing of
atmospheric constituents.
In selecting projects and activities, HyARC considers project feasibility, significance,and collaboration requirements. We currently fund four research center projects andone workshop. Although HyARC’s permanent staff numbers only 11 (4 professors, 4associate professors, and 3 assistant professors), we also support many postdoctoralcandidates in active research. In addition, we have accepted graduate students in the
Department of Environmental Studies.
Nagoya University has adopted a flexible management system that emphasizes
accountability yet encourages research publications and outreach programs. Accordingly, and spurred by comments from an outside evaluation committee, we herewith
propose to establish a large-scale national/international facility, and a new organization to address its social requirements.

Uyeda Hiroshi
Director
Hydrospheric Atmospheric Research Center

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Staff and Organization
Division of Regional – Scale Water Cycle Processes

Research
Division

Professor
Assoc. Prof.

UYEDA Hiroshi
YASUNARI Tetsuzo
TSUBOKI Kazuhisa
MASUNAGA Hirohiko

Assist. Prof.

SHINODA Taro
FUJINAMI Hatsuki

OHIGASHI Tadayasu(Designated Assist. Prof.)

Division of Global – Scale Water Cycle Variations

Board ofCouncilors

Professor
Assoc. Prof.

NAKAMURA Kenji
HIYAMA Tetsuya
MORIMOTO Akihiko

Assist. Prof.

MINO Yoshihisa

Sandric C.Y. LEONG(Designated Assoc. Prof.)

Director
Common Section

Advisory
Board

Administrative

OfficeTechnical
OfficeMINDA Haruya(Technical Center)

Secretary
OfficeTOIDA Machiko

Administrative

Director

SATO Shigeaki

General Affairs
SectionAccounting
Section

ISHIKAWA Yoshinori
MIYAKE Takaaki
ISHIHARA Hidenori
NISHIKAWA Sachi

Supplies
SectionMIYANO Koji
MANABE Ken
NISHIKAWA Kasumi

Student Affairs
Section01-1.HyARC2008-E.indd 3

YOKOI Masao
TAKAGI Kenichi
SAHASHI Miki

KAWAI Akira
ONO Yoko
OYA Yumiko

09.7.31 5:14:34 PMAdministration
Board of Councilors

UYEDA Hiroshi: Director, Prof., Hydrospheric Atmospheric Research Center
YASUNARI Tetsuzo: Prof., Hydrospheric Atmospheric Research Center
NAKAMURA Kenji: Prof., Hydrospheric Atmospheric Research Center
TANAKA Kentaro: Prof., Graduate School of Science
TSUJIMOTO Tetsuro: Prof., Graduate School of Engineering
HATTORI Shigeaki: Prof., Graduate School of Bioagricultural Sciences
Kanzawa Hiroshi: Prof., Graduate School of Environmentral Studies
FUJII Ryoichi: Prof., Solar-Terrestrial Environment Laboratory

Advisory Boardl Members from Nagoya Unisversity

UYEDA Hiroshi: Director, Prof., Hydrospheric Atmosphric Research Center
YASUNARI Tetsuzo: Prof., Hydrospheric Atmospheric Research Center
NAKAMURA Kenji: Prof., Hydrospheric Atmosphric Research Center
TSUBOKI Kazuhisa: Assoc. Prof., Hydrospheric Atmosphric Research Center
MASUNAGA Hirohiko: Assoc. Prof., Hydrospheric Atmosphric Research Center
HIYAMA Tetsuya: Assoc. Prof., Hydrospheric Atmosphric Research Center
MORIMOTO Akihiko: Assoc. Prof., Hydrospheric Atmosphric Research Center
MIZUTANI Norimi: Prof., Graduate School of Engineering
OHTA Takeshi: Prof., Graduate School of Bioagricultural Sciences
YAMAGUCHI Yasushi: Prof., Graduate School of Environment Studies
MATSUMI Yutaka: Prof., Solar-Terrestrial Environment Laboratoryl Members outside Nagoya University

FUJIYOSHI Yasushi: Prof., Institute of Low Temparature Science, Hokkaido University
HANAWA Kimio: Prof., Graduate School of Science, Tohoku University
SUMI Akimasa: Prof., Integrated Research System for Sustainability Science, 		The University of Tokyo
FUKUSHIMA Yoshihiro: Prof., Tottori University of Environmental Studies
YAMANAKA Manabu: Senior Scientist, Institute of Observational Research for Global
Change, Japan Agency for Marine-Earth Science and Technology

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09.7.31 5:14:35 PMResearch Programme
Water circulation studies using new polarimetric radar
A new polarimetric (multi-parameter) radar was installed at the Hydrospheric Atmospheric Research Center (HyARC), Nagoya University, in 2007. Since installation, this equipment has been promoting new studies on clouds and precipitation, and aiding in the development of new observational and analytical techniques that are essential for studies on water
circulation. Such observational and analytical techniques, as well as data assimilation
methods, are necessary for the utilization of observational data from the new radar and for
amalgamation of the data with a cloud-resolving model.
This research plan aims at promoting new research on water circulation using the newpolarimetric radar as well as existing radar sets. In concrete terms, we examine andimplement observational data of weather phenomena and physical processes of cloud andprecipitation systems. We aim at developing new parameters for multi-parameter radarobservation and data analysis and new display methods for radar data. We will develop software and operational routines for the radar from physical and engineering viewpoints incollaboration with researchers participating in this study project.

Diurnal processes of convection/precipitation systems in the climate
systemDiurnal variations in convection and precipitation are prominent meteorological phenomena that occur particularly in tropic/subtropic and monsoon regions. Energy, water, andmomentum exchanges through the diurnal cycle occur among the Earth’s surface, atmospheric boundary layer, and free atmosphere, and play a crucial role in global climate. However, climate models such as a general circulation model (GCM) cannot produce realistic
diurnal convection/precipitation cycles, and they continue to exhibit systematic errors.
This research plan aims at clarifying the effects of regionality and seasonality on diurnal
processes, based on the Tropical Rainfall Measuring Mission (TRMM) satellite, other remotesensing data, and in situ observational data from rain-gauge stations. The plan also uses
cloud-resolving models such as CReSS and WRF model as well as other regional models to
elucidate systematic errors on the part of climate models in handling diurnal cycles. This
work can contribute to the ongoing international project MAHASRI and promote further
study of diurnal convection/precipitation cycles in the climate system in Japan.
On March 5-7, 2009, an international MAHASRI/HyARC workshop on Asian monsoons
was held in Danang, Vietnam. Studies on diurnal variations in cloud/precipitation systems,
taking into account terrain, synoptic conditions, intraseasonal variations, and more, were
presented. Ten speakers (including two keynote speakers) presented significant scientific results to over 70 workshop participants.

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09.7.31 5:14:35 PMGlobal Mapping of Variation in Terrestrial Water Storage
Not much is known about seasonal and climate-related variations in the distribution ofterrestrial water. Monthly gravity field estimates made by the twin Gravity Recovery andClimate Experiment (GRACE) satellites have a geoid height accuracy of 2 to 3 mm at a spatial
resolution of 400 km. If we could estimate distributions of monthly precipitable water andprecipitation, geoid variations could be largely attributed to surface water and groundwaterchanges. Thus, GRACE observations will help us connect processes at traditional length scales(tens of kilometers or less) to those at regional and global scales. In this research program,
we promote GRACE-related research with a focus on global mapping of terrestrial water storage.
HyARC is also conducting mass spectral analyses of stable isotope ratios of water. Stable
isotope ratios of water (δD & δ18O) and anomalies from the well-known meteoric water line
(d-excess = δD – 8 · δ18O) are good indicators of the origins of precipitation, river water, groundwater, and so on. Because isotope ratios of water are controlled by kinetic or equilibrium
fractionation processes in evaporation or condensation, the ratios can be used for evaluating
global water cycles as supporting tools for water balance calculation, paleoclimate variation
research, and basin-scale hydrological studies. In fiscal 2008, we comprehensively analyzed
2400 water samples upon requests from six domestic researchers.
This research plan also aims to promote studies in terrestrial water storage as well as
isotope hydrology, and to link those research activities among several research groups inJapan. We have conducted an annual science workshop related to this research plan. In fiscal
2008, we held a workshop from February 26 to 27, 2009. A total of 37 participants attended
the workshop, and valuable discussions were held on the issues described above.

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
Observational study on atmosphere and ocean over and around the
Okinawa Islands
The National Institute of Information and Communication Technology (NICT) establishedan observation center in Okinawa. Center facilities include a full polarimetric Doppler radar(COBRA), 400-MHz wind profiler radar, Doppler sodar, disdrometers, rain gauges, and ocean
radars. Collaboration between NICT Okinawa and HyARC began in 2005, and use of the facility was encouraged as one of the inter-university collaboration activities of HyARC.
During the last three years, the collaborative has produced many study results and havepresented in annual project workshops. Study results include better understanding of thefollowing: spatial and temporal variations in the Kuroshio Current around the Okinawa Islands
observed by ocean radar; raindrop size distribution characteristics, determined by COBRA
polarimetric data; and characteristics of atmospheric low-level jets over Okinawa Main Island,
determined by wind profiler data. These study results suggest the possibilities and also thelimitations of observations using the NICT Okinawa facility. An advantage is that long-term
data have been accumulated, enabling the study of ocean and atmosphere climatology aroundthe Okinawa Islands. A limitation is the observation range of ocean radars is short for the
study of spatial variations in the Kuroshio Current around the islands, although synergy withother data such as satellite data mitigates this particular limitation.
In the fiscal year of 2008, this project was restarted under a new Japanese title with a newemphasis on climate. Studies are mainly extensions of previous ones, but new ideas and proposals for the facility have appeared. In addition, the center’s infrastructure has been improved,with upgrades to instruments, high-speed communication lines, and more. All of this suggeststhat the NICT Okinawa facility is now ready to be put to extensive use.

