北京地区热度日和冷度日的变化特征

Characteristics of Heating Degree Days and Cooling Degree Days in Beijing

应用1951—2004年北京逐日平均温度制作北京月、年的热度日(HDD)和冷度日(CDD)。其中平均月HDD以1月(687.9度日)最大,多年平均的年值为2922.6度日,多年变化呈明显的下降趋势,下降率为-99.5度日/10 a。平均月CDD以7月(259.2度日)最大。CDD多年平均的年值为826.7度日,多年变化呈上升趋势,上升率为39.0度日/10 a。1971—2004年HDD月城郊差值(北京站-密云站)冬季较大,最大值为-73.8度日(12月)。月CDD的城郊差值比HDD的差值小,最大差值在8月(34.0度日)。年HDD和CDD与年平均气温具有较高的相关性。年际、年代际HDD与年际、年代际平均气温具有反位相变化趋势,随着气候增暖,北京地区HDD将趋于减小,冬季用于供暖的能源将减少;CDD将趋于增加,夏季用于制冷降温的能源将增加。

Degree-day is a quantitative index demonstrated to reflect the demand for energy to heat or cool houses and businesses. The heating degree days （HDD） index is defined as the accumulated Celsius degrees between the daily mean temperature and a threshold temperature when the mean daily temperature is lower than the threshold value. The cooling degree days （CDD） index is defined analogically as the accumulated Celsius degrees between a threshold temperature and the daily mean temperature when the mean daily temperature is higher than the threshold value. The 18℃ threshold temperature is chosen in Beijing. The HDD is a good estimation of an accumulated cold during the cold season as well as an index for heating energy consumption within the heating season. The CDD estimates an accumulated warmth during the warm season as well as the cooling energy consumption within warm season. The mean daily temperature during 1951-2004 from Beiiing Weather Observatory is collected to calculate HDD and CDD. The mean monthly maximum HDD is 687.9 degree-day in January and zero in July. The annual mean value of HDD equals 2922.6 degree-day. There is a decreasing trend of - 99.5 degree-day per decade. The mean monthly maximum CDD is 259.2 degree-day in July. All CDD in January, February, March, November and December are zero. The annual mean value of CDD in warm season is 826.7 degree-day. There is a increasing trend of 39.0 degree-day for CDD per decade. The mean maximum difference of HDD between Beijing station and Miyun station in 1971-2004 is - 73.8 degree-day in December. The mean maximum difference of CDD between Beijing station and Miyun station in 1971-2004 is 34.0 degree-day in August. The annual ItDD, CDD are highly correlated with the annual temperatures. With the temperature warming in Beijing, the smaller the HDD, the less the energy consumption in winter; the larger the CDD, the more the energy consumption in summer in the future.