气候变暖是当前全球气候变化的主要发展趋势，也是国内外研究者关注的热点话题 之一。然而，表现为气温上升速率变缓、不变或出现下降趋势的气候变暖停滞(Hiatus) 现象(1998-2012年)成为全球气候变暖过程中的特殊现象，受到国内外学者的广泛关 注。毛乌素沙地生态环境脆弱，对气候变化的响应较为敏感，研宄该区域气候变暖停滞 现象及其气温降水变化特征，探讨这段期间气候变化对植被生长的影响，对于科学调整 区域植被生态环境保护政策具有重要参考价值。基于1970-2019年毛乌素沙地气温和降 水地面观测数据、1982-1999年GIMMSNDVI数据、2000-2019年MODISNDVI数据， 利用线性趋势法、Theil-Sen斜率估计法、Mann-Kendall趋势检验法、相关性分析等方法， 从多时空角度，分析了气候变暖停滞过程中气温降水变化特征及其对植被NDVI变化影 响。主要得到以下结论： 

(1) 1970-2019年毛乌素沙地不同时间尺度(年、季节、月)、空间尺度平均气温、 降水量整体上均呈增加趋势，表现出“暖湿化”特征。1998-2012年，年平均气温变化 速率为-0.70°C/10a,存在明显的Hiatus现象，各季节平均气温均呈下降趋势，其中，冬 季和春季降温速率相对最快；降水量反而呈大幅度不显著增加趋势(47.61mm/10a),夏 季和秋季增加速率相对最快；毛乌素沙地气候变暖停滞现象除冬季表现明显外，主要表 现为9月平均气温降幅最大，同期降水量表现为增幅最大特征；空间尺度上，年际、季 节平均气温表现出大范围减少趋势，但季节表现不明显；年际降水量整体上呈增加趋势， 各个季节降水量局部存在减少趋势O2012年以后，年际和季节平均气温相较于1998-2012 

年呈相反变化趋势，即表现为气温回温，降水量反而呈下降趋势。 

(2) 1982-2019年毛乌素沙地不同时间尺度(年、季节、月)、空间尺度NDVI整 体上均呈显著增加趋势。1998-2012年，年际植被NDVI增加速率大于气候变暖停滞前、 后时期，增加速率(0.31%/10a)为1982-2019年的1.72倍，夏季、秋季NDVI增加对年 际增加贡献最大，冬季植被NDVI增加速率低于气候变暖停滞前、后时期；空间尺度上， 年际和季节整体呈增加趋势，东部比西部明显，其中，冬季研究区中部呈减少趋势，占 研宄区面积的38.72%。 

(3)   毛乌素沙地年际和夏、秋季降水量对NDVI影响大于气温，冬季平均气温对

NDVI 影响大于降水量。1982-2019 年毛乌素沙地年际和季节（除冬季）NDVI 与气温、 降水整体上均表现为正相关，其中，春季平均气温对 NDVI 影响最明显，秋季降水对 NDVI 影响最明显；月 NDVI 对气温、降水量的响应存在一定的滞后性。1998-2012 年，年际 和季节（除冬季）NDVI 与气温整体上表现为负相关，冬季 NDVI 与气温表现为正相关， 中部表现最为明显；年际和季节（除冬季）NDVI 与降水量表现为正相关；月 NDVI 对 气温响应的滞后性小于气候变暖停滞前期（1982-1998 年），对降水量响应的滞后性没有 变化。 

综上所述，毛乌素沙地降水量对植被生长影响大于气温，其中，春季平均气温对 NDVI 影响最大，秋季降水量对 NDVI 影响最大。1998-2012 年存在明显 Hiatus 现象，表 现为年平均气温显著下降、年降水量增加的特征，植被生长整体没有受到影响，仅冬季 植被 NDVI 表现为下降趋势。Hiatus 现象发生期间和结束后的年平均气温增加后减少、 降水量先增加后减少变化，会对毛乌素沙地植被生态环境变化造成一定的负影响，需引 起重视。