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09.7.31 5:14:35 PMProgress Reports
Projects
The Innovative Program of Climate Change Projection for the 21st Century(KAKUSHIN Program)l Cloud Modeling and Typhoon Research

The Innovative Program of Climate Change Projection for the 21st Century (KAKUSHIN
Program) is a research program conducted by the Ministry of Education, Culture, Sports,
Science, and Technology (MEXT). KAKUSHIN was started in 2007 and will continue for five
years. As a part of the program, a research project named “Cloud modeling and typhoon
research” is now underway at HyARC (PI: K. Tsuboki) to develop a high-resolution cloudresolving model and to contribute to the accurate projection of future climate by global
models. In the second year of the program, our team has been obtaining some research
results.
Cloud physics is one of the key processes in modeling studies of climate change, especially studies of global warming. Improvement of the computational scheme of the cloud
processes is necessary for accurate simulations in global models. Cloud processes are also
core processes in simulations of high-impact weather systems such as heavy rainfalls andtyphoons. The following are the four main objectives of the cloud modeling team. (1) Cloud
microphysics in the cloud-resolving model Cloud Resolving Storm Simulator (CReSS) will be
improved. The dynamic part of the CReSS model will also be improved for accurate and highspeed calculation. (2) Using the CReSS model, cloud parameters of global models will be
examined. Satellite observations are used to verify cloud modeling. (3) CReSS is coupled with
global models interactively for accurate modeling of convective regions. In particular, convective clouds in the tropical region and typhoons are studied by the modeling system. (4) The
CReSS model is also used for typhoon research. The results are used to verifications of typhoon
simulations in global models, and to accurate and quantitative evaluations of the impact of
typhoons on human society in the present and warming climates.
Regarding the improvement of the microphysical processes of the CReSS model, theprocess of ice nucleation was examined and improved this year. The sedimentation processof ice particles and the ice-enhancement process were introduced and tested. Without ice
enhancement, ice particles are concentrated at the tops of clouds. The enhancement processincreases the number concentration just above the melting layer. A large amount of ice wasobserved just above the melting layer by sounding observations with a hydrometeor-camera.
Using the observation data, we verified the results of simulations. To improve the dynamicalpart of CReSS, we introduced a semi-Lagrangian scheme and made a test simulation of anobserved cold front. The scheme increases the integration speed significantly.
This year, we made daily simulation experiments in the regions of the East China Sea and
Palau in the tropics with a horizontal resolution of 4 km. Daily simulations with a horizontal
resolution of 1 km were also performed in the Tokai and Hokuriku Districts. These experiments produced a large amount of data on clouds and precipitation.
For the evaluation of CReSS to perform a typhoon simulation, we performed a 14-day
simulation of Typhoons 16 and 18 of 2004 using the tiling domain technique. The simulated
central minimum pressure of Typhoon 18 reached that of the observed typhoon. The simulated rainfall distribution was verified by JMA (the Japan Meteorological Agency) radarAMeDAS observation. Figure 1 shows that the simulated rainfall distribution around the
Kyushu District at 13 days from the initial time is quantitatively similar to the observed rainfall. This indicates that CReSS is useful for typhoon simulations.

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
The Meteorological Research Institute of JMA simulated the present and global warming
climates using a very high-resolution global circulation model (GCM) as part of the KAKUSHIN
program. We found very intense typhoons in the model outputs of the GCM and performed
cloud-resolving simulations of the typhoons using CReSS. The comparison of the central
minimum pressure in GCM and CReSS simulations showed that some typhoons are verymuch more intense in CReSS than in GCM, whereas others are weak. The correlation of typhoon intensity between GCM and CReSS is very weak. The maximum velocity around thetyphoons is usually larger in CReSS than in GCM. In the warming climate simulation, we
found super-typhoons, which have an intense maximum sustained wind speed of 67 m/s orgreater. No super-typhoon was found in the present climate simulation, suggesting that global warming results in the intensification of typhoons.

Figure 1. Comparison of rainfall distributions of Typhoon 18 at 13 days from the initial time.
Left panel shows the CreSS simulation using the tiling domain technique; right panel shows JMA radarAMeDAS observations. The center of Typhoon 18 is located west of Nagasaki Prefecture. The contours
in the left panel are surface pressure, and the arrows are horizontal wind velocity.

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10Study consortium for Earth-Life Interactive System (SELIS)The Study consortiumu for Earth-Life Interactive System (SELIS) was established as a
virtual institute in Nagoya University in March 2008, to follow up the research activity of the
21st century COE Program of “the Sun-Earth-Life Interactive System”. The member instateof SELIS are HyARC, Graduate School of Environmental Sciences (GSES), Graduate Schoolof Bio-Agricultural Sciences (GSBS) and the Solar-Terrestrial Environmental Laboratory. The
SELIS project office is located at the 5th floor of the Institute for Advanced Research Hall of
this campus, and the HyARC is managing this office as a main institute of SELIS. The main
objective of the SELIS is to promote coopearative studies and relevant capacity building for
the Earth-Life Interaction studies, and to promote collaboration with relevant national andinternational programs and projects. SELIS is also expected to contribute to research projects
proposed from Nagoya University to the Research Institute for Humanity and Nature (RIHN)
in Kyoto. In the education program, SELIS contributes to some lecture course and seminars,
e.g., “Chikyu-gaku” (Study for the Earth) at the GSES.
The kick-off meeting and seminar was held on June 3 2008, and we had eight SELIS
seminars in the 2008 school year. In addition, we organized the special lecture in December
1, 2008, on “Current status of global warming research” by Prof. Shukuro Manabe, who iscurrently a distinguished invited professor. SELIS also organized the 1st SELIS international
scientific workshop in January 2009 on “Eco-Climate Dynamics in Monsoon Asia and Eurasia”,
where five leading scientists for this field were invited from USA, Europe and China.

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11Solution Oriented Research in Science and Technology (SORST)
l Satellite Monitoring of Ocean Primary Productivity

The ocean is the largest reservoir of water and carbon dioxide on the Earth’s surface;hence, the air-sea exchange of water and carbon dioxide plays a central role in determining
climate systems on the Earth. The air-sea exchange of heat (water) and carbon dioxide is affected by phytoplankton because they determine the optical properties of the near-surface
oceans and absorb carbon dioxide by primary productivity. To better predict climate variability by mechanistic understanding of regulating processes for phytoplankton and improved
climate prediction models, global-scale quantitative knowledge of the abundance and productivity of phytoplankton is required. Practically, this knowledge and understanding will beattained only by satellite observations, but because obtaining in situ data for validation ofsatellite data is difficult, the satellite data have yet to be fully exploited.
To overcome this difficulty, we have been developing a system for in situ monitoring ofocean primary productivity for validation of satellite data. The system, which is composed ofan underwater winch system with a profiler buoy equipped with a fast repetition rate fluorometer, was successfully developed with support from Core Research for Evolutional Scienceand Technology of the Japan Science and Technology Agency (JST). Following this, a continuation project “Satellite Monitoring of Ocean Primary Productivity” (SMOPP) was approvedby JST in the Solution Oriented Research in Science and Technology Program in 2004. The
goal of the SMOPP project is to design an operational monitoring system for ocean primary
productivity on a global scale. To attain this goal, we conduct routine operation of the monitoring system and obtain validated time series satellite data of primary productivity, which
will be used in combination with other time series satellite data on physical forcing parameters on the ocean surface, for process studies on the response of ocean biology to atmospheric forcing of the ocean.
Long-term operation of the monitoring system in Sagami Bay has been carried out since2007 and we were able to operate the monitoring system successfully from November 2007
to November 2008, although it was recovered temporarily for maintenance. As a result, daily
vertical profiles of ocean productivity as well as hydrographic parameters, which could not
be obtained by ship observations, were derived. To validate the satellite-based process study
and reveal temporal and spatial variation in physical and biological phenomena in Sagami
Bay, we conducted hydrographic observations four times in the bay. FY 2008 research activities in the SMOPP project are described separately in the activity reports of the Ocean
Climate Biology Lab and Bio-physical Oceanography Lab. As for the Primary Productivity
Profiler, we continued efforts to conduct as many measurements as possible in various environments such as the northern North Pacific, East China Sea, and Japan Sea. These data arearchived in the database after quality control. Since the SMOPP will be completed by next
October, we are analyzing huge amounts of data derived under the SMOPP and are finalizing
the findings.

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12 Division of Regional – Scale Water Cycle Processes
Laboratory of Meteorology
Structure of a precipitation system around Aichi Prefecture, Japan on August 28–29, 2008
A precipitation system brought heavy rainfall
around Aichi Prefecture on August 28–29, 2008.
Total rainfall amounts on these two days were
304.5 mm at Okazaki, 240.0 mm at Ichinomiya,and 202.0 mm at Nagoya. Hourly rainfall amounted to 146.5 mm at Okazaki from 01 to 02 Japan
Standard Time (JST) on August 29. In this study,
we examine the structure of the precipitation
system using a new X-band polarimetric radarsituated at Nagoya University and the Cloud Resolving Storm Simulator (CReSS).
Fig. 1. Vertical cross section of distributions of reFrom observations using the polarimetricflectivity (contour) and Doppler velocity
radar, a line-shaped precipitation system aligned(shades) in the Range Height Indicator (RHI)
from south-southwest to north-northeast propaalong the direction of 316.08° from thegates southeastward slowly (at about 7 m/s).
polarimetric radar situated at Nagoya UniSoutheastern and northwestern regions of theversity at 22 : 23 JST on August 28, 2008.
Light and dark shades show southeasterly
precipitation system in the lower tropospherewind (away from the radar) and northwestare occupied by southeasterly and northwesterly wind (approaching the radar), respecerly winds, respectively; thus, the low-level contively.
vergence between these low-level winds should
maintain the precipitation system (Fig. 1). The
differential reflectivity (ZDR) observed by the polarimetric radar shows the existence of largeraindrops whose median volume diameter (D0)is greater than 2.7 mm. The observation of theground-based drop size distribution (DSD) using
the Disdrometer also shows the existence of largeraindrops whose D0 is greater than 2.3 mm; thus,
many large raindrops were formed in the precipitation system and should contribute to theheavy rainfall.
Global Spectral Model (GSM) data provided
by the Japan Meteorological Agency (JMA) areused as the initial and boundary conditions of asimulation with a horizontal grid resolution of
2 km using the CReSS. The simulation reproduces well the generation location, propagation
direction, and speed of the precipitation system;and the maximum hourly precipitation amount Fig. 2. Simulated horizontal distribution of hourly
precipitation amount (mm: shade) from 22 :around Aichi Prefecture (Fig. 2). The simulation
00 to 23 : 00. Barbs are horizontal wind vecalso reproduces the low-level convergence betors at the surface at 23 : 00 JST. Cross andtween the southeasterly and northerly winds
solid circle show the location of the polaribelow the precipitation system (Fig. 3). The
metric radar and observation range (64 km),southeasterly is a high equivalent potential temrespectively.
perature (warm and moist) airmass induced bya synoptic-scale situation. On the other hand, the northerly is a relatively low equivalent potential temperature airmass, whose relative humidity is greater than 75%, induced by thedowndraft in the precipitation system. Since evaporation cooling is quite limited in a moist
environment, the temperature decrease at the surface is only about 2 or 3°C. Although the
propagation of the precipitation system shows a gravity-current-like structure by the relatively cool and dry airmass located on the northwestern side of the system, the propagation

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13speed to the southeastward is slow, because the difference in density of the airmasses between
both sides is quite less. The minute effect of evaporation cooling in the precipitation systemis the predominant structure under the high humid environment.

