Abstract: Background, aim, and scope: Yan’an is located on the northern part of the Loess Plateau as well as the edge of the Asian summer monsoon. Because of the monsoon climatic condition, Yan’an is considered to be a sensitive place to study the impacts of global warming on regional climate change. Materials and methods Based on the daily average temperature data of Yan’an Meteorological Station from 1951 to 2012, the five-day moving average method and linear regression method were performed to study the onset day, end day, duration and activity accumulated temperature of the boundary temperature ≥10°C. Correlations between the variables mentioned above and the annual average temperature were analyzed. Results The results showed that the onset day series of the boundary temperature ≥10°C displaying an advanced trend with a tendency rate of -1.845 d·(10a)-1, the delayed trend existed in the end day series with a change rate of 2.437 d·(10a)-1, the duration was prolonged with a rate of 4.189 d·(10a)-1, and the activity accumulated temperature increased with a rate of 106.57°C·(10a)-1. The onset day, end day, duration and activity accumulated temperature of the boundary temperature ≥10°C were significantly correlated with the annual average temperature. The highest correlation coefficient between the active accumulated temperature and the annual average temperature was 0.882. The regression analysis showed that the activity accumulated temperature ≥10℃ could increase 217°C when the annual average temperature enhanced 1°C. Discussion Global warming has a wide-ranging impact on the natural environment and human society. The analysis of special temperature features on the regional and local scales could be useful to reduce the adverse effects of climate change and improve adaptability. Conclusions The variables of temperature ≥10℃ including the onset day, end day, duration and activity accumulated temperature generally showed trends consistent with global warming from 1951 to 2012, which confirmed the regional temperature variation coinciding with the global scale context. Recommendations and perspectives The variations of special temperature such as the boundary temperature ≥10°C are very important to sustainable development of regional natural environment and human society. To identify the features of the onset day, end day, duration and temperature in a long-term span could be helpful to reduce climate disaster risks and improve defense against global warming in the future.
Keywords: activity accumulated temperature; characteristic analysis; Yan’an