春节(又称中国新年或农历新年)是中国最重要的传统节日，通常春节从农历新年前几天开始一直到正月十五元宵节，持续超过2个星期。研究中国东部在大规模的节假日(中国春节)期间的大气物理参数变化及相应的人类活动因子和大气环流反馈的可能影响，可以为客观诊断天气、气候对人类活动强迫的响应提供有价值的观测和理论基础，对于提高天气尺度模式的模拟和预报能力具有重要的科学和实际意义。本文基于长期站点观测数据和再分析资料，系统诊断和分析了春节期间的天气气候效应及导致这一天气气候效应的重要影响因素。主要结果如下：

(1) 对中国东部地区496个观测站点的分析表明，日平均气温、日最高气温和日最低气温在春节期间都有明显的降温特征。记春节当天为第0天，春节前第n天为第?n天，春节后第n天为第+n天，结果表明较大的温度负异常时间段出现在第?3天到+6天。无雨日的情况下，春节降温效应仍然存在且更加明显。各站点空间分布的结果也显示出明显的降温特征。CN05.1、ERA-Interim和ERA5三套资料与站点观测的分析结果较为一致，均显示在春节期间出现异常降温的现象，且量级也接近。不同人口密度等级、不同人均GDP等级的春节降温效应对比显示，随着人类活动强度的增强，中国东部春节期间日平均气温、日最高气温和日最低气温负异常的降温幅度会更大且各站点更趋一致性。长期变化方面，在剥离全球变暖背景后，温度的春节效应的信号仍稳定存在。温度的春节效应变化还存在年代差异，1990年代温度的春节效应是?2.01℃，通过0.05的显著性水平检验，而2000年代则信号较弱为?0.5℃，值不显著。

(2) 基于站点观测数据分析了中国东南地区春节期间降水的异常变化，结果表明长江以南地区(108-123°E和21-33°N, 155个站点)在春节期间的降水频率和降水距平相比春节前后都显著减小。第+4到+6天的平均降水频率距平是?7.4%。同时，日降水量在第+2到+5天减少了0.62mm day^-1。春节假期降水异常和相对湿度以及云量的异常密切相关。站点观测显示相对湿度从第+2到+7天明显减少，最小值出现在第+4到+6天，平均值为?3.9%。从垂直廓线上看，相对湿度在800hPa以下明显变干。在800到1000hPa之间，相对湿度异常的平均值是?3.9%。站点观测的白天低云量在第+4到+6天减少约?6.1%。同时，ERA-Interim日间低云量也在第+4到+6天减少约5%。

(3) 对降水相关的物理量分析表明，异常的相对湿度主要是由对流层中低层水汽的减少引起的。站点观测数据显示，显著的比湿负异常从第?3天持续到第+7天，其中第+4到+6天的平均比湿距平是?0.73g kg^-1。在无雨日情况下，该比湿距平仍然为负值(?0.46g kg^-1)。在700hPa以下有显著的水汽缺失，在800到1000hPa, 平均比湿减少约0.7g kg^-1。对流层中低层的变干是由异常的北风导致的，这一北风是由西北太平洋异常的气旋环流带来的。时间滞后相关的分析证明中国东部地区出现降温后一周左右，西太平洋上出现了强气旋。

(4)春节期间大气环流的异常变化，可能与人为气溶胶及热释放等人类活动因素有关。地面台站观测的PM₁₀和卫星气溶胶光学厚度AOD都显示春节期间气溶胶浓度明显降低，第?4到第?1天PM₁₀减少?12.26 μg m^-3。MACC资料显示对流层中低层的黑碳在第?5天减少?0.15μg kg^-1。分析表明，气溶胶的减少与后期异常气旋的活动强度有显著的关系，当PM₁₀比气旋提前9到6天时相关性最强，相关系数为+0.52到+0.57。当温度比气压场提前4 到5天时，相关系数达到最大值，为+0.52。这些结果说明伴随中国东部PM₁₀浓度和温度的下降，西太平洋地区易出现一个异常的气旋，其强度约一周后最强。针对冷源对异常气旋的可能影响进行了数值试验。采用线性斜压模式(LBM)验证发现中国东部地区，冬季对流层中低层有异常冷源强迫时，会在一周左右产生大气环流异常，生成气旋。

Chinese New Year (also known as Chinese New Year or Lunar New Year) is the most important traditional festival in China, which usually lasts for more than two weeks starting from a few days before the Lunar New Year until the Lantern Festival on the 15th day of the first month. Investigating the changes of atmospheric physical parameters and the possible effects of corresponding anthropogenic factors and atmospheric circulation feedbacks during the Chinese New Year in eastern China is of great scientific and practical importance to understand the weather and climate response to anthropogenic forcing, and to enhance the simulation and forecasting capability of weather models. In this thesis, we systematically diagnose and analyze the weather and climate effects during the Spring Festival and the critical influencing factors leading to this weather and climate effect based on long-term station observational data and reanalysis data. The main results are as follows.

