IFPRI                 Delayed Impact of the North               Atlantic Oscillation on Biosphere                     Prod...
OutlineNAOMotivationData and Method Panel Data of Chinese Crop yields NDVIResultsConclusions
North Atlantic Oscillation (NAO) NAO: an oscillation in the gradient of atmospheric pressure between the high pressure cen...
Motivation Impact on flora and fauna patterns Although the NAO-related temperature pattern extends far eastward into north...
Our Study We investigate the impact of NAO on the productivity of vegetation in Asia at various time lags We found that th...
Our Data Chinese provincial crop yield data from 1979-1997: rice, wheat, maize, sorghum, millet, potato, and soybean Satel...
Our Data (Continued) PC-based NAO index during the extended winter (December through March), provided by NCAR
Our Method - Correlation Analysis A relationship as being significant only if all of the following four conditions are met...
Correlation coefficients between winterNAO index and crop yields
Correlation between winter NAO indexand monthly NDVI in subsequent spring
Correlation between winter NAO indexand NDVI in the 2nd growing season
Correlation between the NAO index andNDVI
Three Characteristics The time lag between the NAO index and NDVI is approximately the same as that between the NAO index ...
Findings The crop yield data from China and the satellite NDVI data are consistent A significant response of vegetation pr...
Discussion The significant response of vegetation productivity in Asia to NAO with a delay as long as 1.5 years indicates ...
Implications Studies linking carbon dynamics to modes of atmospheric circulation should take into account this delayed res...
The first paper already published inGeophysical Research Letter
New Research North Atlantic Oscillation as a long- range forecast of crop yield in North Asia, in particular North Korea N...
Thank You All!
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You Liangzhi — Delayed impact of the north atlantic oscillation on biosphere productivity in asia

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The Chinese Academy of Agricultural Sciences (CAAS) and the International Food Policy Research Institute (IFPRI) jointly hosted the International Conference on Climate Change and Food Security (ICCCFS) November 6-8, 2011 in Beijing, China. This conference provided a forum for leading international scientists and young researchers to present their latest research findings, exchange their research ideas, and share their experiences in the field of climate change and food security. The event included technical sessions, poster sessions, and social events. The conference results and recommendations were presented at the global climate talks in Durban, South Africa during an official side event on December 1.

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You Liangzhi — Delayed impact of the north atlantic oscillation on biosphere productivity in asia

  1. 1. IFPRI Delayed Impact of the North Atlantic Oscillation on Biosphere Productivity in Asia Guiling Wang Liangzhi You International Conference on Climate Change and Food Security Beijing, November 07, 2011INTERNATIONAL FOOD POLICY RESEARCH INSTITUTE
  2. 2. OutlineNAOMotivationData and Method Panel Data of Chinese Crop yields NDVIResultsConclusions
  3. 3. North Atlantic Oscillation (NAO) NAO: an oscillation in the gradient of atmospheric pressure between the high pressure center near the Azores and the low pressure center near Iceland on the Atlantic . Through its impact on atmospheric circulation, NAO regulates climate variability in most of the Northern Hemisphere. Positive vs. negative phases of NAO
  4. 4. Motivation Impact on flora and fauna patterns Although the NAO-related temperature pattern extends far eastward into northern Asia, few documented studies so far Based on the current notion of the NAO phenomenon, a time lag longer than a few months in vegetation response is neither expected nor easily explained
  5. 5. Our Study We investigate the impact of NAO on the productivity of vegetation in Asia at various time lags We found that the vegetation response time in Asia is even longer, at a surprising 18 months
  6. 6. Our Data Chinese provincial crop yield data from 1979-1997: rice, wheat, maize, sorghum, millet, potato, and soybean Satellite-derived monthly Normalized Difference Vegetation Index (NDVI)- ”Greenness Index” The monthly NDVI data was derived from the Advanced Very High Resolution Radiometer. It spans the period 1982-2000, and covers the globe with a 1-degree spatial resolution
  7. 7. Our Data (Continued) PC-based NAO index during the extended winter (December through March), provided by NCAR
  8. 8. Our Method - Correlation Analysis A relationship as being significant only if all of the following four conditions are met: » the correlation based on raw data is significant » the correlation based on detrended data is significant » detrending the data does not change the sign of the correlation coefficient » the above three criteria are met in at least one contingent area that is larger than the size of three medium provinces in China
  9. 9. Correlation coefficients between winterNAO index and crop yields
  10. 10. Correlation between winter NAO indexand monthly NDVI in subsequent spring
  11. 11. Correlation between winter NAO indexand NDVI in the 2nd growing season
  12. 12. Correlation between the NAO index andNDVI
  13. 13. Three Characteristics The time lag between the NAO index and NDVI is approximately the same as that between the NAO index and crop yield The time of significant NAO association identified from the NDVI data (i.e., July- October) covers most of the growing season of the crops for which our crop data establishes a delayed response to NAO The region of significant NAO-NDVI correlation in Asia covers the northern China where crop yield data suggests a delayed response of vegetation productivity to NAO
  14. 14. Findings The crop yield data from China and the satellite NDVI data are consistent A significant response of vegetation productivity in Asia to the NAO system with a time delay of one and half years
  15. 15. Discussion The significant response of vegetation productivity in Asia to NAO with a delay as long as 1.5 years indicates that the lasting memory may reside in some large scale forcing The role of the Arctic Ocean?
  16. 16. Implications Studies linking carbon dynamics to modes of atmospheric circulation should take into account this delayed response in biosphere carbon assimilation The timing difference between Europe and Asia in their ecological responses to NAO demands separate treatment of these two continents in many studies NAO index as a weather-related predictor for long-range forecast of several grain crop yields in North Asia
  17. 17. The first paper already published inGeophysical Research Letter
  18. 18. New Research North Atlantic Oscillation as a long- range forecast of crop yield in North Asia, in particular North Korea NSF-funded project(2011-2014): A Pilot Project on Interactive Climate and Land Use Predictions
  19. 19. Thank You All!

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