Providing reliable estimates of possible anthropogenic climate change is the subject of considerable scientific effort in the climate modeling community. Climate model simulations are computationally very intensive and the necessary computing capabilities can be provided by supercomputers only. Although modern high performance computer platforms can deliver a peak performance in the Petaflop/s range, most of the existing Earth System Models (ESMs) are unable to exploit this power. The main bottlenecks are the single core code performance, the communication overhead, non-parallel code sections, in particular serial I/O, and the static and dynamic load imbalance between model partitions. The pure scalability of ESMs on massively parallel systems has become a major problem in recent years. In this study we present results from the performance and scalability analysis of the high-resolution ocean model MPIOM and the atmosphere model ECHAM6 on the largescale multicore cluster ”Blizzard” located at the German Climate Computing Center (DKRZ). The issues outlined here are common to many currently existing ESMs running on massively parallel computer platforms with distributed memory.

@inproceedings{PCOGHOAAMO11,
	author	 = {Panagiotis Adamidis and Irina Fast and Thomas Ludwig},
	title	 = {{Performance Characteristics of Global High-Resolution Ocean (MPIOM) and Atmosphere (ECHAM6) Models on Large-Scale Multicore Cluster}},
	year	 = {2011},
	booktitle	 = {{Parallel Computing Technologies - 11th International Conference, PaCT 2011, Kazan, Russia, September 19-23, 2011. Proceedings}},
	editor	 = {Victor Malyshkin},
	publisher	 = {Springer},
	series	 = {Lecture Notes in Computer Science},
	number	 = {6873},
	pages	 = {390--403},
	conference	 = {PaCT},
	location	 = {Kazan, Russia},
	isbn	 = {978-3-642-23177-3},
	doi	 = {http://dx.doi.org/10.1007/978-3-642-23178-0},
	abstract	 = {Providing reliable estimates of possible anthropogenic climate
change is the subject of considerable scientific effort in the climate
modeling community. Climate model simulations are computationally
very intensive and the necessary computing capabilities can be provided
by supercomputers only. Although modern high performance computer
platforms can deliver a peak performance in the Petaflop/s range, most
of the existing Earth System Models (ESMs) are unable to exploit this
power. The main bottlenecks are the single core code performance, the
communication overhead, non-parallel code sections, in particular serial
I/O, and the static and dynamic load imbalance between model partitions.
The pure scalability of ESMs on massively parallel systems has
become a major problem in recent years. In this study we present results
from the performance and scalability analysis of the high-resolution
ocean model MPIOM and the atmosphere model ECHAM6 on the largescale
multicore cluster ”Blizzard” located at the German Climate Computing
Center (DKRZ). The issues outlined here are common to many
currently existing ESMs running on massively parallel computer platforms
with distributed memory.},
	url	 = {http://www.springerlink.com/content/978-3-642-23177-3/#section=956636&page=1&locus=0},
}