Developing a new method to remove the bias, Hiroki Tokinaga and Shang-Ping Xie at the International Pacific Research Center, University of Hawaii at Manoa, found that their corrected observations show the trade winds in the tropical Atlantic have weakened and the pattern of ocean surface temperature has changed. As a result, the equatorial Amazon and the Guinea Coast are seeing more rainfall and the Sahel less. The findings are published online in the February 6, 2011, issue of Nature Geoscience.
The raw observations of winds over the ocean suggest that the winds have grown stronger during the last 60 years. The trend is, however, largely due to a change in the placement of the anemometers, the instruments measuring wind speed. Ships are the main source of wind data over the ocean, and ships have increased in height and so has the anemometer placement. Tokinaga and Xie corrected this wind bias using wind-wave heights. The tropical Atlantic has three major ship routes along which ships provide meteorological data. Applying their new correction technique to observations along these routes from 1950 to 2009 together with other observations, they found the trade winds in the tropical Atlantic had weakened significantly during this period.Although ocean surface temperature in the tropical Atlantic has risen, the pattern has changed and with it the climate. The cold tongue of water that stretches out from the eastern tropical Atlantic coast has warmed more than the western part of the basin. At the same time, the weakened trade winds have resulted in less upwelling of cold water and nutrients in the eastern tropical Atlantic. These latter changes could impact marine life.
Tokinaga and Xie reason that the pattern of ocean warming and trade-wind changes are caused by the asymmetric reduction in surface solar radiation due to man-produced aerosols, the reduction affecting the Northern more than the Southern Hemisphere. If aerosol emissions decrease over the next decades, the tropical Atlantic climate may experience yet another shift as greenhouse gas forcing increases. Such a shift in the patterns of climate change (i.e., precipitation and sea level) will have important impacts on the socio-economics of regions surrounding the tropical Atlantic. For example, "If the year-to-year variability is to recover in the future, the resulting increase in climate extremes would add burdens to an ecosystem and to a society already stressed by global warming," said Tokinaga.
Historical observations of accurate winds are gravely lacking over the World's oceans. This new robust and physically consistent set of observations by the IPRC team is valuable for improving computer models and evaluating model projections of climate change under further global warming.
This research was supported by NOAA, the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), NASA, and NSF, which sponsor research at the International Pacific Research Center.
Citation: Tokinaga, H., and S.-P. Xie, 2011: Weakening of the equatorial Atlantic cold tongue over the past six decades. Nature Geoscience, http://dx.doi.org/10.1038/NGEO1078.Researcher Contacts:
The International Pacific Research Center (IPRC) of the School of Ocean and Earth Science and Technology (SOEST) at the University of Hawai`i at Mânoa, is a climate research center founded to gain greater understanding of the climate system and the nature and causes of climate variation in the Asia-Pacific region and how global climate changes may affect the region. Established under the "U.S.-Japan Common Agenda for Cooperation in Global Perspective" in October 1997, the IPRC is a collaborative effort between agencies in Japan and the United States.
Gisela Speidel | EurekAlert!
NASA examines Peru's deadly rainfall
24.03.2017 | NASA/Goddard Space Flight Center
Steep rise of the Bernese Alps
24.03.2017 | Universität Bern
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
24.03.2017 | Materials Sciences
24.03.2017 | Physics and Astronomy
24.03.2017 | Physics and Astronomy