Featured Research

from universities, journals, and other organizations

TOPEX/Poseidon Satellite Finds Global Sea Level Change During El Nino

Date:
December 8, 1998
Source:
National Aeronautics And Space Administration
Summary:
The 1997-98 El Nino event may have been a major contributor in the average global sea level rising about eight-tenths of an inch before it returned to normal levels, according to scientists studying TOPEX/Poseidon satellite measurements of sea surface height.

The 1997-98 El Nino event may have been a major contributor in the average global sea level rising about eight-tenths of an inch before it returned to normal levels, according to scientists studying TOPEX/Poseidon satellite measurements of sea surface height.

"This is the first time we have been able to identify that El Nino may cause a change in average global sea level," said Dr. R. Steven Nerem, a TOPEX/Poseidon science team member at the Center for Space Research at the University of Texas at Austin. "Understanding these short-term variations is important for understanding and detecting long-term variations caused by climate change."

"TOPEX/Poseidon measures average global sea level at ten-day intervals with a precision of 0.16 inches, so detecting the 0.8-inch change associated with the El Nino was relatively easy," Nerem said. "However, these results tell us that detecting sea level variations caused by climate change will be more difficult because such changes are significantly smaller than the variations we have observed during the El Nino."

Key to understanding the changes in the ocean are the global maps made by TOPEX/Poseidon. The sea level rise was not confined to the tropical Pacific, but also was observed in the Indian Ocean and the southern Pacific. Nerem's team then calculated the average global sea level.

"These six years of satellite data are a good start, but we really need a decade or more of continuous measurements before we can accurately detect any climate-induced change," said Dr. Lee-Lueng Fu, the TOPEX/Poseidon project scientist at NASA's Jet Propulsion Laboratory (JPL), Pasadena, CA. "We need sustained observation records to understand the variations in the ocean."

Global mean sea level change on seasonal and inter-annual time scales is a measure of the changing heat content of the ocean. The 0.8-inch rise during the El Nino implies that on average the global ocean may be gaining heat.

"Average global sea level began rising in late March 1997, peaked at 0.8 inches above normal in early November 1997, and then began falling back to normal by the end of July 1998. Sea surface temperature began rising in late October 1996, peaked at 0.7 degrees Fahrenheit in late December 1997, and fell back to 0.2 degrees Fahrenheit at present," according to Nerem.

Developed by NASA and the French Centre National d'Etudes Spatiales (CNES), the TOPEX/Poseidon satellite, launched in August 1992, uses an altimeter to bounce radar signals off the ocean's surface to get precise measurements of the distance between the satellite and the sea surface. These data are combined with measurements from other instruments that pinpoint the satellite's exact location in space. Every ten days, scientists produce a complete map of global ocean topography, the barely perceptible hills and valleys found on the sea surface. A follow-on mission to TOPEX/Poseidon, Jason-1, is scheduled for launch in 2000.

An archive of TOPEX/Poseidon El Nino/La Nina images is available at:

http://www.jpl.nasa.gov/elnino

JPL manages the TOPEX/Poseidon mission for NASA's Earth Science Enterprise, Washington, DC. The Earth Science enterprise will combine measurements like those from TOPEX/Poseidon with other information about the land, sea, air, and life on Earth to develop a greater understanding and predictive capability of the global environmental system.


Story Source:

The above story is based on materials provided by National Aeronautics And Space Administration. Note: Materials may be edited for content and length.


Cite This Page:

National Aeronautics And Space Administration. "TOPEX/Poseidon Satellite Finds Global Sea Level Change During El Nino." ScienceDaily. ScienceDaily, 8 December 1998. <www.sciencedaily.com/releases/1998/12/981208053914.htm>.
National Aeronautics And Space Administration. (1998, December 8). TOPEX/Poseidon Satellite Finds Global Sea Level Change During El Nino. ScienceDaily. Retrieved September 19, 2014 from www.sciencedaily.com/releases/1998/12/981208053914.htm
National Aeronautics And Space Administration. "TOPEX/Poseidon Satellite Finds Global Sea Level Change During El Nino." ScienceDaily. www.sciencedaily.com/releases/1998/12/981208053914.htm (accessed September 19, 2014).

Share This



More Earth & Climate News

Friday, September 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Wildfires in CA Burn Forest Asunder

Raw: Wildfires in CA Burn Forest Asunder

AP (Sep. 18, 2014) — An out-of-control Northern California wildfire has nearly 2,800 people from their homes as it continues to grow, authorities said Thursday. Authorities said a man has been arrested on suspicion of arson for starting the fire on Saturday. (Sept. 18) Video provided by AP
Powered by NewsLook.com
Raw: Elephant Undergoes Surgery in Tbilisi Zoo

Raw: Elephant Undergoes Surgery in Tbilisi Zoo

AP (Sep. 18, 2014) — Grand the elephant has successfully undergone surgery to remove a portion of infected tusk at Tbilisi Zoo in Georgia. British veterinary surgeons used an electric drill to extract the infected piece. (Sept. 18) Video provided by AP
Powered by NewsLook.com
Raw: Scientists Examine Colossal Squid

Raw: Scientists Examine Colossal Squid

AP (Sep. 16, 2014) — Squid experts in New Zealand thawed and examined an unusual catch on Tuesday: a colossal squid. It was captured in Antarctica's remote Ross Sea in December last year and has been frozen for eight months. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Man Floats for 31 Hours in Gulf Waters

Man Floats for 31 Hours in Gulf Waters

AP (Sep. 16, 2014) — A Texas man is lucky to be alive after he and three others floated for more than a day in the Gulf of Mexico when their boat sank during a fishing trip. (Sept. 16) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins