研究者詳細 - 増永　浩彦

論文 - 増永　浩彦

分割表示 68 件中 41 - 60 件目／全件表示 >>

Analysis of cloud properties associated with tropical convection in climate models and satellite data 査読有り

気象集誌 90 巻頁： 629-646 2012年

Short-term versus climatological relationship between precipitation and tropospheric humidity 査読有り

25 巻頁： 7983-7990 2012年

Reproducibility by climate models of cloud radiative forcing associated with tropical convection 査読有り

25 巻頁： 1247-1262 2012年

A satellite study of the atmospheric forcing and response to moist convection over tropical and subtropical oceans 査読有り

69 巻頁： 150-167 2012年

Equatorial asymmetry of the east Pacific ITCZ: Observational constraints on the underlying processes 査読有り

Masunaga, H. and T. S. L'Ecuyer

J. Climate 24 巻頁： 1784-1800 2011年3月

Satellite Data Simulator Unit (SDSU): A multi-sensor, multi-spectral satellite simulator package 査読有り

Masunaga, H., T. Matsui, W.-K. Tao, A. Y. Hou, C. D. Kummerow, T. Nakajima, P. Bauer, W. S. Olson, M. Sekiguchi, and T. Y. Nakajima

Bull. Amer. Meteorol. Soc. 91 巻頁： 1625-1632 2010年12月

The southeast Pacific warm band and double ITCZ 査読有り

Masunaga, H. and T. S. L'Ecuyer

J. Climate 23 巻頁： 1189-1208 2010年

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

The east Pacific double intertropical convergence zone (ITCZ) in austral fall is investigated with particular
focus on the growing processes of its Southern Hemisphere branch. Satellite measurements from the Tropical
Rainfall Measuring Mission (TRMM) and Quick Scatterometer (QuikSCAT) are analyzed to derive 8-yr
climatology from 2000 to 2007. The earliest sign of the south ITCZ emerges in sea surface temperature (SST)
by January, followed by the gradual development of surface convergence and water vapor. The shallow
cumulus population starts growing to form the south ITCZ in February, a month earlier than vigorous deep
convection is organized into the south ITCZ. The key factors that give rise to the initial SST enhancement or
the southeast Pacific warm band are diagnosed by simple experiments. The experiments are designed to
calculate SST, making use of an ocean mixed layer ‘‘model’’ forced by surface heat fluxes, all of which are
derived from satellite observations. It is found that the shortwave flux absorbed into the ocean mixed layer is
the primary driver of the southeast Pacific warm band. The warm band does not develop in boreal fall because
the shortwave flux is seasonally so small that it is overwhelmed by other negative fluxes, including the latent
heat and longwave fluxes. Clouds offset the net radiative flux by 10–15 W m22, which is large enough for the
warm band to develop in boreal fall if it were not for clouds reflecting shortwave radiation. Interannual
variability of the double ITCZ is also discussed in brief.

Improving a spectral bin microphysical scheme using TRMM satellite observations 査読有り

Li, X., W.-K. Tao, T. Matsui, C. Liu, and H. Masunaga

Quart. J. Roy. Meteor. Soc. 136 巻頁： 382-399 2010年

記述言語：英語掲載種別：研究論文（学術雑誌）

TRMM-observed mature-stage squall lines during late spring and early summer
in the central USA over a 9-year period are compiled and compared with a case
simulation by the Goddard Cumulus Ensemble (GCE) model with a spectral bin
microphysical scheme. During the quasi-steady state of the simulation, a forward
radiative transfer model calculates TRMM Precipitation Radar (PR) reflectivity
and 85 GHz brightness temperatures from simulated particle size distributions.
Comparisons between model and TRMM observations using radar Contoured
Frequency with Altitude Diagrams (CFADs) and 85 GHz brightness temperature
probability density distributions are performed, in addition to CFADs from a surface
C-band radar for the same case. Radar CFADs comparisons reveal that the model
overestimates sizes of snow/aggregates in the stratiform region.
Three sets of sensitivity tests are carried out in order to improve the simulated
radar reflectivity profiles: increase of aggregates’ density and terminal fall velocity;
changing temperature dependency of collection efficiency between ice-phase
particles, particularly those of the plate-type; and adding a break-up scheme for
large aggregates. While all three approaches mitigate the discrepancies, changing
collection efficiency produces the best match in magnitudes and characteristics
of radar CFADs. In addition, interactions between ice- and water-phase particles
also need to be adjusted in order to have good comparisons in both radar CFADs
and 85 GHz brightness temperature distributions. This study shows that long-term
satellite observations, especially those with multiple sensors, can be very useful in
constraining model microphysics.

A 9-season TRMM observation of the Austral Summer MJO and Low-frequency Equatorial Waves 査読有り

Masunaga, H.

気象集誌 87A 巻頁： 295-315 2009年

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

A long-term observation from the Tropical Rainfall Measuring Mission (TRMM) is analyzed to investigate the Madden-Julian Oscillation (MJO), Kelvin wave, and equatorial Rossby (ER) wave in austral summer seasons. TRMM Precipitation Radar (PR) and Visible/Infrared Scanner (VIRS) measurements are jointly used to clarify convective progression associated with individual modes of the tropical oscillations. Variability in the dynamic and thermodynamic environment involving sea surface temperature (SST), column relative humidity (CRH), and moisture convergence is also examined. A sea surface warming is found to precede the peak MJO convection by ∼ 10 days, while a prior SST increase is not as evident for the Kelvin and ER waves. Moisture convergence and CRH exhibit a horseshoe-like pattern in the composite MJO map, constituted of a pair of off-equatorial maxima and a weak equatorial peak. The Kelvin wave has a moist anomaly on the equator leading the convective peak as theoretically expected, while the moist anomaly also extends poleward without being accompanied by moisture convergence. Moisture convergence leads CRH by a day or two for the Kelvin and ER waves. Moisture convergence is, in contrast, virtually concurrent with CRH for the MJO. The correlation between CRH and deep stratiform coverage is diverse among the three modes of the tropical oscillations. Shallow cumulus and cumulus congestus lead the MJO convective peak by ∼ 1 day, followed by lingering non-precipitating high clouds. ER wave convection is led by moisture convergence but lagged by CRH. The convective progression appears not to proceed in a monotonic way for the ER wave.
A possible mechanism to explain MJO propagation is discussed as suggested by a synthesis of the present findings. The Kelvin wave guides the eastward migration of MJO convection onset over the Indian Ocean. The role of the Kelvin wave in MJO propagation diminishes as the MJO enters the west Pacific with the convective are

An MJO simulated by the NICAM at 14-km and 7-km resolutions 査読有り

Liu, P., M. Satoh, B. Wang, H. Fudeyasu, T. Nasuno, T. Li, H. Miura, H. Taniguchi, H. Masunaga, X. Fu, and H. Annamalai

Mon. Wea. Rev. 137 巻頁： 3254-3268 2009年

記述言語：英語掲載種別：研究論文（学術雑誌）

This study discloses detailed Madden–Julian oscillation (MJO) characteristics in the two 30-day integrations
of the global cloud-system-resolving Nonhydrostatic Icosahedral Atmospheric Model (NICAM) using the allseason
real-time multivariateMJO index ofWheeler and Hendon. The model anomaly is derived by excluding
the observed climatology because the simulation is sufficiently realistic.Results showthat theMJOhas a realistic
evolution in amplitude pattern, geographical locations, eastward propagation, and baroclinic- and westwardtilted
structures. In the central IndianOcean, convection develops with the low-level easterlywind anomaly then
matures where the low-level easterly and westerly anomalies meet. Anomalous moisture tilts slightly with
height. In contrast, over the western Pacific, the convection grows with a low-level westerly anomaly.Moisture
fluctuations, leading convection in eastward propagation, tilt clearly westward with height. The frictional
moisture convergence mechanism operates to maintain the MJO. Such success can be attributed to the explicit
representation of the interactions between convection and large-scale circulations. The simulated event, however,
grows faster in phases 2 and 3, and peaks with 30%higher amplitude than that observed, although the 7-km
version shows slight improvement. The fast-growth phases are induced by the fast-growing low-level convergence
in the IndianOcean and the strongly biased ITCZ in the west Pacific when themodel undergoes a spinup.
The simulated OLR has a substantial bias in the tropics. Possible solutions to the deficiencies are discussed.
1. Introduction
The Madden–Julian oscillation (MJO; Madden and
Julian 1971, 1972, 1994) dominates tropospheric variability
in the tropics on time scales of 30–60 days. The
oscillation influences weather and climate variability
substantially in both the tropics (e.g., Yasunari 1979;
Hendon and Liebmann 1990; Lawrence and Webster
2002) and

Evaluation of Precipitation and High-level Cloud Areas Associated with Large-scale Circulation over the Tropical Pacific in the CMIP3 Models 査読有り

Ichikawa, H., H. Masunaga, and H. Kanzawa

気象集誌 87 巻頁： 771-789 2009年

記述言語：英語掲載種別：研究論文（学術雑誌）

Precipitation and high-level cloud (HLC) areas in association with the large-scale circulation over the tropical
Pacific are analyzed for simulations of nineteen Coupled Model Intercomparison Project Phase 3 (CMIP3) models
with observations for 16 years of 1984–1999. The distribution of rainfall and HLC areas are composited around
the geographical center of tropospheric upper-level (200 hPa) divergence (DIV) along Intertropical Convergence
Zone (ITCZ) using monthly anomaly data. Datasets with a finer temporal sampling than monthly means were
not available for the present purposes. The most notable feature is that the horizontal spread of enhanced circulation
and the related rainfall and HLC areas are all underestimated around the DIV center in the models compared
to the observation. Particularly, the underestimation is pronounced in HLC, presumably owing to di‰culties
in the physical processes relevant to the spatial distribution of HLC area. In general, a model with a higher
correlation between the large-scale circulation field and rainfall tends to have a wider spread of HLC area around
the DIV center.

