Abstract:

Based on the observation data of meteorological stations in the Qinling-Huaihe region from 1970 to 2019, with daily average temperature stability ≥10℃continuous days as the main indicator, and January average temperature as the auxiliary indicator, with the help of Thin Plate Spline (TPS) and the ordinary Kriging interpolation method based on Digital Elevation Model (DEM), to explore the response and changes of the subtropical northern boundary in Qinling-Huaihe region to global warming and warming hiatus. From 1970 to 2019, the daily average temperature stability≥10℃continuous days in Qinling-Huaihe region and the January average temperature showed an upward trend of varying degrees, but the distribution years of the high and low values were different. In the past 50 years, the subtropical northern boundary has shown an obvious trend of moving to high-altitude areas in the Qinling section. Among them, the southern slope of the Qinling Mountains has been uplifted by 153.3 m in total, and the northern slope has been uplifted by 148.8 m. During the period of warming hiatus, the elevation changes of the subtropical northern boundary of the southern and northern slopes of the Qinling Mountains were highly synchronized, but they were quite different from 1980s to 1990s. From 1970 to 2019, the subtropical northern boundary moved northward by more than 1.3 latitudes in the Huaihe River section, and even reached 3 latitudes near 115°E, which is similar to the northernmost position that the subtropical northern boundary of China has reached in the past 2000 years. From the perspective of different ages, the northward movement of the subtropical northern boundary was most obvious during the 1990s, parts of the lower Yellow River basin have been gradually transformed from warm temperate to subtropical.

Key words: Qinling Mountains, Huaihe River, Daily average temperature stability≥10℃continuous days, January mean temperature, Subtropical northern boundary