Climate warming is the main development trend of global climate change, and it is also one of the hot topics concerned by researchers at home and abroad. However, the phenomenon of global warming Hiatus, which is characterized by the slow, constant or declining rate of temperature rise (1998-2012),  has become a special phenomenon  in  the process of global warming  and  has received  extensive attention  from scholars at home and  abroad.  The ecological environment of Mu Us Sandy Land is fragile, and it is sensitive to climate change. Studying  the phenomenon  of climate warming  stagnation  and  the characteristics of temperature and precipitation in this region, and discussing the impact of climate change on vegetation growth during this period, has important reference value for scientific adjustment of regional vegetation  ecological environmental protection  policy.  Based  on  the surface observation data of temperature and precipitation in Mu Us Sandy Land from 1970 to 2019, GIMMS NDVI data from 1982  to  1999,  and  MODIS NDVI data from 2000  to  2019,  the characteristics of temperature and  precipitation  change in  the process of global warming stagnation and its influence on vegetation NDVI change were analyzed from a multi-temporal

perspective by using linear trend method, Theil-Sen slope estimation method, Mann-Kendall trend test method, and correlation analysis. The main conclusions are as follows : 

(1) From 1970  to  2019,  the average temperature and  precipitation  at different time scales (annual,  seasonal and  monthly) and  spatial scales in  Mu  Us Sandy  Land  showed  an increasing trend, showing the characteristics of * warm and humid From 1998 to 2012, the annual average temperature change rate was -0.70°C/10a,  and  there was an  obvious Hiatus phenomenon.  The average temperature in  each  season  showed  a downward  trend,  and  the cooling  rates in  winter and  spring  were the fastest.  On  the contrary, precipitation increased significantly  (47.61mm/10a),  with  the fastest increasing  rate in  summer and  autumn.  The phenomenon  of climate warming  stagnation  in  Mu  Us Sandy  Land  was obvious except in winter, which mainly showed that the average temperature decreased most in September, and

the precipitation increased most in the same period. On the spatial scale, the annual and seasonal average temperature showed a wide range of decreasing trends, but the seasonal performance was not obvious ; the interannual precipitation showed an overall increasing trend, and the precipitation in each season showed a decreasing trend. After 2012, the interannual and seasonal average temperature showed the opposite trend compared with 1998-2012, that is, the temperature returned, and the precipitation decreased. 

（2）From 1982 to 2019, NDVI at different time scales ( annual, seasonal and monthly ) and spatial scales in Mu Us Sandy Land showed an overall trend of significant increase in indigenous areas. From 1998 to 2012, the increase rate of annual vegetation NDVI was greater than that before and after the stagnation of climate warming, and the increase rate (3.1%/10a) 

was 1.72 times that of 1982-2019. The increase of NDVI in summer and autumn contributed 

the most to the annual increase. The increase rate of NDVI in winter was lower than that before and after the stagnation of climate warming. On the spatial scale, the interannual and seasonal overall showed an increasing trend, and the eastern part was more obvious than the western part. Among them, the central part of the winter study area showed a decreasing trend, accounting for 38.72 % of the study area. 

（3）The influence of interannual, summer and autumn precipitation on NDVI is greater than that of air temperature, and the influence of winter average temperature on NDVI is greater than that of precipitation. The interannual and seasonal ( except winter ) NDVI of the Mu Us Sandy Land from 1982 to 2019 were positively correlated with temperature and precipitation. The spring average temperature had the most obvious effect on NDVI, and the autumn precipitation had the most obvious effect on NDVI. There is a certain lag in the response of monthly NDVI to temperature and precipitation. From 1998 to 2012, inter-annual and seasonal ( except winter ) NDVI was negatively correlated with temperature on the whole, and winter NDVI was positively correlated with temperature, with the most obvious in the middle. interannual and seasonal NDVI ( except winter ) were positively correlated with precipitation ; the lag of monthly NDVI response to temperature was less than that of pre-warming ( 1982-1998 ), and the lag of NDVI response to precipitation did not change. 

In summary, the impact of precipitation on vegetation growth in Mu Us Sandy Land is greater than that of air temperature. Among them, the average temperature in spring has the greatest impact on NDVI, and the precipitation in autumn has the greatest impact on NDVI. There was a significant Hiatus phenomenon from 1998 to 2012, characterized by a significant decrease in annual average temperature and an increase in annual precipitation. Vegetation growth was not affected as a whole, and NDVI showed a downward trend only in winter.During and after the occurrence of Hiatus phenomenon, the annual average temperature increased and then decreased, and the precipitation increased first and then decreased, which should be paid attention to, and may have a negative impact on the vegetation ecological environment change in the Mu Us Sandy Land.