Fig. 3. Simulated vertical cross section of distributions of equivalent potential temperature(shade), estimated reflectivity from mixing
ratio of precipitation (rain, snow, and graupel: contour), and wind vectors shown by
horizontal wind along the plane and verticalwind (arrows) along the southeast-northwest
direction at 23 : 00 JST. Nagoya University is
located at the origin (O).

Formation and maintenance processes of the heavy rainfall event around Fukui Prefecture
simulated by the CReSS
A heavy rainfall event was observed aroundnorthern Fukui Prefecture on July 18, 2004. The
heavy rainfall event is called the Fukui Heavy
Rainfall. The event is divided into two stages:
the first and second stages are from 01 to 03 andfrom 05 to 12 JST based on data from the Radar–AMeDAS operated by the JMA. A line-shaped
precipitation system is observed initially andchanges to an oval-shaped one around 07 JST
when the maximum precipitation amount is reFig. 4. Horizontal distributions of 3-hourly accucorded around Fukui Prefecture.
mulated rainfall amounts around Fukui PreTo reproduce the precipitation system, a simfecture between 07 and 10 JST of Radar–ulation with a horizontal grid resolution of 1 km
AMeDAS (a) and the simulation (b).
is conducted using the CReSS. The simulation
starts at 03 JST on July 18. The simulation reproduces well the distribution and amount of 3-hourly precipitation compared with the Radar–AMeDAS observations (Fig. 4). The maximum precipitation amount, exceeding 50 mm hr−1, around
Fukui Prefecture and its time series are also reproduced (Fig. 5). Using the simulation result,the formation and maintenance processes of the
precipitation system are examined. Sensitivity
tests with modified topography and without evapFig. 5. (a) AMeDAS observation sites in northern
oration of rain are also conducted to clarify the
Fukui Prefecture (▲) and the region inmaintenance process.
which the maximum hourly rainfall amountThe precipitation system is generated aroundis calculated in the simulation result (rectthe Oki Islands where high convective unstable
angle). (b) Time series of maximum hourly
stratification and a weak low-level convergence
rainfall amount observed by AMeDAS (barappear using JMA regional objective analysis
graph) and simulated by the CReSS (solidline) enclosed in the rectangle in (a).
(RANAL) data and the simulation result; thus, aconvective precipitation system would be easily
generated. The system propagates eastward over the Sea of Japan after its generation aroundthere. A westerly wind in the lower troposphere supplies a high equivalent potential temperature airmass that maintains the precipitation system. The system only flows eastward

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14
due to westerly winds in the middle troposphere and does not show the back-building (BB)structure. When the precipitation system reaches Fukui Prefecture, the convergence zone in
the lower troposphere is maintained for about one hour. The convergence zone would bemaintained by the effects of mountains located along the coastal region of Fukui Prefecture,
based on the result of the sensitivity experiment. As a result, new precipitation cells develop
over the western tip of the lower convergence zone, i.e., in the upstream (western) side of thepre-existing cells that propagate eastward; thus, this is the BB structure. As the structure of
the precipitation system changes to the BB type, precipitation cells intrude continuously over
Fukui Prefecture, producing a large amount of rainfall there.

Structure of a developing typhoon simulated by the cloud-resolving model
A warm core and an eyewall cloud are characteristic structures of a typhoon. Numericalsimulations using the CReSS with a high horizontal grid resolution are conducted to clarify
the structure of the inner region of typhoon T0712. The purpose of this study is to clarify thecontribution of the warm core to the development of the typhoon, the origin of the airmassof the warm core, and the structure of the forces that act on the airmass in the inner regionof the typhoon.
The simulation reproduces well the track and pressure drop of the typhoon. The typicalstructures of the typhoon such as the warm core and eyewall clouds, and dynamical characteristics such as low-level inflow, updraft in the eyewall clouds and upper-level outflow in thetyphoon, are also simulated successfully. A warm core with a large positive anomaly of potential temperature (greater than 14 K) is generated at a height of about 15 km after 24 h fromthe initial time (Fig. 6). The positive anomaly of potential temperature contributes to an increase in thickness between 200 and 100 hPa. Although the height of 50 hPa is almost constantwith time, the increase in thickness around these levels contributes to the height of 900 hPa;thus, the pressure drops in the lower troposphere around the center of the typhoon.
A back-trajectory analysis is conducted to show the origin of the airmass in the warm core(Fig. 6). The origin of this airmass is divided into two regions. One moves inward in thelower troposphere and ascends in the eyewall clouds, and the other descends from the lower
stratosphere. Figure 7 shows time series of potential temperature and equivalent potential
temperature of the airmass coming from the lower troposphere. Potential temperature increases greatly between 18 and 20 h after thesimulation starts, when the airmass ascends inthe eyewall cloud; thus, the airmass should experience diabatic heating. Consequently, one ofthe origins of the warm core should be diabatic
heating in the eyewall clouds.
A forward trajectory analysis is also performed to investigate the dynamical processfrom the lower troposphere. The analysis showsthat most airmass flows outward in the upper
troposphere, and only a small amount moves
into the warm core. Although the pressure-gradient force mainly acts on the low-level inflow, thecentrifugal force is greater than the pressuregradient force around the inner side of the eyewall in the lower troposphere, where the radial
velocity changes from inward to outward. Thus,
it produces the low-level convergence below the
eyewall clouds and tilts the updrafts in them in Fig. 6. Radius-height cross section of azimuthally
the outward direction. This mechanism is comaveraged potential temperature anomaly at
the center of the simulated typhoon (dashedmon to both outward flow in the upper tropoline) after 24 h from the initial time. Solid
sphere and motion into the warm core. Most oflines show parts of the back trajectories. ▲the airmass is accelerated outward by the censhow the starting points of the back trajectrifugal force in the upper troposphere; on the
tory analysis.

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15other hand, only a small amount of airmass in which the pressure-gradient force is greaterthan the centrifugal force drifts into the warm core.

Fig. 7. (a) Radius-height cross sectionof one back trajectory analysis
from the lower troposphere.
(b) Time series of potential
temperature (solid line) andequivalent potential temperature (dotted line) of the airmass
along the trajectory in (a).

Tiling Domain Technique for a Cloud-Resolving Model
The computational domain of most regional models is generally rectangular. However,
the region of interest is not always rectangular but is often irregularly shaped. An arbitraryshaped domain is more suitable for efficient computation of simulations. In the present study,
we have developed a new technique to perform parallel computation of a cloud-resolving
model in an arbitrary-shaped region, which is named the Tiling Domain Technique (TDT),
for the CReSS model.
The arbitrary-shaped domain of parallel computation using the TDT is composed of manysmall rectangular domains called “domain tiles.” If a side of a domain tile is connected to aneighboring domain tile, a halo region is set along the side and data exchange is performed
with the neighboring tile by Message-Passing Interface (MPI). If no neighboring domain tile
is present, the side is considered a boundary of the computational domain. Each domain tile
is further divided into subdomains if necessary. Another parallel computation between subdomains within the domain tile is performed using MPI. The TDT performs these two typesof data exchange at different levels. We refer to this type of parallel computation as “hierarchical parallel computations.” Multiple computational domains consisting of different numbers of domain tiles in each domain are possible, as well as an isolated domain.
Using the TDT, we perform a simulation experiment of typhoon 0418 (T0418), which caused
severe damage all over Japan owing to strong
winds. In the experiment, 64 domain tiles areused along the track of T0418, and a one-weeksimulation is performed. The RANAL data of the
JMA are used for initial and boundary conditions. The horizontal grid size is 2000 m, and theexperiment is started from the initial conditionsof 00 UTC September 1, 2004. The central pressure of the simulated typhoon decreases rapidly
and reaches that of the best-track data after
about 3 days from the initial time. The simulated typhoon almost follows the JMA best track
Fig. 8. Comparison of simulations of the typhoonfor the 7 days of the simulation period. Figure 80418 in September 2004 using the tilingshows the comparison of simulations of thedomain technique (a) and all domain (b) at
T0418 using the TDT and all domain at the 6
6 days (518400 seconds) from the initialdays from the initial time. The TDT result of thetime. The gray levels are precipitation intendistribution of precipitation amount corresponds
sity (mm/h) and contour lines are sea-levelto that using the all domain. The corners of thepressure. The arrows are horizontal windvector at the surface. The solid line is the
TDT result do not affect the simulation result
best track of the typhoon 0418 provided bycompared with that using the all domain. When
the JMA.
the simulated typhoon approaches western

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16
Japan, it causes heavy rainfall over the land. The distribution and intensity of the simulated
rainfall correspond well to the observed rainfall.
Because a typhoon moves along a long curved track, the TDT is an efficient method forhigh-resolution simulation of the typhoon. Domain tiles are set along the typhoon track, andtotal computational cost is reduced. The TDT increases the flexibility and applicability of thecloud-resolving model for many different types of weather systems. For example, a computational domain is set along the Japanese Islands, and isolated domain titles are set in theregion of individual islands. Another possible application is convective activity in the tropicalregions, where the nonhydrostatic effect is crucial. A nested simulation in global circulation
model (GCM) using the TDT will be also useful for dynamical downscaling of typhoons.

