Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Hurricane Dean tracked from space

22.08.2007
ESA satellites are tracking the path of Hurricane Dean as it rips across the Caribbean Sea carrying winds as high as 260 km per hour. The hurricane, which has already claimed eight lives, is forecast to slam into Mexico’s Yucatan Peninsula on Tuesday morning.

Dean was upgraded early Tuesday to a Category 5 – the highest on the Saffir-Simpson scale – before pummelling the peninsula. Knowing the strength and path of hurricanes is critical for issuing timely warnings; satellites are the best means of providing data on the forces that power the storm, such as cloud structure, wind and wave fields, sea surface temperature and sea surface height.

Instruments aboard ESA’s Envisat and ERS-2 satellites allow them to peer through hurricanes. Envisat carries both optical and radar instruments, enabling researchers to observe high-atmosphere cloud structure and pressure in the visible and infrared spectrum.

Dean off coast of Haiti

The Medium Resolution Imaging Spectrometer (MERIS) optical instrument shows the swirling cloud-tops of a hurricane, while radar instruments such as the Advanced Synthetic Aperture Radar (ASAR) pierce through the clouds to show how the wind fields shape the sea surface and estimate their likely destructive extent.

ERS-2 uses its radar scatterometer to observe the hurricane's underlying wind fields. The scatterometer instrument works by firing a trio of high-frequency radar beams down to the ocean, then analysing the pattern of backscatter reflected up again. Wind-driven ripples on the ocean surface modify the radar backscatter, and as the energy in these ripples increases with wind velocity, backscatter increases as well. Scatterometer results enable measurements of not only wind speed but also direction across the water surface.

What makes ERS-2's scatterometer especially valuable is that its C-band radar frequency is almost unaffected by heavy rain, so it can return useful wind data even from the heart of the fiercest storms.

Winds around eye of Hurricane Dean

Dr. Ad Stoffelen of the Royal Netherlands Meteorological Institute (KNMI), which processes ESA’s scatterometer images, said: "Observed winds from hurricane Dean by ESA's ERS-2 scatterometer are provided to meteorologists within the hour. This C-band radar wavelength scatterometer peeks right into the ‘eye’ of a hurricane like Dean, providing timely and precise information on its position and force.

"The wind field derived from the ESA ERS-2 scatterometer measurements are distributed via a EUMETSAT (European Organisation for the Exploitation of Meteorological Satellites) project to a registered database of a few hundred users, originating from all over the world, such as the Americas, Australia, Asia and Europe. Scatterometer winds are used directly by shift meteorologists in forecast rooms and to initialise Numerical Weather Prediction models aiding the forecasting of hurricanes 5 days ahead."

Dean leaving Martinique

Another Envisat instrument called the Radar Altimeter-2 (RA-2) uses radar pulses to measure sea surface height (SSH) down to an accuracy of a few centimetres. Near-real time radar altimetry is a powerful tool for monitoring a hurricane's progress and predicting its potential impact because anomalies in SSH can be used to identify warmer ocean features such as warm core rings, eddies and currents.

Water temperatures are the main underlying energy reservoir that power hurricanes; together with the correct atmospheric conditions, temperatures need to exceed 26ºC in order to form and maintain a tropical cyclone. Because warm water expands, scientists can locate warm underwater ocean features by detecting bulges in the ocean surface height, as detected by RA-2.

Dean's path and category level

The thermal energy of warm water, which partly powers a hurricane, is known as tropical cyclone heat potential (TCHP). Warm waters may extend to at least 100 meters beneath the surface in many of these oceanic features, representing waters of very high heat content. Several hurricanes have intensified when their tracks pass over eddies or other masses of warm water with high TCHP values.

The US National Oceanic and Atmospheric Administration (NOAA) is utilising Envisat RA-2 results along with those from other space-borne altimeters to chart TCHP and improve the accuracy of hurricane forecasting.

Envisat's Advanced Along Track Scanning Radiometer (AATSR) works like a space-based thermometer, acquiring the temperature of the sea surface down to a fraction of a degree. It also returns useful atmospheric data, measuring the temperature of the top of hurricane clouds – the higher into the atmosphere they extend, the colder they are.

AATSR information can be correlated with MERIS data cloud height and development to gain a good estimate of the hurricane's precipitation potential, and improve understanding of how this relates to its overall intensity. Condensation of water vapour releases latent heat, which warms the vicinity of the hurricane eye. This in turn evaporates more surface water and feeds the heat engine powering the hurricane.

The International Charter 'Space and Major Disasters' has been activated to provide Earth Observation satellite data for assessing the damages of Hurricane Dean in Belize.

Karina De Castris | alfa
Further information:
http://www.esa.int/esaEO/SEM5LLWZK5F_index_0.html

More articles from Earth Sciences:

nachricht Stagnation in the South Pacific Explains Natural CO2 Fluctuations
23.02.2018 | Carl von Ossietzky-Universität Oldenburg

nachricht First evidence of surprising ocean warming around Galápagos corals
22.02.2018 | University of Arizona

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Attoseconds break into atomic interior

A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.

In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...

Im Focus: Good vibrations feel the force

A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.

By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Basque researchers turn light upside down

23.02.2018 | Physics and Astronomy

Finnish research group discovers a new immune system regulator

23.02.2018 | Health and Medicine

Attoseconds break into atomic interior

23.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>