Featured Research

from universities, journals, and other organizations

Gulf Stream Leaves Its Signature Seven Miles High

Date:
March 24, 2008
Source:
University of Hawaii at Manoa
Summary:
The Gulf Stream's impact on climate is well known, keeping Iceland and Scotland comfortable in winter compared to the deep-freeze of Labrador at the same latitude. That cyclones tend to spawn over the Gulf Stream has also been known for some time. A new study reveals that the Gulf Stream anchors a precipitation band with upward motions and cloud formations that can reach 7 miles high and penetrate the upper troposphere. The discovery shows that the Gulf Stream has a pathway by which to directly affect weather and climate patterns over the whole Northern Hemisphere, and perhaps even world wide.

Cumulonimbus storm cloud forming over the warm Gulf Stream along the Norwegian coast. The system is sometimes called a polar low.
Credit: iStockphoto/Erik Kolstad

The Gulf Stream’s impact on climate is well known, keeping Iceland and Scotland comfortable in winter compared to the deep-freeze of Labrador at the same latitude. That cyclones tend to spawn over the Gulf Stream has also been known for some time. A new study reveals that the Gulf Stream anchors a precipitation band with upward motions and cloud formations that can reach 7 miles high and penetrate the upper troposphere. The discovery, announced by a Japan–US team of scientists, shows that the Gulf Stream has a pathway by which to directly affect weather and climate patterns over the whole Northern Hemisphere, and perhaps even world wide.

“Our findings gain even more significance by the fact that the Gulf Stream is the upper limb of the Atlantic portion of the ocean conveyor belt that drives the global ocean circulation,” says co-author Shang-Ping Xie, a research team leader at the International Pacific Research Center in the School of Ocean and Earth Science and Technology, and professor of meteorology at the University of Hawai’i at Manoa. “The conveyor belt is predicted to slow down with global warming, which implies that changes in the Gulf Stream will modulate spatial patterns of future climate change.”

Xie has been curious for some time about the response of the atmosphere to warm currents flowing within cold ocean water, such as the Gulf Stream or its Pacific counterpart, the Kuroshio. Xie says, “It has been a challenging task to isolate the climatic influence of the Gulf Stream from energetic weather variations by using conventional observations, which are spatially and temporally sporadic. Our findings were only possible because of the availability of high-resolution satellite data, an operational weather analysis, and an atmospheric circulation model.”

The first hint that these warm ocean currents have a significant effect on the atmosphere came from high-resolution NASA satellite data. These images show a narrow rain band hovering frequently over the warm flank of the currents; wind accelerates and converges over the warm flank and diverges and decelerates on the cold flank.

The satellite images, however, do not allow accurate measurements of upward motions and divergence of air in the upper troposphere, which are necessary to understand the link between the current and large-scale climate. This is where the European Center for Medium-Range Weather Forecasts (ECMWF) analysis provided the missing data. “It is remarkable to see how the diverging winds 7 miles high show a structure similar to the converging winds and the rain clouds, all meandering with the Gulf Stream,” says lead author Shoshiro Minobe, a professor at the Division of Earth and Planetary Sciences at Hokkaido University.

The upward wind velocity is strongest about the first mile above the surface, but the Gulf Stream-following structure is clearly visible at 4 miles and still discernible at 7 miles and above. The band of diverging winds in the upper troposphere follows the meandering Gulf Stream front.

The findings from the operational weather analysis pointed to the warm flank of the Gulf Stream as the cause of the strong upward winds. “We wanted more evidence, though,” says team member Akira Kuwano-Yoshida of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), “and turned to the high-resolution Atmospheric Model for the Earth Simulator (AGCM) at JAMSTEC. We drove the model first with the actual Gulf Stream temperatures. The model successfully captured the rain band and the signature in the upper troposphere. Then we removed the sharp sea surface gradient from the Gulf Stream front by smoothing the temperature in the model. The narrow rain band disappeared.”

Finally, the team used outgoing longwave radiation satellite data to measure the cloud top temperatures. The narrow cloud band, associated with lightning, extends 7 miles high above the Gulf Stream meanders and has temperatures below freezing. All this is further evidence that the Gulf Stream influence on the atmosphere extends far above the lower atmosphere.

The Gulf Stream’s strength has changed markedly in the past as Earth has switched between warm periods and ice ages. Closely linked to these changes have been climate changes around the globe—not only in the Atlantic, but also in the Pacific and even in the Southern Hemisphere. Scientists have been puzzled at how the changes in the Atlantic thermohaline circulation (the conveyor belt) lead to climate anomalies in other regions in the Northern Hemisphere. The new study discovers a direct pathway, the Gulf Stream’s deep heating of the atmosphere. This heating generates planetary waves that can induce quite rapid changes in Earth’s atmospheric circulation and alter climate over Europe and beyond by riding on the westerly jet stream in the upper troposphere.

Journal reference: Minobe, S., A. Kuwano-Yoshida, N. Komori, S.-P. Xie, and R.J. Small, 2008: Influence of the Gulf Stream on the troposphere. Nature. March 13, 2008.


Story Source:

The above story is based on materials provided by University of Hawaii at Manoa. Note: Materials may be edited for content and length.


Cite This Page:

University of Hawaii at Manoa. "Gulf Stream Leaves Its Signature Seven Miles High." ScienceDaily. ScienceDaily, 24 March 2008. <www.sciencedaily.com/releases/2008/03/080320181838.htm>.
University of Hawaii at Manoa. (2008, March 24). Gulf Stream Leaves Its Signature Seven Miles High. ScienceDaily. Retrieved September 19, 2014 from www.sciencedaily.com/releases/2008/03/080320181838.htm
University of Hawaii at Manoa. "Gulf Stream Leaves Its Signature Seven Miles High." ScienceDaily. www.sciencedaily.com/releases/2008/03/080320181838.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