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Changes in winter cloudy days (CDs) exert substantial impacts on agricultural production, public transport, and the solar photovoltaic (PV) power industry. However, the physical mechanism behind the variability of winter CDs over China remains largely unclear, making it challenging to predict the future dynamics of winter CDs. In this study, we explored the spatiotemporal features of winter CDs over China from 1961 to 2013 and identified two independent formation mechanisms associated with its leading mode. Then, we projected the future changes (2021–2099) in winter CDs under global warming constrained by the identified formation mechanisms. Results revealed that: (a) The leading mode of winter CDs from 1961 to 2013 presents a homogeneous pattern. The positive winter CDs anomaly is connected to the anomalous southerlies related to the Eurasian Rossby wave train triggered by the Barents Sea thermal forcing, as well as the Asia‐Pacific zonal geopotential height gradient induced by the convection over the Maritime Continent; (b) Selected state‐of‐the‐art climate models project a notable decrease in winter CDs in the Tibetan Plateau and southern China regions, and almost unchanged winter CDs over northern China, under global warming; (c) In contrast to present‐day mechanisms, in the future, the shift of the Eurasian mean flow will terminate the role of the Barents Sea thermal forcing. Instead, the enhanced convection over the Maritime Continent emerges as the primary contributor to the decline in winter CDs. Our findings provide valuable insights for policymakers in the solar PV industry, particularly in relation to the challenges faced under global warming. Plain Language Summary: Winter cloudy days (CDs) over China exhibit significant spatiotemporal variability, greatly impacting agriculture, transportation, and the solar photovoltaic (PV) power industry. However, the physical mechanism and future changes of winter CDs in China under global warming have not been extensively explored. We revealed two independent routes influencing the formation of winter CDs in China. Furthermore, state‐of‐the‐art climate models project a clear diminish in winter CDs over the Tibetan Plateau and southern China in the mid‐term and long‐term under global warming, providing valuable guidance to policymakers involved in the solar PV power industry. Key Points: The uniform pattern observed in the dominant mode of winter cloudy days (CDs) over China can be attributed to the anomalous southerlies in East AsiaThe warming Arctic forcing and negative convection anomalies over the Maritime Continent both lead to the anomalous southerlies in East AsiaWinter CDs will diminish with enhanced greenhouse forcing, owing to a shift in Eurasian westerly jet affecting the Arctic forcing on East Asian anomalous southerlies [ABSTRACT FROM AUTHOR]

Abstract Changes in winter cloudy days (CDs) exert substantial impacts on agricultural production, public transport, and the solar photovoltaic (PV) power industry. However, the physical mechanism behind the variability of winter CDs over China remains largely unclear, making it challenging to predict the future dynamics of winter CDs. In this study, we explored the spatiotemporal features of winter CDs over China from 1961 to 2013 and identified two independent formation mechanisms associated with its leading mode. Then, we projected the future changes (2021–2099) in winter CDs under global warming constrained by the identified formation mechanisms. Results revealed that: (a) The leading mode of winter CDs from 1961 to 2013 presents a homogeneous pattern. The positive winter CDs anomaly is connected to the anomalous southerlies related to the Eurasian Rossby wave train triggered by the Barents Sea thermal forcing, as well as the Asia‐Pacific zonal geopotential height gradient induced by the convection over the Maritime Continent; (b) Selected state‐of‐the‐art climate models project a notable decrease in winter CDs in the Tibetan Plateau and southern China regions, and almost unchanged winter CDs over northern China, under global warming; (c) In contrast to present‐day mechanisms, in the future, the shift of the Eurasian mean flow will terminate the role of the Barents Sea thermal forcing. Instead, the enhanced convection over the Maritime Continent emerges as the primary contributor to the decline in winter CDs. Our findings provide valuable insights for policymakers in the solar PV industry, particularly in relation to the challenges faced under global warming.

Heavy rainfall (HR) often hits the eastern edge of the Tibetan Plateau (EETP) and causes severe flood and landslide in summer, especially in July. In this study, the authors investigate the interannual variation of July HR events and its possible causes. The maximum number of days with HR in July is located at the EETP in China. It is significantly and negatively correlated with the rainfall in southeastern China. More HR events are accompanied by an anomalous lower-tropospheric anticyclone over southeastern China, a westward movement of the western North Pacific subtropical high, and enhanced rainfall in the Maritime Continent (MC). The MC convection exerts a significant impact on the variation of HR events over EETP. Results from analyses of observations and numerical simulations indicate that the convective heating over the MC induces an anomalous anticyclone over southeastern China and the Ekman pumping effect and circulation-convection feedback play vital roles in the process. The high correlation between the HR events over EETP and the equatorial central Pacific SST depends on the relationship between the MC convection and the equatorial central Pacific SST. The relationship is asymmetric, and only the warm SST anomaly in the equatorial central Pacific is accompanied by fewer HR events over the EETP. [ABSTRACT FROM AUTHOR]