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The tenth IMSC, Beijing, China, 2007 - International Meetings on ...

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model has been applied to the series of the Siberian high index and dem<strong>on</strong>strated its ability for<br />

fitting and forecasting.Besides, the relati<strong>on</strong>ship between the Siberian high in winter and the<br />

East-Asian summer m<strong>on</strong>so<strong>on</strong> was studied. <str<strong>on</strong>g>The</str<strong>on</strong>g> synchr<strong>on</strong>izati<strong>on</strong> between the Siberian high in<br />

winter and the East-Asian summer m<strong>on</strong>so<strong>on</strong> existed before 1925, after that the variati<strong>on</strong>s of<br />

both the Siberian high in winter and the East-Asian summer m<strong>on</strong>so<strong>on</strong> were quite different, the<br />

East-Asian summer m<strong>on</strong>so<strong>on</strong> became weaker.<br />

L<strong>on</strong>g-term Probabilistic Forecast and T* Distributi<strong>on</strong><br />

Shao-Hang Chu<br />

US Envir<strong>on</strong>mental Protecti<strong>on</strong> Agency<br />

chu.shao-hang@epa.gov<br />

Models are great tools to test ideas. <str<strong>on</strong>g>The</str<strong>on</strong>g>ir usefulness, however, depends <strong>on</strong> their ability to<br />

simulate the current reality and predict the future. In this study, I show that a statistical model<br />

based <strong>on</strong> a new t*-distributi<strong>on</strong> of stati<strong>on</strong> temporal data is capable of predicting the probability<br />

of any future outcome to exceed a specific value using <strong>on</strong>ly the currently available sample<br />

statistics assuming a normal random variable. In an air quality management applicati<strong>on</strong>, the<br />

model has dem<strong>on</strong>strated categorically an average success rate of over 80% both in simulating<br />

the current oz<strong>on</strong>e n<strong>on</strong>-attainment areas and forecasting the rate of future violati<strong>on</strong> of the<br />

8-hour oz<strong>on</strong>e Nati<strong>on</strong>al Ambient Air Quality Standards in the U.S. for up to 12 years. While the<br />

predictability of deterministic climate models is still limited by large uncertainties, the<br />

probabilistic forecast by this model provides a promising alternative in assessing the climate<br />

impact <strong>on</strong> envir<strong>on</strong>ment for decades.<br />

Spatial Drought Rec<strong>on</strong>structi<strong>on</strong> Based On Point-By-Point Regressi<strong>on</strong><br />

Edward R. Cook<br />

Tree-Ring Laboratory, Lam<strong>on</strong>t-Doherty Earth Observatory, 61 Route 9W, Palisades, NY 10964<br />

drdendro@ldeo.columbia.edu<br />

<str<strong>on</strong>g>The</str<strong>on</strong>g> paleoclimate rec<strong>on</strong>structi<strong>on</strong> of climate fields is often c<strong>on</strong>sidered a joint space-time<br />

estimati<strong>on</strong> problem where the predictand climate field, typically <strong>on</strong> a regular grid, is<br />

rec<strong>on</strong>structed simultaneously from an irregular predictor network of paleoclimate proxies. In<br />

dendroclimatology, there is a rich history of doing this as far back as 1971. In so doing, sea<br />

level pressure, temperature, precipitati<strong>on</strong>, and drought fields have been successfully<br />

rec<strong>on</strong>structed from tree-ring networks using a variety of reduced space multivariate regressi<strong>on</strong><br />

methods. While such methods can work well, they are also difficult to diagnose because the<br />

network of predictors is c<strong>on</strong>tributing jointly to the rec<strong>on</strong>structi<strong>on</strong> of the climate field in a<br />

potentially very complicated way. Thus, why a reduced space multivariate method might fail to<br />

skillfully rec<strong>on</strong>struct certain areas of a climate field might be impossible to identify and correct<br />

109

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