陕北黄土高原中部生态修复对局地气候的影响

利用陕北黄土高原2000—2019年MODIS产品的MOD13Q1数据，定边、安塞、志丹、子长、延安气象站1990—2019年月（年）平均气温及最高（最低）气温、降雨量、降雨日数等资料，通过差值（比值）、相关系数、线性回归等方法，对陕北黄土高原生态修复显著区（志丹、安塞、子长、延安）和非显著区（定边）在生态修复前（1990—1999年）和生态修复中（2000—2019年）的气象要素变化进行了对比分析。结果表明：（1）生态修复中显著区、非显著区的归一化植被指数随年份以0.123、0.081/10 a增加，显著区的气温上升速率为非显著区的1.5倍；显著区和非显著区年平均气温分别以0.164、0.467 ℃/10 a速率上升，平均降雨量分别以39.95、25.56 mm/10 a的速率增加，显著区较非显著区升温明显缓慢，但平均降雨量的增加速率明显大于非显著区。（2）生态的显著性修复在2012年之后对年平均气温上升的抑制作用凸显，显著区和非显著区年平均气温差值出现突变发生在2013年，此年为生态修复对年平均气温影响的关键时间点；生态修复显著区在植被生长季（4—9月）对年平均气温上升的抑制较为明显，7月最为明显，显著区较非显著区年平均气温降低了1.05 ℃；对最高气温的抑制出现在7—8月，对最低气温的抑制出现在5—6月。（3）生态修复中（2013—2019年）显著区的降雨日数较修复前明显偏少近6 d，其减少主要是小雨日数的减少，中雨以上的降雨日数均随着生态修复的开展呈增加趋势；显著区植被生长季降雨量增加最为明显，降雨量的增加主要表现为中雨以上降雨日数的增加；1—7月随着植被覆盖度不断增加，显著区与非显著区不同等级降雨日数差值逐渐增大，7月达到最大，8—12月，随着植被覆盖度不断降低，降雨日数的差值又逐渐减小。

Effects of Ecological Restoration on Local Climate in the Middle of Loess Plateau in Northern Shaanxi

Based on the MOD13Q1 data of MODIS products in the Loess Plateau of Northern Shaanxi from 2000 to 2019, the monthly (annual) average temperature, maximum (minimum) temperature, rainfall and rainfall days of Dingbian, Ansai, Zhidan, Zichang, and Yan’an meteorological stations from 1990 to 2019 were used. the difference (ratio), correlation coefficient and linear regression were used. the changes of meteorological elements in the ecological restoration significant areas (SIER; Zhidan, Ansai, Zichang, Yan ''an ) and non-significant area (NSIER; Dingbian) of the Loess Plateau in northern Shaanxi were compared and analyzed before ecological restoration (1990-1999; BER) and during ecological restoration (2000-2019; DER). The results showed that: (1) The normalized differential vegetation index (NDVI) in SIER and NSIER at DER increased by 0.123 and 0.081/10 a, and the rate of temperature rise in SIER was 1.5 times that in NSIER. The annual average temperature in SIER and NSIER increased by 0.164 ℃/10 a and 0.467 ℃/10 a, respectively, and the annual average rainfall increased by 39.95 mm/10 a and 25.56 mm/10 a, respectively. The temperature increase in SIER was significantly slower than in NSIER, but the increase rate of average rainfall was significantly greater than that in NSIER. (2) Significant restoration of ecology had a prominent inhibitory effect on the annual average temperature rise after 2012. the sudden change in the annual average temperature difference of SIER and NSIER occurred in 2013, which is a key time point for the impact of ecological restoration on the annual average temperature. In the vegetation growth season (April-September), the inhibition of the annual average temperature rise in SIER was more obvious, especially in July. The annual average temperature in SIER was 1.05 ℃ lower than that in NSIER. The inhibition of the highest temperature appeared in July-August, and the inhibition of the lowest temperature appeared in May-June. (3) The number of rainfall days in SIER at DER (2013-2019) was significantly less than that BER by nearly 6 days. The decrease was mainly due to the decrease of light rain days. the number of rainfall days above moderate rain showed an increasing trend with the development of ecological restoration. The increase of rainfall in the vegetation growth season in SIER is the most obvious, and the increase of rainfall is mainly manifested in the increase of the number of rainy days above moderate rain. From January to July, with the continuous increase of vegetation coverage, the difference between different grades of rainfall days in SIER and NSIER gradually increased, reaching the maximum in July. From August to December, with the decrease of vegetation coverage, the difference of rainfall days gradually decreased.