Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Envisat sees whirling Hurricane Katrina from ocean waves to cloud tops

30.08.2005


ESA’s multi-sensor Envisat satellite has gathered a unique view of Hurricane Katrina in the Gulf of Mexico. While an optical image shows characteristic spiralling cloud patterns, a simultaneous radar observation pierces through the clouds to show how Katrina’s 250-kilometre-an-hour an hour winds scour the sea surface.



Envisat simultaneously acquired these images at 1550 UTC (1150 US Eastern Daylight Saving Time) on 28 August, with its Medium Resolution Imaging Spectrometer (MERIS) and Advanced Synthetic Aperture Radar (ASAR).

At the time of acquisition Hurricane Katrina was a maximum Category Five on the Saffir-Simpson scale. Further ESA acquisitions are being prioritised because the International Charter on Space and Major Disasters has been activated.


The eye of the hurricane is seen clearly in both images, with the wall of the eye clearly visible in the MERIS image, the area of the hurricane where the fastest winds and highest rainfall is found.

The ASAR instrument works by recording signal backscatter based on surface roughness: the wind-free storm centre – seen enclosed within a dark ring feature measuring approximately 60 kilometres across - shows up darker because the waters here are hardly rippled by comparison to the sea around it.

Hurricane Katrina, which formed in the Bahamas in mid-August, struck South Florida on 25 August, killing nine people and leaving a million more without electricity. It is poised to strike coastal Louisiana and New Orleans. Hurricane-strength winds of at least 119 kilometres per hour currently extend 136 kilometres from its centre.

Katrina has today dropped from a maximum Category Five to a Category Four storm on the Saffir-Simpson scale, but forecasters warn it could again grow in intensity having made landfall.

With serious flooding anticipated in the hurricane’s wake as well as direct storm damage, the US Geological Service (USGS) activated the International Charter on Space and Major Disasters on 27 August.

ESA is a founding member of the Charter, which represents a joint effort by global space agencies to put resources at the service of rescue authorities responding to major natural or man-made disasters. To date the Charter has been activated more than 80 times.

Observing hurricanes

A hurricane is basically a large, powerful storm centred around a zone of extreme low pressure. Strong low-level surface winds and bands of intense precipitation combine strong updrafts and outflows of moist air at higher altitudes, with energy released as rainy thunderstorms.

Envisat carries both optical and radar instruments, enabling researchers to observe high-atmosphere cloud structure and pressure in the visible and infrared spectrum, while at the same time using radar backscatter to measure the roughness of the sea surface and so derive the wind fields just above it.

Those winds converging on the low-pressure eye of the storm are what ultimately determine the spiralling cloud patterns that are characteristic of a hurricane.

Additionally Envisat instruments can potentially be used to take the temperature of the warm ocean waters that power storms during the annual Atlantic hurricane season, or detect sea height anomalies related to warm upper ocean features known as ’loop currents’.

Mariangela D’Acunto | alfa
Further information:
http://www.esa.int/esaEO/SEMB41A5QCE_environment_0.html

More articles from Ecology, The Environment and Conservation:

nachricht Waste in the water – New purification techniques for healthier aquatic ecosystems
24.07.2018 | Eberhard Karls Universität Tübingen

nachricht Plenty of habitat for bears in Europe
24.07.2018 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

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

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Smallest transistor worldwide switches current with a single atom in solid electrolyte

17.08.2018 | Physics and Astronomy

Robots as Tools and Partners in Rehabilitation

17.08.2018 | Information Technology

Climate Impact Research in Hannover: Small Plants against Large Waves

17.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>