HOME >> MEDICINE >> NEWS
Envisat making first direct measurements of ocean surface velocities

often manifested in SAR images is incomplete," explained Johnny Johannessen of the Nansen Environmental and Remote Sensing Center (NERSC) in Bergen, Norway, who presented results at ESA's SeaSAR 2006 workshop.

But a new light is being shed on these analyses by using neglected extra information embedded in the radar signal: the Doppler shift in electromagnetic waves reflected from the water surface. This shift occurs due to changing relative velocities, experienced in everyday life in the way the pitch of a siren on a passing ambulance goes up as it approaches, then goes down as the vehicle recedes away. This 'Doppler Effect' also serves as the basis of police speed-measuring radar guns.

In this instance, the shift is introduced by the relative motion between the satellite platform, the rotation of the Earth and the velocity of the particular facets of the sea surface from which the SAR signal scatters back to orbit. The initial two values are well known particularly for Envisat, with its very stable satellite orbit and attitude and can be simply subtracted to extract the useful sea surface velocity information.

"This surface velocity, in turn, is composed of contributions from the wind-wave induced motion, and the background surface current," Johannessen added. "Following the Doppler shift equation an estimate of the surface current can be obtained, providing the contributions from wave- and wind-induced motion are first quantified and removed. It is here that the Radar Imaging Model (RIM) comes in."

The RIM is a numerical model that combines outputs from specialised high-resolution ocean models with fundamental equations for SAR imaging of ocean current features and simulate appropriate radar cross section signatures. RIM outputs provide both wave- and wind-induced ocean surface motion for subtraction.

"Our ability to interpret and quantify surface current features imaged by SAR has not been adequately developed," Joha
'"/>

Contact: Mariangela D'Acunto
mariangela.dacunto@esa.int
39-069-418-0856
European Space Agency
27-Mar-2006


Page: 1 2 3 4 5

Related medicine news :

1. European Space Agencys Envisat captures breath of volcano
2. First greenhouse gas animations produced using Envisat SCIAMACHY data
3. ESA donates mosaic of global images taken by Envisat to United Nations
4. Envisat altimeter watches Pacific for cold tongue of La Niña
5. Envisat sees smoke from Europes worst peacetime fire
6. Breath of the dragon: ERS-2 and Envisat reveal impact of economic growth on Chinas air quality
7. Envisat monitoring China floods as part of Dragon Programme
8. Sleep deprivation can threaten competent decision-making
9. Decision making by the growing elderly population is uncharted territory
10. MRI contrast agent can detect heart attack in the making
11. Grace under pressure: FSU researchers analyze the effects of stress on decision-making ability

Post Your Comments:
*Name:
*Comment:
*Email:


(Date:11/14/2018)... (PRWEB) , ... November 14, 2018 , ... The ... the New Year approaches, it’s time to pull out the healthcare plan paperwork to ... self-purchased plan or sponsored by an employer, most people can benefit by taking a ...
(Date:11/13/2018)... ... November 13, 2018 , ... A survey by the publishers of ADC ... for antibody therapies reached U.S. $ 4 billion. Approximately forty-five percent of this market ... antibody therapies (including ADCs) is expected to grow significantly, to U.S. $ 17 billion ...
(Date:11/13/2018)... , ... November 13, 2018 , ... ... the insurance industry is working around the clock to help policyholders through the ... safety of its customers,” said Katie Pettibone, vice president of state affairs, western ...
(Date:11/13/2018)... ... November 13, 2018 , ... Researchers at ... Global Research and Acoustic MedSystems Inc., have received a five-year, $3.5 million award ... Academic-Industrial Partnership program, to continue development of an innovative robotic system that, operating ...
(Date:11/13/2018)... ... November 13, 2018 , ... Beaumont Solar, a leading, ... has been named to Boston Business Journal’s (BBJ) annual list of the ... This time, Beaumont Solar, through significant growth, secured the 8th position among the ...
Breaking Medicine News(10 mins):
(Date:11/13/2018)... ... November 13, 2018 , ... Mount Sinai ... development collaborator, had completed a public listing that valued the company at $85 ... raised $29 million from a syndicate of health care institutional and industry investors, ...
(Date:11/13/2018)... ... November 13, 2018 , ... The Healthcare Linen Alliance is ... development and partnerships. Rick has spent much of his career in the commercial ... Sales, Rick brings his extensive background in the industry to the team. , ...
(Date:11/13/2018)... ... November 13, 2018 , ... Loyale Healthcare ... Sykes will concentrate on larger healthcare enterprises, where Loyale’s Patient Financial Manager™ has ... improved, integrated patient experiences. , Mr. Sykes’ distinguished healthcare career includes more ...
Breaking Medicine Technology:
Cached News: