Characteristics of agricultural climatology in Baoji over the last 50 years | 陕西宝鸡市近50年农业气候资源特征分析

Chinese. 研究陕西宝鸡市近50年农业气候资源的变化规律。选用宝鸡市11个县（区）气象站的1961―2008年气温、降水量和日照等气象要素统计资料，对宝鸡市近50年光资源、热量资源和水资源的变化特征进行分析。年日照时数以38.95 h/10年的倾向率波浪式减少，其中以夏季减少趋势最明显，线性倾向率为-28.8 h/10年；年平均气温以0.238 ℃/10年倾向率上升，冬、春季平均气温上升最快，夏季平均气温升温幅度最小；年降水量以倾向率为31.187 mm/10年波动性减少，这种减少主要是由于春季和秋季降水量减少而致。由于气温升高，各农业界限温度的初日明显提前，终日推迟，持续时间明显增多，积温显著增加，以平均气温≥0 ℃和平均气温≥10 ℃时各指标变化较明显，平均气温≥20 ℃时各指标变化较小。近50年，由于气候变化，宝鸡市农业气候资源发生了明显变化，使农业生产的不稳定性增加、产量波动加大。

English. Study on the change of agro-climatic resources in Baoji city, Shaanxi Province in last 50 years was conducted. Statistics of meteorological variables such as temperature, rainfall and sunlight timeat 11 weather stations in Baoji city from 1961 to 2008 was calculated to analyse variation characteristics of light, heat and water resources. The annual sunshine hours tended to decrease with a rate of 38.95 h/10 year. The strongest reduction happened at summer with a rate of －28.8 h/10 year. Annual average temperature tended to rise at a rate of 0.238 ℃/10 year. In winter and spring the increase of average temperature was faster while in summer it was lower. Annual precipitation reduced fluctuatively with a rate of 31.187 mm/10 year, which was mostly due to the reduction of precipitation in spring and autumn. Due to rising temperature, the starting date of agricultural threshold temperature shifted earlier, the ending date deferred, the duration increased by a number of days and accumulated temperature increased significantly. Those variables changed sigficantly when a mean temperature of ≥0 ℃ or ≥10 ℃ was used while they barely changed when using a mean temperature of ≥20 ℃. Apparent changes in the agro-climatic resources in Baoji city occurred in last 50 years due to climate change, increasing the instability of agricultural production and output.