研究长白山气候舒适期的变化,可以为其旅游业发展规划提供科学依据。基于1961—2018年长白山二道气象站逐日观测资料和NCEP/NCAR(National Centers for Environmental Prediction/Na⁃tional Center for Atmospheric Research)再分析资料...研究长白山气候舒适期的变化,可以为其旅游业发展规划提供科学依据。基于1961—2018年长白山二道气象站逐日观测资料和NCEP/NCAR(National Centers for Environmental Prediction/Na⁃tional Center for Atmospheric Research)再分析资料,分析长白山地区气候舒适期特征及其与大气环流的关系,并利用综合舒适指数对长白山气候舒适度进行评价。结果表明:长白山地区5—9月为气候舒适期,4月和10月为气候较舒适期。稳定气候舒适初日整体呈提前趋势[1.9 d·(10 a)^(-1)];稳定气候舒适终日整体呈推迟趋势[2.3 d·(10 a)^(-1)],且在1988年前后发生突变,由偏早转为偏晚。稳定气候舒适期平均为177 d,整体呈增长趋势[4.2 d·(10 a)^(-1)],其中1960—1980年代初期为偏短期,1980—1990年代中期为平稳期,1990年代中期以后转变为偏长期,并存在3~5 a周期。当东亚地区春季500 hPa高度场正异常,有利于稳定气候舒适初日异常偏早,反之异常偏晚;当东亚—西北太平洋地区500 hPa高度场存在负异常,有利于稳定气候舒适终日异常偏早,反之异常偏晚。展开更多
The present study explored how the Indian Ocean Dipole (IOD) influences October-November-December (OND) rainfall over Tanzania in recent decade following the 2011 abrupt change. The study spans 50 years, from 1973 to ...The present study explored how the Indian Ocean Dipole (IOD) influences October-November-December (OND) rainfall over Tanzania in recent decade following the 2011 abrupt change. The study spans 50 years, from 1973 to 2022. Notable abrupt changes were observed in 1976 and 2011, leading us to divide our study into two periods: 1976-2010 and 2011-2022, allowing for a close investigation into the existing relationship between OND IOD and OND rainfall and their associated large-scale atmospheric circulations. It was found that the relationship between OND IOD and OND rainfall strengthened, with the correlation changed from +0.73 during 1976-2010 to +0.81 during 2011-2022. Further investigation revealed that, during 1976-2010, areas that received above- normal rainfall during positive IOD experienced below-normal during 2011- 2022 and vice versa. The same pattern relationship was observed for negative IOD. Spatial analysis demonstrates that the percentage departure of rainfall across the region mirrors the standardized rainfall anomalies. The study highlights that the changing relationship between OND IOD and OND rainfall corresponds to the east-west shift of Walker circulation, as well as the north-south shift of Hadley circulation. Analysis of sea surface temperature (SST) indicates that both positive and negative IOD events strengthened during 2011-2022 compared to 1976-2010. Close monitoring of this relationship across different timescales could be useful for updating OND rainfall seasonal forecasts in Tanzania, serving as a tool for reducing socio-economic impacts.展开更多
文摘The present study explored how the Indian Ocean Dipole (IOD) influences October-November-December (OND) rainfall over Tanzania in recent decade following the 2011 abrupt change. The study spans 50 years, from 1973 to 2022. Notable abrupt changes were observed in 1976 and 2011, leading us to divide our study into two periods: 1976-2010 and 2011-2022, allowing for a close investigation into the existing relationship between OND IOD and OND rainfall and their associated large-scale atmospheric circulations. It was found that the relationship between OND IOD and OND rainfall strengthened, with the correlation changed from +0.73 during 1976-2010 to +0.81 during 2011-2022. Further investigation revealed that, during 1976-2010, areas that received above- normal rainfall during positive IOD experienced below-normal during 2011- 2022 and vice versa. The same pattern relationship was observed for negative IOD. Spatial analysis demonstrates that the percentage departure of rainfall across the region mirrors the standardized rainfall anomalies. The study highlights that the changing relationship between OND IOD and OND rainfall corresponds to the east-west shift of Walker circulation, as well as the north-south shift of Hadley circulation. Analysis of sea surface temperature (SST) indicates that both positive and negative IOD events strengthened during 2011-2022 compared to 1976-2010. Close monitoring of this relationship across different timescales could be useful for updating OND rainfall seasonal forecasts in Tanzania, serving as a tool for reducing socio-economic impacts.
