关键词: 初霜日, 终霜日, 无霜日, 霜冻强度, 霜冻区划, 青藏高原

Abstract: Long term gridded meteorological data in 1961-2018 was used in this study instead of in situ observation in previous studies. The spatial and temporal patterns of frost identification thresholds, frost occurrence frequency and frost intensity in the mainland China were investigated through trend analysis and cluster analysis, in order to use climate resources under climate change and reduce the losses caused by frost disasters to agricultural production. The main results were as follows, (1) for screen threshold for frost hazards, the frost date information including first frost date, last frost date and frost free days was detected with detailed geographically spatial pattern and reasonable spatial feature in the threshold of daily 2m minimum air temperature of 0℃ than the ones detected by the threshold of daily 2m minimum air temperature of 2℃.（2）In 1961−2018, first frost date in most China was generally delayed (1−3d·10y−1), and last frost date is advanced. Both of them induced the frost-free days’ increase (1−3d·10y−1). （3）The annual frequency of different frosts intensities had a weakly increased in northern China and obviously decreased in southern China. And the annual frequency of spring frost in different intensities was higher than that of autumn frost in different intensities. （4）The frost hazard’s regionalization clustered by frost date and frequency of frost intensity had five sub-regions, which were subtropical zone, warm tropical zone, middle temperate zone, cold temperate zone, and Qinghai-Tibet Plateau zone. In these sub-regions, the Qinghai-Tibet plateau zone had the most dramatic variation in frost dates. Generally, the warming trend in China had a significant weakening effect on the occurrences of frost damage in time, space and intensity.

Key words: First frost date, Last frost date, Frost-free days, Frost intensity, Frost hazards regionalization, Qinghai-Tibet plateau