Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Hurricane intensity predictions take into account effect of large eddies on wind speed

10.01.2005


The combined Geophysical Fluid Dynamics Laboratory/University of Rhode Island coupled hurricane-ocean model has helped to improve intensity predictions during tropical storms. However, scientists have found that the model consistently under-predicts maximum wind speed in very strong hurricanes.



In the current issue of the Journal of the Atmospheric Sciences, University of Rhode Island physical oceanographer Dr. Isaac Ginis describes how he and a team of scientists are refining the model by incorporating the factors that favor the formation of large eddies near the sea surface and their effect on wind speed and air humidity. Other members of the team include Alexander P. Khain and Elena Morozovsky of the Institute of Earth Sciences, Hebrew University of Jerusalem, Israel.

The authors speculate that large eddies, or circular currents of air, are a pervasive feature in tropical cyclones and suggests that they can contribute significantly to the transfer of energy, heat, and moisture from the ocean to the atmosphere.


"Lack of adequate consideration of the large eddy effects near the surface of the ocean may be one of the reasons for the limited tropical cyclone intensity forecast skill by hurricane prediction models," said Ginis. "The recently implemented to operational Geophysical Fluid Dynamics Laboratory (GFDL)/ University of Rhode Island (URI) coupled hurricane-ocean model helped to improve the intensity predictions measured by the central pressure. However, it has not always translated into improvements in predicting maximum wind speed. This is mainly due to underestimations of the surface winds in strong tropical cyclones."

In strong wind conditions the GFDL/URI model tends to underpredict surface wind speeds for a given central pressure. It is most likely the result of inadequate representation of the physical processes connected with the storm, in particular the contribution of large eddies in the modeling of the area near the sea surface and how the atmosphere and ocean interact.

The main objective in the study was to investigate the mechanisms leading to the formation of large eddies under tropical cyclone conditions and assess their effects on the factors that determine a storm’s intensity using a high-resolution, atmospheric computer model.

Ginis, Khain, and Morozovsky presented a new method to describe large eddies in both general circulation and regional weather prediction models, including hurricane models. Their approach is called "superparameterization," which consists of an eddy-resolving, two-dimensional system embedded into a weather prediction model, allowing explicit simulations of large eddies.

Based on the results of their numerical simulations, the scientists found that when the wind speed is high enough, a strong vertical wind shear that develops near the sea surface triggers conditions that allow for genesis of large eddies. They concluded that a strong background wind, typical for hurricanes, and evaporation from the ocean are the necessary conditions for the formation of large eddies in the lower part of the atmosphere.

The experiments demonstrated that as soon as large eddies arise, they affect the transport of heat, moisture, and momentum, modifying the structure of the atmosphere and the way it interacts with the ocean. The most significant manifestation of these effects is a significant increase of the near-surface wind speed, and evaporation from the sea surface, which can double in strong winds.

"These results demonstrate the important role that large eddies play in high wind speed conditions," said Ginis. "Inclusion of these effects in the tropical cyclone models may potentially lead to substantial improvements in the prediction of storm intensity."

Ginis’s work on this project was partially supported by the National Science Foundation. Khain and Morozovsky were supported by the Lady Davis Foundation and the U.S.-Israel Binational Science Foundation.

Lisa Cugini | EurekAlert!
Further information:
http://www.gso.uri.edu

More articles from Earth Sciences:

nachricht NASA examines Peru's deadly rainfall
24.03.2017 | NASA/Goddard Space Flight Center

nachricht Steep rise of the Bernese Alps
24.03.2017 | Universität Bern

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>