| NSF Org: |
OAC Office of Advanced Cyberinfrastructure (OAC) |
| Recipient: |
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| Initial Amendment Date: | August 18, 2016 |
| Latest Amendment Date: | August 18, 2016 |
| Award Number: | 1614973 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Edward Walker
edwalker@nsf.gov (703)292-4863 OAC Office of Advanced Cyberinfrastructure (OAC) CSE Directorate for Computer and Information Science and Engineering |
| Start Date: | September 1, 2016 |
| End Date: | August 31, 2019 (Estimated) |
| Total Intended Award Amount: | $38,431.00 |
| Total Awarded Amount to Date: | $38,431.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
21 N PARK ST STE 6301 MADISON WI US 53715-1218 (608)262-3822 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
1225 West Dayton Street Madison WI US 53706-1612 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | Leadership-Class Computing |
| Primary Program Source: |
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| Program Reference Code(s): | |
| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.070 |
ABSTRACT
Each year, tornadoes cause millions to billions of dollars of property damage in the United States.
Since 1990, an average of 78 U.S. citizens were killed annually by tornadoes. In
2011, 553 lost their lives from 59 tornadoes out of 1,690 that occurred that year in 48 states.
Despite advances in observational and modeling/computing technology, the
behavior of tornadoes remains a mystery. We are currently unable to predict whether a
given thunderstorm will produce a tornado, much less whether it will be short-lived and weak, or
long-lived and powerful. The proposed work will use Blue Waters to simulate many different violent tornadoes
at resolutions in which the tornado is resolved from its genesis through its dissipation.
By simulating many storms in different environments, the project hopes to identify the factors involved in
the formation and maintenance of the most devastating tornadoes, as well as learn more about its
structure and evolution. This work has the potential to improve the forecasting of the most devastating
storms, ultimately saving lives. Once specific features related to the genesis and maintenance of
long-lived violent tornadoes are identified in simulations on Blue Waters, field researchers can search for
such features in observed storms. Such features identified on operational weather radar could help
forecasters issue specific, targeted warnings for unusually violent tornadoes. Furthermore, modifications
to the code used in the study, CM1, will be shared with the weather modeling community.
In a prior work, the project conducted a breakthrough ultra-high resolution simulation (30 meter grid spacing) on Blue Waters
of a long-lived violent tornado spawned from a supercell that was based upon the observed
24 May 2011 EF5 tornadic supercell in central Oklahoma. The project proposes to build upon this previous work to explore the
sensitivity of tornado morphology in the 24 May 2011 storm to parameters such as cloud microphysics,
turbulence parameterization and low-level environmental wind shear. In addition, the project will enable the use
of arbitrarily stretched vertical grids in CM1 in order to focus resolution at key vertical levels, such
as near the ground. Moreover, the project will apply surface friction in a physically realistic manner, add functionality
to CM1 that enables the centrifuging of rain and hail in regions of intense rotation, and explore
other storm environments in which violent tornadoes occurred. Finally, the project will add the ability for CM1 to
interpolate restart files from a coarser mesh to a finer mesh, allowing the model to simulate periods
of the storm?s life cycle where extreme resolution is focused on the core of storm.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
The Blue Waters supercomputer was used to simulate dozens of supercells (rotating thunderstorms) that produce the world?s strongest tornadoes. Simulations were run using NCAR?s CM1 model with very high spatial and temporal fidelity using different severe storm environments in order to better understand how tornadoes form, and to better understand the physical processes that help maintain violent tornadoes throughout their lifecycle.
Saving high resolution data at such high temporal frequency is a significant unprecedented achievement that will enable years of analysis to be conducted on the data created in this study. To achieve this end, a file system was developed, called LOFS, which uses the self-describing HDF5 scientific data format, and the ZFP lossy floating point compression algorithm which is activated as a plugin to HDF5. This allows data to be stored more efficiently to better utilize available disk space. The LOFS file system, once published, could be used in any field that saves large amounts of data frequently where lossy compression can be applied.
The simulations conducted in this study have identified several features which appear to be important in tornado formation and evolution. The first is the development of many pretornadic small-scale vortices along the boundaries of the storm?s rain-cooled air. The second is a feature we refer to as the streamwise vorticity current (SVC) which is a horizontal tube of rotating air formed within the thunderstorm?s cool outflow air. This horizontal tube is tilted into the vertical and ingested into the lower part of the supercell?s rotating updraft (mesocyclone). The SVC is associated with a significant drop in pressure throughout the bottom 3 kilometers of the mesocyclone which precedes tornado formation, and is often present during the EF4/EF5 phase of the tornado's life cycle. The low pressure associated with the SVC results in a significant increase in the spatial coverage and intensity of updraft winds near the ground. Tornadoes in the simulations develop as a result of the merger and intensification of the pretornadic vortices beneath the strengthening low-level storm updraft.
The discovery of the streamwise vorticity current (SVC) has prompted a new look at the process of tornadogenesis, a process that has been the focus of numerous field studies and numerical simulations. The results of the science conducted in this study, including the discovery in model data of the SVC, were one of the motivations for the NSF sponsored Targeted Observations by Radars and UAS of Supercells (TORUS) field study that is currently under way. The simulation data will also be used in the future for wind engineering studies of tornadoes via a collaboration with wind engineers. Ultimately, it is hoped that this research will help weather forecasters produce better forecasts of severe weather, including increased lead time, highly accurate tornado path forecasts, and fewer false alarms. Should this occur, lives will be saved, benefiting society as a whole.
Last Modified: 12/31/2019
Modified by: Leigh Orf
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