HFP2季节预报中的长期线性趋势
- 作者：贾晓静Hai Lin
- 会议时间：2014-11-03
- 作者单位：贾晓静(浙江大学地球科学系,浙江杭州,310027)Hai Lin(加拿大环境部,加拿大Dorval市)
- 会议名称：第31届中国气象学会年会
- 会议地点：北京
- 主办单位：中国气象学会
- 语种：chi
- 分类号：P45;P4
摘要
The climate trend in a dynamical seasonal forecasting system is examined using 33-year multi-model ensemble (MME) forecasts from the second phase of the Canadian Historical Forecasting Project (HFP2).It is found that the warming trend of the seasonal forecast in MAM (March-May) over the Eurasian continent is in a good agreement with that in the observations.However,the seasonal forecast failed to reproduce the observed pronounced SAT trend in DJF(December-February).The possible reasons responsible for the different behaviors of the HFP2 models in MAM and DJF are investigated.Results show that the initial conditions used for the HFP2 forecast system in MAM has a warming trend over the Eurasian continent,which may come from high-frequency weather systems,whereas the initial conditions for the DJF seasonal forecast do not have such a trend.This trend in the initial condition contributes to the trend of the seasonal forecast in the first month.On the other hand,an examination of the lower boundary SST anomaly forcing shows that the SST trend in MAM has a negative SST anomaly along the central equatorial Pacific which is favorable for a positive phase of the North Atlantic Oscillation atmospheric response and a warming over the Eurasian continent.The long-term SST trend used for the seasonal forecast in DJF,however,has a negative trend in the tropical eastern Pacific which is associated with a Pacific-North American pattern-like atmospheric response that has little contribution to a warming in the Eurasian continent.