Subscribe free to our newsletters via your
. 24/7 Space News .




EARTH OBSERVATION
NASA Satellites Detect Pothole on Road to Higher Seas
by Staff Writers
Pasadena CA (JPL) Aug 24, 2011


The red line in this image shows the long-term increase in global sea level since satellite altimeters began measuring it in the early 1990s. Since then, sea level has risen by a little more than an inch each decade, or about 3 millimeters per year. While most years have recorded a rise in global sea level, the recent drop of nearly a quarter of an inch, or half a centimeter, is attributable to the switch from El Nino to La Nina conditions in the Pacific. The insets show sea level changes in the Pacific Ocean caused by the recent El Nino and La Nina. Image credit: S. Nerem, University of Colorado. For a larger version of this image please go here.

Like mercury in a thermometer, ocean waters expand as they warm. This, along with melting glaciers and ice sheets in Greenland and Antarctica, drives sea levels higher over the long term. For the past 18 years, the U.S./French Jason-1, Jason-2 and Topex/Poseidon spacecraft have been monitoring the gradual rise of the world's ocean in response to global warming.

While the rise of the global ocean has been remarkably steady for most of this time, every once in a while, sea level rise hits a speed bump. This past year, it's been more like a pothole: between last summer and this one, global sea level actually fell by about a quarter of an inch, or half a centimeter.

So what's up with the down seas, and what does it mean? Climate scientist Josh Willis of NASA's Jet Propulsion Laboratory, Pasadena, Calif., says you can blame it on the cycle of El Nino and La Nina in the Pacific.

Willis said that while 2010 began with a sizable El Nino, by year's end, it was replaced by one of the strongest La Ninas in recent memory. This sudden shift in the Pacific changed rainfall patterns all across the globe, bringing massive floods to places like Australia and the Amazon basin, and drought to the southern United States.

Data from the NASA/German Aerospace Center's twin Gravity Recovery and Climate Experiment (Grace) spacecraft provide a clear picture of how this extra rain piled onto the continents in the early parts of 2011. "By detecting where water is on the continents, Grace shows us how water moves around the planet," says Steve Nerem, a sea level scientist at the University of Colorado in Boulder.

So where does all that extra water in Brazil and Australia come from? You guessed it--the ocean. Each year, huge amounts of water are evaporated from the ocean. While most of it falls right back into the ocean as rain, some of it falls over land.

"This year, the continents got an extra dose of rain, so much so that global sea levels actually fell over most of the last year," says Carmen Boening, a JPL oceanographer and climate scientist. Boening and colleagues presented these results recently at the annual Grace Science Team Meeting in Austin, Texas.

But for those who might argue that these data show us entering a long-term period of decline in global sea level, Willis cautions that sea level drops such as this one cannot last, and over the long-run, the trend remains solidly up. Water flows downhill, and the extra rain will eventually find its way back to the sea. When it does, global sea level will rise again.

"We're heating up the planet, and in the end that means more sea level rise," says Willis. "But El Nino and La Nina always take us on a rainfall rollercoaster, and in years like this they give us sea-level whiplash."

.


Related Links
NASA sea level monitoring satellites
Earth Observation News - Suppiliers, Technology and Application






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle








EARTH OBSERVATION
TRMM gets a look at Irene, the first hurricane of the Atlantic season
Greenebelt MD (SPX) Aug 24, 2011
The Tropical Rainfall Measuring Mission satellite has been busy measuring rainfall within Hurricane Irene, and forecasts call for between 5 and 10 inches in the southeastern and central Bahamas and Turks and Caicos Islands as Irene moves toward them. It's been a busy season so far in terms of tropical storms with seven named storms already in the Atlantic basin; however, none of them have ... read more


EARTH OBSERVATION
Man in the Moon Looking Younger

GRAIL Moon Twins are Joined to Their Booster

Moon younger than previously thought

GRAIL Launch Less Than One Month Away

EARTH OBSERVATION
Russian, European space agencies to team up for Mars mission

New Rover Snapshots Capture Endeavour Crater Vistas

France, Russia talk of Mars mission

Possibility of Mars microbial life eyed

EARTH OBSERVATION
Recent grad's astro feats regarded as research crown 'joule'

Draper Spacesuit Could Keep NASA Astronauts Stable, Healthier in Space

NASA Picks Three Proposals for Flight Demonstration

NASA Selects XCOR to Participate in Suborbital Flight Contract

EARTH OBSERVATION
Chinese orbiter launch failure will not affect unmanned space module launch

Rocket malfunction causes satellite to not reach preset orbit

China satellite aborts mission after 'malfunction'

Pausing for Tiangong

EARTH OBSERVATION
ISS crew safe despite supply failure: Russia, US

Robonaut successfully passes first test on ISS

Russian Progress space freighter set to undock from ISS

First 3D video transmission live from space

EARTH OBSERVATION
Russian spaceship crashes back to Earth

Russia grounds rockets after launch failure

Russia loses contact with new satellite

China successfully launches maritime satellite

EARTH OBSERVATION
Astronomers Find Ice and Possibly Methane on Snow White

Hubble to Target 'Hot Jupiters'

Stellar eclipse gives glimpse of exoplanet

Alien World is Blacker than Coal

EARTH OBSERVATION
Dutch judge slaps ban on Samsung smartphones

NRL Set to Launch Experimental TacSat-4 Spacecraft

New theory may shed light on dynamics of large-polymer liquids

Sony remodels PlayStation Home




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement