Miho Sekiguchi

Improved Climate Simulation by MIROC5: Mean States, Variability, and Climate Sensitivity

Abstract A new version of the atmosphere–ocean general circulation model cooperatively produced by the Japanese research community, known as the Model for Interdisciplinary Research on Climate (MIROC), has recently been developed. A century-long control experiment was performed using the new version (MIROC5) with the standard resolution of the T85 atmosphere and 1° ocean models. The climatological mean state and variability are then compared with observations and those in a previous version (MIROC3.2) with two different resolutions (medres, hires), coarser and finer than the resolution of MIROC5. A few aspects of the mean fields in MIROC5 are similar to or slightly worse than MIROC3.2, but otherwise the climatological features are considerably better. In particular, improvements are found in precipitation, zonal mean atmospheric fields, equatorial ocean subsurface fields, and the simulation of El Nino–Southern Oscillation. The difference between MIROC5 and the previous model is larger than that between th...

Significance of direct and indirect radiative forcings of aerosols in the East China Sea region

� 8W /m 2 at the top of atmosphere (TOA) and � 10 to � 23 W/m 2 at Earth’s surface of Gosan (33.28N, 127.17E) and Amami-Oshima (28.15N, 129.30E) sites, though there is a large regional difference caused by changes in the aerosol optical thickness and single scattering albedo. The cloud forcing is estimated as � 20 to � 40 W/m 2 , so that the aerosol direct forcing can be comparable to the cloud radiative forcing at surface. However, the estimate of the aerosol direct forcing thus obtained strongly depends on the estimation method of the aerosol properties, especially on the single scattering albedo, generating a method difference about 40%. The radiative forcing of the aerosol indirect effect is roughly estimated from satellite method and SPRINTARS model as � 1t o� 3W /m 2 at both TOA and surface. INDEX TERMS: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801); 0345 Atmospheric Composition and Structure: Pollution—urban and regional (0305); 1610 Global Change: Atmosphere (0315, 0325); 9320 Information Related to Geographic Region: Asia;

Characterization of Asian dust and Siberian smoke with multi- wavelength Raman lidar over Tokyo, Japan in spring 2003

[1] In the spring of 2003, we observed lofted Asian dust and Siberian forest-fire smoke plumes in the free troposphere over Tokyo, Japan with a dual-wavelength Raman lidar. These data show clear signatures of the optical characteristics depending on the aerosol type. The Asiandust layer shows that the particle depolarization ratio (PDR) at 532 nm is 20%, and the extinction-to-backscatter ratio (lidar ratio) at 355 nm is 49 sr, which is close to 43 sr measured at 532 nm. On the contrary, the smoke layers show that the PDR is as small as 5–8% or less, and the lidar ratio at 355 nm is 40 sr, which is considerably lower than 65 sr which was measured at 532 nm. We also applied an inversion algorithm for the smoke case. The effective radius was 0.22 mm and the single-scattering albedo at 532 nm was 0.95. INDEX TERMS: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801); 0368 Atmospheric Composition and Structure: Troposphere— constituent transport and chemistry; 0394 Atmospheric Composition and Structure: Instruments and techniques.

Satellite Data Simulator Unit: A Multisensor, Multispectral Satellite Simulator Package

AmerIcAN meTeOrOLOGIcAL SOcIeTY | 1625 AffiliAtions: Masunaga—Hydrospheric Atmospheric Research Center, Nagoya University, Nagoya, Japan; Matsui, tao, Hou, and olson—NASA Goddard Space Flight Center, Greenbelt, Maryland; KuMMerow—Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado; te. naKajiMa—Atmosphere and Ocean Research Institute, University of Tokyo, Chiba, Japan; Bauer—European Centre for Medium-Range Weather Forecasts, Reading, United Kingdom; seKigucHi—Faculty of Marine Technology, Tokyo University of Marine Science and Technology, Tokyo, Japan; ta. Y. naKajiMa— Research and Information Center, Tokai University, Tokyo, Japan Corresponding Author: Hirohiko Masunaga, Hydrospheric Atmospheric Research Center, Nagoya University, F3-1(200) Furocho Chikusa-ku, Nagoya 464-8601, Japan E-mail: masunaga@hyarc.nagoya-u.ac.jp

Radiative flux and forcing parameterization error in aerosol‐free clear skies

Abstract This article reports on the accuracy in aerosol‐ and cloud‐free conditions of the radiation parameterizations used in climate models. Accuracy is assessed relative to observationally validated reference models for fluxes under present‐day conditions and forcing (flux changes) from quadrupled concentrations of carbon dioxide. Agreement among reference models is typically within 1 W/m2, while parameterized calculations are roughly half as accurate in the longwave and even less accurate, and more variable, in the shortwave. Absorption of shortwave radiation is underestimated by most parameterizations in the present day and has relatively large errors in forcing. Error in present‐day conditions is essentially unrelated to error in forcing calculations. Recent revisions to parameterizations have reduced error in most cases. A dependence on atmospheric conditions, including integrated water vapor, means that global estimates of parameterization error relevant for the radiative forcing of climate change will require much more ambitious calculations.

Introducing multisensor satellite radiance‐based evaluation for regional Earth System modeling

Earth System modeling has become more complex, and its evaluation using satellite data has also become more difficult due to model and data diversity. Therefore, the fundamental methodology of using satellite direct measurements with instrumental simulators should be addressed especially for modeling community members lacking a solid background of radiative transfer and scattering theory. This manuscript introduces principles of multisatellite, multisensor radiance-based evaluation methods for a fully coupled regional Earth System model: NASA-Unified Weather Research and Forecasting (NU-WRF) model. We use a NU-WRF case study simulation over West Africa as an example of evaluating aerosol-cloud-precipitation-land processes with various satellite observations. NU-WRF-simulated geophysical parameters are converted to the satellite-observable raw radiance and backscatter under nearly consistent physics assumptions via the multisensor satellite simulator, the Goddard Satellite Data Simulator Unit. We present varied examples of simple yet robust methods that characterize forecast errors and model physics biases through the spatial and statistical interpretation of various satellite raw signals: infrared brightness temperature (Tb) for surface skin temperature and cloud top temperature, microwave Tb for precipitation ice and surface flooding, and radar and lidar backscatter for aerosol-cloud profiling simultaneously. Because raw satellite signals integrate many sources of geophysical information, we demonstrate user-defined thresholds and a simple statistical process to facilitate evaluations, including the infrared-microwave-based cloud types and lidar/radar-based profile classifications.

Importance of instantaneous radiative forcing for rapid tropospheric adjustment

To better understand CFMIP/CMIP inter-model differences in rapid low cloud responses to CO2 increases and their associated effective radiative forcings, we examined the tropospheric adjustment of the lower tropospheric stability (LTS) in three general circulation models (GCMs): HadGEM2-A, MIROC3.2 medres, and MIROC5. MIROC3.2 medres showed a reduction in LTS over the sub-tropical ocean, in contrast to the other two models. This reduction was consistent with a temperature decrease in the mid-troposphere. The temperature decrease was mainly driven by instantaneous radiative forcing (RF) caused by an increase in CO2. Reductions in radiative and latent heating, due to clouds, and in adiabatic and advective heating, also contribute to the temperature decrease. The instantaneous RF in the mid-troposphere in MIROC3.2 medres is inconsistent with the results of line-by-line (LBL) calculations, and thus it is considered questionable. These results illustrate the importance of evaluating the vertical profile of instantaneous RF with LBL calculations; improved future model performance in this regard should help to increase our confidence in the tropospheric adjustment in GCMs.

Transdisciplinary co-design of scientific research agendas: 40 research questions for socially relevant climate engineering research

Interest in climate engineering research has grown rapidly owing to the slow progress of international climate negotiations. As some scientists are proposing to expand research and conduct field tests, there is an emerging debate about whether and how it should proceed. It is widely accepted both by the supporters and critics that public engagement from the early stage of research is necessary. Nonetheless, most, if not all, of existing research projects of climate engineering were designed predominantly by experts. To produce socially relevant knowledge, and hence, pursue transdisciplinary research that integrates interdisciplinary research and public engagement, it is desirable for scientists to decide together with the public on what kind of research should be done. In this paper, we both as Japanese scientists and stakeholders collaboratively identify 40 socially relevant research questions on climate engineering with a particular emphasis on stratospheric aerosol injection, using a method designed to encourage science–policy collaboration. While we acknowledge some methodological problems and the difficulty in obtaining active participation from stakeholders, the list of identified questions covers broad interdisciplinary perspectives and diverse interests, and may provide an important foundation for future transdisciplinary research on climate engineering. Given the dynamic nature of climate change and policy responses, research agendas should be periodically and iteratively reviewed and updated through transdisciplinary processes.

The Improvement of The Absorption Process Using A Computational Optimization in An Atmospheric General Circulation Model

This study improves the gaseous absorption process scheme of the broadband radiative transfer code “mstrnX” that was developed by the Center for Climate System Research (CCSR) for efficient calculation of atmospheric radiative transfer in the general circulation models. This scheme is adopted the optimization method to decrease the number of quadrature points for wavenumber integration by using the correlated k‐distribution method and to increase the computational efficiency in each spectral band. The objective function of the standard version is defined as the sum of errors in radiation fluxes and heating rate in six standard atmospheres, and we added six other atmospheric profiles in the doubling CO2 condition for the doubling CO2 version. The preferable errors of radiative flux is thought about 1–2 W/m2, however, it is desirable that the errors of radiative forcing of CO2 is less than 0.3 W/m2. So, we improve the doubling CO2 version to calculate the radiative forcings precisely. When integration point...

Cirrus cloud radiative forcing at the top of atmosphere using the nighttime global distribution with the microphysical parameters derived from AVHRR

The radiative effect of cirrus clouds is particularly ambiguous in the climate research. We calculated the global cirrus cloud radiative forcing (CRFci) distributions at the top of the atmosphere (TOA) using the cloud microphysical parameters of effective radius (Re), optical thickness (COT) and the cloud top temperature (CTT) derived from AVHRR nighttime data. The results indicate that cirrus clouds warm the atmosphere, and in particular produce a large warming effect in the tropics. We also computed the dependence of radiative forcing on the effective radius of cloud particles, the optical thickness of the cloud, and the cloud-top temperature (CTT) and determined that cooling effects occur with clouds when their optical thickness is greater than 4.0∼4.5 with a cloud top temperature of 220K and 2.5∼3.0 with a cloud top temperature of 235K. Cloud radiative forcing in April 1987 (El Nino year) and April 1990 (neutral year) were computed, and found that a larger amount of cirrus clouds appeared in the tropics off Peru in 1987 than in 1990. But the globally averaged net cloud radiative forcing was smaller by 0.55W/m2 in 1987 than in 1990. Consequently, the temperature distribution of the oceans has a global effect on atmospheric warming and cooling.