Development of a three-dimensional detection algorithm for precipitation cells in East Asia
during the Meiyu/Baiu period
A precipitation cell is a fundamental elementof precipitation systems. To clarify the generalfeatures of precipitation cells, statistical analyses
are needed. In this study, a three-dimensional detection algorithm for precipitation cells has beendeveloped. Figure 9 shows the definition of precipitation cells using reflectivity data. The central
parts of the precipitation cells are recognized byconnecting negative regions of the second derivative for three-dimensional reflectivity data. After
connecting the central parts of precipitation cells
vertically, the three-dimensional region of eachcell is fixed.
The 811 precipitation cells obtained by Doppler radar in three observation projects conducted in East Asia during the Meiyu/Baiu period are
detected by human eyes to validate the algorithm.
More than 98% of precipitation cells are detectedusing the algorithm on the same observation data. Thus, the algorithm would have sufficient accuracy and would be reliable for statistical analyses of precipitation cells.
The algorithm can also detect “updraft cells”
and “downdraft cells” to apply three-dimensional
wind field data calculated from dual-Doppler
analyses. Matching up the precipitation cells with
updraft and downdraft cells marks the developing,mature, and decaying stages in their life-cycle.
Figure 10 shows a schematic illustration of discriminating the stages of precipitation cells. To
verify the discrimination, two precipitation cells
that were observed in the dual-Doppler region
through almost all of their life-cycle are chased,
and stages in their life-cycle are discriminatedbased on wind fields by human eyes. The algorithm’s results are consistent with those from human eyes.
The discrimination of stages is conducted using dual-Doppler analyses around Miyako Island(the Southwest Islands of Japan) during the Baiu
period in 2006. Precipitation cells in the developing, mature, and decaying stages are detected01-1.HyARC2008-E.indd 16

Fig. 9. Definition of precipitation cells using reflectivity data.

Fig. 10. Schematic illustration of discriminating
the stages of precipitation cells.

09.7.31 5:14:49 PM

17(183, 154, and 124, respectively). The volume of precipitation cells in the mature stage isgreater than at other stages. Although the echo top height of precipitation cells in each stageis almost constant through their life-cycle, the area of precipitation cells in the mature stageis almost twice that at other stages. As a result, the volume of precipitation cells in each stage
should depend on their area.

Development of a cumulus boundary layer over land
Development of a cumulus boundary layerover land is investigated using idealized highresolution numerical simulations with the focus
on the onset of “active cumulus” and the effectof external factors: initial amount of water vapor, static stability, and surface energy partition.
A simulation with a horizontal grid resolution of 100 m is conducted using the CReSS.
The parameters of idealized initial profile andland surface are set using observational dataobtained in the Huaihe River Basin in China
on June 20, 2004. Land surface is set to water
paddy fields, which are characterized by large
latent and small sensible heat fluxes. In the control experiment, the cumulus boundary layer Fig. 11. (a) Time-height cross section of cloud fraction (shade) and time series of lifting conexperiences transition from a condition indensation level (LCL: solid line), LFC (browhich only forced cumulus exists (forced cuken line), and level of neutral buoyancy
mulus boundary layer) to a condition in which(LNB: dotted line) calculated from mean
active cumulus also exist (active cumulus
values at a height of 45 m (lowest level ofboundary layer) at about 1220 local standard
model domain). (b) Same as (a) but for meantime (LST). The active cumulus onset is almost
relative humidity (shade) with mean virtual
coincident with an abrupt drop in the level ofpotential temperature (contours, every 1
K).
free convection (LFC: Fig. 11). The LFC dropis attributed to a decrease in the local minimum
value of saturated equivalent potential temperature at the bottom height of the inversion
layer, in addition to an increase of equivalentpotential temperature near the land surface(Fig. 12). After the active cumulus onset, theinversion height maintains a large rate of increase because evaporation of cloud water cools
and moistens the inversion layer.
Systematic sensitivity experiments showthat the onset time arrives earlier with greater Fig. 12. Profiles of mean equivalent potential teminitial water vapor, smaller static stability, andperature (solid lines) and saturated equivagreater evaporative efficiency through changes
lent potential temperature (broken lines) atin the time tendency of saturated equivalent
11 LST (a) and 13 LST (b). Dotted lines indicate the mean equivalent potential tempotential temperature at the bottom height ofperature of air near the land surface (at athe inversion layer and equivalent potential
height of 45 m).
temperature near the land surface. Since thedevelopment of the active cumulus boundary
layer causes a large rate of increase of the inversion height, an earlier active cumulus onset
leads to a higher inversion height. As a result, water vapor does not accumulate in the lower
troposphere and is transported up to the inversion layer; thus, it contributes to the development of a deep moist layer. Therefore, this study demonstrates the interaction between featuresof the atmospheric environment, such as initial water vapor profile and static stability, andshallow cumulus clouds.

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18Laboratory for Climate System Study
Intraseasonal Variability of the East Asian Summer Monsoon
The mei-yu–baiu front is an important cloud and precipitation system of the East Asianmonsoon, providing large amounts of precipitation in early summer (Fig. 1). The front forms
as a subtropical front under the influence of atmospheric circulation in the midlatitudes andsubtropical/tropical monsoon regions. The mei-yu front includes both tropical and extratropical variations because of its geographical location. Therefore, tropical and extratropicalinteractions are an inherent property of the variation. During boreal summer, midlatitude
systems that vary on submonthly (7–25 days) time scales favorably propagate along the Asian
westerly jet. Thus, a close relationship between midlatitude systems and mei-yu variability inearly summer could be expected. Based on submonthly convective fluctuations over the Yangtze and Huaihe river basins (YHRBs) during the mei-yu season (June 10–July 10), we examined
the spatiotemporal evolution of convection and circulation over East Asia, focusing on therelationship between upper-level atmospheric circulation in the midlatitudes and convection
over the YHRBs. Data used in this study are outgoing longwave radiation (OLR) and National Centers for Environmental Prediction/ National Center for Atmospheric Research reanalysis data for the period between 1979 and 2004. 7- to 25-day filtered OLR anomalies averaged over the key region (25–35°N, 110–120°E) were used as indices to study submonthly
variation over the YHRBs.

Fig. 1: Mean OLR (shading), 700-hPa stream function,
and wind vectors for the mei-yu period (June
10–July 10; 1979–2004). The topographic contour line for 1500 m is also shown (thick dashedline). The key convective variation region is enclosed by the 25–35°N, 110–120°E grid box.

Fig. 2: (a) Time series of detrended OLR anomalies(dashed line), 7- to 25-day filtered anomalies(solid line), and unfiltered precipitation (blackbar) averaged over the key region for 1992.
(b) The local wavelet spectrum of the detrended
1992 OLR anomalies. The thick solid (dotted)
contour line encloses regions of 95% (90%)
confidence for a red noise process with a lag-1
coefficient.

7- to 25-day OLR variance averaged over the key region shows large interannual variation
over the key region during the mei-yu period. We scrutinized active submonthly intraseasonal oscillation (SISO) years (12 years: 1981, 1985, 1986, 1989, 1992, 1993, 1995, 2000, 2001,
2002, 2003, and 2004). In years of suppressed SISO, we found ISOs of approximately 30 days
(e.g., 1988, 1991, 1994, and 1998) and less remarkable ISOs of both submonthly and longer

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19time scales (e.g., 1980, 1983, 1987, and 1996). Figure 2 shows time series of OLR anomalies
and precipitation in 1992. The 1992 OLR anomalies have quasi-periodic oscillation with three
active convection phases during the mei-yu period (Fig. 2a). The active phases include heavy
and continuous precipitation (10–20 mm/day). The wavelet spectrum shows a statisticallysignificant peak with a period of approximately 7–12 days during the mei-yu period (Fig. 2b).
Remarkable submonthly-scale ISOs can be observed during the mei-yu period in the otheryears analyzed.
To examine the relationship between convection over the YHRBs and upper-level atmospheric circulation, correlation coefficients between OLR anomalies over the key region and
200-hPa streamfunction anomalies in each grid in the 7- to 25-day bands are shown in Fig.
3. Correlation distribution shows two contrasting patterns, suggesting that the dominant
processes inducing SISO in mei-yu activity are different, even though they have the same
submonthly time scales. Figure 3a shows that large values extend from the northern to eastern peripheries of the Tibetan Plateau (hereafter defined as the NET pattern). Active (suppressed) convections over the YHRBs are associated with an anomalous trough (ridge) to thenorth of the YHRBs and an anomalous ridge (trough) to the south of the YHRBs in the upper
troposphere. In contrast, in Fig. 3b, high correlation coefficients appear along approximately
30°N across the Tibetan Plateau with a wave-train-like distribution (hereafter defined as theAT pattern); the entire key region has negative correlations. Active (suppressed) convections
over the YHRBs are associated with the upper-level anomalous ridge (trough).

Fig. 3: (a) Correlation coefficients between 7- to 25-day filtered OLR anomalies over the key region and 200-hPa
stream function anomalies in every grid in the 7- to 25-day bands for 1981, 1985, 1989, 1992, and 2004.
The contour interval is 0.1. (b) As in (a), but for 1986, 1993, 1995, 2001, and 2003.

Composite analysis of the NET pattern shows slow southward migration of convection
anomalies from the northeastern periphery of the Tibetan Plateau to southern China, in relation to southward migration of the mei-yu front caused by simultaneous amplification of
upper- and low-level waves north of the YHRBs. In the AT pattern, convection anomalies
migrate eastward from the western Tibetan Plateau to the YHRBs. A low-level vortex is created at the lee of the plateau by eastward moving upper-level wave packets and associatedconvection from the plateau.
Rossby wave trains along the Asian jet characterize upper-level circulation anomalies inthe two patterns. Basic state of the Asian jet during the mei-yu season differs between the twopatterns, especially around the Tibetan Plateau. The Asian jet has a northward arc-like structure in NET years, whereas a zonal jet dominates in AT years. These differences could alter
the Rossby wave-train propagation route. Furthermore, AT waves have a larger zonal wave-

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20
number (approximately 7–8) than NET waves (approximately 6), indicating a faster zonal
phase speed relative to the ground in the AT pattern than in the NET pattern. These differences likely explain meridional amplification of waves north of the YHRBs in the NET patternand eastward wave movement across the plateau in the AT pattern. (Fujinami and Yasunari
2009, Mon. Wea. Rev.)

