Reconstructing the climate and environmental characteristics of Chengdu in the Middle Tang Dynasty from Du Fu's "Thousand Autumns of Snows"

Through the analysis of the geographical landscapes and climatic information recorded in Tang poems, it is possible to reconstruct the characteristics of the climate and environments of the times in which the poets lived. In this paper, we take the "Four Quatrains (No. 3)" by Du Fu (712—770 AD) and "Ode to Chengdu" by Zhang Ji (767—830 AD) of the Tang Dynasty to gain insight into the climatic conditions of their time, and select "Thousand Autumns of Snows" and "Lychee Ripening" as analyzing elements, then combine them with phenology and GIS to quantitatively reconstruct the temperature, precipitation, and snowline of the Chengdu during the Middle Tang Dynasty. Based on the premise that Chengdu was located at the northern boundary of lychee cultivation during the Tang Dynasty, a spatial analysis of modern lychee distribution points was conducted through GIS. The analysis initially identified the minimum annual mean temperature and annual precipitation of Chengdu during the Middle Tang Dynasty to be (18 ± 0.4) ℃ and (1230 ± 260) mm, which were about 2 ℃ and 250 mm higher than those in modern times. Furthermore, based on the relationship between the modern snowline, temperature and precipitation, the snowline height in Chengdu during the Middle Tang Dynasty is estimated to be (4600 ± 200) m, which is about 700 meters lower than that in modern times. Based on the reconstructed snowline height and GIS visibility analysis, it is hypothesized that the 'Thousand Autumns of Snows' in Du Fu's poem refers to the main peak of Jiu Ding Mountains, Lion King Peak.