摘要
1.1夏季青藏高原积雪异常与同期梅雨降水的关联高分辨率的卫星资料（EASE-grid）显示，在青藏高原西部、南部等高海拔地区夏季仍存在积雪。该地区的积雪异常可以调节青藏高原陆面加热，进而影响青藏高原西部的垂直运动，并通过经向垂直环流调节北印度洋地区的垂直上升运动。同时，通过热带地区的纬向垂直环流和开尔文波（Kelvinwave）响应，北印度洋异常垂直运动可以造成西北太平洋副热带高压异常，也对西太平洋暖池的对流活动具有重要的影响。因此，青藏高原高海拔地区的夏季积雪能够影响东亚-太平洋遥相关型（EAP）和相应的东亚梅雨区夏季降水异常（图1a）。
1.1The summer snow cover anomaly over the Tibetan Plateau and its association withsimultaneous precipitation over the Meiyu–Baiu regionThe satellite-derived Equal-Area Scalable Earth grid(EASE-grid)dataset shows that snow still existsin summer in the western part and along the southern fl ank of the Tibetan Plateau(TP).The summer snowanomaly over the TP can directly modulate the land surface heating and,consequently,vertical motion over thewestern TP,and concurrently induce anomalous vertical motion over the North Indian Ocean via a meridionalvertical circulation.Through a zonal vertical circulation over the tropics and a Kelvin wave-type response,anomalous vertical motion over the North Indian Ocean may result in the anomaly of the western North Pacifi csubtropical high and modulate the convective activity in the western Pacifi c warm pool,which stimulates theEast Asia-Pacifi c(EAP)pattern and eventually affects summer precipitation over the Meiyu-Baiu(MB)region(Fig.1a).