Mechanism of the decreasing trend of monsoon rainfall in September over the Indochina Peninsula
We examined the decreasing trend in rainfall during the late summer monsoon season(September) in Thailand from 1951 to 2000 and associated changes in tropical cyclone (TC)
activity. Thailand receives significant rainfall from May to October and experiences 2 rainy
peaks in late May to early June and in September. A previous study reported a decreasing
trend in September rainfall in Thailand and, based on a regional climate model, suggested
that this trend was associated with local deforestation. However, the long-term trend may
also be affected by changes in large-scale circulation. Thus, we investigated changes in largescale circulation associated with the decreasing rainfall trend.
Westward-propagating TCs from the South China Sea and the western North Pacificbrought most of the rainfall over Thailand in September. TCs include tropical depressions,tropical storms, severe tropical storms, typhoons, and residual lows. Furthermore, 70% ofSeptember rainfall was estimated to be associated with TCs. The 50-year time series of September rainfall over Thailand showed a significant decreasing trend. TC activity, defined by
700-hPa relative vorticity, showed a weakening trend over the Indochina Peninsula (Fig. 4).

Fig. 4: Scatterplot of September rainfall over Thailand and TC days
defined by 700-hPa relative vorticity. Rectangle, circle, andstar symbols indicate the relationship in each year during
P1, P2, and P3, respectively. The crosses labeled P1, P2, andP3 show the mean relationship of each period. There werefewer samples for P1 than for the other 2 periods becauseof limitations of the ERA-40 dataset.

TC tracks also suggested weakening TC activity over this area (Fig. 5). The long-term trend
in rainfall during the late summer monsoon season was closely associated with changes in
TC activity over the Indochina Peninsula; these changes were probably caused by changes in
the major course of TCs. Concurrent with the changes in TC tracks, a change in the TC steering current occurred around the Philippine archipelago and Taiwan. This led to the TC activity over the Indochina Peninsula being inactive, probably resulting in the long-term decrease

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21
in rainfall over Thailand. (Takahashi and Yasunari, 2008, JMSJ)
To address the mechanism for the decrease in rainfall, we performed long-term simulations and discussed the effects of long-term changes in both local surface conditions andlarge-scale circulation. Long-term high-resolution simulation accurately captured the climatological rainfall distribution and quantity. A 30-year run simulated the interannual variationand long-term change in rainfall, both of which were in close agreement with observations(Fig. 6). Spatial distribution of the long-term change in rainfall was also found to be in close
agreement with observations. A long-term decrease in rainfall was observed along the majorroute of westward-moving TCs, including the eastern coast of northern Vietnam, rather thanjust over Thailand. Finally, the simulated monsoon trough weakened from T1 to T2, which
again was consistent with observations. All these long-term changes in rainfall were realistically simulated without including the effects of deforestation in the model. The effects ofdeforestation over the Indochina Peninsula in September were probably spatially limited, andhence, are not likely to explain the observed decrease in rainfall. Weakening of TC activity
over and around the Indochina Peninsula could explain the spatial distribution of the observed
decrease in rainfall. Therefore, we conclude that the observed long-term decrease in September rainfall was caused by the change in TC activity, rather than by changes in local surface
conditions. (Takahashi et al. 2008, ASL)

Fig. 6: Time series of the observed September rainfall
10-point average (black) and the simulated September rainfall domain average (gray). The 10
Fig. 5: Japan Meteorological Agency (JMA) TC tracks instations were located within an area at 101–
September during P1, P2, and P3. Some tracks
105°E, 15–18°N. Simulated rainfall was domainstart from the midstream of a TC lifetime, whereaveraged within the box. The units of rainfall areas other tracks end in the midstream. Only TC
mm per month. The gray (black) dashed lines
tracks in September were plotted. JMA TC tracks
denote 15-year averages of simulated (observed)
do not include TCs weaker than a tropicalrainfall for each term.
storm.

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22
Loboratory for Cloud and Precipitation Climatology
The southeastern Pacific warm band and double intertropical convergence zones (ITCZ)
The intertropical convergence zone (ITCZ) over the east Pacific Ocean remains 5–10° in
latitude north of the equator most of the year. However, a southern-hemisphere branch of the
ITCZ also often emerges from March to April in the east Pacific, resulting in a double ITCZ.
We have no satisfactory explanation to date as to what promotes the double ITCZ in austral
fall and hampers it in boreal fall. This study is aimed at determining the growth mechanismof the east Pacific double ITCZ in austral fall.
Satellite measurements from the Tropical Rainfall Measuring Mission (TRMM) and
QuikSCAT are analyzed to derive 8-year climatologies of sea surface temperature (SST),
surface convergence, column water vapor (CWV), shallow and deep precipitating clouds, andsurface heat fluxes from 2000 to 2007. SST produces the initial signature of the south ITCZ,
referred to as the southeast Pacific warm band, as early as January. A pronounced feature of
the warm band is a local SST maximum around 90°W, resulting from the sum of different
surface heat fluxes having different signs and competing geographical patterns. Surface convergence and CWV gradually develop along the southeast Pacific warm band. The populationof shallow cumulus starts growing to form the south ITCZ in February, a month earlier thanvigorous deep convection that finally organizes in the south ITCZ in March. The double ITCZ
therefore does not emerge abruptly in
austral fall, but results from a series of distinctive evolutionary stages in the preceding
months, initiated by SST in the preceding
austral summer.
Simple experiments are next performed
to diagnose the key factors that give rise to
the southeast Pacific warm band. In theexperiments, the heat budget of the ocean
mixed layer is calculated with the surface
heat fluxes (longwave, shortwave, latentheat, advection, and upwelling), all derived
from satellite observations. The results suggest that the absorbed shortwave flux
primarily drives the southeast Pacific warm
band, enhanced to a lesser extent by ocean
upwelling (Figure 1). Insolation remains
near the annual maximum from australsummer through late February over thelatitudinal range of the south ITCZ, resulting
in a peak in tropical southeast Pacific SST
and the south ITCZ in March. It is now
obvious why the double ITCZ is absent inboreal fall: the incoming shortwave flux is
at a minimum in the preceding solstice season and thus incapable of maintaining awarm ocean surface in the southern hemi­ Fig. 1: SST computed from different experiments.
(Left) January-mean SST with a July-fixed flux. (Right)
sphere. The ocean mixed layer tends to cool
September-mean SST with a January-fixed flux. (Fromin July, when the shortwave flux is overtop to bottom) control, shortwave-fixed, advectionwhelmed by negative fluxes such as latent
fixed, upwelling-fixed, longwave↓-fixed, long­wave↑heat and longwave fluxes.
fixed, and latent heat-fixed runs.

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23
Variability of cirrus clouds over the Indian Ocean in boreal summer
A primary source of tropical cirrus clouds is often considered to be detrainment from deep
convective clouds. In general, the global distribution of cirrus clouds closely resembles thespatial pattern of deep convection in the tropics. This is, however, not always the case. Figure
2 shows that cirrus clouds in boreal summer are spread across the entire Indian Ocean, while
deep convective clouds are confined to the eastern part of the ocean and the Bay of Bengal.
Cirrus clouds over the equatorial Indian Ocean do not accompany deep convection, implyingthat a mechanism other than detrainment is at work for the formation and maintenance of
cirrus clouds in this particular example.

Fig. 2: Climatological boreal summer (June–August) of (top) cirrus cloud amount (CIA) and (bottom) deep convective
cloud amount (DCA): (a) From the ISCCP product for 1998–2005; (b) from the Cloud Sat product for 2006.

To explore this problem, temporal and spatial variations of cirrus clouds over the equatorial Indian Ocean are analyzed using the International Satellite Cloud Climatology Project(ISCCP) cloud datasets. Figure 3 shows the temporal variations of cirrus cloud amount (CIA)and deep convective cloud amount (DCA) over the equatorial Indian Ocean for 1998–2005.
CIA is not always in phase with DCA, having pronounced maxima that often do not accompany DCA peaks. Figure 3 also shows a 150-hPa temperature anomaly and 150–300-hPa
zonal wind shear. CIA varies in parallel with temperature anomaly and vertical wind shear
from time to time. It is suggested that fluctuations in upper-tropospheric temperature and/or
wind shear play some role in the in-situ formation of cirrus clouds without detrainment fromdeep convection.

Fig. 3: Time series of CIA (linewith crosses), DCA (histogram), 150-hPa temperature
anomaly (dashed line),and vertical wind shear
between 150 and 300 hPa(solid line) for 1998–2005.

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24 Division of Global – Scale Water Cycle Variations
Loboratory of Satellite Meteorology
Diurnal Variations in Low-Level Jet around Okinawa Island, Japan during Baiu Season
Horizontal winds with high temporal and vertical resolution from the 400-MHz windprofiler radar (WPR) at Okinawa, Japan and the Japan Meteorological Agency (JMA) WPRs
at three stations surrounding Okinawa were used to investigate the low-level jet (LLJ) during
the Baiu season months (May–June of 2004–2006), over the southwest islands of Japan. To
better understand the relationship of the LLJ to the Baiu rainfall system, the diurnal variations in precipitation associated with the Baiu front over this region were examined using
GSMaP (Global Satellite Mapping Precipitation) and Radar-AMeDAS (Automated Meteorological Data Acquisition System) rainfall data.
First, LLJ characteristics were investigated in two subperiods: the Baiu season over Okinawa Island and the post-Baiu season when the Baiu front has moved further north of Okinawa. LLJ occurrence varies diurnally with a maximum in the night-time and early morning,
especially in post-Baiu season. Upper-air soundings suggest that the preference for nocturnal
occurrence arises from the reduction of vertical mixing in the atmospheric boundary layer
after sunset. Data from the JMA WPR network for three other stations surrounding Okinawa
Island show more evidence for the role of the atmospheric boundary layer in generating diurnal variations in LLJ occurrence.
Therefore, diurnal variations in LLJ
occurrence were analyzed with focus
on the rain cases. Baiu precipitation
over the studied region varies diurnally, with peak intensity in the morning and propagation from northwest
to southeast. Thus, peak LLJ intensity in the morning at Okinawa is associated with propagation of a strong
precipitation band toward Okinawa
Island. However, the preferences fornight-time occurrence at Naze andYonaguni were likely related to thecloseness of precipitation when it approachedthose sites. Yakushima shows
Fig. 1. Diurnal variations in precipitation distribution around
Okinawa Island for May and June in 2004–2006, obless clear diurnal variations in bothtained from a satellite rain map.
LLJ occurrence and precipitation.

