Potential Impacts of Winter Arctic Sea Ice on Subsequent Spring Thermal Condition Over the Tibetan Plateau

JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES(2024)

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摘要
Spring thermal forcing over the Tibetan Plateau (TP) is largely determined by surface sensible heating (SSH), which is an important fuel for atmospheric circulations over subtropics and even the globe. However, insufficient efforts were devoted on exploring the potential influencing factors of spring TP's SSH. In the current study, observational analysis and model results confirm that the sea ice concentration in the north of Greenland can act as a precursor. Specifically, the winter shrinkage of the sea ice concentration can stimulate a meridional Rossby wave train, with a remarkable positive-negative-positive pattern of geopotential height anomalies controlling the Arctic, western Eurasia, and the southeastern Mediterranean, respectively. This teleconnection is equivalent barotropic in the whole troposphere, which shifts southeastward from winter to spring, with a significant anomalous anticyclone and increased geopotential height dominating the western TP in spring. The surface northeasterly anomalies in the southeastern flank of the anticyclone decrease the climatological westerlies and weaken the SSH over the central-southern TP. Existing literature mainly focused on the Arctic-TP relationship in autumn and winter. Our finding can not only provide a new insight onto the variation of spring thermal condition over the TP, but also deepen our knowledge of cross-seasonal relationships between the Arctic and the TP with similar snow-ice albedo feedback. Surface sensible heating (SSH) over the Tibetan Plateau (TP) in spring can modulate subsequent Asian summer monsoon system and even the winter El Nino-Southern Oscillation events, and then exert profound impacts on the global ecosystems and human livelihoods. However, less attention has been paid on exploring its potential influencing factors. Relationships between the Arctic and the TP have gained increasing popularities in recent decades. However, plentiful studies concentrated on the Arctic-TP connections in autumn and winter. Investigations on whether the preceding Arctic sea ice can modulate spring TP's SSH remain inadequate. This study reveals a close linkage between winter sea ice concentration (SIC) in the north of Greenland and subsequent spring TP's SSH. Specifically, diminished (enhanced) winter SIC can generate a Rossby wave train extending along the Arctic, western Eurasia, and the western TP, resulting in decreased (increased) spring TP's SSH. This finding is expected to bridge the cross-seasonal gap of the Arctic-TP relationship. A cross-seasonal linkage exists between winter sea ice over the north of Greenland and spring thermal condition over the TP The linkage is established through a Rossby wave train extending along the Arctic, western Eurasia, and the western TP The anticyclonic anomalies induced by the Rossby wave train weaken surface wind speed and thermal condition over the central-southern TP in spring
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