NO JAVASCRIPT

This website requires JavaScript to function properly / Ce site a besoin de JavaScript pour fonctionner correctement

Aviso+
News
Image of the month
2011
Jul. 2011: Altimetry peaks at sea ice

Altimetry peaks at sea ice

Image of the Month - July 2011

Sea ice cover deduced from altimetry echo shapes for the austral winter of 2009 and 2010 (yellow sea ice cover for both winters, red only 2009, blue only for 2010). For comparison an indication of scatterometer measurements is given for 2009, which is matching quite well with the altimetry-deduced sea ice cover for the same year. (Credits ISRO/SAC)

Antarctica is a frozen continent. However, sea ice around it mostly forms and melts each year, since the Southern Ocean that surrounds it is open (contrary to the Arctic Ocean, enclosed by lands). Variations occur from one year to the other, with impacts on iceberg sheddings, marine animals... However, the Southern Ocean is not a place where a ship can safely navigate and easily take measurements, even when the ocean is ice-free. It is next to impossible in the core of the Austral winter. So satellites are the only way of really monitoring ice cover around Antarctica.

Altimetry can observe sea ice in different ways. We already wrote about some of them. Today is still another one. Altimeter radar waves do not bounce back in the same way over water or ice. When the waves are bouncing on ice, the echoes are much "peakier" than over water. A parameter can be included in altimetry data that measures this "peakiness'. Thus when such peaky echoes are encountered over ocean, it is a sign that there is sea ice rather than water.

Jason-2 has been measuring the sea surface height, and incidentally a number of other parameters, for three years now. With the future Saral mission and the AltiKa altimeter onboard, other information will be added, and the time series continued.

Reference:

S. R. Oza , M. K. Dash, R. K. K. Singh, A. Shrivastav, I. M. L. Das and N. K. Vyas, 2011, Investigations of the inter-annual variations of polar Ice surface characteristics using altimetric observations , AltiKa Science Workshop, March 2011, Ahmedabad, India.

News

Search.
Front-page news.
Image of the month .
- 2024 .
- 2023 .
- 2022 .
- 2021 .
- 2020 .
- 2019 .
- 2018 .
- 2017 .
- 2016 .
- 2015 .
- 2014 .
- 2013 .
- 2012 .
- 2011 .
  - Dec. 2011: Missing: water.
  - Nov. 2011: the ocean is (in part) its own source of variability.
  - Oct. 2011: Crustaceans off Chile.
  - Sep. 2011: Cold and warm eddies pair off Vietnam.
  - Aug. 2011: Southern swell.
  - Jul. 2011: Altimetry peaks at sea ice.
  - June 2011: Extreme wave heights.
  - May 2011: Between Africa and Madagascar.
  - Apr. 2011: Routing ships with the currents.
  - Mar. 2011: 177,000 eddies in the oceans.
  - Feb. 2011: "Lively currents" plus ten years.
  - Jan. 2011: La Niña's in turn to wreak havoc .
- 2010 .
- 2009 .
- 2008 .
- 2007 .
- 2006 .
- 2005 .
- 2004 .
- 2003 .
- 2002 .
- 2001 .
- 2000 .
- 1999 .
- 1998 .
Press review.
Operational news and status .
News from CTOH .
Events calendar.

Customizable homepage

This home page is composed of blocks called "widgets".

Rearrange the blocks with a "Click & Drop".

Hide a widget with the cross at the top right. Reset or add a widget with the "wrench" icon. The "User" and "Public" profiles offer a predefined organization.

All the modifications are automatically saved as cookies on your machine so as to enable you to have your own specific AVISO+.

Browsing menu and breadcrum trail

To ease your browsing through AVISO+, you can use at any time the main banner items with the interactive submenus or use the browsing menu on the left side of the screen (it is open by default). For more readiness of the page contents, you can fold and unfold the browsing menu by clicking on the tab. At any time you can know where you are thanks to the browsing menu or the breadcrum at the top of the page.