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Marine Ecosystems Research Department - jamstec japan agency ...

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Japan <strong>Marine</strong> Science and Technology Center<br />

Frontier <strong>Research</strong> System for Global Change<br />

provide realistic initial conditions for adequate prediction<br />

and also useful re-analysis datasets for accurate<br />

estimation of ocean circulation processes.<br />

a. Coupled Model Development<br />

a-. Future Climate Change Projection Using a High-<br />

Resolution Coupled Ocean-Atmosphere Climate<br />

Model<br />

The aim of this project is to conduct a series of future<br />

climate change projection experiments using a high-resolution<br />

coupled ocean-atmosphere climate model on the<br />

Earth Simulator. The project team consists of members<br />

of Center for Climate System <strong>Research</strong> of the<br />

University of Tokyo (CCSR), National Institute for<br />

Environmental Studies (NIES), and Frontier <strong>Research</strong><br />

System for Global Change (FRSGC).<br />

For the high-resolution future climate change projection,<br />

we have targeted the following spatial resolution<br />

of the model:<br />

<br />

T spectral truncation (approximately .˚) in horizontal<br />

and levels in vertical for the atmospheric part<br />

<br />

.˚ .˚ in horizontal and levels in vertical<br />

for the oceanic and sea-ice part<br />

With this atmospheric resolution, regional-scale climatic<br />

features such as Baiu front and tropical cyclones<br />

can be represented. The oceanic resolution should be<br />

higher so that the model can reproduce realistic temporal<br />

variation of sea-surface height and the complex ocean<br />

current system in the northern North Atlantic and the<br />

Arctic Oceans, which is critically important to reproduce<br />

the North Atlantic Deep Water (NADW) realistically.<br />

Further details are referred to the report of the project<br />

in this volume.<br />

a-. Improvement of Physical Processes in Climate<br />

Models<br />

(i) Development of new radiation scheme<br />

So far there has been no unique method applicable<br />

to treat any overlapping of bands on radiative transfer<br />

calculation when we require both high accuracy and<br />

computational efficiency. After examining several possible<br />

schemes, it is found that only one scheme is not<br />

sufficient to treat all overlapping bands with the same<br />

accuracy. Therefore we develop an optimized scheme<br />

to obtain k-distribution parameters for overlapping<br />

bands by combining completely uncorrelated, perfectly<br />

correlated and partly correlated schemes.<br />

By use of this newly developed scheme, calculations<br />

of radiative flux and atmospheric heating/cooling rate<br />

were performed and the results were compared with<br />

corresponding results of the LBL calculations for six<br />

model atmospheres (Tropical, Midlatitude summer and<br />

winter, Subarctic summer and winter and the US<br />

Standard Atmosphere). The results are shown in Fig.<br />

P (mb)<br />

0.1<br />

1<br />

10<br />

1E+2<br />

a<br />

TRO<br />

CKD<br />

LBL<br />

Error<br />

1E+3<br />

-12.0 -8.0 -4.0 0.0 4.0<br />

Heating Rate (K/d)<br />

P (mb)<br />

0.1<br />

1<br />

10<br />

1E+2<br />

c<br />

CKD<br />

LBL<br />

Error<br />

CKD<br />

LBL<br />

Error<br />

-0.2 0.2<br />

-0.4 0.0 0.4<br />

Error (K/d)<br />

1E+3<br />

-12.0 -8.0 -4.0 0.0<br />

Heating Rate (K/d)<br />

P (mb)<br />

0.1<br />

1<br />

10<br />

1E+2<br />

e<br />

MLW<br />

SAW<br />

1E+3<br />

-12.0 -8.0 -4.0 0.0<br />

Heating Rate (K/d)<br />

P (mb)<br />

0.1<br />

1<br />

10<br />

1E+2<br />

1E+3<br />

b<br />

P (mb)<br />

0.1<br />

1<br />

10<br />

1E+2<br />

d<br />

MLS<br />

CKD<br />

LBL<br />

Error<br />

-12.0 -8.0 -4.0 0.0<br />

Heating Rate (K/d)<br />

CKD<br />

LBL<br />

Error<br />

CKD<br />

LBL<br />

Error<br />

-0.2 0.2<br />

-0.4 0.0 0.4<br />

Error (K/d)<br />

1E+3<br />

-12.0 -8.0 -4.0 0.0<br />

Heating Rate (K/d)<br />

-0.2 0.2<br />

-0.4 0.0 0.4 -0.2 0.2<br />

-0.4 0.0 0.4<br />

Error (K/d)<br />

Error (K/d)<br />

-0.2 0.2<br />

-0.4 0.0 0.4<br />

Error (K/d)<br />

P (mb)<br />

0.1<br />

1<br />

10<br />

1E+2<br />

1E+3<br />

f<br />

SAS<br />

USS<br />

-12.0 -8.0 -4.0 0.0<br />

Heating Rate (K/d)<br />

-0.2 0.2<br />

-0.4 0.0 0.4<br />

Error (K/d)<br />

Fig.18 The comparison of heating rates for four transmission<br />

schemes to those of LBL model. Black solid line represents<br />

LBL results; the dashed lines with different colors<br />

represent errors of the four schemes to LBL results. (a)<br />

H 2 O, CO 2 and O 3 (630-700cm -1 ); (b) H 2 O, N 2 O and CH 4<br />

(1200-1350cm -1 ); (c) H 2 O, CO 2 and O 3 (940-1200cm -1 ); (d)<br />

H 2 O and CH 4 (3900-4540cm -1 ).<br />

135

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