What Caused the Rapid Intensification of Super Typhoon Haiyan?

Typhoon Haiyan at peak intensity on November 7, 2013. Credit: NASA

Typhoon Haiyan at peak intensity on November 7, 2013. Credit: NASA

During the AMS Hurricane and Tropical Meteorology meeting in San Diego last week, Rosenstiel School professor Nick Shay presented research on the role ocean warming played in the rapid intensification of last year’s devastating Super Typhoon Haiyan in Southeast Asia.

Shay’s study suggests that temperature fluctuations from semi-diurnal internal tides need to be analyzed to fully understand the causes of rapid intensification as the storm went over the warm pool of water in the western Pacific prior to landfall in the Philippines.

Using temperature, salinity and current data collected as Haiyan made a direct hit over the Japan’s Triton buoy (formerly a NOAA TAO buoy), along with satellite-derived data from the SPORTS climatology model (Systematically merged Pacific Ocean Temperature and Salinity developed by Rosenstiel School graduate student Claire McCaskill), Shay’s research team examined ocean warming conditions prior to Haiyan at the thermocline, a distinct ocean temperature layer that is known to fluctuate seasonally due to tides and currents.

 

infrared satellite loop of Typhoon Haiyan in the Philippines. Credit: NOAA

infrared satellite loop of Typhoon Haiyan in the Philippines. Credit: NOAA

Internal tides are known to create large temperature fluctuations. Shay suggests that the upper ocean heat content was important in the rapid intensification of Haiyan similar to what is observed in the Atlantic Ocean basin. While the semidiurnal tides were amplified in the warming thermocline in this regime, they have to be removed from the data to accurately evaluate questions related to the roles climate change and oceanic warming played in the storm’s intensification.

At the Heart of a Hurricane Forecast

One of the many challenges in hurricane forecasting is incorporating observational data into forecast models. Data assimilation, as scientists refer to it, is the process of combining observational data – information obtained by satellites, radars or from instruments deployed into storms by aircraft – into a numerical weather prediction model.

Incorporating real-world temperature, wind, moisture or atmospheric pressure from multiple sources is a core component of hurricane science and vital to provide improved forecasts of both the track and intensity of storms. How to incorporate new types of observational information into a model is at the very heart of hurricane forecasting.

At the American Meteorology Society’s 31st annual Hurricane and Tropical Meteorology meeting in San Diego this week, Rosenstiel School Professor Sharan Majumdar discussed new approaches to improve data assimilation.

Typhoon Sinlaku (2008), as seen from Terra Satellite on September 10 2008. Credit: NASA

Typhoon Sinlaku (2008), as seen from Terra Satellite on September 10 2008. Credit: NASA

Citing the Ph.D. research of Rosenstiel School graduate student Ting-Chi Wu, Majumdar discussed the assimilation of temperature and moisture data obtained from satellite-based advanced Infrared (IR) soundings measured by polar-orbiting satellites of Typhoon Sinlaku during the 2008 Pacific typhoon season. Wu’s studied the period of storm intensification as Sinlaku intensified into a category-2 typhoon. Her conclusion was that the assimilation of temperature and moisture show promise in improving forecasts of hurricane and typhoon intensity, though more work needs to be done to improve their use.

Majumdar also provided an overview of strategies to assimilate observations to improve numerical weather forecasts of the track and structure of storms. He showed that targeted aircraft observations in select areas and satellite observations from both within and outside a tropical cyclone are beneficial.

CARTHE Air & Ocean Photo Contest

Do you often see incredible natural phenomena appearing on the sea surface or sky? Snap a picture of it and you can win cool gear from CARTHE – The Consortium for Advanced Research on Transport of Hydrocarbons in the Environment.

To participate in the CARTHE Air & Ocean Photo Contest, simply observe nature, capture its beauty, and share it! For example, the various “textures” of the sea surface with different wind conditions, accumulation of sea weed and other debris along lines parallel to the wind, strong contrast in colors and sea texture at river inlets, and dynamic air-sea interactions. For more information, visit the CARTHE website.

IMG_8204Here are the rules:

Entry Rules

  • Images can be of the ocean, coastal water systems, inland water systems, or air/atmospheric systems.
  • The CARTHE Photography Contest is open to all amateur photographers. Amateur photographers are those who earn no more than 20% of their income from their photography. Eligible photos are those that have not been published or accepted for publication and must have been taken by the person submitting the entry. The Photographer must have ownership and copyright of all entries.
  • All photographs must be taken in a natural fresh-water or salt-water environment.
  • Digital editing of photographs is acceptable in moderation. Only minor adjustments will be accepted (ie. minor brightness, contrast, or cropping). Any heavily filtered or manipulated photograph will be rejected at judges’ discretion.
  • Ownership and copyright of all entries remain with the photographer. CARTHE, GoMRI, and RSMAS reserves the right to publish the winning photos without compensation for educational purposes, including, but not limited to publication on the CARTHE/GoMRI/University of Miami/RSMAS websites, social media, in brochures or for future contest promotion. Proper credit will be given to all winners.
  • By submitting your images, you are agreeing to the terms above.