Fig. 2. Diurnal variations in low-level jet occurrence over Okinawa Island for May and June in 2004–2006:(a) Rain cases; (b) No-rain cases.

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25
Precipitation Characteristics over the Tibetan Plateau in Monsoon Season
The diurnal cycle of rainfall over the Tibetan Plateau is investigated by examining dataacquired by the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) overJune–August of 1998–2007. High spatial resolution data (0.05° × 0.05° grid: ~5 km × 5 km)
were used to identify topographic features over the complex region of the plateau. Diurnal
variations in rainfall amount, rainfall frequency, rain-conditioned rain rate, and storm height
were analyzed to determine the characteristics of precipitation. Distinct diurnal variations
were seen over hilly regions, valleys, and 13 large- and -medium sized lakes.

Fig. 3. Topography of the Tibetan Plateau.

Fig. 4. Diurnal variations in rainfall frequency (broken line) andrain-conditioned rain rate (solid line) in fraction in Junefor the years 1998–2007; the abscissa is the local time(LT) in hours and the ordinate is the rain fraction in percentage: (a) June; (b) July; (c) August; (d) September.

The Tibetan Plateau receives 300 mm of rainfall per year with more than 70% of rainfall
in June–August. Of these, July shows the strongest diurnal variation during summer. In July,
the peak time of convective rain is followed by the peak frequency of rainfall. Nocturnal andearly-morning rainfall shows a mixture of convective and persistent rainfall. In summer, precipitation activity over the Tibetan Plateau is generally strongest during late afternoon. Hilly
regions show dominant afternoon/late-afternoon peaks, while valleys show dominant lateevening and morning peaks. Similarly, lakes show late-evening and morning peaks. Valleys
with high surface undulation also show strong diurnal variation. Morning rainfall is distinctly evident over lakes. Peak rainfall time over lakes depends on lake size and topographic
slope around the lake. On average, the strength of the diurnal variation over a lake varies
inversely with the lake size. In this region air is rather dry and has weak prevailing winds.
Slope alone is insufficient, but a combination of lake water and surrounding slope may enhance morning rain.

Fig. 5. Diurnal variations in rainfall for 1998–2007; the abscissa is the local time (LT) in hours and theordinate is the rain fraction in percentage: (a) Over the northeastern hilly region of study [33.5°–
34.5°N, 91°–92°E]; (b) Yarlung Zanbo river valley; (c) Lake 15 in Fig. 3.

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26
Laboratory of Eco-Hydrometeorology
Day-to-day variation in diurnal maximum height of the atmospheric boundary layer over the
Loess Plateau in China
Temporal variations in the atmospheric boundary layer (ABL) over the Loess Plateau are
examined with a focus on day-to-day variations in the diurnal maximum ABL height. The
half-hourly ABL height was determined from vertical profiles of turbulence intensity observed
by a wind profiler radar. On days with extensive cloud cover by stratiform clouds, the ABL
was poorly defined, and estimating its height was not feasible. Accordingly, the ABL height
was estimated only for clear or partly clear days, which were selected with the use of net
longwave and downward shortwave radiation observed at the surface (Fig. 1). The maximum
ABL height varied significantly from day to day. In the afternoon on clear days, cumulus clouds
formed frequently and a deep cumulus-topped boundary layer developed. The diurnal maximum ABL height (Zi) reached as high as 3 km above the surface, which was much higher thanthat estimated using a slab model (Zical) with surface heat fluxes (Fig. 2). When the ABL grew
to high altitudes and was topped by cumulus clouds, the vertical gradient of potential temperature was relatively small above the ABL top (Fig. 2). This observation suggests that atmospheric stability above the capping inversion was sufficiently weak to allow cumulus cloudformation. Thus, the diurnal maximum ABL height over the Loess Plateau depends on not
only surface heat fluxes but also the atmospheric stability above the capping inversion.

Figure 1 Relationship between net longwave radiation (Ln: difference between downward and upward longwave radiation)and the ratio of the vertical component of direct solar
radiation (DSR_ver) to downward shortwave radiation(SW_down) from April to July 2005.
Each point indicates the daytime average value. The plots
are classified based on the cloud type.

Figure 2
Day-to-day variation of a) daytime meanlatent heat flux, b) daytime mean sensible
heat flux at 12/32 m height, and c) diurnal
maximum Zi (open bars), Zical (solid bars),
and the difference in the vertical gradientof potential temperature between 600 hPa
and 700 hPa at 08 BST (00 UTC).

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27
Numerical simulations of local circulation and cumulus generation over the Loess Plateau in China
Because the Loess Plateau consists of flat tablelands dissected by steep gullies, the topography has non-negligible effects on cumulus formation over the Plateau on the regional scale.
Accordingly, ABL development was simulated numerically for clear days in which the cumulustopped boundary layer grew to high altitudes. With the use of a cloud-resolving nonhydrostatic
model, simulations were performed under two sets of bottom boundary conditions: actual andflat terrain. Some of the findings from the simulations can be summarized as follows. Morecumulus clouds formed in the case with the actual terrain than in the case with flat terrain. Local circulation developed with horizontal and vertical scales of several kilometers over both theflat and real terrains. Over the flat terrain, the updrafts were distributed systematically and werecharacterized by Rayleigh–Bénard-type cellular convective structures; downdrafts emerged aroundthe updrafts. In contrast, over the actual terrain, updrafts developed exclusively above the surface
layer streaks that formed over the windward slopes and the edges of the tableland. Water vapor
was lifted nonhomogeneously by local circulation on the windward slopes and the edges of thetableland (Figs. 3 and 4). As a result, development of cumulus clouds at the top of the ABL wasevident only above these locations. Thus, the topography of the Loess Plateau significantly influences cumulus formation over the Plateau.

Figure 3 The distribution of vertically integrated cloud liquid water at 13 : 20 BST for the a) FLAT-DRY run, b) FLAT-WET
run, c) ACTUAL-DRY run, and d) ACTUAL-WET run. The contour lines for the ACTUAL runs indicate every 100m; the bold contour line indicates the flat tableland of 1200 m a.s.l.; the star indicates the location of the ABL
observation site.

ａ）

ｂ）

01-1.HyARC2008-E.indd 27

Figure 4a) Cross section of vertical and horizontal wind velocity from 28 to 33 km(x axis) and 26 km (y axis) at 13 : 20
BST for the ACTUAL-DRY run (seeFig. 3). The gray scale indicates vertical wind, and the vectors indicate
horizontal wind. The contour line
indicates the mixing ratio of water
vapor for every 2 g kg–1. The bold dotted line indicates the cloud edge,
defined as a mixing ratio of cloudliquid water of 1.0×10–4 g kg–1.
b) Cross section of the altitude.

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28
Laboratory of Ocean Climate Biology
The climate system surrounding us is governed by water and materials cycles in the hydrosphereand atmosphere on the Earth. In our laboratory, we aim in studying the inter-relation­ship between
climate change and ocean biogeochemistry on time scales ranging from a decade to a century. A
brief description of our laboratory’s activities is as follows.
l Ocean Primary Productivity Monitoring by Satellites

Primary productivity is one of the key processes in understanding the relationship between
climate change and ocean biogeochemistry. A global view of primary productivity can be attainedby satellite remote sensing; however, its quantitative estimation is hindered by lack of ground-truth
data on spatial and temporal scales. To fill this gap, we developed, as part of the Core Research for
Evolutional Science and Technology (CREST) program “Project on Ocean Productivity Profiling
System (POPPS)” during 1999–2004, an ocean productivity profiling system using an underwater
profiling buoy system and a custom-made fast repetition rate fluorometer (FRRF). We are now
developing a practical system for monitoring of ocean primary productivity by operating the productivity profiling system in combination with supporting data-handling systems to merge satellite
and in situ data. This is under a new 5-year continuation project “Ocean Primary Productivity
Moni­toring by Satellites” as a part of Solution Oriented Research for Science and Technology(SORST), which began in 2004. The goal of the project is to design a system for monitoring
global ocean primary productivity. The immediate task is to utilize satellite primary productivity
data validated by the profiling buoy system for process studies on ocean biogeochemistry in response to physical forcing in order to demonstrate the usefulness of the validated satellite data.

Long-term operation of ocean productivity profiling system in central Sagami Bay
The underwater profiling buoy system is composed of an underwater winch system and a
profiling buoy system. The profiling buoy is equipped with sensors, and normally deployed below
the euphotic zone (EZ). It ascends to thesurface on a preset schedule (once a day,at noon) and measures the vertical profile from the winch depth to the surface,
and then returns to the winch to await
the next cycle. A custom-made FRRF has
been installed as the main sensor, inwhich data processing is performed inreal time during the profiling measurements. All measured data are stored,with a part of the processed data beingtransmitted to the laboratory via a cellular phone when the buoy pops up to
the surface. This instrument was in operation for almost a year, from November 2007 to November 2008, at observation station S3 in central Sagami Bay.
Out of the 297 scheduled operations, 220
profiles were obtained successfully, with152 completed real-time data transmis- Fig. 1. Time-series data transmitted from the monitoring system
in central Sagami Bay during November 2007 to Novemsions. Data collected from the system areber 2008. (A) Temperature (°C), (B) salinity (psu), (C)shown in Fig. 1 (Julian day 0 = January
photosynthetically available radiation at noon (PAR; µE
1, 2008).
m–2 s–1), (D) Chl a-specific gross productivity (Pbc; mgC

During winter, chlorophyll a (Chl a)concentration was low (< 0.5  mg m–3)

01-1.HyARC2008-E.indd 28

mgChl–1 h–1), and (E) maximum fluorescence (FmD) corresponding to Chl a concentration.

