Changes in the Gulf Stream Correlates with Changes in Climate
13 Mar, 2008 01:01 am
A paper in this week's Nature studies the Gulf Stream in depth and the potential of this ocean current on influencing the climate. Scitizen interviews the study author, Shoshiro Minobe.
1. What interested you and your colleagues in this study, and what is the method of your study?
We employ combination of data analysis of high-resolution operational weather analysis and satellite observations, and high-resolution numerical experiments using an atmospheric
general circulation model on the Earth Simulator.
2. Your study focused on what is occuring in the troposphere (the lowest part of the atmosphere). What did you discover here?
We discovered that the heat transported by the Gulf Stream and released to the atmosphere cause substantial and systematic impacts in the entire troposphere. The troposphere, which occupies about 80% of the mass of the atmosphere, is the stage where important weather phenomena, such as clouds and precipitation occur.
3. How do the results of your study contribute to what we know of climatic response to changes in ocean circulation?
Our study suggests that, for example, if the Gulf Stream migrate meridionally, the whole atmospheric responses including the precipitation band also migrate as well. Also, if the Gulf Stream is weakened or strengthened, the amplitudes of the atmospheric responses will change accordingly.
4. What do you estimate might be the long-term effects?
This is really interesting question. Our results suggest that if we can estimate the long-term changes of the Gulf Stream, we can also estimate changes of local climate. For the future changes of the Gulf Stream, however, I think that we only have a crude knowledge. The climate models used for the IPCC AR4 does not have enough resolution to express the Gulf Stream properly. Our findings suggest that in order to know the local and probably remote climate changes it is important to properly express the Gulf Stream and other strong ocean currents in climate models.
This 3-dimensional view of surface current speeds in blue-white colors (white for faster current speeds) and upward wind velocities in yellow-red colors (red for stronger upward winds) along with land-surface topography in eastern North America, clearly indicating that the Gulf Stream anchors a tall wall of atmospheric upward motion that penetrates into the upper troposphere and supports deep raining clouds. The images are produced by F. Araki and S. Kawahara, ESC JAMSTEC. Reference:
Shoshiro Minobe et al. Nature 452, no. 7184, 13 MARCH 2008.
Interview by Audrey Wang
2 comment(s)
[1]
Comment by David B. Benson
13 Mar, 2008 06:57 pm
Impressive graphic, quite helpful.
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[2]
Comment by A.Bernaerts
15 Mar, 2008 08:19 pm
Would Dr Shoshiro Minobe et al. be able and willing to extend the investigation to the part of the Gulf Stream that passes the Norwegian archipelagos Spitsbergen at ca 78 degrees North and which is most likely responsible for the early Arctic warming starting in the late 1910s and lasting for two decades? As the northern North Atlantic is ice covered from Iceland to Bear Island, except a narrow tongue along Spitsbergen up to the Arctic Ocean during the late winter season (see graph at : http://www.arctic-warming.com/), the arctic warming 90 years ago, can only have been generated by the northern arm of the Gulf Stream that passes Spitsbergen in the West, and keep a small section of the sea ice free up to latitude 80 degrees North. After all the sudden commencement of the extreme warming at Spitsbergen and the wider Arctic region around winter 1918/19 was puzzling to scholars in the 1930s and even today some regard the event as ?one of the most puzzling climate anomalies of the 20 the century? (Lennart Bengtsson, JoC 2004, p. 4045-4057). The authors of NATURE article: ?Influence of the Gulf Stream on the troposphere?, should use the early Arctic warming to enhance their thesis. After all, the northern North Atlantic is ice covered from Iceland to Bear Island, except a narrow tongue along Spitsbergen up to the Arctic Ocean during the late winter season (see graph at reference website), the arctic warming 90 years ago can have been generated only by the northern arm of the Gulf Stream that passes Spitsbergen in the West, and keep a small section of the sea ice free up to latitude 80 degrees North.
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