Snap away and good luck!

Explore CARTHE’s Award-Winning Website

The University of Miami was awarded two Outstanding Achievement awards by the Interactive Media Council for excellence in the design, development and implementation of the CARTHE website. Based at the UM Rosenstiel School, the Consortium for Advanced Research on Transport of Hydrocarbon in the Environment (CARTHE) is a research team dedicated to predicting the fate of the oil released into our environment as a result of future oil spills.

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The CARTHE website launched in August 2013 and serves as a web portal devoted to interactive information and science education for scientists, students, members of the press and the general public. The CARTHE website was created in collaboration with Professor Kim Grinfeder and his team from the UM School of Communications.

“The idea of this website was conceived when I met Kim Grinfeder from the School of Communication at a workshop I attended on main campus,” said Tamay Özgökmen, CARTHE director and Rosenstiel School professor.

“We needed an interactive website to tell our complex scientific story.  Over the course of the next few months, we conceived the website, which had two main interactive elements: An interactive infographic through which visitors can get information about the project, and a main introductory video on the homepage,” said Professor Özgökmen.

The CARTHE videos were developed by Ali Habashi, faculty member in the UM School of Communication’s Department of Cinema and Interactive Media.

“Ali was recommended to me by three different, unrelated people within a week. His name came up repeatedly when I said that it would be most efficient to have a video to tell our complex scientific story within the time span of a few minutes;  people would say “Will Ali do it?” He has a great reputation within the UM community and beyond,” said Professor Özgökmen.

“What I liked most about this project was its cross-disciplinary aspect and how it really shows how different areas of UM can collaborate,” said Kim Grinfeder, associate professor in the UM Department of Cinema and Interactive Media. “CARTHE is an amazing project happening at our university and to learn about their work and to have the opportunity to tell their story was an incredible experience.”

“There are plenty of benefits that can come from bringing faculty members from different schools together, and the CARTHE website is one example,” said Professor Özgökmen.

The judging consisted of various criteria, including design, usability, innovation in technical features, standards compliance and content. The website won in two categories, Science/Technology and Natural Environment/Green. It has received 4,583 visits since its launch in August 2013.

For more information about CARTHE, please visit www.carthe.org or on Facebook at www.Facebook.com/carthe.gomri.

– RSMAS Communications 

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Hurricane Intensity Study Wins ‘Outstanding Poster’ Award

UM Rosenstiel School Meteorology and Physical Oceanography graduate student Falko Judt was awarded first prize in the Outstanding Student Poster competition at the American Meteorology Society’s 94th Annual Meeting in Atlanta, Georgia. Falko shares the research behind his poster, titled “Tropical Cyclone Intensity Forecasting: Predictability and Uncertainty.”

MPO Graduate Student Falko Judt

MPO Graduate Student Falko Judt

“The main goal of my research is to better understand and therefore better predict the intensity of hurricanes. Computer model forecasts are getting better with forecasting where a hurricane will go (its track), but we’re still having a hard time telling in advance how strong a storm might become (intensity).

One school of thought is that it is very difficult to accurately forecast intensity for more than 2 days because small-scale and not well understood processes in the inner regions of a storm. In the inner core, energy from the ocean surface is converted to strong winds in thunderstorm clouds that surround the eye, forming the hurricane rain bands. Knowing the exact arrangements and processes going on in these clouds is, according to this hypothesis, very important for forecasting changes in a hurricane’s intensity.

On the other hand, some scientist argue that these small-scale processes going on within the hurricane don’t matter too much, and the really important factors determining the strength of a storm are properties of the large-scale environment surrounding it. For example, high ocean temperatures, high atmospheric humidity values and low wind shear are known to lead to intensification of hurricanes.

My research was testing these hypotheses by adding stochastic (random) perturbations to state-of-the-art computer models (ensemble forecasts) predicting the intensity of Hurricane Earl of 2010, which is a storm that already happened, so we can compare the forecasts to what was observed.

In one ensemble, tiny perturbations with the size of clouds were added to the model, and another ensemble had larger perturbations on the scale of real weather systems — about a few hundred to thousands of miles. We found that very small perturbations do not change the properties of the hurricane predictions, and even larger-scale perturbations only cause some fluctuations in their forecasted intensity.

We therefore concluded that ultimately the environmental conditions determine how strong a storm will be. This is good news because we have better knowledge about and data from a hurricane’s environment.

Based on this research presented in my poster, we might even be able to tell how strong a storm will become 7 day in advance with the help of improving computer models and better observations from the surrounding atmosphere. The predictability limit seems to be longer than what had been expected.”

– Falko Judt