09.7.31 5:15:08 PM

29
within a well-mixed water column, and increased later with the development of stratification in
the upper layer after April. Maximum Chl a conc. (> 2.0 mg m–3) was found at 15–25 m depth during summer, which was deeper than the subsurface PbC maximum. This implied that photosynthetically produced particles (phytoplankton) are removed immediately from the upper layer andaccumulate below. The peaks of PbC and Chl a did not appear exactly in parallel, which impliedthat subsequent processes such as grazing by zooplankton would partly control the phytoplankton
biomass and primary productivity. This is the first ever long-term, continuous in situ measurementof ocean productivity, which demonstrates that our monitoring system showed promise in its
ability to further understanding the natural variability of oceanic productivity.

Diurnal and seasonal variability in the physiological characteristics and productivity of marine
phytoplankton in Sagami Bay
Biological processes of phytoplankton in the ocean could significantly influence the dynamics of the ecosystem such as the storage and cycles of carbon. These biological processes,
including the productivity of phytoplankton, are subjected to environmental stress such as fluctuating temperature, salinity and irradiance. Under such varying conditions, photosynthetic strategies are most likely to occur to maintain productivity. The present study examined the diel andseasonal changes in physiological characteristics and productivity of phytoplankton using the
FRRF in Sagami Bay, Japan.
Lower photochemical quantum efficiency (Fv /Fm) was observed at the surface in spring andthe other seasons (Fig. 1). Fv /Fm measured at midday showed low values at the surface where PAR
was the highest, mainly because of nonphotochemical quenching, and it increased sharply at depth(Fig. 2). Fv /F0, an index indicating for photoinhibition (fraction of functional photosystem II reaction centers), also showed similar profiles and varied differently throughout the day. Fv /Fm andFv /F0 at the surface showed a clear diel pattern, with minimum values at around midday andmaximum values at dusk and dawn (Fig. 2). This pattern was observed for all seasons, implying acommon physiological strategy or mechanism. Comparing maximal Fv /Fm, relatively higher values
were observed in spring and summer, indicating that the cells were in a better physiological state.
Fv /F0 was also observed to vary with the seasons. The decrease in the functional PSII reaction
centers at the surface was as high as 80% in spring compared with around 40% in fall. In summer,with warmer and less saline water observed at the top layer of the water column, cells exihibited
only a 30% decrease in Fv /F0. In addition, reduction in the photosynthetic activity (PbC) was
minimal during summer even at the surface. This suggested that the cells living in a better physical environment in summer were much more tolerant to high irradiance than those cells in spring
and fall. Cells under high irradiance during the day and in the summer exhibited a photoacclimative strategy that permits continuous and uninterrupted photosynthesis by preventing photodamage. Such information on photosynthetic efficiency under varying environmental conditions isessential in quantifying primary productivity in the ocean.

Fig. 2. Diel variability in Fv /Fm and surface PAR in spring (A & D), summer (B & E), and fall (C & F).

01-1.HyARC2008-E.indd 29

09.7.31 5:15:09 PM

30
Laboratory of Bio-Physical Oceanography
Interannual variation in material transports through the eastern channel of the Tsushima Straits
Nutrient transports from the East China Sea into the Japan Sea through the Tsushima
Straits play an important role in the nutrient budget and biological productivity of the southern part of the Japan Sea. In order to evaluate seasonal and interannual variations in material transports through the Tsushima Straits, we have conducted hydrographic observation
across the eastern channel of the Tsushima Straits (ECTS) since 2005. We conducted observations twenty-three times along a single observation line.
Figure 1 shows volume, freshwater, and dissolved organic nitrogen (DIN) transports, respectively, averaged in August and September from 2005 to 2008. Each of these observed
variables reached its maximum in 2005 and its minimum in 2007. Interannual variations in
the volume, freshwater, and DIN transports indicate similar tendency: the variations in the
freshwater and DIN transports seem to be associated with variations in the volume transport.
However, although the volume transport in 2007 decreased by 29% from 2005, the freshwaterand DIN transports in 2007 decreased by 49% and 63%, respectively, compared with those in
2005. Therefore, the variations in the freshwater and DIN transports are not adequately explained by the change of the volume transport alone.
Mean sea surface salinities in the ECTS in 2005 and 2007 were 31.31 and 33.37 psu, respectively. This result suggests that Changjiang discharge decreased in 2007, as most of the
low-salinity water observed in the ECTS in summer originated in the Changjiang. In fact,
Changjiang discharge, averaged from May to July in 2007, decreased by 19% compared to2005. Considering the decrease rate of the volume transport and the river discharge, freshwater transport in 2007 is calculated to have been as 19.38×106 kg s–1. This value coincides
well with observed freshwater transport in 2007 of 17.25×106 kg s–1. The low freshwatertransport in 2007 is explained by the reduced volume transport and river discharge of the
Changjiang. Meanwhile, mean DIN concentrations in the ECTS in 2005 and 2007 were 4.93
and 2.90 μM, respectively. Water temperature has high correlation with nutrient concentration,and the water temperatures in the lower layer at the central part of the ECTS in 2005 and2008 were 16°C while those in 2006 and 2007 were 18°C. This difference of bottom watertemperature might be related to the interannual variation in DIN transport.

Fig. 1. Volume, freshwater, and DIN transports through the ECTS averaged in August and September from 2005
to 2008.

Enhancement of primary productivity in the southern East China Sea following episodic typhoon
passage and its interannual variation
Enhancement of primary productivity (PPenh) in the southern East China Sea (ECS) following typhoon passages was investigated using satellite data and a primary productivity (PP)model. A long-lasting southerly wind is important to push the Kuroshio shelfward, and the PPenh
following 16 typhoon passages was clearly observed to be associated with the variation in the
shelfward movement of Kuroshio that generates upwelling of nutrients. Accordingly, we found01-1.HyARC2008-E.indd 30

09.7.31 5:15:11 PM

31that the PPenh was determined by typhoon translation speed (TS, m s–1) and meridional wind (V,m s–1) measured at Yonaguni Island, showing that the slower TS and the higher southerly wind,
PPenh would be higher (Figs. 2a and 2b). The importance of long-lasting southerly winds and the
TS underlying PPenh could be formulated empirically as an equation that could explain 88% of
the variation in PPenh (Fig. 2c). Applying this equation, we calculated that typhoon passages accounted for a minimum range of 0.6–11.8% of the ECS summer — fall new productivity (NP),with the lowest value in 1993 (due to only one typhoon passage) and the highest in 2001
(associated with 6 typhoon passages). These results suggest that typhoon passage over thesouthern ECS is an important phenomenon supporting NP in the ECS.

Fig. 2. Relationships between PPenh and (a) TS (R2 = 0.76), and (b) V (R2 = 0.45). HT and NT are PPenh by Typhoon
Hai-Tang and Nock-Ten, respectively. Curves in (a) and (b) are non-linear regression lines. (c) Comparison between satellite-based and empirical equation-based PPenh (R2 = 0.88).

Short-term periodic decrease of water temperature in subsurface layer of Sagami Bay, Japan
Oceanographic conditions in Sagami Bay were investigated through an analysis of the POPPS
buoy data. In the subsurface layer (> 150 m), water temperature frequently decreased regardlessof the season (arrows in Fig. 3b), and strong eastward flows with speeds greater than 20 cm s–1 simultaneously formed in the surface layer (< 150 m) (Fig. 3). These fluctuations in subsurface watertemperature and surface flow had a period of 25–35 days, and particularly the flow fluctuation wasclosely related to variations of the Kuroshio axis south of Japan. These water temperature and flow
fluctuations occurred together with (1) an upwelling of cold, deeper water in the subsurface layerand (2) an enhancement (or formation) of a cyclonic circulation in the surface layer in the northern part of Sagami Bay. These correlations indicate the presence of short-term periodic fluctuations
in water temperature and flow fields of Sagami Bay, which are closely related to the Kuroshio
axis variations south of Japan, and it is considered that these fluctuations are caused by a responseof the density field to the flow field under geostrophic adjustment.

Fig. 3. (a) Vector stick plot of vertical mean low-passed filtered current between depths of 50 and 150vm and(b) depth-time plot of water temperature at depths of 0–200 m during a period from July 25, 2007 to
February 20, 2008. Shaded areas in (b) represent water temperature with values less than 14°C. Contour
intervals for water temperature are 1°C.

01-1.HyARC2008-E.indd 31

09.7.31 5:15:14 PM

32 List of Publications* : Staffs, students and research fellows in the HyARC.
01.

02.

03.

04.

05.

06.

07.

08.

09.

10.

11.
12.

13.

14.

15.

