Archive | June 2013

Featured Storm – Cyclone Alibera (1989)

Very Intense Cyclone Alibera

Citizen scientists working at Cyclone Center now have four storms to choose from when they sign in to classify.  Our first set of storms includes Cyclone Alibera, a long-lasting Southern Indian Ocean storm that thrashed coastal Madagascar on New Years Day 1990.

The path the Cyclone Alibera followed

The path the Cyclone Alibera followed during the first 3 weeks of its life.  The storm formed in the upper right portion of the map and moved toward the lower left.

Alibera formed in the Indian Ocean on December 14, 1989 and did not dissipate until January 7, 1990 – a whopping 25 days!  During that time, the storm traveled several thousand kilometers, which included a big loop.  Cyclones like Alibera are steered by the large-scale winds in the atmosphere.  Sometimes when these winds are weak and/or changing, storms can move in strange ways.  The first image shows the long and interesting track of Alibera.

During the second week of Alibera’s life, the atmospheric and ocean conditions became very favorable for intensification.  The storm rapidly strengthened from a subdued tropical storm into a minor or very intense tropical cyclone, depending on who you believe.

Two forecast centers tracked Alibera during this time.  The Joint Typhoon Warning Center, or JTWC, is a U.S. Navy and Air Force office in Hawaii that monitors the western Pacific and Indian Oceans.  Based on imagery like those that citizen scientists are analyzing in Cyclone Center, analysts determined that Alibera was a “Very Intense Cyclone”, with wind speeds on the threshold of Category 5 intensity in the Saffir-Simpson scale.   However, analysts at a French forecast centre on La Reunion, an island off the east coast of Madagascar, determined that Alibera was only a minimal Category 1 tropical cyclone at the same time.  The figure below shows that these differences in opinion were not limited to the time of Alibera’s strongest intensity.

Alibera best track intensities

Alibera intensities as determined by JTWC and Reunion forecast centers.

This is why Alibera is one of the first storms that we would like citizen scientists to analyze.  We want to know what YOU think Alibera’s intensity was – we will use this information to reconcile these big differences.

Alibera eventually would make landfall in coastal Madagascar on New Year’s day, killing 46 people.  Though not widely known outside of the southern Indian Ocean region, Alibera is certainly a storm worthy of our attention – and a good example of how tropical cyclone forecasters can wildly disagree on a storm’s intensity when observations are not available.

Log on to Cyclone Center today and classify Alibera.

– Chris Hennon is part of the Cyclone Center Science Team and Associate Professor of Atmospheric Sciences at the University of North Carolina at Asheville

Advertisements

A Better Cyclone Center

Cyclone Center has recorded over 210,000 classifications from citizen scientists around the world since its launch in September 2012.  But we’re not resting on our laurels; the site has undergone significant changes that we think will make your experience classifying storms even  more rewarding. Highlights of the new site include:

1. Targeted storm choices.  Choose your favorite storm to classify from a list of four storms that we’d like you to focus on.  These storms will change frequently as you help us complete each one.  Featured in the early sets of storms will be at least one storm from the historic 2005 Atlantic hurricane season, including Hurricanes Katrina and Wilma.  Or, if you’re feeling adventurous, click the “Classify a random storm” button and get a mystery storm!

New selection menu for Cyclone Center

New selection menu for Cyclone Center

2. Inline classification guidance.  Gone are the days of clicking on question marks to get help.  For each step in the process, you will be shown information on how to best answer the question.  Even though you have been doing great, we think this will give you more confidence in what you are doing and hopefully inspire you to do more!

3. Improved tutorial.  Haven’t classified in a few weeks?  Now you can access our improved tutorial at any time for a refresher.

4. More questions to answer.  For each storm, go beyond the “choose the closest picture” to answer a couple of more questions like where the center of the storm is or how cold the clouds are around the eye.  This used to be called “Detailed Classification”; your responses help us to better pinpoint how strong the storms are.

5. Real time feedback on your classification.  Now instead of waiting for 6 images to see the “Storm Stats” page, you will immediately go there after your first image.  Now available on this much improved page is the storm track, the location of the storm you just classified, and our estimate of the wind speed of the storm based on your answers.  

Real time feedback

Real time feedback on your work is now given after each image

6. Upgraded Talk forum.  “Talk” is how you can discuss interesting storms with others or us.  The upgraded version allows for better searching and highlights more of the interesting discussions going on between other citizen scientists.

7. Better connections to social media.  Direct links to Facebook and Twitter are now available on every storm on the home page.  Click and discuss storms with your social communities or invite others to participate!

Log in to Cyclone Center today and give the new version a try – we think you’ll like the changes.  As always, please let us know what you think by commenting on this blog entry or through Talk!

– Chris Hennon is part of the Cyclone Center Science Team and Associate Professor of Atmospheric Sciences at the University of North Carolina at Asheville