How this cyclone intensity estimation technique has saved millions of lives across continents

On Tuesday (September 20), American meteorologist Vernon Dvorak died at the age of 100. In the era of advanced satellite technologies, Machine Learning (ML), Artificial Intelligence (AI), this key technique, which bears his name, continues to be widely relied upon by forecasters to this day.

Who was Vernon Dvorak?

Dvorak was an American meteorologist credited with developing the Dvorak (read Do-rak) technique in the early 1970s. The technique has been updated several times since then, and after a recent software update in May this year, it was named Advanced Dvorak Technique (ADT), invented by the National Hurricane Center of the National Oceanic and Atmospheric Administration (NOAA).

The updated technique, US meteorologists had said, would improve tropical storm forecasts by several folds as they would have access to sharper and more detailed images than ever before.

Dvorak was educated at the University of California, Los Angeles. His master’s thesis in 1966 was titled “An Investigation of the Cloud Inversion Regime Over Subtropical Waters West of California”. He has worked with NOAA’s National Environmental Satellite, Data, and Information Service.

This tool, experts say, cannot help make predictions, measure wind or pressure or any other meteorological parameters associated with the cyclone. (Express)

He received the Meritorious Service Award from the United States Department of Commerce in 1972. In 2002, he received a Special Lifetime Achievement Award from the National Weather Association.

What is the Dvorak technique?

It was first developed in 1969 and tested for storm watching in the northwest Pacific Ocean. Forecasters used available satellite imagery obtained from polar-orbiting satellites to examine the characteristics of developing tropical storms (hurricanes, cyclones and typhoons). During the day, images in the visible spectrum were used while at night, the ocean was observed using infrared images.

The Dvorak technique, considered one of the greatest meteorological innovations, has seen several advances since its inception. (Express)

The Dvorak technique was a cloud shape recognition technique based on a conceptual model of tropical cyclone development and decay, according to a 2006 research paper published in the Journal of the American Meteorological Society.

“From the satellite images thus obtained, the Dvorak technique helps forecasters to make pattern recognition from the observed structure of the storm, locate its eye and estimate the intensity of the storm,” said Umasankar Das. , a scientist at the Indian Meteorological Department Center in Bhubaneshwar.

Using this statistical technique, scientists are able to measure the configuration of the convective clouds of the cyclone – curved bands, eye and dense or cold central region and shear. It is the Dvorak technique that gives the best estimates of the intensity of the cyclone, an essential element when issuing weather warnings.

This tool, experts say, cannot help make predictions, measure wind or pressure or any other meteorological parameters associated with the cyclone. But it is a guide to estimating the intensity and possible intensification of the storm – which is crucial for local government in planning evacuation measures for nearby coastal residents or others.

The seasoned meteorologist had also presented the wind speed and associated category of the tropical cyclone, making it an almost perfect tool for operational cyclone forecasters.

Why is the technique still widely used?

Unlike land, ocean sightings in the 1970s were rare.

Today, there is still an improved network of terrestrial weather observations, either in the form of manual observations or by installing automatic weather stations or automatic rain gauges. On the other hand, oceanic observations are still limited. There are many large regions across the four oceans that have not been fully examined with meteorological instruments. Oceanic observations are mainly carried out by the deployment of buoys or dedicated ships, but the number of observations from the seas is still not sufficient throughout the world.

This is why meteorologists have had to rely more on satellite images and combine them with available ocean data when predicting the intensity and wind speed of tropical cyclones.

The Dvorak technique, considered one of the greatest meteorological innovations, has seen several advances since its inception. Even today, when forecasters have access to several advanced tools like model guidance, animations, artificial intelligence, machine learning, and satellite technology, these are the advanced versions of the 50-year-old technique. years that continue to be widely used. It has saved the lives of millions of people around the world and will continue to do so.

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