01-1.HyARC2008-E.indd 32

Chiba, S., M.N. Aita, K. Tadokoro, T. Saino*, H. Sugisaki and K. Nakata
From climate regime shifts to lower-trophic level phenology: Synthesis of recent pro­gress inretrospective studies of the western North Pacific. Progress In Oceano­graphy, 77, 112-126, 2008.
Eguchi, K., O. Abe and T. Hiyama*
Weight loss and isotopic shifts for water drops frozen on a liquid nitrogen surface. Rapid Communications in Mass Spectrometry, 22, 3233-3237, 2008.
Endo, S.*, T. Shinoda*, H. Tanaka*, T. Hiyama*, K. Tsuboki*, H. Uyeda* and K. Nakamura*
Characteristics of vertical circulation in the convective boundary layer over the Huaihe River
Basin in China in the early summer of 2004. Journal of Applied Meteorology and Climatology, doi:
10.1175/2008JAMC 1769.1, 2008. 47(11), 2911-2928, 2008.
Fujiki, T., T. Hosaka, H. Kimoto, T. Ishimaru and T. Saino*
In situ observation of phytoplankton productivity by an underwater profiling buoy system: useof fast repetition rate fluorometry. Marine Ecology Progress Series, l353, 81-88, 2008.
Hirose, M.*, R. Oki, S. Shimizu, M. Kachi and T. Higashiuwatoko
Fine-scale diurnal rainfall statistics refined from 8 years of TRMM PR data. Journal of Applied
Meteorology and Climatology, 47(2), 544-561, 2008.
Islam, M.N. and H. Uyeda*
Vertical variations of rain intensity in different rainy periods in and around Bangladesh derived
from TRMM observations. International Journal of Climatology, 28(2), 273-279, 2008.
Kawase, H., T. Yoshikane, M. Hara, B. Ailikun, F. Kimura and T. Yasunari*
Downscaling of the climatic change in the rainband in East Asia by a Psedo Climate Simulation
method. Scientific Online Letters on the Atmosphere (SOLA), 4, 73-76, doi: 10.2151/sola. 2008-019,
2008.
Liu, P., Y. Kajikawa, B. Wang, A. Kitoh, T. Yasunari*, T. Li, H. Annamalai, X. Fu, K. Kikuchi, R.
Mizuta, K. Rajendran, D.E. Waliser and D. Kim
Tropical Intraseasonal Variability in the MRI-20km60L AGCM. Journal of Climate, DOI: 10.1175/
2008JCLI2406.1, 2008.
Maeda, S., K. Tsuboki*, Q. Moteki, T. Shinoda*, H. Minda* and H. Uyeda*
Detailed Structure of Wind and Moisture Fields around the Baiu Frontal Zone over the East
China Sea. Scientific Online Letters on the Atmosphere (SOLA), 4, 141-144, doi: 10.2151/sola.
2008-036, 2008.
Masunaga, H.*, M. Satoh and H. Miura
A Joint Satellite and Global Cloud-Resolving Model Analysis of a Madden-Jullian Osci­l­la­­tion
Event: Model Diagnosis. Journal of Geophysical Research, 113, D17210, doi: 10.1029/2008JD009986,
2008.
Minda, H.*, F. A. Furuzawa*, S. Satoh and K. Nakamura*
Bird migration echoes observed by polarimetric radar. IEICE, E91-B, 6, 2085-2089, 2008.
Miyazaki, C. and T. Yasunari*
Dominant interannual and decadal variability of winter surface air temperature over Asia andthe surrounding oceans. Journal of Climate, 21(6), 1371-1386, 2008.
Moteki,  Q.,  R.  Shirooka,  H.  Kubota,  T.  Ushiyama,  K.K.  Reddy,  K.  Yoneyama,  M. Katsumata,N. Sato, K. Yasunaga, H. Yamada, B. Geng, M. Fujita, M. Yoshizaki, H. Uyeda* and T. Chuda
Mechanism of the northward propagation of mesoscale convective systems observed on 15 June
2005 during PALAU2005. Journal of Geophysical Research, 113, D14126, doi: 10.1029/2008JD009793,
2008.
Nishikawa, M.*, T. Hiyama*, K. Tsuboki* and Y. Fukushima
Numerical simulations of local circulation and cumulus generation over the Loess Plateau, China.
Journal of Applied Meteorology and Climatology, doi: 10.1175/JAMC­2041.1, 2008.
Ohta, T., T.C. Maximov, A.J. Dolman, T. Nakai, M.K. van der Molen, A.V. Kononov, A.P. Maximov,
T. Hiyama*, Y. Iijima, E.J. Moors, H. Tanaka*, T. Toba and H. Yabuki
Interannual variation of water balance and summer evapotranspiration in an eastern Siberian
larch forest over a 7-year period (1998-2006). Agricultural and Forest Meteor­o­logy, 148, 1941-1953,
2008.

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33
16.

17.

18.

19.

20.

21.

22.

23.

24.

25.

26.

27.

28.

01-1.HyARC2008-E.indd 33

Pham, N.T.*, K. Nakamura*, F.A. Furuzawa* and S. SatohCharacteristics of Low Level Jets over Okinawa in the Baiu and post-Baiu Seasons reveal­ed byWind Profiler Observations. Journal of the Meteorological Society of Japan, 86(5), 699-717, 2008.
Prasanna, V.* and T. Yasunari*Interannual variability of atmopsheric water balance over south Peninsular India and Sri Lanka
during northeast monsoon season. International Journal of Climatology, 28(15), 1997-2009, doi:
10.1002/joc.1683, 2008.
Rao, T.N., N.V.P. Kirankumar, B. Radhakrishna, D.N. Rao and K. Nakamura*Classification of Tropical Precipitating Systems Using Wind Profiler Spectral Moments: 1. Algorithm Description and Validation. Journal of Atmospheric and Oceanic Tech­nology, 25(6), 898-908,
2008.
Rao, T.N., N.V.P. Kirankumar, B. Radhakrishna, D.N. Rao and K. Nakamura*Classification of Tropical Precipitating Systems Using Wind Profiler Spectral Moments: 2. Statistical characteristics of rainfall systems and sensitivity analysis. Journal of Atmos­pher­ic andOceanic Technology, 25(6), 884-897, 2008.
Renfrew, I.A., G.W.K. Moore, J.E. Kristjansson, H. Olafsson, S.L. Gray, G.N. Petersen, K. Bovis,
P.R.A. Brown, I. Fore, T. Haine, C. Hay, E.A. Irvine, A. Lawrence, T. Ohigashi*, S. Outten, R.S.
Pickart, M. Shapiro, D. Sproson, R. Swinbank, A. Woolley and S. Zhang
The Greenland Flow Distortion experiment. Bulletin of the American Meteorological Society, 89(9),1307-1324, 2008.
Sato, T., T. Yoshikane, M. Satoh, H. Miura and H. Fujinami*
Resolution dependency of the diurnal cycle of convective clouds over the Tibetan Plateau in a mesoscale model. Journal of Meteorological Society of Japan, 86A, 17-31, 2008.
Shimizu, S., H. Uyeda*, Q. Moteki, T. Maesaka, M. Takaya, K. Akaeda, T. Kato and M. Yoshizaki
Structure and formation mechanism of 24 May 2000 supercell-like thunderstorm observed over
Kanto plain, Japan. Monthly Weather Review, 136(7): 2389-2407, 2008.
Siswanto, E.*, H. Nakata, Y. Matsuoka, K. Tanaka, Y. Kiyomoto, K. Okamura, J. Zhu and J.
Ishizaka
The long-term freshening and nutrient increases in summer surface water in the northern East
China Sea in relation to Changjiang discharge variation. Journal of Geophysical Research, 113,2008.
Siswanto, E.*, J. Ishizaka, A. Morimoto*, K. Tanaka, K. Okamura, A. Kristijono and T. Saino*
Ocean physical and biogeochemical responses to the passage of Typhoon Meari in the East
China Sea observed from Argo float and multiplatform satellites. Geophysical Research Letters,
35, 2008.
Takahashi, A., T. Hiyama*, M. Nishikawa*, H. Fujinami*, A. Higuchi, W. Li, W. Liu and Y.
Fukushima
Diurnal variation of water vapor mixing between the atmospheric boundary layer and free atmosphere over Changwu, the Loess Plateau in China. Scientific Online Letters on the Atmosphere(SOLA), 4, 33-36, 2008.
Takahashi, C., H. Uyeda*, M. Maki, K. Iwanami and R. Misumi
Relationships among Structures, Development Processes, and Heating Profiles for Two Mesoscale
Convective Systems in Inactive Phase of a Large-Scale Disturbance over Northern Australia during the Southern Summer in 1998-1999. Journal of the Mete­or­olog­ical Society of Japan, 86(1),81-117, 2008.
Takahashi, H.G., T. Yoshikane, M. Hara and T. Yasunari*High-resolution regional climate simulations of the long-term decrease in September rainfall
over Indochina. Atmospheric Science Letters, 10(1), 14-18, doi: 10.1002/asl. 203, 2008.
Takikawa, T., A. Morimoto*, G. Onitsuka, A. Watanabe* and M. Moku
Characteristics of Water Mass under the Surface Mixed Layer in Tsushima Straits and the Southwestern Japan Sea in Autumn. Journal of Oceanography, 64(4), 585-594, 2008.

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34
29.

30.

31.

32.

33.

34.

01-1.HyARC2008-E.indd 34

Tanaka, H.*, T. Hiyama* and K. Nakamura*
Turbulent flux observations at the tip of a narrow cape on Miyako Island in Japan’s Southwestern
Islands. Journal of the Meteorological Society of Japan, 86(5), 649-667, 2008.
Tanaka, H.*, T. Hiyama*, N. Kobayashi, H. Yabuki, Y. Ishii, R.V. Desyatkin, T.C. Maximov and T.
Ohta
Energy balance and its closure over a young larch forest in eastern Siberia. Agricultural and Forest Meteorology, 148, 1954-1967, 2008.
Tangang, F.T., L. Juneng, E. Salimun, P.N. Vinayachandran, Y.K. Seng, C.J.C. Reason, S.K.
Behera and T. Yasunari*
On the roles of the northeast cold surge, the Borneo vortex, the Madden-Julian Oscil­la­tion, andthe Indian Ocean Dipole duringthe extreme 2006/2007 flood in southern Peninsular Malaysia.
Geophysical Research Letters, 35, L14S07, doi: 10.1029/2008GL­0­33429, 2008.
Tsuboki, K.*
High-Resolution Simulations of High-Impact Weather Systems Using the Cloud-Resolving Modelon the Earth Simulator. High Resolution Numerical Modelling of the Atmosphere and Ocean,
Hamilton, Kevin; Ohfuchi, Wataru (Eds.), Springer New York, 141-156. 2008.
Uyeda*, H.
Mesoscale Precipitation Systems Along the Meiyu/Baiu Front and Future Expectation for Research
Radar and Weather Radar Network. Journal of Disaster Research, 3(1), 61-68, 2008.
Yamamoto, K.M., F.A. Furuzawa*, A. Higuchi and K. Nakamura*Comparison of diurnal variations in precipitation systems observed by TRMM PR, TMI, and
VIRS. Journal of Climate, 21(16), 4011-4028, 2008.

09.7.31 5:15:14 PM

Hydrospheric Atmospheric Research Center (HyARC)
Nagoya University
Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
Office:Telephone: +81-52-789-3466
Facsimile: +81-52-789-3436
Home Page: http://www.hyarc.nagoya-u.ac.jp/hyarc/

The 2008 Annual Report was published July 2009 by the
Hydrospheric Atmospheric Research Center (HyARC) Nagoya
University. Copies of this report are available from the officeof the Center.

Printed by Nagoya University COOP

Annual Report

Hydrospheric Atmospheric Research Center(HyARC)
Nagoya University

2010