(1) The analysis of 496 observation stations in eastern China shows that the daily average temperature, daily maximum temperature and daily minimum temperature have significant cooling characteristics during the Chinese New Year. The day of Chinese New Year is recorded as day 0, the nth day before Chinese New Year is day ?n, and the nth day after Chinese New Year is day +n. The results show that the larger negative temperature anomalies occur during days [?3, +6]. The cooling effect of Chinese New Year remains and becomes more pronounced in the cases of the no-rain days. The results of the spatial distribution of the observation stations also show a significant cooling effect. The three sets of reanalysis data, CN05.1, ERA-Interim and ERA5, are in good agreement with the results of the observation station, and all of them show anomalous cooling during the Spring Festival, and the magnitudes are similar. The comparison of the Spring Festival cooling effects for different population density classes and different per capita GDP classes shows that the cooling magnitude of the negative anomalies of daily average temperature, daily maximum temperature and daily minimum temperature during the Spring Festival in eastern China becomes larger and more consistent across stations as the intensity of human activities increases. In terms of long-term changes of the Spring Festival temperature effect, the signal of the Spring Festival temperature effect remains stable after stripping the global warming background. There is also a chronological variation in the Spring Festival temperature effect, with the Spring Festival temperature effect in the 1990s being ?2.01°C, which meets the significance level of 0.05, while the signal in the 2000s is weaker at ?0.5°C, with a non-significant value.

(2) The anomaly variation of precipitation during the Spring Festival in southern China is analyzed based on station observations, and the results show that the precipitation frequency and precipitation amount during the Spring Festival in the area south of the Yangtze River (108-123°E and 21-33°N, 155 stations) are significantly reduced compared with those before and after the Spring Festival. The average precipitation frequency anomaly is ?7.4% during days [+4, +6]. At the same time, the daily precipitation amount decreased by 0.62 mm day^-1 during days [+2, +5]. The precipitation anomalies during the Spring Festival holiday are closely related to the anomalies in relative humidity and cloud cover. Station observations show a significant decrease in relative humidity during days [+2, +7], with the minimum value occurring during days [+4, +6] and an average value of ?3.9%. From the vertical profile, the relative humidity becomes significantly drier below 800hPa. Between 800hPa and 1000hPa, the average value of the relative humidity anomaly is ?3.9%. Daytime low cloud cover from the station observations decreases by about ?6.1% during days [+4, +6]. At the same time, the ERA-Interim daytime low cloud cover also decreases by about 5% during days [+4, +6].

(3) The analysis of precipitation-related physical variables shows that the relative humidity anomalies are mainly caused by the reduction of water vapor in the lower troposphere. Station observations show that significant negative specific humidity anomalies persist during days [?3, +7], where the average specific humidity anomaly is ?0.73 g kg^-1 during days [+4, +6]. The specific humidity anomaly remains negative (?0.46 g kg^-1) in the case of no-rain days. The dryness in the lower and middle troposphere is caused by an anomalous northern wind, which is generated by an anomalous cyclonic circulation in the northwest Pacific. The analysis of the time lag correlation demonstrates that a strong cyclone appeared in the western Pacific about a week after the cooling occurred in eastern China.

(4) The anomalous changes in atmospheric circulation during the Spring Festival may be related to anthropogenic factors such as anthropogenic aerosols and anthropogenic heat release. Both PM₁₀ from ground stations and satellite aerosol optical thickness (AOD) show a significant decrease in aerosol concentration during the Spring Festival, with PM10 decreasing by ?12.26 μg m^-3 during days [?4, ?1]. The Monitoring Atmospheric Composition and Climate Interim Implementation (MACC) data show a decrease of ?0.15 μg kg^-1 of black carbon in the lower and middle troposphere on the ?5day. The analysis shows that the decrease of aerosol is significantly related to the intensity of the late anomalous cyclone activity, with the strongest correlation of +0.52 to +0.57 when PM₁₀ is nine to six days ahead of the cyclone, and the correlation coefficient reaches the maximum when the temperature is four to five days ahead of the pressure field, with a correlation coefficient of +0.52. These results suggest that along with the decrease of PM₁₀ concentration and temperature in eastern China, the western Pacific region is likely to have an anomalous cyclone with the strongest intensity about a week later. Numerical experiments are performed for the possible effects of cold sources on the anomalous cyclone. The Linear Baroclinic Model (LBM) is used to validate and find that in eastern China, when there is an anomalous cold source forcing in the lower and middle troposphere in winter, an atmospheric circulation anomaly is generated and a cyclone is generated in about a week.