Generalized Barotropic Models for Studying the Low -Frequency Variability of the Extratropical Atmosphere

119 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2003.Finally, the generalized model is scrutinized in terms of its normal, adjoint, optimal and singular modes. It is found that the modes of the empirically modified model are more stable than the ones of the barotropic model. Also the modified barotropic optimal modes are more difficult to excite than their barotropic counterparts. These results are in accordance with previous studies that found that barotropic dynamics may not quantitatively describe LFV. The singular modes of the modified operator have very similar patterns but explain less variance than the barotropic ones. This is consistent with the difficulty in detecting optimal patterns in observations. Finally, we find that the modified barotropic operator is more normal than the classic barotropic one, and thus less variable.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Recent behavior of the Hadley cell and tropical thermodynamics in climate models and reanalyses

The behavior of the Hadley cell and the thermodynamic structure of the tropical atmosphere is analyzed over the period 1979–2000 in climate models and reanalyses. Significant trends in the strength of the Hadley cell are present in reanalyses that are not reproduced by models. Analysis of the thermodynamic structure also shows significant discrepancies between models and reanalyses, the former show warming aloft and increased static stability while the latter show a cooling trend and decreased static stability in the tropical mid‐troposphere. Additional energy balance analysis reveals that models and reanalyses have a fundamentally different balance between diabatic heating, circulation and thermodynamic structure over the period 1979–2000. Uncertainties in the observations of tropospheric temperatures as well as potential biases and errors in the climate models raise questions about the true long‐term behavior of the thermodynamic structure of the tropical troposphere and the Hadley cell

Has the Hadley cell been strengthening in recent decades?

The intensity and structure of the Northern Hemisphere DJF Hadley cell as depicted in various commonly used data sets are examined. We find that the NCEP/NCAR and ECMWF reanalyses show a statistically significant intensification of their Hadley circulation throughout their periods. In marked contrast the NCEP‐DOE reanalysis does not show any discernible trend over its period. Furthermore, the Hadley cell structure differs substantially from the other two reanalyses. We also examine a data set of global rawinsonde observations in which the Hadley cell shows no intensification. Finally, we investigate the Hadley cell simulated by an atmospheric GCM. The ensemble mean shows a statistically significant intensification, though it is smaller in magnitude than the reanalyses. We conclude that the two major reanalyses appear to be in agreement on the strengthening of the Hadley cell in recent decades. However, discrepancies among data sets do raise questions about the robustness of this strengthening

From Scilab to Multicore Embedded Systems: Algorithms and Methodologies

International audienc

From Scilab to Multicore Embedded Systems: Algorithms and Methodologies

International audienc

Mapping embedded applications on MPSoCs: The MNEMEE approach

As embedded systems are becoming the center of our digital life, system design becomes progressively harder. The integration of multiple features on devices with limited resources requires careful and exhaustive exploration of the design search space in order to efficiently map modern applications to an embedded multi-processor platform. The MNEMEE project addresses this challenge by offering a unique integrated tool flow that performs source-to-source transformations to automatically optimize the original source code and map it on the target platform. The optimizations aim at reducing the number of memory accesses and the required memory storage of both dynamically and statically allocated data. Furthermore, the MNEMEE tool flow parallelizes the application's source code and performs optimal assignment of all data on the memory hierarchy of the target platform. Designers can use the whole flow or a part of it and integrate it into their own design flow. This work gives an overview of the MNEMEE tool flow. It also presents two industrial case studies that demonstrate how the techniques and tools developed in the MNEMEE project can be integrated into industrial design flows

Mapping embedded applications on MPSoCs:The MNEMEE approach

\u3cp\u3eAs embedded systems are becoming the center of our digital life, system design becomes progressively harder. The integration of multiple features on devices with limited resources requires careful and exhaustive exploration of the design search space in order to efficiently map modern applications to an embedded multi-processor platform. The MNEMEE project addresses this challenge by offering a unique integrated tool flow that performs source-to-source transformations to automatically optimize the original source code and map it on the target platform. The optimizations aim at reducing the number of memory accesses and the required memory storage of both dynamically and statically allocated data. Furthermore, the MNEMEE tool flow parallelizes the application's source code and performs optimal assignment of all data on the memory hierarchy of the target platform. Designers can use the whole flow or a part of it and integrate it into their own design flow. This work gives an overview of the MNEMEE tool flow. It also presents two industrial case studies that demonstrate how the techniques and tools developed in the MNEMEE project can be integrated into industrial design flows.\u3c/p\u3

From Scilab To High Performance Embedded Multicore Systems - The ALMA Approach

International audienc

From Scilab To High Performance Embedded Multicore Systems - The ALMA Approach

International audienc