A Joint Satellite and Global Cloud-Resolving Model Analysis of a Madden-Jullian Oscillation Event: Model Diagnosis 査読有り

Masunaga, H., M. Satoh, and H. Miura

J. Geophys. Res. 113 巻 ( D17210 ) 頁： doi:10.1029/2008JD009986 2008年9月

*Seasonality and Regionality of the Madden-Julian Oscillation, Kelvin Wave, and Equatorial Rossby Wave. 査読有り

Masunaga, H.

J. Atmos. Sci. 64 巻頁： 4400-4416 2007年12月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

The Madden–Julian oscillation (MJO), Kelvin wave, and equatorial Rossby (ER) wave—collectively
called intraseasonal oscillations (ISOs)—are investigated using a 25-yr record of outgoing longwave radiation
(OLR) measurements as well as the associated dynamical fields. The ISO modes are detected by
applying bandpass filters to the OLR data in the frequency–wavenumber space. An automated wavetracking
algorithm is applied to each ISO mode so that convection centers accompanied with the ISOs are
traced in space and time in an objective fashion. The identified paths of the individual ISO modes are first
examined and found strongly modulated regionally and seasonally. The dynamical structure is composited
with respect to the convection centers of each ISO mode. A baroclinic mode of the combined Rossby and
Kelvin structure is prominent for the MJO, consistent with existing work. The Kelvin wave exhibits a
low-level wind field resembling the shallow-water solution, while a slight lead of low-level convergence over
convection suggests the impact of frictional boundary layer convergence on Kelvin wave dynamics. A lagged
composite analysis reveals that the MJO is accompanied with a Kelvin wave approaching from the west
preceding the MJO convective maximum in austral summer. MJO activity then peaks as the Kelvin and ER
waves constructively interfere to enhance off-equatorial boundary layer convergence. The MJO leaves a
Kelvin wave emanating to the east once the peak phase is passed. The approaching Kelvin wave prior to the
development of MJO convection is absent in boreal summer and fall. The composite ER wave, loosely
concentrated around the MJO, is nearly stationary throughout. A possible scenario to physically translate
the observed result is also discussed.

*The Madden-Julian Oscillation Recorded in Early Observations from the Tropical Rainfall Measuring Mission (TRMM). 査読有り

Masunaga, H., T. S. L'Ecuyer, and C. D. Kummerow

J. Atmos. Sci. 63 巻頁： 2777-2794 2006年11月

Observations of Tropical Precipitating Clouds Ranging from Shallow to Deep Convective Systems. 査読有り

Masunaga, H., and C. D. Kummerow

Geophys. Res. Lett. 33 巻 ( L16805 ) 頁： doi:10.1029/2006GL026547 2006年8月

Variability in the Characteristics of Precipitation Systems in the Tropical Pacific.Part II: Implications for Atmospheric Heating 査読有り

TRISTAN S. L’ECUYER, HIROHIKO MASUNAGA, AND CHRISTIAN D. KUMMEROW

J. Climate 19 巻頁： 1388-1406 2006年

Satellite-based Assessment of Marine Low Cloud Variability Associated with Aerosol, Atmospheric Stability, and the Diurnal Cycles. 査読有り

Matsui, T., H. Masunaga, R. A. Pielke Sr., S. M. Kreidenweis, W.-K. Tao, M. Chin, and Y. J. Kaufman

J. Geophys. Res. 111 巻 ( D17204 ) 頁： doi:10.1029/2005JD006097 2006年

*Combined Radar and Radiometer Analysis of Precipitation Profiles for a Parametric Retrieval Algorithm. 査読有り

Masunaga, H. and C. D. Kummerow

J. Atmos. Oceanic Tech. 22 巻頁： 909-929 2005年

*Variability in the Characteristics of Precipitation Systems in the Tropical Pacific. Part I. Spatial Structure. 査読有り

Masunaga, H., T. S. L'Ecuyer, and C. D. Kummerow

J. Climate 18 巻頁： 823-840 2005年

Impact of aerosols and atmospheric thermodynamics on cloudproperties within the climate system 査読有り

Toshihisa Matsui, Hirohiko Masunaga, and Roger A. Pielke Sr.

Geophys. Res. Lett. 31 巻 ( L06109 ) 頁： doi:10.1029/2003GL019287 2004年

　前のページ - 次のページ　

<増永 浩彦>

論文 - 増永 浩彦

<増永　浩彦>

論文 - 増永　浩彦