Classical monsoon dynamics considers the winter/spring snow amount on the Tibetan Plateau(TP)as a major factor driving the East Asian summer monsoon(EASM)for its direct influence on the land-sea thermal contrast.Actua...Classical monsoon dynamics considers the winter/spring snow amount on the Tibetan Plateau(TP)as a major factor driving the East Asian summer monsoon(EASM)for its direct influence on the land-sea thermal contrast.Actually,the TP snow increased and decreased after the late 1970s and 1990s,respectively,accompanying the two major interdecadal changes in the EASM.Although studies have explored the possible mechanisms of the EASM interdecadal variations,and change in TP snow is considered as one of the major drivers,few studies have illustrated the underlying mechanisms of the interdecadal changes in the winter TP snow.This study reveals a tripole pattern of change,with decreased winter precipitation over the TP and an increase to its north and south after the late 1990s.Further analyses through numerical experiments demonstrate that the tropical Pacific SST changes in the late 1990s can robustly affect the winter TP precipitation through regulating the Walker and regional Hadley circulation.The cooling over the tropical central-eastern Pacific can enhance the Walker circulation cell over the Pacific and induce ascending motion anomalies over the Indo-Pacific region.These anomalies further drive descending motion anomalies over the TP and ascending motion anomalies to the north through regulating the regional Hadley circulation.Therefore,the positive-negative-positive winter precipitation anomalies around the TP are formed.This study improves the previously poor understanding of TP climate variation at interdecadal timescales.展开更多
The spatial and temporal distribution patterns of the zooplankton of Chabahar Bay, Gulf of Oman were investigated. Zooplankton sampling was collected twice a season at five stations in Chabahar Bay. Sampling was done ...The spatial and temporal distribution patterns of the zooplankton of Chabahar Bay, Gulf of Oman were investigated. Zooplankton sampling was collected twice a season at five stations in Chabahar Bay. Sampling was done during July-August 2007 （SW-monsoon）, October-November 2007 （post-monsoon）, January-February 2008 （NE-monsoon）, and March-May 2008 （pre-monsoon）. Five stations were investigated throughout Chabahar Bay. Four species of Oncaeidae （Oncaea media, Oncaea minuta, Oncaea venusta and Oncaea clevei） were identified. The abundance of Oncaea media was maximum in the post-monsoon （〉 700 ind..m3） and disappeared in pre-monsoon while Oncaea minuta was maximum in post-monsoon （〉 130 ind..m3） and disappeared in NE-monsoon and pre-monsoon. Oncaea venusta showed the highest abundance in post-monsoon （〉 370 ind..m3） and the lowest in pre-monsoon （〈 55 ind..m-3）. The highest abundance of Oncaea clevei was in post-monsoon （〈 240 ind..m-3） and lowest in NE-monsoon. Overall, the highest abundance of Oncaeidae was observed in post-monsoon. The results showed that depth was the most important factor controlling abundance of the Oncaeidae. Spatially, the highest abundance of Oncaeidae species was found in off shore stations. Four species of this family showed positive correlation with depth. Also, O. venusta showed negative correlation with salinity that showed this species prefers low saline water.展开更多
基金This study was jointly supported by the Second Tibetan Plateau Scientific Expedition and Research(STEP)program[grant number 2019QZKK0102]the National Natural Science Foundation of China[grant numbers 41675083 and 41991281].
文摘Classical monsoon dynamics considers the winter/spring snow amount on the Tibetan Plateau(TP)as a major factor driving the East Asian summer monsoon(EASM)for its direct influence on the land-sea thermal contrast.Actually,the TP snow increased and decreased after the late 1970s and 1990s,respectively,accompanying the two major interdecadal changes in the EASM.Although studies have explored the possible mechanisms of the EASM interdecadal variations,and change in TP snow is considered as one of the major drivers,few studies have illustrated the underlying mechanisms of the interdecadal changes in the winter TP snow.This study reveals a tripole pattern of change,with decreased winter precipitation over the TP and an increase to its north and south after the late 1990s.Further analyses through numerical experiments demonstrate that the tropical Pacific SST changes in the late 1990s can robustly affect the winter TP precipitation through regulating the Walker and regional Hadley circulation.The cooling over the tropical central-eastern Pacific can enhance the Walker circulation cell over the Pacific and induce ascending motion anomalies over the Indo-Pacific region.These anomalies further drive descending motion anomalies over the TP and ascending motion anomalies to the north through regulating the regional Hadley circulation.Therefore,the positive-negative-positive winter precipitation anomalies around the TP are formed.This study improves the previously poor understanding of TP climate variation at interdecadal timescales.
文摘The spatial and temporal distribution patterns of the zooplankton of Chabahar Bay, Gulf of Oman were investigated. Zooplankton sampling was collected twice a season at five stations in Chabahar Bay. Sampling was done during July-August 2007 （SW-monsoon）, October-November 2007 （post-monsoon）, January-February 2008 （NE-monsoon）, and March-May 2008 （pre-monsoon）. Five stations were investigated throughout Chabahar Bay. Four species of Oncaeidae （Oncaea media, Oncaea minuta, Oncaea venusta and Oncaea clevei） were identified. The abundance of Oncaea media was maximum in the post-monsoon （〉 700 ind..m3） and disappeared in pre-monsoon while Oncaea minuta was maximum in post-monsoon （〉 130 ind..m3） and disappeared in NE-monsoon and pre-monsoon. Oncaea venusta showed the highest abundance in post-monsoon （〉 370 ind..m3） and the lowest in pre-monsoon （〈 55 ind..m-3）. The highest abundance of Oncaea clevei was in post-monsoon （〈 240 ind..m-3） and lowest in NE-monsoon. Overall, the highest abundance of Oncaeidae was observed in post-monsoon. The results showed that depth was the most important factor controlling abundance of the Oncaeidae. Spatially, the highest abundance of Oncaeidae species was found in off shore stations. Four species of this family showed positive correlation with depth. Also, O. venusta showed negative correlation with salinity that showed this species prefers low saline water.
